知財求人 - 知財ポータルサイト「IP Force」
(19)【発行国】日本国特許庁(JP)
(12)【公報種別】公開特許公報(A)
(11)【公開番号】P2023028822
(43)【公開日】2023-03-03
(54)【発明の名称】充電装置
(51)【国際特許分類】
H02J 7/02 20160101AFI20230224BHJP
H02J 7/00 20060101ALI20230224BHJP
H02J 1/00 20060101ALI20230224BHJP
【ＦＩ】
H02J7/02 F
H02J7/00 303A
H02J1/00 306L
【審査請求】未請求
【請求項の数】9
【出願形態】ＯＬ
【外国語出願】
(21)【出願番号】P 2021134749
(22)【出願日】2021-08-20
(71)【出願人】
【識別番号】000005108
【氏名又は名称】株式会社日立製作所
(74)【代理人】
【識別番号】110000350
【氏名又は名称】ポレール弁理士法人
(72)【発明者】
【氏名】チョデリ アビジタ
(72)【発明者】
【氏名】叶田 玲彦
【テーマコード（参考）】
5G165
5G503
【Ｆターム（参考）】
5G165CA01
5G165CA04
5G165CA05
5G165DA01
5G165DA06
5G165EA06
5G165FA01
5G165GA09
5G165HA01
5G165JA04
5G165LA02
5G165MA01
5G165MA10
5G165NA01
5G165NA05
5G165NA09
5G503AA01
5G503BA02
5G503CA01
5G503CA11
5G503EA05
5G503FA06
(57)【要約】
【課題】
電圧アンバランスを抑制できる充電装置を開示する。
【解決手段】
充電装置［１２７］は、複数のコンバータユニット［１１６］と、複数のコンバータユニットが接続される入力ポートと複数の蓄電装置が接続される出力ポートとを有するマトリクススイッチ［１２０］と、コンバータユニットの出力電流およびマトリクススイッチを制御する制御ユニット［１２８］と、を備える。コンバータユニットは、ＡＣ／ＤＣ変換回路［１０９］と、キャパシタを介してＡＣ／ＤＣ変換回路に接続されるＤＣ／ＤＣ変換回路［１１２］とを有するコンバータセル［１０８］を備える。複数のＡＣ／ＤＣ変換回路の複数の交流入力端子は互いに直列に接続される。制御ユニットは、コンバータユニットの出力電流を所定値まで低減し、その後、マトリクススイッチにおける入力ポートと出力ポートとの間の接続状態を再構成する。
【選択図】図１
電圧アンバランスを抑制できる充電装置を開示する。
【解決手段】
充電装置［１２７］は、複数のコンバータユニット［１１６］と、複数のコンバータユニットが接続される入力ポートと複数の蓄電装置が接続される出力ポートとを有するマトリクススイッチ［１２０］と、コンバータユニットの出力電流およびマトリクススイッチを制御する制御ユニット［１２８］と、を備える。コンバータユニットは、ＡＣ／ＤＣ変換回路［１０９］と、キャパシタを介してＡＣ／ＤＣ変換回路に接続されるＤＣ／ＤＣ変換回路［１１２］とを有するコンバータセル［１０８］を備える。複数のＡＣ／ＤＣ変換回路の複数の交流入力端子は互いに直列に接続される。制御ユニットは、コンバータユニットの出力電流を所定値まで低減し、その後、マトリクススイッチにおける入力ポートと出力ポートとの間の接続状態を再構成する。
【選択図】図１
【特許請求の範囲】
【請求項1】
複数の蓄電装置を充電する充電装置において、
交流電力を入力し、かつ直流電力を出力する複数のコンバータユニットと、
前記複数のコンバータユニットの複数の出力が接続される複数の入力ポートと、前記複数の蓄電装置が接続される複数の出力ポートとを有するマトリクススイッチと、
前記複数のコンバータユニットの出力電流を制御するとともに、前記マトリクススイッチにおける複数の開閉器を制御する制御ユニットと、
を備え、
前記複数のコンバータユニットの各々は、
前記交流電力を入力するＡＣ／ＤＣ変換回路と、キャパシタを介して前記ＡＣ／ＤＣ変換回路に接続され、かつ前記直流電力を出力するＤＣ／ＤＣ変換回路とを有するコンバータセルを備え、
複数の前記ＡＣ／ＤＣ変換回路の複数の交流入力端子は互いに直列に接続され、
前記制御ユニットは、前記蓄電装置を前記出力ポートに接続するとき、もしくは前記蓄電装置を前記出力ポートから切り離すとき、前記複数のコンバータユニットの出力電流を所定値まで低減し、その後、前記制御ユニットは、前記マトリクススイッチにおける前記複数の入力ポートと前記複数の出力ポートとの間の接続状態を再構成することを特徴とする充電装置。
交流電力を入力し、かつ直流電力を出力する複数のコンバータユニットと、
前記複数のコンバータユニットの複数の出力が接続される複数の入力ポートと、前記複数の蓄電装置が接続される複数の出力ポートとを有するマトリクススイッチと、
前記複数のコンバータユニットの出力電流を制御するとともに、前記マトリクススイッチにおける複数の開閉器を制御する制御ユニットと、
を備え、
前記複数のコンバータユニットの各々は、
前記交流電力を入力するＡＣ／ＤＣ変換回路と、キャパシタを介して前記ＡＣ／ＤＣ変換回路に接続され、かつ前記直流電力を出力するＤＣ／ＤＣ変換回路とを有するコンバータセルを備え、
複数の前記ＡＣ／ＤＣ変換回路の複数の交流入力端子は互いに直列に接続され、
前記制御ユニットは、前記蓄電装置を前記出力ポートに接続するとき、もしくは前記蓄電装置を前記出力ポートから切り離すとき、前記複数のコンバータユニットの出力電流を所定値まで低減し、その後、前記制御ユニットは、前記マトリクススイッチにおける前記複数の入力ポートと前記複数の出力ポートとの間の接続状態を再構成することを特徴とする充電装置。
【請求項2】
請求項１に記載の充電装置において、
前記制御ユニットは、前記マトリクススイッチにおける前記複数の入力ポートと前記複数の出力ポートとの間の前記接続状態を再構成した後、前記複数のコンバータユニットの出力電流指令を設定することを特徴とする充電装置。
前記制御ユニットは、前記マトリクススイッチにおける前記複数の入力ポートと前記複数の出力ポートとの間の前記接続状態を再構成した後、前記複数のコンバータユニットの出力電流指令を設定することを特徴とする充電装置。
【請求項3】
請求項１に記載の充電装置において、
高電圧キャパシタ電圧リプルが前記電圧の基準値の３０％未満に保たれることを特徴とする充電装置。
高電圧キャパシタ電圧リプルが前記電圧の基準値の３０％未満に保たれることを特徴とする充電装置。
【請求項4】
請求項１に記載の充電装置において、
前記出力電流の前記所定値が零に低減され得ることを特徴とする充電装置。
前記出力電流の前記所定値が零に低減され得ることを特徴とする充電装置。
【請求項5】
請求項１に記載の充電装置において、
前記制御ユニットは、前記マトリクススイッチにおける前記複数の入力ポートと前記複数の出力ポートとの間の前記接続状態を再構成してから所定の遅延時間後、前記複数のコンバータユニットの出力電流指令を設定することを特徴とする充電装置。
前記制御ユニットは、前記マトリクススイッチにおける前記複数の入力ポートと前記複数の出力ポートとの間の前記接続状態を再構成してから所定の遅延時間後、前記複数のコンバータユニットの出力電流指令を設定することを特徴とする充電装置。
【請求項6】
請求項５に記載の充電装置において、
前記所定の遅延時間は、１μｓｅｃ以上であることを特徴とする充電装置。
前記所定の遅延時間は、１μｓｅｃ以上であることを特徴とする充電装置。
【請求項7】
請求項１に記載の充電装置において、
複数のコンバータユニットの各々は、互いにＤＣ出力が並列に接続された複数の前記コンバータセルを備えることを特徴とする充電装置。
複数のコンバータユニットの各々は、互いにＤＣ出力が並列に接続された複数の前記コンバータセルを備えることを特徴とする充電装置。
【請求項8】
請求項１に記載の充電装置において、
前記蓄電装置の充電スピードが設定できることを特徴とする充電装置。
前記蓄電装置の充電スピードが設定できることを特徴とする充電装置。
【請求項9】
請求項１に記載の充電装置において、
前記ＡＣ／ＤＣ変換回路および前記ＤＣ／ＤＣ変換回路は双方向型電力変換回路であることを特徴とする充電装置。
前記ＡＣ／ＤＣ変換回路および前記ＤＣ／ＤＣ変換回路は双方向型電力変換回路であることを特徴とする充電装置。
【発明の詳細な説明】
【技術分野】
【0001】
本発明は、蓄電池などの蓄電装置に充電電力を供給する充電装置に関する。
【背景技術】
【0002】
近年、電気自動車用充電装置の大容量化により、中高圧絶縁型ＡＣ／ＤＣコンバータを備えた充電装置が適用されつつある。なお、以下、「電気自動車」（electric vehicle）は、「ＥＶ」と記載する。
【0003】
中高圧絶縁型ＡＣ／ＤＣコンバータを備えた充電装置に関する従来技術として、特許文献１に記載の技術が知られている。
【0004】
特許文献１に記載の技術では、各々が絶縁型ＡＣ／ＤＣコンバータからなる複数台のコンバータセルの交流入力が互いに直列接続される。直列接続された交流入力は、変圧器を介することなく、高電圧の交流電源系統に直接、接続される。
【0005】
各コンバータセルは、交流入力を有するＡＣ／ＤＣ変換回路と、ＡＣ／ＤＣ変換回路の直流側に接続される平滑キャパシタと、交流側がＡＣ／ＤＣ変換回路の直流側に接続されるＤＣ／ＡＣ変換回路と、一次巻線がＤＣ／ＡＣ変換回路の交流側に接続される高周波トランスと、交流側が高周波トランスの二次巻線に接続され、直流出力を有するＡＣ／ＤＣ変換回路とを備えている。
【0006】
複数台のコンバータセルの直流出力は、切替器の複数の入力ポートに接続される。切替器においては、複数の入力ポートと複数の出力ポートの間に、開閉器がマトリクス状に接続される。このため、開閉器を操作することにより、各コンバータセルの直流出力が任意の出力ポートに接続される。各コンバータセルは、出力ポートに接続される負荷である電気自動車の蓄電池に直流電力を供給して、蓄電池を充電する。
【先行技術文献】
【特許文献】
【0007】
【特許文献1】国際公開第２０１９／２３４９８８号
【発明の概要】
【発明が解決しようとする課題】
【0008】
上記従来技術では、複数の出力ポートにおける負荷の接続状態が変化すると、複数の平滑キャパシタの直流電圧にアンバランスが生じる。アンバランスが生じると、回路が故障する恐れがある。
【0009】
そこで、本発明は、負荷の接続状態が変動しても、電圧アンバランスを抑制できる充電装置を提供する。
【課題を解決するための手段】
【0010】
上記課題を解決するために、本発明による充電装置は、複数の蓄電装置を充電するものであって、交流電力を入力し、かつ直流電力を出力する複数のコンバータユニットと、複数のコンバータユニットの複数の出力が接続される複数の入力ポートと複数の蓄電装置が接続される複数の出力ポートとを有するマトリクススイッチと、複数のコンバータユニットの出力電流を制御するとともにマトリクススイッチにおける複数の開閉器を制御する制御ユニットと、を備える。複数のコンバータユニットの各々は、交流電力を入力するＡＣ／ＤＣ変換回路と、キャパシタを介してＡＣ／ＤＣ変換回路に接続されかつ直流電力を出力するＤＣ／ＤＣ変換回路とを有する、コンバータセルを備える。複数のＡＣ／ＤＣ変換回路の複数の交流入力端子は互いに直列に接続される。制御ユニットは、蓄電装置を出力ポートに接続するとき、もしくは蓄電装置を出力ポートから切り離すとき、複数のコンバータユニットの出力電流を所定値まで低減し、その後、制御ユニットは、マトリクススイッチにおける複数の入力ポートと複数の出力ポートとの間の接続状態を再構成する。
【発明の効果】
【0011】
本発明によれば、電圧のアンバランスを抑制できる。
【0012】
上記した以外の課題、構成および効果は、以下の実施形態の説明により明らかにされる。
【図面の簡単な説明】
【0013】
【発明を実施するための形態】
【0014】
以下、本発明の実施形態について、図面を用いながら説明する。各図において、参照番号が同一のものは、同一の構成要件あるいは類似の機能を備えた構成要件を示している。
【0015】
図１は、本発明の一実施形態である、電気自動車用の充電装置の構成を示すブロック図である。
【0016】
充電装置［１２７］は、三相四線式のＡＣ電源［１００］から、三相リアクトル［１０２］を介して三相ＡＣ電力を入力する複数（ｍ台）のコンバータ部１１６を有する。「ｍ」は２以上の整数である。各コンバータ部１１６は、ＡＣ電源［１００］の一相から単相ＡＣ電力を入力するコンバータセル［１０８］を三相分（すなわち３台）有する。各コンバータセル［１０８］は、単相ＡＣ電力をＤＣ電力に変換するＡＣ／ＤＣ変換回路［１０９］と、ＡＣ／ＤＣ変換回路［１０９］が出力するＤＣ電力を、電圧が異なるＤＣ電力に変換するＤＣ／ＤＣ変換回路［１１２］とからなる。ＡＣ／ＤＣ変換回路［１０９］のＤＣ出力端子とＤＣ／ＤＣ変換回路［１１２］のＤＣ入力端子は、ＤＣバス［１１０，１１１］によって接続される。
【0017】
複数（ｍ台）のコンバータ部［１１６］において、各コンバータ部［１１６］が備える三相分（三台）のコンバータセル［１０８］の内の一相分のＡＣ入力が、互いに直列に接続される。すなわち、複数（ｍ個）のＡＣ／ＤＣ変換回路［１０９］の各々のＡＣ入力端子［１０３，１０４］が、互いに直列に接続される。ＡＣ入力端子の直列接続の一端および他端［１０６］は、それぞれ、ＡＣ電源［１００］の一相（例えば、Ｕ相）およびＡＣ電源［１００］の中性点Ｎに接続される。これにより、コンバータセル［１０８］の入力を、変圧器を介することなく、高電圧（例えば、６．６ｋＶや１１ｋＶ）のＡＣ電源［１００］に直接接続することができる。
【0018】
各コンバータユニット［１１６］が備える三相分（三台）のコンバータセル［１０８］のＤＣ出力は、互いに並列に接続される。すなわち、三相分（三台）のＤＣ／ＤＣ変換回路［１１２］のＤＣ出力端子［１１３，１１４］が並列に接続される。これにより、各コンバータユニット［１１６］のＤＣ出力が構成される。
【0019】
マトリクススイッチ［１２０］は、複数（ｍ個）の入力ポートと複数（ｎ個）の出力ポートを有する。マトリクススイッチ［１２０］は、複数（ｍ個）の入力ポートと複数（ｎ個）の出力ポートとの間に、ｍ行ｎ列のマトリクス状に配置される、ｍ×ｎ個の開閉器を有する。複数（ｍ台）のコンバータユニット［１１６］の各ＤＣ出力は、複数（ｍ個）の入力ポートの内の異なる入力ポートに、ＤＣバス［１１５］を介して接続される。これら開閉器を操作することにより、各入力ポートと任意の出力ポートとが電気的に接続される。
【0020】
なお、マトリクススイッチ［１２０］における開閉器としては、電磁式や電子式の開閉器が適用される。
【0021】
マトリクススイッチ［１２０］の複数（ｎ個）の出力ポートの各々は、接続ケーブル［１２１］を介して、ＥＶ用充電ポート［１２２］（充電スタンド）に電気的に接続される。複数（ｎ台）のＥＶ用充電ポート［１２２］（充電スタンド）の各々には、充電用ケーブル［１２５］を介してＥＶ［１２４］が接続される。
【0022】
マトリクススイッチ［１２０］が操作されて、複数（ｍ台）のコンバータユニット［１１６］のいずれかのＤＣ出力が接続されると、コンバータユニット［１１６］が出力するＤＣ電力が、ＥＶ［１２４］が搭載する蓄電池に充電される。マトリクススイッチ［１２０］における複数の開閉器を制御することによって、コンバータユニット［１１６］のＤＣ出力が、ＥＶに接続されたり、ＥＶとの接続が解除されたりする。また、マトリクススイッチ［１２０］の開閉制御により、高速充電などの場合に、複数（例えば、２台）のコンバータユニット［１１６］のＤＣ出力を、一台のＥＶに接続することができる。
【0023】
制御ユニット［１２８］は、充電装置［１２７］における電圧および電流情報［１２９］、電圧もしくは電流基準値［１３１］、および複数（ｎ台）のＥＶ用充電ポート［１２２］（充電スタンド）すなわち充電ポート群［１３２］からのＥＶ側情報［１３３］に基づいて、マトリクススイッチ［１２０］の開閉制御や、各コンバータセル［１０８］のＤＣ出力電力制御のための、マトリクススイッチ［１２０］および各コンバータセル［１０８］に対する駆動信号［１３０］を生成する。
【0024】
本実施形態において、電圧および電流情報［１２９］は、各コンバータセル［１０８］におけるＡＣ／ＤＣ変換回路［１０９］とＤＣ／ＤＣ変換回路［１１２］とを接続するＤＣバス電圧［１１７］と、各コンバータユニット［１１６］のＤＣ出力［１１５］における電圧および電流［１１８］である。電圧および電流情報［１２９］は、それぞれ電圧センサおよび電流センサによって検出される。
【0025】
また、本実施形態において、ＥＶ側情報［１３３］は、ＥＶの蓄電池の充電状態（ＳＯＣ）に関するＳＯＣ情報［１２３］、充電スピード（低速、中速、急速）などのユーザ設定情報、ＥＶ用充電ポート（充電スタンド）［１２２］へのＥＶの接続・非接続に関するＥＶ接続情報を含む。ＳＯＣ情報［１２３］は、充電用ケーブル［１２５］が備える通信線と、ＥＶ用充電ポート（充電スタンド）［１２２］とを介して、制御ユニット［１２８］へ送信される。ユーザ設定情報は、ＥＶ用充電ポート（充電スタンド）［１２２］のスイッチ装置やボタン操作によって設定される。ＥＶ接続情報はＥＶ用充電ポート（充電スタンド）［１２２］によって検出される。ユーザ設定情報およびＥＶ接続情報は、ＥＶ用充電ポート（充電スタンド）［１２２］によって制御ユニット［１２８］へ送信される。
【0026】
図２は、ＡＣ／ＤＣ変換回路［１０９］の一例を示す回路図である。
【0027】
図２に示すように、ＡＣ／ＤＣ変換回路［１０９］は、半導体スイッチング素子（図２では、ＩＧＢＴ）とダイオードが逆並列に接続された半導体装置［２００］が用いられる単相フルブリッジ回路と、単相フルブリッジ回路に並列に接続されるＤＣリンクキャパシタ［２０１］とからなる。各ハーフブリッジ回路における２個の半導体装置［２００］の直列接続点をＡＣ入力［１０３，１０４］とする。二つのハーフブリッジ回路並びにＤＣリンクキャパシタ［２０１］の並列接続点が、ＤＣ出力として、ＤＣバス［１１０，１１１］に接続される。
【0028】
ＡＣ入力端子［１０３，１０４］に入力されるＡＣ電力が、ダイオードにより整流されて、ＤＣ電力に変換される。ＤＣ電力は、ＤＣリンクキャパシタ［２０１］を充電するとともに、ＤＣバス［１１０，１１１］に出力される。
【0029】
ＡＣ／ＤＣ変換回路［１０９］は、半導体スイッチング素子により、ＤＣバス［１１０，１１１］に入力されるＤＣ電力をＡＣ電力に変換してＡＣ入力［１０３，１０４］から出力できる。すなわち、ＡＣ／ＤＣ変換回路［１０９］は双方向電力変換回路として動作できる。
【0030】
図３は、ＡＣ／ＤＣ変換回路［１０９］の他の例を示す回路図である。
【0031】
図３に示すように、ＡＣ／ＤＣ変換回路［１０９］は、半導体スイッチング素子（図３では、ＩＧＢＴ）とダイオードが逆並列に接続された半導体装置［２００］が用いられるハーフブリッジ回路と、ＤＣリンクキャパシタ［２０１，２０２］の直列接続回路との、並列接続からなる。ハーフブリッジ回路における２個の半導体装置［２００］の直列接続点、および二つのＤＣリンクキャパシタ［２０１］の直列接続点を、それぞれ、ＡＣ入力［１０３，１０４］とする。ハーフブリッジ回路の両端、すなわちＤＣリンクキャパシタ［２０１，２０２］の直列接続回路の両端が、ＤＣとして、ＤＣバス［２０１，２０２］に接続される。
【0032】
ＡＣ入力［１０３，１０４］に入力されるＡＣ電力が、ダイオードにより整流されて、ＤＣ電力に変換される。ＤＣ電力は、ＡＣ入力電圧の極性に応じて、ＤＣリンクキャパシタ［２０１，２０２］を交互に充電する。
【0033】
図３に示すＡＣ／ＤＣ変換回路［１０９］は、半導体スイッチング素子により、ＤＣ出力端子［１１０，１１１］に入力されるＤＣ電力をＡＣ電力に変換してＡＣ入力端子［１０３，１０４］から出力できる。すなわち、ＡＣ／ＤＣ変換回路［１０９］は双方向電力変換回路として動作できる。
【0034】
図４は、ＤＣ／ＤＣ変換回路［１１２］の一例を示す回路図である。
【0035】
図４に示すように、ＤＣ／ＤＣ変換回路［１１２］は、絶縁型であり、ＤＣ／ＡＣ変換回路［３００］と、高周波トランス［３１０］を介してＤＣ／ＡＣ変換回路［３００］に接続されるＡＣ／ＤＣ変換回路［４００］とを有する。
【0036】
ＤＣ／ＡＣ変換回路［３００］は、半導体スイッチング素子（図４では、ＩＧＢＴ）とダイオードが逆並列に接続された半導体装置［３０１］が用いられる単相フルブリッジ回路と、単相フルブリッジ回路に並列に接続される一次側キャパシタ［３１１］とからなる。
【0037】
二つのハーフブリッジ回路並びに一次側キャパシタ［３１１］の並列接続点が、ＤＣ入力として、ＤＣバス［１１０，１１１］に接続される。各ハーフブリッジ回路における２個の半導体装置［３０１］の直列接続点が、ＡＣ出力として、高周波トランス［３１０］の一次巻線［３０５］にリアクトル［３０３］を介して接続される。
【0038】
ＡＣ／ＤＣ変換回路［４００］は、半導体スイッチング素子（図４では、ＩＧＢＴ）とダイオードが逆並列に接続された半導体装置［３１２］が用いられる単相フルブリッジ回路と、単相フルブリッジ回路に並列に接続される二次側キャパシタ［３１３］とからなる。
【0039】
各ハーフブリッジ回路における２個の半導体装置［３１２］の直列接続点が、ＡＣ入力として、高周波トランス［３１０］の二次巻線［３０８］に接続される。二つのハーフブリッジ回路並びに一次側キャパシタ［２０１］の並列接続点が、ＤＣ出力として、ＤＣバス［１１３，１１４］に接続される。
【0040】
ＤＣ／ＡＣ変換回路［３００］は、半導体スイッチング素子により、ＤＣバス［１１０，１１１］から入力するＤＣ電力を、ＡＣ電力に変換して、高周波トランス［３１０］の一次巻線［３０５］に出力する。高周波トランス［３１０］は、一次巻線［３０５］で受けたＡＣ電力を、ＡＣ電圧を降圧もしくは昇圧して、二次巻線［３０８］に出力する。
【0041】
ＡＣ入力端子［１０３，１０４］に入力されるＡＣ電力が、ダイオードにより整流されて、ＤＣ電力に変換される。ＤＣ電力は、ＤＣリンクキャパシタ［２０１］を充電するとともに、ＤＣバス［１１０，１１１］に出力される。
【0042】
ＡＣ／ＤＣ変換回路［４００］は、二次巻線［３０８］から入力するＡＣ電力をダイオードにより整流して、ＤＣ電力に変換する。ＤＣ電力は、二次側キャパシタ［３１３］を充電するとともに、ＤＣバス［１１０，１１１］ヘ出力される。
【0043】
ＡＣ／ＤＣ変換回路［４００］は、半導体スイッチング素子により、ＤＣバス［１１０，１１１］から入力されるＤＣ電力をＡＣ電力に変換できる。ＤＣ／ＡＣ変換回路［３００］は、高周波トランス［３１０］を介してＡＣ／ＤＣ変換回路［４００］から入力されるＡＣ電力を、ダイオードによりＤＣ電力に変換できる。なわち、ＤＣ／ＤＣ変換回路［１１２］は双方向電力変換回路として動作できる。
【0044】
図５は、制御ユニット［１２８］の構成を示すブロック図である。
【0045】
図５に示すように、第１制御部［４０１］と第２制御部［４０２］とからなる。
【0046】
第１制御部［４０１］は、電圧もしくは電流基準値［１３１］とＥＶ側情報［１３３］（ＳＯＣ，ユーザ設定情報）に基づいて、コンバータセル［１２８］の出力電流指令［４００］と、マトリクススイッチ［１２０］における各開閉器の開閉状態（ＯＮ，ＯＦＦ）を設定するマトリクススイッチ制御指令［４０３］を作成する。
【0047】
第２制御部［４０２］は、第１制御部［４０１］よって作成される出力電流指令［４００］および出力電流指令［４００］、並びに充電装置［１２７］における電圧および電流情報［１２９］に基づいて、コンバータセル［１０８］およびマトリクススイッチ［１２０］に対する駆動信号［１３０］を作成する。例えば、駆動信号［１３０］は、マトリクススイッチ［１２０］における開閉器へのオン・オフ駆動信号、並びにコンバータセル［１０８］における半導体スイッチング素子へのゲート駆動信号である。
【0048】
図６は、制御ユニット［１２８］の動作を示すフローチャートである。なお、制御ユニット［１２８］は、マイクロコンピュータなどのコンピュータシステムを有し、コンピュータシステムが所定のプログラムを実行することにより、制御動作を行う。
【0049】
ステップＳ０で、制御ユニット［１２８］は、制御動作を開始する。
【0050】
次に、ステップＳ１において、制御ユニット［１２８］は、ＥＶ側情報［１３３］に基づいて、複数（ｎ台）のＥＶ用充電ポート［１２２］（充電スタンド）におけるＥＶの接続状態を検査する。
【0051】
次に、ステップＳ２において、制御ユニット［１２８］は、ＥＶ側情報［１３３］に基づいて、ＥＶ用充電ポート［１２２］（充電スタンド）に接続されたＥＶが要する充電電力を、確認もしくは算出する。
【0052】
次に、ステップＳ３において、制御ユニット［１２８］は、ＥＶ側情報［１３３］に基づいて、マトリクススイッチにおける、複数（ｍ個）の入力ポート（コンバータユニット［１１６］側）と複数（ｎ個）の出力ポート（ＥＶ用充電ポート［１２２］側）との間の接続構成を設定する。すなわち、制御ユニット［１２８］は、第一制御部［４０１］（図２）を用いて、マトリクススイッチ制御指令［４０３］を作成する。
【0053】
次に、ステップＳ４において、制御ユニット［１２８］は、高電圧（ＨＶ）側キャパシタ、すなわちＤＣバス［１１０，１１１］に接続されるＤＣリンクキャパシタ［２０１］（図２）もしくは一次側キャパシタ［２０１］（図４）において、許容される最大電圧およびリップルのピーク・ピーク値、すなわち許容電圧変動範囲と、ステップＳ２の実行結果に応じて各コンバータセル［１０８］に要求される出力電力に基づいて、個々のＥＶに対する充電電流の範囲、すなわち最大値（Ｉｒｅｆ＿ｍａｘ）、最小値（Ｉｒｅｆ＿ｍｉｎ）および平均値（Ｉｒｅｆ＿ａｖｇ（＝（Ｉｒｅｆ＿ｍａｘ＋Ｉｒｅｆ＿ｍｉｎ）／２））を算出する。
【0054】
次に、ステップＳ６において、制御ユニット［１２８］は、ユーザ設定情報（充電スピードなど）に対応する充電電流ユーザ設定値（Ｉｒｅｆ＿ｕｓｅｒ）が、ステップＳ４で算出した充電電流の範囲内（Ｉｒｅｆ＿ｍｉｎ≦Ｉｒｅｆ＿ｕｓｅｒ≦Ｉｒｅｆ＿ｍａｘ）であるかを判定する。なお、制御ユニット［１２８］は、ユーザ設定情報（充電スピードなど）に対応する充電電流ユーザ設定値（Ｉｒｅｆ＿ｕｓｅｒ）を、予め記憶している、ユーザ設定情報と充電電流ユーザ設定値との関係から抽出する（ステップＳ５）。
【0055】
制御ユニット［１２８］は、充電電流ユーザ設定値（Ｉｒｅｆ＿ｕｓｅｒ）がステップＳ４で算出した充電電流の範囲内（Ｉｒｅｆ＿ｍｉｎ≦Ｉｒｅｆ＿ｕｓｅｒ≦Ｉｒｅｆ＿ｍａｘ）であると判定すると（ステップＳ６のＹｅｓ）、次に、ステップＳ７を実行する。また、制御ユニット［１２８］は、充電電流ユーザ設定値（Ｉｒｅｆ＿ｕｓｅｒ）がステップＳ４で算出した充電電流の範囲内（Ｉｒｅｆ＿ｍｉｎ≦Ｉｒｅｆ＿ｕｓｅｒ≦Ｉｒｅｆ＿ｍａｘ）にはないと判定すると（ステップＳ６のＮｏ）、次に、ステップＳ８を実行する。
【0056】
ステップＳ７において、制御ユニット［１２８］は、充電電流の値を充電電流ユーザ設定値（Ｉｒｅｆ＿ｕｓｅｒ）に設定する。
【0057】
ステップＳ８において、制御ユニット［１２８］は、充電電流の値を平均値（Ｉｒｅｆ＿ａｖｇ（＝（Ｉｒｅｆ＿ｍａｘ＋Ｉｒｅｆ＿ｍｉｎ）／２））に設定する。
【0058】
次に、ステップＳ９において、制御ユニット［１２８］は、ステップＳ７，Ｓ８に応じて、コンバータセル［１０８］に対して充電電流指令値を設定する。すなわち、制御ユニット［１２８］は、第１の制御部［４０１］（図２）を用いて、出力電流指令［４００］（図２）を生成する。
【0059】
次に、ステップＳ１０において、制御ユニット［１２８］は、ＥＶ側情報［１３３］に基づいて、ＥＶ接続解除、または充電終了、もしくは他のＥＶの追加接続に関する要求の有無を判定する。制御ユニット［１２８］は、要求有と判定すると（ステップＳ１０のＹｅｓ）、次に、ステップＳ１１を実行する。また、制御ユニット［１２８］は、要求無と判定すると（ステップＳ１０のＮｏ）、ステップＳ４以降を再度実行する。
【0060】
ステップＳ１１において、制御ユニット［１２８］は、充電装置［１２７］が用いている複数（ｍ台）のコンバータユニット［１１６］の各々の出力電流が低減するように、出力電流指令［４００］（図２）を変更する。このとき、制御ユニット［１２８］は、各コンバータユニット［１１６］において並列接続されている複数（三相分）のコンバータセル［１０８］を、各コンバータセル［１０８］の出力電流が低減されるように制御する。
【0061】
本発明者の検討によれば、変更後の出力電流指令は、キャパシタ（図２，３における２０１，２０２、図４における３１１）が接続されるＤＣバス［１１０，１１１］の電圧のアンバランスが、ＤＣバス電圧の基準値（例えば、ＡＣ電源電圧／ｍ）の３０％未満となるように設定されることが好ましい。例えば、高電圧キャパシタ（図２，３における２０１，２０２、図４における３１１）電圧リプルが基準値の３０％未満に保たれるようにする。なお、変更後の出力電流指令は、零もしくは零に近い所定値でもよい。
【0062】
次に、ステップＳ１２において、制御ユニット［１２８］は、ＥＶの新規接続や接続解除に伴い、マトリクススイッチにおける、複数（ｍ個）の入力ポート（コンバータユニット［１１６］側）と複数（ｎ個）の出力ポート（ＥＶ用充電ポート［１２２］側）との間の接続構成を再設定する。
【0063】
次に、ステップＳ１３において、制御ユニット［１２８］は、所定の遅延時間の後、再度ステップＳ１以降を実行する。遅延時間は、ＥＶの新規接続や接続解除に伴うコンバータユニット［１１６］およびコンバータセル［１０８］における電圧・電流の過渡的な変動がおさまるのに要する時間（例えば、１μｓｅｃ以上）に設定される。
【0064】
図６中のモードI，II，IIIについては、後述する。
【0065】
図７は、制御ユニット［１２８］の動作モード（I，II，III）の遷移を示すタイムチャートである。
【0066】
モードIは、図６のフローチャートにおけるステップＳ０～Ｓ９の動作に相当する。すなわち、モードIは、動作開始直後における、各コンバータセル［１０８］への充電電流指令値設定動作である。
【0067】
モードIIは、図６のフローチャートにおけるステップＳ１０～Ｓ１３の動作に相当する。すなわち、動作モードIIは、ＥＶの接続状態を変化させるときに、各コンバータセル［１０８］の出力電流指令値を最小レベルに設定し、それからマトリクススイッチ［２００］における入出力ポートの接続状態を再構成する動作である。
【0068】
モードIIIは、図６のフローチャートにおけるステップＳ１～Ｓ１９の動作に相当する。すなわち、動作モードIは、動作開始以降における、各コンバータセル［１０８］への充電電流指令値設定動作である。
【0069】
図７に示すように、制御ユニット［１２８］は、動作開始時点（ｔ０）でまず動作モードIにて動作する。ＥＶの接続状態の変化に関する要求があると（ｔ１）、動作モードは、モードIIへ遷移する。
【0070】
モードIIでは、図６（ステップＳ１３）に示すように、所定の遅延時間が設定される。したがって、モードIIの時間幅は遅延時間を含む一定値となる。
【0071】
モードIIが終了すると（ｔ２）、動作モードは、モードIIIへ遷移する。以後（ｔ３以降）、動作モードは、モードIIとモードIIIを交互に繰り返す。
【0072】
期間ｔ０－ｔ１の間、ＥＶ充電ポート１～ｍに接続されたＥＶが充電を開始し、バッテリー電圧が上昇する。ｔ１の時点（モードIIの開始）で、ＥＶ充電ポート１は、ＥＶ充電ポート１でＥＶ充電を停止するコマンドを制御ユニット［１２８］から受け取る。したがって、コントロールユニット［１２８］は、安全なＥＶ切断のために、基準電流コマンドをすべてのコンバータユニット［１１６］に送ってゼロにする。ｔ１－ｔ２の間に、すべてのコンバータ電流はゼロに減少する。電流がゼロになった後、ＥＶはＥＶ充電ポート１から切り離されるが、それ以外のポートは接続されたままである。したがって、ＥＶ電圧は、ｔ２－ｔ３の間、接続ポートに反映される。この時間間隔の間、ＥＶ充電ポート１に接続されたコンバータユニット［１１６］は、ＥＶがまだマトリックススイッチ［１２０］で接続されている他の利用可能なポートの一つと再接続される。ｔ３～ｔ４の間、ＥＶ充電ポートｍと他のポートはコンバータユニット開始する。なお、ＥＶ充電ポート［１２２］の電圧波形と電流波形を示している。
【0073】
次に、マトリクススイッチ［１２０］における入出力ポートの接続状態の再構成の例について説明する。
【0074】
図８は、ＥＶが搭載する蓄電池を充電する場合における、マトリクススイッチ［１２０］における入出力ポートの接続状態の一例を示す回路図である。図中、電力の伝送経路を矢印で示す。なお、以下で説明する図８に記載されるマトリクススイッチ［１２０］の構成は、図９～１１に記載されるマトリクススイッチ［１２０］も同様である。
【0075】
マトリクススイッチ［１２０］は、ｍ行ｎ列のマトリクス状に配置される複数（ｍ×ｎ個）の開閉器［７００（１，１）～７００（ｍ，ｎ）］を有している。マトリクススイッチ［１２０］は、複数（ｍ台）のコンバータユニット［１１６］の複数（ｍ個）のＤＣ出力［１１５］が電気的に接続される複数（ｍ個）の入力ポート［１１５（１）～１１５（ｍ）］を有する。また、マトリクススイッチ［１２０］は、複数（台）のコンバータユニット［１１６］の複数（ｍ個）のＤＣ出力［１１５］が電気的に接続される複数（ｍ個）の入力ポート［１１５（１）～１１５（ｍ）］を有する。また、複数（ｎ個）の接続ケーブル［１２１］が電気的に接続される複数（ｎ個）の出力ポート［１２１（１）～１２１（ｎ）］を有する。
【0076】
マトリクススイッチ［１２０］において、入力ポート［１１５（１）～１１５（ｍ）］は、それぞれバス［７０１（１）～７０１（ｍ）］に接続され、そして、出力ポート［１２１（１）～１２１（ｎ）］はバス［７０２（１）～７０２（ｎ）］に接続される。開閉器［７００（ｍ，ｎ）］は、バス［７０１（ｍ）］とバス［７０２（ｎ）］との間に接続される。
【0077】
図８に示すように、ｎ台のＥＶ［１２４］が、出力ポート１２１（１），１２１（２），１２１（ｎ）に接続される。
【0078】
出力ポート１２１（１）に接続されるＥＶ［１２４］には、入力ポート１１５（１）に接続されるコンバータユニット［１１６］の出力電力が、バス［７０１（１）］→開閉器［７００（１，１）］→バス［７０２（１）］という経路で、伝送される。これにより、出力ポート１２１（１）に接続されるＥＶ［１２４］に搭載される蓄電池が充電される。
【0079】
出力ポート１２１（２）に接続されるＥＶ［１２４］には、入力ポート１１５（２）に接続されるコンバータユニット［１１６］の出力電力が、バス［７０１（２）］→開閉器［７００（２，２）］→バス［７０２（２）］という経路で、伝送される。これにより、出力ポート１２１（２）に接続されるＥＶ［１２４］に搭載される蓄電池が充電される。
【0080】
出力ポート１２１（ｎ）に接続されるＥＶ［１２４］には、入力ポート１１５（ｍ）に接続されるコンバータユニット［１１６］の出力電力が、バス［７０１（ｍ）］→開閉器［７００（ｍ，ｎ）］→バス［７０２（ｎ）］という経路で、伝送される。これにより、出力ポート１２１（ｎ）に接続されるＥＶ［１２４］に搭載される蓄電池が充電される。
【0081】
図９は、ＥＶが搭載する蓄電池を充電する場合における、マトリクススイッチ［１２０］における入出力ポートの接続状態の再構成例を示す回路図である。図中、電力の伝送経路を矢印で示す。
【0082】
【0083】
図８の接続状態において、出力ポート１２１（ｎ）に接続されるＥＶ［１２４］の切り離しの要求がある場合、前述のようにコンバータセル［１０８］の出力電流指令値が低減される。それから、マトリクススイッチの接続状態が再構成されて、図９の接続状態に遷移する。このため、ＤＣバス［１１０，１１１］の電圧アンバランスの大きさを抑制できる。
【0084】
図９に示すように、３台のＥＶ［１２４］の内、図８において出力ポート［１２１（ｎ）］に接続されているＥＶ［１２４］が、出力ポート１２１（ｎ）から切り離される。このとき、開閉器［７００（ｍ，ｎ）］がオフする。
【0085】
開閉器［７００（ｍ，ｎ）］のオフに伴い、出力ポート［１２１（ｎ）］に接続されているＥＶ［１２４］への電力伝送が遮断される。このとき、ＤＣバス［１１０，１１］の電圧のアンバランスが生じ得るが、各コンバータセル［１１６］の出力電流が低減されているため、電圧アンバランスの大きさが抑制される。
【0086】
なお、本実施形態では、開閉器［７００（ｍ，２）］をオンすることにより、入力ポート［１１５（ｍ）］に接続されるコンバータユニット［１１６］の出力電力が、出力ポート［１２１（２）］への接続が維持されているＥＶ［１２４］へ充電される。すなわち、入力ポート［１１５（ｍ）］に接続されるコンバータユニット［１１６］の出力電力の伝送が継続する。これにより、出力ポート１２１（ｎ）からのＥＶ［１２４］の切り離しに伴うＤＣバス［１１０，１１］の電圧アンバランスの発生が抑制される。
【0087】
図１０は、ＥＶが搭載する蓄電池を放電する場合における、マトリクススイッチ［１２０］における入出力ポートの接続状態の一例を示す回路図である。図中、電力の伝送経路を矢印で示す。
【0088】
ＡＣ／ＤＣ変換回路［１０９］およびＤＣ／ＤＣ変換回路［１１２］は共に双方向型の電力変換回路であるため、ＥＶ［１２４］に搭載される蓄電池の充電および放電が可能である。
【0089】
図１０に示すように、３台のＥＶ［１２４］が、出力ポート１２１（１），１２１（２），１２１（ｎ）に接続される。
【0090】
出力ポート１２１（１）に接続されるＥＶ［１２４］の蓄電電力が、入力ポート１１５（１）に接続されるコンバータユニット［１１６］へ、バス［７０２（１）］→開閉器［７００（１，１）］→バス［７０１（１）］という経路で、伝送される。これにより、出力ポート１２１（１）に接続されるＥＶ［１２４］に搭載される蓄電池が放電される。
【0091】
出力ポート１２１（２）に接続されるＥＶ［１２４］の蓄電電力が、入力ポート１１５（２）に接続されるコンバータユニット［１１６］へ、バス［７０２（２）］→開閉器［７００（２，２）］→バス［７０１（２）］という経路で、伝送される。これにより、出力ポート１２１（２）に接続されるＥＶ［１２４］に搭載される蓄電池が放電される。
【0092】
出力ポート１２１（ｎ）に接続されるＥＶ［１２４］の蓄電電力は、入力ポート１１５（ｍ）に接続されるコンバータユニット［１１６］へ、バス［７０２（ｎ）］→開閉器［７００（ｍ，ｎ）］→バス［７０１（ｍ）］という経路で、伝送される。これにより、出力ポート１２１（ｎ）に接続されるＥＶ［１２４］に搭載される蓄電池が充電される。
【0093】
図１１は、ＥＶが搭載する蓄電池を放電する場合における、マトリクススイッチ［１２０］における入出力ポートの接続状態の再構成例を示す回路図である。図中、電力の伝送経路を矢印で示す。
【0094】
【0095】
図１０の接続状態において、出力ポート１２１（ｎ）に接続されるＥＶ［１２４］の切り離しの要求がある場合、前述のようにコンバータセル［１０８］の出力電流指令値が低減される。それから、マトリクススイッチの接続状態が再構成されて、図１０の接続状態に遷移する。このため、ＤＣバス［１１０，１１１］の電圧アンバランスの大きさを抑制できる。
【0096】
図１１に示すように、３台のＥＶ［１２４］の内、図１０において出力ポート［１２１（ｎ）］に接続されているＥＶ［１２４］が、出力ポート１２１（ｎ）から切り離される。このとき、開閉器［７００（ｍ，ｎ）］がオフする。
【0097】
開閉器［７００（ｍ，ｎ）］のオフに伴い、出力ポート［１２１（ｎ）］に接続されているＥＶ［１２４］からの電力伝送が遮断される。このとき、ＤＣバス［１１０，１１］の電圧のアンバランスが生じ得るが、各コンバータセル［１０８］の出力電流が低減されているため、電圧アンバランスの大きさが抑制される。
【0098】
なお、本実施形態では、開閉器［７００（ｍ，２）］をオンすることにより、出力ポート［１２１（２）］への接続が維持されているＥＶ［１２４］の蓄電電力が、入力ポート［１１５（ｍ）］に接続されているコンバータセル［１０８］へ放電される。すなわち、入力ポート［１１５（ｍ）］に接続されているコンバータセル［１０８］への電力の伝送が継続する。これにより、出力ポート１２１（ｎ）からのＥＶ［１２４］の切り離しに伴うＤＣバス［１１０，１１］の電圧のアンバランスの発生が抑制される。
【0099】
なお、本発明は、他の実施態様が可能であり、様々な手段で実行または実施されるので、本発明は、添付図面に図示されている詳細な部分的構造および配置を適用するものに限定されないことを理解されたい。また、本明細書において用いられる語句または用語は、説明の目的で用いられるものであり、これらに限定するものではないことを理解されたい。
【0100】
例えば、ＥＶに搭載される蓄電装置は、蓄電池のほか、キャパシタでもよい。
【0101】
例えば、ＡＣ／ＤＣ変換回路［１０９］やＤＣ／ＤＣ変換回路［１１２］を構成する半導体スイッチング素子は、ＩＧＢＴに限らず、ＭＯＳＦＥＴや接合形バイポーラトランジスタなどでもよい。また、半導体スイッチング素子やダイオードを構成する半導体材料は、Ｓｉに限らず、ＳｉＣやＧａＮなどのワイドギャップ半導体でもよい。
【符号の説明】
【0102】
１００ ＡＣ電源
１０２ 三相リアクトル
１０３，１０４ ＡＣ入力端子
１０８ コンバータセル
１０９ ＡＣ／ＤＣ変換回路
１１０，１１１ ＤＣバス
１１２ ＤＣ／ＤＣ変換回路
１１３，１１４ ＤＣ出力端子
１１５ ＤＣバス
１２０ マトリクススイッチ
１２１ 接続ケーブル
１２２ ＥＶ用充電ポート（充電スタンド）
１２４ ＥＶ
１２５ 充電用ケーブル
１２７ 充電装置
１２８ 制御ユニット
１２９ 電圧および電流情報
１３０ 駆動信号
１３１ 電圧もしくは電流基準値
１３３ ＥＶ側情報
３１０ 高周波トランス
３００ ＤＣ／ＡＣ変換回路
４００ ＡＣ／ＤＣ変換回路
１０２ 三相リアクトル
１０３，１０４ ＡＣ入力端子
１０８ コンバータセル
１０９ ＡＣ／ＤＣ変換回路
１１０，１１１ ＤＣバス
１１２ ＤＣ／ＤＣ変換回路
１１３，１１４ ＤＣ出力端子
１１５ ＤＣバス
１２０ マトリクススイッチ
１２１ 接続ケーブル
１２２ ＥＶ用充電ポート（充電スタンド）
１２４ ＥＶ
１２５ 充電用ケーブル
１２７ 充電装置
１２８ 制御ユニット
１２９ 電圧および電流情報
１３０ 駆動信号
１３１ 電圧もしくは電流基準値
１３３ ＥＶ側情報
３１０ 高周波トランス
３００ ＤＣ／ＡＣ変換回路
４００ ＡＣ／ＤＣ変換回路
【図1】
【図2】
【図3】
【図4】
【図5】
【図6】
【図7】
【図8】
【図9】
【図10】
【図11】
【外国語明細書】
Description
Title of the Invention: Charging Device
Technical field
The present invention relates to a charging device for supplying charging power to a power storage device such as a storage battery.
Background Art
Recently, a charging device having a medium or high voltage isolated AC/DC converter is being applied with an increase in capacity of the charging device for an electric vehicle. Incidentally, hereinafter, "electric vehicle" will be described as "EV".
As a prior art relating to a charging device having a medium or high voltage isolated AC/DC converter, the technique described in Patent Document 1 is known.
In the technique described in Patent Document 1, AC inputs of a plurality of converter cells each comprising an isolated AC/DC converter are connected in series with each other. The AC inputs connected in series are directly connected to a high voltage AC power supply system without a transformer.
Each converter cell includes a AC/DC converting circuit having an AC input, a smoothing capacitor connected to the DC side of AC/DC converting circuit, an DC/AC converting circuit of which DC side is connected to the DC side of AC/DC converting circuit, a high-frequency transformer of which primary winding is connected to the AC side of DC/AC converting circuit and a AC/DC converting circuit of which AC side is connected to the secondary winding of the high-frequency transformer and that has a DC output.
The DC outputs of a plurality of converter cells are connected to a plurality of input ports of a switch unit. In the switch unit, between the plurality of input ports and the plurality of output ports, switches are connected in a matrix. Therefore, by operating the switch unit, the DC output of each converter cell is connected to an arbitrary output port. Each converter cell supplies DC power to a storage battery of an electric vehicle, which is a load connected to the output port, to charge the storage battery.
Citation List
Patent Literature
Patent Literature 1: WO2019/234988A1
Summary of Invention
Technical Problem
In the above prior art, when the connection state of the load in the plurality of output ports is changed, imbalance occurs in the DC voltage of the plurality of smoothing capacitors. When the imbalance occurs, the circuit may fail.
Therefore, the present invention provides a charging device capable of suppressing the voltage imbalance even if the connection state of the load varies.
Solution to problem
In order to solve the above problems, a charging device according to present invention, which charges a plurality of power storage devices, comprises a plurality of converter units for inputting AC power and outputting DC power, a matrix-switch having a plurality of input ports to which a plurality of outputs of the plurality of the converter units are connected and a plurality of output ports to which the plurality of the power storage devices are connected and a control unit controlling output current of the plurality of the converter units and a plurality of switches in the matrix-switch. Each of the plurality of the converter units has a converter cell including an AC/DC converting circuit for inputting the AC power and a DC/DC converting circuit, which is connected to the AC/DC converting circuit via a capacitor, outputting the DC power. A plurality of AC input terminals of the plurality of AC/DC converting circuit are connected in series with each other. The control unit reduces the output current of the plurality of converter units to a predetermined value when connecting the power storage device to the output port, or when disconnecting the power storage device from the output port, and thereafter, the control unit reconfigures a connection state between the plurality of the input ports and the plurality of the output ports in the matrix-switch.
Advantageous Effect of Invention
According to the present invention, it is possible to suppress the imbalance of the voltage.
Other problems, features and effects other than those described above will be clarified by the following description of the embodiment.
Brief Description of Drawings
Fig. 1 is a block diagram showing the configuration of a charging device for an electric vehicle as an embodiment of the present invention.
FIG. 2 is a circuit diagram illustrating an exemplary AC/DC converting circuit [109].
Fig. 3 is a circuit diagram showing another example of AC/DC converting circuit [109].
Fig. 4 is a circuit diagram illustrating an exemplary DC/DC converting circuit [112].
Fig. 5 is a block diagram showing a configuration of a control unit [128].
Fig. 6 is a flowchart showing the operation of the control unit [128].
Fig. 7 is a time chart showing the transitions of the operation mode (I, II, III) of the control unit [128].
Fig. 8 is a circuit diagram showing an example of a connection state of the input and output ports in the matrix-switch [120] in the case of charging the storage battery mounted on the EV [124].
Fig. 9 is a circuit diagram showing a reconfiguration example of the connection state of the input and output ports in the matrix-switch [120] in the case of charging the storage battery mounted on the EV [124].
Fig. 10 is a circuit diagram showing an example of a connection state of the input and output ports in the matrix-switch [120] in the case of discharging the storage battery mounted on the EV [124].
Fig. 11 is a circuit diagram showing a reconfiguration example of the connection state of the input and output ports in the matrix-switch [120] when discharging the storage battery mounted on the EV [124].
Description of Embodiment
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In each Figure, the same reference numerals denote components having the same or similar functions.
Fig. 1 is a block diagram showing the configuration of a charging device for an electric vehicle as an embodiment of the present invention.
A charging device [127] includes a three-phase four-wire AC power source [100], a plurality (m) of converter units [116] for inputting three-phase AC power through a three-phase reactor [102]. “m” is an integer not smaller than 2. Each converter unit [116] has three converter cells [108] for three phases to input single-phase AC power from one phase of AC power supply [100]. Each converter cell [108] includes an AC/DC converting circuit [109] for converting a single phase AC power into DC power and a DC/DC converting circuit [112] for converting the DC power output by AC/DC converting circuit [109] into DC power having different voltage. DC output terminals of the AC/DC converting circuit [109] are connected to the DC input terminals of the DC/DC converting circuit [112] by a DC bus [110, 111].
In a plurality (m) of the converter units [116], AC inputs for one phase among the three converter cells [108] for the three phases provided in each converter unit [116] are connected in series with each other. That is, AC input terminals [103,104] of each of the plurality (m) of the AC/DC converting circuits [109] are connected in series with each other. One end and the other end [106] of the series connection of the AC input terminals are respectively connected to one phase of the AC power supply [100] (e.g., U-phase) and the neutral point N of the AC power supply [100]. This allows the input of the converter cell [108] to be directly connected to a high voltage (e.g., 6.6kV or 11kV) AC power source [100] without a transformer.
The DC outputs of three converter cells [108] for three phases provided in each converter unit [116] are connected in parallel to each other. That is, the DC-output terminals [113,114] of the three DC/DC converting circuits [112] for the three-phases are connected in parallel. Thus, the DC output of each converter unit [116] is configured.
A matrix-switch [120] has a plurality (m) of input ports and a plurality (n) of output ports. “n” is an integer not smaller than 2. The matrix-switch [120] has m × n switches arranged in a matrix of m rows and n columns between a plurality (m) of input ports and a plurality (n) of output ports. Each DC output of a plurality (m) of the converter units [116] is connected to a different input port among a plurality (m) of input ports via a DC bus [115]. By operating these switches, each input port and an arbitrary output port is electrically connected.
Incidentally, as the switch in the matrix-switch [120], electromagnetic or electronic switches are applied.
Each of the plurality (n) of the output ports of the matrix-switch [120] is electrically connected to an EV charging port [122] (charging stand) through a connection cable [121]. Each of the plurality (n) of the EV charging ports [122] (charging stands) is connected to an EV [124] through a charging cable [125].
When the matrix-switch [120] is operated and any DC output of the plurality (m) of the converter units [116] is connected, the DC power output by the converter unit [116] is charged in the storage battery mounted on the EV [124]. By controlling the plurality of switches in the matrix-switch [120], the DC output of the converter unit [116] is connected to the EV [124] or disconnected from the EV [124]. Further, in the case of such high-speed charging, DC outputs of a plurality (e.g., two) of the converter units [116] can be connected to a single EV with opening and closing control of the matrix-switch [120].
A control unit [128] generates a drive signal [130] to the matrix-switch [120] and each converter cell [108] for opening and closing control of the matrix-switch [120] and DC output power control of each converter cell [108] based on voltage and current information [129] in the charging device [127], a voltage or current reference value [131], and EV-side information [133] from a charging port group [132] including a plurality of the EV charging ports [122] (charging stands).
In the present embodiment, the voltage and current information [129] includes a voltage [117] of a DC bus [110, 111] that connects AC/DC converting circuit [109] and DC/DC converting circuit [112] in each converter cell [108], and a voltage and current [118] in the DC output [115] of each converter unit [116]. Voltage and current information [129] are detected by voltage and current sensors, respectively.
Further, in the present embodiment, the EV-side information [133] includes SOC information [123] relating to the state of charge (SOC) of the storage battery of the EV, user setting information such as the charging speed (low speed, medium speed, high speed), and EV connection information relating to the connection and disconnection of the EV [124] to the EV charging port [122] (charging stand). The SOC information [123] is transmitted to the control unit [128] via a communication line provided in the charging cable [125] and via the EV charging port [122] (charging stand). User setting information is set with switch operation or button operation of the EV charging port [122] (charging stand)]. The EV connection information is detected by the EV charging port [122] (charging stand). User setting information and EV connection information are transmitted to the control unit [128] by the EV charging port [122] (charging stand).
FIG. 2 is a circuit diagram illustrating an exemplary AC/DC converting circuit [109].
As shown in FIG. 2, AC/DC converting circuit [109] includes a single-phase full-bridge circuit using a semiconductor device [200] which includes a semiconductor switching element (in FIG. 2, IGBT) and a diode connected each other in anti-parallel and a DC link capacitor [201] connected in parallel to the single-phase full-bridge circuit. The series connection point of the two semiconductor devices [200] in each half-bridge circuit is defined as the AC input [103,104]. The parallel connection points of the two half-bridge circuits and the DC link capacitor [201] are connected as DC outputs to the DC bus [110,111].
AC power input to the AC input terminal [103,104] is rectified by the diode and converted into DC power. The DC power is output to the DC bus [110,111] while charging the DC link capacitor [201].
The AC/DC converting circuit [109] can convert the DC power input to the DC bus [110,111] into AC power and output from the AC input [103,104] by the semiconductor switching element. That is, AC/DC converting circuit [109] can operate as a bidirectional power converting circuit.
Fig. 3 is a circuit diagram showing another example of AC/DC converting circuit [109].
As shown in Fig. 3, AC/DC converting circuit [109] has a parallel connection of a half-bridge circuit using the semiconductor device [200] which includes the semiconductor switching element (in Fig. 3, IGBT) and the diode connected each other in anti-parallel and a series connection circuit of DC link capacitors [201, 202].
The series connection points of the two semiconductor devices [200] in the half-bridge circuit and the series connection points of the two DC link capacitors [201, 202] are the AC input [103] and the AC input[104] respectively. Both ends of the half-bridge circuit, i.e., both ends of the series-connected circuit of the DC link capacitor [201,202], are connected DC to the DC bus [201,202].
The AC power input to the AC input [103,104] is rectified by a diode and is converted into DC power. The DC power alternately charges the DC link capacitor [201,202] according to the polarity of the AC input voltage.
The AC/DC converting circuit [109] shown in FIG. 3 can output from the AC input terminal [103,104] by converting the DC power input to the DC output terminal [110,111] to AC power with using the semiconductor switching element. That is, AC/DC converting circuit [109] can operate as a bidirectional power converting circuit.
Fig. 4 is a circuit diagram illustrating an exemplary DC/DC converting circuit [112].
As shown in Fig. 4 DC/DC converting circuit [112] is an isolated type and includes a DC/AC converting circuit [300] and an AC/DC converting circuit [400] connected to DC/AC converting circuit [300] via a high-frequency transformer [310].
DC/AC converting circuit [300] includes a single-phase full-bridge circuit using a semiconductor device [301] which includes a semiconductor switching element (in FIG. 4, IGBT) and a diode connected each other in anti-parallel and a primary capacitor [311] connected in parallel to the single-phase full-bridge circuit.
The parallel connection points of the two half-bridge circuits and the primary capacitor [311] are connected as DC inputs to the DC bus [110,111].
Series connection point of the two semiconductor devices [301] in each half-bridge circuit, as an AC output, is connected to the primary winding [305] of the high-frequency transformer [310] via a reactor [303].
AC/DC converting circuit [400] includes a single-phase full-bridge circuit using a semiconductor device [312] which includes a semiconductor switching element (in FIG. 4, IGBT) and a diode connected each other in anti-parallel and a secondary capacitor [313] connected in parallel to the single-phase full-bridge circuit.
The series connection point of the two semiconductor devices [312] in each half-bridge circuit, as an AC input, is connected to the secondary winding [308] of the high-frequency transformer [310]. The parallel connection points of the two half-bridge circuits as well as the secondary capacitor [313] are connected to DC bus [113,114] as DC outputs.
DC/AC converting circuit [300] converts the DC power input from the DC bus [110,111] into AC power by the semiconductor switching element, and outputs the DC power to the primary winding [305] of the high-frequency transformer [310]. The high-frequency transformer [310] step-down or step-up the AC voltage to output the AC power received by the primary winding [305] to the secondary winding [308].
AC power input to the AC input terminal [103,104] is rectified by a diode and converted into DC power. The DC power is output to the DC bus [110,111] while charging the DC link capacitor [201].
The AC/DC converting circuit [400] rectifies the AC power input from the secondary winding [308] by a diode and converts it into DC power. The DC power is output to the DC bus [110,111] while charging the secondary capacitor [313].
The AC/DC converting circuit [400] can convert the DC power input from the DC bus [113,114] into AC power by the semiconductor switching element. The DC/AC converting circuit [300] can convert AC power input from AC/DC converting circuit [400] via the high-frequency transformer [310] into DC power by a diode. Consequently, the AC/DC converting circuit [400] and DC/AC converting circuit [300] can operate as bidirectional power converting circuits.
Fig. 5 is a block diagram showing a configuration of a control unit [128].
As shown in Fig. 5, the control unit [128] has a first control unit [401] and a second control unit [402].
The first control unit [401] generates an output current command [400] of the converter cell [108] and a matrix-switch control command [403] for setting the switching states (ON and OFF) of the switches in the matrix-switch [120] based on the voltage or current reference value [131] and the EV-side information [133] (SOC, user setting information).
The second control unit [402] generates a drive signal [130] for the converter cell [108] and the matrix-switch [120] based on the output current command [400] generated by the first control unit [401] and the voltage and current information [129] in the charging device [127].
For example, the drive signal [130] is an on/off drive signal to the switches in the matrix-switch [120] and a gate drive signal to the semiconductor switching element in the converter cell [108].
Fig. 6 is a flowchart showing the operation of the control unit [128]. The control unit [128] includes a computer system such as a microcomputer, and performs a control operation when the computer system executes a predetermined program.
In step S0, the control unit [128] starts the control operation.
Next, in step S1, the control unit [128] checks the connection state of the EV [124] in the plurality (n) of the EV charging ports [122] (charging stands) based on the EV-side information [133].
Next, in step S2, the control unit [128] checks or calculates the charging power required by the EV [124] connected to the EV charging port [122] (charging stand) based on the EV-side information [133].
Next, in step S3, the control unit [128] sets a connection configuration between a plurality (m) of input ports (converter unit [116] side) and a plurality (n) of output ports (EV charging port [122] side) in the matrix-switch [120] based on the EV-side information [133]. That is, the control unit [128] generates a matrix-switch control command [403] with using the first control unit [401] (FIG. 2).
Next, in step S4, the control unit [128] calculates the range of the charging current for each EV [124], i.e., the maximum value (Iref_max), the minimum value (Iref_min), and the average value (Iref_avg(=(Iref_max+Iref_min)/2)) based on the allowable maximum voltage and the allowable peak-to-peak value of ripple, i.e., the allowable voltage variation range in the high voltage (HV) side capacitor, i.e., the DC link capacitor [201] (FIG. 2) or the primary side capacitor [311] (FIG. 4) connected to the DC bus [110, 111] and based on the output power required for each converter cell [108] according to the result of the execution of step S2.
Next, in step S6, the control unit [128] determines whether the charging current user set value (Iref_user) corresponding to the user setting information (such as the charging speed) is within the range of the charging current calculated in step S4 (Iref_min ≦ Iref_user ≦ Iref_max). Additionally, the control unit [128] extracts the charging current user set value (Iref_user) corresponding to the user setting information (such as the charging speed) from the relationship between the user setting information and the charging current user set value stored in advance (Step S5).
When the control unit [128] determines that the charging current user set value (Iref_user) is within the range of the charging current calculated in Step S4 (Yes in Step S6) (Iref_min ≦ Iref_user ≦ Iref_max), then the control unit [128] executes Step S7. When the control unit [128] determines that the charging current user set value (Iref_user) is not within the range of the charging current calculated in step S4 (Iref_min ≦ Iref_user ≦ Iref_max) (No in step S6) (Iref_min > Iref_user, Iref_user > Iref_max), then the control unit [128] executes step S8.
In step S7, the control unit [128] sets the value of the charging current to the charging current user set value (Iref_user).
In step S8, the control unit [128] sets the value of the charging current to the average value (Iref_avg (= (Iref_max + Iref_min))/2).
Next, in step S9, the control unit [128] sets the charging current command value to the converter cell [108] in accordance with steps S7 and S8. That is, the control unit [128] generates an output current command [400] (FIG. 2) with using the first control unit [401] (FIG. 2).
Next, in step S10, the control unit [128] determines whether or not there is a request relating to the EV disconnection, or the end of charging, or an additional connection of another EV, based on the EV-side information [133].
When the control unit [128] determines that there is a request (Yes in step S10), then the control unit [128] executes step S11. Further, when the control unit [128] determines that there is no request (No in Step S10), then the control unit [128] executes the steps S4 and subsequent steps again.
In step S11, the control unit [128] changes the output current command [400] so that the output current of each of the plurality (m) of converter units [116] used by the charging device [127] is reduced. At this time, the control unit [128] controls the plurality (three) of the converter cells [108] for three phases connected each other in parallel in each converter unit [116] so that the output current of each converter cell [108] is reduced.
According to the studies of the present inventors, it is preferable that the output current command after the change is set so that the imbalance of the voltage of the DC bus [110,111] to which the capacitor (201 and 202 in Fig. 2 and Fig. 3, 311 in Fig. 4) is connected is less than 30% of the reference value of the DC bus voltage (e.g., (AC power supply voltage)/m). For example, the high voltage capacitor (201 and 202 in Fig. 2 and Fig. 3, 311 in Fig. 4) voltage ripple is kept under 30% of the reference command value. The output current command after the change may be a predetermined value close to zero or zero.
Next, in step S12, the control unit [128] reconfigures a connection configuration between the plurality (m) of input ports and the plurality (n) of output ports in the matrix-switch [120] with the new connection and disconnection of the EV [124].
Next, in step S13, the control unit [128] executes step S1 and subsequent steps again after a predetermined delay time. The delay time is set to the time (e.g., 1 μsec or more) required to stop the transient fluctuation of the voltage and current in the converter unit [116] and the converter cell [108] associated with the new connection or disconnection of the EV.
Mode I, II, III in Fig. 6 will be described later.
Fig. 7 is a time chart showing the transitions of the operation mode (I, II, III) of the control unit [128].
Mode I corresponds to the operation of steps S0 to S9 in the flowchart of Fig. 6. That is, the mode I is a charging current command value setting operation to each converter cell [108] immediately after the start of operation.
Mode II corresponds to the operation of steps S10 to S13 in the flowchart of Fig. 6. That is, in the operation mode II, when changing the connection state of the EV, the output current command value of each converter cell [108] is set to the minimum level, and then the connection state of the input and output ports in the matrix-switch [200] is reconfigured.
Mode III corresponds to the operation of steps S1 to S19 in the flowchart of Fig. 6. That is, the operation mode I is the charging current command value setting operation to each converter cell [108] after the start of the operation.
As shown in Fig. 7, the control unit [128] operates first in the operation mode I at the operation start point (t0). When there is a request regarding the change of the connection state of the EV (t1), the operation mode changes to mode II.
In mode II, as shown in Fig. 6 (step S13), a predetermined delay time is set. Therefore, the time width of mode II becomes a constant value including the delay time.
When mode II ends (t2), the operation mode transitions to mode III. Hereafter (t3 onward), the operation mode repeats mode II and mode III alternately.
During period to-t1, EVs connected to the EV charging ports 1-m starts to charge and the battery voltage increases. As t1 instant (start of mode II), the EV charging port 1 receives a command from the control unit [128] to stop EV charging at the EV charging port 1. Hence, the control unit [128] sends reference current commands to all converter units [116] to make it to zero for safe EV disconnection. From t1-t2 time duration all converter currents reduce to zero. After current goes down to zero, the EV is disconnected from the EV charging port 1, however all other ports are still connected. So, the EV voltage will reflect at the connection ports for the time duration t2-t3. During this time interval, the converter unit [116] connected to the EV charging port 1 will be reconnected with one of the other available ports where the EV is still connected by the matrix-switch [120]. From t3-t4 time duration, the EV charging port m and other ports will again start the EV charging process. The voltage and current waveforms are shown for the EV charging ports [122].
Next, an example of reconfiguration of the connection state of the input and output ports in the matrix-switch [120] is described.
Fig. 8 is a circuit diagram showing an example of a connection state of the input and output ports in the matrix-switch [120] in the case of charging the storage battery mounted on the EV [124]. In the Figure, the transmission path of the power is indicated by an arrow. The configuration of the matrix-switch [120] in Fig. 8 described below is the same as that of the matrix-switch [120] described in Figs. 9 to 11.
The matrix-switch [120] has a plurality (m × n) of switches [700 (1, 1)-700 (m, n)] arranged in a matrix of m rows and n columns. The matrix-switch [120] has a plurality (m) of input ports [115(1)-115(m)] to which a plurality (m) of DC outputs [115] of a plurality (m) of the converter units [116] are electrically connected. Further, the matrix-switch [120] has a plurality (n) of output ports [121 (1)-121 (n)] which are electrically connected to a plurality (n) of connecting cables [121].
In the matrix-switch [120], input ports [115(1)-115(m)] are connected to buses [701(1)-701(m)], respectively, and output ports [121(1)-121(n)] are connected to buses [702(1)-702(n)]. The switch [700(m, n)] is connected between the bus [701(m)] and the bus [702(n)].
As shown in Fig. 8, n EVs [124] are connected to the output ports 121(1), 121(2), 121(n).
The output power of the converter unit [116] connected to the input port 115 (1) is transmitted to the EV [124] connected to the output port 121 (1) in a path, “bus [701 (1)] → switch [700 (1, 1)] → bus [702 (1)]. Thus, the storage battery mounted on the EV [124] connected to the output port 121 (1)” is charged.
The output power of the converter unit [116] connected to the input port 115 (2) is transmitted to the EV [124] connected to the output port 121 (2) in a path, “bus [701 (2)] → switch [700 (2, 2)] → bus [702 (2)]”. Thus, the storage battery mounted on the EV [124] connected to the output port 121 (2) is charged.
The output power of the converter unit [116] connected to the input port 115 (m) is transmitted to the EV [124] connected to the output port 121 (n) in a path, “bus [701 (m)] → switch [700 (m, n)] → bus [702 (n)]”. Thus, the storage battery mounted on the EV [124] connected to the output port 121 (n) is charged.
Fig. 9 is a circuit diagram showing a reconfiguration example of the connection state of the input and output ports in the matrix-switch [120] in the case of charging the storage battery mounted on the EV [124]. In the Figure, the transmission path of the power is indicated by an arrow.
Connection state in the matrix-switch transitions from the connection state shown in Fig.8 to the connection state shown in Fig.9.
In the connection state of Fig. 8, when there is a request for disconnection of the EV [124] connected to the output port 121 (n), the output current command value of the converter cell [108] is reduced as described above. Then, the connection state of the matrix-switch is reconfigured and transitions to the connection state of Fig.9.
Therefore, the magnitude of the voltage imbalance of the DC bus [110,111] can be suppressed.
As shown in Fig. 9, among the three EVs [124], the EV [124] connected to the output port [121 (n)] in FIG. 8 is disconnected from the output port 121 (n). At this time, the switch [700 (m, n)] is turned off.
With the switch [700(m, n)] off, the power transmission to the EV [124] connected to the output port [121(n)] is interrupted. At this time, the voltage imbalance of the DC bus [110, 11] may occur, but since the output current of each converter cell [116] is reduced, a magnitude of the voltage imbalance is suppressed.
In the present embodiment, by turning on the switch [700 (m, 2)], the output power of the converter unit [116] connected to the input port [115 (m)] is charged to the EV [124] where the connection to the output port [121 (2)] is maintained. That is, the transmission of the output power of the converter unit [116] connected to the input port [115 (m)] continues. Thus, the occurrence of the voltage imbalance of the DC bus [110, 11] associated with the disconnection of the EV [124] from the output port 121 (n) is suppressed.
Fig. 10 is a circuit diagram showing an example of a connection state of the input and output ports in the matrix-switch [120] in the case of discharging the storage battery mounted on the EV [124]. In the Figure, the transmission path of the power is indicated by an arrow.
Since the AC/DC converting circuit [109] and the DC/DC converting circuit [112] are both bidirectional power converting circuit, it is possible to charge and discharge the storage battery mounted on the EV [124].
As shown in FIG. 10, three EVs [124] are connected to the output ports 121(1), 121(2), 121(n).
The stored power of the EV [124] connected to the output port 121(1) is transmitted to the converter unit [116] connected to the input port 115(1) in a path, “bus [702(1)] → switch [700(1,1)] → bus [701(1)]”. Thus, the storage battery mounted on the EV [124] connected to the output port 121 (1) is discharged.
The stored power of the EV [124] connected to the output port 121(2) is transmitted to the converter unit [116] connected to the input port 115(2) in a path, “bus [702(2)] → switch [700(2,2)] → bus [701(2)]”. Thus, the storage battery mounted on the EV [124] connected to the output port 121 (2) is discharged.
The stored power of the EV [124] connected to the output port 121 (n) is transmitted to the converter unit [116] connected to the input port 115 (m) in a path, “bus [702 (n)] → switch [700 (m, n)] → bus [701 (m)]”. Thus, the storage battery mounted on the EV [124] connected to the output port 121 (n) is charged.
Fig. 11 is a circuit diagram showing a reconfiguration example of the connection state of the input and output ports in the matrix-switch [120] when discharging the storage battery mounted on the EV [124]. In the Figure, the transmission path of the power is indicated by an arrow.
Connection state in the matrix-switch transitions from the connection state shown in Fig. 10 to the connection state shown in Fig. 11.
In the connection state of Fig. 10, when there is a request for disconnection of the EV [124] connected to the output port 121 (n), the output current command value of the converter cell [108] is reduced as described above. Then, the connection state of the matrix-switch is reconfigured and transitions to the connection state of FIG. 10. Therefore, the magnitude of the voltage imbalance of the DC bus [110,111] can be suppressed.
As shown in FIG. 11, among the three EVs [124], the EV [124] connected to the output port [121 (n)] in FIG. 10 is disconnected from the output port 121 (n). At this time, the switch [700 (m, n)] is turned off.
With the switch [700(m, n)] turned off, the power transmission from the EV [124] connected to the output port [121(n)] is cut off. At this time, the voltage imbalance of the DC bus [110, 11] may occur, but since the output current of each converter cell [108] is reduced, a magnitude of the voltage imbalance is suppressed.
In the present embodiment, by turning on the switch [700 (m, 2)], the stored power of the EV [124] in which the connection to the output port [121 (2)] is maintained is discharged to the converter cell [108] connected to the input port [115 (m)]. That is, the transmission of power to the converter cell [108] connected to the input port [115(m)] continues. Thus, the occurrence of the voltage imbalance of the DC bus [110, 11] associated with the disconnection of the EV [124] from the output port 121 (n) is suppressed.
It is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention id capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.
For example, the storage device mounted on the EV may be a capacitor in addition to a storage battery.
For example, the semiconductor switching device constituting AC/DC converting circuit [109] and DC/DC converting circuit [112] is not limited to an IGBT, it may be a MOSFET or junction bipolar transistor.
For example, the semiconductor material constituting the semiconductor switching element and the diode is not limited to Si, it may be a wide gap semiconductor such as SiC or GaN.
Reference Signs List
100 AC power supply
102 Three-phase reactor
103,104 AC input terminal
108 Converter cell
109 AC/DC conversion circuit
110,111 DC Bus
112 DC/DC converter
113,114 DC output terminal
115 DC bus
120 Matrix-switch
121 Connection cable
122 EV charging port (charging stand)
124 EV
125 Charging cable
127 Charging device
128 Control unit
129 Voltage and current information
130 Drive signal
131 Voltage or current reference value
133 EV side information
310 High frequency transformer
300 DC/AC converting circuit
400 AC/DC converting circuit
Title of the Invention: Charging Device
Technical field
The present invention relates to a charging device for supplying charging power to a power storage device such as a storage battery.
Background Art
Recently, a charging device having a medium or high voltage isolated AC/DC converter is being applied with an increase in capacity of the charging device for an electric vehicle. Incidentally, hereinafter, "electric vehicle" will be described as "EV".
As a prior art relating to a charging device having a medium or high voltage isolated AC/DC converter, the technique described in Patent Document 1 is known.
In the technique described in Patent Document 1, AC inputs of a plurality of converter cells each comprising an isolated AC/DC converter are connected in series with each other. The AC inputs connected in series are directly connected to a high voltage AC power supply system without a transformer.
Each converter cell includes a AC/DC converting circuit having an AC input, a smoothing capacitor connected to the DC side of AC/DC converting circuit, an DC/AC converting circuit of which DC side is connected to the DC side of AC/DC converting circuit, a high-frequency transformer of which primary winding is connected to the AC side of DC/AC converting circuit and a AC/DC converting circuit of which AC side is connected to the secondary winding of the high-frequency transformer and that has a DC output.
The DC outputs of a plurality of converter cells are connected to a plurality of input ports of a switch unit. In the switch unit, between the plurality of input ports and the plurality of output ports, switches are connected in a matrix. Therefore, by operating the switch unit, the DC output of each converter cell is connected to an arbitrary output port. Each converter cell supplies DC power to a storage battery of an electric vehicle, which is a load connected to the output port, to charge the storage battery.
Citation List
Patent Literature
Patent Literature 1: WO2019/234988A1
Summary of Invention
Technical Problem
In the above prior art, when the connection state of the load in the plurality of output ports is changed, imbalance occurs in the DC voltage of the plurality of smoothing capacitors. When the imbalance occurs, the circuit may fail.
Therefore, the present invention provides a charging device capable of suppressing the voltage imbalance even if the connection state of the load varies.
Solution to problem
In order to solve the above problems, a charging device according to present invention, which charges a plurality of power storage devices, comprises a plurality of converter units for inputting AC power and outputting DC power, a matrix-switch having a plurality of input ports to which a plurality of outputs of the plurality of the converter units are connected and a plurality of output ports to which the plurality of the power storage devices are connected and a control unit controlling output current of the plurality of the converter units and a plurality of switches in the matrix-switch. Each of the plurality of the converter units has a converter cell including an AC/DC converting circuit for inputting the AC power and a DC/DC converting circuit, which is connected to the AC/DC converting circuit via a capacitor, outputting the DC power. A plurality of AC input terminals of the plurality of AC/DC converting circuit are connected in series with each other. The control unit reduces the output current of the plurality of converter units to a predetermined value when connecting the power storage device to the output port, or when disconnecting the power storage device from the output port, and thereafter, the control unit reconfigures a connection state between the plurality of the input ports and the plurality of the output ports in the matrix-switch.
Advantageous Effect of Invention
According to the present invention, it is possible to suppress the imbalance of the voltage.
Other problems, features and effects other than those described above will be clarified by the following description of the embodiment.
Brief Description of Drawings
Fig. 1 is a block diagram showing the configuration of a charging device for an electric vehicle as an embodiment of the present invention.
FIG. 2 is a circuit diagram illustrating an exemplary AC/DC converting circuit [109].
Fig. 3 is a circuit diagram showing another example of AC/DC converting circuit [109].
Fig. 4 is a circuit diagram illustrating an exemplary DC/DC converting circuit [112].
Fig. 5 is a block diagram showing a configuration of a control unit [128].
Fig. 6 is a flowchart showing the operation of the control unit [128].
Fig. 7 is a time chart showing the transitions of the operation mode (I, II, III) of the control unit [128].
Fig. 8 is a circuit diagram showing an example of a connection state of the input and output ports in the matrix-switch [120] in the case of charging the storage battery mounted on the EV [124].
Fig. 9 is a circuit diagram showing a reconfiguration example of the connection state of the input and output ports in the matrix-switch [120] in the case of charging the storage battery mounted on the EV [124].
Fig. 10 is a circuit diagram showing an example of a connection state of the input and output ports in the matrix-switch [120] in the case of discharging the storage battery mounted on the EV [124].
Fig. 11 is a circuit diagram showing a reconfiguration example of the connection state of the input and output ports in the matrix-switch [120] when discharging the storage battery mounted on the EV [124].
Description of Embodiment
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In each Figure, the same reference numerals denote components having the same or similar functions.
Fig. 1 is a block diagram showing the configuration of a charging device for an electric vehicle as an embodiment of the present invention.
A charging device [127] includes a three-phase four-wire AC power source [100], a plurality (m) of converter units [116] for inputting three-phase AC power through a three-phase reactor [102]. “m” is an integer not smaller than 2. Each converter unit [116] has three converter cells [108] for three phases to input single-phase AC power from one phase of AC power supply [100]. Each converter cell [108] includes an AC/DC converting circuit [109] for converting a single phase AC power into DC power and a DC/DC converting circuit [112] for converting the DC power output by AC/DC converting circuit [109] into DC power having different voltage. DC output terminals of the AC/DC converting circuit [109] are connected to the DC input terminals of the DC/DC converting circuit [112] by a DC bus [110, 111].
In a plurality (m) of the converter units [116], AC inputs for one phase among the three converter cells [108] for the three phases provided in each converter unit [116] are connected in series with each other. That is, AC input terminals [103,104] of each of the plurality (m) of the AC/DC converting circuits [109] are connected in series with each other. One end and the other end [106] of the series connection of the AC input terminals are respectively connected to one phase of the AC power supply [100] (e.g., U-phase) and the neutral point N of the AC power supply [100]. This allows the input of the converter cell [108] to be directly connected to a high voltage (e.g., 6.6kV or 11kV) AC power source [100] without a transformer.
The DC outputs of three converter cells [108] for three phases provided in each converter unit [116] are connected in parallel to each other. That is, the DC-output terminals [113,114] of the three DC/DC converting circuits [112] for the three-phases are connected in parallel. Thus, the DC output of each converter unit [116] is configured.
A matrix-switch [120] has a plurality (m) of input ports and a plurality (n) of output ports. “n” is an integer not smaller than 2. The matrix-switch [120] has m × n switches arranged in a matrix of m rows and n columns between a plurality (m) of input ports and a plurality (n) of output ports. Each DC output of a plurality (m) of the converter units [116] is connected to a different input port among a plurality (m) of input ports via a DC bus [115]. By operating these switches, each input port and an arbitrary output port is electrically connected.
Incidentally, as the switch in the matrix-switch [120], electromagnetic or electronic switches are applied.
Each of the plurality (n) of the output ports of the matrix-switch [120] is electrically connected to an EV charging port [122] (charging stand) through a connection cable [121]. Each of the plurality (n) of the EV charging ports [122] (charging stands) is connected to an EV [124] through a charging cable [125].
When the matrix-switch [120] is operated and any DC output of the plurality (m) of the converter units [116] is connected, the DC power output by the converter unit [116] is charged in the storage battery mounted on the EV [124]. By controlling the plurality of switches in the matrix-switch [120], the DC output of the converter unit [116] is connected to the EV [124] or disconnected from the EV [124]. Further, in the case of such high-speed charging, DC outputs of a plurality (e.g., two) of the converter units [116] can be connected to a single EV with opening and closing control of the matrix-switch [120].
A control unit [128] generates a drive signal [130] to the matrix-switch [120] and each converter cell [108] for opening and closing control of the matrix-switch [120] and DC output power control of each converter cell [108] based on voltage and current information [129] in the charging device [127], a voltage or current reference value [131], and EV-side information [133] from a charging port group [132] including a plurality of the EV charging ports [122] (charging stands).
In the present embodiment, the voltage and current information [129] includes a voltage [117] of a DC bus [110, 111] that connects AC/DC converting circuit [109] and DC/DC converting circuit [112] in each converter cell [108], and a voltage and current [118] in the DC output [115] of each converter unit [116]. Voltage and current information [129] are detected by voltage and current sensors, respectively.
Further, in the present embodiment, the EV-side information [133] includes SOC information [123] relating to the state of charge (SOC) of the storage battery of the EV, user setting information such as the charging speed (low speed, medium speed, high speed), and EV connection information relating to the connection and disconnection of the EV [124] to the EV charging port [122] (charging stand). The SOC information [123] is transmitted to the control unit [128] via a communication line provided in the charging cable [125] and via the EV charging port [122] (charging stand). User setting information is set with switch operation or button operation of the EV charging port [122] (charging stand)]. The EV connection information is detected by the EV charging port [122] (charging stand). User setting information and EV connection information are transmitted to the control unit [128] by the EV charging port [122] (charging stand).
FIG. 2 is a circuit diagram illustrating an exemplary AC/DC converting circuit [109].
As shown in FIG. 2, AC/DC converting circuit [109] includes a single-phase full-bridge circuit using a semiconductor device [200] which includes a semiconductor switching element (in FIG. 2, IGBT) and a diode connected each other in anti-parallel and a DC link capacitor [201] connected in parallel to the single-phase full-bridge circuit. The series connection point of the two semiconductor devices [200] in each half-bridge circuit is defined as the AC input [103,104]. The parallel connection points of the two half-bridge circuits and the DC link capacitor [201] are connected as DC outputs to the DC bus [110,111].
AC power input to the AC input terminal [103,104] is rectified by the diode and converted into DC power. The DC power is output to the DC bus [110,111] while charging the DC link capacitor [201].
The AC/DC converting circuit [109] can convert the DC power input to the DC bus [110,111] into AC power and output from the AC input [103,104] by the semiconductor switching element. That is, AC/DC converting circuit [109] can operate as a bidirectional power converting circuit.
Fig. 3 is a circuit diagram showing another example of AC/DC converting circuit [109].
As shown in Fig. 3, AC/DC converting circuit [109] has a parallel connection of a half-bridge circuit using the semiconductor device [200] which includes the semiconductor switching element (in Fig. 3, IGBT) and the diode connected each other in anti-parallel and a series connection circuit of DC link capacitors [201, 202].
The series connection points of the two semiconductor devices [200] in the half-bridge circuit and the series connection points of the two DC link capacitors [201, 202] are the AC input [103] and the AC input[104] respectively. Both ends of the half-bridge circuit, i.e., both ends of the series-connected circuit of the DC link capacitor [201,202], are connected DC to the DC bus [201,202].
The AC power input to the AC input [103,104] is rectified by a diode and is converted into DC power. The DC power alternately charges the DC link capacitor [201,202] according to the polarity of the AC input voltage.
The AC/DC converting circuit [109] shown in FIG. 3 can output from the AC input terminal [103,104] by converting the DC power input to the DC output terminal [110,111] to AC power with using the semiconductor switching element. That is, AC/DC converting circuit [109] can operate as a bidirectional power converting circuit.
Fig. 4 is a circuit diagram illustrating an exemplary DC/DC converting circuit [112].
As shown in Fig. 4 DC/DC converting circuit [112] is an isolated type and includes a DC/AC converting circuit [300] and an AC/DC converting circuit [400] connected to DC/AC converting circuit [300] via a high-frequency transformer [310].
DC/AC converting circuit [300] includes a single-phase full-bridge circuit using a semiconductor device [301] which includes a semiconductor switching element (in FIG. 4, IGBT) and a diode connected each other in anti-parallel and a primary capacitor [311] connected in parallel to the single-phase full-bridge circuit.
The parallel connection points of the two half-bridge circuits and the primary capacitor [311] are connected as DC inputs to the DC bus [110,111].
Series connection point of the two semiconductor devices [301] in each half-bridge circuit, as an AC output, is connected to the primary winding [305] of the high-frequency transformer [310] via a reactor [303].
AC/DC converting circuit [400] includes a single-phase full-bridge circuit using a semiconductor device [312] which includes a semiconductor switching element (in FIG. 4, IGBT) and a diode connected each other in anti-parallel and a secondary capacitor [313] connected in parallel to the single-phase full-bridge circuit.
The series connection point of the two semiconductor devices [312] in each half-bridge circuit, as an AC input, is connected to the secondary winding [308] of the high-frequency transformer [310]. The parallel connection points of the two half-bridge circuits as well as the secondary capacitor [313] are connected to DC bus [113,114] as DC outputs.
DC/AC converting circuit [300] converts the DC power input from the DC bus [110,111] into AC power by the semiconductor switching element, and outputs the DC power to the primary winding [305] of the high-frequency transformer [310]. The high-frequency transformer [310] step-down or step-up the AC voltage to output the AC power received by the primary winding [305] to the secondary winding [308].
AC power input to the AC input terminal [103,104] is rectified by a diode and converted into DC power. The DC power is output to the DC bus [110,111] while charging the DC link capacitor [201].
The AC/DC converting circuit [400] rectifies the AC power input from the secondary winding [308] by a diode and converts it into DC power. The DC power is output to the DC bus [110,111] while charging the secondary capacitor [313].
The AC/DC converting circuit [400] can convert the DC power input from the DC bus [113,114] into AC power by the semiconductor switching element. The DC/AC converting circuit [300] can convert AC power input from AC/DC converting circuit [400] via the high-frequency transformer [310] into DC power by a diode. Consequently, the AC/DC converting circuit [400] and DC/AC converting circuit [300] can operate as bidirectional power converting circuits.
Fig. 5 is a block diagram showing a configuration of a control unit [128].
As shown in Fig. 5, the control unit [128] has a first control unit [401] and a second control unit [402].
The first control unit [401] generates an output current command [400] of the converter cell [108] and a matrix-switch control command [403] for setting the switching states (ON and OFF) of the switches in the matrix-switch [120] based on the voltage or current reference value [131] and the EV-side information [133] (SOC, user setting information).
The second control unit [402] generates a drive signal [130] for the converter cell [108] and the matrix-switch [120] based on the output current command [400] generated by the first control unit [401] and the voltage and current information [129] in the charging device [127].
For example, the drive signal [130] is an on/off drive signal to the switches in the matrix-switch [120] and a gate drive signal to the semiconductor switching element in the converter cell [108].
Fig. 6 is a flowchart showing the operation of the control unit [128]. The control unit [128] includes a computer system such as a microcomputer, and performs a control operation when the computer system executes a predetermined program.
In step S0, the control unit [128] starts the control operation.
Next, in step S1, the control unit [128] checks the connection state of the EV [124] in the plurality (n) of the EV charging ports [122] (charging stands) based on the EV-side information [133].
Next, in step S2, the control unit [128] checks or calculates the charging power required by the EV [124] connected to the EV charging port [122] (charging stand) based on the EV-side information [133].
Next, in step S3, the control unit [128] sets a connection configuration between a plurality (m) of input ports (converter unit [116] side) and a plurality (n) of output ports (EV charging port [122] side) in the matrix-switch [120] based on the EV-side information [133]. That is, the control unit [128] generates a matrix-switch control command [403] with using the first control unit [401] (FIG. 2).
Next, in step S4, the control unit [128] calculates the range of the charging current for each EV [124], i.e., the maximum value (Iref_max), the minimum value (Iref_min), and the average value (Iref_avg(=(Iref_max+Iref_min)/2)) based on the allowable maximum voltage and the allowable peak-to-peak value of ripple, i.e., the allowable voltage variation range in the high voltage (HV) side capacitor, i.e., the DC link capacitor [201] (FIG. 2) or the primary side capacitor [311] (FIG. 4) connected to the DC bus [110, 111] and based on the output power required for each converter cell [108] according to the result of the execution of step S2.
Next, in step S6, the control unit [128] determines whether the charging current user set value (Iref_user) corresponding to the user setting information (such as the charging speed) is within the range of the charging current calculated in step S4 (Iref_min ≦ Iref_user ≦ Iref_max). Additionally, the control unit [128] extracts the charging current user set value (Iref_user) corresponding to the user setting information (such as the charging speed) from the relationship between the user setting information and the charging current user set value stored in advance (Step S5).
When the control unit [128] determines that the charging current user set value (Iref_user) is within the range of the charging current calculated in Step S4 (Yes in Step S6) (Iref_min ≦ Iref_user ≦ Iref_max), then the control unit [128] executes Step S7. When the control unit [128] determines that the charging current user set value (Iref_user) is not within the range of the charging current calculated in step S4 (Iref_min ≦ Iref_user ≦ Iref_max) (No in step S6) (Iref_min > Iref_user, Iref_user > Iref_max), then the control unit [128] executes step S8.
In step S7, the control unit [128] sets the value of the charging current to the charging current user set value (Iref_user).
In step S8, the control unit [128] sets the value of the charging current to the average value (Iref_avg (= (Iref_max + Iref_min))/2).
Next, in step S9, the control unit [128] sets the charging current command value to the converter cell [108] in accordance with steps S7 and S8. That is, the control unit [128] generates an output current command [400] (FIG. 2) with using the first control unit [401] (FIG. 2).
Next, in step S10, the control unit [128] determines whether or not there is a request relating to the EV disconnection, or the end of charging, or an additional connection of another EV, based on the EV-side information [133].
When the control unit [128] determines that there is a request (Yes in step S10), then the control unit [128] executes step S11. Further, when the control unit [128] determines that there is no request (No in Step S10), then the control unit [128] executes the steps S4 and subsequent steps again.
In step S11, the control unit [128] changes the output current command [400] so that the output current of each of the plurality (m) of converter units [116] used by the charging device [127] is reduced. At this time, the control unit [128] controls the plurality (three) of the converter cells [108] for three phases connected each other in parallel in each converter unit [116] so that the output current of each converter cell [108] is reduced.
According to the studies of the present inventors, it is preferable that the output current command after the change is set so that the imbalance of the voltage of the DC bus [110,111] to which the capacitor (201 and 202 in Fig. 2 and Fig. 3, 311 in Fig. 4) is connected is less than 30% of the reference value of the DC bus voltage (e.g., (AC power supply voltage)/m). For example, the high voltage capacitor (201 and 202 in Fig. 2 and Fig. 3, 311 in Fig. 4) voltage ripple is kept under 30% of the reference command value. The output current command after the change may be a predetermined value close to zero or zero.
Next, in step S12, the control unit [128] reconfigures a connection configuration between the plurality (m) of input ports and the plurality (n) of output ports in the matrix-switch [120] with the new connection and disconnection of the EV [124].
Next, in step S13, the control unit [128] executes step S1 and subsequent steps again after a predetermined delay time. The delay time is set to the time (e.g., 1 μsec or more) required to stop the transient fluctuation of the voltage and current in the converter unit [116] and the converter cell [108] associated with the new connection or disconnection of the EV.
Mode I, II, III in Fig. 6 will be described later.
Fig. 7 is a time chart showing the transitions of the operation mode (I, II, III) of the control unit [128].
Mode I corresponds to the operation of steps S0 to S9 in the flowchart of Fig. 6. That is, the mode I is a charging current command value setting operation to each converter cell [108] immediately after the start of operation.
Mode II corresponds to the operation of steps S10 to S13 in the flowchart of Fig. 6. That is, in the operation mode II, when changing the connection state of the EV, the output current command value of each converter cell [108] is set to the minimum level, and then the connection state of the input and output ports in the matrix-switch [200] is reconfigured.
Mode III corresponds to the operation of steps S1 to S19 in the flowchart of Fig. 6. That is, the operation mode I is the charging current command value setting operation to each converter cell [108] after the start of the operation.
As shown in Fig. 7, the control unit [128] operates first in the operation mode I at the operation start point (t0). When there is a request regarding the change of the connection state of the EV (t1), the operation mode changes to mode II.
In mode II, as shown in Fig. 6 (step S13), a predetermined delay time is set. Therefore, the time width of mode II becomes a constant value including the delay time.
When mode II ends (t2), the operation mode transitions to mode III. Hereafter (t3 onward), the operation mode repeats mode II and mode III alternately.
During period to-t1, EVs connected to the EV charging ports 1-m starts to charge and the battery voltage increases. As t1 instant (start of mode II), the EV charging port 1 receives a command from the control unit [128] to stop EV charging at the EV charging port 1. Hence, the control unit [128] sends reference current commands to all converter units [116] to make it to zero for safe EV disconnection. From t1-t2 time duration all converter currents reduce to zero. After current goes down to zero, the EV is disconnected from the EV charging port 1, however all other ports are still connected. So, the EV voltage will reflect at the connection ports for the time duration t2-t3. During this time interval, the converter unit [116] connected to the EV charging port 1 will be reconnected with one of the other available ports where the EV is still connected by the matrix-switch [120]. From t3-t4 time duration, the EV charging port m and other ports will again start the EV charging process. The voltage and current waveforms are shown for the EV charging ports [122].
Next, an example of reconfiguration of the connection state of the input and output ports in the matrix-switch [120] is described.
Fig. 8 is a circuit diagram showing an example of a connection state of the input and output ports in the matrix-switch [120] in the case of charging the storage battery mounted on the EV [124]. In the Figure, the transmission path of the power is indicated by an arrow. The configuration of the matrix-switch [120] in Fig. 8 described below is the same as that of the matrix-switch [120] described in Figs. 9 to 11.
The matrix-switch [120] has a plurality (m × n) of switches [700 (1, 1)-700 (m, n)] arranged in a matrix of m rows and n columns. The matrix-switch [120] has a plurality (m) of input ports [115(1)-115(m)] to which a plurality (m) of DC outputs [115] of a plurality (m) of the converter units [116] are electrically connected. Further, the matrix-switch [120] has a plurality (n) of output ports [121 (1)-121 (n)] which are electrically connected to a plurality (n) of connecting cables [121].
In the matrix-switch [120], input ports [115(1)-115(m)] are connected to buses [701(1)-701(m)], respectively, and output ports [121(1)-121(n)] are connected to buses [702(1)-702(n)]. The switch [700(m, n)] is connected between the bus [701(m)] and the bus [702(n)].
As shown in Fig. 8, n EVs [124] are connected to the output ports 121(1), 121(2), 121(n).
The output power of the converter unit [116] connected to the input port 115 (1) is transmitted to the EV [124] connected to the output port 121 (1) in a path, “bus [701 (1)] → switch [700 (1, 1)] → bus [702 (1)]. Thus, the storage battery mounted on the EV [124] connected to the output port 121 (1)” is charged.
The output power of the converter unit [116] connected to the input port 115 (2) is transmitted to the EV [124] connected to the output port 121 (2) in a path, “bus [701 (2)] → switch [700 (2, 2)] → bus [702 (2)]”. Thus, the storage battery mounted on the EV [124] connected to the output port 121 (2) is charged.
The output power of the converter unit [116] connected to the input port 115 (m) is transmitted to the EV [124] connected to the output port 121 (n) in a path, “bus [701 (m)] → switch [700 (m, n)] → bus [702 (n)]”. Thus, the storage battery mounted on the EV [124] connected to the output port 121 (n) is charged.
Fig. 9 is a circuit diagram showing a reconfiguration example of the connection state of the input and output ports in the matrix-switch [120] in the case of charging the storage battery mounted on the EV [124]. In the Figure, the transmission path of the power is indicated by an arrow.
Connection state in the matrix-switch transitions from the connection state shown in Fig.8 to the connection state shown in Fig.9.
In the connection state of Fig. 8, when there is a request for disconnection of the EV [124] connected to the output port 121 (n), the output current command value of the converter cell [108] is reduced as described above. Then, the connection state of the matrix-switch is reconfigured and transitions to the connection state of Fig.9.
Therefore, the magnitude of the voltage imbalance of the DC bus [110,111] can be suppressed.
As shown in Fig. 9, among the three EVs [124], the EV [124] connected to the output port [121 (n)] in FIG. 8 is disconnected from the output port 121 (n). At this time, the switch [700 (m, n)] is turned off.
With the switch [700(m, n)] off, the power transmission to the EV [124] connected to the output port [121(n)] is interrupted. At this time, the voltage imbalance of the DC bus [110, 11] may occur, but since the output current of each converter cell [116] is reduced, a magnitude of the voltage imbalance is suppressed.
In the present embodiment, by turning on the switch [700 (m, 2)], the output power of the converter unit [116] connected to the input port [115 (m)] is charged to the EV [124] where the connection to the output port [121 (2)] is maintained. That is, the transmission of the output power of the converter unit [116] connected to the input port [115 (m)] continues. Thus, the occurrence of the voltage imbalance of the DC bus [110, 11] associated with the disconnection of the EV [124] from the output port 121 (n) is suppressed.
Fig. 10 is a circuit diagram showing an example of a connection state of the input and output ports in the matrix-switch [120] in the case of discharging the storage battery mounted on the EV [124]. In the Figure, the transmission path of the power is indicated by an arrow.
Since the AC/DC converting circuit [109] and the DC/DC converting circuit [112] are both bidirectional power converting circuit, it is possible to charge and discharge the storage battery mounted on the EV [124].
As shown in FIG. 10, three EVs [124] are connected to the output ports 121(1), 121(2), 121(n).
The stored power of the EV [124] connected to the output port 121(1) is transmitted to the converter unit [116] connected to the input port 115(1) in a path, “bus [702(1)] → switch [700(1,1)] → bus [701(1)]”. Thus, the storage battery mounted on the EV [124] connected to the output port 121 (1) is discharged.
The stored power of the EV [124] connected to the output port 121(2) is transmitted to the converter unit [116] connected to the input port 115(2) in a path, “bus [702(2)] → switch [700(2,2)] → bus [701(2)]”. Thus, the storage battery mounted on the EV [124] connected to the output port 121 (2) is discharged.
The stored power of the EV [124] connected to the output port 121 (n) is transmitted to the converter unit [116] connected to the input port 115 (m) in a path, “bus [702 (n)] → switch [700 (m, n)] → bus [701 (m)]”. Thus, the storage battery mounted on the EV [124] connected to the output port 121 (n) is charged.
Fig. 11 is a circuit diagram showing a reconfiguration example of the connection state of the input and output ports in the matrix-switch [120] when discharging the storage battery mounted on the EV [124]. In the Figure, the transmission path of the power is indicated by an arrow.
Connection state in the matrix-switch transitions from the connection state shown in Fig. 10 to the connection state shown in Fig. 11.
In the connection state of Fig. 10, when there is a request for disconnection of the EV [124] connected to the output port 121 (n), the output current command value of the converter cell [108] is reduced as described above. Then, the connection state of the matrix-switch is reconfigured and transitions to the connection state of FIG. 10. Therefore, the magnitude of the voltage imbalance of the DC bus [110,111] can be suppressed.
As shown in FIG. 11, among the three EVs [124], the EV [124] connected to the output port [121 (n)] in FIG. 10 is disconnected from the output port 121 (n). At this time, the switch [700 (m, n)] is turned off.
With the switch [700(m, n)] turned off, the power transmission from the EV [124] connected to the output port [121(n)] is cut off. At this time, the voltage imbalance of the DC bus [110, 11] may occur, but since the output current of each converter cell [108] is reduced, a magnitude of the voltage imbalance is suppressed.
In the present embodiment, by turning on the switch [700 (m, 2)], the stored power of the EV [124] in which the connection to the output port [121 (2)] is maintained is discharged to the converter cell [108] connected to the input port [115 (m)]. That is, the transmission of power to the converter cell [108] connected to the input port [115(m)] continues. Thus, the occurrence of the voltage imbalance of the DC bus [110, 11] associated with the disconnection of the EV [124] from the output port 121 (n) is suppressed.
It is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention id capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.
For example, the storage device mounted on the EV may be a capacitor in addition to a storage battery.
For example, the semiconductor switching device constituting AC/DC converting circuit [109] and DC/DC converting circuit [112] is not limited to an IGBT, it may be a MOSFET or junction bipolar transistor.
For example, the semiconductor material constituting the semiconductor switching element and the diode is not limited to Si, it may be a wide gap semiconductor such as SiC or GaN.
Reference Signs List
100 AC power supply
102 Three-phase reactor
103,104 AC input terminal
108 Converter cell
109 AC/DC conversion circuit
110,111 DC Bus
112 DC/DC converter
113,114 DC output terminal
115 DC bus
120 Matrix-switch
121 Connection cable
122 EV charging port (charging stand)
124 EV
125 Charging cable
127 Charging device
128 Control unit
129 Voltage and current information
130 Drive signal
131 Voltage or current reference value
133 EV side information
310 High frequency transformer
300 DC/AC converting circuit
400 AC/DC converting circuit
Claims
Claim 1
A charging device for charging a plurality of power storage devices comprising:
a plurality of converter units for inputting AC power and outputting DC power;
a matrix-switch having a plurality of input ports to which a plurality of outputs of the plurality of the converter units are connected and a plurality of output ports to which the plurality of the power storage devices are connected;
a control unit controlling output current of the plurality of the converter units and a plurality of switches in the matrix-switch,
wherein each of the plurality of the converter units has a converter cell including an AC/DC converting circuit for inputting the AC power and a DC/DC converting circuit, which is connected to the AC/DC converting circuit via a capacitor, outputting the DC power,
wherein a plurality of AC input terminals of the plurality of AC/DC converting circuit are connected in series with each other, and
wherein the control unit reduces the output current of the plurality of converter units to a predetermined value when connecting the power storage device to the output port, or when disconnecting the power storage device from the output port, and thereafter, the control unit reconfigures a connection state between the plurality of the input ports and the plurality of the output ports in the matrix-switch.
Claim 2
A charging device according to claim 1,
wherein the control unit sets output current commands of the plurality of the converter units after reconfiguring the connection state between the plurality of input ports and the plurality of output ports in the matrix-switch.
Claim 3
A charging device according to claim 1,
wherein a high voltage capacitor voltage ripple is kept under 30% of a reference command value.
Claim 4
A charging device according to claim 1,
wherein the predetermined value of the output current is can be reduced to zero.
Claim 5
A charging device according to claim 1,
wherein the control unit sets output current commands of the plurality of the converter units after a predetermined delay time from reconfiguring the connection state between the plurality of input ports and the plurality of output ports in the matrix-switch.
Claim 6
A charging device according to claim 5,
wherein the predetermined delay time is at least 1μsec.
Claim 7
A charging device according to claim 1,
wherein each of the plurality of converter units has a plurality of the converter cells of which DC outputs are connected each other in parallel.
Claim 8
A charging device according to claim 1,
wherein charging speed of the power storage device can be set.
Claim 9
A charging device according to claim 1,
wherein the AC/DC converting circuit and the DC/DC converting circuit are bidirectional power converting circuits.
Claim 1
A charging device for charging a plurality of power storage devices comprising:
a plurality of converter units for inputting AC power and outputting DC power;
a matrix-switch having a plurality of input ports to which a plurality of outputs of the plurality of the converter units are connected and a plurality of output ports to which the plurality of the power storage devices are connected;
a control unit controlling output current of the plurality of the converter units and a plurality of switches in the matrix-switch,
wherein each of the plurality of the converter units has a converter cell including an AC/DC converting circuit for inputting the AC power and a DC/DC converting circuit, which is connected to the AC/DC converting circuit via a capacitor, outputting the DC power,
wherein a plurality of AC input terminals of the plurality of AC/DC converting circuit are connected in series with each other, and
wherein the control unit reduces the output current of the plurality of converter units to a predetermined value when connecting the power storage device to the output port, or when disconnecting the power storage device from the output port, and thereafter, the control unit reconfigures a connection state between the plurality of the input ports and the plurality of the output ports in the matrix-switch.
Claim 2
A charging device according to claim 1,
wherein the control unit sets output current commands of the plurality of the converter units after reconfiguring the connection state between the plurality of input ports and the plurality of output ports in the matrix-switch.
Claim 3
A charging device according to claim 1,
wherein a high voltage capacitor voltage ripple is kept under 30% of a reference command value.
Claim 4
A charging device according to claim 1,
wherein the predetermined value of the output current is can be reduced to zero.
Claim 5
A charging device according to claim 1,
wherein the control unit sets output current commands of the plurality of the converter units after a predetermined delay time from reconfiguring the connection state between the plurality of input ports and the plurality of output ports in the matrix-switch.
Claim 6
A charging device according to claim 5,
wherein the predetermined delay time is at least 1μsec.
Claim 7
A charging device according to claim 1,
wherein each of the plurality of converter units has a plurality of the converter cells of which DC outputs are connected each other in parallel.
Claim 8
A charging device according to claim 1,
wherein charging speed of the power storage device can be set.
Claim 9
A charging device according to claim 1,
wherein the AC/DC converting circuit and the DC/DC converting circuit are bidirectional power converting circuits.
Abstract
A charging device capable of suppressing the voltage imbalance is disclosed. The charging device [127] has a plurality of converter units [116], a matrix-switch [120] having a plurality of input ports connected to the plurality of the converter units and a plurality of output ports connected to the power storage devices and a control unit [128] controlling output current of the converter units and the matrix-switch. The converter unit has a converter cell including an AC/DC converting circuit and a DC/DC converting circuit connected to the AC/DC converting circuit via a capacitor. A plurality of AC input terminals of the plurality of AC/DC converting circuits are connected in series. The control unit reduces the output current of the plurality of converter units to a predetermined value and thereafter, the control unit reconfigures a connection state between the input ports and the output ports in the matrix-switch.
Representing Drawing: Fig. 1
A charging device capable of suppressing the voltage imbalance is disclosed. The charging device [127] has a plurality of converter units [116], a matrix-switch [120] having a plurality of input ports connected to the plurality of the converter units and a plurality of output ports connected to the power storage devices and a control unit [128] controlling output current of the converter units and the matrix-switch. The converter unit has a converter cell including an AC/DC converting circuit and a DC/DC converting circuit connected to the AC/DC converting circuit via a capacitor. A plurality of AC input terminals of the plurality of AC/DC converting circuits are connected in series. The control unit reduces the output current of the plurality of converter units to a predetermined value and thereafter, the control unit reconfigures a connection state between the input ports and the output ports in the matrix-switch.
Representing Drawing: Fig. 1
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