JP3630733B2

JP3630733B2 - Electronic lighting device for discharge lamp

Info

Publication number: JP3630733B2
Application number: JP25893094A
Authority: JP
Inventors: 正興関根
Original assignee: Origin Electric Co Ltd
Current assignee: Origin Electric Co Ltd
Priority date: 1994-09-28
Filing date: 1994-09-28
Publication date: 2005-03-23
Anticipated expiration: 2020-03-23
Also published as: JPH0896973A

Description

【０００１】
【産業上の利用分野】
この発明は交流電源から取り出す電流を正弦波状にするとともに、放電灯の電力制御を行い安定に点灯する放電灯用電子点灯装置に関する。
【０００２】
【従来の技術】
従来の放電灯用の点灯装置としては磁気漏れトランスによるものがほとんどで、電力制御は行われず、入力電圧が変動すると放電灯の消費電力も変動し、明るさが変わったり、放電灯寿命に影響するなどの問題があるとともに、図９に示すように商用電圧の電圧変化に応じて放電灯の消費電力も変化するため輝度リプルが生じ、投影装置に使用した場合、ちらつきがあり映像が見にくいという問題があった。磁気漏れトランス方式は上述の問題のほかに、大きくかつ重く、持ち運びが不便なため、近年、高速スイッチング素子を使用した高周波変調方式による電子式点灯装置が利用され始めてきた。
【０００３】
従来の放電灯用電子点灯装置の一例を図１０に示す。この回路では交流電圧を整流回路２１で整流し、入力電圧が１００Ｖ系の時はＳＷ１を閉じて倍電圧整流、２００Ｖ系の時はＳＷ１を開いて全波整流とし、直流の２７０〜３３０Ｖ程度の電圧を得て、降圧チョッパ回路２２で放電灯に必要な電圧に変換する。変換された直流電圧をブリッジ回路２３のスイッチ素子Ｑ２，Ｑ５とＱ３，Ｑ４の導通を切り替えて矩形波の交流電圧を発生させ，放電灯に供給する。降圧チョッパ回路２２を高周波で動作させることにより、小形軽量の安定器を実現できる。
【０００４】
【発明が解決しようとする課題】
しかしこのような従来の放電灯用電子点灯装置においては、その入力電流が交流周期の一部の電気角度のみ流れる波形で、多くの高調波電流を配電系統に流すため受・配電容量の増加や高調波障害の原因となった。また近く実施される予定の高調波規制を満足できず、実際上大きな問題となる。高調波規制を満足するには前段に昇圧チョッパなどの高調波抑制手段を使用しなければならないが、そうすると昇圧チョッパと降圧チョッパの双方が必要となり、高価になるとともに大型化するという問題がある。
【０００５】
この発明はこのような問題点に着目し、放電灯用電子点灯装置において、入力電流を正弦波状にして高調波を低減すると同時に、負荷である放電灯にちらつきのない安定した輝度を発生させることを課題とする。
【０００６】
【課題を解決するための手段】
この発明はこの課題を解決するため、昇降圧チョッパ回路で高調波を抑制しながら出力に定電力を供給し、負荷である放電灯にちらつきのない低周波交流の定電力を供給するように制御するものである。まず第１の基本的な手段として、以下の手段を提案する。商用交流電源に接続される一対の入力端子と、この一対の入力端子に接続され脈流に変換する整流回路と、この整流回路の脈流出力に接続される昇降圧形コンバータ回路であって、この脈流の周波数に比較して十分高い周波数でスイッチングするスイッチング素子と、昇降圧用インダクタンス手段と、整流回路とからなり、前記スイッチング素子のオン期間に前記昇降圧用インダクタンス手段に溜まったエネルギーをすべてオフ期間に出力側へ放出する昇降圧形コンバータ回路と、前記昇降圧形コンバータ回路のスイッチング素子を固定周波数で動作させると共に、前記商用交流電圧の少なくとも１サイクルの期間は固定時比率で動作させ、前記昇降圧形コンバータ回路の入力電圧の平均値に反比例するように前記スイッチング素子の時比率制御を行い、前記昇降圧形コンバータ回路の出力を一定電力に保つように制御する演算制御回路と、前記昇降圧形コンバータ回路の出力に接続されて一定周波数の交番電圧に変換するインバータ回路と、このインバータ回路の出力に接続され、放電灯に電力供給する一対の出力端子と、からなる放電灯用電子点灯装置を提案するものである。
【０００７】
第２の手段として、商用交流電源に接続される一対の入力端子と、この一対の入力端子に接続され脈流に変換する整流回路と、この整流回路の脈流出力に接続される昇降圧形コンバータ回路であって、この脈流の周波数に比較して十分高い周波数でスイッチングするスイッチング素子と、昇降圧用インダクタンス手段と、整流回路とからなり、前記スイッチング素子のオン期間に前記昇降圧用インダクタンス手段に溜まったエネルギーをすべてオフ期間に出力側へ放出する昇降圧形コンバータ回路と、前記昇降圧形コンバータ回路のスイッチング素子を固定オン時間で動作させ、前記商用交流電圧の少なくとも１サイクルの期間は固定時比率で動作させ、前記昇降圧形コンバータ回路の入力電圧の平均値の２乗に比例させて前記スイッチ素子の動作周期の制御を行い、前記昇降圧形コンバータ回路の出力を一定電力に保つように制御する演算制御回路と、前記昇降圧形コンバータ回路の出力に接続されて一定周波数の交番電圧に変換するインバータ回路と、このインバータ回路の出力に接続され、放電灯に電力供給する一対の出力端子と、からなる放電灯用電子点灯装置を提案するものである。
【０００８】
第３の手段として、商用交流電源に接続される一対の入力端子と、この一対の入力端子に接続され脈流に変換する整流回路と、この整流回路の脈流出力に接続される昇降圧形コンバータ回路であって、この脈流の周波数に比較して十分高い周波数でスイッチングするスイッチング素子と、昇降圧用インダクタンス手段と、整流回路とからなり、前記スイッチング素子のオン期間に前記昇降圧用インダクタンス手段に溜まったエネルギーをすべてオフ期間に出力側へ放出する昇降圧形コンバータ回路と、前記昇降圧コンバータ回路の入力電圧波形に同期した正弦波を発生する電圧発生回路を備え、前記昇降圧形コンバータ回路のスイッチング素子を固定周波数で動作させ、前記電圧発生回路から出力された電圧を電流基準信号とし、前記スイッチング素子の電流が前記電流基準信号に達したとき前記スイッチング素子をオフにする制御を行う演算制御回路と、前記昇降圧形コンバータ回路の出力に接続されて一定周波数の交番電圧に変換するインバータ回路と、このインバータ回路の出力に接続され、放電灯に電力供給する一対の出力端子と、からなる放電灯用電子点灯装置を提案するものである。
【０００９】
第４の手段として、前記昇降圧形コンバータ回路の出力端子間に抵抗器と第１のコンデンサとの直列回路を接続し、前記第１のコンデンサの出力にブリッジインバータ回路を接続し、該ブリッジインバータ回路の出力には第２のコンデンサと負荷を接続し、前記ブリッジインバータ回路には、電流が流れたことを検出する手段を設け、この検出手段の信号により前記抵抗器を短絡することを特徴とする請求項１から３のいずれかに記載の放電灯用電子点灯装置を提案するものである。
【００１０】
第５の手段として、前記昇降圧形コンバータ回路が、入力電圧の平均値の変動に対して、平均値が上昇するに従い前記スイッチング素子の導通幅を狭めるような補正手段を設けることを特徴とする請求項１から４のいずれかに記載の放電灯用電子点灯装置を提案するものである。
【００１１】
第６の手段として、前記昇降圧形コンバータ回路は非絶縁形であることを特徴とする請求項１から５のいずれかに記載の放電灯用電子点灯装置を提案するものである。この非絶縁形の場合には入力側と出力側とが直流的に接続されている点には注意しなければならないが、変圧器を利用した場合と比較して電力伝達効率は高くなる利点がある。
【００１２】
第７の手段として、前記昇降圧形コンバータ回路が絶縁形であることを特徴とする請求項１から６のいずれかに記載の放電灯用電子点灯装置を提案するものである。この絶縁形の場合には非絶縁形と比較して電力伝達効率はやや低くなるが、出力電圧設定の自由度が広くなる利点がある。
【００１５】
【実施例】
図１はこの発明の第１の実施例を示す。なお、安定器には図示した以外に、フィルタや始動回路を有しているが、本発明の構成要件には関係ないので省略している。交流入力端子Ｕ，Ｖに高周波用フィルタ１を接続し、その出力に整流回路２を接続する。整流回路２の出力に昇降圧コンバータ回路３を接続し、その出力にはインバータ回路４を接続する。インバータ回路の出力には負荷である放電灯５が接続される。そして，コンバータ回路のトランスＴの２次電流を変流器ＣＴ１で検出し、ダイオードＤ２、抵抗Ｒ３，Ｒ４、コンデンサＣ３で平均化し乗算器ＭＰ１の一方の入力端子Ｘに接続する。他方の入力端子Ｙには抵抗Ｒ１、Ｒ２で検出した昇降圧コンバータ回路の出力電圧の検出値を接続する。乗算器ＭＰ１の出力は増幅器ＯＡ１の非反転入力端子に接続し、増幅器の反転入力端子には基準値Ｅr1を接続する。増幅器の出力はホト・カプラＯＣのホトダイオードと抵抗Ｒ５を介して出力側制御電圧Ｖcc2 に接続する。ホトトランジスタは制御回路６のパルス幅変調回路（以下ＰＷＭ回路と称す）の入力端子に接続する。ＰＷＭ回路の他方の入力端子は発振回路に接続する。ＰＷＭ回路の出力は駆動回路７を介して昇降圧コンバータ回路３のスイッチング素子Ｑ１の制御端子に接続する。
【００１６】
次にこの実施例の作用を説明する。昇降圧コンバータ回路による高調波抑制方法については、本出願人がすでに出願している（特開平３−２５０７５３）ため本発明に係る部分について説明する。交流電圧を全波整流して得られた脈流電圧をスイッチ素子Ｑ１を利用し、変圧器Ｔの１次巻線に印加して、交流電圧よりはるかに高い周波数（例えば１００ｋＨｚ）で断続印加してエネルギーを蓄え、蓄えられたエネルギーをスイッチ素子のオフ期間にすべて取り出すように動作させる。スイッチ素子のスイッチ周期をＴ、時比率をＤｒ、入力電圧の瞬時値をｅi ，チョークコイルのインダクタンス値をＬとすると、スイッチ素子のオン時の電流ピーク値ｉは(1) 式で表される。
ｉ＝（ｅi ・Ｄｒ・Ｔ）／Ｌ (1)
Ｔ，Ｌは定数であり、Ｄｒを交流入力電圧の１周期の間一定とすると、ピーク値ｉは入力電圧ｅi に比例することになる。
スイッチング１サイクルの期間に流れる交流入力電流の平均値の絶対値ｉavは(2) 式で表される。
ｉａｖ＝（ｅi ・Ｄｒ^２・Ｔ）／２Ｌ (2)
スイッチ素子を固定周波数（Ｔ一定）、固定時比率（Ｄｒ一定）で動作させると、スイッチングの毎サイクルの電流平均値は(2) 式から入力電圧に比例する事が分かる。平均値の連続である入力電流波形は入力電圧波形と相似形となり、高調波成分を含まなくなる。このように動作するコンバータの時比率制御を、出力電力が一定になるようにコンバータトランスの２次電流と出力電圧それぞれの比例値の積（出力電力の比例値）を乗算器ＭＰ１で演算し、その値を基準電圧Ｅr１に保つように増幅器ＯＡ１で誤差増幅し、その誤差信号をホトカプラＯＣで制御回路のＰＷＭ回路に送りスイッチ素子Ｑ１のパルス幅制御する。コンバータの出力に表れる入力周波数成分に対して応答しないように制御速度を遅くすることで、交流入力電圧の１サイクル期間は同じ時比率となる。なお、交流入力電圧の平均値の変動に対しては時比率を制御し負荷側に定電力を供給する。したがって、入力電流を正弦波にするとともに出力に定電力を供給できる。このように動作するコンバータの出力側にブリッジ型のインバータ回路４を接続し、１００Ｈｚ〜３００Ｈｚ程度の低周波数で、スイッチング素子をほぼ１８０°の一定導通角度で動作させることで、負荷である放電灯に定電力の方形波交流電圧を供給できる。
【００１７】
次にインバータ回路４の動作を簡単に説明する。Ｑ２・Ｑ５とＱ３・Ｑ４とを交互にオン・オフさせることで、ブリッジ回路の出力に、コンバータの出力電流の極性を交互に切り替えて供給する。放電灯は一般に、点灯中電圧のバラツキが大きく、かつ経年変化も大きく、点灯時のインピーダンスが小さいため、定電圧や定電流の供給では安定に点灯することができない。本実施例のように、負荷側に供給する電力を定電力とすることで、放電灯を安定に点灯させることができる。なお、電流検出をインバータ回路４の出力電流で行っても制御は可能であるが、低周波電流のため、電流検出用の変流器が大型化し得策でない。
【００１８】
【第２の実施例】
図３は本発明にかかる放電灯用電子点灯装置の第２の実施例である。主たる回路は図１に示す実施例と同様である。整流回路の出力に抵抗Ｒ２１，Ｒ２２、コンデンサＣ２１を接続し平均値を検出し、検出値を反比例回路８の入力に接続する。反比例回路の出力を制御回路６のＰＷＭ回路の入力端子に接続する。ＰＷＭ回路の他方の入力端子は発振回路に接続される。ＰＷＭ回路の出力は駆動回路の入力に接続される。駆動回路の出力は昇降圧コンバータ回路３のスイッチ素子Ｑ１の被制御端子に接続する。
【００１９】
次に動作説明をする。スイッチ素子Ｑ１を交流入力電圧よりはるかに高い周波数（例えば１００ｋＨｚ）でスイッチングさせ、スイッチ素子のオン時に、交流電圧を全波整流して得られた脈流電圧を、変圧器Ｔの１次巻線に印加してエネルギーを蓄え、スイッチ素子のオフ期間に蓄えられたエネルギーをすべて出力側に取り出すように動作させる。このようなコンバータは第１の実施例にて説明したように、スイッチング素子を固定周波数、固定時比率で動作させることで入力電流波形を入力電圧波形と相似形にすることができ、高調波成分を含まなくなる。一方、スイッチの毎サイクル、電流が２次側に放出される昇降圧形コンバータの、スイッチ１サイクルで、出力に伝達されるエネルギー量Ｅｊは（３）式で表される。
Ｅｊ＝（Ｌ・ｉ^２）／２（３）
（３）式から入力電圧の平均値の変動に関わらず、交流入力電圧の各位相でのｉに変化がなければ、出力に伝達されるエネルギー量は変わらないことになる。
（１）式からｉはｅｉ・Ｄｒに比例するのでＤｒをｅｉに反比例させれば出力電力は入力電圧の平均値の変動に対して一定となる。したがって、図３の実施例のように反比例回路８で入力電圧の平均値に反比例する電圧を発生させ、ＰＷＭ回路で反比例信号に応じてパルス幅に変換し、このパルス幅信号でスイッチ素子を駆動すると、入力電圧の平均値が変動しても出力に定電力を供給できる。入力電圧の平均値の比例値は抵抗Ｒ２１≫Ｒ２２であればコンデンサＣ２１の両端で求められる。ＰＷＭ回路で、反比例信号に応じてパルス幅に変換するには、三角波を利用することで簡単にできる。また、時比率Ｄｒを入力電圧の平均値に反比例させることで、交流入力電圧の周波数による変化（周期的変化）に対しては時比率が一定となるため、入力電流は正弦波となる。
【００２０】
【第３の実施例】
図４は本発明にかかる放電灯用電子点灯装置の第３の実施例である。主たる回路は図１に示す実施例と同様である。整流回路の出力に抵抗Ｒ２１，Ｒ２２、コンデンサＣ２１を接続し平均値を検出し、この検出値を２乗回路９の入力に接続し２乗回路の出力を電圧制御発振器ＶＣＯの入力に接続し、ＶＣＯの出力を単安定回路１１の入力に接続する。単安定回路の出力を駆動回路７の入力に接続し、出力を昇降圧形コンバータ回路のスイッチ素子Ｑ１の被駆動端子に接続する。
【００２１】
次に動作説明をする。スイッチ素子Ｑ１を交流電圧よりはるかに高い周波数でスイッチングさせ、スイッチ素子のオン時に、交流電圧を全波整流して得られた脈流電圧を、変圧器Ｔの１次巻線に印加してエネルギーを蓄え、スイッチ素子のオフ期間に蓄えられたエネルギーをすべて取り出すように動作させる。スイッチ素子のスイッチ周期をＴ、時比率をＤｒ、入力電圧の瞬時値をｅｉ，１次巻線のインダクタンス値をＬとした時の、スイッチ素子のオン時に入力に流れる電流平均値ｉａｖは（２）式で表される。（２）式においてスイッチのオン時間をｔｏｎとすると、（４）式のように改められる。
ｉａｖ＝（ｅｉ・ｔｏｎ^２）／２ＬＴ（４）
（４）式にｅｉを掛けると入力電力の瞬時値ｐになり（５）式で表される。
ｐ＝（ｅｉ ^２・ｔｏｎ^２）／２ＬＴ（５）
（５）式から、ｔｏｎを一定にし、周期Ｔを入力電圧の平均値の２乗に比例させると入力電力は一定になり入力電圧の平均値の変動の影響を受けないことが理解できる。
【００２２】
この実施例では、入力電圧の平均値の比例値を２乗回路９で二乗し、この平均値の二乗値に電圧制御発振器ＶＣＯの発振周期を比例させる。周期は周波数の逆数のためＶＣＯの発振周期は入力電圧の平均値の２乗に反比例することになる。ＶＣＯの発振信号を単安定回路で固定パルス幅のパルスを発生させることで、周波数に影響されない固定パルス幅を得ることができる。単安定回路の出力を駆動回路で駆動信号とし、コンバータ回路のスイッチ素子を駆動する。二乗回路は入力電圧の平均値で動作しているため、スイッチ素子の動作周期、パルス幅は交流入力電圧の周波数による電圧の変化（周期的な変化）の影響を受けず、固定周波数、固定時比率となる。したがって入力電流波形は入力電圧波形と相似形となり、高調波成分を含まなくなり、入力電力は一定となる。入力電力は内部損失を差し引いてインバータ出力に接続された負荷の放電灯に伝達される。放電灯は電圧、電流にバラツキがあるが、極端な差はないため、放電灯のバラツキによる内部損失の変化はほとんどないといえる。したがって、負荷にはほぼ定電力が伝達される。なお、入力電圧の二乗に比例する信号を得るには掛け算器の入力端子ＸとＹに入力電圧の比例値を入れてやればよい。
【００２３】
【第４の実施例】
図５は本発明にかかる放電灯用電子点灯装置の第４の実施例である。整流回路の出力に抵抗Ｒ２１，Ｒ２２、コンデンサＣ２１を接続し平均値電圧を検出し、さらに抵抗Ｒ４１とＲ４２で整流電圧の比例値を検出する。コンデンサＣ２１の検出値を反比例回路８に接続し、反比例回路の出力とＲ４２の電圧とを掛け算器ＭＰ４で掛け算する。掛け算器の出力と変流器ＣＴ４で検出した変圧器１次巻線電流の検出値をコンパレータＣＬ４のそれぞれ非反転入力、反転入力に接続する。コンパレータの出力と発振器ＯＳＣの出力をパルス幅回路に接続する。パルス幅回路の出力を駆動回路７に接続し、駆動回路の出力を昇降圧形コンバータ回路３のスイッチング素子Ｑ１の被駆動端子に接続する。
【００２４】
次に動作説明をする。スイッチング素子Ｑ１を交流電圧よりはるかに高い周波数でスイッチングさせ、スイッチング素子Ｑ１のオン時に、交流電圧を全波整流して得られた脈流電圧を、変圧器Ｔの１次巻線に印加してエネルギーを蓄え、スイッチング素子のオフ期間に蓄えられたエネルギーをすべて出力側に放出するように動作する昇降圧形コンバータにおいてスイッチング素子のスイッチ周期をＴ、時比率をＤｒ、入力電圧の瞬時値をｅｉ，１次巻線のインダクタンス値をＬとすると、スイッチング素子のオン時に入力に流れる電流ピーク値ｉは（１）式で表される。一方、スイッチング素子のオン期間に蓄えられるエネルギー量Ｅｊは（３）式で表される。（３）式からスイッチング素子のオン期間を入力電圧の１サイクルの期間一定にし、入力電圧の平均値に関係なく入力電圧の各位相でスイッチング素子のオン期間の電流ピーク値を一定にすると、入力電力は入力電圧の平均値の変動に関係なく一定になる。
【００２５】
この実施例においては、入力電圧の平均値の比例値に反比例する電圧を反比例回路８で作り、この反比例電圧と入力電圧（整流電圧）の比例値とを掛け算器ＭＰ４で掛け算する。ｋ１・ｅｉ ×（１／（ｋ２・ｅｉａｖ））となるので出力には入力電圧に相似で入力電圧の平均値の変動に影響されない電圧が現れる。掛け算器の出力電圧と、ＣＴ４で検出したトランスＴの１次巻線電流の比例値とをコンパレータＣＬ４で比較する。ＰＷＭ回路では発振器からのハイレベル信号でハイレベル出力、コンパレータからのローレベル信号でローレベル出力を駆動回路７へ送る。駆動回路はＰＷＭ回路からの信号に従いスイッチ素子Ｑ１を駆動する。なお、これらのハイレベル、ローレベルの符号はどのようにしても良く、変流器ＣＴ４からの電圧が掛け算器からの電圧と一致した時点で、スイッチング素子をオフさせれば良い。このようにスイッチング素子Ｑ１を動かすことで、入力電流を正弦波とし、入力電力を一定にする。以下、第３の実施例と同様にして負荷の放電灯５にはほぼ一定電力が伝達される。
【００２６】
【第５の実施例】
図６は本発明にかかる放電灯用電子点灯装置の第５の実施例である。入力端子にトランスＴ４の１次巻線を接続し、２次巻線を同期発振回路１２に接続する。同期発振回路の出力は正弦波発生回路１３の入力と接続する。同期発振回路１２の他の入力端子は正弦波発生回路１３の出力に接続され、交流入力電圧と正弦波発生回路１３の出力とが同期した信号となるように同期発振回路１２が動作する。正弦波発生回路１３の出力とトランスの１次電流を検出する変流器ＣＴ４の出力をコンパレータＣＬ４のそれぞれ非反転入力端子と反転入力端子に接続し、出力をパルス幅発生回路の入力に接続する。ＰＷＭ回路の他方の入力にはさらに同期発振回路１２の出力に接続する。ＰＷＭ回路の出力を駆動回路７に接続し、駆動回路７の出力をスイッチング素子Ｑ１の制御端子に接続する。
【００２７】
動作説明をすると、交流入力電圧に比例した電圧を変圧器Ｔ４で検出し、フェーズ・ロックト・ループＰＬＬなどを用いた同期発振回路１２と正弦波発生回路１３で、交流入力電圧に比例した電圧に同期し、相似な波形を発生させ、この電圧とＣＴ４で検出したトランスＴの１次巻線電流の比例値とをコンパレータＣＬ４で比較する。コンパレータ出力と同期発振回路１２からの信号でＰＷＭ回路はスイッチ素子Ｑ１の駆動信号を発生する。この信号にしたがって駆動回路はＱ１を駆動する。第１の実施例と同じようにコンパレータやＰＷＭ回路のハイレベル、ローレベルの符号は任意に選定して、変圧器ＣＴ４からの電圧が正弦波発生回路からの電圧と一致した時点で、スイッチング素子Ｑ１をオフさせれば良い。このようにスイッチング素子Ｑ１を動かすことで、入力電流を正弦波とし、入力電力を一定にする。以下、第３の実施例と同様にして負荷の放電灯５にはほぼ一定電力が伝達される。
【００２８】
【第６の実施例】
図７は第６の実施例である。放電灯の点灯直前は、２７０Ｖ程度の比較的高い電圧が必要であるが、点灯直後の電圧は１０Ｖ前後と非常に低くなる。このため、コンバータ出力に接続されている容量の大きなコンデンサＣ１に溜まっていたエネルギーは、放電灯５の点灯と同時に急激に放出される。このため過大な電流がインバータ回路４の中のスイッチング素子に流れるため、出力電流を流すための電流容量以上の素子を使用するなどの対策が必要になる。そこで、図に示すようにコンバータ出力に接続された大きな容量のコンデンサＣ１の後に抵抗と小さな容量のコンデンサＣ４を接続しこの小容量のコンデンサＣ４の両端にインバータ回路４を接続することで、放電灯５の点灯直後の過大な電流が流れるのを抵抗Ｒ７で制限し、放電灯５の点灯後はリレーＲＬの接点ｒｌで抵抗Ｒ７を短絡するようにしたものである。なお、リレーＲＬの代わりにサイリスタやトライアック、トランジスタなどを使用しても良い。
【００２９】
【第７の実施例】
図８は第７の実施例を示す。以上の説明では昇降圧コンバータ回路３を絶縁形で説明してきたが、チョークコイルＬを用いた非絶縁の反転チョッパ回路でも同じ効果が得られる。図８に反転チョッパ形による回路を示す。この非絶縁形の場合には入力側と出力側とが直流的に接続されている点については注意しなければならないが、変圧器を利用した絶縁形の実施例と比較して電力伝達効率は高くなる利点がある。
【００３０】
【入力電圧変動への対策】
以上説明してきた実施例では入力電力を一定に制御するため、入力電圧が大幅に変わる場合、例えば８５Ｖから２６４Ｖｒｍｓまで変わるワールドワイド仕様のような場合、入力電圧につれて入力電流も大きく変わる。このため入力側の損失が変わり、出力に伝達される電力も変わることになる。これを避けるため、入力電力の平均値にしたがって、制御に補正を行うことで出力に伝達される電力を一定にすることができる。入力電圧が上昇するにつれて入力電流が減少するので、損失も低減していく。図３に示す実施例の場合、入力電圧の平均値が上昇すると、上昇の割合以上にパルス幅が狭くなるようにすればよい。簡単な方法として抵抗Ｒ２１とＲ２２の抵抗値の比率を変えることで実現できる。抵抗値がＲ２１≫Ｒ２２の場合には、コンデンサＣ２１には平均値が現れ、抵抗Ｒ２１とＲ２２の抵抗値を近付けると、ピーク充電に近づくため入力電圧が上昇するほど検出値が増加する。しかし、入力電圧の最低と最大での損失差の出力電力に対する割合は２〜４％程度のため大きな補正は必要無く、抵抗Ｒ２１とＲ２２を回路の設計条件で若干調整すれば良い。なお、抵抗Ｒ２１とＲ２２の抵抗値を調整するとコンデンサＣ２１の電圧が上がるので、Ｒ２２に影響を与えない程度の抵抗で分圧し、反比例回路に送る。図４、図５の実施例も同じである。図６の実施例では、新たに入力電圧の平均値検出回路を設け、ＣＴ４による電流検出回路に入力電圧の平均値を適当に加えてやると、入力の平均電圧が上昇すると検出電流が見掛上大きくなり、パルス幅を狭めるようになる。この結果、入力電圧の平均値が上昇し、１次側の損失が減少しても、出力に伝達される電力量は一定に保たれる。なお、入力電圧があまり変動しない場合は補正の必要はない。
【００３１】
【発明の効果】
以上説明してきたように、この発明によれば、高輝度放電灯の電子安定器の構成を、昇降圧チョッパー回路を電流リッセトモード・固定時比率で動作させることで、入力電流を正弦波とするとともにすると共に、出力に定電力を供給し、後段のブリッジインバータを低周波で動作させることで、負荷である放電灯に安定した定電力を供給するようにしたため、従来の電子安定器と比べ同程度の部品点数で、入力電流を正弦波状とし高調波を大幅に低減できる。
【図面の簡単な説明】
【図１】本発明にかかる放電灯用電子点灯装置の第１の実施例を示す。
【図２】図１に示す実施例の動作を説明するための電流波形図である。
【図３】本発明にかかる放電灯用電子点灯装置の第２の実施例を示す。
【図４】本発明にかかる放電灯用電子点灯装置の第３の実施例を示す。
【図５】本発明にかかる放電灯用電子点灯装置の第４の実施例を示す。
【図６】本発明にかかる放電灯用電子点灯装置の第５の実施例を示す。
【図７】本発明にかかる放電灯用電子点灯装置の第６の実施例を示す。
【図８】本発明にかかる放電灯用電子点灯装置の第７の実施例を示す。
【図９】放電灯の電流等の波形図である。
【図１０】従来の放電灯用電子点灯装置の一例である。
【符号の説明】
１…高周波用フィルタ２…整流回路３…昇降圧形コンバータ回路
４…インバータ回路５…放電灯６…演算制御回路７…駆動回路
８…反比例回路９…二乗回路１０…電圧制御発振器１１…単安定回路
１２…同期発振回路１３…正弦波発生回路１５…放電灯点灯確認回路
１６…ブリッジ・倍電圧切り替え整流回路
ＣＬ４…コンパレータＣＴ，ＣＴ４…変流器Ｅｒ１…基準電圧
Ｌ…昇降圧用インダクタンスＯＡ１…増幅器ＭＰ…乗算器ＲＬ…リレー[0001]
[Industrial application fields]
The present invention relates to an electronic lighting device for a discharge lamp that makes a current taken out from an AC power source into a sine wave shape and performs stable power control by controlling the power of the discharge lamp.
[0002]
[Prior art]
Most conventional lighting devices for discharge lamps are based on magnetic leakage transformers, and power control is not performed. When the input voltage fluctuates, the power consumption of the discharge lamp fluctuates, the brightness changes, and the life of the discharge lamp is affected. As shown in FIG. 9, the power consumption of the discharge lamp also changes depending on the voltage change of the commercial voltage as shown in FIG. There was a problem. In addition to the problems described above, the magnetic leakage transformer system is large and heavy, and is not convenient to carry. In recent years, electronic lighting devices using a high-frequency modulation system using high-speed switching elements have begun to be used.
[0003]
An example of a conventional electronic lighting device for a discharge lamp is shown in FIG. In this circuit, the AC voltage is rectified by the rectifier circuit 21. When the input voltage is 100V system, SW1 is closed to double voltage rectification. When the input voltage is 200V system, SW1 is opened and full-wave rectification is performed. A voltage is obtained and converted into a voltage required for the discharge lamp by the step-down chopper circuit 22. The converted DC voltage is switched between conduction of the switching elements Q2, Q5 and Q3, Q4 of the bridge circuit 23 to generate a rectangular wave AC voltage and supplied to the discharge lamp. By operating the step-down chopper circuit 22 at a high frequency, a small and light ballast can be realized.
[0004]
[Problems to be solved by the invention]
However, in such a conventional electronic lighting device for a discharge lamp, the input current has a waveform that flows only at a part of the electrical angle of the AC cycle, and a large number of harmonic currents flow through the distribution system. Caused harmonic disturbance. In addition, it will not be able to satisfy the harmonic regulations that will be implemented soon, which will be a big problem in practice. In order to satisfy the harmonic regulation, harmonic suppression means such as a boost chopper must be used in the previous stage. However, if this is done, both the boost chopper and the buck chopper are required, and there is a problem that the cost increases and the size increases.
[0005]
This invention pays attention to such a problem, and in an electronic lighting device for a discharge lamp, an input current is made sinusoidal to reduce harmonics, and at the same time, a stable luminance without flickering is generated in a discharge lamp as a load. Is an issue.
[0006]
[Means for Solving the Problems]
In order to solve this problem, the present invention controls the step-up / down chopper circuit to supply constant power to the output while suppressing harmonics, and to supply low-frequency AC constant power without flickering to the discharge lamp as a load. To do. First, the following means are proposed as the first basic means.A pair of input terminals connected to a commercial AC power source, a rectifier circuit connected to the pair of input terminals and converting to a pulsating current, and a step-up / step-down converter circuit connected to the pulsating current output of the rectifying circuit, It consists of a switching element that switches at a frequency sufficiently higher than the frequency of the pulsating flow, a step-up / step-down inductance means, and a rectifier circuit. All energy accumulated in the step-up / step-down inductance means during the ON period of the switching element is turned off. The step-up / step-down converter circuit that discharges to the output side during the period, and the switching element of the step-up / step-down converter circuit are operated at a fixed frequency, and at least one cycle period of the commercial AC voltage is operated at a fixed time ratio, Time ratio of the switching element so as to be inversely proportional to the average value of the input voltage of the buck-boost converter circuit An operation control circuit for controlling the output of the buck-boost converter circuit to maintain a constant power, an inverter circuit connected to the output of the buck-boost converter circuit and converting it into an alternating voltage of a constant frequency, The present invention proposes an electronic lighting device for a discharge lamp comprising a pair of output terminals connected to the output of the inverter circuit and supplying power to the discharge lamp.
[0007]
As a second meansA pair of input terminals connected to a commercial AC power source, a rectifier circuit connected to the pair of input terminals and converting to a pulsating current, and a step-up / step-down converter circuit connected to the pulsating current output of the rectifying circuit, The switching element switching at a sufficiently high frequency compared to the frequency of the pulsating flow, the step-up / step-down inductance means, and the rectifier circuit, all the energy accumulated in the step-up / step-down inductance means during the ON period of the switching element. A step-up / down converter circuit that discharges to the output side during an off period, and a switching element of the step-up / down converter circuit is operated at a fixed on-time, and at least one cycle of the commercial AC voltage is operated at a fixed time ratio; Control of the operation cycle of the switch element in proportion to the square of the average value of the input voltage of the buck-boost converter circuit And an arithmetic control circuit for controlling the output of the step-up / step-down converter circuit to maintain a constant power, an inverter circuit connected to the output of the step-up / step-down converter circuit and converting it to an alternating voltage of a constant frequency, and the inverter An electronic lighting device for a discharge lamp, comprising a pair of output terminals connected to the output of the circuit and supplying power to the discharge lampThis is a proposal.
[0008]
As a third meansA pair of input terminals connected to a commercial AC power source, a rectifier circuit connected to the pair of input terminals and converting to a pulsating current, and a step-up / step-down converter circuit connected to the pulsating current output of the rectifying circuit, The switching element switching at a sufficiently high frequency compared to the frequency of the pulsating flow, the step-up / step-down inductance means, and the rectifier circuit, all the energy accumulated in the step-up / step-down inductance means during the ON period of the switching element. A buck-boost converter circuit that discharges to the output side during an off period, and a voltage generation circuit that generates a sine wave synchronized with the input voltage waveform of the buck-boost converter circuit, the switching element of the buck-boost converter circuit having a fixed frequency The voltage output from the voltage generation circuit is used as a current reference signal, and the current of the switching element is An arithmetic control circuit that performs control to turn off the switching element when the current reference signal is reached, an inverter circuit that is connected to the output of the buck-boost converter circuit and converts the voltage into an alternating voltage, and the inverter circuit An electronic lighting device for a discharge lamp, comprising a pair of output terminals connected to the output of the power supply and supplying power to the discharge lampThis is a proposal.
[0009]
As a fourth meansA series circuit of a resistor and a first capacitor is connected between the output terminals of the buck-boost converter circuit, a bridge inverter circuit is connected to the output of the first capacitor, and the output of the bridge inverter circuit is The second capacitor and a load are connected, and the bridge inverter circuit is provided with means for detecting that a current has flowed, and the resistor is short-circuited by a signal from the detection means. The electronic lighting device for a discharge lamp according to any one of 3This is a proposal.
[0010]
As a fifth means5. The step-up / step-down converter circuit is provided with correction means for narrowing the conduction width of the switching element as the average value rises with respect to fluctuations in the average value of the input voltage. An electronic lighting device for a discharge lamp according to any one ofThis is a proposal.
[0011]
As a sixth means6. The electronic lighting device for a discharge lamp according to claim 1, wherein the step-up / step-down converter circuit is a non-insulating type. In the case of this non-insulated type, it must be noted that the input side and the output side are connected in a DC manner, but there is an advantage that the power transfer efficiency is higher than when a transformer is used. is there.
[0012]
As a seventh means7. The electronic lighting device for a discharge lamp according to claim 1, wherein the step-up / step-down converter circuit is an insulating type. In the case of this insulation type, the power transmission efficiency is slightly lower than that of the non-insulation type, but there is an advantage that the degree of freedom in setting the output voltage is widened.
[0015]
【Example】
FIG. 1 shows a first embodiment of the present invention. Although the ballast has a filter and a starting circuit other than those shown in the figure, they are omitted because they are not related to the configuration requirements of the present invention. The high frequency filter 1 is connected to the AC input terminals U and V, and the rectifier circuit 2 is connected to the output. A buck-boost converter circuit 3 is connected to the output of the rectifier circuit 2, and an inverter circuit 4 is connected to the output. A discharge lamp 5 as a load is connected to the output of the inverter circuit. Then, the secondary current of the transformer T of the converter circuit is detected by the current transformer CT1, averaged by the diode D2, resistors R3 and R4, and the capacitor C3 and connected to one input terminal X of the multiplier MP1. The other input terminal Y is connected to the detected value of the output voltage of the buck-boost converter circuit detected by the resistors R1 and R2. The output of the multiplier MP1 is connected to the non-inverting input terminal of the amplifier OA1, and the reference value Er1 is connected to the inverting input terminal of the amplifier. The output of the amplifier isG-Connect to the output side control voltage Vcc2 via the photodiode of the coupler OC and the resistor R5. The phototransistor is connected to an input terminal of a pulse width modulation circuit (hereinafter referred to as a PWM circuit) of the control circuit 6. The other input terminal of the PWM circuit is connected to the oscillation circuit. The output of the PWM circuit is connected to the control terminal of the switching element Q1 of the buck-boost converter circuit 3 via the drive circuit 7.
[0016]
Next, the operation of this embodiment will be described. The harmonic suppression method using the buck-boost converter circuit has already been filed by the present applicant (Japanese Patent Laid-Open No. 3-250753), and therefore, the portion according to the present invention will be described. The pulsating voltage obtained by full-wave rectification of the AC voltage is applied to the primary winding of the transformer T using the switching element Q1, and intermittently applied at a frequency (for example, 100 kHz) much higher than the AC voltage. Energy is stored, and the stored energy is operated so as to be taken out during the OFF period of the switch element. When the switch period of the switch element is T, the duty ratio is Dr, the instantaneous value of the input voltage is ei, and the inductance value of the choke coil is L, the current when the switch element is onPeak value iIs expressed by equation (1).
i = (ei · Dr · T) / L (1)
T and L are constants. When Dr is constant during one period of the AC input voltage, the peak value i is proportional to the input voltage ei.
The absolute value iav of the average value of the AC input current flowing during the period of one switching cycle is expressed by equation (2).
iav = (ei · Dr²・ T) / 2L (2)
When the switch element is operated at a fixed frequency (T constant) and a fixed duty ratio (Dr constant), the average current value of each cycle of switching is calculated from the equation (2) to the input voltage.ProportionalI understand that. The input current waveform that is a series of average values is similar to the input voltage waveform and does not contain harmonic components. For the duty ratio control of the converter operating in this way, the product of the proportional values of the secondary current of the converter transformer and the output voltage (proportional value of the output power) is calculated by the multiplier MP1 so that the output power becomes constant, The error is amplified by the amplifier OA1 so as to keep the value at the reference voltage Er1, and the error signal is sent to the PWM circuit of the control circuit by the photocoupler OC to control the pulse width of the switch element Q1. By reducing the control speed so as not to respond to the input frequency component appearing in the output of the converter, one cycle period of the AC input voltage has the same time ratio. Note that the constant ratio is supplied to the load side by controlling the duty ratio with respect to the fluctuation of the average value of the AC input voltage. Therefore, the input current can be a sine wave and constant power can be supplied to the output. The bridge type inverter circuit 4 is connected to the output side of the converter that operates in this way, and the switching element is operated at a constant conduction angle of approximately 180 ° at a low frequency of about 100 Hz to 300 Hz, so that a discharge lamp as a load Can be supplied with a square wave AC voltage of constant power.
[0017]
Next, the operation of the inverter circuit 4 will be briefly described. By alternately turning on / off Q2 and Q5 and Q3 and Q4, the polarity of the output current of the converter is alternately switched and supplied to the output of the bridge circuit. In general, a discharge lamp has a large variation in voltage during lighting, a large secular change, and a low impedance at the time of lighting. Therefore, it cannot be stably lit by supplying a constant voltage or a constant current. As in the present embodiment, by setting the power supplied to the load side to be constant power, the discharge lamp can be lit stably. Although control is possible even if current detection is performed with the output current of the inverter circuit 4, the current detection current transformer becomes large in size because of the low frequency current, which is not a good idea.
[0018]
[Second embodiment]
FIG. 3 shows a second embodiment of the electronic lighting device for a discharge lamp according to the present invention. The main circuit is the same as that of the embodiment shown in FIG. The resistors R21 and R22 and the capacitor C21 are connected to the output of the rectifier circuit to detect the average value, and the detected value is connected to the input of the inverse proportional circuit 8. The output of the inverse proportional circuit is connected to the input terminal of the PWM circuit of the control circuit 6. The other input terminal of the PWM circuit is connected to the oscillation circuit. The output of the PWM circuit is connected to the input of the drive circuit. The output of the drive circuit is connected to the controlled terminal of the switch element Q1 of the buck-boost converter circuit 3.
[0019]
Next, the operation will be described. The switching element Q1 is switched at a frequency (for example, 100 kHz) much higher than the AC input voltage, and when the switching element is ON, the pulsating voltage obtained by full-wave rectification of the AC voltage is used as the primary winding of the transformer T. To store the energy, and operate so as to extract all the energy stored during the OFF period of the switch element to the output side. As described in the first embodiment, such a converter can make the input current waveform similar to the input voltage waveform by operating the switching element at a fixed frequency and a fixed duty ratio, and can generate harmonic components. Is not included. On the other hand, the energy amount Ej transmitted to the output in one cycle of the buck-boost converter in which the current is discharged to the secondary side every cycle of the switch is expressed by the following equation (3).
Ej = (L · i²) / 2 (3)
(3) From the equation, regardless of fluctuations in the average value of the input voltage, if there is no change in i at each phase of the AC input voltage, the amount of energy transmitted to the output will not change.
(1) Since i is proportional to ei · Dr from the equation (1), if Dr is inversely proportional to ei, the output power becomes constant with respect to the fluctuation of the average value of the input voltage. Therefore, as in the embodiment of FIG. 3, the inversely proportional circuit 8 generates a voltage inversely proportional to the average value of the input voltage, the PWM circuit converts the pulse width according to the inversely proportional signal, and the switch element is driven by this pulse width signal. Then, constant power can be supplied to the output even if the average value of the input voltage varies. The proportional value of the average value of the input voltage is obtained at both ends of the capacitor C21 if the resistance R21 >> R22. In a PWM circuit, conversion to a pulse width according to an inversely proportional signal can be easily performed by using a triangular wave. Further, by making the duty ratio Dr inversely proportional to the average value of the input voltage, the duty ratio becomes constant with respect to the change (periodic change) due to the frequency of the AC input voltage, so the input current becomes a sine wave.
[0020]
[Third embodiment]
FIG. 4 shows a third embodiment of the electronic lighting device for a discharge lamp according to the present invention. The main circuit is the same as that of the embodiment shown in FIG. The resistors R21 and R22 and the capacitor C21 are connected to the output of the rectifier circuit to detect the average value, the detected value is connected to the input of the square circuit 9, and the output of the square circuit is connected to the input of the voltage controlled oscillator VCO. The output of the VCO is connected to the input of the monostable circuit 11. The output of the monostable circuit is connected to the input of the drive circuit 7, and the output is connected to the driven terminal of the switch element Q1 of the buck-boost converter circuit.
[0021]
Next, the operation will be described. The switching element Q1 is switched at a frequency much higher than the AC voltage, and when the switching element is turned on, the pulsating voltage obtained by full-wave rectification of the AC voltage is applied to the primary winding of the transformer T for energy. And is operated so as to extract all of the energy stored during the OFF period of the switch element. When the switch period of the switch element is T, the duty ratio is Dr, the instantaneous value of the input voltage is ei, and the inductance value of the primary winding is L, the average current value iav flowing to the input when the switch element is on is (2 It is expressed by the formula. In the equation (2), when the on-time of the switch is ton, the equation is revised as in the equation (4).
iav = (ei ・ ton²) / 2LT (4)
Multiplying (4) by ei gives the instantaneous value p of the input power and is expressed by (5).
p = (ei²・ Ton²) / 2LT (5)
From equation (5), it can be understood that when the ton is constant and the period T is proportional to the square of the average value of the input voltage, the input power becomes constant and is not affected by the fluctuation of the average value of the input voltage.
[0022]
In this embodiment, the proportional value of the average value of the input voltage is squared by the square circuit 9, and the oscillation period of the voltage controlled oscillator VCO is proportional to the square value of the average value. Since the period is the reciprocal of the frequency, the oscillation period of the VCO is inversely proportional to the square of the average value of the input voltage. By generating a pulse having a fixed pulse width from the oscillation signal of the VCO with a monostable circuit, a fixed pulse width that is not influenced by the frequency can be obtained. The output of the monostable circuit is used as a drive signal by the drive circuit, and the switch element of the converter circuit is driven. Since the squaring circuit operates at the average value of the input voltage, the operating cycle and pulse width of the switch element are not affected by the voltage change (periodic change) due to the frequency of the AC input voltage, and are fixed at a fixed frequency. It becomes a ratio. Therefore, the input current waveform is similar to the input voltage waveform, does not include harmonic components, and the input power is constant. The input power is transmitted to the discharge lamp of the load connected to the inverter output after subtracting the internal loss. Although there are variations in voltage and current in discharge lamps, there is no extreme difference, so it can be said that there is almost no change in internal loss due to variations in discharge lamps. Therefore, almost constant power is transmitted to the load. In order to obtain a signal proportional to the square of the input voltage, a proportional value of the input voltage may be input to the input terminals X and Y of the multiplier.
[0023]
[Fourth embodiment]
FIG. 5 shows a fourth embodiment of the electronic lighting device for a discharge lamp according to the present invention. The resistors R21 and R22 and the capacitor C21 are connected to the output of the rectifier circuit to detect the average value voltage, and the resistors R41 and R42 detect the proportional value of the rectified voltage. The detection value of the capacitor C21 is connected to the inverse proportional circuit 8, and the output of the inverse proportional circuit and the voltage of R42 are multiplied by the multiplier MP4. The output of the multiplier and the detected value of the primary winding current detected by the current transformer CT4 are connected to the non-inverting input and the inverting input of the comparator CL4, respectively. The output of the comparator and the output of the oscillator OSC are connected to the pulse width circuit. The output of the pulse width circuit is connected to the drive circuit 7, and the output of the drive circuit is connected to the driven terminal of the switching element Q1 of the buck-boost converter circuit 3.
[0024]
Next, the operation will be described. The switching element Q1 is switched at a frequency much higher than the AC voltage, and when the switching element Q1 is turned on, the pulsating voltage obtained by full-wave rectification of the AC voltage is applied to the primary winding of the transformer T. In a buck-boost converter that operates to store energy and release all energy stored during the off period of the switching element to the output side, the switching period of the switching element is T, the time ratio is Dr, and the instantaneous value of the input voltage is ei , If the inductance value of the primary winding is L, the peak current value i flowing to the input when the switching element is turned on is expressed by equation (1). On the other hand, the amount of energy Ej stored during the ON period of the switching element is expressed by equation (3). (3) When the ON period of the switching element is made constant for one cycle of the input voltage and the current peak value of the ON period of the switching element is constant for each phase of the input voltage regardless of the average value of the input voltage, The power becomes constant regardless of the fluctuation of the average value of the input voltage.
[0025]
In this embodiment, a voltage that is inversely proportional to the proportional value of the average value of the input voltage is generated by the inverse proportional circuit 8, and this inverse proportional voltage and the proportional value of the input voltage (rectified voltage) are multiplied by the multiplier MP4. Since k1 · ei × (1 / (k2 · ei av)), a voltage that is similar to the input voltage and is not affected by the fluctuation of the average value of the input voltage appears in the output. The comparator CL4 compares the output voltage of the multiplier with the proportional value of the primary winding current of the transformer T detected by CT4. The PWM circuit sends a high level output to the drive circuit 7 by a high level signal from the oscillator and a low level output by a low level signal from the comparator. The drive circuit drives the switch element Q1 in accordance with a signal from the PWM circuit. These high level and low level codes may be used in any way, and the switching element may be turned off when the voltage from the current transformer CT4 coincides with the voltage from the multiplier. By moving the switching element Q1 in this way, the input current is made a sine wave and the input power is made constant. Thereafter, substantially constant power is transmitted to the load discharge lamp 5 in the same manner as in the third embodiment.
[0026]
[Fifth embodiment]
FIG. 6 shows a fifth embodiment of the electronic lighting device for a discharge lamp according to the present invention. The primary winding of the transformer T4 is connected to the input terminal, and the secondary winding is connected to the synchronous oscillation circuit 12. The output of the synchronous oscillation circuit is connected to the input of the sine wave generation circuit 13. The other input terminal of the synchronous oscillation circuit 12 is connected to the output of the sine wave generation circuit 13, and the synchronous oscillation circuit 12 operates so that the AC input voltage and the output of the sine wave generation circuit 13 are synchronized. The output of the sine wave generation circuit 13 and the output of the current transformer CT4 that detects the primary current of the transformer are connected to the non-inverting input terminal and the inverting input terminal of the comparator CL4, respectively, and the output is connected to the input of the pulse width generation circuit. . The other input of the PWM circuit is further connected to the output of the synchronous oscillation circuit 12. The output of the PWM circuit is connected to the drive circuit 7, and the output of the drive circuit 7 is connected to the control terminal of the switching element Q1.
[0027]
To explain the operation, a voltage proportional to the AC input voltage is detected by the transformer T4, and the voltage is proportional to the AC input voltage by the synchronous oscillation circuit 12 and the sine wave generation circuit 13 using a phase locked loop PLL or the like. A similar waveform is generated in synchronization, and this voltage is compared with the proportional value of the primary winding current of the transformer T detected by CT4 by the comparator CL4. The PWM circuit generates a drive signal for the switch element Q1 based on the comparator output and the signal from the synchronous oscillation circuit 12. In accordance with this signal, the driving circuit drives Q1. Same as the first exampleConThe signs of the high level and low level of the palator and PWM circuit are arbitrarily selected, and the switching element Q1 may be turned off when the voltage from the transformer CT4 matches the voltage from the sine wave generation circuit. By moving the switching element Q1 in this way, the input current is made a sine wave and the input power is made constant. Thereafter, substantially constant power is transmitted to the load discharge lamp 5 in the same manner as in the third embodiment.
[0028]
[Sixth embodiment]
FIG. 7 shows a sixth embodiment. A relatively high voltage of about 270 V is required immediately before the discharge lamp is lit, but the voltage immediately after lighting is as low as around 10 V. For this reason, the energy accumulated in the large-capacitance capacitor C1 connected to the converter output is suddenly released simultaneously with the lighting of the discharge lamp 5. For this reason, since an excessive current flows through the switching element in the inverter circuit 4, it is necessary to take measures such as using an element having a current capacity larger than that for flowing the output current. Therefore, as shown in the figure, a large capacity capacitor C1 connected to the converter output is followed by a resistor and a small capacity capacitor C4, and an inverter circuit 4 is connected to both ends of the small capacity capacitor C4, thereby providing a discharge lamp. An excessive current immediately after the lighting of 5 is limited by the resistor R7, and after the discharge lamp 5 is lit, the resistor R7 is short-circuited by the contact rl of the relay RL. Note that a thyristor, triac, transistor, or the like may be used instead of the relay RL.
[0029]
[Seventh embodiment]
FIG. 8 shows a seventh embodiment. In the above description, the step-up / step-down converter circuit 3 has been described as an insulation type, but the same effect can be obtained with a non-insulated inverting chopper circuit using a choke coil L. FIG. 8 shows an inverted chopper type circuit. In the case of this non-insulated type, it must be noted that the input side and the output side are connected in a DC manner, but the power transfer efficiency is lower than that of the insulated type example using a transformer. There is an advantage of becoming higher.
[0030]
[Countermeasures against fluctuations in input voltage]
In the embodiment described above, since the input power is controlled to be constant, when the input voltage changes greatly, for example, in the case of the world wide specification which changes from 85 V to 264 Vrms, the input current changes greatly according to the input voltage. For this reason, the loss on the input side changes, and the power transmitted to the output also changes. In order to avoid this, the power transmitted to the output can be made constant by correcting the control according to the average value of the input power. Since the input current decreases as the input voltage increases, the loss also decreases. In the case of the embodiment shown in FIG. 3, when the average value of the input voltage increases, the pulse width may be made narrower than the rate of increase. As a simple method, it can be realized by changing the ratio of the resistance values of the resistors R21 and R22. When the resistance value is R21 >> R22, an average value appears in the capacitor C21, and when the resistance values of the resistors R21 and R22 are brought close to each other, the detected value increases as the input voltage increases because it approaches peak charging. However, since the ratio of the difference between the minimum and maximum loss of the input voltage to the output power is about 2 to 4%, no large correction is necessary, and the resistors R21 and R22 may be slightly adjusted according to the circuit design conditions. When the resistance values of the resistors R21 and R22 are adjusted, the voltage of the capacitor C21 increases. Therefore, the voltage is divided by a resistance that does not affect the R22 and sent to the inverse proportional circuit. The same applies to the embodiments of FIGS. In the embodiment shown in FIG. 6, a new input voltage average value detection circuit is provided, and if the average value of the input voltage is appropriately added to the current detection circuit based on CT4, the detected current appears when the input average voltage increases. It becomes larger and the pulse width becomes narrower. As a result, even if the average value of the input voltage increases and the loss on the primary side decreases, the amount of power transmitted to the output is kept constant. If the input voltage does not fluctuate much, no correction is necessary.
[0031]
【The invention's effect】
As described above, according to the present invention, the configuration of the electronic ballast of the high-intensity discharge lamp allows the input current to be a sine wave by operating the buck-boost chopper circuit in the current reset mode / fixed time ratio. In addition, by supplying constant power to the output and operating the bridge inverter in the subsequent stage at a low frequency, stable power is supplied to the discharge lamp as a load. With about the number of parts, the input current can be made sinusoidal and the harmonics can be greatly reduced.
[Brief description of the drawings]
FIG. 1 shows a first embodiment of an electronic lighting device for a discharge lamp according to the present invention.
FIG. 2 is a current waveform diagram for explaining the operation of the embodiment shown in FIG. 1;
FIG. 3 shows a second embodiment of an electronic lighting device for a discharge lamp according to the present invention.
FIG. 4 shows a third embodiment of the electronic lighting device for a discharge lamp according to the present invention.
FIG. 5 shows a fourth embodiment of an electronic lighting device for a discharge lamp according to the present invention.
FIG. 6 shows a fifth embodiment of the electronic lighting device for a discharge lamp according to the present invention.
FIG. 7 shows a sixth embodiment of an electronic lighting device for a discharge lamp according to the present invention.
FIG. 8 shows a seventh embodiment of the electronic lighting device for a discharge lamp according to the present invention.
FIG. 9 is a waveform diagram of a discharge lamp current and the like.
FIG. 10 is an example of a conventional electronic lighting device for a discharge lamp.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... High frequency filter 2 ... Rectifier circuit 3 ... Buck-boost type converter circuit
4 ... Inverter circuit 5 ... Discharge lamp 6 ... Calculation control circuit 7 ... Drive circuit
8 ... Inverse proportional circuit 9 ... Square circuit 10 ... Voltage controlled oscillator 11 ... Monostable circuit
DESCRIPTION OF SYMBOLS 12 ... Synchronous oscillation circuit 13 ... Sine wave generation circuit 15 ... Discharge lamp lighting confirmation circuit
16 ... Bridge / double voltage switching rectifier circuit
CL4 ... Comparator CT, CT4 ... Current transformer Er1 ... Reference voltage
L ... Inductance for buck-boost OA1 ... Amplifier MP ... Multiplier RL ... Relay

Claims

A pair of input terminals connected to a commercial AC power source;
A rectifier circuit connected to the pair of input terminals and converting to a pulsating flow;
A step-up / step-down converter circuit connected to the pulsating flow output of the rectifying circuit, comprising a switching element that switches at a frequency sufficiently higher than the frequency of the pulsating flow, a step-up / step-down inductance means, and a rectifying circuit. A step-up / down converter circuit that discharges all energy accumulated in the step-up / step-down inductance means during the ON period of the switching element to the output side during the OFF period;
The switching element of the step-up / step-down converter circuit is operated at a fixed frequency, and the commercial AC voltage is operated at a fixed time ratio for a period of at least one cycle, and is inversely proportional to the average value of the input voltage of the step-up / step-down converter circuit. There rows duty ratio control of the switching element as an arithmetic control circuit for controlling the output of the buck-boost converter circuit to maintain constant power,
An inverter circuit connected to the output of the step-up / step-down converter circuit for converting into an alternating voltage having a constant frequency;
A pair of output terminals connected to the output of the inverter circuit to supply power to the discharge lamp;
An electronic lighting device for a discharge lamp.

A pair of input terminals connected to a commercial AC power source;
A rectifier circuit connected to the pair of input terminals and converting to a pulsating flow;
A step-up / step-down converter circuit connected to the pulsating flow output of the rectifying circuit, comprising a switching element that switches at a frequency sufficiently higher than the frequency of the pulsating flow, a step-up / step-down inductance means, and a rectifying circuit. A step-up / down converter circuit that discharges all energy accumulated in the step-up / step-down inductance means during the ON period of the switching element to the output side during the OFF period;
The switching element of the buck-boost converter circuit is operated at a fixed on-time, and is operated at a fixed time ratio for at least one cycle of the commercial AC voltage, and the square of the average value of the input voltage of the buck-boost converter circuit An operation control circuit that controls the operation cycle of the switch element in proportion to the control element and controls the output of the step-up / down converter circuit to maintain a constant power;
An inverter circuit connected to the output of the step-up / step-down converter circuit for converting into an alternating voltage having a constant frequency;
A pair of output terminals connected to the output of the inverter circuit to supply power to the discharge lamp;
An electronic lighting device for a discharge lamp.

A pair of input terminals connected to a commercial AC power source;
A rectifier circuit connected to the pair of input terminals and converting to a pulsating flow;
A step-up / step-down converter circuit connected to the pulsating flow output of the rectifying circuit, comprising a switching element that switches at a frequency sufficiently higher than the frequency of the pulsating flow, a step-up / step-down inductance means, and a rectifying circuit. A step-up / down converter circuit that discharges all energy accumulated in the step-up / step-down inductance means during the ON period of the switching element to the output side during the OFF period;
A voltage generation circuit for generating a sine wave synchronized with an input voltage waveform of the step-up / down converter circuit; operating a switching element of the step-up / down converter circuit at a fixed frequency; and outputting a voltage output from the voltage generation circuit as a current An arithmetic control circuit that performs a control to turn off the switching element when the current of the switching element reaches the current reference signal as a reference signal ;
An inverter circuit connected to the output of the step-up / step-down converter circuit for converting into an alternating voltage having a constant frequency;
A pair of output terminals connected to the output of the inverter circuit to supply power to the discharge lamp;
An electronic lighting device for a discharge lamp.

A series circuit of a resistor and a first capacitor is connected between the output terminals of the buck-boost converter circuit, a bridge inverter circuit is connected to the output of the first capacitor, and the output of the bridge inverter circuit is the first connect the load second capacitor, the said bridge inverter circuit, a means for detecting that the current flows from claim 1, characterized in that short-circuiting the resistor by a signal of the detection means 3 An electronic lighting device for a discharge lamp according to any one of the above.

5. The correction circuit according to claim 1, wherein the step-up / step-down converter circuit is provided with a correction means for narrowing a conduction width of the switching element as the average value rises with respect to fluctuations in the average value of the input voltage. The electronic lighting device for discharge lamps in any one.

The buck-boost converter circuit discharge lamp electronic lighting device according to any one of claims 1-5, characterized in that the non-isolated.

The electronic lighting device for a discharge lamp according to any one of claims 1 to 6 , wherein the step-up / step-down converter circuit is an insulating type.