JP3787965B2

JP3787965B2 - Power supply

Info

Publication number: JP3787965B2
Application number: JP16918897A
Authority: JP
Inventors: 裕岩堀; 博市新堀; 務塩見; 俊朗中村; 晋二日妻
Original assignee: Matsushita Electric Works Ltd
Current assignee: Panasonic Electric Works Co Ltd
Priority date: 1997-06-25
Filing date: 1997-06-25
Publication date: 2006-06-21
Anticipated expiration: 2017-06-25
Also published as: JPH1116689A

Description

【０００１】
【発明の属する技術分野】
本発明は、複数の電力変換を行うスイッチング回路がスイッチング素子を共用する電源装置に関するものであり、さらに詳しくはチョッパ回路により交流電源からの入力歪みを改善するとともに負荷回路には交流電源に同期した低周波出力を供給するインバータ回路を備える電源装置に関するものである。
【０００２】
【従来の技術】
図２０は従来の電源装置の回路図である。この電源装置では、スイッチング素子Ｑ１，Ｑ２の直列回路と、スイッチング素子Ｑ３，Ｑ４の直列回路と、ダイオードＤ５，Ｄ６の直列回路とが、電解コンデンサＣの両端間に並列に接続されている。また、スイッチング素子Ｑ１，Ｑ２の接続点とスイッチング素子Ｑ３，Ｑ４の接続点との間にはインダクタＬ２と負荷回路Ｚが接続されており、ダイオードＤ５，Ｄ６の接続点Ａとスイッチング素子Ｑ１，Ｑ２の接続点との間には、交流電源ＡＣとインダクタＬ１とが接続されている。なお、各スイッチング素子Ｑ１〜Ｑ４は逆並列のダイオードＤ１〜Ｄ４をそれぞれ備えている。
【０００３】
まず、この回路の動作の一例を、以下に示す。入力の交流電源のダイオードＤ１、Ｄ２の接続点側が負極性の場合、図２１（ａ）に示すように、スイッチング素子Ｑ２及びＱ３がＯＮ、スイッチング素子Ｑ１及びＱ４がＯＦＦの期間（図２２（ａ）参照）と、スイッチング素子Ｑ１及びＱ３がＯＮ、スイッチング素子Ｑ２及びＱ４がＯＦＦの期間（図２２（ｂ）参照）と、すべてのスイッチング素子がＯＦＦの期間（図２２（ｃ）参照）が順にあり、それらを周期的に繰り返すように動作する。
【０００４】
また、入力の交流電源のダイオードＤ１、Ｄ２の接続点側が正極性の場合、図２１（ｂ）に示すように、スイッチング素子Ｑ１及びＱ４がＯＮ、スイッチング素子Ｑ２及びＱ３がＯＦＦの期間（図２３（ａ）参照）と、スイッチング素子Ｑ２及びＱ４がＯＮ、スイッチング素子Ｑ１及びＱ３がＯＦＦの期間（図２３（ｂ）参照）と、すべてのスイッチング素子がＯＦＦの期間（図２３（ｃ）参照）が順にあり、それらを周期的に繰り返すように動作する。以上のごとく回路が動作することにより、負荷Ｚには入力の商用周波電源ＡＣと同期した矩形波状の電圧を印加するものである。
【０００５】
そして、兼用されたスイッチング素子Ｑ１、Ｑ２には２つのループの電流が同時に逆向きに流れることで、スイッチング素子に実質的に流れる電流を少なくして、スイッチング素子の損失を低減し、発熱等を抑えて、小形且つ低コストの電源装置を提供するものである。
【０００６】
【発明が解決しようとする課題】
一般に高圧放電灯は、放電を開始するまでの間は極めてインピーダンスの高い状態（以下「無負荷状態」と称する）である。放電灯を始動するには、その無負荷状態において、ランプ印加電圧に高圧パルス電圧を重畳して放電を開始させる。放電開始直後は管内の温度が低いため、管内の圧力が低く、数オーム程度の極めて低いインピーダンスの状態（すなわち低ランプ電圧状態）となり、その放電状態を持続することで、温度の上昇とともに圧力も高くなり、電気的なインピーダンスも上昇し、安定な点灯状態に移行する。このように、高圧放電灯を安定に始動し点灯させるには、高圧パルスを印加する際に２００Ｖから４００Ｖ程度の電圧を印加した状態を作る必要がある。また、高圧放電灯は放電の安定化のためにコンデンサを並列に接続し、電流の高周波成分をバイパスさせて放電灯に高周波電流が流れないようにする必要がある。これは音響的共鳴現象を発生させないためである。
【０００７】
以上のような、高圧放電灯を負荷として使用する場合の始動時の動作等について従来例では考慮されておらず、電源電圧と負荷に印加する電圧等に関しても考慮されていない。そこで、本発明では負荷に高圧放電灯を使用する場合における動作等を提案しようとするものである。
【０００８】
【課題を解決するための手段】
本発明によれば、上記の課題を解決するために、交流電源を入力され少なくとも１つのスイッチング素子と、少なくとも１つの第１のインダクタとを備えた少なくとも１つの昇圧チョッパ回路と、
少なくとも１つの第２のインダクタと負荷回路を含み、前記昇圧チョッパ回路に平滑コンデンサを介して接続された少なくとも１つの降圧チョッパ回路とを備え、
少なくとも１つの前記昇圧チョッパ回路のスイッチング素子と前記降圧チョッパ回路のスイッチング素子を兼用し、昇圧動作時の電流と降圧動作時の電流が前記兼用されているスイッチング素子に互いに打ち消す方向に流れる期間を少なくとも生ずるように動作させる制御回路を備え、負荷には入力交流電圧と同期した交流電圧を印加する電源装置において、
定常時よりも負荷抵抗の高い略無負荷時（負荷が電力をほとんど消費しない状態）に、入力電源と第１のインダクタの直列回路の両端を短絡して、入力電源のエネルギーを第１のインダクタに蓄積する期間の後、第１のインダクタに蓄積したエネルギーを入力電源を通じて平滑コンデンサに放出する期間を含む周期でスイッチング動作を行うことを特徴とするものである。
【０００９】
【発明の実施の形態】
（実施例１）
図１は本発明の第１の実施例の回路図である。この回路は、インバータ回路の部分と制御回路の部分よりなっている。インバータ回路の部分は、スイッチング素子Ｑ１、Ｑ２とインダクタＬ１及びダイオードＤ５、Ｄ６による入力電流歪み改善用の昇圧チョッパ回路と、スイッチング素子Ｑ１〜Ｑ４とインダクタＬ２による負荷電流限流用の降圧チョッパ回路とを備えている。以下、その回路構成について説明すると、平滑コンデンサＣ１と並列に、スイッチング素子Ｑ１、Ｑ２の直列回路、スイッチング素子Ｑ３、Ｑ４の直列回路、ダイオードＤ５、Ｄ６の直列回路が接続されている。スイッチング素子Ｑ１、Ｑ２の接続点とスイッチング素子Ｑ３、Ｑ４の接続点との間には、放電灯ＬａｍｐとコンデンサＣ２の並列回路がインダクタＬ２を介して接続されている。ダイオードＤ５、Ｄ６の接続点とスイッチング素子Ｑ１、Ｑ２の接続点との間には、交流電源ＡＣとインダクタＬ１が直列回路を構成して接続されている。
【００１０】
極性判別回路１は、入力電源ＡＣの極性を検出し、その極性に応じた信号を出力する。点灯判別回路２は、ランプが点灯しているか否かを検出し、不点灯時には信号を出力する。タイマー回路３は点灯判別回路２からの入力信号があったとき（不点灯時）に、入力電源ＡＣの電圧がゼロクロスした時点からΔｔの期間、タイマー信号を出力し、点灯判別回路２からの入力信号が無いとき（点灯時）には何も出力しない。図２（ａ）に不点灯時の信号波形を、図２（ｂ）に点灯時の信号波形を示す。
【００１１】
発振回路Ａは昇圧動作時の駆動信号の基準となる信号（図３参照）を発生させるものであり、発振回路Ｂは定常時の駆動信号の基準となる信号（図４参照）を発生させるものである。信号切り替え回路４は電源ＡＣの極性にしたがって、スイッチング素子の動作極性を切り替えるとともに、不点灯時には電源ＡＣの極性が変わった時点から上述のタイマー信号によりΔｔの間、昇圧動作を行う期間を挿入し、その後、定常時の駆動信号に切り替えるように動作する。その結果、スイッチング素子Ｑ１〜Ｑ４の駆動波形としては、昇圧時は図３のようになり、定常時の駆動波形は図４のようになる。また、図３、図４の（ａ）、（ｂ）は電源の極性が正極性（電源ＡＣのスイッチング素子Ｑ１、Ｑ２の接続点側が負極）のとき、及び負極性（電源ＡＣのスイッチング素子Ｑ１、Ｑ２の接続点側が正極）のときに、それぞれ対応する。
【００１２】
図４に示す定常時の駆動方法は、スイッチング素子Ｑ１及びＱ２に流れる電流を少なくする方法の１つであるが、図４に示すように、Ｔ２の期間に負荷回路（この場合、ランプとコンデンサＣ２の並列回路）とインダクタＬ２の直列回路をスイッチング素子Ｑ１とＱ３又はＱ２とＱ４によって短絡する状態が生ずる。これは、負荷回路とインダクタＬ２の直列回路にＴ１の期間に、平滑コンデンサＣ１のエネルギーを供給するが、無負荷状態であると、直ちに充電は終了し、平滑コンデンサＣ１の電圧とほぼ同じ電圧が負荷回路のコンデンサＣ２に充電された後、前述のごとく負荷回路をＴ２の期間は短絡することになるので、コンデンサＣ２のエネルギーをインダクタＬ２に供給し、それをＴ３の期間以降で平滑コンデンサＣ１に還流して戻してしまうことになる。すなわち、コンデンサＣ２の電圧は平滑コンデンサＣ１の電圧に比べて低くなってしまう。また、この動作のみにおいてもＴ２の期間、電源電圧を昇圧し、平滑コンデンサＣ１の電圧を高くする作用は一応あるが、コンデンサＣ２の電圧はどうしても小さくなってしまう。
【００１３】
そこで、本実施例では、不点灯時では、入力電圧極性が反転して所定時間、図３に示す駆動方法による昇圧動作を行うことにより、平滑コンデンサＣ１の電圧を入力電圧より十分に昇圧し、コンデンサＣ２には点灯するのに必要な電圧を得ようとするものである。すなわち、この構成は入力電源電圧Ｖａｃのピーク値よりもコンデンサＣ１の電圧Ｖｃ１が高く、コンデンサＣ１の電圧はコンデンサＣ２の電圧Ｖｃ２よりも高い場合に有効である。負荷電圧は図５のようになる。
【００１４】
また、本実施例では電源極性の反転直後にのみ昇圧動作を行うように構成しているが、この部分のみならず、商用周期の間のいかなる所で行うようにしても良いし、入力電源ＡＣとインダクタＬ１の直列回路を短絡する動作が含まれている、いかなるスイッチング方法でも、略無負荷状態において動作する場合には本発明を適用できる。以上のように構成することにより、電源電圧が低くても十分な始動電圧が得られるものである。
【００１５】
（実施例２）
図６は第２の実施例の回路図である。インバータ回路を含む主回路の構成については、図１に示した第１の実施例と同様である。ただし、本実施例では、主回路に電源の極性を検出する極性判別回路１と、負荷であるランプが点灯しているか否かを検出する点灯判別回路２のほかに、平滑コンデンサＣ１の電圧を検出するコンデンサ電圧検出回路５が新たに付加されている。極性切り替え回路４ａは、電源ＡＣの極性にしたがって、駆動回路の出力を切り替え、電源ＡＣと同期した電圧を負荷に印加するように動作する。発振回路６は、スイッチング素子Ｑ１〜Ｑ４に印加する高周波信号（図７参照）を発生させる。この発振回路６は、極性切り替え回路４と共に、電源の極性が正極性（電源ＡＣのスイッチング素子Ｑ１、Ｑ２の接続点側が負極）のときは、図７（ａ）の駆動信号波形を発生させ、電源の極性が負極性（電源ＡＣのスイッチング素子Ｑ１、Ｑ２の接続点側が正極）のときは、図７（ｂ）の駆動信号波形を発生させる。これらの駆動信号波形において、Ｔ１の期間は固定されており、Ｔ２の期間がＰＷＭ変調されるように動作する。そのＰＷＭ変調は平滑コンデンサＣ１の電圧の検出値と基準電圧ｅ１あるいはｅ２を比較して、コンデンサＣ１の検出値と基準電圧ｅ１あるいはｅ２が等しくなるように動作する。すなわち、Ｔ２の期間を変化させ、入力電源ＡＣより流入するエネルギーの量を調節することにより、コンデンサＣ１の電圧を基準電圧ｅ１あるいはｅ２に応じた電圧に一致せしめるように動作する。
【００１６】
また、基準電圧ｅ１とｅ２は点灯判別回路２の出力により切り替えられ、ｅ２＞ｅ１であるとすると、ランプの不点灯時には高い方の基準電圧ｅ２に切り替えられ、点灯時には低い方の基準電圧ｅ１に切り替えるように構成する。これは、不点灯時の平滑コンデンサＣ１の電圧は、点灯時の平滑コンデンサＣ１の電圧より高くなることを意味している。なぜならば、図７のＴ２の期間のような電源電圧を昇圧し平滑コンデンサＣ１に蓄積する動作を行う場合、どうしても負荷とインダクタＬ２の直列回路を短絡してしまうので、平滑コンデンサＣ１に比べてコンデンサＣ２の電圧は低くなる傾向がある。そこで、平滑コンデンサＣ１の電圧を予め高く設定するのである。すなわち、この構成は入力電源電圧Ｖａｃのピーク値よりもコンデンサＣ１の電圧Ｖｃ１が高く、コンデンサＣ１の電圧はコンデンサＣ２の電圧Ｖｃ２よりも高い場合に有効である。
【００１７】
以上のように構成することにより、電源電圧が低くとも、負荷として高圧放電灯を使用しそれを点灯させる場合に、前述のごとく放電開始までの間、ランプに始動に十分な電圧を供給するとともに、点灯時は平滑コンデンサＣ１の電圧を低く抑え、スイッチング素子の損失を低くし、回路を小型化することが可能である。
【００１８】
また、本実施例では毎スイッチング周期に昇圧の動作を挿入し、平滑コンデンサＣ１の電圧を切り替えるように構成しているが、切り替えはいかなる検出手段によって行われても良く、電源とインダクタＬ１の直列回路を短絡する動作が含まれているスイッチング方法であれば、いかなるスイッチング方法でも略無負荷状態において動作するものには本発明を適用できる。
【００１９】
（実施例３）
図８は第３の実施例の回路図である。この回路においても主回路の構成は前述の各実施例と同様である。制御回路の構成については、本実施例では、発振回路Ａと発振回路Ｂの２つの回路を備え、それらは点灯判別回路２の出力により切り替えられる。負荷として高圧放電灯を用いた際の不点灯時には、図９に示すような駆動信号の発生を行い、点灯時には図１０に示すような駆動信号の発生を行う。図９、図１０の（ａ）、（ｂ）は電源の極性が正極性（電源ＡＣのスイッチング素子Ｑ１、Ｑ２の接続点側が負極）のとき、及び負極性（電源ＡＣのスイッチング素子Ｑ１、Ｑ２の接続点側が正極）のときに、それぞれ対応する。
【００２０】
このスイッチング動作は無負荷時において、負荷回路とインダクタＬ２の直列回路をＴ２の期間に短絡し、コンデンサＣ２のエネルギーをインダクタＬ２に蓄積して、コンデンサＣ２のエネルギーを平滑コンデンサＣ１に戻す動作を行うものである。これは、前述の実施例１、２と異なり、無負荷時には電源電圧を昇圧することなく、コンデンサＣ２の電圧が平滑コンデンサＣ１よりも低くなるように動作している。このように構成することにより、電源電圧が高い場合、たとえば、海外などの２８８Ｖ電源（最大値は４００Ｖ程度）に対応した装置を作成したときに不必要に負荷に高い電圧を印加しないようにすることができる。（たとえば３００Ｖぐらいにできる。）これにより、負荷回路の素子の耐圧などを低く抑えることができ、装置の小型化や、コストダウンに寄与することができる。この構成においては、スイッチング素子の駆動方法の一例を示しているが、これに限定されるものではない。
【００２１】
（実施例４）
図１１は第４の実施例の回路図である。本実施例の回路図は図８と同じである。制御回路の構成については、本実施例では、発振回路Ａと発振回路Ｂの２つの回路を備え、それらは点灯判別回路２の出力により切り替えられる。負荷として高圧放電灯を用いた際の不点灯時には、図１２に示すような駆動信号の発生を行い、点灯時には図１３に示すような駆動信号の発生を行う。図１２、図１３の（ａ）、（ｂ）は電源の極性が正極性（電源ＡＣのスイッチング素子Ｑ１、Ｑ２の接続点側が負極）のとき、及び負極性（電源ＡＣのスイッチング素子Ｑ１、Ｑ２の接続点側が正極）のときに、それぞれ対応する。
【００２２】
このスイッチング素子の動作は、無負荷時において、負荷回路とインダクタＬ２の直列回路に平滑コンデンサＣ１のエネルギーを供給する動作のみを行うもので、電源電圧に対して平滑コンデンサＣ１の電圧を昇圧することはなく、電源のピーク電圧をそのまま、平滑コンデンサＣ１に充電し、負荷に印加するものである。これは、前述の実施例１、２、３と異なり、無負荷時には電源電圧を昇圧することなく、また、平滑コンデンサＣ１に対して降圧動作をすることもなく、電源電圧の最大値が負荷に印加されるように動作するものである。このように構成することにより、電源電圧の最大値が無負荷時の印加電圧と略等しい場合、例えば、２００Ｖ電源（最大値は２８０Ｖ程度）に対応した装置を作成したときに、不必要に負荷に高い電圧を印加しないようにすることができる。よって、始動時の動作を簡単にすることができ、回路の低コスト化に寄与することができる。この構成においては、点灯時のスイッチング素子の駆動法の一例とともに、不点灯時には切り替えることを示しているが、点灯時の動作を規定しているのではなく、無負荷時に平滑コンデンサＣ１の電圧を負荷回路とコンデンサＣ２の直列回路に印加する動作のみであることを示しており、これに限定されるものではない。
【００２３】
（実施例５）
図１４は第５の実施例の回路図である。主回路の構成などは前述のものに準ずるので省略する。点灯判別回路２は、ランプが点灯しているか否かを検出し、不点灯時には信号を出力する。タイマー回路３’は点灯判別回路２からの入力信号があったとき（不点灯時）に、極性判別回路１の出力を一定時間Δｔ’遅らせて出力する。点灯判別回路２からの入力信号が無いとき（点灯時）には、タイマー回路３は極性判別回路１の出力をそのまま出力する。図１５（ａ）に不点灯時の信号波形を、図１５（ｂ）に点灯時の信号波形を示す。
【００２４】
発振回路Ａ、Ｂではそれぞれ、不点灯時と点灯時に対応した図１７、図１８に示す駆動波形が出力されるように動作する。図１７に示す波形は実施例４に示すもので、平滑コンデンサＣ１の電圧と略等しい電圧が出力される動作で、タイマー回路７の作用により通常と逆極性の場合、たとえば電源が正極性のときに、（ｂ）の動作をした場合には負荷には通常と同じであるが、電源に対しては昇圧動作を行うものになる。すなわち、平滑コンデンサＣ１の電圧に略等しい電圧をコンデンサＣ２に印加しつつ、電源電圧を昇圧して平滑コンデンサＣ１の電圧を高くすることが可能となるのである。但し、副作用として、スイッチング素子に入力側の電流と負荷側の電流が同じ向きに重なって流れて損失が増えることが考えられるが、これは、不点灯時の無負荷状態の動作であるため、負荷側の電流はほとんど流れない。したがって特に問題にはならない。
【００２５】
以上のように構成することにより、電源よりも無負荷時の印加電圧が高い場合においてもランプの始動に必要な電圧を供給することができる。なお、この構成においては、図１６に示すように、電源の周期と同じ周期で位相が遅れた形で負荷に電圧が供給されているが、これは位相が進んだ形でも良く、限定されるものではない。
【００２６】
（実施例６）
図１９は本発明の第６の実施例の出力波形を示している。この実施例は、第５の実施例を別の形にしたもので、負荷への出力電圧を入力電圧の周期よりも長くなるようにしたものである。この実施例においては、負荷に平滑コンデンサＣ１のエネルギーを供給する期間と、負荷に平滑コンデンサＣ１のエネルギーを供給しつつ、平滑コンデンサＣ１の電圧を昇圧する周期とが存在する。このように、無負荷状態においてのみ、動作の電源に対する極性をずらすことで電源電圧が低くとも、不点灯状態のランプに適切な電圧を印加することができる。
【００２７】
【発明の効果】
以上のように構成することにより、定常負荷時はスイッチング素子に逆向きに２つの電流ループの電流が流れて、損失を小さくしつつ、負荷が電力をほとんど消費しない略無負荷時には電源電圧に応じた動作をさせることで、必要な電圧を負荷に印加することができる。したがって、負荷に高圧放電灯を使用した場合に、定常点灯時にも不点灯時にも良好な動作を実現できる。
【図面の簡単な説明】
【図１】本発明の第１実施例の回路図である。
【図２】本発明の第１実施例の各部の動作を示す波形図である。
【図３】本発明の第１実施例の無負荷時のスイッチング動作を示す波形図である。
【図４】本発明の第１実施例の点灯時のスイッチング動作を示す波形図である。
【図５】本発明の第１実施例の入出力電圧を示す波形図である。
【図６】本発明の第２実施例の回路図である。
【図７】本発明の第２実施例のスイッチング動作を示す波形図である。
【図８】本発明の第３実施例の回路図である。
【図９】本発明の第３実施例の無負荷時のスイッチング動作を示す波形図である。
【図１０】本発明の第３実施例の点灯時のスイッチング動作を示す波形図である。
【図１１】本発明の第４実施例の回路図である。
【図１２】本発明の第４実施例の無負荷時のスイッチング動作を示す波形図である。
【図１３】本発明の第４実施例の点灯時のスイッチング動作を示す波形図である。
【図１４】本発明の第５実施例の回路図である。
【図１５】本発明の第５実施例の各部の動作を示す波形図である。
【図１６】本発明の第５実施例の入出力電圧を示す波形図である。
【図１７】本発明の第５実施例の無負荷時のスイッチング動作を示す波形図である。
【図１８】本発明の第５実施例の点灯時のスイッチング動作を示す波形図である。
【図１９】本発明の第６実施例の入出力電圧を示す波形図である。
【図２０】従来例の回路図である。
【図２１】従来例のスイッチング動作を示す波形図である。
【図２２】従来例の一方の電源極性時のスイッチング動作を示す回路図である。
【図２３】従来例の他方の電源極性時のスイッチング動作を示す回路図である。
【符号の説明】
Ｑ１〜Ｑ４スイッチング素子
Ｄ５、Ｄ６ダイオード
Ｃ１コンデンサ
Ｌ１第１のインダクタ
Ｌ２第２のインダクタ
ＡＣ交流電源
Ｌａｍｐ放電灯負荷[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power supply apparatus in which a switching circuit that performs a plurality of power conversions shares a switching element. More specifically, the input circuit from an AC power supply is improved by a chopper circuit and the load circuit is synchronized with the AC power supply. The present invention relates to a power supply device including an inverter circuit that supplies a low-frequency output.
[0002]
[Prior art]
FIG. 20 is a circuit diagram of a conventional power supply device. In this power supply device, a series circuit of switching elements Q1 and Q2, a series circuit of switching elements Q3 and Q4, and a series circuit of diodes D5 and D6 are connected in parallel between both ends of the electrolytic capacitor C. An inductor L2 and a load circuit Z are connected between the connection point of the switching elements Q1 and Q2 and the connection point of the switching elements Q3 and Q4, and the connection point A of the diodes D5 and D6 and the switching elements Q1 and Q2 are connected. The AC power supply AC and the inductor L1 are connected between these connection points. Each switching element Q1 to Q4 includes antiparallel diodes D1 to D4, respectively.
[0003]
First, an example of the operation of this circuit is shown below. When the connection point side of the diodes D1 and D2 of the input AC power supply is negative, the switching elements Q2 and Q3 are ON and the switching elements Q1 and Q4 are OFF as shown in FIG. )), Switching elements Q1 and Q3 are ON, switching elements Q2 and Q4 are OFF (see FIG. 22B), and all switching elements are OFF (see FIG. 22C) in order. Yes, it works to repeat them periodically.
[0004]
Further, when the connection point side of the diodes D1 and D2 of the input AC power supply is positive, as shown in FIG. 21B, the switching elements Q1 and Q4 are ON and the switching elements Q2 and Q3 are OFF (FIG. 23). (See (a)), a period in which switching elements Q2 and Q4 are ON, and switching elements Q1 and Q3 are OFF (see FIG. 23 (b)), and a period in which all switching elements are OFF (see FIG. 23 (c)). Operate in order to repeat them periodically. As the circuit operates as described above, a rectangular wave voltage synchronized with the input commercial frequency power supply AC is applied to the load Z.
[0005]
And, since the currents of the two loops simultaneously flow in the opposite directions to the switching elements Q1 and Q2 that are also used, the current flowing through the switching elements is substantially reduced, the loss of the switching elements is reduced, and heat is generated. Thus, a small-sized and low-cost power supply device is provided.
[0006]
[Problems to be solved by the invention]
In general, a high-pressure discharge lamp is in an extremely high impedance state (hereinafter referred to as “no-load state”) until discharge is started. To start the discharge lamp, in its no-load state, discharge is started by superimposing a high-voltage pulse voltage on the lamp applied voltage. Immediately after the start of discharge, the temperature in the tube is low, so the pressure in the tube is low and the impedance is very low (several ohms) (ie low lamp voltage state). By maintaining the discharge state, the pressure increases as the temperature rises. It becomes higher, the electrical impedance rises, and it shifts to a stable lighting state. As described above, in order to stably start and light the high pressure discharge lamp, it is necessary to create a state in which a voltage of about 200 V to 400 V is applied when the high pressure pulse is applied. Further, in the high pressure discharge lamp, it is necessary to connect a capacitor in parallel to stabilize the discharge and to bypass the high frequency component of the current so that the high frequency current does not flow through the discharge lamp. This is because no acoustic resonance phenomenon occurs.
[0007]
In the conventional example, the operation at the start when the high pressure discharge lamp is used as a load as described above is not considered, and the power supply voltage and the voltage applied to the load are not considered. Therefore, the present invention intends to propose an operation or the like when a high pressure discharge lamp is used as a load.
[0008]
[Means for Solving the Problems]
According to the present invention, in order to solve the above-described problem, at least one boost chopper circuit including at least one switching element that receives an AC power supply and at least one first inductor;
Including at least one second inductor and a load circuit, and including at least one step-down chopper circuit connected to the step-up chopper circuit via a smoothing capacitor;
At least one switching element of the step-up chopper circuit and the switching element of the step-down chopper circuit are combined, and at least a period during which the current during the step-up operation and the current during the step-down operation flow in a direction canceling each other out to the switching element that is also used In a power supply apparatus that includes a control circuit that operates so as to occur, and that applies an alternating voltage synchronized with an input alternating voltage to a load,
When the load resistance is higher than normal and there is almost no load (the load consumes little power), both ends of the series circuit of the input power supply and the first inductor are short-circuited, and the energy of the input power supply is reduced to the first inductor. The switching operation is performed in a cycle including a period in which the energy accumulated in the first inductor is discharged to the smoothing capacitor through the input power supply after the period in which the first inductor is accumulated.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Example 1
FIG. 1 is a circuit diagram of a first embodiment of the present invention. This circuit is composed of an inverter circuit portion and a control circuit portion. The inverter circuit includes a step-up chopper circuit for improving input current distortion by switching elements Q1 and Q2, an inductor L1, and diodes D5 and D6, and a step-down chopper circuit for load current limiting by switching elements Q1 to Q4 and an inductor L2. I have. The circuit configuration will be described below. A series circuit of switching elements Q1 and Q2, a series circuit of switching elements Q3 and Q4, and a series circuit of diodes D5 and D6 are connected in parallel with the smoothing capacitor C1. A parallel circuit of the discharge lamp Lamp and the capacitor C2 is connected via an inductor L2 between the connection point of the switching elements Q1, Q2 and the connection point of the switching elements Q3, Q4. An AC power supply AC and an inductor L1 are connected in a series circuit between the connection point of the diodes D5 and D6 and the connection point of the switching elements Q1 and Q2.
[0010]
The polarity discrimination circuit 1 detects the polarity of the input power supply AC and outputs a signal corresponding to the polarity. The lighting determination circuit 2 detects whether or not the lamp is lit, and outputs a signal when the lamp is not lit. The timer circuit 3 outputs a timer signal for a period of Δt from the time when the voltage of the input power supply AC crosses zero when the input signal from the lighting determination circuit 2 (when not lighting), and the input from the lighting determination circuit 2 When there is no signal (when lit), nothing is output. FIG. 2A shows a signal waveform when not lit, and FIG. 2B shows a signal waveform when lit.
[0011]
The oscillation circuit A generates a signal (see FIG. 3) that serves as a reference for a drive signal during a boosting operation, and the oscillation circuit B generates a signal (see FIG. 4) that serves as a reference for a drive signal during steady operation. It is. The signal switching circuit 4 switches the operation polarity of the switching element according to the polarity of the power source AC, and inserts a period for performing the boosting operation for Δt from the time when the polarity of the power source AC is changed when the light source is not turned on. Thereafter, the operation is performed so as to switch to the driving signal at the normal time. As a result, the drive waveforms of the switching elements Q1 to Q4 are as shown in FIG. 3 at the time of boosting, and the drive waveforms at the steady state are as shown in FIG. 3A, 3B and 4B, when the polarity of the power supply is positive (the connection point side of the switching elements Q1 and Q2 of the power supply AC is negative), and when the polarity is negative (the switching element Q1 of the power supply AC). , Q2 is connected to the positive electrode).
[0012]
The steady-state driving method shown in FIG. 4 is one of the methods for reducing the current flowing through the switching elements Q1 and Q2, but as shown in FIG. 4, the load circuit (in this case, a lamp and a capacitor is used during the period T2. C2) and the series circuit of the inductor L2 are short-circuited by the switching elements Q1 and Q3 or Q2 and Q4. This is because the energy of the smoothing capacitor C1 is supplied to the series circuit of the load circuit and the inductor L2 during the period T1, but in the no-load state, the charging is immediately terminated and a voltage almost equal to the voltage of the smoothing capacitor C1 is obtained. After the capacitor C2 of the load circuit is charged, the load circuit is short-circuited during the period T2, as described above. Therefore, the energy of the capacitor C2 is supplied to the inductor L2, and is supplied to the smoothing capacitor C1 after the period T3. It will return to reflux. That is, the voltage of the capacitor C2 becomes lower than the voltage of the smoothing capacitor C1. In this operation alone, the power supply voltage is boosted and the voltage of the smoothing capacitor C1 is increased during the period T2, but the voltage of the capacitor C2 is inevitably reduced.
[0013]
Therefore, in this embodiment, when the light is not lit, the voltage of the smoothing capacitor C1 is sufficiently boosted from the input voltage by performing the boosting operation by the driving method shown in FIG. The capacitor C2 is intended to obtain a voltage necessary for lighting. That is, this configuration is effective when the voltage Vc1 of the capacitor C1 is higher than the peak value of the input power supply voltage Vac and the voltage of the capacitor C1 is higher than the voltage Vc2 of the capacitor C2. The load voltage is as shown in FIG.
[0014]
Further, in this embodiment, the boosting operation is performed only immediately after the inversion of the power supply polarity. However, this operation may be performed not only in this part but also anywhere in the commercial cycle, or the input power supply AC The present invention can be applied to any switching method including an operation of short-circuiting the series circuit of the inductor L1 and the inductor L1 when operating in a substantially no-load state. By configuring as described above, a sufficient starting voltage can be obtained even when the power supply voltage is low.
[0015]
(Example 2)
FIG. 6 is a circuit diagram of the second embodiment. The configuration of the main circuit including the inverter circuit is the same as that of the first embodiment shown in FIG. However, in this embodiment, the voltage of the smoothing capacitor C1 is applied in addition to the polarity discrimination circuit 1 for detecting the polarity of the power source in the main circuit and the lighting discrimination circuit 2 for detecting whether or not the lamp as the load is lit. A capacitor voltage detection circuit 5 for detection is newly added. The polarity switching circuit 4a operates so as to switch the output of the drive circuit according to the polarity of the power supply AC and to apply a voltage synchronized with the power supply AC to the load. The oscillation circuit 6 generates a high frequency signal (see FIG. 7) to be applied to the switching elements Q1 to Q4. This oscillation circuit 6 generates the drive signal waveform of FIG. 7A together with the polarity switching circuit 4 when the polarity of the power supply is positive (the connection point side of the switching elements Q1 and Q2 of the power supply AC is negative) When the polarity of the power supply is negative (the connection point side of the switching elements Q1 and Q2 of the power supply AC is positive), the drive signal waveform shown in FIG. 7B is generated. In these drive signal waveforms, the period of T1 is fixed, and the period of T2 operates so as to be PWM-modulated. The PWM modulation compares the detected value of the voltage of the smoothing capacitor C1 with the reference voltage e1 or e2, and operates so that the detected value of the capacitor C1 is equal to the reference voltage e1 or e2. That is, by changing the period of T2 and adjusting the amount of energy flowing from the input power supply AC, the voltage of the capacitor C1 operates to match the voltage according to the reference voltage e1 or e2.
[0016]
Further, the reference voltages e1 and e2 are switched by the output of the lighting discrimination circuit 2. If e2> e1, the reference voltage e1 is switched to the higher reference voltage e2 when the lamp is not lit, and is switched to the lower reference voltage e1 when lit. Configure to switch. This means that the voltage of the smoothing capacitor C1 when not lit is higher than the voltage of the smoothing capacitor C1 when lit. This is because when the operation of boosting the power supply voltage during the period T2 in FIG. 7 and storing it in the smoothing capacitor C1 is performed, the series circuit of the load and the inductor L2 is inevitably short-circuited. The voltage of C2 tends to be low. Therefore, the voltage of the smoothing capacitor C1 is set high beforehand. That is, this configuration is effective when the voltage Vc1 of the capacitor C1 is higher than the peak value of the input power supply voltage Vac and the voltage of the capacitor C1 is higher than the voltage Vc2 of the capacitor C2.
[0017]
By configuring as described above, even when the power supply voltage is low, when a high pressure discharge lamp is used as a load and it is lit, a sufficient voltage for starting is supplied to the lamp until the start of discharge as described above. During lighting, the voltage of the smoothing capacitor C1 can be kept low, the loss of the switching element can be reduced, and the circuit can be miniaturized.
[0018]
Further, in this embodiment, a boosting operation is inserted in each switching cycle and the voltage of the smoothing capacitor C1 is switched. However, the switching may be performed by any detection means, and the power source and the inductor L1 are connected in series. As long as the switching method includes an operation of short-circuiting the circuit, the present invention can be applied to any switching method that operates in a substantially no-load state.
[0019]
Example 3
FIG. 8 is a circuit diagram of the third embodiment. Also in this circuit, the configuration of the main circuit is the same as that in each of the embodiments described above. With regard to the configuration of the control circuit, in this embodiment, two circuits of an oscillation circuit A and an oscillation circuit B are provided, and they are switched by the output of the lighting determination circuit 2. When the high pressure discharge lamp is not used as a load, a drive signal is generated as shown in FIG. 9 when not lit, and a drive signal as shown in FIG. 10 is generated when lit. 9A and 9B, the polarity of the power source is positive (the connection point side of the switching elements Q1 and Q2 of the power source AC is negative), and the negative polarity (the switching elements Q1 and Q2 of the power source AC). This corresponds to the case where the connection point side is positive).
[0020]
In this switching operation, when there is no load, the series circuit of the load circuit and the inductor L2 is short-circuited during the period T2, the energy of the capacitor C2 is accumulated in the inductor L2, and the energy of the capacitor C2 is returned to the smoothing capacitor C1. Is. Unlike the first and second embodiments described above, the voltage of the capacitor C2 operates so as to be lower than that of the smoothing capacitor C1 without increasing the power supply voltage when there is no load. With this configuration, when the power supply voltage is high, for example, when a device compatible with a 288V power supply (maximum value is about 400V) in overseas is created, a high voltage is not unnecessarily applied to the load. be able to. (For example, it can be set to about 300 V.) Thereby, the withstand voltage of the elements of the load circuit can be kept low, which can contribute to downsizing of the device and cost reduction. In this configuration, an example of a switching element driving method is shown, but the present invention is not limited to this.
[0021]
(Example 4)
FIG. 11 is a circuit diagram of the fourth embodiment. The circuit diagram of this embodiment is the same as FIG. With regard to the configuration of the control circuit, in this embodiment, two circuits of an oscillation circuit A and an oscillation circuit B are provided, and they are switched by the output of the lighting determination circuit 2. When the high pressure discharge lamp is not used as a load, the driving signal is generated as shown in FIG. 12 when the lamp is not lit, and the driving signal as shown in FIG. 13 is generated when the lamp is lit. 12A and 12B, when the polarity of the power supply is positive (the connection point side of the switching elements Q1 and Q2 of the power supply AC is negative), and when the polarity is negative (the switching elements Q1 and Q2 of the power supply AC). This corresponds to the case where the connection point side is positive).
[0022]
The operation of this switching element is to perform only the operation of supplying the energy of the smoothing capacitor C1 to the series circuit of the load circuit and the inductor L2 when there is no load, and boosts the voltage of the smoothing capacitor C1 with respect to the power supply voltage. Rather, the smoothing capacitor C1 is charged as it is with the peak voltage of the power supply and applied to the load. Unlike the first, second, and third embodiments described above, the maximum value of the power supply voltage is applied to the load without increasing the power supply voltage when there is no load and without performing a step-down operation on the smoothing capacitor C1. It operates to be applied. With this configuration, when the maximum value of the power supply voltage is substantially equal to the applied voltage at no load, for example, when a device corresponding to a 200 V power supply (maximum value is about 280 V) is created, the load is unnecessarily increased. It is possible to prevent a high voltage from being applied. Therefore, the operation at the time of starting can be simplified, which can contribute to the cost reduction of the circuit. In this configuration, together with an example of a driving method of the switching element at the time of lighting, the switching at the time of non-lighting is shown. However, the operation at the time of lighting is not regulated, and the voltage of the smoothing capacitor C1 is set at no load. This indicates that the operation is only applied to the series circuit of the load circuit and the capacitor C2, and the present invention is not limited to this.
[0023]
(Example 5)
FIG. 14 is a circuit diagram of the fifth embodiment. The configuration of the main circuit is the same as that described above, and is omitted. The lighting determination circuit 2 detects whether or not the lamp is lit, and outputs a signal when the lamp is not lit. When there is an input signal from the lighting determination circuit 2 (when it is not lit), the timer circuit 3 ′ delays the output of the polarity determination circuit 1 by a predetermined time Δt ′ and outputs it. When there is no input signal from the lighting determination circuit 2 (when lighting), the timer circuit 3 outputs the output of the polarity determination circuit 1 as it is. FIG. 15A shows a signal waveform when not lit, and FIG. 15B shows a signal waveform when lit.
[0024]
The oscillation circuits A and B operate so as to output the drive waveforms shown in FIGS. 17 and 18 corresponding to non-lighting and lighting, respectively. The waveform shown in FIG. 17 is the same as that shown in the fourth embodiment, and is an operation in which a voltage substantially equal to the voltage of the smoothing capacitor C1 is output. In addition, when the operation of (b) is performed, the load is the same as a normal load, but a boost operation is performed on the power supply. That is, the voltage of the smoothing capacitor C1 can be increased by boosting the power supply voltage while applying a voltage substantially equal to the voltage of the smoothing capacitor C1 to the capacitor C2. However, as a side effect, it is considered that the current on the input side and the current on the load side overlap the switching element in the same direction and increase the loss, but this is an operation in a no-load state when not lit, Almost no current on the load side flows. Therefore, it is not a problem.
[0025]
By configuring as described above, it is possible to supply a voltage necessary for starting the lamp even when the applied voltage at no load is higher than that of the power source. In this configuration, as shown in FIG. 16, the voltage is supplied to the load in a phase delayed by the same cycle as the power supply cycle, but this may be a phase advanced phase and is limited. It is not a thing.
[0026]
(Example 6)
FIG. 19 shows the output waveform of the sixth embodiment of the present invention. This embodiment is another embodiment of the fifth embodiment, in which the output voltage to the load is made longer than the cycle of the input voltage. In this embodiment, there are a period in which the energy of the smoothing capacitor C1 is supplied to the load and a period in which the voltage of the smoothing capacitor C1 is boosted while supplying the energy of the smoothing capacitor C1 to the load. In this way, only in the no-load state, by shifting the polarity with respect to the power supply for operation, an appropriate voltage can be applied to the lamp that is not lit even if the power supply voltage is low.
[0027]
【The invention's effect】
By configuring as described above, the current of the two current loops flows in the switching element in the opposite direction at the time of steady load, reducing the loss and responding to the power supply voltage at almost no load when the load consumes little power. By performing the above operation, a necessary voltage can be applied to the load. Therefore, when a high-pressure discharge lamp is used as a load, a good operation can be realized both at the time of steady lighting and at the time of non-lighting.
[Brief description of the drawings]
FIG. 1 is a circuit diagram of a first embodiment of the present invention.
FIG. 2 is a waveform diagram showing the operation of each part of the first embodiment of the present invention.
FIG. 3 is a waveform diagram showing a switching operation at no load according to the first embodiment of the present invention.
FIG. 4 is a waveform diagram showing a switching operation during lighting according to the first embodiment of the present invention.
FIG. 5 is a waveform diagram showing input / output voltages of the first embodiment of the present invention.
FIG. 6 is a circuit diagram of a second embodiment of the present invention.
FIG. 7 is a waveform diagram showing a switching operation of the second embodiment of the present invention.
FIG. 8 is a circuit diagram of a third embodiment of the present invention.
FIG. 9 is a waveform diagram showing a switching operation at no load according to the third embodiment of the present invention.
FIG. 10 is a waveform diagram showing a switching operation during lighting according to the third embodiment of the present invention.
FIG. 11 is a circuit diagram of a fourth embodiment of the present invention.
FIG. 12 is a waveform diagram showing a switching operation at the time of no load according to the fourth embodiment of the present invention.
FIG. 13 is a waveform diagram showing a switching operation during lighting according to a fourth embodiment of the present invention.
FIG. 14 is a circuit diagram of a fifth embodiment of the present invention.
FIG. 15 is a waveform chart showing the operation of each part of the fifth embodiment of the present invention.
FIG. 16 is a waveform diagram showing input / output voltages of a fifth embodiment of the present invention.
FIG. 17 is a waveform diagram showing a switching operation at the time of no load according to the fifth embodiment of the present invention.
FIG. 18 is a waveform diagram showing a switching operation during lighting according to a fifth embodiment of the present invention.
FIG. 19 is a waveform diagram showing input / output voltages of a sixth embodiment of the present invention.
FIG. 20 is a circuit diagram of a conventional example.
FIG. 21 is a waveform diagram showing a conventional switching operation.
FIG. 22 is a circuit diagram showing a switching operation in one power supply polarity in the conventional example.
FIG. 23 is a circuit diagram showing a switching operation in the other power source polarity of the conventional example.
[Explanation of symbols]
Q1 to Q4 Switching elements D5 and D6 Diode C1 Capacitor L1 First inductor L2 Second inductor AC AC power supply Lamp Discharge lamp load

Claims

At least one step-up chopper circuit input with an AC power supply and including at least one switching element and at least one first inductor;
Including at least one second inductor and a load circuit, and including at least one step-down chopper circuit connected to the step-up chopper circuit via a smoothing capacitor;
At least one switching element of the step-up chopper circuit and the switching element of the step-down chopper circuit are combined, and at least a period during which the current during the step-up operation and the current during the step-down operation flow in a direction canceling each other out to the switching element that is also used In a power supply apparatus that includes a control circuit that operates so as to occur, and that applies an alternating voltage synchronized with an input alternating voltage to a load,
At the time of substantially no load having a load resistance higher than that of the steady state, both ends of the series circuit of the input power source and the first inductor are short-circuited, and after the period in which the energy of the input power source is accumulated in the first inductor, the first inductor A power supply device that performs a switching operation in a cycle including a period in which the energy stored in is discharged to a smoothing capacitor through an input power supply.

At least one step-up chopper circuit input with an AC power supply and including at least one switching element and at least one first inductor;
Including at least one second inductor and a load circuit, and including at least one step-down chopper circuit connected to the step-up chopper circuit via a smoothing capacitor;
At least one switching element of the step-up chopper circuit and the switching element of the step-down chopper circuit are combined, and at least a period during which the current during the step-up operation and the current during the step-down operation flow in a direction canceling each other out to the switching element that is also used In a power supply apparatus that includes a control circuit that operates so as to occur, and that applies an alternating voltage synchronized with an input alternating voltage to a load,
When the load resistance is higher than normal and the load is almost unloaded, both ends of the series circuit of the load and the second inductor are short-circuited, and the energy of the load is stored in the second inductor, and then stored in the second inductor. The power supply device is characterized in that the switching operation is performed in a cycle including a period in which the released energy is discharged to the smoothing capacitor through the load.

At least one step-up chopper circuit input with an AC power supply and including at least one switching element and at least one first inductor;
Including at least one second inductor and a load circuit, and including at least one step-down chopper circuit connected to the step-up chopper circuit via a smoothing capacitor;
At least one switching element of the step-up chopper circuit and the switching element of the step-down chopper circuit are combined, and at least a period during which the current during the step-up operation and the current during the step-down operation flow in a direction canceling each other out to the switching element that is also used In a power supply apparatus that includes a control circuit that operates so as to occur, and that applies an alternating voltage synchronized with an input alternating voltage to a load,
At the time of substantially no load where the load resistance is higher than normal, both ends of the series circuit of the load and the second inductor are connected to a smoothing capacitor, and a current loop for supplying the energy of the smoothing capacitor to the series circuit is formed. After that, there is a period in which the current loop is opened so as not to supply energy to the series circuit, and the energy of the second inductor can be discharged, and only the two periods are formed periodically. A power supply device that performs a switching operation.

At least one step-up chopper circuit input with an AC power supply and including at least one switching element and at least one first inductor;
Including at least one second inductor and a load circuit, and including at least one step-down chopper circuit connected to the step-up chopper circuit via a smoothing capacitor;
At least one switching element of the step-up chopper circuit and the switching element of the step-down chopper circuit are combined, and at least a period during which the current during the step-up operation and the current during the step-down operation flow in a direction canceling each other out to the switching element that is also used In a power supply apparatus that includes a control circuit that operates so as to occur, and that applies an alternating voltage synchronized with an input alternating voltage to a load,
At the time of substantially no load where the load resistance is higher than normal, at least the combined switching element is turned ON to short-circuit the series circuit of the input power supply and the first inductor, and the energy of the input power supply is stored in the first inductor. The first current loop and the second current loop that accumulates in the second inductor while connecting the series circuit of the load circuit and the second inductor to the smoothing capacitor and supplying the energy of the smoothing capacitor to the load simultaneously Period to form,
A power supply device characterized in that only the period during which the combined switching element is turned off and the energy stored in the first and second inductors can be discharged to the smoothing capacitor is alternately included in the switching cycle. .

A circuit in which first and second switching elements each provided with reverse-direction energization elements in parallel are connected in series so that the forward direction is matched; and third and fourth switching elements each provided with reverse-direction energization elements in parallel Capacitors having the same polarity between a circuit connected in series so that the forward direction is matched and a circuit connected in series so that the forward direction is matched with the fifth and sixth switching elements each having reverse-direction energization elements in parallel And connected in series between an AC power source and a first inductor between a connection point of the first and second switching elements and a connection point of the fifth and sixth switching elements, A circuit configuration in which a series circuit of a load circuit and a second inductor is connected between a connection point of the first and second switching elements and a connection point of the third and fourth switching elements,
The first switching element and the second switching element are shared by the step-up chopper circuit and the step-down chopper circuit,
In a steady load, a control circuit is provided to operate the first and second switching elements that are used both for the current during the step-up operation and the current during the step-down operation so as to generate at least a period in which they flow in a mutually canceling direction. In a power supply device that applies an AC voltage synchronized with an input AC voltage,
At the time of substantially no load having a load resistance higher than that of the steady state, both ends of the series circuit of the input power source and the first inductor are short-circuited, and after the period in which the energy of the input power source is accumulated in the first inductor, the first inductor 2. The power supply device according to claim 1, wherein the switching operation is performed in a cycle including a period in which the energy stored in is discharged to the smoothing capacitor through the input power source.

A circuit in which first and second switching elements each provided with reverse-direction energization elements in parallel are connected in series so that the forward direction is matched; and third and fourth switching elements each provided with reverse-direction energization elements in parallel Capacitors having the same polarity between a circuit connected in series so that the forward direction is matched and a circuit connected in series so that the forward direction is matched with the fifth and sixth switching elements each having reverse-direction energization elements in parallel And connected in series between an AC power source and a first inductor between a connection point of the first and second switching elements and a connection point of the fifth and sixth switching elements, A circuit configuration in which a series circuit of a load circuit and a second inductor is connected between a connection point of the first and second switching elements and a connection point of the third and fourth switching elements,
The first switching element and the second switching element are shared by the step-up chopper circuit and the step-down chopper circuit,
In a steady load, a control circuit is provided to operate the first and second switching elements that are used both for the current during the step-up operation and the current during the step-down operation so as to generate at least a period in which they flow in a mutually canceling direction. In a power supply device that applies an AC voltage synchronized with an input AC voltage,
When the load resistance is higher than normal and the load is almost unloaded, both ends of the series circuit of the load and the second inductor are short-circuited, and the energy of the load is stored in the second inductor, and then stored in the second inductor. 3. The power supply device according to claim 2, wherein the switching operation is performed in a cycle including a period in which the released energy is discharged to the smoothing capacitor through the load.

A circuit in which first and second switching elements each provided with reverse-direction energization elements in parallel are connected in series so that the forward direction is matched; and third and fourth switching elements each provided with reverse-direction energization elements in parallel Capacitors having the same polarity between a circuit connected in series so that the forward direction is matched and a circuit connected in series so that the forward direction is matched with the fifth and sixth switching elements each having reverse-direction energization elements in parallel And connected in series between an AC power source and a first inductor between a connection point of the first and second switching elements and a connection point of the fifth and sixth switching elements, A circuit configuration in which a series circuit of a load circuit and a second inductor is connected between a connection point of the first and second switching elements and a connection point of the third and fourth switching elements,
The first switching element and the second switching element are shared by the step-up chopper circuit and the step-down chopper circuit,
In a steady load, a control circuit is provided to operate the first and second switching elements that are used both for the current during the step-up operation and the current during the step-down operation so as to generate at least a period in which they flow in a mutually canceling direction. In a power supply device that applies an AC voltage synchronized with an input AC voltage,
At the time of substantially no load where the load resistance is higher than normal, both ends of the series circuit of the load and the second inductor are connected to a smoothing capacitor, and a current loop for supplying the energy of the smoothing capacitor to the series circuit is formed. After that, there is a period in which the current loop is opened so as not to supply energy to the series circuit, and the energy of the second inductor can be discharged, and only the two periods are formed periodically. The power supply apparatus according to claim 3, wherein a switching operation is performed.

A circuit in which first and second switching elements each provided with reverse-direction energization elements in parallel are connected in series so that the forward direction is matched; and third and fourth switching elements each provided with reverse-direction energization elements in parallel Capacitors having the same polarity between a circuit connected in series so that the forward direction is matched and a circuit connected in series so that the forward direction is matched with the fifth and sixth switching elements each having reverse-direction energization elements in parallel And connected in series between an AC power source and a first inductor between a connection point of the first and second switching elements and a connection point of the fifth and sixth switching elements, A circuit configuration in which a series circuit of a load circuit and a second inductor is connected between a connection point of the first and second switching elements and a connection point of the third and fourth switching elements,
The first switching element and the second switching element are shared by the step-up chopper circuit and the step-down chopper circuit,
In a steady load, a control circuit is provided to operate the first and second switching elements that are used both for the current during the step-up operation and the current during the step-down operation so as to generate at least a period in which they flow in a mutually canceling direction. In a power supply device that applies an AC voltage synchronized with an input AC voltage,
When the load switching resistance is higher than that at the normal time, and when the first switching element or the second switching element, which is also used at least, is turned on, the series circuit of the input power supply and the first inductor is short-circuited. The first current loop for storing energy in the first inductor and the series circuit of the load circuit and the second inductor are connected to the smoothing capacitor, and the energy of the smoothing capacitor is supplied to the load while being stored in the second inductor. Forming a second current loop to be simultaneously formed;
The switching period is alternately included only in a period during which the combined switching element is turned off and the energy stored in the first and second inductors can be discharged to the smoothing capacitor. 4. The power supply device according to 4.

The power supply circuit configuration of claim 5 is provided, and at the time of steady load, by the action of the control circuit,
When the polarity on the connection point side of the rectifying element of the input AC power supply is positive, the first and second switching elements are turned on after the period in which the second and third switching elements are turned on and the first and fourth switching elements are turned off. 3 is provided with a period for turning on the switching elements 3 and turning off the second and fourth switching elements, and thereafter performing an operation of a switching cycle including at least a period for turning off all the switching elements,
When the polarity on the connection point side of the rectifying element of the input AC power source is negative, the second and second switching elements are turned on after the first and fourth switching elements are turned on and the second and third switching elements are turned off. The switching element 4 is turned on and a period for turning off the first and third switching elements is provided. After that, an operation of a switching cycle including at least a period for turning off all the switching elements is performed, and the first and second switching elements are operated. In the power supply device that operates to generate at least a period of flow in the direction of canceling each other, and applies an alternating voltage synchronized with the input alternating voltage to the load,
At almost no load, which has a higher load resistance than normal
When the polarity of the connection point side of the rectifying element of the input AC power supply is positive, the series circuit of the input power supply and the first inductor is short-circuited by turning on at least the first switching element that is also used as the input power supply. A period for forming a first current loop for storing energy in the first inductor;
When the polarity of the connection point side of the rectifying element of the input AC power supply is negative, the series circuit of the input power supply and the first inductor is short-circuited by turning on at least the second switching element that is also used as the input power supply. 6. The power supply device according to claim 5, wherein a periodic switching operation including at least a period for forming a first current loop for storing energy in the first inductor is performed.

The power supply circuit configuration of claim 6 is provided, and at the time of steady load, by the action of the control circuit,
When the polarity on the connection point side of the rectifying element of the input AC power supply is positive, the first and second switching elements are turned on after the period in which the second and third switching elements are turned on and the first and fourth switching elements are turned off. 3 is provided with a period for turning on the switching elements 3 and turning off the second and fourth switching elements, and thereafter performing an operation of a switching cycle including at least a period for turning off all the switching elements,
When the polarity on the connection point side of the rectifying element of the input AC power source is negative, the second and second switching elements are turned on after the first and fourth switching elements are turned on and the second and third switching elements are turned off. The switching element 4 is turned on and a period for turning off the first and third switching elements is provided. After that, an operation of a switching cycle including at least a period for turning off all the switching elements is performed, and the first and second switching elements are operated. In the power supply device that operates to generate at least a period of flow in the direction of canceling each other, and applies an alternating voltage synchronized with the input alternating voltage to the load,
At almost no load, which has a higher load resistance than normal
When the polarity on the connection point side of the rectifying element of the input AC power supply is positive, the series circuit of the load and the second inductor is short-circuited by turning on at least the fourth switching element, and the energy of the load is reduced to the second After a period for forming the first current loop accumulated in the inductor, a switching operation including at least a period for forming a second current loop for releasing the energy accumulated in the second inductor to the smoothing capacitor is performed.
When the polarity of the connection point side of the rectifying element of the input AC power source is negative, the series circuit of the load and the second inductor is short-circuited by turning on at least the third switching element, and the load energy is reduced to the second After the period of forming the first current loop accumulated in the inductor, the switching operation including at least the period of forming the second current loop for releasing the energy accumulated in the second inductor to the smoothing capacitor is performed. The power supply apparatus according to claim 6, wherein a periodic switching operation is performed.

The power supply circuit configuration according to claim 7, and at the time of steady load, by the action of the control circuit,
When the polarity on the connection point side of the rectifying element of the input AC power supply is positive, the first and second switching elements are turned on after the period in which the second and third switching elements are turned on and the first and fourth switching elements are turned off. 3 is provided with a period for turning on the switching elements 3 and turning off the second and fourth switching elements, and thereafter performing an operation of a switching cycle including at least a period for turning off all the switching elements,
When the polarity on the connection point side of the rectifying element of the input AC power source is negative, the second and second switching elements are turned on after the first and fourth switching elements are turned on and the second and third switching elements are turned off. The switching element 4 is turned on and a period for turning off the first and third switching elements is provided. After that, an operation of a switching cycle including at least a period for turning off all the switching elements is performed, and the first and second switching elements are operated. In the power supply device that operates to generate at least a period of flow in the direction of canceling each other, and applies an alternating voltage synchronized with the input alternating voltage to the load,
At almost no load, which has a higher load resistance than normal
When the polarity of the connection point side of the rectifying element of the input AC power supply is positive, the current that can supply the energy of the smoothing capacitor to the series circuit of the load and the second inductor by turning on the second and third switching elements After a period for forming a loop, a periodic switching operation constituted by a period in which all switching elements are turned off is performed.
When the polarity of the connection point side of the rectifying element of the input AC power supply is negative, the current that can supply the energy of the smoothing capacitor to the series circuit of the load and the second inductor by turning on the first and fourth switching elements 8. The power supply apparatus according to claim 7, wherein after the period for forming the loop, a periodic switching operation is performed that is constituted by a period in which all the switching elements are turned off.

The power supply circuit configuration of claim 8 is provided, and at the time of steady load, by the action of the control circuit,
When the polarity on the connection point side of the rectifying element of the input AC power supply is positive, the first and second switching elements are turned on after the period in which the second and third switching elements are turned on and the first and fourth switching elements are turned off. 3 is provided with a period for turning on the switching elements 3 and turning off the second and fourth switching elements, and thereafter performing an operation of a switching cycle including at least a period for turning off all the switching elements,
When the polarity on the connection point side of the rectifying element of the input AC power source is negative, the second and second switching elements are turned on after the first and fourth switching elements are turned on and the second and third switching elements are turned off. The switching element 4 is turned on and a period for turning off the first and third switching elements is provided. After that, an operation of a switching cycle including at least a period for turning off all the switching elements is performed, and the first and second switching elements are operated. In the power supply device that operates to generate at least a period of flow in the direction of canceling each other, and applies an alternating voltage synchronized with the input alternating voltage to the load,
At almost no load, which has a higher load resistance than normal
When the polarity of the connection point side of the rectifying element of the input AC power supply is positive, a current loop for storing the energy of the input power supply in the first inductor by turning on the first and fourth switching elements, a load, After a period in which two current loops that can supply the energy of the smoothing capacitor to the series circuit of the second inductor are simultaneously formed, a periodic switching operation configured by a period in which all the switching elements are turned off is performed.
When the polarity of the connection point side of the rectifying element of the input AC power supply is negative, a current loop that stores the energy of the input power supply in the first inductor by turning on the second and third switching elements, and a load After the period in which two current loops that can supply the energy of the smoothing capacitor to the series circuit of the second inductor are formed simultaneously, at least a periodic switching operation constituted by a period in which all the switching elements are turned off is performed. The power supply device according to claim 8, wherein:

The power supply device according to any one of claims 1 to 12, wherein a high-pressure discharge lamp is used as a load.