JP4349773B2

JP4349773B2 - Battery charging method and backup power supply apparatus for implementing the charging method

Info

Publication number: JP4349773B2
Application number: JP2002109925A
Authority: JP
Inventors: 芳秀高橋; 昌弘濱荻; 節田邉; 隆雄後藤; 玲彦叶田; 峰弘根本; 史一高橋
Original assignee: Hitachi Computer Peripherals Co Ltd; Hitachi Ltd
Current assignee: Hitachi Ltd; Hitachi Information and Telecommunication Engineering Ltd
Priority date: 2002-04-12
Filing date: 2002-04-12
Publication date: 2009-10-21
Anticipated expiration: 2022-04-12
Also published as: JP2003309933A

Description

【０００１】
【産業上の利用分野】
本発明は、電源装置における無停電を行うためのバッテリへのバッテリ充電方法及び、該充電方法を実施するバックアップ電源装置に係り、特にＡＣ／ＤＣ変換部に負荷を与えずに好適にバッテリ充電を行うことができるバッテリ充電方法及び該充電方法を実施するバックアップ電源装置に関する。
【０００２】
【従来の技術】
一般にコンピュータシステムにおける周辺装置は、定電源を確保するための電源装置と停電時に対応するための無停電装置（ＵＰＳ）が接続されている。この従来技術による電源システムは、図２に示す如く、交流電源２００から電流Ｉin及び電圧Ｖinから成る電力を入力としてバッテリ充電を行う無停電装置５００と、該無停電装置５００からの交流電圧を直流電圧に変換して負荷装置３００に出力する電源装置１００とから構成され、前記無停電装置５００は、入力電圧ＶinをＡＣ／ＤＣ変換部１により直流電圧に変換し、電圧Ｖ_１をＤＣ／ＡＣ変換部２により交流に戻してから次段の電源装置１００に供給すると共に電流Ｉ_２を充放電回路３を介してバッテリ４に充電するものであり、電源装置１００は、無停電装置５００からの交流電圧をＡＣ／ＤＣ変換部１０１により直流に変換し、更にＤＣ／ＤＣ変換部１０２により所定電圧の直流電流を負荷装置３００に供給する様に構成され、充放電回路３がＡＣ／ＤＣ変換部１の出力から指定されたワット数の電力をバッテリ４に充電する様に構成されている。
【０００３】
【発明が解決しようとする課題】
この様に構成された電源システムは、負荷装置３００の必要とする電力によって電流値が変化するため、ＡＣ／ＤＣ変換部及びＤＣ／ＤＣ変換部の容量を、負荷装置の必要とする電流に応じて大容量に設計する必要があると言う不具合があった。例えば負荷装置が複数の磁気ディスク装置が接続された場合は、磁気ディスク装置の電源投入時の起動電流や装置立ち上がり時の突入電流が大きく、これら起動電流等に対応することができる大容量に設計しなければならなかった。
【０００４】
更に従来システムは、バッテリの充電特性をワット数で指定しているため、入力電圧が変動した場合や負荷装置の電力が変動した場合は、充電電流も変化し、例えば充電電流が微少な場合は充電時間が冗長になりバッテリの回復が遅くなり、逆に充電電流が過大な場合は過充電になり、危険な状態になると言う不具合が有った。
【０００５】
更に従来システムは、例えばバッテリの消耗が多く、急速に充電しなければならない場合でも、指定されたワット数で充電を行うために充電時間が冗長になると言う不具合があった。
【０００６】
本発明の目的は、前述の従来技術による不具合を除去することであり、バッテリへの充電電流をバッテリの消耗度合いに応じて一定に保つことができるバッテリ充電方法及び該充電方法を実施するバックアップ電源装置を提供することである。
【０００７】
【課題を解決するための手段】
前記目的を達成するために本発明は、交流電圧を直流電圧に変換するＡＣ／ＤＣ変換部と、該ＡＣ／ＤＣ変換部から出力された直流電圧を所定値の電圧に変換し、負荷容量が変化する負荷装置に出力するＤＣ／ＤＣ変換部と、前記ＡＣ／ＤＣ変換部から電流を取り込んで充電を行うニッケル水素電池からなるバッテリとを備えるバックアップ電源装置のバッテリ充電方法であって、
前記ＡＣ／ＤＣ変換部の限界電流値と、バッテリに対する急速充電モード時のバッテリ充電電流値又は低速充電モード時のバッテリ充電電流値とを設定し、
前記ＤＣ／ＤＣ変換部の電流値を検出し、前記限界電流値からＤＣ／ＤＣ変換部からの電流値を減算したバッテリ充電可能な充電可能電流値と前記設定されたバッテリ充電電流値を比較し、
前記バッテリ充電可能な充電可能電流値又はバッテリ充電電流値のうちの低電流値に応じて半導体素子のスイッチング制御を行い、
前記ＡＣ／ＤＣ変換部の限界電流値は、前記負荷装置の最大容量に前記バッテリに対する低速充電モード時のバッテリ充電電流値を加算した値以上に設定して、急速充電モード時に前記急速充電モード時のバッテリ充電電流値と前記充電可能電流値を比較して前記急速充電モード時のバッテリ充電電流値の方が低い場合には前記急速充電モード時のバッテリ充電電流値によって、前記充電可能電流値の方が低い場合には前記充電可能電流値によって、また、低速充電モード時には前記低速充電モード時のバッテリ充電電流値によって、バッテリ充電を行うことを第１の特徴とする。
【０００８】
更に本発明は、交流電圧を直流電圧に変換するＡＣ／ＤＣ変換部と、該ＡＣ／ＤＣ変換部から出力された直流電圧を所定値の電圧に変換し、負荷容量が変化する負荷装置に出力するＤＣ／ＤＣ変換部と、前記ＡＣ／ＤＣ変換部から電流を取り込んで充電を行うニッケル水素電池からなるバッテリとを備えるバックアップ電源装置であって、
前記ＡＣ／ＤＣ変換部の限界電流値を設定する第１の設定回路と、
バッテリに対する急速充電モード時のバッテリ充電電流値又は低速充電モード時のバッテリ充電電流値を設定する第２の設定回路と、
前記ＤＣ／ＤＣ変換部からの電流値を検出する電流検出回路と、
前記限界電流値からＤＣ／ＤＣ変換部からの電流値を減算したバッテリ充電可能な充電可能電流値と前記設定されたバッテリ充電電流値を比較する比較回路と、
前記バッテリ充電可能な充電可能電流値又はバッテリ充電電流値のうちの低電流値に応じて半導体素子のスイッチング制御を行い、バッテリ充電を行うバッテリ充電回路とを備え、
前記ＡＣ／ＤＣ変換部の限界電流値は、前記負荷装置の最大容量に前記バッテリに対する低速充電モード時のバッテリ充電電流値を加算した値以上に設定され、急速充電モード時に前記急速充電モード時のバッテリ充電電流値と前記充電可能電流値を比較して前記急速充電モード時のバッテリ充電電流値の方が低い場合には前記急速充電モード時のバッテリ充電電流値によって、前記充電可能電流値の方が低い場合には前記充電可能電流値によって、また、低速充電モード時には前記低速充電モード時のバッテリ充電電流値によって、バッテリ充電を一定電流値によって行うことを第２の特徴とする。
【０００９】
【発明実施の形態】
以下、本発明の一実施形態によるバッテリ充電方法及びバックアップ電源装置を図面を参照して詳細に説明する。図１は本実施形態によるバッテリ充電方法を適用したバックアップ電源装置の主な回路構成を示す図である。
【００１０】
まず本実施形態によるバックアップ電源装置は、交流電源と負荷装置間に配置され、ニッケル水素電池をバッテリとして使用するものであって、該バッテリの放電量に伴い、バッテリの充電量が小さい場合は所定の大電流によって充電を行う急速充電モード（例えば、容量が３Ａｈのバッテリの場合、６Ａによる急速充電）と、バッテリの充電量が大きい場合は所定の小電流によって充電を行う低速充電モード（例えば、容量が３Ａｈのバッテリの場合、０．６Ａによる低速充電）とを持ち、図１に示す如く、従来と同等のＡＣ／ＤＣ変換部１０１とＤＣ／ＤＣ変換部１０２と、前記ＤＣ／ＤＣ変換部１０２の出力電流値を入力部にて電圧値として検出する電流検出部５と、該電流検出部５の両端から延びる線路間に挿入されるコンデンサ２１０と、該線路の一方の線路に設けられるダイオード２１１及びＭＯＳＦＥＴ２１３から成る並列回路と、該並列回路の出力及び前記線路の他方間に挿入されるダイオード２１２と、チョークコイル２１４と、バッテリ２０９と、該バッテリ２０９に供給される電流値を電圧値として検出する検出回部２０６とを備え、前記コンデンサ２１０／ダイオード２１２／ＭＯＳＦＥＴ２１３／チョークコイル２１４が降圧回路を構成し、前記ＭＯＳＦＥＴ２１３が後述する指令信号によってオン／オフ制御されることによってバッテリ２０９への充電が行われる様に構成されている。尚、本実施形態においてはニッケル水素電池をバッテリとして使用する例を説明するが、本発明はこれに限定されるものではない。
【００１１】
このＭＯＳＦＥＴ２１３をオン／オフする回路構成は、電流値を電圧値に変換して制御を行うものであって、前記ＡＣ／ＤＣ変換部１０１の限界電流値を電圧値ｂとして予め設定するための設定回路２２０と、前記電流検出部５及び設定回路２２０の両出力ａｂを入力として限界値ｂから検出値ａを減算する減算器２０１と、該減算器２０１の出力ｃと後述するスライスレベルｈを入力とし、掛け算を行う掛け算器２０２と、バッテリ２０９への充電すべき電流値を急速又は低速モードに応じた電圧値ｅとして設定するための充電電流値設定回路２０４と、該設定回路２０４から指定された電圧値ｅと前記掛け算器２０２の出力ｄとを比較して低レベルの値ｆを出力する比較器２０３と、該比較器２０３の出力ｆと前記バッテリ電流検出部２０６からの出力ｇを入力として減算することによりスライスレベルｈを出力する減算器２０８と、所定の三角波信号ｉを出力する三角波発生回路２０５と、前記スライスレベルｈと前記三角波発生回路２０５からの三角波信号ｉを入力とし、前記スライスレベルｈによって指定された幅のパルス信号ｊを出力することによってＭＯＳＦＥＴ２１３を駆動するパルス発生器２０７とを備える。尚、前記モードの切替は、バッテリ２０９の電圧値を図示しない回路によって検出し、充電量に応じて切り換えるものである。
【００１２】
＜急速充電モードの動作説明＞
この回路は、まず、ＡＣ／ＤＣ変換器１０１の能力である出力電流の限界値を電圧ｂとして設定回路２２０により設定すると共に、バッテリ２０９に充電すべき電流値を設定回路２０４により電圧ｅとして指定し、前記限界値の電圧ｂから実際にＤＣ／ＤＣ変換部１０２に供給している電流検出回路５からの電圧値ａを減算器２０１により減算し、現在、ＡＣ／ＤＣ変換部の能力からＤＣ／ＤＣ変換部に供給している電流値を引いた値、即ち、バッテリ充電可能な電流に相当する電圧ｃを出力する。ここで、例えば、ＡＣ／ＤＣ変換部の限界が１５Ａ（設定回路２２０の出力ｂが１５Ｖ）、電流検出回路５により検出した電流が５Ａ（出力ａが５Ｖ）、バッテリの消耗が多く急速充電モードで６Ａでの充電が充電電流値設定回路２０４により６Ｖとして設定され、減算器２０１は差分１０Ｖを出力した場合（掛け算器２０２の動作は後述）、比較器２０３には出力ｄの１０Ｖと設定回路２０４の出力ｅの６Ｖが入力され、比較器２０３から低い値である６Ｖが出力ｆとして出力される。
【００１３】
ここでバッテリ電流検出回路２０６の出力ｇが６Ｖ、即ち適正な場合は減算器２０８の出力は０となり、現在のスライスレベルｈが維持され、６Ａによるバッテリ充電が保持され、バッテリ電流検出回路２０６の出力ｇが８Ｖ、即ち過大な場合は減算器２０８によりｇ−ｆ（８Ｖ−６Ｖ）＝２Ｖがスライスレベルｈとして出力され、パルス発生器２０７からの三角波信号ｉのパルス幅を狭めた出力ｊによりＭＯＳＦＥＴ２１３を駆動することによって、バッテリ２０９へ供給する電流値を６Ａに下げる様に動作し、逆にバッテリ電流検出回路２０６の出力ｇが４Ｖ、即ち少ない場合は減算器２０８によりｇ−ｆ（４Ｖ−６Ｖ）＝−２Ｖがスライスレベルｈとして出力され、パルス発生器２０７からの三角波信号ｉのパルス幅を広めた出力ｊによりＭＯＳＦＥＴ２１３を駆動することによって、バッテリ２０９へ供給する電流値を６Ａに上げる様に動作する。
【００１４】
従って本実施形態によるバックアップ電源装置は、急速充電モードの場合、充電電流設定回路２０４によって指定した急速充電電流を６Ａに維持しながらバッテリ充電を行うことができる。また本実施形態は、負荷装置の必要とする電力が増大した場合、その増大を電流検出回路５により検出し、バッテリ充電に使用できる電流値を減算器２０１から出力ｃとして出力し、６Ｖを下回る場合は比較器２０３の出力が当該下回った電流値に相当する電圧値を出力するため、ＭＯＳＦＥＴ２１３による充電電流値を下げることによって、負荷が増大した場合であってもＡＣ／ＤＣ変換部の能力の範囲内且つ急速にバッテリ充電を行うことができる。逆に負荷が減収した場合においては比較器２０３から６Ｖが出力されるため、バッテリ２０９の過充電を防止することもできる。
【００１５】
尚、前述の掛け算器２０２は、前述した様に減算器２０１の出力ｃと後述するスライスレベルｈを入力とし、掛け算を行うことによって、入力電圧とバッテリ電圧の比率を示すパラメータであるデューティを検出して電流値の補正を行うものである。例えば、バッテリ電流検出器２０６で検出した電流値が２Ａ、ＡＣ／ＤＣ変換器１０１の出力電圧が４８Ｖ、バッテリ電圧が３０Ｖのとき、実際には、バッテリ２０９に対して［２Ａ×（出力電圧／バッテリ電圧）＝２Ａ×（４８Ｖ／３０Ｖ）］＝３．２Ａまで充電することができ、この補正を行うものである。
【００１６】
＜低速充電モードの動作説明＞
このモード時の回路は、前述の設定回路２２０による限界値の電圧ｂによる設定、設定回路２０４による充電すべき電流値の電圧ｅによる設定、充電電流値設定回路２０４による低速充電モードによる０．６Ｖの設定が成されているものとする。ここで、本回路は、前記限界値の電圧ｂから実際にＤＣ／ＤＣ変換部１０２に供給している電流検出回路５からの電圧値ａを減算器２０１により減算し、現在、ＡＣ／ＤＣ変換部の能力からＤＣ／ＤＣ変換部に供給している電流値を引いた値、即ち、バッテリ充電可能な電流に相当する電圧ｃを出力する。ここで、例えば、ＡＣ／ＤＣ変換部の限界が１５Ａ（設定回路２２０の出力ｂが１５Ｖ）、電流検出回路５により検出した電流が５Ａ（出力ａが５Ｖ）、バッテリの消耗が少ない低速充電モードで０．６Ａでの充電が充電電流値設定回路２０４により０．６Ｖとして設定されていた場合、減算器２０１は差分１０Ｖを出力し（掛け算器２０２の動作は除く）、比較器２０３には出力ｄの１０Ｖと設定回路２０４の出力ｅの０．６Ｖが入力され、比較器２０３から低い値である０．６Ｖが出力ｆとして出力される。
【００１７】
ここでバッテリ電流検出回路２０６の出力ｇが０．６Ｖ、即ち適正な場合は減算器２０８の出力は０となり、現在のスライスレベルｈが維持され、０．６Ａによるバッテリ充電が保持され、バッテリ電流検出回路２０６の出力ｇが８Ｖ、即ち過大な場合は減算器２０８によりｇ−ｆ（８Ｖ−０．６Ｖ）＝７．４Ｖがスライスレベルｈとして出力され、パルス発生器２０７からの三角波信号ｉのパルス幅を狭めた出力ｊによりＭＯＳＦＥＴ２１３を駆動することによって、バッテリ２０９へ供給する電流値を０．６Ｖに下げる様に動作し、逆にバッテリ電流検出回路２０６の出力ｇが０．２Ｖ、即ち少ない場合は減算器２０８によりｇ−ｆ（０．２−０．６Ｖ）＝−０．４Ｖがスライスレベルｈとして出力され、パルス発生器２０７からの三角波信号ｉのパルス幅を広めた出力ｊによりＭＯＳＦＥＴ２１３を駆動することによって、バッテリ２０９へ供給する電流値を０．６Ｖに上げる様に動作する。
【００１８】
従って本実施形態によるバックアップ電源装置は、低速充電モードの場合、充電電流設定回路２０４によって指定した低速充電電流を０．６Ａに維持しながらバッテリ充電を行うことができる。
【００１９】
この様に本実施形態によるバックアップ電源装置は、予めＡＣ／ＤＣ変換器の限界電流値の設定、急速又は低速充電モードによる充電電流の設定を行い、各モードにより指定された一定電流値によってバッテリ充電を行うことができ、このため急速充電モード時には短時間にバッテリ充電を行うことにより過充電を防止することができ、低速充電モード時には少ない充電電流によりバッテリ充電を行うことによりＡＣ／ＤＣ変換部に影響がない範囲でバッテリ充電を行うことができる。
【００２０】
更に本実施形態によるバックアップ電源装置は、予めＡＣ／ＤＣ変換器の限界電流値を設定すると共に負荷装置に供給しているＤＣ／ＤＣ変換部の供給電流を検出し、両者の差分の範囲内でバッテリ充電を行うため、ＡＣ／ＤＣ変換部の容量を必要最低限に抑えることができる。
【００２１】
具体的に説明すると、高速充電モードの場合、従来技術においてはＡＣ／ＤＣ変換部の負荷が通常５Ａで周期的に１３Ａ必要となるとき、ＡＣ／ＤＣ変換部は１３Ａに充電用電流値６Ａを加え、更にマージンを考慮した２０Ａ以上の大容量にしなければならなかったが、本実施形態においては、ＡＣ／ＤＣ変換部１の電流限界値を設定し、この限界値からＤＣ／ＤＣ変換部に供給されている検出電流値減算した値（出力ｃ）の範囲内で、モードにより設定された充電電流値により充電を行うため、即ち、従来の如く設定されたワット数に従った電流値を設定しないため、大容量のＡＣ／ＤＣ変換部を不必要とすることができる。
【００２２】
またＤＣ／ＤＣ変換部負荷が５Ａ→１３Ａ（２０ｓ間）→５Ａと変化するとき、バックアップ電源の取り込み電流は６Ａ→２Ａ（２０ｓ間）→６Ａとなるため、ＡＣ／ＤＣ変換部は１１Ａ→１５Ａ→１１Ａと従来に比べて低容量にすることができる。
【００２３】
尚、前記実施形態においては、電流値を一旦電圧値に変換してバッテリへの充電電流をモードに応じて一定値に保つ例を説明したが本発明は、これに限られるものではなく、電流値そのものを検出して制御する様に構成しても良い。
【００２４】
【発明の効果】
以上述べた如く本発明によれば、ＡＣ／ＤＣ変換部の限界電流値ｂとバッテリに対する急速充電モード又は低速充電モード時のバッテリ充電電流値ｅとを設定し、ＤＣ／ＤＣ変換器の電流値ａを検出し、前記限界電流値ｂからＤＣ／ＤＣ変換器の電流値ａを減算したバッテリ充電可能な充電可能電流値ｃと前記モードにより設定されたバッテリ充電電流値ｅを比較し、両電流値のうちの低電流値によってバッテリ充電を行うことによって、バッテリへの充電電流をバッテリの消耗度合いに応じて一定に保つことができると共にＡＣ／ＤＣ変換部の容量を小容量とすることができる。
【図面の簡単な説明】
【図１】本発明の一実施形態によるバックアップ電源装置の主な回路構成を示す図。
【図２】従来技術による電源システムを説明するための図。
【符号の説明】
１０１：ＡＣ／ＤＣ変換部、１０２：ＤＣ／ＤＣ変換部、２００：交流電源、３００：負荷装置、５：電流検出部、２０１：減算器、２０２：掛け算器、２０３：比較器、２０４：充電電流設定回路、２０５：三角波発生回路、２０７：パルス発生回路、２０８：減算器、２０９：バッテリ、２２０：ＡＣ／ＤＣ変換部の限界電流設定回路。[0001]
[Industrial application fields]
The present invention relates to a battery charging method for a battery for performing uninterruptible power in a power supply device, and a backup power supply device that implements the charging method, and in particular, charging a battery suitably without applying a load to an AC / DC converter. The present invention relates to a battery charging method that can be performed and a backup power supply apparatus that implements the charging method.
[0002]
[Prior art]
Generally, a peripheral device in a computer system is connected to a power supply device for securing a constant power supply and an uninterruptible device (UPS) for responding to a power failure. As shown in FIG. 2, the power supply system according to this prior art includes an uninterruptible device 500 for charging a battery using an electric power composed of an electric current Iin and a voltage Vin from an AC power source 200, and an alternating voltage from the uninterruptible device 500 as a direct current. The uninterruptible device 500 converts the input voltage Vin into a DC voltage by the AC / DC converter 1 and converts the voltage V ₁ into DC / AC. is intended to charge the electric current I ₂ to the battery 4 via the charging and discharging circuit 3 is supplied by the converter 2 from the back to the AC to the next stage of the power supply device 100, the power supply device 100, from the uninterruptible device 500 An AC voltage is converted into a direct current by the AC / DC converter 101, and a DC current of a predetermined voltage is further supplied to the load device 300 by the DC / DC converter 102. Discharge circuit 3 is configured wattage power specified from the output of the AC / DC converter unit 1 so as to charge the battery 4.
[0003]
[Problems to be solved by the invention]
In the power supply system configured in this way, the current value changes depending on the power required by the load device 300, and therefore the capacities of the AC / DC conversion unit and the DC / DC conversion unit are set according to the current required by the load device. There was a problem that it was necessary to design a large capacity. For example, when multiple magnetic disk units are connected to the load unit, the startup current when the magnetic disk unit is turned on and the inrush current when the unit starts up are large, and the capacity is designed to handle these startup currents. Had to do.
[0004]
Furthermore, since the conventional system specifies the battery charging characteristics in wattage, the charging current also changes when the input voltage changes or the load device power changes. For example, when the charging current is very small There is a problem that the charging time becomes redundant and the recovery of the battery is delayed, and conversely, when the charging current is excessive, the battery is overcharged, resulting in a dangerous state.
[0005]
Furthermore, the conventional system has a problem in that, for example, even when the battery is exhausted and the battery needs to be charged quickly, the charging time becomes redundant in order to perform charging with a specified wattage.
[0006]
SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned problems caused by the prior art, a battery charging method capable of keeping the charging current to the battery constant according to the degree of battery consumption, and a backup power supply for implementing the charging method. Is to provide a device.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides an AC / DC converter that converts an AC voltage into a DC voltage, and converts the DC voltage output from the AC / DC converter into a voltage having a predetermined value, so that the load capacity is reduced. A battery charging method for a backup power supply device comprising: a DC / DC conversion unit that outputs to a changing load device; and a battery that is a nickel hydride battery that performs charging by taking in current from the AC / DC conversion unit,
Setting a limit current value of the AC / DC converter and a battery charging current value in a fast charging mode or a battery charging current value in a slow charging mode for the battery;
The current value of the DC / DC conversion unit is detected, and the battery chargeable current value obtained by subtracting the current value from the DC / DC conversion unit from the limit current value is compared with the set battery charging current value. ,
The switching control of the semiconductor element is performed according to the low current value of the chargeable current value or the battery charging current value that can be charged by the battery,
The limit current value of the AC / DC converter is set to a value equal to or greater than the maximum capacity of the load device plus a battery charge current value in the low-speed charge mode for the battery. If the battery charge current value in the quick charge mode is lower by comparing the battery charge current value of the battery and the chargeable current value, the battery charge current value in the quick charge mode The first characteristic is that the battery is charged by the chargeable current value when the charge rate is lower, and by the battery charge current value in the slow charge mode in the slow charge mode.
[0008]
Furthermore, the present invention provides an AC / DC converter that converts an AC voltage into a DC voltage, and converts the DC voltage output from the AC / DC converter into a voltage having a predetermined value, which is output to a load device whose load capacity changes. A backup power supply device comprising: a DC / DC converter that performs charging; and a battery that includes a nickel metal hydride battery that performs charging by taking in current from the AC / DC converter,
A first setting circuit for setting a limit current value of the AC / DC converter;
A second setting circuit for setting a battery charging current value in a rapid charging mode or a battery charging current value in a low-speed charging mode for the battery;
A current detection circuit for detecting a current value from the DC / DC converter;
A comparison circuit that compares the set battery charge current value with a chargeable current value that can be charged by the battery by subtracting the current value from the DC / DC converter from the limit current value;
The have line switching control of the semiconductor device in accordance with the low current value of the battery chargeable chargeable current or battery charging current value, and a battery charging circuit that performs battery charge,
The limit current value of the AC / DC converter is set to a value equal to or greater than the maximum capacity of the load device plus the battery charge current value in the slow charge mode for the battery. When the battery charge current value and the chargeable current value are compared and the battery charge current value in the quick charge mode is lower, the chargeable current value is determined according to the battery charge current value in the quick charge mode. The second characteristic is that the battery is charged with a constant current value when the battery is low, according to the chargeable current value, and when in the low-speed charge mode, depending on the battery charge current value in the low-speed charge mode.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a battery charging method and a backup power supply according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a main circuit configuration of a backup power supply apparatus to which the battery charging method according to the present embodiment is applied.
[0010]
First, the backup power supply device according to the present embodiment is arranged between an AC power supply and a load device, and uses a nickel metal hydride battery as a battery. When the charge amount of the battery is small along with the discharge amount of the battery, the backup power supply device is predetermined. A fast charging mode in which charging is performed with a large current (for example, a rapid charging by 6A in the case of a battery with a capacity of 3 Ah) and a low-speed charging mode in which charging is performed with a predetermined small current when the battery is charged (for example, In the case of a battery with a capacity of 3 Ah, it has a low-speed charging at 0.6 A), and as shown in FIG. 1, an AC / DC converter 101 and a DC / DC converter 102 equivalent to the conventional one, and the DC / DC converter A current detection unit 5 that detects an output current value of 102 as a voltage value at an input unit; and a capacitor 2 that is inserted between lines extending from both ends of the current detection unit 5 0, a parallel circuit composed of a diode 211 and a MOSFET 213 provided on one of the lines, an output of the parallel circuit and a diode 212 inserted between the other of the lines, a choke coil 214, a battery 209, A detecting circuit 206 that detects a current value supplied to the battery 209 as a voltage value, and the capacitor 210 / diode 212 / MOSFET 213 / choke coil 214 constitutes a step-down circuit, and the MOSFET 213 receives a command signal described later. The battery 209 is configured to be charged by being controlled on / off. In this embodiment, an example in which a nickel metal hydride battery is used as a battery will be described, but the present invention is not limited to this.
[0011]
The circuit configuration for turning on / off the MOSFET 213 performs control by converting a current value into a voltage value, and is a setting for presetting the limit current value of the AC / DC converter 101 as the voltage value b. The circuit 220, the subtracter 201 for subtracting the detection value a from the limit value b with the outputs ab of the current detector 5 and the setting circuit 220 as inputs, the output c of the subtractor 201 and a slice level h described later are input. Designated by the setting circuit 204, a multiplier 202 for performing multiplication, a charging current value setting circuit 204 for setting a current value to be charged to the battery 209 as a voltage value e corresponding to the rapid or low speed mode, and A comparator 203 that compares the measured voltage value e with the output d of the multiplier 202 and outputs a low-level value f; and the output f of the comparator 203 and the battery current detector 2 6, the subtractor 208 that outputs the slice level h by subtracting the output g from the input, the triangular wave generation circuit 205 that outputs a predetermined triangular wave signal i, and the triangular wave from the slice level h and the triangular wave generation circuit 205. A pulse generator 207 for driving the MOSFET 213 by receiving a signal i and outputting a pulse signal j having a width specified by the slice level h. The mode switching is performed by detecting the voltage value of the battery 209 using a circuit (not shown) and switching according to the amount of charge.
[0012]
<Explanation of operation in quick charge mode>
In this circuit, first, the limit value of the output current, which is the capability of the AC / DC converter 101, is set as the voltage b by the setting circuit 220, and the current value to be charged in the battery 209 is specified as the voltage e by the setting circuit 204. Then, the voltage value a from the current detection circuit 5 that is actually supplied to the DC / DC converter 102 is subtracted from the limit value voltage b by the subtractor 201, and the current value of the AC / DC converter is determined to be DC. A value obtained by subtracting the current value supplied to the DC converter, that is, a voltage c corresponding to the current that can be charged by the battery is output. Here, for example, the limit of the AC / DC conversion unit is 15A (the output b of the setting circuit 220 is 15V), the current detected by the current detection circuit 5 is 5A (the output a is 5V), and the battery is consumed much and the quick charge mode When charging at 6 A is set as 6 V by the charging current value setting circuit 204 and the subtractor 201 outputs a difference of 10 V (the operation of the multiplier 202 will be described later), the comparator 203 outputs 10 V of the output d and the setting circuit. 6V of the output e of 204 is inputted, and 6V which is a low value is outputted from the comparator 203 as the output f.
[0013]
Here, when the output g of the battery current detection circuit 206 is 6V, that is, when appropriate, the output of the subtracter 208 is 0, the current slice level h is maintained, the battery charge by 6A is maintained, and the battery current detection circuit 206 When the output g is 8V, that is, excessive, g−f (8V−6V) = 2V is output as the slice level h by the subtracter 208, and the output j is obtained by narrowing the pulse width of the triangular wave signal i from the pulse generator 207. By driving the MOSFET 213, the current value supplied to the battery 209 is reduced to 6 A. Conversely, when the output g of the battery current detection circuit 206 is 4V, that is, when the output g is small, the subtractor 208 causes g−f (4V− 6V) = − 2V is output as the slice level h, and the output j is obtained by widening the pulse width of the triangular wave signal i from the pulse generator 207. By driving the MOSFET213 Ri operated as to increase the current supplied to the battery 209 to 6A.
[0014]
Therefore, in the quick charge mode, the backup power supply apparatus according to the present embodiment can charge the battery while maintaining the rapid charge current designated by the charge current setting circuit 204 at 6A. Further, in the present embodiment, when the power required by the load device increases, the increase is detected by the current detection circuit 5, and the current value that can be used for battery charging is output as the output c from the subtractor 201, which is below 6V. In this case, since the output of the comparator 203 outputs a voltage value corresponding to the current value that has fallen, the charging current value by the MOSFET 213 is reduced, so that the capability of the AC / DC converter can be improved even when the load increases. The battery can be charged within the range and rapidly. On the other hand, when the load decreases, 6 V is output from the comparator 203, so that overcharging of the battery 209 can be prevented.
[0015]
The multiplier 202 described above receives the output c of the subtractor 201 and a slice level h, which will be described later, as described above, and detects the duty, which is a parameter indicating the ratio between the input voltage and the battery voltage, by performing multiplication. Thus, the current value is corrected. For example, when the current value detected by the battery current detector 206 is 2 A, the output voltage of the AC / DC converter 101 is 48 V, and the battery voltage is 30 V, actually, [2 A × (output voltage / Battery voltage) = 2A × (48V / 30V)] = 3.2 A can be charged, and this correction is performed.
[0016]
<Description of operation in low-speed charging mode>
The circuit in this mode is set by the setting circuit 220 using the limit voltage b, the setting circuit 204 setting the current value to be charged by the voltage e, and the charging current value setting circuit 204 by the slow charge mode 0.6V. Is set. Here, the present circuit subtracts the voltage value a from the current detection circuit 5 that is actually supplied to the DC / DC conversion unit 102 from the voltage b of the limit value by the subtractor 201, and currently performs AC / DC conversion. A value c obtained by subtracting the current value supplied to the DC / DC conversion unit from the capacity of the unit, that is, a voltage c corresponding to the battery chargeable current is output. Here, for example, the limit of the AC / DC conversion unit is 15 A (the output b of the setting circuit 220 is 15 V), the current detected by the current detection circuit 5 is 5 A (the output a is 5 V), and the low-speed charging mode with less battery consumption When charging at 0.6 A is set as 0.6 V by the charging current value setting circuit 204, the subtractor 201 outputs a difference of 10 V (except for the operation of the multiplier 202) and outputs to the comparator 203. 10V of d and 0.6V of the output e of the setting circuit 204 are inputted, and a low value of 0.6V is outputted from the comparator 203 as the output f.
[0017]
Here, if the output g of the battery current detection circuit 206 is 0.6 V, that is, if appropriate, the output of the subtracter 208 is 0, the current slice level h is maintained, the battery charge by 0.6 A is maintained, the battery current When the output g of the detection circuit 206 is 8V, that is, it is excessive, g−f (8V−0.6V) = 7.4V is output as the slice level h by the subtracter 208, and the triangular wave signal i from the pulse generator 207 is output. By driving the MOSFET 213 with the output j with a narrow pulse width, the current value supplied to the battery 209 is reduced to 0.6 V, and conversely, the output g of the battery current detection circuit 206 is 0.2 V, that is, small. In this case, g−f (0.2−0.6 V) = − 0.4 V is output as the slice level h by the subtracter 208, and the triangle from the pulse generator 207 is output. By driving the MOSFET213 by the output j of spread the pulse width of the signal i, operated as to increase the current supplied to the battery 209 to 0.6V.
[0018]
Therefore, the backup power supply device according to the present embodiment can charge the battery while maintaining the low speed charging current designated by the charging current setting circuit 204 at 0.6 A in the low speed charging mode.
[0019]
As described above, the backup power supply apparatus according to the present embodiment sets the limit current value of the AC / DC converter in advance, sets the charging current in the rapid or low-speed charging mode, and charges the battery with the constant current value designated by each mode. Therefore, overcharge can be prevented by charging the battery in a short time in the quick charge mode, and the AC / DC converter can be charged by charging the battery with a small charge current in the low speed charge mode. Battery charging can be performed within a range where there is no influence.
[0020]
Furthermore, the backup power supply device according to the present embodiment sets the limit current value of the AC / DC converter in advance and detects the supply current of the DC / DC conversion unit supplied to the load device, and within the range of the difference between the two. Since the battery is charged, the capacity of the AC / DC converter can be minimized.
[0021]
Specifically, in the fast charge mode, when the load of the AC / DC converter is normally 5A and 13A is required periodically in the conventional technology, the AC / DC converter supplies the charging current value 6A to 13A. In addition, the capacity has to be increased to 20 A or more in consideration of the margin, but in the present embodiment, the current limit value of the AC / DC conversion unit 1 is set, and from this limit value to the DC / DC conversion unit. In order to perform charging with the charging current value set by the mode within the range of the value obtained by subtracting the supplied detection current value (output c), that is, the current value according to the wattage set as in the prior art is set. Therefore, a large-capacity AC / DC converter can be made unnecessary.
[0022]
When the load of the DC / DC converter changes from 5A → 13A (between 20s) → 5A, since the backup power supply current is 6A → 2A (between 20s) → 6A, the AC / DC converter is 11A → 15A. → 11A, which is a lower capacity than the conventional one.
[0023]
In the embodiment, the example in which the current value is once converted into the voltage value and the charging current to the battery is kept constant according to the mode has been described, but the present invention is not limited to this. You may comprise so that a value itself may be detected and controlled.
[0024]
【The invention's effect】
As described above, according to the present invention, the limit current value b of the AC / DC converter and the battery charge current value e in the quick charge mode or the slow charge mode for the battery are set, and the current value of the DC / DC converter is set. a is detected, the chargeable current value c that can be charged by subtracting the current value a of the DC / DC converter from the limit current value b is compared with the battery charge current value e set by the mode, and both currents are compared. By charging the battery with a low current value among the values, the charging current to the battery can be kept constant according to the degree of consumption of the battery, and the capacity of the AC / DC converter can be made small. .
[Brief description of the drawings]
FIG. 1 is a diagram showing a main circuit configuration of a backup power supply apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram for explaining a power supply system according to a conventional technique.
[Explanation of symbols]
101: AC / DC converter, 102: DC / DC converter, 200: AC power supply, 300: load device, 5: current detector, 201: subtractor, 202: multiplier, 203: comparator, 204: charging Current setting circuit, 205: triangular wave generation circuit, 207: pulse generation circuit, 208: subtractor, 209: battery, 220: limit current setting circuit of AC / DC converter.

Claims

An AC / DC converter for converting an alternating voltage into a direct voltage;
A DC / DC converter that converts the DC voltage output from the AC / DC converter into a voltage of a predetermined value and outputs the voltage to a load device whose load capacity changes;
A battery charging method for a backup power supply apparatus comprising a battery made of a nickel metal hydride battery that takes in current from the AC / DC converter and performs charging,
Setting a limit current value of the AC / DC converter and a battery charging current value in a fast charging mode or a battery charging current value in a slow charging mode for the battery;
The current value of the DC / DC conversion unit is detected, and the battery chargeable current value obtained by subtracting the current value from the DC / DC conversion unit from the limit current value is compared with the set battery charging current value. ,
The switching control of the semiconductor element is performed according to the low current value of the chargeable current value or the battery charging current value that can be charged by the battery,
The limit current value of the AC / DC converter is set to a value equal to or greater than the maximum capacity of the load device plus a battery charge current value in the low-speed charge mode for the battery. If the battery charge current value in the quick charge mode is lower by comparing the battery charge current value of the battery and the chargeable current value, the battery charge current value in the quick charge mode A battery charging method comprising: charging the battery according to the chargeable current value when the charge rate is lower, and according to the battery charge current value during the low-speed charge mode in the low-speed charge mode.

An AC / DC converter for converting an alternating voltage into a direct voltage;
A DC / DC converter that converts the DC voltage output from the AC / DC converter into a voltage of a predetermined value and outputs the voltage to a load device whose load capacity changes;
A backup power supply device comprising a battery made of a nickel metal hydride battery that takes in current from the AC / DC converter and performs charging,
A first setting circuit for setting a limit current value of the AC / DC converter;
A second setting circuit for setting a battery charging current value in a rapid charging mode or a battery charging current value in a low-speed charging mode for the battery;
A current detection circuit for detecting a current value from the DC / DC converter;
A comparison circuit that compares the set battery charge current value with a chargeable current value that can be charged by the battery by subtracting the current value from the DC / DC converter from the limit current value;
The have line switching control of the semiconductor device in accordance with the low current value of the battery chargeable chargeable current or battery charging current value, and a battery charging circuit that performs battery charge,
The limit current value of the AC / DC converter is set to a value equal to or greater than the maximum capacity of the load device plus the battery charge current value in the slow charge mode for the battery. When the battery charge current value and the chargeable current value are compared and the battery charge current value in the quick charge mode is lower, the chargeable current value is determined according to the battery charge current value in the quick charge mode. The battery pack is charged with a constant current value according to the chargeable current value when the battery voltage is low, and according to the battery charge current value during the low-speed charge mode in the low-speed charge mode.