JP2004159405A

JP2004159405A - Uninterruptible power system

Info

Publication number: JP2004159405A
Application number: JP2002321363A
Authority: JP
Inventors: Kazuaki Kurita; 和哲栗田; Takuya Adachi; 卓也足立
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 2002-11-05
Filing date: 2002-11-05
Publication date: 2004-06-03

Abstract

【課題】無停電電源装置において、バックアップの長時間化、メンテナンスの工数低減化などが可能な技術の提供。
【解決手段】エネルギー蓄積手段として二次電池と電気二重層コンデンサとを用い、それぞれにダイオードなどの逆流防止用素子を直列接続した回路を互いに並列接続し、交流電源の電力低下時において、該電気二重層コンデンサの放電電圧が該二次電池の放電電圧よりも高い間は、該電気二重層コンデンサ側の逆流防止用素子をオン状態にして該電気二重層コンデンサの電力を負荷側に供給し、該電気二重層コンデンサの放電電圧が下がり該二次電池の放電電圧よりも低くなったときは、該二次電池側の逆流防止用素子をオン状態にして該二次電池の電力を負荷側に供給する構成とする。
【選択図】図１An uninterruptible power supply device is provided with a technology capable of, for example, extending backup time and reducing maintenance man-hours.
A rechargeable battery and an electric double layer capacitor are used as energy storage means, and circuits in which respective backflow prevention elements such as diodes are connected in series are connected in parallel to each other. While the discharge voltage of the double-layer capacitor is higher than the discharge voltage of the secondary battery, the backflow prevention element on the electric double-layer capacitor side is turned on to supply the electric double-layer capacitor power to the load side, When the discharge voltage of the electric double layer capacitor decreases and becomes lower than the discharge voltage of the secondary battery, the backflow prevention element on the secondary battery side is turned on to transfer the power of the secondary battery to the load side. It is configured to supply.
[Selection diagram] Fig. 1

Description

【０００１】
【発明の属する技術分野】
本発明は、交流電源の電力低下時に、二次電池などのエネルギー蓄積手段から電力を、負荷としてのコンピュータ関連装置やその応用製品などの電子機器に供給する無停電電源装置に関する。
【０００２】
【従来の技術】
交流電源の電力低下時にエネルギー蓄積手段からの電力を負荷側に供給する技術としては、例えば、特開２０００−１８４７５２公報（特許文献１）、特開平９−３０８１３５公報（特許文献２）、及び特開２０００−１３９０４１号公報（特許文献３）に記載されたものがある。特開２０００−１８４７５２公報には、変圧器や蓄電池などの構造や形状を変えずに、小形で安価な無停電電源装置を提供するために、装置ケーシング内において蓄電池の上部に、インバータ構成用のスイッチング素子を搭載した基板を配し、さらに該基板の上部に変圧器を配する構成が記載されている。特開平９−３０８１３５公報には、装置の大型化を抑え、停電時の出力保持時間が長く、充電時間の短いエネルギー蓄積手段を提供するために、交流電源の電圧低下時に、電気二重層コンデンサを、電界コンデンサやバッテリーに替えて用いる構成が記載されている。また、特開２０００−１３９０４１号公報には、船内負荷に供給する定常電流の無停電電源電流及びディーゼルエンジン始動用のモータ（符号６）に供給する瞬時大電流を、１つの装置から供給可能な船舶用電源装置を提供するために、二次電池（符号２）と電気二重層コンデンサ（符号１）とを並列接続し、二次電池と船内負荷との間に、二次電池から負荷（符号１１）に流れる電流方向を順方向とする整流器（符号３）と、抵抗器（符号４）との並列回路を接続する構成が記載されている。抵抗器には過電流遮断器（符号５）を直列に接続する。
【０００３】
【特許文献１】
特開２０００−１８４７５２公報
【特許文献２】
特開平９−３０８１３５公報
【特許文献３】
特開２０００−１３９０４１号公報
【０００４】
【発明が解決しようとする課題】
上記従来技術のうち、特開２０００−１８４７５２公報記載の技術は、エネルギー蓄積手段として蓄電池を用いた構成であり、これだけでは一般に、寿命が短く、放電後の充電にも長い時間が必要である。特開平９−３０８１３５公報記載の技術は、エネルギー蓄積手段として電気二重層コンデンサを用いた構成であり、一般には停電時における出力保持時間が短い。このため、長時間のバックアップ用としては、電気二重層コンデンサの大容量化が必要となり、装置の大型化を伴うおそれがある。また、特開２０００−１３９０４１号公報記載の技術は、エネルギー蓄積手段として二次電池と電気二重層コンデンサを単に並列接続し、該並列接続点の後段側に整流器３と抵抗器４の並列回路を設けた構成である。このため、二次電池２と電気二重層コンデンサ１の電圧及び内部抵抗値の差によって、二次電池２から電気二重層コンデンサ１へ充電電流が流れ、二次電池２の放電が行われる。これによって、回路上に急激な充電電流が流れ、回路の定格電流を越えたりして、回路の破壊や異常発熱の原因となるおそれもある。
本発明の課題点は、上記従来技術の状況に鑑み、無停電電源装置において、（１）二次電池の寿命を延ばせること、（２）装置を大型化させない構成にできること、（３）短い充電時間で対応可能なこと、（４）メンテナンスの工数を低減できるようにすること、（５）複数のエネルギー蓄積手段を用いた場合も、該エネルギー蓄積手段間で充電電流が流れないようにできること、（６）回路の破壊や異常発熱が起きない構成であること、等である。
本発明の目的は、かかる課題点を解決できる技術の提供にある。
【０００５】
【課題を解決するための手段】
上記課題点を解決するために、本発明では、基本的に、無停電電源装置において、エネルギー蓄積手段として二次電池と電気二重層コンデンサとを用い、それぞれにダイオードなどの逆流防止用素子を直列接続した回路を相互に並列接続し、交流電源の電力低下時において、該電気二重層コンデンサの放電電圧が該二次電池の放電電圧よりも高い間は、該電気二重層コンデンサ側の逆流防止用素子をオン状態にして該電気二重層コンデンサの電力を負荷側に供給し、該電気二重層コンデンサの放電電圧が下がり該二次電池の放電電圧よりも低くなったときは、該二次電池側の逆流防止用素子をオン状態にして該二次電池の電力を負荷側に供給する構成とする。具体的には、無停電電源装置として、（１）エネルギー蓄積手段として電気二重層コンデンサと二次電池とを有し、該電気二重層コンデンサに第１の逆流防止用素子が直列接続された第１の電力供給系と、該二次電池に第２の逆流防止用素子が直列接続された第２の電力供給系とを並列に備え、上記電気二重層コンデンサ、上記二次電池の放電電圧の差に基づき、上記第１の逆流防止用素子のオン状態から上記第２の逆流防止用素子のオン状態へと切替えることで、負荷側への電力供給を、上記第１の電力供給系による供給から上記第２の電力供給系による供給へと切替えられる構成とする。（２）第１のエネルギー蓄積手段としての電気二重層コンデンサに第１の逆流防止用素子が直列接続された第１の電力供給系と、第２のエネルギー蓄積手段としての二次電池に第２の逆流防止用素子が直列接続された第２の電力供給系とを並列に備え、上記電気二重層コンデンサの放電電圧が上記二次電池の放電電圧よりも高いときは、上記第１の逆流防止用素子をオン状態にして上記第１の電力供給系から上記電気二重層コンデンサの電力を負荷側に供給し、該電気二重層コンデンサの放電電圧が下がって該二次電池の放電電圧よりも低くなったときは、上記第２の逆流防止用素子をオン状態にして上記第２の電力供給系から上記二次電池の電力を負荷側に供給可能とした構成とする。（３）第１のエネルギー蓄積手段としての電気二重層コンデンサと、第２のエネルギー蓄積手段としての二次電池と、上記電気二重層コンデンサに直列接続された第１の逆流防止用素子と、上記二次電池に直列接続された第２の逆流防止用素子とが互いに並列接続された構成を有し、該電気二重層コンデンサの放電電圧が該二次電池の放電電圧よりも高いときは、該第１の逆流防止用素子をオン状態にして該電気二重層コンデンサの電力を出力し、該二次電池の放電電圧が該電気二重層コンデンサの放電電圧がより高いときは、該第２の逆流防止用素子をオン状態にして該二次電池の電力を出力する出力切替え手段とを備え、交流電源の電力低下時に、上記電気二重層コンデンサの放電電圧が上記二次電池の放電電圧よりも高い間は、該電気二重層コンデンサから負荷側に電力を供給し、該電気二重層コンデンサの放電電圧が下がり該二次電池の放電電圧よりも低くなったときは、該二次電池から該負荷側に電力を供給する構成とする。（４）交流電源からの交流電力を直流電力に変換するＡＣ／ＤＣコンバータと、第１のエネルギー蓄積手段としての電気二重層コンデンサと、第２のエネルギー蓄積手段としての二次電池と、該二次電池を充電する充電手段と、上記電気二重層コンデンサに直列接続された第１の逆流防止用素子と、上記二次電池に直列接続されかつ上記第１の逆流防止用素子に並列接続された第２の逆流防止用素子と、上記第１、第２の逆流防止用素子と負荷との間に接続され、上記電気二重層コンデンサまたは上記二次電池からの電力を負荷供給用電力に変換する電力変換手段とを備え、上記電気二重層コンデンサの放電電圧と上記二次電池の放電電圧の差に基づき、上記第１の逆流防止用素子または上記第２の逆流防止用素子をオン状態にして上記電気二重層コンデンサまたは上記二次電池の電力を負荷側に供給可能にするとともに、該電気二重層コンデンサの電力を供給しているときは上記二次電池を充電し、上記電力変換手段がオフ状態のときは上記二次電池及び上記電気二重層コンデンサを充電する構成とする。（５）上記（１）から（４）のいずれかにおいて、上記第１逆流防止用素子及び上記第２の逆流防止用素子をダイオードとする。
上記構成により、上記逆流防止用素子は放電条件にあったエネルギー蓄積手段を選択する。交流電源の電力低下が瞬時に発生した場合は、最初に、短時間のバックアップに適した電気二重層コンデンサを選択して負荷側への電力供給を行わせ、停電時のように長時間にわたって交流電源からの電力供給が断たれ、かつ負荷側への供給電力が大きい場合には、最初のうちは放電電圧の高い電気二重層コンデンサを選択して負荷側への電力供給を行わせ、該電気二重層コンデンサの放電電圧が下がり、二次電池の放電電圧よりも低くなった時点で該二次電池を選択し、該二次電池からの電力供給に切替える。
【０００６】
【発明の実施の形態】
以下、本発明の実施例につき、図面を用いて説明する。
図１〜図５は、本発明の無停電電源装置における実施例の説明図である。図１は無停電電源装置の回路構成例を示す図、図２はエネルギー蓄積手段の充電の動作説明図、図３はエネルギー蓄積手段の充電と出力の動作説明図、図４はエネルギー蓄積手段の放電の動作説明図、図５はエネルギー蓄積手段の切替えと放電特性との関係の説明図である。
図１において、１は、例えば交流１００Ｖの単相交流電源を直流電圧・電流に変換するＡＣ／ＤＣコンバータ、２は、二次電池の充電を行う充電回路、３は第２のエネルギー蓄積手段としての二次電池、４は第１のエネルギー蓄積手段としての電気二重層コンデンサ、５は電気二重層コンデンサ４の出力と二次電池３の出力とを選択的に切替えて負荷側に出力する出力切替え手段、７ａは第１の逆流防止用素子としての第１のダイオード、７ｂは第２の逆流防止用素子としての第２のダイオード、６は、直流電圧・電流を所定の直流出力に変換する電力変換手段としてのＤＣ／ＤＣコンバータ、２１は電流検出用抵抗である。第１のダイオード７ａは電気二重層コンデンサ４に直列に接続され、第２のダイオード７ｂは二次電池３に直列に接続されている。電気二重層コンデンサ４と第１のダイオード７ａの直列回路は第１の電力供給系を形成し、二次電池３と第２のダイオード７ｂの直列回路は第２の電力供給系を形成する。第１のダイオード７ａ、第２のダイオード７ｂの出力側は互いに接続（ダイオードＯＲ接続）され、これによって、上記第１の電力供給系と上記第２の電力供給系が互いに、負荷に対して並列接続される。出力切替え手段５は、第１のダイオード７ａと第２のダイオード７ｂとの並列接続（ＯＲ接続）によって構成される。ＡＣ／ＤＣコンバータ１は、ダイオードブリッジ、トランス、トランジスタによるスイッチング素子、及びコンデンサなどから構成される。Ｐａは該ＡＣ／ＤＣコンバータ１の出力である。充電回路２は、負荷の状況に応じて二次電池３への充電電圧、充電電流を制御する充電制御ＩＣやマイコンなどから構成され、二次電池３を過充電から保護する機能も有する。Ｐｂは該充電回路２の出力である。二次電池３は、ニッケルカドミウム電池、ニッケル水素電池、リチウムイオン電池など充電可能な電池を複数個直列または並列に接続して構成される。Ｖｂは該二次電池３の放電電圧である。電気二重層コンデンサ４は、１個構成でも複数個を接続して成る構成でもよい。Ｖｃは該電気二重層コンデンサ４の放電電圧、Ｐｃ該電気二重層コンデンサ４の電力である。二次電池３及び電気二重層コンデンサ４については、個々の耐圧性能、容量、接続数等は、装置仕様に対応したものとする他、電気二重層コンデンサ４の放電電圧Ｖｃと二次電池３の放電電圧Ｖｂとの関係が、Ｖｃ＞Ｖｂを満たすようにする。ＤＣ／ＤＣコンバータ６は、トランジスタから成る複数のスイッチング素子やコンデンサ等から構成される。Ｐｄは該ＤＣ／ＤＣコンバータ６の出力電力である。電気二重層コンデンサ４は、電極に活性炭を使用し、活性炭表面と電解液の間に生じる電気二重層現象を利用したコンデンサであり、構成材料により、１セル当りの静電容量を数Ｆ〜数百Ｆにすることができる小形で大容量のコンデンサである。二次電池３では、充電のためには充電回路２が必要であるが、該電気二重層コンデンサ４では充電回路２が不要であり、過放電による寿命への影響もない。また、完全放電した場合も、極めて短時間で再充電を行うことが可能である。さらに、該電気二重層コンデンサ４は、充放電を繰り返しても劣化がほとんどない。これに対し、二次電池は、充放電の繰り返しによるサイクル寿命は、放電の深度にもよるが、通常は５００〜１０００回程度である。また、該二次電池３が鉛蓄電池、ニッケルカドミウム電池、ニッケル水素電池の場合は、浅い放電を繰り返すことに起因した電池容量の減少（メモリー効果）があり、これが寿命に影響する。このため、図１の回路構成において、停電時間が短時間（数ｓ〜ｍｉｎ程度）で、負荷の所要出力が少ない場合は、電気二重層コンデンサ４に蓄えられたエネルギーを電力として負荷に供給することにより、二次電池３は浅い放電を繰り返さずに済む。このため、二次電池３の寿命を大幅に伸ばすことが可能となり、メンテナンスの工数を低減できるようになる。
【０００７】
図２は、図１の構成においてＤＣ／ＤＣコンバータ６の出力が停止している場合における二次電池３と電気二重層コンデンサ４の充電の動作説明図である。
図２において、（１）交流入力電源からの電力供給が正常に行われ（ステップＳ２０１）、ＤＣ／ＤＣコンバータ６の出力が停止している場合、ＡＣ／ＤＣコンバータ１より出力された電力Ｐａは、充電回路２を介し、二次電池３を充電する電力Ｐｂと電気二重層コンデンサ４に充電される電力Ｐｃとに分けられる（ステップＳ２０２）。（２）電気二重層コンデンサ４は、充電時間が、二次電池３よりも大幅に短い。このため、該電気二重層コンデンサ４の充電（ステップＳ２０３）が二次電池３の充電（ステップＳ２０４、ステップＳ２０５）より先に終了する。（３）電気二重層コンデンサ４の充電終了により、二次電池３の充電は、ＡＣ／ＤＣコンバータ１の能力範囲内で二次電池３が許容できる最大電流での充電（ステップＳ２０６）に移行する。（４）充電回路２には、二次電池３の過充電を保護する回路を設けてあり、二次電池３の充電が終了したら二次電池３への充電電流の供給を停止させ充電を終らせる（ステップＳ２０７）。
【０００８】
図３は、図１の構成においてＤＣ／ＤＣコンバータ６の出力がある場合における二次電池３と電気二重層コンデンサ４の充電の動作説明図である。
図３において、（１）入力電源からの供給が正常に行われ（ステップＳ３０１）、ＤＣ／ＤＣコンバータ６の出力があり、二次電池３の充電が十分な場合（ステップＳ３０３）は、ＡＣ／ＤＣコンバータ１より出力された（ステップＳ３０２）電力Ｐａは、電気二重層コンデンサ４を介し、ＤＣ／ＤＣコンバータ６へ供給される（ステップＳ３０４、ステップＳ３０６、ステップＳ３０７）。（２）二次電池３の充電が十分でない場合（ステップＳ３０３）、充電回路２は、電流検出用抵抗２１より、回路に流れる電流を検出するとともに、二次電池３の充電のために充電回路２自身に流れる電流をも検出し、ＤＣ／ＤＣコンバータ６への出力の負荷電力Ｐｄの状況に応じ、ＡＣ／ＤＣコンバータ１が供給可能な電力Ｐａから、ＤＣ／ＤＣコンバータ６へ出力される最大電力Ｐｄを引いた残りの電力で二次電池３を充電する（ステップＳ３０３、ステップＳ３０５、ステップＳ３０６、ステップＳ３０７、ステップＳ３０８、ステップＳ３０９）。
入力電源からの供給が正常に行われ、ＤＣ／ＤＣコンバータ６の出力が負荷電力Ｐｄのレベルが急激な増加により変動が激しい場合、ＡＣ／ＤＣコンバータ１の供給能力次第では、ＤＣ／ＤＣコンバータ６へ入力される電圧の降下や瞬間的な電力の停止が発生する場合があるが、この場合は、ＡＣ／ＤＣコンバータ１の出力を介して接続された電気二重層コンデンサ４に蓄えられた電力Ｐｃを放電することにより電源の変動を抑制することが可能となる。
【０００９】
図４は、図１の構成において交流入力電源からの供給が停電などで停止した場合における二次電池３と電気二重層コンデンサ４の放電の動作説明図である。
図４において、（１）交流入力電源からの供給が停電などで停止し（ステップＳ４０１）、ＡＣ／ＤＣコンバータ１の出力が停止した場合（ステップＳ４０２）は、まず、電気二重層コンデンサ４に蓄積された電力Ｐｃが放電され（ステップＳ４０３）、（２）次に、二次電池３に蓄積された電力ＰｂをＤＣ／ＤＣコンバータ６を介し負荷へ供給する。停電時間が短時間（数ｓ〜２ｍｉｎ程度）で、かつ負荷への出力が少ない場合は、電気二重層コンデンサ４に蓄積された電力Ｐｃでまかなう。負荷が大きく、かつ長時間（２ｍｉｎ〜１０ｍｉｎ）電力を供給しなければならない場合は、電気二重層コンデンサ４に蓄積された電力Ｐｃを放電した後、二次電池３に蓄積された電力ＰｂをＤＣ／ＤＣコンバータ６に供給する（ステップＳ４０５）。出力切替え手段５では、逆流防止用の第１のダイオード７ａと第２のダイオード７ｂによるダイオードＯＲ接続の作用により、電気二重層コンデンサ４の放電電圧Ｖｃと二次電池３の放電電圧Ｖｂとの電位差で切替えが制御される（ステップＳ４０４）。すなわち、Ｖｃ＞Ｖｂのときは、第１のダイオード７ａがオン状態となり、電気二重層コンデンサ４に蓄積された電力ＰｃがＤＣ／ＤＣコンバータ６に供給され、変換された出力がＤＣ／ＤＣコンバータ６から出力される（ステップＳ４０３、ステップＳ４０４、ステップＳ４０６、ステップＳ４０７）。また、放電により該電気二重層コンデンサ４の放電電圧が低下してＶｃ＜Ｖｂとなったときは、第２のダイオード７ｂがオン状態となり、二次電池３に蓄積された電力ＰｂがＤＣ／ＤＣコンバータ６に供給され、変換された出力がＤＣ／ＤＣコンバータ６から出力される（ステップＳ４０４、ステップＳ４０５、ステップＳ４０６、ステップＳ４０７）。
【００１０】
図５は、上記図４の切替え動作時の二次電池３と電気二重層コンデンサ４の放電特性例を示す図である。出力切替え点ｃでエネルギー蓄積手段が電気二重層コンデンサ４から二次電池３に切替わる。
【００１１】
上記実施例構成によれば、頻繁に発生する交流電源の短時間の電力低下に対しては、サイクル寿命が半永久的な電気二重層コンデンサ４でバックアップし、停電時に発生する交流電源の長時間の電力低下に対しては、電気容量が大きい二次電池３でバックアップすることができる。二次電池３と電気二重層コンデンサ４の切替えも自動的にかつ容易に行うことができる。電気二重層コンデンサ４でバックアップ対応することにより、二次電池３の寿命を延ばすことができ、電池交換などのメンテナンスをなくすことも可能となる。また、二次電池３でバックアップ対応することにより、電気二重層コンデンサ４の容量が小さくて済み、このため、無停電電源装置の寸法の増大化を抑えられる。また、負荷への供給時間を延ばすこともできる。短い充電時間で対応可能となる。バックアップの大容量化も可能となる。エネルギー蓄積手段相互間での充電電流の流れを抑えることができる。回路の破壊や異常発熱の発生を防止することができる。
【００１２】
なお、本発明は上記実施例に限定されるものではない。例えば、上記実施例では、電力変換手段としてのＤＣ／ＤＣコンバータ６から、直流駆動用負荷に対し、電力を供給する構成としたが、本発明はこれに限定されず、例えば、電力変換手段としてＤＣ／ＡＣコンバータを用い、これから交流駆動用負荷に対し電力を供給するようにしてもよい。
【００１３】
【発明の効果】
本発明によれば、無停電電源装置において、バックアップの長時間化が可能となる。メンテナンスの工数低減化も可能となる。装置の大型化も抑えられる。
【図面の簡単な説明】
【図１】本発明の実施例としての無停電電源装置の回路構成例を示す図である。
【図２】図１のエネルギー蓄積手段の充電の動作説明図である。
【図３】図１のエネルギー蓄積手段の充電と出力の動作説明図である。
【図４】図１のエネルギー蓄積手段の放電の動作説明図である。
【図５】図１のエネルギー蓄積手段の切替えと放電特性との関係の説明図である。
【符号の説明】
１…ＡＣ／ＤＣコンバータ、２…充電回路、３…二次電池、４…電気二重層コンデンサ、５…出力切替え手段、６…ＤＣ／ＤＣコンバータ、７ａ、７ｂ…ダイオード、２１…電流検出用抵抗。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an uninterruptible power supply that supplies power from an energy storage unit such as a secondary battery to an electronic device such as a computer-related device or a product as a load when the power of an AC power supply decreases.
[0002]
[Prior art]
As a technique for supplying power from the energy storage means to the load side when the power of the AC power supply is reduced, for example, Japanese Patent Application Laid-Open No. 2000-184758 (Patent Document 1), Japanese Patent Application Laid-Open No. 9-308135 (Patent Document 2), and There is one described in Japanese Unexamined Patent Publication No. 2000-139041 (Patent Document 3). Japanese Patent Application Laid-Open No. 2000-184752 discloses that in order to provide a small and inexpensive uninterruptible power supply without changing the structure or shape of a transformer or a storage battery, an inverter configuration for an inverter is provided on the storage battery in the device casing. It describes a configuration in which a board on which a switching element is mounted is arranged, and a transformer is arranged above the board. Japanese Patent Application Laid-Open No. 9-308135 discloses that an electric double layer capacitor is provided when the voltage of an AC power supply is reduced, in order to suppress an increase in the size of the device, provide an energy storage unit having a long output holding time during a power failure and a short charging time. It describes a configuration used in place of an electric field capacitor or a battery. JP-A-2000-139041 discloses that a single device can supply a steady-state uninterruptible power supply current supplied to an onboard load and an instantaneous large current supplied to a diesel engine start motor (reference numeral 6). In order to provide a marine power supply device, a secondary battery (reference numeral 2) and an electric double layer capacitor (reference numeral 1) are connected in parallel, and a load (reference numeral) is provided between the secondary battery and the onboard load. A configuration is described in which a parallel circuit of a rectifier (reference numeral 3) whose forward direction is a current flowing through 11) and a resistor (reference numeral 4) is connected. An overcurrent breaker (reference numeral 5) is connected in series to the resistor.
[0003]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2000-184758 [Patent Document 2]
JP-A-9-308135 [Patent Document 3]
Japanese Patent Application Laid-Open No. 2000-139041
[Problems to be solved by the invention]
Among the above-mentioned prior arts, the technology described in Japanese Patent Application Laid-Open No. 2000-184755 has a configuration using a storage battery as an energy storage means. With this configuration alone, the service life is generally short, and charging after discharging requires a long time. The technique described in Japanese Patent Application Laid-Open No. 9-308135 has a configuration using an electric double layer capacitor as energy storage means, and generally has a short output holding time during a power failure. For this reason, for long-term backup, it is necessary to increase the capacity of the electric double layer capacitor, which may increase the size of the device. Further, the technique described in Japanese Patent Application Laid-Open No. 2000-139041 simply connects a secondary battery and an electric double layer capacitor in parallel as an energy storage means, and a parallel circuit of a rectifier 3 and a resistor 4 is provided on the subsequent stage of the parallel connection point. It is a configuration provided. For this reason, a charging current flows from the secondary battery 2 to the electric double layer capacitor 1 due to a difference between the voltage and the internal resistance value of the secondary battery 2 and the electric double layer capacitor 1, and the secondary battery 2 is discharged. As a result, an abrupt charging current flows through the circuit, and the current may exceed the rated current of the circuit, which may cause destruction of the circuit or abnormal heat generation.
In view of the state of the prior art described above, the problems of the present invention are that in an uninterruptible power supply, (1) the life of a secondary battery can be extended, (2) the device can be configured not to be enlarged, and (3) short charging (4) to be able to reduce maintenance man-hours, (5) to be able to prevent charging current from flowing between the energy storage means even when a plurality of energy storage means are used, (6) The configuration is such that circuit destruction and abnormal heat generation do not occur.
An object of the present invention is to provide a technique capable of solving such a problem.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, in the present invention, basically, in an uninterruptible power supply, a secondary battery and an electric double layer capacitor are used as energy storage means, and a backflow preventing element such as a diode is connected to each of them in series. The connected circuits are connected in parallel with each other, and when the discharge voltage of the electric double layer capacitor is higher than the discharge voltage of the secondary battery when the power of the AC power source is reduced, a backflow prevention on the electric double layer capacitor side is performed. The element is turned on to supply the electric power of the electric double layer capacitor to the load side, and when the discharge voltage of the electric double layer capacitor decreases and becomes lower than the discharge voltage of the secondary battery, the secondary battery side Is turned on to supply the power of the secondary battery to the load side. More specifically, the uninterruptible power supply (1) includes an electric double layer capacitor and a secondary battery as energy storage means, and a first backflow prevention element connected in series to the electric double layer capacitor. 1 power supply system, and a second power supply system in which a second backflow prevention element is connected in series to the secondary battery, wherein the electric double-layer capacitor and the discharge voltage of the secondary battery are measured. By switching from the ON state of the first backflow prevention element to the ON state of the second backflow prevention element based on the difference, the power supply to the load is supplied by the first power supply system. From the second power supply system. (2) A first power supply system in which a first backflow preventing element is connected in series to an electric double layer capacitor as first energy storage means, and a second power supply system in which a second battery is used as second energy storage means. And a second power supply system connected in series with the backflow preventing element is connected in parallel, and when the discharge voltage of the electric double layer capacitor is higher than the discharge voltage of the secondary battery, the first backflow prevention And turning on the power supply element to supply power of the electric double layer capacitor to the load side from the first power supply system, and the discharge voltage of the electric double layer capacitor is lowered to be lower than the discharge voltage of the secondary battery. When this happens, the second backflow prevention element is turned on so that the power of the secondary battery can be supplied from the second power supply system to the load side. (3) an electric double layer capacitor as first energy storage means, a secondary battery as second energy storage means, a first backflow preventing element connected in series to the electric double layer capacitor, A second backflow prevention element connected in series to the secondary battery has a configuration connected in parallel to each other, and when the discharge voltage of the electric double layer capacitor is higher than the discharge voltage of the secondary battery, The first backflow prevention element is turned on to output the electric power of the electric double layer capacitor. When the discharge voltage of the secondary battery is higher than the electric double layer capacitor, the second reverse current Output switching means for outputting the power of the secondary battery by turning on the prevention element, wherein when the power of the AC power source is reduced, the discharge voltage of the electric double layer capacitor is higher than the discharge voltage of the secondary battery. Between the electricity A configuration in which power is supplied from the multilayer capacitor to the load side, and when the discharge voltage of the electric double layer capacitor decreases and becomes lower than the discharge voltage of the secondary battery, power is supplied from the secondary battery to the load side. And (4) an AC / DC converter for converting AC power from an AC power supply into DC power, an electric double layer capacitor as first energy storage means, a secondary battery as second energy storage means, Charging means for charging the secondary battery, a first backflow prevention element connected in series to the electric double layer capacitor, and a series connection to the secondary battery and a parallel connection to the first backflow prevention element A second backflow prevention element is connected between the first and second backflow prevention elements and the load, and converts power from the electric double layer capacitor or the secondary battery into load supply power. Power conversion means, based on a difference between the discharge voltage of the electric double layer capacitor and the discharge voltage of the secondary battery, turning on the first backflow preventing element or the second backflow preventing element, Above electricity The power of the multilayer capacitor or the secondary battery can be supplied to the load side, and when the power of the electric double layer capacitor is being supplied, the secondary battery is charged, and the power conversion unit is in an off state. Is configured to charge the secondary battery and the electric double layer capacitor. (5) In any one of the above (1) to (4), the first backflow prevention element and the second backflow prevention element are diodes.
With the above configuration, the backflow prevention element selects an energy storage unit that meets the discharge conditions. If the power supply of the AC power source instantaneously drops, first select an electric double layer capacitor suitable for short-time backup and supply power to the load side. If the power supply from the power supply is interrupted and the power supply to the load side is large, initially select an electric double layer capacitor with a high discharge voltage to supply power to the load side, and When the discharge voltage of the double-layer capacitor drops and becomes lower than the discharge voltage of the secondary battery, the secondary battery is selected, and the power supply from the secondary battery is switched.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 5 are explanatory diagrams of an embodiment of the uninterruptible power supply according to the present invention. FIG. 1 is a diagram showing an example of a circuit configuration of an uninterruptible power supply, FIG. 2 is an explanatory diagram of an operation of charging the energy storage device, FIG. 3 is an explanatory diagram of an operation of charging and output of the energy storage device, and FIG. FIG. 5 is an explanatory diagram of a discharge operation, and FIG. 5 is an explanatory diagram of a relationship between switching of energy storage means and discharge characteristics.
In FIG. 1, 1 is an AC / DC converter for converting a single-phase AC power supply of, for example, 100 V AC to DC voltage / current, 2 is a charging circuit for charging a secondary battery, and 3 is a second energy storage means. 4 is an electric double layer capacitor as a first energy storage means, 5 is an output switch for selectively switching between the output of the electric double layer capacitor 4 and the output of the secondary battery 3 and outputting to the load side. Means, 7a is a first diode as a first backflow preventing element, 7b is a second diode as a second backflow preventing element, 6 is a power for converting a DC voltage / current into a predetermined DC output. A DC / DC converter as conversion means, 21 is a current detecting resistor. The first diode 7a is connected in series to the electric double layer capacitor 4, and the second diode 7b is connected in series to the secondary battery 3. A series circuit of the electric double layer capacitor 4 and the first diode 7a forms a first power supply system, and a series circuit of the secondary battery 3 and the second diode 7b forms a second power supply system. The output sides of the first diode 7a and the second diode 7b are connected to each other (diode OR connection), so that the first power supply system and the second power supply system are parallel to each other with respect to the load. Connected. The output switching means 5 is configured by a parallel connection (OR connection) of the first diode 7a and the second diode 7b. The AC / DC converter 1 includes a diode bridge, a transformer, a switching element including a transistor, a capacitor, and the like. Pa is the output of the AC / DC converter 1. The charging circuit 2 includes a charge control IC for controlling a charging voltage and a charging current for the secondary battery 3 according to a load condition, a microcomputer, and the like, and also has a function of protecting the secondary battery 3 from overcharging. Pb is the output of the charging circuit 2. The secondary battery 3 is configured by connecting a plurality of rechargeable batteries such as a nickel cadmium battery, a nickel hydride battery, and a lithium ion battery in series or parallel. Vb is a discharge voltage of the secondary battery 3. The electric double layer capacitor 4 may have a single configuration or a configuration in which a plurality of components are connected. Vc is the discharge voltage of the electric double layer capacitor 4, and Pc is the power of the electric double layer capacitor 4. Regarding the secondary battery 3 and the electric double layer capacitor 4, the individual withstand voltage performance, capacity, number of connections, and the like correspond to the device specifications, and the discharge voltage Vc of the electric double layer capacitor 4 and the The relationship with the discharge voltage Vb is set to satisfy Vc> Vb. The DC / DC converter 6 includes a plurality of switching elements including transistors, capacitors, and the like. Pd is the output power of the DC / DC converter 6. The electric double layer capacitor 4 is a capacitor that uses activated carbon as an electrode and utilizes an electric double layer phenomenon that occurs between the surface of the activated carbon and the electrolytic solution. It is a small, large-capacity capacitor that can be set to 100F. The secondary battery 3 requires the charging circuit 2 for charging, but the electric double layer capacitor 4 does not require the charging circuit 2 and does not affect the life due to overdischarge. Further, even when the battery is completely discharged, recharging can be performed in a very short time. Further, the electric double layer capacitor 4 hardly deteriorates even if charge and discharge are repeated. On the other hand, the cycle life of a secondary battery due to repetition of charge and discharge depends on the depth of discharge, but is generally about 500 to 1000 times. When the secondary battery 3 is a lead storage battery, a nickel cadmium battery, or a nickel hydride battery, there is a reduction in battery capacity (memory effect) due to repeated shallow discharges, which affects the life. Therefore, in the circuit configuration of FIG. 1, when the power outage time is short (about several s to min) and the required output of the load is small, the energy stored in the electric double layer capacitor 4 is supplied to the load as electric power. Thereby, the secondary battery 3 does not need to repeat shallow discharge. For this reason, the life of the secondary battery 3 can be greatly extended, and the number of maintenance steps can be reduced.
[0007]
FIG. 2 is a diagram illustrating the operation of charging the secondary battery 3 and the electric double layer capacitor 4 when the output of the DC / DC converter 6 is stopped in the configuration of FIG.
In FIG. 2, (1) when the power supply from the AC input power supply is performed normally (step S201) and the output of the DC / DC converter 6 is stopped, the power Pa output from the AC / DC converter 1 becomes Is divided into power Pb for charging the secondary battery 3 and power Pc for charging the electric double layer capacitor 4 via the charging circuit 2 (step S202). (2) The charging time of the electric double layer capacitor 4 is much shorter than that of the secondary battery 3. Therefore, the charging of the electric double layer capacitor 4 (Step S203) is completed before the charging of the secondary battery 3 (Step S204, Step S205). (3) When the charging of the electric double layer capacitor 4 is completed, the charging of the secondary battery 3 shifts to charging with the maximum current allowable for the secondary battery 3 within the capability range of the AC / DC converter 1 (step S206). . (4) The charging circuit 2 is provided with a circuit for protecting the secondary battery 3 from overcharging. When the charging of the secondary battery 3 is completed, the supply of the charging current to the secondary battery 3 is stopped to terminate the charging. (Step S207).
[0008]
FIG. 3 is an explanatory diagram of the charging operation of the secondary battery 3 and the electric double layer capacitor 4 when the output of the DC / DC converter 6 is present in the configuration of FIG.
In FIG. 3, (1) when the supply from the input power supply is performed normally (step S301), the output of the DC / DC converter 6 is present, and when the rechargeable battery 3 is sufficiently charged (step S303), The power Pa output from the DC converter 1 (step S302) is supplied to the DC / DC converter 6 via the electric double layer capacitor 4 (step S304, step S306, step S307). (2) When the charging of the secondary battery 3 is not sufficient (Step S303), the charging circuit 2 detects the current flowing through the circuit from the current detection resistor 21 and also charges the charging circuit for charging the secondary battery 3. 2 also detects the current flowing through itself and, depending on the load power Pd output to the DC / DC converter 6, changes the maximum power output to the DC / DC converter 6 from the power Pa that can be supplied by the AC / DC converter 1. The secondary battery 3 is charged with the remaining power after subtracting the power Pd (Step S303, Step S305, Step S306, Step S307, Step S308, Step S309).
When the supply from the input power supply is performed normally and the output of the DC / DC converter 6 fluctuates greatly due to a sudden increase in the level of the load power Pd, depending on the supply capacity of the AC / DC converter 1, the DC / DC converter 6 In some cases, the voltage Pc stored in the electric double-layer capacitor 4 connected via the output of the AC / DC converter 1 may be dropped. , The fluctuation of the power supply can be suppressed.
[0009]
FIG. 4 is an explanatory diagram of an operation of discharging the secondary battery 3 and the electric double layer capacitor 4 when the supply from the AC input power supply is stopped due to a power failure or the like in the configuration of FIG.
In FIG. 4, (1) when the supply from the AC input power supply is stopped due to a power failure or the like (step S401), and when the output of the AC / DC converter 1 is stopped (step S402), first, the electric double layer capacitor 4 accumulates. The discharged power Pc is discharged (step S403). (2) Next, the power Pb stored in the secondary battery 3 is supplied to the load via the DC / DC converter 6. When the power outage time is short (several seconds to about 2 minutes) and the output to the load is small, the power Pc stored in the electric double layer capacitor 4 is sufficient. When the load is large and power must be supplied for a long time (2 min to 10 min), after discharging the power Pc stored in the electric double layer capacitor 4, the power Pb stored in the secondary battery 3 is converted to DC. / DC converter 6 (step S405). In the output switching means 5, the potential difference between the discharge voltage Vc of the electric double layer capacitor 4 and the discharge voltage Vb of the secondary battery 3 is caused by the action of the diode OR connection of the first diode 7 a and the second diode 7 b for backflow prevention. The switching is controlled by (step S404). That is, when Vc> Vb, the first diode 7a is turned on, the power Pc stored in the electric double layer capacitor 4 is supplied to the DC / DC converter 6, and the converted output is supplied to the DC / DC converter 6 (Step S403, Step S404, Step S406, Step S407). Further, when the discharge voltage of the electric double layer capacitor 4 decreases due to the discharge and Vc <Vb, the second diode 7b is turned on, and the power Pb stored in the secondary battery 3 is reduced to DC / DC. The output that is supplied to the converter 6 and converted is output from the DC / DC converter 6 (step S404, step S405, step S406, and step S407).
[0010]
FIG. 5 is a diagram showing an example of the discharge characteristics of the secondary battery 3 and the electric double layer capacitor 4 during the switching operation of FIG. At the output switching point c, the energy storage means switches from the electric double layer capacitor 4 to the secondary battery 3.
[0011]
According to the configuration of the above embodiment, the short-term power reduction of the AC power supply that frequently occurs is backed up by the electric double layer capacitor 4 whose cycle life is semi-permanent, and the AC power supply that occurs at the time of the power failure has a long time. When the power is reduced, it can be backed up by the secondary battery 3 having a large electric capacity. Switching between the secondary battery 3 and the electric double layer capacitor 4 can also be performed automatically and easily. By providing backup with the electric double layer capacitor 4, the life of the secondary battery 3 can be extended, and maintenance such as battery replacement can be eliminated. In addition, since the secondary battery 3 supports backup, the capacity of the electric double-layer capacitor 4 can be reduced, and therefore, an increase in the size of the uninterruptible power supply can be suppressed. Further, the supply time to the load can be extended. It is possible to respond in a short charging time. Backup capacity can be increased. The flow of the charging current between the energy storage means can be suppressed. The destruction of the circuit and the occurrence of abnormal heat generation can be prevented.
[0012]
The present invention is not limited to the above embodiment. For example, in the above-described embodiment, the DC / DC converter 6 as the power conversion means supplies power to the DC driving load. However, the present invention is not limited to this. A DC / AC converter may be used to supply power to an AC drive load.
[0013]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, in an uninterruptible power supply, backup can be lengthened. Maintenance man-hours can also be reduced. The size of the apparatus can be suppressed.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a circuit configuration of an uninterruptible power supply as an embodiment of the present invention.
FIG. 2 is an explanatory diagram of a charging operation of the energy storage means of FIG. 1;
FIG. 3 is an operation explanatory diagram of charging and output of the energy storage means of FIG. 1;
FIG. 4 is a diagram illustrating the operation of discharging the energy storage means of FIG. 1;
FIG. 5 is an explanatory diagram of a relationship between switching of the energy storage unit of FIG. 1 and discharge characteristics.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... AC / DC converter, 2 ... Charge circuit, 3 ... Secondary battery, 4 ... Electric double layer capacitor, 5 ... Output switching means, 6 ... DC / DC converter, 7a, 7b ... Diode, 21 ... Current detection resistance .

Claims

In an uninterruptible power supply that can supply power from the energy storage means to the load side when the power of the AC power supply decreases,
A first power supply system having an electric double layer capacitor and a secondary battery as energy storage means, a first backflow prevention element connected in series to the electric double layer capacitor, and a second power supply system connected to the secondary battery. And a second power supply system connected in series with the backflow preventing element is connected in series, and based on a difference between the electric double layer capacitor and the discharge voltage of the secondary battery, the first backflow preventing element is turned on. By switching from the state to the ON state of the second backflow prevention element, power supply to the load can be switched from supply by the first power supply system to supply by the second power supply system. An uninterruptible power supply device having a configuration.

In an uninterruptible power supply that can supply power from the energy storage means to the load side when the power of the AC power supply decreases,
A first power supply system in which a first backflow prevention element is connected in series to an electric double layer capacitor as first energy storage means, and a second backflow prevention in a secondary battery as second energy storage means A second power supply system connected in series with the power supply element, and when the discharge voltage of the electric double layer capacitor is higher than the discharge voltage of the secondary battery, the first backflow prevention element is provided. When the power of the electric double layer capacitor is supplied to the load side from the first power supply system in the ON state, and the discharge voltage of the electric double layer capacitor drops and becomes lower than the discharge voltage of the secondary battery. Is an uninterruptible power supply characterized in that the second backflow prevention element is turned on so that the power of the secondary battery can be supplied to the load side from the second power supply system.

In an uninterruptible power supply that can supply power from the energy storage means to the load side when the power of the AC power supply decreases,
An electric double layer capacitor as first energy storage means,
A secondary battery as a second energy storage means,
The electric double layer capacitor has a configuration in which a first backflow prevention element connected in series to the electric double layer capacitor and a second backflow prevention element connected in series to the secondary battery are connected in parallel with each other. When the discharge voltage of the multilayer capacitor is higher than the discharge voltage of the secondary battery, the first backflow prevention element is turned on to output power of the electric double layer capacitor, and the discharge voltage of the secondary battery is reduced. When the discharge voltage of the electric double layer capacitor is higher, output switching means for outputting the power of the secondary battery by turning on the second backflow prevention element,
When the discharge voltage of the electric double layer capacitor is higher than the discharge voltage of the secondary battery when the power of the AC power supply decreases, power is supplied from the electric double layer capacitor to the load side, and the electric double layer An uninterruptible power supply device, wherein when the discharge voltage of the capacitor decreases and becomes lower than the discharge voltage of the secondary battery, power is supplied from the secondary battery to the load side.

In an uninterruptible power supply that can supply power from the energy storage means to the load side when the power of the AC power supply decreases,
An AC / DC converter for converting AC power from an AC power supply into DC power;
An electric double layer capacitor as first energy storage means,
A secondary battery as a second energy storage means,
Charging means for charging the secondary battery;
A first backflow prevention element connected in series to the electric double layer capacitor;
A second backflow prevention element connected in series to the secondary battery and connected in parallel to the first backflow prevention element;
Power conversion means connected between the first and second backflow prevention elements and a load, and converting power from the electric double layer capacitor or the secondary battery into load supply power;
And turning on the first backflow preventing element or the second backflow preventing element based on a difference between a discharge voltage of the electric double layer capacitor and a discharge voltage of the secondary battery. The power of the multilayer capacitor or the secondary battery can be supplied to the load side, and when the power of the electric double layer capacitor is being supplied, the secondary battery is charged, and the power conversion unit is in an off state. Is an uninterruptible power supply characterized in that said secondary battery and said electric double layer capacitor are charged.

The uninterruptible power supply according to any one of claims 1 to 4, wherein the first backflow prevention element and the second backflow prevention element are diodes.