JP3623766B2

JP3623766B2 - AC power supply

Info

Publication number: JP3623766B2
Application number: JP2001304287A
Authority: JP
Inventors: 実柳沢; 芳明奥井
Original assignee: Sanyo Denki Co Ltd
Current assignee: Sanyo Denki Co Ltd
Priority date: 2001-09-28
Filing date: 2001-09-28
Publication date: 2005-02-23
Anticipated expiration: 2021-09-28
Also published as: JP2003111426A

Description

【０００１】
【発明の属する技術分野】
本発明は、負荷の変動に対して比較的に大きな遅れを持って応答する特性を有する交流電源に関するものである。
【０００２】
【従来の技術】
従来は、エンジン発電機（以下ＥＧと略称する）などのような負荷の変動に対して比較的に大きな遅れを持って応答する交流電源を用いて良質な交流電源装置にするため、発電機と負荷との間に整流器とインバータとからなる電力変換装置を直列に挿入し、これら整流器とインバータとの接続点に蓄電池の一端を接続して、交流を常時整流して充電し、充電した直流をインバータで辛うじて良質な交流として負荷に供給していた。蓄電池は蓄積電力のある動作範囲においてほぼ一定の電圧を示し、発電機の応答の遅れ（数百ｍｓ）には蓄積電力を供給してカバーしていた。こうした公知例の一つに特開昭５４−５３２３６号公報に示された「無停電電源装置の運転方法」がある。
【０００３】
【発明が解決しようとする課題】
従来は、エンジン発電機の発電容量を大きくして、負荷の変動に対処していた。しかしこれでは、大型の発電機を用意しなければならないと云う課題があった。しかもこの方法では整流器とインバータと２つの電力装置を経由して常時電力を供給するので、総合した電力効率は８５％程度となっている。
【０００４】
本発明の目的は、整流器を必要とせず、しかも発電機の発電容量を必要以上に大きくする必要のない交流電源装置を提供することにある。
【０００５】
本発明の他の目的は、従来よりも電力変換効率の良い交流電源装置を提供することにある。
【０００６】
【課題を解決するための手段】
本発明の交流電源装置は、負荷の変動に対して比較的に大きな遅れを持って応答する特性を有する交流電源と、蓄電池と、電力変換器と、制御指令発生手段と、蓄積電力制御指令発生回路とから構成されている。
【０００７】
電力変換器は、交流電源と負荷とを接続する給電線路及び蓄電池に接続され、交流電源の出力の少なくとも一部を直流電力に順変換して蓄電池を充電する順変換動作と、負荷に供給すべき電力が不足しているときには蓄電池の直流電力を交流電力に逆変換して負荷に不足電力分を供給する逆変換動作と、その他のときに給電線路の無効電力を調整して交流電源の出力電流を正弦波に近付けるアクティブフィルタ動作とを行うように構成されている。
【０００８】
また制御指令発生手段は、負荷に流れる負荷電流及び交流電源の出力電圧と同期した正弦波電圧に基づいて負荷電流の変動分を含む負荷電流変動分含有信号を発生する負荷電流変動分含有信号発生手段、並びに電力変換器と蓄電池とを接続する直流線路の直流電圧及び交流電源の出力電圧と同期した正弦波電圧に基づいて直流電圧の変動分を含む直流電圧変動分含有正弦波信号を発生する正弦波信号発生手段を含んで、負荷電流変動分含有信号発生手段の出力と正弦波信号発生手段の出力と前記電力変換器を流れる交流電流とに基づいて、電力変換器に逆変換動作を行わせるための電流制御指令及び電力変換器に順変換動作及びアクティブフィルタ動作を行わせるための電流制御指令を電力変換器に出力するように構成される。更に、負荷電流変動分含有信号発生手段及び正弦波信号発生手段のいずれか一方に遅延回路が設けられている。遅延回路の遅延時間または遅延特性は、交流電源の負荷変動に対応する応答速度の遅れに対応するように定められている。したがって対象となる交流電源ごとに遅延回路の遅延時間または遅延特性を定めることになる。
【０００９】
また蓄積電力制御指令発生回路は、直流線路の電圧と電流とを検出して蓄電池の蓄積電力を監視し、蓄電池の充電と放電とをいつでも実行できるように蓄電池の蓄積電力を予め定めた基準蓄積電力範囲内に制御するための蓄積電力制御指令を発生し、正弦波信号発生手段に出力する。
【００１０】
本発明においては、正弦波信号発生手段は、蓄積電力制御指令に基づいて蓄電池の蓄積電力を基準蓄積電力範囲内に維持しながら、交流電源の応答特性の遅れを補償するのに必要な蓄電池の充放電を実行するための指令を含む正弦波信号を出力する。負荷電流変動分含有信号発生手段は、負荷電流の変動分を含む負荷電流変動分含有信号を出力する。そして制御指令発生手段は、この２つの出力信号と電力変換器を流れる交流電流とを比較して、電流制御指令を電力変換器に出力する。電力変換器では、順変換動作と逆変換動作とアクティブフィルタ動作とが電流制御指令に基づいて行われる。
【００１１】
本発明は、交流電源の応答特性の遅れに応じた遅れを電流制御指令に含ませることにより、交流電源の負担を軽減し、その遅れにより生じる電力の過不足を蓄電池を充放電することにより補う。例えば、負荷が急に大きくなる方向に変動した場合には、交流電源に応答特性の遅れがあれば、電力不足が生じることになる。そこでこの場合にには蓄電池の蓄積電力を電力変換手段で交流に変換して負荷に供給することによりこの電力不足を補う。また逆に、負荷が急に小さくなった場合には、過発電となるが、このときには電力変換手段が交流発電機の出力を直流に変換して蓄電池を充電して、過発電分の電力を吸収する。このような動作を可能にするために、本発明では、蓄積電力指令発生回路が蓄電池の蓄積電力を基準蓄積電力範囲内に維持するための蓄積電力制御指令を出力している。その結果、本発明の交流電源装置を用いると、負荷電流の変動があっても、応答特性の遅れのあるエンジン発電機等の交流発電機を用いて負荷に必要な電力を供給することができる。
【００１２】
更に本発明の他の交流電源装置は、負荷の変動に対して比較的に大きな遅れを持って応答する特性を有する交流電源と、蓄電池と、電力変換器と、他の制御指令発生手段と、蓄積電力制御指令発生回路とから構成されている。
【００１３】
電力変換器は、交流電源と負荷とを接続する給電線路及び蓄電池に接続され、交流電源の出力の少なくとも一部を直流電力に順変換して蓄電池を充電する順変換動作と、負荷に供給すべき電力が不足しているときには蓄電池の直流電力を交流電力に逆変換して負荷に不足電力分を供給する逆変換動作と、その他のときに給電線路の無効電力を調整して交流電源の出力電流を正弦波に近付けるアクティブフィルタ動作とを行う。
【００１４】
他の制御指令発生手段は、負荷に流れる負荷電流を検出する負荷電流検出手段と、電力変換器と蓄電池とを接続する直流線路の直流電圧及び交流電源の出力電圧と同期した正弦波電圧に基づいて直流電圧の変動分を含む直流電圧変動分含有正弦波信号を発生する正弦波信号発生手段を含んで、負荷電流検出手段の出力と正弦波信号発生手段の出力と前記電力変換器を流れる交流電流とに基づいて、電力変換器に逆変換動作を行わせるための電流制御指令及び電力変換器に順変換動作及びアクティブフィルタ動作を行わせるための電流制御指令を電力変換器に出力するように構成される。更に正弦波信号発生手段には遅延回路が設けられ、交流電源の応答特性の遅れに応じた遅れを電流制御指令に含ませる。
【００１５】
蓄積電力制御指令発生回路は、蓄電池の蓄積電力を監視し、蓄電池の充電と放電とをいつでも実行できるように蓄電池の蓄積電力を予め定めた基準蓄積電力範囲内に制御するための蓄積電力制御指令を発生する。
【００１６】
本発明の他の制御指令発生手段の正弦波信号発生手段は、蓄積電力制御指令に基づいて蓄電池の蓄積電力を基準蓄積電力範囲内に維持しながら、交流電源の応答特性の遅れを補償するのに必要な蓄電池の充放電を実行するための指令を含む正弦波信号を発生しその出力と、負荷電流検出手段の出力と、この２つの出力信号は電力変換器を流れる交流電流と比較されて、電流制御指令が電力変換器に出力される。電力変換器は、順変換動作と逆変換動作とアクティブフィルタ動作とが電流制御指令に基づいて行われ、負荷電流の変動にも順応して発電機電流が正弦波になるように制御することができる。
【００１７】
更に本発明において、正弦波信号発生手段は、蓄電池を定電流で充放電するのに必要な定電流指令を発生する直流電流制御回路を更に含んでおり、定電流指令が入力指令の１つとして正弦波発生回路に入力され、正弦波発生回路は定電流指令が入力されているときには、蓄電池を予め定めた最大電流値以下の定電流で充電するように正弦波信号の振幅を変化させるように構成されている。これによって蓄電池の充放電に際し、過大電流による電極の損傷や電池性能の劣化を防ぐことができる。
【００１８】
更に本発明においては、電力の蓄積を行う蓄電池を、電力の蓄積状態が電圧のみで監視できるコンデンサで置き換えて構成することができる。本発明におけるコンデンサには大容量の電気二重層等が適している。コンデンサを用いる構成では、蓄積電力制御指令発生回路の入力には直流線路の直流電圧のみで蓄積電力の監視が可能で、コンデンサ６への充放電電流の入力は必要なく、その分蓄積電力制御指令発生回路は部品点数が少なくなり、安価になる。
【００１９】
本発明における蓄積電力制御指令発生回路は、蓄電池の蓄積電力を監視し、蓄電池の充電と放電とをいつでも実行できるように蓄電池の蓄積電力を予め定めた基準蓄積電力範囲内に制御するための蓄積電力制御指令を発生する。換言すれば、常時充電完了状態に充電する通常の充電回路と異なり、本発明における充電状態は、負荷で不足した電流を供給したり、逆に負荷で過剰となった電流を吸収できるように、常に充電状態を中間充電の状態に保つ。即ち予め定めた基準蓄積電力範囲内に制御するように回路は構成されている。
【００２０】
【発明の実施の形態】
以下、図面を参照して本発明の実施の形態の一例を詳細に説明する。
【００２１】
図１は本発明の交流電源装置の実施の形態の一例の構成を示すブロック回路図である。図１に示した交流電源装置は、負荷３の変動に対して比較的に大きな遅れを持って応答する特性を有する交流電源１と、蓄電池５と、電力変換器７と、制御指令発生手段９と、蓄積電力制御指令発生回路１１とから構成されている。
【００２２】
この例の交流電源１は、エンジン発電機である。また負荷３は、モータやヒータなどの一般負荷である。電力変換器７は電力変換手段１３とＰＷＭ回路１５とから構成され、電力変換手段１３には複数の制御半導体素子が含まれている。電力変換手段１３は、交流電源１の出力の少なくとも一部を直流電力に順変換して直流線路４を通して蓄電池５を充電する順変換動作と、負荷３に供給すべき電力が不足しているときには蓄電池５の直流電力を交流電力に逆変換して負荷３に不足電力分を供給する逆変換動作と、その他のときに給電線路２の無効電力を調整して交流電源１の出力電流ｉ_ＣＳを正弦波に近付けるアクティブフィルタ動作とを、後述の制御指令発生手段９の出力に応じて行うように構成されている。このような電力変換手段１３の構成は公知であるため詳細は省略する。ＰＷＭ回路１５は、制御指令発生手段９の出力に応じて電力変換手段１３の複数の制御半導体素子をＰＷＭ制御する。
【００２３】
制御指令発生手段９は、負荷電流変動分含有信号発生手段２１と正弦波信号発生手段２３とを含んでいる。この負荷電流変動分含有信号発生手段２１は、負荷３に流れる負荷電流ｉ_Ｌを負荷電流検出手段１７により検出し、検出した負荷電流ｉ_Ｌを整流器Ｄとローパスフィルタ（以下ＬＰＦと略記）３１とからなる平均値化回路２５で遅れ時間を含んで平均値化して直流電圧信号に変換し、この直流電圧信号と交流電源１の出力電圧Ｖ_ＣＳとを乗算器Ｍで乗算した信号に対し負荷電流ｉ_Ｌとの差信号を減算器Ｓで求め、負荷電流変動分含有信号として出力するように構成されている。また正弦波信号発生手段２３は、直流線路４の直流電圧Ｖ_ＤＣと予め定めた基準電圧との差電圧を示す直流電圧制御指令を出力する直流電圧制御回路２７と、入力指令及び交流電源１の出力電圧Ｖ_ＣＳに基づいて交流電源１の出力電圧Ｖ_ＣＳに位相が同期し且つ入力指令に応じて振幅が変化する正弦波信号を出力する正弦波発生回路２９とを備えている。そして入力指令としては、直流電圧制御回路２７から出力される直流電圧制御指令及び蓄積電力制御指令発生回路１１から出力される蓄積電力制御指令が含まれる。又この正弦波発生回路２９は、蓄積電力制御指令に基づいて蓄電池５の蓄積電力を基準蓄積電力範囲内に維持しながら、直流電圧制御指令に基づいて交流電源１の応答特性の遅れを補償するのに必要な蓄電池５の充放電を実行するための指令を振幅の変化として含む正弦波信号を出力するように構成されている。上記の負荷電流変動分含有信号発生手段２１の出力と正弦波信号発生手段２３の出力とを加算器Ａにより加算し、その出力に対し、電力変換器７を流れる交流電流ｉ_ＩＮＶを電流検出器１８により検出しその出力で減算し、電力変換器７に逆変換動作を行わせるための電流制御指令及び電力変換器７に順変換動作及びアクティブフィルタ動作を行わせるための電流制御指令を電力変換器７のＰＷＭ回路１５に出力するように構成されている。
【００２４】
蓄積電力制御指令発生回路１１は、蓄電池５の蓄積電力を監視し、蓄電池５の充電と放電とをいつでも実行できるように蓄電池５の蓄積電力を予め定めた基準蓄積電力範囲内に制御するための蓄積電力制御指令を発生する。そのため直流線路４の直流電圧Ｖ_ＤＣと、充放電電流ｉ_ＤＣを電流検出器１９により検出しその出力とを監視する。換言すれば、常時充電完了状態に充電する通常の充電回路と異なり、本発明においては、負荷３で不足した電流を供給したり、逆に負荷３で過剰となった電流を吸収できるように、常に蓄電池５の充電状態を中間充電の状態、即ち予め定めた基準蓄積電力範囲内に制御するように構成されている。
【００２５】
本発明においては、負荷電流変動分含有信号発生手段２１及び正弦波信号発生手段２３のいずれか一方に遅延回路が設けられ、交流電源１の応答特性の遅れに応じた遅れを電流制御指令及び電圧制御指令に含ませる構成であるが、図１においては、負荷電流変動分含有信号発生手段２１の中にＬＰＦ３１が含まれ、このＬＰＦ３１が遅延回路の役目を果たしている。
【００２６】
また、図１の負荷電流変動分含有信号発生手段２１は、平均値化回路２５を用いて構成されているが、平均値化回路２５の代わりに実効値回路を用いても負荷電流変動分含有信号発生手段を構成できる。それは実効値回路自体が遅れ要素を有し、ほぼ同様な効果が得られるからである。
【００２７】
図１の動作を電流波形図で説明する。図２は本発明の交流電源装置の実施形態の一例における定常運転時の各部の波形を示す波形図である。
【００２８】
図２において負荷３は整流器で、交流電源１の出力電圧Ｖ_ＣＳがある電圧レベルに達すると負荷電流ｉ_Ｌが流れ出す非直線負荷である。負荷電流ｉ_Ｌのピーク値は交流電源１の出力電流ｉ_ＣＳのピーク値以上となり、その不足分は蓄電池側より供給される。また、交流電源１の出力電圧Ｖ_ＣＳがあるレベルに達するまでの交流電源１の出力電流ｉ_ＣＳは負荷に流れず、過剰分として蓄電池側で吸収される。この電力変換器７を流れる交流電流ｉ_ＩＮＶは、ｉ_ＩＮＶ＝ｉ_ＣＳ−ｉ_Ｌであり、交流電源１の出力電流ｉ_ＣＳが正弦波になるように電力変換器７が制御指令発生手段９によって制御されるから、図のような電流波形ｉ_ＩＮＶになる。図２（Ａ）においては、この不足分と過剰分との電流が丁度打消し合った時のもので、全体として蓄電池５に電流が流れない蓄電池電流ゼロの場合であり、電流波形ｉ_ＩＮＶの基線上に蓄電池電流を示している点線が見られる。図２（Ｂ）はこの不足分と過剰分との電流が打消し合わない時のもので、図２（Ｂ）上図は全体として蓄電池５に電流が流れ込み、蓄電池５が充電されている場合である。上図の点線はその充電電流を示している。同（Ｂ）下図は全体として蓄電池５から電流が流れ出し、蓄電池５が放電している場合で、下図の点線は放電電流を示している。
【００２９】
図３は本発明の交流電源装置の実施形態の一例における負荷投入開放時の各部の波形を示す波形図である。図３において負荷３は図２と同様に整流器であり、電圧に対して非直線な負荷であり、蓄電池５は蓄電池電流ゼロの場合である。図３（Ａ）は負荷投入時の各部の波形で、投入時、エンジン発電機などの交流電源１はエンジンの回転が不十分のため、出力電圧Ｖ_ＣＳも出力電流ｉ_ＣＳも不十分で、その間の電力は蓄電池側から全て補給される。そのため、電流波形ｉ_ＩＮＶは負荷電流ｉ_Ｌとほぼ同じ波形となっている。エンジンの回転が時間と共に徐々に正規の回転に近づくにつれ、出力電圧Ｖ_ＣＳも出力電流ｉ_ＣＳも正規の出力となり、電流波形ｉ_ＩＮＶは図２（Ａ）の電流波形ｉ_ＩＮＶと同じ波形になる。図３（Ｂ）は負荷開放時の各部の波形で、負荷開放時に負荷電流ｉ_Ｌ＝０、従ってその瞬間から、ｉ_ＩＮＶ＝ｉ_ＣＳとなり、それが図に現れている。当然、負荷開放時には同時に発電機のエンジンは減速し停止し、出力電流ｉ_ＣＳは図のような減衰波形になる。
【００３０】
今の図２及び図３の説明では、負荷が出力電圧Ｖ_ＣＳに対して非線形な整流器について述べたが、出力電流ｉ_ＣＳに対して非線形な可飽和リアクタンスを負荷とした場合でも、或いは電圧や電流に対して線形な負荷で電流波形が電圧波形に対して遅れたり進んだりする負荷に対する場合でも同様に動作して、交流電源１の出力電流ｉ_ＣＳを出力電圧Ｖ_ＣＳと同相な正弦波になるように電力変換器７が制御指令発生手段９によって制御される。その理由は、正弦波発生回路２９が出力電圧Ｖ_ＣＳと同期する正弦波信号を電力変換器７に送り、電力変換器７のＰＷＭ回路１５が電力変換手段１３を制御するからである。
【００３１】
また、図２及び図３の上述の動作波形は、図１の交流電源装置について説明をしたが、後述の図４以降の本発明の交流電源装置についても同様であり、ここでは図１の交流電源装置を代表例として説明した。
【００３２】
図４は本発明の交流電源装置の実施の形態の他の一例の構成を示すブロック回路図である。本発明の交流電源装置は図４において図１と同一符号のブロックは同一機能を有するブロックであることを示す。図５以降においても同様である。
【００３３】
図４において本発明の他の交流電源装置は、負荷３の変動に対して比較的に大きな遅れを持って応答する特性を有する交流電源１と、蓄電池５と、電力変換器７と、制御指令発生手段１０９と、蓄積電力制御指令発生回路１１とから構成されている。
【００３４】
電力変換器７は電力変換手段１３とＰＷＭ回路１５とから構成され、電力変換手段１３には複数の制御半導体素子が含まれている。そして交流電源１と負荷３とを接続する給電線路２及び蓄電池５に接続され、交流電源１の出力の少なくとも一部を直流電力に順変換して蓄電池５を充電する順変換動作と、負荷３に供給すべき電力が不足しているときには蓄電池５の直流電力を交流電力に逆変換して負荷３に不足電力分を供給する逆変換動作と、その他のときに給電線路２の無効電力を調整して交流電源１の出力電流ｉ_ＣＳを正弦波に近付けるアクティブフィルタ動作とを行う。ＰＷＭ回路１５は電力変換手段１３の複数の制御半導体素子をＰＷＭ制御するためのＰＷＭ制御信号を生成する。
【００３５】
制御指令発生手段１０９は、負荷３に流れる負荷電流ｉ_Ｌを検出する負荷電流検出手段１７と、電力変換器７と蓄電池５とを接続する直流線路４の直流電圧Ｖ_ＤＣ及び交流電源の出力電圧Ｖ_ＣＳと同期した正弦波電圧に基づいて直流電圧の変動分を含む直流電圧変動分含有正弦波信号を発生する正弦波信号発生手段１２３と、電力変換器を流れる交流電流ｉ_ＩＮＶを検出する交流電流検出手段１８とを含んでいる。この正弦波信号発生手段１２３は、直流線路４の直流電圧Ｖ_ＤＣと予め定めた基準電圧との差電圧を示す直流電圧制御指令を出力する直流電圧制御回路２７と、入力指令及び交流電源１の出力電圧Ｖ_ＣＳに基づいて交流電源１の出力電圧Ｖ_ＣＳに位相が同期し且つ入力指令に応じて振幅が変化する正弦波信号を出力する正弦波発生回路２９とを備えている。そして入力指令として、直流電圧制御指令及び蓄積電力制御指令が含まれる。その正弦波発生回路２９は、蓄積電力制御指令に基づいて蓄電池５の蓄積電力を基準蓄積電力範囲内に維持しながら、直流電圧制御指令に基づいて交流電源１の応答特性の遅れを補償するのに必要な蓄電池５の充放電を実行するための指令を振幅の変化として含む正弦波信号を出力するように構成される。更に、遅延回路３１を構成するＬＰＦが直流電圧制御回路２７と正弦波発生回路２９との間に配置され、これによって交流電源１の応答特性の遅れに応じた遅れを電流制御指令及び電圧制御指令に含ませる。この正弦波信号発生手段１２３の出力と負荷電流検出手段１７の出力との差信号に対し、電力変換器７を流れる交流電流ｉ_ＩＮＶとの差信号が制御指令発生手段１０９の出力として電力変換器７のＰＷＭ回路１５の入力信号として用いられる。ＰＷＭ回路１５の出力は電力変換手段１３に加えられるように構成されている。電力変換器７は、逆変換動作と順変換動作とアクティブフィルタ動作とが電流制御指令に基づいて行われ、負荷電流ｉ_Ｌの変動にも順応して発電機電流ｉ_ＣＳが正弦波になるように制御することができる。
【００３６】
蓄積電力制御指令発生回路１１は、蓄電池５の蓄積電力を監視し、蓄電池５の充電と放電とをいつでも実行できるように蓄電池５の蓄積電力を予め定めた基準蓄積電力範囲内に制御するための蓄積電力制御指令を発生する。
【００３７】
図１及び図４に示したように、この本発明の構成は、構成自体が新規である。従来は交流電源１と負荷３との間に整流器とインバータとが直列に挿入されて構成されていた。従って、交流を常時直流に変換し、更にその直流を交流に常時再変換していた。この電力変換効率は夫々ほぼ９０％程度であり、２つ直列での総合効率は８１％程度に悪くなっていた。色々の工夫を加えても２０ＫＶＡ規模のエンジン発電機電源で８５％であった。それに対し、本発明においては上述したように、交流電源１と負荷３とは給電線路２によって直結されており、常時変換効率の悪さが影響しない構成である。そしてその給電線路２から分岐してインバータ型の電力変換器７が接続され、その電力変換器７の先に直流線路４を介して蓄電池５が接続されて、負荷電流ｉ_Ｌの過不足分のみを蓄電池５の充放電電流ｉ_ＤＣで補う構成であるため、電力変換効率が２０ＫＶＡ規模のエンジン発電機電源で９７％が得られている。このように構成が新規であるばかりでなく、この新規な構成が電力変換の高効率をもたらしている。従って、高効率の故に電源装置の運転費用が少なくて済む。
【００３８】
また、本発明によれば、負荷変動に対し応答速度の遅いエンジン発電機などの交流電源を用いても、発電容量に余裕を持たせる必要が無く、その分エンジン発電機を含めた交流電源装置の価格を低下させ、大きさを小型に出来る。更に電源と負荷とを直結する構成により、従来の高価な整流器が不必要となり、またその整流器の制御回路も不必要となり、経済的にも装置サイズの点でも一層大きな効果をもたらしている。
【００３９】
これら効果をもたらす本発明の鍵となる回路は蓄積電力制御指令発生回路１１である。蓄積電力制御指令発生回路１１は上述したように、負荷３で不足した電流を供給したり、逆に負荷３で過剰となった電流を吸収できるように、常に蓄電池５の充電状態を中間充電の状態、即ち予め定めた基準蓄積電力範囲内に制御するように構成されている。この蓄積電力制御指令発生回路１１の機能によって、制御指令発生手段９及び１０９は電力変換器７に対して、逆変換動作、順変換動作及びアクティブフィルタ動作を行わせることが出来る。
【００４０】
図５は、本発明の制御指令発生手段の実施の形態の他の一例の構成を示すブロック回路図である。即ち、図１の負荷電流変動分含有信号発生手段２１の後段の一部と、正弦波信号発生手段２３の出力以降の他の構成である。図１において、負荷電流変動分含有信号発生手段２１の中の平均値回路２５の平均値化信号と交流電源１の出力電圧Ｖ_ＣＳとを乗算器Ｍで乗算した信号に対し減算と加算と減算とが施されている。この加算と減算とは数学と同様にその加減算順序は結果に影響を与えないので、一例として図５に示すように、加算と減算と減算とで構成することが出来る。
【００４１】
図５においては、平均値回路２５の出力と交流電源１の出力電圧Ｖ_ＣＳとを乗算器Ｍで乗算し、その乗算結果と正弦波発生回路２９の出力との加算を加算器Ａで行ない、その出力に対し負荷電流ｉ_Ｌを減算し、その出力に対し更に電力変換器を流れる交流電流ｉ_ＩＮＶを減算して電力変換器７のＰＷＭ回路１５に入力する構成を示している。
【００４２】
図６は、本発明の制御指令発生手段に直流電流制御回路を含ませた実施の一例である。図６において、正弦波信号発生手段２２３は、蓄電池５を定電流で充放電するのに必要な定電流指令を発生する直流電流制御回路３３を更に含んでいる。直流電流制御回路３３は、直流線路４の直流電流ｉ_ＤＣを直流電流検出器１９により検出した出力で直流線路４上の直流電流ｉ_ＤＣを監視し、直流電流ｉ_ＤＣが予め定めた最大電流になると、定電流指令が入力指令の１つとして正弦波発生回路２２９に入力され、正弦波発生回路２２９は定電流指令が入力されているときには、蓄電池を予め定めた最大電流値以下の定電流で充放電するように正弦波信号の振幅を変化させるように構成されている。その他の回路の蓄積電力制御指令発生回路１１、直流電圧制御回路２７の機能や動作の説明は図１及び図４のそれらと同様であり、ここでは説明を省く。この直流電流制御回路３３によって蓄電池の充放電に際しての過大電流による電極の損傷や電池性能の劣化を防ぐことができる。
【００４３】
なお、この図６の直流電圧制御回路２７と正弦波発生回路２２９との間に遅延回路の代表としてＬＰＦ３１が点線で示し挿入されているが、この遅延回路は前述の説明で明らかなように、負荷電流変動分含有信号発生手段か又は正弦波信号発生手段のいずれか一方に設ければよいので、負荷電流変動分含有信号発生手段に遅延回路が設けてある場合には図６のＬＰＦ３１は必要なくなり、負荷電流変動分含有信号発生手段に遅延回路が設けてない場合に図６のように正弦波信号発生手段２２３の中に設けることを意味して、図６では点線で示してある。
【００４４】
図７は、本発明の蓄電池の代わりにコンデンサを用いた場合の実施の一例である。本発明では電力の蓄積を行う蓄電池５を、電力の蓄積状態が電圧のみで監視できるコンデンサ６で置き換えて構成することができる。
【００４５】
図７において、蓄積電力制御指令発生回路１２は直流線路４の直流電圧Ｖ_ＤＣを入力とし、蓄電池の場合と同様に、コンデンサ６の蓄積電力を監視し、コンデンサ６の充電と放電とをいつでも実行できるようにコンデンサ６の蓄積電力を予め定めた基準蓄積電力範囲内に制御するための蓄積電力制御指令を発生する。本発明におけるコンデンサ６には大容量の電気二重層などが適している。また、図７の点線で示したＬＰＦ３１に就いては図６の場合と同様であり、ここでの説明は省く。コンデンサ６を用いる構成では、図７に示すように蓄積電力制御指令発生回路１２の入力には、直流線路４の直流電圧のみで蓄積電力の監視が可能で、コンデンサ６への充放電電流の入力は必要なく、その分蓄積電力制御指令発生回路１２は部品点数が少なくなり、安価になる。
【００４６】
【発明の効果】
本発明によれば、負荷変動に対し応答速度の遅いエンジン発電機などの交流電源を用いても、発電容量に余裕を持たせる必要が無く、交流電源の低価格化と小型化とをもたらす。更に交流電源と負荷とが直結しているので、電力変換効率を高くできる。従来の８０％台を９０数％台に改善出来るので、電源装置の運転費用が少なくて済む。その上、従来の高価な整流器と整流器制御回路とが不要になり、経済的にまた装置サイズの点でも有利になる。
【図面の簡単な説明】
【図１】本発明の交流電源装置の実施の形態の一例の構成を示すブロック回路図である。
【図２】本発明の交流電源装置の実施形態の一例における定常運転時の各部の波形を示す波形図である。
【図３】本発明の交流電源装置の実施形態の一例における負荷投入開放時の各部の波形を示す波形図である。
【図４】本発明の交流電源装置の実施の形態の他の一例の構成を示すブロック回路図である。
【図５】本発明の制御指令発生手段の実施の形態の他の一例の構成を示すブロック回路図である。
【図６】本発明の制御指令発生手段に直流電流制御回路を含ませた実施の一例である。
【図７】本発明の蓄電池にコンデンサを用いた場合の実施の一例である。
【符号の説明】
１交流電源
２給電線路
３負荷
４直流線路
５蓄電池
６コンデンサ
７電力変換器
９，１０９制御指令発生手段
１１，１２蓄積電力制御指令発生回路
１３電力変換手段
１５，１１５ＰＷＭ回路
１７，１８，１９電流検出器
２１負荷電流変動分含有信号発生手段
２３，１２３，２２３正弦波信号発生手段
２５平均値回路
２７直流電圧制御回路
２９，２２９正弦波発生回路
３１遅延回路（ＬＰＦ）
３３直流電流制御回路
Ａ加算器
Ｄ整流器
ｉ_ＣＳ交流電源の出力電流
ｉ_ＤＣ直流線路の充放電電流
ｉ_ＩＮＶ電力変換器を流れる交流電流
ｉ_Ｌ負荷電流
Ｍ乗算器
Ｓ減算器
Ｖ_ＣＳ交流電源の出力電圧
Ｖ_ＤＣ直流線路の直流電圧[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an AC power supply having a characteristic of responding to a load variation with a relatively large delay.
[0002]
[Prior art]
Conventionally, in order to make a high-quality AC power supply apparatus using an AC power supply that responds with a relatively large delay to load fluctuations such as an engine generator (hereinafter abbreviated as EG), A power converter consisting of a rectifier and an inverter is inserted in series with the load, one end of the storage battery is connected to the connection point between these rectifiers and the inverter, AC is constantly rectified and charged, and the charged DC is The inverter was barely supplying high-quality alternating current to the load. The storage battery showed an almost constant voltage in the operating range of the stored power, and the stored power was supplied to cover the delay in the response of the generator (several hundred ms). One such known example is the “operating method of an uninterruptible power supply” disclosed in Japanese Patent Laid-Open No. 54-53236.
[0003]
[Problems to be solved by the invention]
Conventionally, the power generation capacity of the engine generator has been increased to cope with load fluctuations. However, this has a problem that a large generator has to be prepared. Moreover, in this method, since electric power is always supplied via the rectifier, the inverter, and the two power devices, the total power efficiency is about 85%.
[0004]
The objective of this invention is providing the alternating current power supply device which does not require a rectifier and does not need to enlarge the electric power generation capacity of a generator more than necessary.
[0005]
Another object of the present invention is to provide an AC power supply apparatus with better power conversion efficiency than the conventional one.
[0006]
[Means for Solving the Problems]
An AC power supply apparatus according to the present invention includes an AC power supply having characteristics of responding to a load variation with a relatively large delay, a storage battery, a power converter, a control command generating means, and a stored power control command generation. Circuit.
[0007]
The power converter is connected to a power supply line that connects the AC power source and the load and the storage battery, and converts at least a part of the output of the AC power source to DC power to charge the storage battery, and supplies the load to the load. When the power to be used is insufficient, the DC power of the storage battery is reversely converted to AC power, and the reverse power is supplied to the load. In other cases, the reactive power of the feed line is adjusted to output the AC power. The active filter operation is performed to bring the current close to a sine wave.
[0008]
Further, the control command generation means generates a load current fluctuation content signal that generates a load current fluctuation content signal including a load current fluctuation content based on a load current flowing through the load and a sine wave voltage synchronized with the output voltage of the AC power supply. And a DC voltage fluctuation-containing sine wave signal including a DC voltage fluctuation based on the DC voltage of the DC line connecting the power converter and the storage battery and the sine wave voltage synchronized with the output voltage of the AC power supply. The power converter is reversely converted based on the output of the load current fluctuation content signal generating means, the output of the sine wave signal generating means, and the alternating current flowing through the power converter, including the sine wave signal generating means. A current control command for causing the power converter to perform a forward conversion operation and an active filter operation, and a power control command for outputting to the power converter. Further, a delay circuit is provided in either one of the load current fluctuation content signal generating means and the sine wave signal generating means. The delay time or delay characteristic of the delay circuit is determined so as to correspond to the delay in the response speed corresponding to the load fluctuation of the AC power supply. Therefore, the delay time or delay characteristic of the delay circuit is determined for each target AC power source.
[0009]
The stored power control command generation circuit detects the voltage and current of the DC line, monitors the stored power of the storage battery, and stores the stored power of the storage battery in a predetermined reference storage so that the storage battery can be charged and discharged at any time. A stored power control command for controlling within the power range is generated and output to the sine wave signal generating means.
[0010]
In the present invention, the sine wave signal generating means maintains the stored power of the storage battery within the reference stored power range based on the stored power control command, and compensates for the delay in the response characteristic of the AC power supply. A sine wave signal including a command for executing charge / discharge is output. The load current fluctuation content signal generating means outputs a load current fluctuation content signal including a load current fluctuation content. The control command generating means compares the two output signals with the alternating current flowing through the power converter, and outputs a current control command to the power converter. In the power converter, the forward conversion operation, the reverse conversion operation, and the active filter operation are performed based on the current control command.
[0011]
The present invention reduces the burden on the AC power supply by including a delay corresponding to the delay of the response characteristic of the AC power supply in the current control command, and compensates for excess or deficiency of power caused by the delay by charging and discharging the storage battery. . For example, when the load fluctuates in a direction that suddenly increases, if there is a response characteristic delay in the AC power supply, power shortage occurs. Therefore, in this case, the power shortage is compensated by converting the stored power of the storage battery into alternating current by the power conversion means and supplying it to the load. Conversely, when the load suddenly decreases, overpower is generated, but at this time, the power conversion means converts the output of the AC generator into direct current and charges the storage battery to generate the power for the overpower generation. Absorb. In order to enable such an operation, in the present invention, the stored power command generation circuit outputs a stored power control command for maintaining the stored power of the storage battery within the reference stored power range. As a result, when the AC power supply device of the present invention is used, even if the load current fluctuates, the necessary power can be supplied to the load using an AC generator such as an engine generator with a delayed response characteristic. .
[0012]
Furthermore, another AC power supply device of the present invention includes an AC power supply having a characteristic of responding with a relatively large delay to load fluctuations, a storage battery, a power converter, other control command generating means, And an accumulated power control command generation circuit.
[0013]
The power converter is connected to a power supply line that connects the AC power source and the load and the storage battery, and converts at least a part of the output of the AC power source to DC power to charge the storage battery, and supplies the load to the load. When the power to be used is insufficient, the DC power of the storage battery is reversely converted to AC power, and the reverse power is supplied to the load. In other cases, the reactive power of the feed line is adjusted to output the AC power. The active filter operation is performed to bring the current close to a sine wave.
[0014]
The other control command generating means is based on a load current detecting means for detecting a load current flowing in the load, a sine wave voltage synchronized with the DC voltage of the DC line connecting the power converter and the storage battery and the output voltage of the AC power supply. Including a sine wave signal generating means for generating a DC voltage fluctuation-containing sine wave signal including a DC voltage fluctuation component, an output of the load current detecting means, an output of the sine wave signal generating means, and an alternating current flowing through the power converter Based on the current, a current control command for causing the power converter to perform a reverse conversion operation and a current control command for causing the power converter to perform a forward conversion operation and an active filter operation are output to the power converter. Composed. Further, the sine wave signal generating means is provided with a delay circuit, and a delay corresponding to the delay of the response characteristic of the AC power supply is included in the current control command.
[0015]
The stored power control command generation circuit monitors the stored power of the storage battery, and controls the stored power of the storage battery within a predetermined reference stored power range so that the storage battery can be charged and discharged at any time. Is generated.
[0016]
The sine wave signal generating means of the other control command generating means of the present invention compensates for the delay in the response characteristic of the AC power supply while maintaining the stored power of the storage battery within the reference stored power range based on the stored power control command. A sine wave signal including a command for executing charge / discharge of the storage battery necessary for the output is generated, the output thereof, the output of the load current detecting means, and these two output signals are compared with the alternating current flowing through the power converter. The current control command is output to the power converter. The power converter performs forward conversion operation, reverse conversion operation, and active filter operation based on the current control command, and can control the generator current to be a sine wave in accordance with the variation of the load current. it can.
[0017]
Furthermore, in the present invention, the sine wave signal generating means further includes a direct current control circuit for generating a constant current command necessary for charging and discharging the storage battery with a constant current, and the constant current command is one of the input commands. When the constant current command is input, the sine wave generation circuit changes the amplitude of the sine wave signal so that the storage battery is charged with a constant current equal to or less than a predetermined maximum current value. It is configured. As a result, when charging or discharging the storage battery, it is possible to prevent electrode damage and battery performance deterioration due to excessive current.
[0018]
Furthermore, in the present invention, the storage battery for storing power can be replaced with a capacitor whose power storage state can be monitored only by voltage. A large-capacity electric double layer or the like is suitable for the capacitor in the present invention. In the configuration using the capacitor, the stored power control command generation circuit can be monitored only by the DC voltage of the DC line, and the input of charge / discharge current to the capacitor 6 is not required, and the stored power control command is accordingly supplied. The generator circuit has fewer parts and is less expensive.
[0019]
The stored power control command generation circuit according to the present invention monitors the stored power of the storage battery, and stores it to control the stored power of the storage battery within a predetermined reference stored power range so that the storage battery can be charged and discharged at any time. Generate power control commands. In other words, unlike a normal charging circuit that charges the battery at a constant charge completion state, the charging state in the present invention can supply a current that is insufficient at the load or, on the contrary, can absorb an excess current at the load. Always keep the state of charge in an intermediate charge state. That is, the circuit is configured to control within a predetermined reference accumulated power range.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.
[0021]
FIG. 1 is a block circuit diagram showing a configuration of an example of an embodiment of an AC power supply apparatus according to the present invention. The AC power supply device shown in FIG. 1 has an AC power supply 1 having a characteristic of responding with a relatively large delay to fluctuations in the load 3, a storage battery 5, a power converter 7, and a control command generating means 9. And a stored power control command generation circuit 11.
[0022]
The AC power source 1 in this example is an engine generator. The load 3 is a general load such as a motor or a heater. The power converter 7 includes a power conversion unit 13 and a PWM circuit 15, and the power conversion unit 13 includes a plurality of control semiconductor elements. The power conversion means 13 forward-converts at least a part of the output of the AC power source 1 to DC power and charges the storage battery 5 through the DC line 4, and when the power to be supplied to the load 3 is insufficient Reverse conversion operation for reversely converting DC power of the storage battery 5 to AC power and supplying insufficient power to the load 3, and adjusting the reactive power of the feed line 2 at other times to output current i of the AC power source 1 _CS The active filter operation for bringing the sine wave closer to a sine wave is performed in accordance with the output of the control command generating means 9 described later. Since the configuration of such power conversion means 13 is well known, details are omitted. The PWM circuit 15 performs PWM control on the plurality of control semiconductor elements of the power conversion unit 13 in accordance with the output of the control command generation unit 9.
[0023]
The control command generation means 9 includes a load current fluctuation content signal generation means 21 and a sine wave signal generation means 23. This load current fluctuation content signal generating means 21 is connected to the load current i flowing through the load 3. _L Is detected by the load current detecting means 17, and the detected load current i _L Is averaged including a delay time by an averaging circuit 25 comprising a rectifier D and a low-pass filter (hereinafter abbreviated as LPF) 31 and converted into a DC voltage signal. This DC voltage signal and the output voltage V of the AC power supply 1 _CS And the load current i for the signal multiplied by the multiplier M _L Is obtained by a subtracter S and output as a load current fluctuation content signal. The sine wave signal generating means 23 is a DC voltage V of the DC line 4. _DC A DC voltage control circuit 27 that outputs a DC voltage control command indicating a voltage difference between the reference voltage and a predetermined reference voltage; an input command and an output voltage V of the AC power supply 1 _CS Based on the output voltage V of the AC power supply 1 _CS And a sine wave generation circuit 29 for outputting a sine wave signal whose phase is synchronized and whose amplitude changes in accordance with an input command. The input commands include a DC voltage control command output from the DC voltage control circuit 27 and a stored power control command output from the stored power control command generation circuit 11. The sine wave generation circuit 29 compensates for a delay in the response characteristic of the AC power source 1 based on the DC voltage control command while maintaining the stored power of the storage battery 5 within the reference stored power range based on the stored power control command. Is configured to output a sine wave signal including a command for executing charging / discharging of the storage battery 5 as a change in amplitude. The output of the load current fluctuation content signal generating means 21 and the output of the sine wave signal generating means 23 are added by the adder A, and the AC current i flowing through the power converter 7 is added to the output. _INV Is detected by the current detector 18 and is subtracted by the output thereof, and a current control command for causing the power converter 7 to perform the reverse conversion operation and a current control for causing the power converter 7 to perform the forward conversion operation and the active filter operation. The command is configured to be output to the PWM circuit 15 of the power converter 7.
[0024]
The stored power control command generation circuit 11 monitors the stored power of the storage battery 5 and controls the stored power of the storage battery 5 within a predetermined reference stored power range so that the storage battery 5 can be charged and discharged at any time. Generate stored power control command. Therefore, the DC voltage V of the DC line 4 _DC And charge / discharge current i _DC Is detected by the current detector 19 and its output is monitored. In other words, unlike a normal charging circuit that charges in a state where charging is always completed, in the present invention, in order to supply a current deficient in the load 3 or to absorb a current excessive in the load 3, The charging state of the storage battery 5 is always controlled to the intermediate charging state, that is, within a predetermined reference stored power range.
[0025]
In the present invention, either one of the load current fluctuation content signal generating means 21 and the sine wave signal generating means 23 is provided with a delay circuit, and the delay corresponding to the delay of the response characteristic of the AC power supply 1 is set to the current control command and voltage. In FIG. 1, an LPF 31 is included in the load current fluctuation content signal generating means 21, and this LPF 31 serves as a delay circuit.
[0026]
Further, the load current fluctuation content signal generating means 21 in FIG. 1 is configured by using the averaging circuit 25. However, even if an effective value circuit is used instead of the averaging circuit 25, the load current fluctuation content is included. A signal generating means can be configured. This is because the effective value circuit itself has a delay element, and almost the same effect can be obtained.
[0027]
The operation of FIG. 1 will be described with reference to current waveform diagrams. FIG. 2 is a waveform diagram showing waveforms of respective parts during steady operation in an example of the embodiment of the AC power supply apparatus of the present invention.
[0028]
In FIG. 2, load 3 is a rectifier, and output voltage V of AC power supply 1. _CS When a certain voltage level is reached, the load current i _L Is a non-linear load that flows out. Load current i _L Is the output current i of the AC power source 1 _CS The deficiency is supplied from the storage battery side. Also, the output voltage V of the AC power supply 1 _CS Output current i of AC power supply 1 until a certain level is reached _CS Does not flow into the load, but is absorbed by the storage battery as an excess. AC current i flowing through this power converter 7 _INV I _INV = I _CS -I _L The output current i of the AC power supply 1 _CS Since the power converter 7 is controlled by the control command generation means 9 so that becomes a sine wave, a current waveform i as shown in FIG. _INV become. FIG. 2A shows a case where the current of the shortage and the excess has just canceled each other, and is a case where the storage battery current is zero and no current flows through the storage battery 5 as a whole. _INV A dotted line showing the storage battery current is seen on the base line. FIG. 2 (B) shows the case where the current of the shortage and the excess does not cancel each other, and the upper diagram of FIG. 2 (B) shows the case where the current flows into the storage battery 5 as a whole and the storage battery 5 is charged. It is. The dotted line in the above figure shows the charging current. The lower part of FIG. 6B shows a case where current flows out from the storage battery 5 as a whole and the storage battery 5 is discharged, and the dotted line in the lower part shows the discharge current.
[0029]
FIG. 3 is a waveform diagram showing the waveforms of the respective parts at the time of releasing the load in the example of the AC power supply apparatus according to the present invention. In FIG. 3, the load 3 is a rectifier as in FIG. 2, is a non-linear load with respect to the voltage, and the storage battery 5 is a case where the storage battery current is zero. FIG. 3A shows the waveforms of the respective parts when the load is turned on. At the time of turning on, the AC power source 1 such as an engine generator is not sufficiently rotated, so that the output voltage V _CS Output current i _CS Insufficient power is supplied from the storage battery side. Therefore, the current waveform i _INV Is the load current i _L And has almost the same waveform. As the engine speed gradually approaches normal with time, the output voltage V _CS Output current i _CS Becomes a regular output, and the current waveform i _INV Is the current waveform i in FIG. _INV It becomes the same waveform. FIG. 3B is a waveform of each part when the load is released, and the load current i when the load is released. _L = 0, so from that moment i _INV = I _CS And it appears in the figure. Naturally, when the load is released, the generator engine decelerates and stops at the same time, and the output current i _CS Becomes an attenuation waveform as shown in the figure.
[0030]
In the description of FIGS. 2 and 3, the load is the output voltage V _CS A non-linear rectifier is described, but the output current i _CS Even when a non-linear saturable reactance is used as a load, or even when a load is linear with respect to voltage or current and the current waveform is delayed or advanced with respect to the voltage waveform, the same operation is performed. Output current i of power supply 1 _CS Output voltage V _CS The power converter 7 is controlled by the control command generating means 9 so as to be a sine wave in phase with the control command. The reason is that the sine wave generating circuit 29 is connected to the output voltage V _CS This is because a sine wave signal synchronized with the power converter 7 is sent to the power converter 7, and the PWM circuit 15 of the power converter 7 controls the power converter 13.
[0031]
2 and 3 have been described for the AC power supply apparatus of FIG. 1, but the same applies to the AC power supply apparatus of the present invention after FIG. 4 described later. Here, the AC power supply apparatus of FIG. The power supply device has been described as a representative example.
[0032]
FIG. 4 is a block circuit diagram showing the configuration of another example of the embodiment of the AC power supply apparatus of the present invention. In the AC power supply apparatus of the present invention, blocks having the same reference numerals as those in FIG. 1 are blocks having the same functions in FIG. The same applies to FIG.
[0033]
In FIG. 4, another AC power supply apparatus of the present invention includes an AC power supply 1 having a characteristic of responding with a relatively large delay to fluctuations in the load 3, a storage battery 5, a power converter 7, and a control command. The generating means 109 and the stored power control command generating circuit 11 are configured.
[0034]
The power converter 7 includes a power conversion unit 13 and a PWM circuit 15, and the power conversion unit 13 includes a plurality of control semiconductor elements. A forward conversion operation for charging the storage battery 5 by converting at least a part of the output of the alternating current power supply 1 to direct current power, connected to the feed line 2 and the storage battery 5 that connect the alternating current power supply 1 and the load 3, and the load 3 When the power to be supplied to the battery is insufficient, the DC power of the storage battery 5 is reversely converted to AC power, and the reverse power is supplied to the load 3, and the reactive power of the feeder line 2 is adjusted at other times. The output current i of the AC power source 1 _CS The active filter operation is performed to bring sine wave closer to a sine wave. The PWM circuit 15 generates a PWM control signal for PWM control of a plurality of control semiconductor elements of the power conversion means 13.
[0035]
The control command generation means 109 is a load current i flowing through the load 3. _L DC voltage V of the DC line 4 connecting the load current detecting means 17 for detecting the power, the power converter 7 and the storage battery 5. _DC And output voltage V of AC power supply _CS Sine wave signal generating means 123 for generating a DC voltage fluctuation-containing sine wave signal including a DC voltage fluctuation based on a sine wave voltage synchronized with the sine wave voltage, and an AC current i flowing through the power converter _INV And AC current detecting means 18 for detecting. This sine wave signal generating means 123 is connected to the DC voltage V of the DC line 4. _DC A DC voltage control circuit 27 that outputs a DC voltage control command indicating a voltage difference between the reference voltage and a predetermined reference voltage; an input command and an output voltage V of the AC power supply 1 _CS Based on the output voltage V of the AC power supply 1 _CS And a sine wave generation circuit 29 for outputting a sine wave signal whose phase is synchronized and whose amplitude changes in accordance with an input command. The input command includes a DC voltage control command and a stored power control command. The sine wave generation circuit 29 compensates for a delay in the response characteristic of the AC power supply 1 based on the DC voltage control command while maintaining the stored power of the storage battery 5 within the reference stored power range based on the stored power control command. Is configured to output a sine wave signal including a command for executing charging / discharging of the storage battery 5 as a change in amplitude. Further, the LPF constituting the delay circuit 31 is arranged between the DC voltage control circuit 27 and the sine wave generation circuit 29, and thereby the delay corresponding to the delay of the response characteristic of the AC power supply 1 is set as a current control command and a voltage control command. Included. In response to the difference signal between the output of the sine wave signal generating means 123 and the output of the load current detecting means 17, an alternating current i flowing through the power converter 7 _INV Is used as an output signal of the control command generation means 109 as an input signal of the PWM circuit 15 of the power converter 7. The output of the PWM circuit 15 is configured to be applied to the power conversion means 13. In the power converter 7, an inverse conversion operation, a forward conversion operation, and an active filter operation are performed based on the current control command, and the load current i _L The generator current i adapts to fluctuations _CS Can be controlled to be a sine wave.
[0036]
The stored power control command generation circuit 11 monitors the stored power of the storage battery 5 and controls the stored power of the storage battery 5 within a predetermined reference stored power range so that the storage battery 5 can be charged and discharged at any time. Generate stored power control command.
[0037]
As shown in FIGS. 1 and 4, the configuration of the present invention is novel. Conventionally, a rectifier and an inverter are inserted in series between the AC power source 1 and the load 3. Accordingly, alternating current is always converted to direct current, and the direct current is always reconverted to alternating current. Each of these power conversion efficiencies is about 90%, and the total efficiency of the two in series has deteriorated to about 81%. Even if various ideas were added, it was 85% with 20KVA scale engine generator power. On the other hand, in the present invention, as described above, the AC power source 1 and the load 3 are directly connected by the feeder line 2 and are not affected by the poor conversion efficiency at all times. Then, an inverter type power converter 7 is branched from the feed line 2 and connected to the storage battery 5 via the DC line 4 at the tip of the power converter 7, and the load current i _L Charge / discharge current i of the storage battery 5 _DC Therefore, 97% is obtained with an engine generator power supply with a power conversion efficiency of 20 KVA. Thus, not only is the structure new, but the new structure also provides high power conversion efficiency. Therefore, the operating cost of the power supply device can be reduced because of the high efficiency.
[0038]
Further, according to the present invention, even if an AC power source such as an engine generator having a slow response speed with respect to load fluctuations is used, it is not necessary to provide a margin for the power generation capacity, and an AC power source device including the engine generator correspondingly. The price can be reduced and the size can be reduced. Further, the configuration in which the power source and the load are directly connected eliminates the need for a conventional expensive rectifier, and also eliminates the need for a control circuit for the rectifier, which has a greater effect in terms of economy and apparatus size.
[0039]
The key circuit of the present invention that brings about these effects is the stored power control command generation circuit 11. As described above, the accumulated power control command generation circuit 11 always supplies the charge state of the storage battery 5 to the intermediate charge so that it can supply the current deficient in the load 3 or absorb the excess current in the load 3. It is configured to control within a state, that is, within a predetermined reference accumulated power range. With the function of the stored power control command generation circuit 11, the control command generation means 9 and 109 can cause the power converter 7 to perform an inverse conversion operation, a forward conversion operation, and an active filter operation.
[0040]
FIG. 5 is a block circuit diagram showing the configuration of another example of the embodiment of the control command generating means of the present invention. That is, a part of the subsequent stage of the load current fluctuation content signal generating means 21 in FIG. 1 and other configurations after the output of the sine wave signal generating means 23. In FIG. 1, the averaged signal of the average value circuit 25 in the load current fluctuation content signal generating means 21 and the output voltage V of the AC power source 1 are shown. _CS Are subtracted, added, and subtracted from the signal obtained by multiplying the signal by the multiplier M. As in mathematics, the addition and subtraction do not affect the result, and the addition and subtraction can be constituted by addition, subtraction and subtraction as shown in FIG.
[0041]
In FIG. 5, the output of the average value circuit 25 and the output voltage V of the AC power supply 1 _CS Are multiplied by the multiplier M, and the addition result and the output of the sine wave generation circuit 29 are added by the adder A, and the load current i is applied to the output. _L And the alternating current i flowing through the power converter further to the output _INV Is subtracted and input to the PWM circuit 15 of the power converter 7.
[0042]
FIG. 6 shows an example in which a direct current control circuit is included in the control command generation means of the present invention. In FIG. 6, the sine wave signal generating means 223 further includes a direct current control circuit 33 that generates a constant current command necessary for charging and discharging the storage battery 5 with a constant current. The direct current control circuit 33 is a direct current i of the direct current line 4. _DC DC current i on the DC line 4 with the output detected by the DC current detector 19 _DC DC current i _DC Becomes a predetermined maximum current, a constant current command is input to the sine wave generation circuit 229 as one of the input commands. When the constant current command is input, the sine wave generation circuit 229 sets the storage battery to a predetermined maximum The amplitude of the sine wave signal is changed so as to charge and discharge at a constant current equal to or less than the current value. The functions and operations of the stored power control command generation circuit 11 and the DC voltage control circuit 27 of other circuits are the same as those in FIGS. 1 and 4 and will not be described here. This direct current control circuit 33 can prevent damage to electrodes and deterioration of battery performance due to excessive current during charging and discharging of the storage battery.
[0043]
An LPF 31 is inserted as a representative delay circuit between the DC voltage control circuit 27 and the sine wave generation circuit 229 shown in FIG. 6 with a dotted line. As is apparent from the above description, this delay circuit is Since the load current variation containing signal generating means or the sine wave signal generating means may be provided, the LPF 31 of FIG. 6 is necessary when the delay circuit is provided in the load current fluctuation containing signal generating means. In FIG. 6, this means that the load current fluctuation containing signal generating means is provided in the sine wave signal generating means 223 as shown in FIG. 6 when no delay circuit is provided.
[0044]
FIG. 7 is an example of implementation when a capacitor is used instead of the storage battery of the present invention. In the present invention, the storage battery 5 that stores power can be replaced with a capacitor 6 that can monitor the power storage state only by voltage.
[0045]
In FIG. 7, the stored power control command generation circuit 12 has a DC voltage V of the DC line 4. _DC As in the case of the storage battery, the stored power of the capacitor 6 is monitored, and the stored power of the capacitor 6 is controlled within a predetermined reference stored power range so that charging and discharging of the capacitor 6 can be performed at any time. A stored power control command is generated. A large-capacity electric double layer or the like is suitable for the capacitor 6 in the present invention. Further, the LPF 31 indicated by the dotted line in FIG. 7 is the same as that in FIG. 6, and description thereof is omitted here. In the configuration using the capacitor 6, as shown in FIG. 7, the stored power can be monitored only by the DC voltage of the DC line 4 at the input of the stored power control command generation circuit 12, and the charge / discharge current is input to the capacitor 6. Accordingly, the stored power control command generation circuit 12 is reduced in the number of parts and thus becomes inexpensive.
[0046]
【The invention's effect】
According to the present invention, even if an AC power source such as an engine generator having a slow response speed with respect to load fluctuations is used, it is not necessary to provide a margin for the power generation capacity, resulting in a reduction in price and size of the AC power source. Furthermore, since the AC power supply and the load are directly connected, the power conversion efficiency can be increased. Since the conventional 80% range can be improved to the 90% range, the operating cost of the power supply device can be reduced. In addition, the conventional expensive rectifier and the rectifier control circuit are not required, which is advantageous in terms of economy and apparatus size.
[Brief description of the drawings]
FIG. 1 is a block circuit diagram showing a configuration of an example of an embodiment of an AC power supply apparatus of the present invention.
FIG. 2 is a waveform diagram showing waveforms at various parts during steady operation in an example of an embodiment of an AC power supply apparatus according to the present invention.
FIG. 3 is a waveform diagram showing waveforms at various parts when a load is released in an example of an embodiment of an AC power supply apparatus of the present invention.
FIG. 4 is a block circuit diagram showing a configuration of another example of the embodiment of the AC power supply device of the present invention.
FIG. 5 is a block circuit diagram showing a configuration of another example of the embodiment of the control command generation means of the present invention.
FIG. 6 is an example of an embodiment in which a direct current control circuit is included in the control command generation means of the present invention.
FIG. 7 is an example of implementation when a capacitor is used in the storage battery of the present invention.
[Explanation of symbols]
1 AC power supply
2 Feed line
3 Load
4 DC line
5 battery
6 capacitors
7 Power converter
9,109 Control command generating means
11, 12 Accumulated power control command generation circuit
13 Power conversion means
15,115 PWM circuit
17, 18, 19 Current detector
21 Load current fluctuation content signal generating means
23, 123, 223 Sinusoidal signal generating means
25 Average circuit
27 DC voltage control circuit
29,229 sine wave generation circuit
31 Delay circuit (LPF)
33 DC current control circuit
A Adder
D Rectifier
i _CS Output current of AC power supply
i _DC DC line charge / discharge current
i _INV AC current flowing through power converter
i _L Load current
M multiplier
S subtractor
V _CS AC power supply output voltage
V _DC DC voltage of DC line

Claims

An AC power supply having a characteristic of responding to a load variation with a relatively large delay;
A storage battery,
A power supply line connecting the AC power supply and the load and a storage battery connected to the storage battery, forward conversion operation for converting at least a part of the output of the AC power supply to DC power and charging the storage battery, and supplying the load When the power to be used is insufficient, the DC power of the storage battery is converted back to AC power, and the reverse power is supplied to the load. In other cases, the reactive power of the feeder line is adjusted. A power converter that performs an active filter operation that approximates an output current of the AC power supply to a sine wave;
A load current fluctuation containing signal generating means for generating a load current fluctuation containing signal including a fluctuation of the load current based on a load current flowing through the load and a sine wave voltage synchronized with an output voltage of the AC power supply; and A DC voltage fluctuation-containing sine wave signal including the DC voltage fluctuation is generated based on a DC voltage of a DC line connecting the power converter and the storage battery and a sine wave voltage synchronized with the output voltage of the AC power supply. Sine wave signal generating means, and based on the output of the load current fluctuation content signal generating means, the output of the sine wave signal generating means, and the alternating current flowing through the power converter, the power converter A current control command for performing a reverse conversion operation and a current control command for causing the power converter to perform a forward conversion operation and the active filter operation are output to the power converter. And the control command generating means that,
Provided in any one of the load current fluctuation content signal generating means and the sine wave signal generating means of the control command generating means, and including a delay corresponding to the delay of the response characteristic of the AC power supply in the current control command Delay circuit,
The stored power for monitoring the stored power of the storage battery and generating a stored power control command for controlling the stored power of the storage battery within a predetermined reference stored power range so that the storage battery can be charged and discharged at any time. A control command generation circuit,
The sine wave signal generating means maintains the stored power of the storage battery within the reference stored power range based on the stored power control command, and compensates for a delay in the response characteristic of the AC power supply. An AC power supply apparatus configured to output a sine wave signal including a command for executing charge / discharge of a storage battery.

The power converter includes a power conversion means and a PWM circuit that generates a PWM control signal for PWM control of a plurality of control semiconductor elements constituting the power conversion means,
The load current fluctuation content signal generating means, a load current detector for detecting the load current, and converting the detected load current into a DC voltage signal by averaging or effective value including a delay time, A signal obtained by multiplying a DC voltage signal by an output voltage of the AC power supply is configured to output a difference signal between the load current and the load current fluctuation content signal,
The sine wave signal generating means is based on a DC voltage control circuit that outputs a DC voltage control command indicating a differential voltage between a DC voltage of the DC line and a predetermined reference voltage, an input command, and an output voltage of the AC power supply. A sine wave generation circuit that outputs a sine wave signal whose phase is synchronized with the output voltage of the AC power supply and whose amplitude changes in accordance with the input command,
As the input command, the DC voltage control command and the stored power control command are input to the sine wave generation circuit,
The sine wave generator circuit delays the response characteristic of the AC power source based on the DC voltage control command while maintaining the stored power of the storage battery within the reference stored power range based on the stored power control command. Configured to output a sine wave signal including a change in the amplitude as a command to execute charge / discharge of the storage battery necessary to compensate,
The control command generation means outputs a difference signal between an addition signal of the output of the load current fluctuation content signal generation means and the output of the sine wave signal generation means and the alternating current flowing through the power converter of the PWM circuit. The AC power supply apparatus according to claim 1, wherein the AC power supply apparatus is configured to output as an input signal.

An AC power supply having a characteristic of responding to a load variation with a relatively large delay;
A storage battery,
A power supply line connecting the AC power supply and the load and a storage battery connected to the storage battery, forward conversion operation for converting at least a part of the output of the AC power supply to DC power and charging the storage battery, and supplying the load When the power to be used is insufficient, the DC power of the storage battery is converted back to AC power, and the reverse power is supplied to the load. In other cases, the reactive power of the feeder line is adjusted. A power converter that performs an active filter operation that approximates an output current of the AC power supply to a sine wave;
The DC voltage based on a sine wave voltage synchronized with a load current detecting means for detecting a load current flowing through the load, a DC voltage of a DC line connecting the power converter and the storage battery, and an output voltage of the AC power supply Including a sine wave signal generating means for generating a sine wave signal containing a DC voltage fluctuation component including a fluctuation amount of the current, an output of the load current detecting means, an output of the sine wave signal generating means, and an alternating current flowing through the power converter And a current control command for causing the power converter to perform the reverse conversion operation and a current control command for causing the power converter to perform a forward conversion operation and the active filter operation to the power converter. Control command generating means for outputting;
A delay circuit provided in the sine wave signal generating means of the control command generating means, and including a delay corresponding to a delay in response characteristics of the AC power supply in the current control command;
The stored power for monitoring the stored power of the storage battery and generating a stored power control command for controlling the stored power of the storage battery within a predetermined reference stored power range so that the storage battery can be charged and discharged at any time. A control command generation circuit,
The sine wave signal generating means maintains the stored power of the storage battery within the reference stored power range based on the stored power control command, and compensates for a delay in the response characteristic of the AC power supply. An AC power supply apparatus configured to output a sine wave signal including a command for executing charge / discharge of a storage battery.

The sine wave signal generating means is based on a DC voltage control circuit that outputs a DC voltage control command indicating a differential voltage between a DC voltage of the DC line and a predetermined reference voltage, an input command, and an output voltage of the AC power supply. A sine wave generation circuit that outputs a sine wave signal whose phase is synchronized with the output voltage of the AC power supply and whose amplitude changes in accordance with the input command,
As the input command, the DC voltage control command and the stored power control command are input to the sine wave generation circuit,
The sine wave generator circuit delays the response characteristic of the AC power source based on the DC voltage control command while maintaining the stored power of the storage battery within the reference stored power range based on the stored power control command. Configured to output a sine wave signal including a change in the amplitude as a command to execute charge / discharge of the storage battery necessary to compensate,
A low pass filter constituting the delay circuit is disposed between the DC voltage control circuit and the sine wave generation circuit;
The power converter includes a power conversion means and a PWM circuit that generates a PWM control signal for PWM control of a plurality of control semiconductor elements constituting the power conversion means,
The control command generating means outputs a difference signal between the output of the load current detecting means and the output of the sine wave signal generating means and the alternating current flowing through the power converter as an input signal of the PWM circuit. The AC power supply apparatus according to claim 3, wherein the AC power supply apparatus is configured to be configured as described above.

The sine wave signal generating means further includes a direct current control circuit for generating a constant current command necessary for charging the storage battery with a constant current,
The constant current command is input to the sine wave generation circuit as one of the input commands,
5. The sine wave generation circuit is configured to change the amplitude of the sine wave signal so that the storage battery is charged and discharged with a constant current when the constant current command is input. The AC power supply described.

6. The AC power supply apparatus according to claim 1, wherein the storage battery that stores the electric power is replaced with a capacitor that can monitor the electric power storage state only by voltage.