JP4161436B2 - Inverter device - Google Patents

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Publication number
JP4161436B2
JP4161436B2 JP34509198A JP34509198A JP4161436B2 JP 4161436 B2 JP4161436 B2 JP 4161436B2 JP 34509198 A JP34509198 A JP 34509198A JP 34509198 A JP34509198 A JP 34509198A JP 4161436 B2 JP4161436 B2 JP 4161436B2
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Japan
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conduction ratio
power switching
output
rotational speed
switching means
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JP2000175476A (en
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英樹 両角
和彦 麻田
秀和 山下
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Panasonic Corp
Panasonic Holdings Corp
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Panasonic Corp
Matsushita Electric Industrial Co Ltd
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  • Control Of Ac Motors In General (AREA)
  • Control Of Motors That Do Not Use Commutators (AREA)

Description

【０００１】
【発明の属する技術分野】
本発明は、一般家庭で使用される電気機器に備えたインバ−タ装置に関するものである。
【０００２】
【従来の技術】
従来の電動機の回転子に永久磁石を有するインバ−タ装置においては、前記電動機の出力トルクを一定に抑えるために電流検出器と電流制御手段を設け、前記電流検出器が前記電動機の三相巻線に流れる電流や、前記インバ−タ装置を構成するパワ−スイッチング手段に流れる電流を検知し、前記電流制御手段が前記電流検出器の出力を受けて所定の電流値になるように、前記パワ−スイッチング手段の導通比を制御するものであった。
【０００３】
【発明が解決しようとする課題】
しかしながら、前記従来のインバ−タ装置においては、電動機の出力トルクを一定以下に抑えるために、電流検出器と電流制御手段を設け、フィ−ドバック制御を行う必要があり、前記インバ−タ装置の構成が複雑になる問題を有していた。
【０００４】
また、電流制御手段の制御方式やパワ−スイッチング手段の導通比の操作量によっては、電動機の起動時に所定の電流値に対するオ−バ−シュ−トが発生し、三相巻線やパワ−スイッチング手段に過電流が流れたり、電動機の出力軸に過大なトルクがかかるなどして故障の原因になる問題も有していた。
【０００５】
本発明は上記従来のインバ−タ装置の課題を解決するものであり、電動機の回転数に応じて、パワ−スイッチング手段の導通比の最大値を設定することで、電流検出器や電流制御手段を設けなくても、確実にパワ−スイッチング手段や電動機の三相巻線に流れる電流を一定以下に抑え、そして電動機の出力トルクを一定以下に抑えることを目的としている。
【０００６】
【課題を解決するための手段】
上記課題を解決するために本発明は、交流電源と、前記交流電源を直流電源に変換する整流回路と、前記整流回路の出力する直流電源を交流電源に変換するインバ−タ回路と、前記インバ−タ回路の出力側に接続し、回転子に永久磁石を有する電動機と、前記インバ−タ回路を構成するパワ−スイッチング手段をオンオフ制御する制御手段と、前記電動機の回転子の回転数を検知する回転数検知手段と、前記回転数検知手段の出力を受けて前記パワ−スイッチング手段の導通比を制御する導通比制御手段と、前記導通比制御手段の出力する導通比の最大値を制御する導通比制限手段を備え、前記導通比制限手段は前記回転数検知手段の出力が小なら小、大なら大に、導通比の最大値を設定し、電流を一定以下に抑え過電流を防止するように構成したものである。
【０００７】
これにより、電動機を構成する三相巻線やインバ−タ回路に流れる電流を検知することなく、前記電流を一定以下に抑え、電動機の出力トルクを一定以下に抑えることができ、比較的簡単な構成で安全なインバ−タ装置を実現できる。
【０００８】
【発明の実施の形態】
本発明の請求項１に記載の発明は、交流電源と、前記交流電源を直流電源に変換する整流回路と、前記整流回路の出力する直流電源を交流電源に変換するインバ−タ回路と、前記インバ−タ回路の出力側に接続し、回転子に永久磁石を有する電動機と、前記インバ−タ回路を構成するパワ−スイッチング手段をオンオフ制御する制御手段と、前記電動機の回転子の回転数を検知する回転数検知手段と、前記回転数検知手段の出力を受けて前記パワ−スイッチング手段の導通比を制御する導通比制御手段と、前記導通比制御手段の出力する導通比の最大値を制御する導通比制限手段を備え、前記導通比制限手段は前記回転数検知手段の出力が小なら小、大なら大に、導通比の最大値を設定し、電流を一定以下に抑え過電流を防止するように構成したものである。
【０００９】
この構成によれば、回転数検知手段の出力に応じてインバ−タ回路の導通比の最大値を設定する電導通比制限手段によって、電動機を構成する三相巻線やインバ−タ回路に流れる電流を検知することなく、前記電流を一定以下に抑え、そして電動機の出力トルクを一定以下に抑えられるのである。
【００１０】
また本発明の請求項２に記載の発明は、請求項１記載の発明において、整流回路の出力する直流電圧を検知する電圧検知手段を備え、導通比制限手段は前記電圧検知手段の出力を受けて、パワ−スイッチング手段の導通比の最大値を補正するように構成したものである。
【００１１】
この構成によれば、電圧検知手段の出力を受けて、パワ−スイッチング手段の導通比の最大値を補正する導通比制限手段によって、交流電源の電圧変動等により整流回路の出力電圧が変動しても、電動機の三相巻線に流れる電流を検知することなく、前記電流を一定以下に抑え、そして電動機の出力トルクを一定以下に抑えられるのである。
【００１２】
本発明の請求項３に記載の発明は、請求項１または２記載の発明において、導通比制限手段は、回転数検知手段が検知した検知回転数の範囲に応じてパワ−スイッチング手段の導通比の最大値を設定する構成にしたものである。
【００１３】
この構成によれば、回転数検知手段が検知した検知回転数の範囲に応じてパワ−スイッチング手段の導通比の最大値を設定する導通比制限手段によって、簡単な構成で電動機の出力トルクを一定以下に抑えることが可能になり、安価なインバ−タ装置を実現できる。
【００１４】
また本発明の請求項４に記載の発明は、請求項１〜３のいずれか１項に記載の発明のおいて、電動機の起動時には、導通比制限手段によりパワ−スイッチング手段の導通比を制御し、その後は導通比制御手段によりパワ−スイッチング手段の導通比を制御する構成にしたものである。
【００１５】
この構成によれば、電動機の起動時にはパワ−スイッチング手段の導通比を導通比制限手段が制御し、電動機の起動後はパワ−スイッチング手段の導通比を導通比制御手段が制御するので、電動機の三相巻線の電流に相当する電流を検知することなく、電動機の出力トルクを可能な限り大きくして回転することができる。従って、電動機の出力トルクが過大にならない状態で電動機を目標回転数まで短時間で立ち上げることができる。
【００１６】
本発明の請求項５に記載の発明は、請求項１〜３のいずれか１項に記載の発明において、電動機の起動時には、パワ−スイッチング手段の導通比を所定値より増加させ、その後導通比制御手段によりパワ−スイッチング手段の導通比を制御する構成にしたものである。
【００１７】
この構成によれば、電動機の起動時にはパワ−スイッチング手段の導通比を所定値より増加させ、電動機の起動後はパワ−スイッチング手段の導通比を導通比制御手段により制御するので、電動機の低速時に回転数検知手段による回転数検知の確定までの時間が長くなるような場合においても、パワ−スイッチング手段の導通比を一方的に設定していくので、電動機を目標回転数まで比較的高速に立ち上げることができる。また、電動機の起動時にはパワ−スイッチング手段の導通比を電動機の出力トルクが過大にならない範囲に設定することで、電動機の出力軸の破損を防止できる安全なインバ−タ装置を実現できる。
【００１８】
本発明の請求項６に記載の発明は、請求項１〜３のいずれか１項に記載の発明において
、電動機の起動時にはパワ−スイッチング手段の導通比を所定値より増加させ、その後は導通比制限手段によりパワ−スイッチング手段の導通比を制御し、さらにその後は導通比制御手段によりパワ−スイッチング手段の導通比を制御する構成にしたものである。
【００１９】
この構成によれば、電動機の低速時における回転数検知が必要なくなり、また回転数検知が可能な回転数領域から導通比制限手段により電動機の出力トルクを可能な限り大きくして回転することができる。従って、回転数検知手段が電動機の低速における回転数を検知する時間が長くても、電動機を目標回転数まで短時間かつ安全に立ち上げることができる。
【００２０】
【実施例】
以下、本発明の実施例について図面を参照しながら説明する。
【００２１】
（実施例１）
実施例１は本発明インバ−タ装置の請求項１に記載の発明の一実施例で、そのブロック回路構成を図１が示すものである。このインバ−タ装置は、交流電源１に整流回路２を接続し、この整流回路２の高電位側出力端子にはインバ−タ回路３を接続し、さらにインバ−タ回路３の出力端子には電動機４を接続して構成している。
【００２２】
整流回路２はダイオ−ドブリッチ２ａと２個のコンデンサ２ｂ，２ｃの直列回路により倍電圧整流回路を構成しているが、特にこれに限定されるものではなく、ダイオ−ドブリッチと１個のコンデンサにより全波整流回路の構成にしてもよい。
【００２３】
インバ−タ回路３は６個のパワ−スイッチング手段３ａ〜３ｆにより三相六石の構成にしている。そして、パワ−スイッチング手段３ａ〜３ｆは高周波スイッチングと大電流容量に対応できるＩＧＢＴと逆接続のダイオ−ドの並列回路で構成しているが、特にこれに限定されるものではなくサイリスタやＭＯＳＦＥＴ等を用いてもよい。また、インバ−タ回路３の構成についても三相六石に限定されるものではなく、三相三石等にしてもよい。
【００２４】
電動機４は固定子に三相巻線４ａを形成した電機子巻線を有し、かつ回転子に永久磁石を有する直流ブラシレスモ−タを採用している。そして、電動機４は回転子４ｂの極数を４極にしているが、特にこれに限定されるものではない。
【００２５】
制御手段５はＰＷＭ回路５ａと三相分配回路５ｂと駆動回路５ｃ等からなり、これら回路はマイクロコンピュ−タや論理回路等により構成されている。ＰＷＭ回路５ａは、前記マイクロコンピュ−タ内のカウンタとマグニチュ−ドコンパレ−タにより構成され、約１５．７ｋＨｚでハイ、ロ−の各信号を交互に駆動回路５ｃに出力する。そして、ＰＷＭ回路５ａは後述する導通比制限手段９の出力値と前記カウンタの出力値をマグニチュ−ドコンパレ−タが比較し、導通比制限手段９の出力値に応じた期間、ハイの信号を駆動回路５ｃに出力する。三相分配回路５ｂは後述する電動機４の回転子４ｂの位置を検出する位置検知手段６の出力に応じてパワ−スイッチング手段３ａ〜３ｆのオンオフの組合せを設定し、駆動回路５ｃに出力する。駆動回路５ｃはＰＷＭ回路５ａと三相分配回路５ｂの出力を受けて、所望のパワ−スイッチング手段を設定導通比でオンオフ制御し、電動機４に交流電力を供給し、電動機４が回転するようにしている。
【００２６】
位置検知手段６は１２０度の電気角で配置された３個のホ−ルＩＣ６ａ〜６ｃからなり、回転子４ｂの永久磁石の対向する表面がＳ極である場合にはハイを、Ｎ極である場合にはロ−の各信号を制御手段５に出力するようにしている。そして、詳細に後述するが、このホ−ルＩＣ６ａ〜６ｃの前記出力の組合せを受けて制御手段５がパワ−スイッチング手段３ａ〜３ｆをオンオフ制御する。なお、本実施例でホ−ルＩＣ６ａ〜６ｃの配置は一例であり、例えばホ−ルＩＣ６ａ〜６ｃの内の１個を電気角で１８０度移動し、そのホ−ルＩＣの論理を回転子４ｂの永久磁石の対向する表面がＳ極である場合にはロ−を、Ｎ極である場合にはハイの各信号を制御手段５に出力するようにしてもよい。また、位置検知手段６においても、ホ−ルＩＣによる構成に限定されるものではなく、電動機４の三相巻線４ａの各相巻線に発生する誘起電圧を検知し、この検知信号に基づいて回転子４ｂの永久磁石の位置を検知してもよいし、フォトインタラプタ等で光学的に位置検出を行ってもよい。
【００２７】
７は位置検知手段６の出力側に接続した回転数検知手段で、８は回転数検知手段７の出力側に接続した導通比制御手段で、９は回転数検知手段７と導通比制御手段８の出力側に接続した導通比制限手段で、これらはマイクロコンピュ−タで構成されている。
【００２８】
回転数検知手段７はホ−ルＩＣ６ａがハイの信号を出力している期間をマイクロコンピュ−タ内のカウンタにより検知し、その期間により回転子４ｂの回転数Ｎｉｎを判定している。そして、この回転数検知方法は一例であり、ホ−ルＩＣ６ａの出力を積分回路に通し、電圧値として検知することも可能であるし、またそれとは別に制御の安定性を得るために所定期間内におけるホ−ルＩＣのハイの信号出力時間をカウンタを用いて検知してもよい。
【００２９】
導通比制御手段８は回転数検知手段７の検知した回転子４ｂの検知回転数Ｎｉｎと目標回転数Ｎｓを入力し、この二つの入力値に応じてパワ−スイッチング手段３ａ〜３ｆの導通比設定値ｄｓを導通比制限手段９に出力する。本実施例においては、比例成分（Ｐ成分）により回転数制御の安定性、応答性を高めるとともに、積分成分（Ｉ成分）を用いて目標回転数Ｎｓに対する定常偏差を０にする比例積分（ＰＩ）制御を行っている。ただ、この制御方式については比例積分制御に限定されるものではなく、比例成分、積分成分の他に応答速度を高めるために微分成分（Ｄ成分）を構成要素に取り入れたＰＩＤ制御や比例制御やファジイ制御を用いてもよい。また、マイクロコンピュ−タの性能によっては導通比制御手段８をオペアンプ等で構成しても構わない。
【００３０】
導通比制限手段９は詳細に後述するが、回転数検知手段７の検知した回転子４ｂの検知回転数Ｎｉｎが入力され、この検知回転数Ｎｉｎに応じた導通比の最大値ｄｍａｘを設定する。一方、導通比制御手段８より導通比設定値ｄｓが導通比制限手段９に入力されると、この導通比制限手段９において先に設定された導通比最大値ｄｍａｘと導通比設定値ｄｓを比較し、導通比の小さい方を制御手段５に出力する。そして、制御手段５は位置検知手段６によりパワ−スイッチング手段３ａ〜３ｆのオンオフを設定し、オンを設定したパワ−スイッチング手段を導通比制限手段９により出力された導通比でオンオフ制御をする。なお、本実施例においては図５に示すグラフの導通比最大値ｄｍａｘと検知回転数Ｎｉｎの関係を予めマイクロコンピュ−タ内に設定しているものである。
【００３１】
以上のように、回転子４ｂの回転数を検知するごとに、導通比制限手段９によりパワ−スイッチング手段の導通比の最大値を設定することで、電動機４の三相巻線４ａへの印加電圧を所定値以下にすることができるので、検知回転数Ｎｉｎ以上において三相巻線４ａに流れる電流を所定値以下に抑えることができ、電動機４の出力トルクを所定値以下に抑えることができる。ただし、本実施例における回路構成や電動機の構成は一例であり、他の構成にしてもよいものである。
【００３２】
図２は図１のインバ−タ装置における各部の信号の波形（ａ）〜（ｌ）を示すものである。波形（ａ）〜（ｃ）は位置検知手段６のホ−ルＩＣ６ａ〜６ｃの出力波形である。この信号のうち、回転数検知手段７はホ−ルＩＣ６ａの出力信号を検知しており、ホ−ルＩＣ６ａのハイ信号の期間を検知することで、その期間に応じた電動機４の回転数を導通比制御手段８と導通比制限手段９に出力している。また、三相分配回路５ｂは位置検知手段６の出力信号の論理に応じて、図２の波形（ｄ）〜（ｉ）のようにパワ−スイッチング手段３ａ〜３ｆのオンオフを組み合わせて出力する。波形（ｄ）はパワ−スイッチング手段３ａのオンオフ状態、波形（ｅ）はパワ−スイッチング手段３ｂのオンオフ状態、波形（ｆ）はパワ−スイッチング手段３ｃのオンオフ状態、波形（ｇ）はパワ−スイッチング手段３ｄのオンオフ状態、波形（ｈ）はパワ−スイッチング手段３ｅのオンオフ状態、波形（ｉ）はパワ−スイッチング手段３ｆのオンオフ状態を示している。そして、パワ−スイッチング手段３ａ〜３ｆはいずれも三相のＵ、Ｖ、Ｗの相切り替えのタイミングに同期して、前半をＰＷＭ回路５ａの出力信号に同期してパワ−スイッチング手段をオンオフ制御している。これにより、パワ−スイッチング手段３ａ〜３ｆによる三相巻線４ａの相切り替え時に発生する騒音を低減することができる。また、この時のＰＷＭ回路５ａが出力するオン期間とオフ期間の比、すなわちパワ−スイッチング手段のオン期間とオフ期間の比は導通比制御手段８および導通比制限手段９により設定される導通比に応じた値となっている。そして、制御手段５により、いずれかの二つのパワ−スイッチング手段がオンされると電動機４の二つの入力端子に電圧が印加され、この印加電圧と電動機４の回転子４ｂの回転による誘起電圧の差分の電圧により、（ｊ）〜（ｌ）のような相電流が流れる。なお、この相電流（ｊ）〜（ｌ）はパワ−スイッチング手段３ａ〜３ｃがオンした時に流れる電流を正方向にしている。
【００３３】
図３は本実施例の直流ブラシレスモ−タで構成された電動機４の三相巻線４ａに流れる電流のピ−ク値と出力トルクの関係を示すグラフである。図３に示したように直流ブラシレスモ−タでは、三相巻線４ａに流れる電流にトルク定数Ｋｔを乗じたものが出力トルクとなる。
【００３４】
以上のように直流ブラシレスモ−タにおいては、三相巻線４ａに流れる電流のピ−ク値と出力トルクは殆ど比例関係となる。
【００３５】
図４は本実施例の直流ブラシレスモ−タにおいて、パワ−スイッチング手段３ａ〜３ｆの導通比ごとの回転数と出力トルクの関係を示すグラフである。なお、この時の交流電源１の入力電圧はＡＣ１００Ｖで、整流回路２の出力する直流電圧が約２８２Ｖになるようにしている。グラフ（ア）はパワ−スイッチング手段３ａ〜３ｆの導通比が１００％の時の特性である。グラフ（イ）はパワ−スイッチング手段３ａ〜３ｆの導通比が７５％の時の特性である。グラフ（ウ）はパワ−スイッチング手段３ａ〜３ｆの導通比が５０％の時の特性である。グラフ（エ）はパワ−スイッチング手段３ａ〜３ｆの導通比が２５％の時の特性である。図４を見ても明らかなように出力トルクＴｓになる回転数は導通比により異なっている。図４の場合には、導通比１００％においては回転数Ｎ１で出力トルクがＴｓになり、導通比７５％においては回転数Ｎ２で出力トルクがＴｓになり、導通比５０％においては回転数Ｎ３で出力トルクがＴｓになり、導通比２５％においては回転数Ｎ４で出力トルクがＴｓになっている。従って、回転子４ｂの回転数に応じてパワ−スイッチング手段３ａ〜３ｆの導通比最大値ｄｍａｘを設定することで電動機４の出力トルクを一定以下に抑えることができる。
【００３６】
一般的に直流ブラシレスモ−タにおいては、永久磁石を有する回転子４ｂの回転数に、誘起電圧定数を乗じたものが誘起電圧となり、この誘起電圧と三相巻線４ａへの印加電圧の差分の電圧により三相巻線４ａに電流が供給され、この電流によりトルクを発生するものである。また、三相巻線４ａの印加電圧はパワ−スイッチング手段３ａ〜３ｆの導通比を制御することで制御可能である。本実施例においては、整流回路２の出力する直流電圧にパワ−スイッチング手段３ａ〜３ｆの導通比を乗じたものが印加電圧となる。
【００３７】
従って、導通比制限手段９によりパワ−スイチング手段３ａ〜３ｆの導通比の最大値を制限することで、三相巻線４ａへの印加電圧の最大値を制限できるので、図４のグラフ（ア）〜（エ）のように回転数と出力トルクの関係を制御できるようになる。これは先に説明したが、直流ブラシレスモ−タにおいては三相巻線４ａへの印加電圧と回転子４ｂの回転により生じる誘起電圧の差分の電圧に応じて三相巻線４ａに電流が流れ、この電流にトルク定数Ｋｔを乗じた値が出力トルクになる特性を有するためである。
【００３８】
図５は本実施例のインバ−タ装置の導通比制限手段９に予め設けた回転子４ｂの検知回転数Ｎｉｎとパワ−スイッチング手段３ａ〜３ｆの導通比最大値ｄｍａｘの関係を示すグラフの一例である。本実施例においては、導通比制限手段９は導通比最大値ｄｍａｘと検知回転数Ｎｉｎを連続的な関数になるようにしており、検知回転数Ｎｉｎを入力するごとに導通比最大値ｄｍａｘを演算している。しかしながら、特に関数を設けて検知回転数Ｎｉｎの入力ごとに導通比最大値ｄｍａｘを演算する必要はなく、検知回転数Ｎｉｎに応じて導通比最大値ｄｍａｘをマイクロコンピュ−タ内のメモリに記憶しておき、検知回転数Ｎｉｎの入力ごとに、入力された検知回転数Ｎｉｎに応じた導通比最大値ｄｍａｘを設定してもよい。
【００３９】
図６は図５のようにパワ−スイッチング手段３ａ〜３ｆの導通比最大値ｄｍａｘを設定した場合の電動機４の回転数Ｎと出力トルクＴの関係を示すグラフである。図５において回転子４ｂの回転数に応じて、パワ−スイッチング手段３ａ〜３ｆの導通比最大値ｄｍａｘを設けたことにより、前記回転数に応じた三相巻線４ａへの最大印加電圧が決定し、その結果、電動機４の回転数に応じた最大出力トルクも制限され、図６に示した特性になるものである。
【００４０】
以上のように、電動機４の回転数に応じてパワ−スイッチング手段３ａ〜３ｆの導通比最大値ｄｍａｘを設けることにより、電動機４の三相巻線４ａの印加電圧が制限され、そして三相巻線４ａに流れる電流も制限され、その結果、電動機４の出力トルクは制限される。従って、三相巻線４ａやパワ−スイッチング手段３ａ〜３ｆの電流を検知することなく、三相巻線４ａやパワ−スイッチング手段３ａ〜３ｆに過電流が流れるのを防止できるとともに、電動機４の出力軸にも過大なトルクがかかるのを防止できる。また、本実施例においては回転子４ｂの回転数を検知してから導通比最大値ｄｍａｘを設定することにより、電動機４の回転数が上昇していくような起動時の場合には、三相巻線４ａに生じる誘起電圧が大きくなり、三相巻線４ａに流れる電流が小さくなっていくので、電動機４の最大出力トルクを越えることがなくなり、電動機４の三相巻線４ａやインバ−タ回路３の構成部品に過電流が流れることのない安全なインバ−タ装置を実現できる。
【００４１】
上記実施例において、インバ−タ装置における電動機４の回転数制御を図７に示すステップ１１〜ステップ１７（以下Ｓ１１、Ｓ１２、Ｓ１３・・という）のフロ−チャ−トに従い説明する。Ｓ１１において電動機４の回転数制御サブル−チンを開始すると、Ｓ１２で回転数検知手段７により電動機４の回転数を検知し、導通比制御手段８および導通比制限手段９に検知回転数Ｎｉｎを出力する。Ｓ１３では導通比制御手段８は検知回転数Ｎｉｎと予め設定された目標回転数Ｎｓにより、比例積分制御を行い導通比設定値ｄｓを導通比制限手段９に出力する。Ｓ１４では導通比制限手段９が予め設定された図５に示すグラフに基づき検知回転数Ｎｉｎに応じた導通比最大値ｄｍａｘを設定し、Ｓ１５で導通比制限手段９が導通比設定値ｄｓと導通比最大値ｄｍａｘを比較し、導通比設定値ｄｓが導通比最大値ｄｍａｘより大きい場合は、Ｓ１６で導通比最大値ｄｍａｘを導通比として制御手段５に出力する。また、Ｓ１５で導通比設定値ｄｓが導通比最大値ｄｍａｘより小さい場合は、Ｓ１７で導通比設定値ｄｓを導通比として制御手段５に出力する。そして、前記の各導通比で制御手段５がパワ−スイッチング手段３ａ〜３ｆをオンオフ制御する。その後、再びＳ１２にて回転数検知手段７により電動機４の回転数を検知し、上記制御した制御を繰り返すものである。
【００４２】
以上のように、導通比制限手段９を設けることで、電動機４の三相巻線４ａの電流やインバ−タ回路３に流れる電流を検知しなくても、前記電流の最大値を制御することができる。従って、電動機４の出力トルクも一定に抑えることができる。
【００４３】
図８は本実施例におけるインバ−タ装置を備えた電気洗濯機の構造図を示している。２１は水受け槽で、攪拌翼２２を内定部に回転自在に有する洗濯兼脱水槽２３を内側に回転自在に設け、さらに全体を支持棒２４により洗濯機本体２５内につり下げている。２６は水受け槽２１の外底部に設けた減速機構で、下部に設けた電動機４の動力を攪拌翼２２および洗濯兼脱水槽２３に伝達するものである。そして、減速機構２６は遊星歯車を有し、攪拌翼２２を回転駆動する際には、太陽歯車を電動機４の出力軸によって駆動し、遊星歯車の回転を攪拌翼２２に伝達する構成にすることにより、１／６に減速するとともに電動機４の出力トルクを６倍に変換する。また、脱水などの洗濯兼脱水槽２３を回転駆動する制御においては、特に図示していないがクラッチにより減速機構２６を電動機４の出力軸より切り離し、洗濯兼脱水槽２３を電動機４の出力軸で直接に回転駆動する。２７は洗濯兼脱水槽２３に給水をする給水弁、２８は洗濯兼脱水槽２３内の洗濯水を排水する排水弁である。
【００４４】
上記電気洗濯機の動作を説明する。洗濯兼脱水槽２３内に洗濯物と洗剤を使用者が投入した状態で運転を開始すると、給水弁２７を開き水道水を水受け槽２１内に入れて所定水位まで上昇させ、攪拌翼２２を回転させて洗浄を行う。この洗浄においては、クラッチにより洗濯兼脱水槽２３と電動機４の出力軸を切り離すとともに、減速機構２６と電動機４の出力軸を接続し、電動機４の回転数を１／６に減速して攪拌翼２２を回転させる。この時図１における制御手段５は電動機４が正転、反転を繰り返すように電動機４を制御する。そして、攪拌翼２２による洗浄が終了すると、排水弁２８を開き、水受け槽２１内の洗浄水を排水する。その後に電動機４の出力軸と洗濯兼脱水槽２３を直結させ、洗濯兼脱水槽２３を電動機４により直接回転させ、洗濯物に含まれた洗浄液を脱水する。
【００４５】
続いて洗濯物のすすぎ工程が行われるが、上記した洗浄時の動作と同じようにすすぎ水の給水とともに減速機構を介して攪拌翼２２を電動機４により回転させて行われる。
【００４６】
さらに脱水工程では、排水弁２８を開いて水受け槽２１内のすすぎ水を排水し、クラッチにより洗濯兼脱水槽２３と電動機４を直結し、洗濯兼脱水槽２３を電動機４により９００ｒｐｍで回転させ、これにより遠心力で洗濯物の脱水を行う。
【００４７】
以上のように図８に示す電気洗濯機は電動機４を回転させて洗濯物を洗濯脱水するものであり、電動機４の回転制御はインバ−タ回路３、制御手段５、導通比制御手段８、導通比制限手段９からなる本発明のインバ−タ装置により行われる。ここで図１の説明で述べたように、導通比制御手段８は目標回転数Ｎｓと回転数検知手段７が検知した検知回転数Ｎｉｎを入力し、比例積分制御によりパワ−スイッチング手段３ａ〜３ｆの導通比を設定して目標回転数Ｎｓまで回転数を上昇させ、目標回転数Ｎｓで安定させる。しかしながら、例えば、攪拌翼２２による洗浄時に攪拌翼２２を回転させたことにより洗濯物が絡まり、攪拌翼２２にかかる負荷が急に増加した状態で、電動機４が減速機構２６を介して攪拌翼２２を回転させようとすると、導通比制御手段８は回転数を上昇させるため前記導通比を増加させるために、三相巻線４ａやインバ−タ回路３に過電流が流れ電動機４の出力軸にかかるトルクが過大になったり、パワ−スイッチング手段３ａ〜３ｆの定格電流を越えたりすることになる。
【００４８】
そこで、本発明では図１の説明で述べたように導通比制限手段９が回転数検知手段７が検知した検知回転数Ｎｉｎに応じた導通比最大値ｄｍａｘを設定することで、三相巻線４ａやインバ−タ回路３に流れる電流を一定に抑えながら電動機４の回転数を上昇させていくことができる。従って、電動機４の出力トルクを一定以下に抑えながら、電動機４の回転数を上昇させることができる。
【００４９】
以上のように、導通比制限手段９を設けることにより、特に電流検知手段や電流制御手段を設けなくても、三相巻線４ａやインバ−タ回路３に流れる電流を一定に抑え、かつ電動機４の出力トルクを一定に抑えながら電動機４の回転数を制御することが可能になる。従って、三相巻線４ａやインバ−タ回路３が過電流により故障したり、電動機４の出力軸に過大なトルクがかかり前記出力軸が破損したりするのを防止することができる。なお、本実施例においては攪拌翼２２を減速機構２６を介して電動機４により回転駆動する例を示しているが、電動機４により洗濯兼脱水槽２３を直接駆動する場合においても同様に導通比制限手段９により出力トルクを一定以下に抑えながら電動機４を回転制御できるものである。特に水受け槽２１に水を入れた状態で洗濯兼脱水槽２３を電動機４により直接回転駆動し、遠心力により水を洗濯物に通過させて洗浄するような方式の電気洗濯機においては、大トルクが必要になるが、本実施例のように導通比制限手段９によって検知回転数Ｎｉｎに応じて導通比最大値ｄｍａｘを制御することで、電動機４の出力トルクを一定以下に抑えながら起動することができ、三相巻線４ａやインバ−タ回路３に過電流が流れるのを、そして電動機４の出力軸にかかるトルクが過大になるのをそれぞれ防止することができる。
【００５０】
また、本実施例においては特に図示していないが、低電位側のパワ−スイッチング手段３ａ〜３ｆがオン状態の期間に、例えばスイッチング電源等で構成された直流電源より、ダイオ−ドや充電抵抗を介してコンデンサに充電し、これを高電位側のパワ−スイッチング手段３ａ〜３ｃの駆動電源として使用しているインバ−タ装置においても、電動機４の低速時に導通比制限手段９によりパワ−スイッチング手段３ａ〜３ｆの導通比最大値ｄｍａｘを制限することで、確実にパワ−スイッチング手段３ａ〜３ｃのオフ期間が設けられ、高電位側のパワ−スイッチング手段３ａ〜３ｃの駆動電源の充電期間が得られるので、前記駆動電源を構成するブ−トストラップコンデンサが放電され電位が低下し、パワ−スイッチング手段３ａ〜３ｃがオンできないようになり、電動機４が起動しないという異常を防止することができる。
【００５１】
また図８に示した電気洗濯機のように、減速機構２６を介して電動機４の出力トルクを負荷に伝達するような機器においては、電動機４の出力軸だけでなく、減速機構２６の構成部品が電動機４の出力トルクが過大になることで破損する可能性を生じる。この場合には導通比制限手段９に図５で示した回転数−導通比最大値の設定グラフとは別の設定がされたグラフを設けておくことにより、減速機構２６の保護をしながら電動機４の回転駆動をすることができる。従って、電動機の回転数−導通比最大値の設定テ−ブルを複数設けておくことにより、複数の保護対象を有する機器においても、電動機４の出力トルクが過大にならないように回転駆動することができる。
【００５２】
（実施例２）
実施例２は本発明のインバ−タ装置における導通比制限手段が、実施例１における図１に示した導通比制限手段９と異なるだけで、それ以外の構成および作用効果は実施例１と同じなので詳細な説明は省略し、異なる部分を中心に図１を利用して説明する。すなわち、実施例２における導通比制限手段９は、回転数検知手段７の出力する検知回転数Ｎｉｎとパワ−スイッチング手段３ａ〜３ｆの導通比最大値ｄｍａｘの関係を図９に示した関係になるようにテ−ブルを予め設定している。
【００５３】
上記実施例について図９に従い説明する。検知回転数Ｎｉｎを予め８個の範囲Ｎａ〜Ｎｈに分割し、各範囲ごとに前記導通比最大値ｄｍａｘが設定されている。そして、導通比制限手段９は回転数検知手段７が回転子４ｂの回転数を検知するごとに検知回転数Ｎｉｎが入力され、検知回転数の範囲Ｎａ〜Ｎｈのいずれの範囲に入るかを判定し、導通比最大値ｄｍａｘを設定する。その後、導通比制御手段８の出力した導通比設定値ｄｓと導通比最大値ｄｍａｘを比較し、導通比の小さい方を制御手段５に入力する。
【００５４】
図９のように導通比最大値ｄｍａｘを設定した場合の電動機４の出力トルクＴと回転数Ｎの関係は図１０に示すようになる。従って、図９のように検知回転数の範囲ごとに導通比最大値ｄｍａｘを設定する場合は、設定した検知回転数範囲内の最小回転数における出力トルクの最大値が設定値を越えないように導通比最大値ｄｍａｘを設定する必要がある。しかるに、検知回転数Ｎｉｎに対応した導通比最大値ｄｍａｘの設定する数が比較的少ないのでメモリ−容量の小さい安価なマイクロコンピュ−タを用いて、電動機４の出力トルクを一定以下に抑えることができる。なお、導通比最大値ｄｍａｘが一定である検知回転数Ｎｉｎの範囲は８個にする必要はなく、導通比制限手段９を構成するマイクロコンピュ−タや、制御対象となる電動機４の特性に応じて設定すればよいものである。特に導通比最大値ｄｍａｘが一定である検知回転数Ｎｉｎの範囲を小さく区切れば、図５に示した導通比制限手段９の導通比最大値ｄｍａｘと検知回転数Ｎｉｎの関係と殆ど同じ特性になるので、図５の導通比制限手段９と殆ど同じ制御が可能になる。
【００５５】
以上のように図９に示す検知回転数Ｎｉｎを予め幾つかの範囲に分割し、各範囲ごとに導通比最大値ｄｍａｘを設定することで、安価な回路構成で三相巻線４ａやインバ−タ回路３に流れる電流を一定以下に抑え、電動機４の出力トルクを一定以下に抑えることができる。
【００５６】
（実施例３）
実施例３は本発明の請求項２に記載のインバ−タ装置の一実施例で、図１２を参照しながら説明する。なお、上記実施例１と同じ構成および作用効果のものには同一符号を付して詳細な説明を省略し、異なる部分を中心に説明する。
【００５７】
３１は２個の抵抗３１ａ，３１ｂの直列回路で構成された電圧検知手段で、抵抗３１ａの一端を整流回路２の高電位側の出力端子に接続し、抵抗３１ｂの一端は整流回路２の低電位側の出力端子に接続している。また、電圧検知手段３１は２個の抵抗３１ａ，３１ｂの接続点の電位を導通比制限手段３２に接続している。従って、整流回路２の出力電圧を抵抗３１ａと抵抗３１ｂの定数で分圧した電圧を導通比制限手段３２に出力している。導通比制限手段３２は電圧検知手段３１の出力値に応じて導通比最大値ｄｍａｘを補正している。本実施例では、整流回路２の出力電圧Ｖｉｎが２８２Ｖの時の電圧検知手段３１の出力を標準値とし、この標準値に対する電圧検知手段３１の出力電圧の割合に応じて導通比最大値ｄｍａｘを補正する。従って、補正された導通比最大値ｄｍａｘ２は次の（数１）で表すことができる。
【００５８】
【数１】

Figure 0004161436
【００５９】
ただし、導通比最大値ｄｍａｘの補正方法は上記の方法に限定されるものではない。例えば、この他の方法として電圧検知手段３１の出力値を複数のランクに分類し、各ランクごとにｄｍａｘの補正値Δｄｍａｘを導通比制限手段３２に予め設定しておき、導通比制限手段３２が電圧検知手段３１の出力値に応じて前記ランクを判定し、そのランクにおける補正値Δｄｍａｘを導通比最大値ｄｍａｘに加える方法を用いてもよい。
【００６０】
導通比制限手段３２は上記の方法により導通比最大値ｄｍａｘを補正した後、この補正された導通比最大値ｄｍａｘ２と導通比制御手段８が出力した導通比設定値ｄｓを比較して導通比の小さい方を制御手段５に出力し、制御手段５は位置検出手段６の出力論理に応じたパワ−スイッチング手段を導通比制限手段３２が出力した導通比でオンオフ制御する。
【００６１】
電動機４である直流ブラシレスモ−タにおいては、図４でも示したように三相巻線４ａへの印加電圧が大きくなるほど、同一回転数における出力トルクの最大値は大きくなる。すなわち、三相巻線４ａやインバ−タ回路３に流れる電流が大きくなっている。従って、交流電源１の変動等により整流回路２の出力電圧Ｖｉｎが変動すると、導通比最大値ｄｍａｘの補正がない場合は、その変動幅によってインバ−タ回路３、三相巻線４ａに流れる電流の最大値が変動し、電動機４の出力トルクの最大値が変動し、電動機４の出力軸にかかるトルクが過大になったり、もしくは電動機４の出力トルクの最大値が過小になり電動機４が起動しないといった異常が生じる可能性があった。しかるに電圧検知手段３１が整流回路２の出力電圧Ｖｉｎを検知し、導通比制限手段３２が電圧検知手段３１の出力に応じて導通比最大値ｄｍａｘを補正することにより、交流電源１の電圧が変動し整流回路２の出力電圧Ｖｉｎが変動しても、常にインバ−タ回路３や三相巻線４ａに流れる電流を所定値以下に抑え、電動機４の出力トルクを一定以下に抑えることできるので、インバ−タ回路３や三相巻線４ａが過電流により故障するのを防止し、さらに電動機４の出力軸に過大なトルクがかかるのを防止しながら、電動機４を起動することが可能になる。
【００６２】
また、電圧検知手段３１は整流回路２の出力電圧を検知しているので、電圧検知手段３１の出力に応じて導通比最大値を補正するだけでなく、例えばインバ−タ回路３の構成素子の耐圧を越えるような電圧が整流回路より出力された場合に、これを検知しインバ−タ装置の動作を止めたり、整流回路２を構成するコンデンサ２ｂ，２ｃの容量抜けが生じ電動機４の動作時に電圧リプルが大となるような場合においても電圧検知手段３１により整流回路２の出力電圧を検知することで異常検知を行うことができる。
【００６３】
（実施例４）
実施例４は図１２、図１３に示す本発明のインバ−タ装置の一実施例で、電動機４の起動時の制御、すなわち導通比制限手段９によりパワ−スイッチング手段３ａ〜３ｆの導通比を設定し、その後に導通比制御手段８により前記導通比を設定するようにしたもので、これ以外の上記実施例１と同じ構成および作用効果のものには同一符号を付して詳細な説明を省略し、異なる部分を中心に図１を利用して説明する。
【００６４】
上記構成において、インバ−タ装置における電動機４の回転数制御を図１２、図１３に示すステップ４１〜ステップ４３、ステップ５１〜ステップ５６（以下Ｓ４１、Ｓ４２、Ｓ４３、Ｓ５１・・という）のフロ−チャ−トに従い説明する。Ｓ４１で電動機４の運転を開始すると、Ｓ４２で電動機４の起動制御サブル−チンを開始する。この起動制御サブル−チン４２は図１３を参照しながら説明する。Ｓ５１で起動制御サブル−チンが開始されると、Ｓ５２で回転数検知手段７が電動機４の回転数を検知し、Ｓ５３でこの検知回転数Ｎｉｎが目標回転数Ｎｓより低いかどうかを判定し、検知回転数Ｎｉｎが目標回転数Ｎｓより低い場合は、Ｓ５４で導通比制限手段９が予め設定された検知回転数Ｎｉｎと導通比最大値ｄｍａｘの特性グラフに基づいて回転数検知手段７の出力した検知回転数Ｎｉｎに応じた導通比最大値ｄｍａｘを設定し、Ｓ５５でこの導通比最大値ｄｍａｘを制御手段５に出力する。その後、再び回転数検知手段７が電動機４の回転数を検知し、上記の動作を繰り返す。そして、その後に電動機４の回転数が増加し、Ｓ５３にて検知回転数Ｎｉｎが目標回転数Ｎｓ以上と判定されると、Ｓ５６で起動制御サブル−チンを終了し、図１２に示すフロ−チャ−トのＳ４３で回転数制御サブル−チンに入る。この回転数制御サブル−チンは上記実施例１で図７に従い説明した回転数制御サブル−チンと同じように行われる。
【００６５】
以上のように、電動機４の回転数が目標回転数Ｎｓに上昇するまで、導通比制限手段９によりパワ−スイッチング手段３ａ〜３ｆの導通比を設定することにより、電動機４の出力トルクを一定に抑えながら短時間で目標回転数Ｎｓまで電動機４の回転数を立ち上げることができる。
【００６６】
（実施例５）
実施例５は図１４、図１５に示す本発明のインバ−タ装置の一実施例で、電動機４の起動時の制御、すなわち導通比制限手段９により電動機４の起動時にパワ−スイッチング手段３ａ〜３ｆの導通比を所定値に設定し、その後徐々に導通比を増加させていくようにしたもので、これ以外の上記実施例１と同じ構成および作用効果のものには同一符号を付して詳細な説明を省略し、異なる部分を中心に図１を利用して説明をする。
【００６７】
上記構成において、インバ−タ装置における電動機４の起動制御を図１４、図１５に示すステップ６１〜ステップ６３、ステップ７１〜ステップ７８（以下Ｓ６１、Ｓ６２２、Ｓ６３、Ｓ７１・・という）のフロ−チャ−トに従い説明する。Ｓ６１で電動機４の運転を開始すると、Ｓ６２でソフトスタ−トサブル−チンを行う。このソフトスタ−トサブル−チンは図１５のフロ−チャ−トに示す通り、Ｓ７１でソフトスタ−トサブル−チンを開始すると、Ｓ７２で導通比制限手段９からの出力を禁止し、導通比設定値ｄｓをｄｓ１に設定し、制御手段５に出力する。制御手段５が導通比設定値ｄｓ１でパワ−スイッチング手段３ａ〜３ｆをオンオフ制御すると電動機４に交流電力が供給され、回転子４ｂが回転する。そして、所定時間経過後、Ｓ７３でホ−ルＩＣ６ａのパルス信号が所定回数入力されたかを判定し、そうでない場合はＳ７４で前回の導通比設定値ｄｓ１に導通比操作量Δｄｓを加算し、新たな導通比設定値ｄｓにする。Ｓ７５では導通比設定値ｄｓが所定値ｄｓｍａｘを越えているかを判定し、越えていない場合はＳ７６で導通比設定値ｄｓを制御手段５に出力し、越えている場合はＳ７７で導通比設定値をｄｓｍａｘにして制御手段５に出力する。その後再び所定時間ｔの経過後にＳ７３にてホ−ルＩＣ６ａのパルス信号が所定回数入力されたかを判定し、所定回数入力されたと判定した場合は、Ｓ７８でソフトスタ−トサブル−チンを終了し、図１４に示すフロ−チャ−トのＳ６３の回転数制御サブル−チンを行う。この回転数制御サブル−チンは上記実施例１で図７に示すフロ−チャ−トに従い説明した回転数制御サブル−チンと同じなので詳細な説明は省略する。
【００６８】
以上のように電動機４の起動時にソフトスタ−トサブル−チンを設けることにより、電動機４の起動時の導通比設定値を小さくすることができ、インバ−タ回路３や三相巻線４ａに過電流が流れるのを防止し、電動機４の出力トルクが過大になるのを防止することができる。また、本実施例のように電動機４の回転数検知をホ−ルＩＣ６ａのパルス信号を利用して行う場合には、電動機４の回転数が低い時の確定時間が長くなるという応答性の問題により、電動機４の立ち上げ速度が遅くなることがあるが、図１５に示したソフトスタ−トサブル−チンを行うことで、電動機４の回転数がある程度高くなるまでの間、回転数検知と回転数制御を行わず、導通比設定値を一方的に設定していくので、電動機４の立ち上げ速度を速くすることができる。なお、この時ソフトスタ−トサブル−チンにも導通比最大値ｄｓｍａｘを設定しているので、インバ−タ回路３や三相巻線４ａに流れる電流を一定値以下に抑えることができ、電動機４の出力軸に過大なトルクがかかるのを防止することができる。
【００６９】
（実施例６）
実施例６は図１６に示す本発明のインバ−タ装置の一実施例で、電動機４の起動時の制御、すなわち電動機４の起動時にパワ−スイッチング手段３ａ〜３ｆの導通比を所定値より増加させ、その後導通比制限手段９によりパワ−スイッチング手段３ａ〜３ｆの導通比を制御し、さらにその後導通比制御手段８でパワ−スイッチング手段３ａ〜３ｆの導通比を制御する構成にしたもので、これ以外の上記実施例１と同じ構成および作用効果のものには同一符号を付して詳細な説明を省略し、異なる部分を中心に図１を利用して説明をする。
【００７０】
上記構成において、インバ−タ装置における電動機４の起動制御を図１６に示すフロ−チャ−トのステップ８１〜ステップ８４（以下Ｓ８１〜Ｓ８４という）に従い説明する。Ｓ８１で電動機４の運転を開始すると、Ｓ８２でソフトスタ−トサブル−チンが行われる。このソフトスタ−トサブル−チンは上記実施例５で図１５に示すフロ−チャ−トに従い説明したフロ−と同じ構成なので詳細な説明は省略する。このソフトスタ−トサブル−チンが終了するとＳ８３で起動制御サブル−チンを行う。この起動制御サブル−チンは上記実施例４で図１３に示すフロ−チャ−トに従い説明したフロ−と同じであり、目標回転数Ｎｓまで電動機４の出力トルクを可能な限り大きくして回転させる。その後、電動機４の回転数が目標回転数Ｎｓまで達すると、Ｓ８４で導通比制御手段８と導通比制限手段９により上記実施例１で図７に示すフロ−チャ−トに従い説明したフロ−と同じ回転数制御サブル−チンを行う。
【００７１】
以上のように、電動機４の起動時にはまずソフトスタ−トサブル−チンを行い、次に起動制御サブル−チンを行い、最後に回転数制御サブル−チンを行うことにより、電動機４の低速時に回転数検知手段７による回転数検知を行う必要がなくなり、回転数検知手段７の検知速度が遅いことにより電動機４の起動が不安定になるということを回避することができる。また、回転数検知手段７が高速検知な回転数領域から導通比制限手段９により電動機４の出力トルクを可能な限り大きくして回転することができる。従って、電動機４の低速時における回転数検知の時間が長くても、電動機４を目標回転数まで短時間かつ安全に立ち上げることができる。
【００７２】
なお、上記各実施例で示したインバ−タ装置の構成や回転数制御方式や電動機の起動制御方式は一例であり、これに限定されるものではない。
【００７３】
【発明の効果】
以上のように本発明の請求項１に記載の発明によれば、交流電源と、前記交流電源を直流電源に変換する整流回路と、前記整流回路の出力する直流電源を交流電源に変換するインバ−タ回路と、前記インバ−タ回路の出力側に接続し、回転子に永久磁石を有する電動機と、前記インバ−タ回路を構成するパワ−スイッチング手段をオンオフ制御する制御手段と、前記電動機の回転子の回転数を検知する回転数検知手段と、前記回転数検知手段の出力を受けて前記パワ−スイッチング手段の導通比を制御する導通比制御手段と、前記導通比制御手段の出力する導通比の最大値を制御する導通比制限手段を備え、前記導通比制限手段は前記回転数検知手段の出力が小なら小に、大なら大に、導通比の最大値を設定し過電流を防止する構成したものであるから、電動機の三相巻線やインバ−タ回路に流れる電流を検知することなく、前記電流を一定以下に抑え、電動機の出力トルクを一定以下に抑えることができる。
【００７４】
また本発明の請求項２に記載の発明によれば、請求項１記載の発明において、整流回路の出力する直流電圧を検知する電圧検知手段を備え、導通比制限手段は前記電圧検知手段の出力を受けて、パワ−スイッチング手段の導通比の最大値を補正する構成にしたものであるから、交流電源の電圧変動等により整流回路の出力電圧が変動しても、電動機の三相巻線に流れる電流を検知することなく、前記電流を一定以下に抑え、電動機の出力トルクを一定以下に抑えることができる。
【００７５】
また本発明の請求項３に記載の発明によれば、請求項１または２記載の発明において、導通比制限手段は、回転数検知手段が検知した検知回転数の範囲に応じてパワ−スイッチング手段の導通比の最大値を設定する構成にしたものであるから、簡単な構成で電動機の出力トルクを一定以下に抑えることが可能になり、安価なインバ−タ装置を実現できる。
【００７６】
また本発明の請求項４に記載の発明によれば、請求項１〜３のいずれか１項に記載の発明において、電動機の起動時には導通比制限手段によりパワ−スイッチング手段の導通比を制御し、その後は導通比制御手段によりパワ−スイッチング手段の導通比を制御する構成にしたものであるから、電動機の三相巻線の電流に相当する電流を検知することなく、電動機の出力トルクを可能な限り大きくして回転することができる。従って、電動機の出力トルクが過大にならない状態で電動機を目標回転数まで短時間で立ち上げることができる。
【００７７】
また本発明の請求項５に記載の発明によれば、請求項１〜３のいずれか１項に記載の発明において、電動機の起動時にはパワ−スイッチング手段の導通比を所定値より増加させ、その後導通比制御手段によりパワ−スイッチング手段の導通比を制御する構成にしたものであるから、電動機の低速時に回転数検知手段による回転数検知の確定までの時間が長くなるような場合においても、パワ−スイッチング手段の導通比を一方的に設定していくので、電動機を目標回転数まで比較的高速に立ち上げることができる。また、電動機の起動時にはパワ−スイッチング手段の導通比を電動機の出力トルクが過大にならない範囲に設定することで、電動機の出力軸の破損を防止できる安全なインバ−タ装置を実現できる。
【００７８】
また本発明の請求項６に記載の発明によれば、請求項１〜３のいずれか１項に記載の発明において、電動機の起動時にはパワ−スイッチング手段の導通比を所定値より増加させ、その後は導通比制限手段によりパワ−スイッチング手段の導通比を制御し、さらにその後は導通比制御手段によりパワ−スイッチング手段の導通比を制御する構成にしたものであるから、電動機の低速時における回転数検知が必要なくなり、また回転数検知が可能な回転数領域から導通比制限手段により電動機の出力トルクを可能な限り大きくして電動機を回転することができるので、回転数検知手段が電動機の低速における回転数を検知する時間が長くても、電動機を目標回転数まで短時間かつ安全に立ち上げることができる。
【図面の簡単な説明】
【図１】 本発明インバ−タ装置の実施例１におけるブロック回路図
【図２】 同インバ−タ装置の動作時の各部の波形図
【図３】 本発明インバ−タ装置の各実施例における電動機の出力トルク−電流ピ−クの特性グラフ
【図４】 本発明インバ−タ装置の各実施例における電動機の出力トルク−回転数の特性グラフ
【図５】 本発明インバ−タ装置の実施例１における導通比制限手段の電動機回転数−導通比最大値の設定グラフ
【図６】 同インバ−タ装置の制御時における電動機の出力トルク−回転数の特性グラフ
【図７】 同インバ−タ装置における電動機の回転数制御サブル−チンのフロ−チャ−ト
【図８】 同インバ−タ装置を備えた電気洗濯機の縦断面図
【図９】 本発明インバ−タ装置の実施例２における導通比制限手段の電動機回転数−導通比最大値の設定グラフ
【図１０】 同インバ−タ装置の制御時における電動機の出力トルク−回転数の特性グラフ
【図１１】 本発明インバ−タ装置の実施例３におけるブロック回路図
【図１２】 本発明インバ−タ装置の実施例４における電動機の回転数制御のフロ−チャ−ト
【図１３】 同インバ−タ装置の制御時における電動機の起動制御サブル−チンのフロ−チャ−ト
【図１４】 本発明インバ−タ装置の実施例５における電動機の回転数制御のフロ−チャ−ト
【図１５】 同インバ−タ装置の制御時における電動機のソフトスタ−トサブル−チンのフロ−チャ−ト
【図１６】 本発明インバ−タ装置の実施例６における電動機の起動と回転数制御のフロ−チャ−ト
【符号の説明】
１ 交流電源
２ 整流回路
３ インバ−タ回路
４ 電動機
５ 制御手段
６ 位置検知手段
７ 回転数検知手段
８ 導通比制御手段
９、３２ 導通比制限手段[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inverter device provided in an electric device used in a general household.
[0002]
[Prior art]
In an inverter apparatus having a permanent magnet in a conventional rotor of an electric motor, a current detector and current control means are provided to keep the output torque of the electric motor constant, and the current detector is a three-phase winding of the electric motor. The current flowing in the line and the current flowing in the power switching means constituting the inverter device are detected, and the power control means receives the output of the current detector and has a predetermined current value. -Controlling the conduction ratio of the switching means.
[0003]
[Problems to be solved by the invention]
However, in the conventional inverter device, in order to keep the output torque of the motor below a certain level, it is necessary to provide a current detector and current control means to perform feedback control. The problem was that the configuration was complicated.
[0004]
Also, depending on the control method of the current control means and the operation amount of the conduction ratio of the power switching means, an overshoot with respect to a predetermined current value may occur at the start of the motor, and the three-phase winding and power switching There is a problem that causes an overcurrent to flow in the means or an excessive torque is applied to the output shaft of the motor.
[0005]
The present invention solves the problems of the above-described conventional inverter device, and sets the maximum value of the conduction ratio of the power switching means in accordance with the rotational speed of the electric motor, thereby enabling the current detector and the current control means. The purpose is to reliably suppress the current flowing in the power switching means and the three-phase winding of the motor to a certain level or less and to reduce the output torque of the motor to a certain level or less.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides an AC power source, a rectifier circuit that converts the AC power source into a DC power source, an inverter circuit that converts a DC power source output from the rectifier circuit into an AC power source, and the inverter. -An electric motor connected to the output side of the inverter circuit and having a permanent magnet in the rotor; a control means for controlling on / off of the power switching means constituting the inverter circuit; and detecting the rotational speed of the rotor of the electric motor A rotation speed detection means for controlling, a conduction ratio control means for receiving the output of the rotation speed detection means and controlling a conduction ratio of the power switching means, and a maximum value of the conduction ratio output by the conduction ratio control means. A conduction ratio limiting means, wherein the conduction ratio limiting means sets the maximum value of the conduction ratio to a small value when the output of the rotational speed detection means is small, and a large value when the output is large; Keep current below a certain level It is configured to prevent overcurrent.
[0007]
As a result, the current can be kept below a certain level and the output torque of the motor can be kept below a certain level without detecting the current flowing in the three-phase winding and the inverter circuit constituting the motor. A safe inverter device can be realized with the configuration.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The invention according to claim 1 of the present invention is an AC power source, a rectifier circuit that converts the AC power source into a DC power source, an inverter circuit that converts a DC power source output from the rectifier circuit into an AC power source, An electric motor connected to the output side of the inverter circuit and having a permanent magnet in the rotor, a control means for controlling on / off of the power switching means constituting the inverter circuit, and the rotational speed of the rotor of the electric motor. Rotational speed detection means for detecting, continuity ratio control means for receiving the output of the rotational speed detection means and controlling the continuity ratio of the power switching means, and controlling the maximum value of the continuity ratio output by the continuity ratio control means A conduction ratio limiting means that sets the maximum value of the conduction ratio to be small if the output of the rotation speed detection means is small, and large if large. Keep current below a certain level It is configured to prevent overcurrent.
[0009]
According to this configuration, the electric conduction ratio limiting means that sets the maximum value of the conduction ratio of the inverter circuit according to the output of the rotation speed detection means flows to the three-phase winding and the inverter circuit constituting the motor. Without detecting the current, the current can be kept below a certain level, and the output torque of the motor can be kept below a certain level.
[0010]
The invention according to claim 2 of the present invention is the invention according to claim 1, further comprising voltage detection means for detecting a DC voltage output from the rectifier circuit, and the conduction ratio limiting means receives the output of the voltage detection means. Thus, the maximum value of the conduction ratio of the power switching means is corrected.
[0011]
According to this configuration, the output voltage of the rectifier circuit varies due to voltage fluctuations of the AC power supply, etc., by the conduction ratio limiting means that receives the output of the voltage detection means and corrects the maximum value of the conduction ratio of the power switching means. However, without detecting the current flowing through the three-phase winding of the motor, the current can be suppressed below a certain level, and the output torque of the motor can be suppressed below a certain level.
[0012]
According to a third aspect of the present invention, in the first or second aspect of the present invention, the continuity ratio limiting means includes a continuity ratio of the power switching means according to the range of the detected rotational speed detected by the rotational speed detecting means. The maximum value is set.
[0013]
According to this configuration, the output torque of the electric motor can be kept constant with a simple configuration by the conduction ratio limiting means that sets the maximum value of the conduction ratio of the power switching means according to the range of the detected rotation speed detected by the rotation speed detection means. It becomes possible to suppress to the following, and an inexpensive inverter device can be realized.
[0014]
According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, when the motor is started, the conduction ratio of the power switching means is controlled by the conduction ratio limiting means. Thereafter, the conduction ratio of the power switching means is controlled by the conduction ratio control means.
[0015]
According to this configuration, the conduction ratio limiting means controls the conduction ratio of the power switching means when starting the motor, and the conduction ratio control means controls the conduction ratio of the power switching means after starting the motor. Without detecting the current corresponding to the current of the three-phase winding, the motor can be rotated with the output torque as large as possible. Therefore, the electric motor can be started up to the target rotational speed in a short time in a state where the output torque of the electric motor does not become excessive.
[0016]
According to a fifth aspect of the present invention, in the invention according to any one of the first to third aspects, when the motor is started, the conduction ratio of the power switching means is increased from a predetermined value, and then the conduction ratio is increased. The continuity ratio of the power switching means is controlled by the control means.
[0017]
According to this configuration, the conduction ratio of the power switching means is increased from a predetermined value when the motor is started, and the conduction ratio of the power switching means is controlled by the conduction ratio control means after the motor is started. Even in the case where the time until the detection of the rotational speed by the rotational speed detection means becomes long, the conduction ratio of the power switching means is set unilaterally, so that the electric motor stands up to the target rotational speed at a relatively high speed. Can be raised. Further, by setting the conduction ratio of the power switching means within a range where the output torque of the motor does not become excessive when the motor is started, a safe inverter device that can prevent the output shaft of the motor from being damaged can be realized.
[0018]
The invention according to claim 6 of the present invention is the invention according to any one of claims 1 to 3.
When the motor is started, the conduction ratio of the power switching means is increased from a predetermined value. Thereafter, the conduction ratio of the power switching means is controlled by the conduction ratio limiting means, and thereafter, the power switching means is controlled by the conduction ratio control means. The continuity ratio is controlled.
[0019]
According to this configuration, it is not necessary to detect the rotational speed of the electric motor at a low speed, and the electric motor can be rotated with the output torque of the electric motor as large as possible from the rotational speed region where the rotational speed can be detected by the conduction ratio limiting means. . Therefore, even if the time for which the rotational speed detection means detects the rotational speed at a low speed of the electric motor is long, the electric motor can be started up to the target rotational speed in a short time and safely.
[0020]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
[0021]
(Example 1)
The first embodiment of the present invention is an inverter apparatus according to the first aspect of the present invention, and FIG. 1 shows a block circuit configuration thereof. In this inverter device, a rectifier circuit 2 is connected to an AC power source 1, an inverter circuit 3 is connected to a high potential side output terminal of the rectifier circuit 2, and further, an output terminal of the inverter circuit 3 is connected to an output terminal of the inverter circuit 3. An electric motor 4 is connected.
[0022]
In the rectifier circuit 2, a voltage doubler rectifier circuit is constituted by a series circuit of a diode rich 2a and two capacitors 2b and 2c. However, the present invention is not particularly limited to this, and is composed of a diode rich and one capacitor. A full-wave rectifier circuit may be configured.
[0023]
The inverter circuit 3 has a three-phase hexagonal structure by six power switching means 3a to 3f. The power switching means 3a to 3f are composed of a parallel circuit of a diode reversely connected to an IGBT that can cope with high frequency switching and a large current capacity. May be used. Further, the configuration of the inverter circuit 3 is not limited to three-phase six stones, but may be three-phase three stones.
[0024]
The electric motor 4 employs a DC brushless motor having an armature winding in which a three-phase winding 4a is formed on a stator and a permanent magnet on a rotor. And although the electric motor 4 makes the number of poles of the rotor 4b 4 poles, it is not limited to this.
[0025]
The control means 5 comprises a PWM circuit 5a, a three-phase distribution circuit 5b, a drive circuit 5c and the like, and these circuits are constituted by a microcomputer, a logic circuit, or the like. The PWM circuit 5a is constituted by a counter and a magnitude comparator in the microcomputer, and outputs high and low signals alternately at about 15.7 kHz to the drive circuit 5c. Then, the PWM circuit 5a compares the output value of the conduction ratio limiting means 9 described later with the output value of the counter by the magnitude comparator, and drives the high signal for a period corresponding to the output value of the conduction ratio limiting means 9. Output to the circuit 5c. The three-phase distribution circuit 5b sets an on / off combination of the power switching means 3a to 3f according to the output of the position detection means 6 for detecting the position of the rotor 4b of the electric motor 4, which will be described later, and outputs the combination to the drive circuit 5c. The drive circuit 5c receives the outputs of the PWM circuit 5a and the three-phase distribution circuit 5b, controls on / off of a desired power switching means with a set conduction ratio, supplies AC power to the motor 4, and causes the motor 4 to rotate. ing.
[0026]
The position detecting means 6 is composed of three hole ICs 6a to 6c arranged at an electrical angle of 120 degrees. When the facing surface of the permanent magnet of the rotor 4b is the S pole, the position is high. In some cases, each low signal is output to the control means 5. As will be described in detail later, the control means 5 performs on / off control of the power switching means 3a to 3f in response to the combination of the outputs of the hall ICs 6a to 6c. In this embodiment, the arrangement of the hall ICs 6a to 6c is an example. For example, one of the hall ICs 6a to 6c is moved by 180 degrees in electrical angle, and the logic of the hall IC is changed to the rotor. When the opposing surface of the 4b permanent magnet is the south pole, a low signal may be output to the control means 5, and when it is the north pole, a high signal may be output to the control means 5. Further, the position detection means 6 is not limited to the configuration using the Hall IC, but detects an induced voltage generated in each phase winding of the three-phase winding 4a of the electric motor 4, and based on this detection signal. Then, the position of the permanent magnet of the rotor 4b may be detected, or the position may be detected optically with a photo interrupter or the like.
[0027]
Reference numeral 7 denotes a rotation speed detection means connected to the output side of the position detection means 6, 8 denotes a conduction ratio control means connected to the output side of the rotation speed detection means 7, and 9 denotes a rotation speed detection means 7 and a conduction ratio control means 8. These are continuity ratio limiting means connected to the output side, and these are constituted by a microcomputer.
[0028]
The rotation speed detection means 7 detects a period during which the hall IC 6a outputs a high signal by a counter in the microcomputer, and determines the rotation speed Nin of the rotor 4b based on the period. This rotational speed detection method is merely an example, and the output of the hall IC 6a can be detected as a voltage value through an integration circuit, or separately, for a predetermined period of time to obtain control stability. The high signal output time of the hall IC may be detected using a counter.
[0029]
The conduction ratio control means 8 inputs the detected rotation speed Nin of the rotor 4b detected by the rotation speed detection means 7 and the target rotation speed Ns, and sets the conduction ratio of the power switching means 3a to 3f according to these two input values. The value ds is output to the conduction ratio limiting means 9. In this embodiment, the proportional component (P component) improves the stability and responsiveness of the rotational speed control, and uses the integral component (I component) to make the steady-state deviation with respect to the target rotational speed Ns zero (PI). ) Control is being performed. However, this control method is not limited to proportional-integral control, and in addition to proportional component and integral component, PID control or proportional control in which a differential component (D component) is incorporated as a component in order to increase the response speed. Fuzzy control may be used. Further, depending on the performance of the microcomputer, the conduction ratio control means 8 may be composed of an operational amplifier or the like.
[0030]
Although the conduction ratio limiting means 9 will be described in detail later, the detected rotation speed Nin of the rotor 4b detected by the rotation speed detection means 7 is inputted, and the maximum value dmax of the conduction ratio corresponding to the detected rotation speed Nin is set. On the other hand, when the conduction ratio set value ds is input from the conduction ratio control means 8 to the conduction ratio restriction means 9, the conduction ratio maximum value dmax previously set in the conduction ratio restriction means 9 is compared with the conduction ratio set value ds. Then, the smaller conduction ratio is output to the control means 5. Then, the control means 5 sets on / off of the power switching means 3 a to 3 f by the position detection means 6, and performs on / off control of the power switching means set to on with the conduction ratio output by the conduction ratio limiting means 9. In this embodiment, the relationship between the conduction ratio maximum value dmax and the detected rotational speed Nin in the graph shown in FIG. 5 is set in advance in the microcomputer.
[0031]
As described above, every time the number of rotations of the rotor 4b is detected, the conduction ratio limiting means 9 sets the maximum value of the conduction ratio of the power switching means so that the application to the three-phase winding 4a of the electric motor 4 is achieved. Since the voltage can be reduced to a predetermined value or less, the current flowing through the three-phase winding 4a can be suppressed to a predetermined value or less at a detected rotational speed Nin or higher, and the output torque of the electric motor 4 can be suppressed to a predetermined value or less. . However, the circuit configuration and the configuration of the electric motor in this embodiment are merely examples, and other configurations may be used.
[0032]
FIG. 2 shows waveforms (a) to (l) of signals at various parts in the inverter apparatus of FIG. Waveforms (a) to (c) are output waveforms of the hall ICs 6 a to 6 c of the position detection means 6. Among these signals, the rotation speed detecting means 7 detects the output signal of the hall IC 6a, and by detecting the period of the high signal of the hall IC 6a, the rotation speed of the electric motor 4 corresponding to the period is detected. It outputs to the conduction ratio control means 8 and the conduction ratio restriction means 9. Further, the three-phase distribution circuit 5b outputs a combination of on / off of the power switching means 3a to 3f as shown in the waveforms (d) to (i) of FIG. 2 according to the logic of the output signal of the position detection means 6. The waveform (d) is the on / off state of the power switching means 3a, the waveform (e) is the on / off state of the power switching means 3b, the waveform (f) is the on / off state of the power switching means 3c, and the waveform (g) is the power switching. The on / off state of the means 3d, the waveform (h) shows the on / off state of the power switching means 3e, and the waveform (i) shows the on / off state of the power switching means 3f. The power switching means 3a to 3f all perform on / off control of the power switching means in synchronization with the output signal of the PWM circuit 5a in synchronism with the phase switching timing of the three phases U, V and W. ing. Thereby, the noise generated at the time of phase switching of the three-phase winding 4a by the power switching means 3a to 3f can be reduced. The ratio of the ON period to the OFF period output from the PWM circuit 5a at this time, that is, the ratio of the ON period to the OFF period of the power switching means is the conduction ratio set by the conduction ratio control means 8 and the conduction ratio limiting means 9. It is a value according to. When any two power switching means are turned on by the control means 5, a voltage is applied to the two input terminals of the electric motor 4, and the applied voltage and the induced voltage due to the rotation of the rotor 4 b of the electric motor 4 are applied. Due to the difference voltage, phase currents (j) to (l) flow. The phase currents (j) to (l) make the current flowing in the positive direction when the power switching means 3a to 3c are turned on.
[0033]
FIG. 3 is a graph showing the relationship between the peak value of the current flowing through the three-phase winding 4a of the motor 4 constituted by the DC brushless motor of this embodiment and the output torque. As shown in FIG. 3, in the DC brushless motor, the output torque is obtained by multiplying the current flowing through the three-phase winding 4a by the torque constant Kt.
[0034]
As described above, in the DC brushless motor, the peak value of the current flowing through the three-phase winding 4a and the output torque are almost proportional.
[0035]
FIG. 4 is a graph showing the relationship between the rotational speed and output torque for each conduction ratio of the power switching means 3a to 3f in the DC brushless motor of this embodiment. At this time, the input voltage of the AC power source 1 is AC 100V, and the DC voltage output from the rectifier circuit 2 is set to about 282V. Graph (a) shows the characteristics when the conduction ratio of the power switching means 3a to 3f is 100%. Graph (A) shows the characteristics when the conduction ratio of the power switching means 3a to 3f is 75%. Graph (c) shows the characteristics when the conduction ratio of the power switching means 3a to 3f is 50%. Graph (d) shows the characteristics when the conduction ratio of the power switching means 3a to 3f is 25%. As can be seen from FIG. 4, the rotational speed at which the output torque Ts is obtained differs depending on the conduction ratio. In the case of FIG. 4, when the conduction ratio is 100%, the output torque becomes Ts at the rotation speed N1, when the conduction ratio is 75%, the output torque becomes Ts at the rotation speed N2, and when the conduction ratio is 50%, the rotation speed N3. The output torque is Ts, and the output torque is Ts at the rotational speed N4 at the conduction ratio of 25%. Therefore, the output torque of the electric motor 4 can be suppressed to a certain level or less by setting the conduction ratio maximum value dmax of the power switching means 3a to 3f according to the rotational speed of the rotor 4b.
[0036]
In general, in a DC brushless motor, an induced voltage is obtained by multiplying the rotational speed of the rotor 4b having a permanent magnet by an induced voltage constant, and the difference between this induced voltage and the voltage applied to the three-phase winding 4a. A current is supplied to the three-phase winding 4a by this voltage, and torque is generated by this current. The applied voltage of the three-phase winding 4a can be controlled by controlling the conduction ratio of the power switching means 3a to 3f. In this embodiment, the applied voltage is obtained by multiplying the DC voltage output from the rectifier circuit 2 by the conduction ratio of the power switching means 3a to 3f.
[0037]
Therefore, the maximum value of the voltage applied to the three-phase winding 4a can be limited by limiting the maximum value of the conduction ratio of the power switching means 3a to 3f by the conduction ratio limiting means 9, so that the graph (A) of FIG. The relationship between the rotational speed and the output torque can be controlled as in (i) to (d). As described above, in the DC brushless motor, a current flows through the three-phase winding 4a in accordance with the voltage difference between the voltage applied to the three-phase winding 4a and the induced voltage generated by the rotation of the rotor 4b. This is because a value obtained by multiplying this current by the torque constant Kt has a characteristic of becoming an output torque.
[0038]
FIG. 5 is an example of a graph showing the relationship between the detected rotation speed Nin of the rotor 4b provided in advance in the conduction ratio limiting means 9 of the inverter device of this embodiment and the conduction ratio maximum value dmax of the power switching means 3a to 3f. It is. In this embodiment, the conduction ratio limiting means 9 is configured so that the conduction ratio maximum value dmax and the detected rotation speed Nin are a continuous function, and the conduction ratio maximum value dmax is calculated every time the detection rotation speed Nin is input. is doing. However, it is not necessary to provide a function to calculate the conduction ratio maximum value dmax for each input of the detected rotation speed Nin, and the conduction ratio maximum value dmax is stored in the memory in the microcomputer according to the detected rotation speed Nin. In addition, the conduction ratio maximum value dmax corresponding to the input detected rotational speed Nin may be set for each input of the detected rotational speed Nin.
[0039]
FIG. 6 is a graph showing the relationship between the rotational speed N of the motor 4 and the output torque T when the conduction ratio maximum value dmax of the power switching means 3a to 3f is set as shown in FIG. In FIG. 5, the maximum conduction voltage dmax of the power switching means 3a to 3f is provided according to the rotational speed of the rotor 4b, whereby the maximum applied voltage to the three-phase winding 4a according to the rotational speed is determined. As a result, the maximum output torque corresponding to the rotational speed of the electric motor 4 is also limited, and the characteristics shown in FIG. 6 are obtained.
[0040]
As described above, by providing the conduction ratio maximum value dmax of the power switching means 3a to 3f according to the rotational speed of the motor 4, the applied voltage of the three-phase winding 4a of the motor 4 is limited, and the three-phase winding The current flowing through the wire 4a is also limited, and as a result, the output torque of the electric motor 4 is limited. Therefore, it is possible to prevent an overcurrent from flowing through the three-phase winding 4a and the power switching means 3a to 3f without detecting the current of the three-phase winding 4a and the power switching means 3a to 3f. It is possible to prevent excessive torque from being applied to the output shaft. Further, in the present embodiment, when the rotation speed of the electric motor 4 is increased by setting the conduction ratio maximum value dmax after detecting the rotation speed of the rotor 4b, the three-phase is set. Since the induced voltage generated in the winding 4a increases and the current flowing through the three-phase winding 4a decreases, the maximum output torque of the motor 4 is not exceeded, and the three-phase winding 4a and inverter of the motor 4 are not exceeded. A safe inverter device in which no overcurrent flows in the components of the circuit 3 can be realized.
[0041]
In the above embodiment, the rotational speed control of the electric motor 4 in the inverter apparatus will be described in accordance with the flowchart of steps 11 to 17 (hereinafter referred to as S11, S12, S13...) Shown in FIG. When the rotational speed control routine of the motor 4 is started in S11, the rotational speed of the motor 4 is detected by the rotational speed detection means 7 in S12, and the detected rotational speed Nin is output to the conduction ratio control means 8 and the conduction ratio limiting means 9. To do. In S13, the continuity ratio control means 8 performs proportional-integral control based on the detected rotational speed Nin and a preset target rotational speed Ns, and outputs the continuity ratio set value ds to the continuity ratio limiting means 9. In S14, the conduction ratio limiting means 9 sets a conduction ratio maximum value dmax according to the detected rotation speed Nin based on the preset graph shown in FIG. 5, and in S15, the conduction ratio restriction means 9 conducts with the conduction ratio set value ds. The ratio maximum value dmax is compared, and if the conduction ratio set value ds is larger than the conduction ratio maximum value dmax, the conduction ratio maximum value dmax is output to the control means 5 as the conduction ratio in S16. If the conduction ratio set value ds is smaller than the conduction ratio maximum value dmax in S15, the conduction ratio set value ds is output to the control means 5 as a conduction ratio in S17. And the control means 5 carries out on-off control of the power switching means 3a-3f by said each conduction | electrical_connection ratio. Thereafter, the rotational speed of the electric motor 4 is detected again by the rotational speed detection means 7 in S12, and the above controlled control is repeated.
[0042]
As described above, by providing the conduction ratio limiting means 9, the maximum value of the current can be controlled without detecting the current of the three-phase winding 4a of the electric motor 4 or the current flowing through the inverter circuit 3. Can do. Therefore, the output torque of the electric motor 4 can also be kept constant.
[0043]
FIG. 8 shows a structural diagram of an electric washing machine provided with an inverter device in this embodiment. A water receiving tank 21 is provided with a washing / dehydrating tank 23 having an agitating blade 22 rotatably at an inside fixed portion, and is rotatably suspended inside the washing machine body 25 by a support bar 24. A speed reduction mechanism 26 is provided at the outer bottom of the water receiving tank 21 and transmits the power of the electric motor 4 provided at the lower part to the stirring blade 22 and the washing / dehydrating tank 23. The speed reduction mechanism 26 has a planetary gear, and when the stirring blade 22 is rotationally driven, the sun gear is driven by the output shaft of the electric motor 4 so that the rotation of the planetary gear is transmitted to the stirring blade 22. Thus, the speed is reduced to 1/6 and the output torque of the electric motor 4 is converted to 6 times. In the control of rotationally driving the washing / dehydrating tub 23 such as dehydration, the speed reduction mechanism 26 is separated from the output shaft of the electric motor 4 by a clutch (not shown), and the washing / dehydrating tub 23 is connected to the output shaft of the electric motor 4. Directly rotationally driven. 27 is a water supply valve for supplying water to the washing / dehydrating tub 23, and 28 is a drain valve for draining the washing water in the washing / dehydrating tub 23.
[0044]
The operation of the electric washing machine will be described. When the operation is started with the user putting laundry and detergent into the washing and dewatering tank 23, the water supply valve 27 is opened, tap water is put into the water receiving tank 21, the water level is raised to a predetermined level, and the stirring blade 22 is turned on. Rotate to clean. In this cleaning, the washing and dewatering tub 23 and the output shaft of the electric motor 4 are separated by a clutch, the speed reduction mechanism 26 and the output shaft of the electric motor 4 are connected, and the rotational speed of the electric motor 4 is reduced to 1/6 to reduce the stirring blade. 22 is rotated. At this time, the control means 5 in FIG. 1 controls the electric motor 4 so that the electric motor 4 repeats normal rotation and reverse rotation. When the washing with the stirring blade 22 is completed, the drain valve 28 is opened, and the washing water in the water receiving tank 21 is drained. Thereafter, the output shaft of the electric motor 4 and the washing / dehydrating tub 23 are directly connected, and the washing / dehydrating tub 23 is directly rotated by the electric motor 4 to dehydrate the cleaning liquid contained in the laundry.
[0045]
Subsequently, the laundry rinsing process is performed. In the same manner as the above-described operation during washing, the agitating blade 22 is rotated by the electric motor 4 through the speed reduction mechanism together with the supply of the rinse water.
[0046]
Further, in the dehydration process, the drain valve 28 is opened to drain the rinse water in the water receiving tub 21, the washing / dehydration tub 23 and the electric motor 4 are directly connected by a clutch, and the washing / dehydration tub 23 is rotated at 900 rpm by the electric motor 4. Thus, the laundry is dehydrated by centrifugal force.
[0047]
As described above, the electric washing machine shown in FIG. 8 rotates the electric motor 4 to wash and dehydrate the laundry. The rotation control of the electric motor 4 is controlled by the inverter circuit 3, the control means 5, the conduction ratio control means 8, This is performed by the inverter device of the present invention comprising the conduction ratio limiting means 9. Here, as described in the explanation of FIG. 1, the conduction ratio control means 8 inputs the target rotation speed Ns and the detected rotation speed Nin detected by the rotation speed detection means 7, and the power switching means 3a to 3f by proportional integral control. And the rotational speed is increased to the target rotational speed Ns and stabilized at the target rotational speed Ns. However, for example, the laundry is entangled by rotating the stirring blade 22 at the time of washing by the stirring blade 22, and the load on the stirring blade 22 is suddenly increased. , The conduction ratio control means 8 increases the number of revolutions, so that an increase in the conduction ratio causes an overcurrent to flow through the three-phase winding 4a and the inverter circuit 3 and to the output shaft of the motor 4. Such torque becomes excessive or exceeds the rated current of the power switching means 3a to 3f.
[0048]
Therefore, in the present invention, as described in the explanation of FIG. 1, the conduction ratio limiting means 9 sets the conduction ratio maximum value dmax corresponding to the detected rotation speed Nin detected by the rotation speed detection means 7, thereby enabling the three-phase winding. The rotational speed of the motor 4 can be increased while the current flowing through the inverter 4a and the inverter circuit 3 is kept constant. Therefore, it is possible to increase the rotation speed of the electric motor 4 while suppressing the output torque of the electric motor 4 below a certain level.
[0049]
As described above, by providing the conduction ratio limiting means 9, the current flowing through the three-phase winding 4 a and the inverter circuit 3 can be kept constant without particularly providing the current detection means and the current control means, and the electric motor Thus, it is possible to control the rotation speed of the electric motor 4 while keeping the output torque 4 constant. Therefore, it is possible to prevent the three-phase winding 4a and the inverter circuit 3 from being damaged due to an overcurrent, or an excessive torque being applied to the output shaft of the electric motor 4 to break the output shaft. In this embodiment, an example in which the stirring blade 22 is rotationally driven by the electric motor 4 via the speed reduction mechanism 26 is shown, but the conduction ratio limit is similarly applied when the washing and dewatering tub 23 is directly driven by the electric motor 4. The rotation of the electric motor 4 can be controlled while the output torque is kept below a certain level by the means 9. In particular, in an electric washing machine of a type in which the washing and dewatering tub 23 is directly driven to rotate by the electric motor 4 with water in the water receiving tub 21 and the water is passed through the laundry by centrifugal force for washing. Although torque is required, the continuity ratio limiting means 9 controls the continuity ratio maximum value dmax according to the detected rotational speed Nin as in this embodiment, so that the motor 4 is started while the output torque of the motor 4 is kept below a certain level. It is possible to prevent an overcurrent from flowing through the three-phase winding 4a and the inverter circuit 3 and an excessive torque applied to the output shaft of the motor 4.
[0050]
Although not particularly shown in the present embodiment, during the period when the low-potential-side power switching means 3a to 3f are in the on state, for example, a diode or charging resistance is supplied from a direct current power source constituted by a switching power source or the like. In the inverter device that charges the capacitor via the power supply and uses it as a drive power source for the power switching means 3a to 3c on the high potential side, power switching is performed by the conduction ratio limiting means 9 when the motor 4 is at a low speed. By limiting the maximum conduction ratio value dmax of the means 3a to 3f, the power switching means 3a to 3c are surely provided with an off period, and the charging period of the driving power source of the high potential side power switching means 3a to 3c is As a result, the bootstrap capacitor constituting the drive power supply is discharged, the potential is lowered, and the power switching means 3a to 3c are turned off. Will be no way, the motor 4 can be prevented abnormal that does not start.
[0051]
Further, in a device such as the electric washing machine shown in FIG. 8 that transmits the output torque of the electric motor 4 to the load via the speed reduction mechanism 26, not only the output shaft of the motor 4 but also the components of the speed reduction mechanism 26. However, if the output torque of the electric motor 4 becomes excessive, there is a possibility that the motor 4 is damaged. In this case, the conduction ratio limiting means 9 is provided with a graph set differently from the setting graph of the rotational speed-conduction ratio maximum value shown in FIG. 4 can be driven to rotate. Therefore, by providing a plurality of setting tables for the rotation speed-conduction ratio maximum value of the motor, even in a device having a plurality of protection targets, the motor 4 can be rotationally driven so that the output torque of the motor 4 does not become excessive. it can.
[0052]
(Example 2)
In the second embodiment, the conduction ratio limiting means in the inverter device of the present invention is different from the conduction ratio limiting means 9 shown in FIG. Therefore, detailed description is omitted, and different parts are mainly described with reference to FIG. That is, the conduction ratio limiting means 9 in the second embodiment has the relationship shown in FIG. 9 between the detected rotation speed Nin output from the rotation speed detection means 7 and the conduction ratio maximum value dmax of the power switching means 3a to 3f. Thus, the table is set in advance.
[0053]
The above embodiment will be described with reference to FIG. The detected rotation speed Nin is divided into eight ranges Na to Nh in advance, and the conduction ratio maximum value dmax is set for each range. The conduction ratio limiting means 9 receives the detected rotational speed Nin every time the rotational speed detecting means 7 detects the rotational speed of the rotor 4b, and determines which range of the detected rotational speeds Na to Nh is entered. Then, the conduction ratio maximum value dmax is set. Thereafter, the conduction ratio set value ds output from the conduction ratio control means 8 is compared with the conduction ratio maximum value dmax, and the smaller conduction ratio is input to the control means 5.
[0054]
The relationship between the output torque T of the motor 4 and the rotational speed N when the conduction ratio maximum value dmax is set as shown in FIG. 9 is as shown in FIG. Accordingly, when the conduction ratio maximum value dmax is set for each range of the detected rotational speed as shown in FIG. 9, the maximum value of the output torque at the minimum rotational speed within the set detected rotational speed range does not exceed the set value. It is necessary to set the continuity ratio maximum value dmax. However, since the set number of the conduction ratio maximum value dmax corresponding to the detected rotational speed Nin is relatively small, the output torque of the motor 4 can be suppressed to a certain level or less by using an inexpensive microcomputer having a small memory capacity. it can. The range of the detected rotational speed Nin where the continuity ratio maximum value dmax is constant does not need to be eight, depending on the characteristics of the microcomputer constituting the continuity ratio limiting means 9 and the electric motor 4 to be controlled. This is what you need to set. In particular, if the range of the detected rotation speed Nin where the continuity ratio maximum value dmax is constant is divided into small parts, the relationship between the continuity ratio maximum value dmax of the continuity ratio limiting means 9 and the detected rotation speed Nin shown in FIG. Therefore, almost the same control as the conduction ratio limiting means 9 of FIG. 5 is possible.
[0055]
As described above, the detected rotation speed Nin shown in FIG. 9 is divided into several ranges in advance, and the conduction ratio maximum value dmax is set for each range, so that the three-phase winding 4a and the inverter can be formed with an inexpensive circuit configuration. It is possible to suppress the current flowing through the inverter circuit 3 below a certain level, and to suppress the output torque of the electric motor 4 below a certain level.
[0056]
(Example 3)
A third embodiment is an embodiment of an inverter device according to claim 2 of the present invention and will be described with reference to FIG. The same components and effects as those of the first embodiment are denoted by the same reference numerals, detailed description thereof is omitted, and different portions will be mainly described.
[0057]
Reference numeral 31 denotes a voltage detection means constituted by a series circuit of two resistors 31a and 31b. One end of the resistor 31a is connected to the output terminal on the high potential side of the rectifier circuit 2, and one end of the resistor 31b is a low voltage of the rectifier circuit 2. It is connected to the output terminal on the potential side. The voltage detection means 31 connects the potential at the connection point of the two resistors 31 a and 31 b to the conduction ratio limiting means 32. Therefore, a voltage obtained by dividing the output voltage of the rectifier circuit 2 by the constants of the resistors 31 a and 31 b is output to the conduction ratio limiting means 32. The conduction ratio limiting means 32 corrects the conduction ratio maximum value dmax according to the output value of the voltage detection means 31. In this embodiment, the output of the voltage detection means 31 when the output voltage Vin of the rectifier circuit 2 is 282 V is set as a standard value, and the conduction ratio maximum value dmax is set in accordance with the ratio of the output voltage of the voltage detection means 31 to the standard value. to correct. Therefore, the corrected conduction ratio maximum value dmax2 can be expressed by the following (Equation 1).
[0058]
[Expression 1]
Figure 0004161436
[0059]
However, the correction method of the conduction ratio maximum value dmax is not limited to the above method. For example, as another method, the output value of the voltage detection means 31 is classified into a plurality of ranks, and a correction value Δdmax of dmax is preset in the conduction ratio restriction means 32 for each rank, and the conduction ratio restriction means 32 A method may be used in which the rank is determined in accordance with the output value of the voltage detection means 31, and the correction value Δdmax at the rank is added to the conduction ratio maximum value dmax.
[0060]
After the conduction ratio limit means 32 corrects the conduction ratio maximum value dmax by the above method, the corrected conduction ratio maximum value dmax2 is compared with the conduction ratio set value ds output by the conduction ratio control means 8 to determine the conduction ratio. The smaller one is output to the control means 5, and the control means 5 performs on / off control of the power switching means corresponding to the output logic of the position detection means 6 with the conduction ratio output by the conduction ratio limiting means 32.
[0061]
In the DC brushless motor that is the electric motor 4, as shown in FIG. 4, the maximum value of the output torque at the same rotational speed increases as the applied voltage to the three-phase winding 4a increases. That is, the current flowing through the three-phase winding 4a and the inverter circuit 3 is large. Therefore, when the output voltage Vin of the rectifier circuit 2 fluctuates due to fluctuations in the AC power supply 1 and the like, if there is no correction of the maximum conduction ratio dmax, the current flowing through the inverter circuit 3 and the three-phase winding 4a depending on the fluctuation width The maximum value of the output torque of the electric motor 4 fluctuates, the torque applied to the output shaft of the electric motor 4 becomes excessive, or the maximum value of the output torque of the electric motor 4 becomes excessively small and the electric motor 4 starts. There was a possibility that an abnormality would occur. However, the voltage detection means 31 detects the output voltage Vin of the rectifier circuit 2, and the conduction ratio limiting means 32 corrects the conduction ratio maximum value dmax according to the output of the voltage detection means 31, whereby the voltage of the AC power supply 1 fluctuates. Even if the output voltage Vin of the rectifier circuit 2 fluctuates, the current flowing through the inverter circuit 3 and the three-phase winding 4a can be kept below a predetermined value and the output torque of the motor 4 can be kept below a certain level. It is possible to start up the motor 4 while preventing the inverter circuit 3 and the three-phase winding 4a from failing due to an overcurrent and further preventing an excessive torque from being applied to the output shaft of the motor 4. .
[0062]
Further, since the voltage detection means 31 detects the output voltage of the rectifier circuit 2, not only the maximum conduction ratio value is corrected in accordance with the output of the voltage detection means 31, but also, for example, of the constituent elements of the inverter circuit 3 When a voltage exceeding the withstand voltage is output from the rectifier circuit, this is detected and the operation of the inverter device is stopped, or the capacity of the capacitors 2b and 2c constituting the rectifier circuit 2 is lost and the motor 4 is in operation. Even when the voltage ripple becomes large, the abnormality can be detected by detecting the output voltage of the rectifier circuit 2 by the voltage detection means 31.
[0063]
Example 4
The fourth embodiment is an embodiment of the inverter device of the present invention shown in FIGS. 12 and 13, and controls the start-up of the motor 4, that is, the conduction ratio of the power switching means 3a to 3f by the conduction ratio limiting means 9. The continuity ratio is set by the continuity ratio control means 8 after that, and the same configurations and operational effects as those of the first embodiment other than the above are denoted by the same reference numerals and will be described in detail. The description will be omitted with reference to FIG.
[0064]
In the above configuration, the rotational speed control of the electric motor 4 in the inverter device is performed in the flow of steps 41 to 43 and steps 51 to 56 (hereinafter referred to as S41, S42, S43, S51...) Shown in FIGS. This will be explained according to the chart. When the operation of the electric motor 4 is started in S41, the activation control subroutine for the electric motor 4 is started in S42. The activation control subroutine 42 will be described with reference to FIG. When the activation control subroutine is started in S51, the rotational speed detection means 7 detects the rotational speed of the electric motor 4 in S52, and in S53, it is determined whether or not the detected rotational speed Nin is lower than the target rotational speed Ns. When the detected rotation speed Nin is lower than the target rotation speed Ns, the conduction ratio limiting means 9 outputs the rotation speed detection means 7 based on the characteristic graph of the detected rotation speed Nin and the conduction ratio maximum value dmax set in advance in S54. A continuity ratio maximum value dmax corresponding to the detected rotational speed Nin is set, and this continuity ratio maximum value dmax is output to the control means 5 in S55. Thereafter, the rotational speed detection means 7 detects the rotational speed of the electric motor 4 again and repeats the above operation. After that, when the rotational speed of the electric motor 4 increases and it is determined in S53 that the detected rotational speed Nin is equal to or higher than the target rotational speed Ns, the start control subroutine is terminated in S56, and the flowchart shown in FIG. -Enter the rotation speed control subroutine at S43. The rotation speed control subroutine is performed in the same manner as the rotation speed control subroutine described in the first embodiment with reference to FIG.
[0065]
As described above, the output torque of the motor 4 is kept constant by setting the conduction ratio of the power switching means 3a to 3f by the conduction ratio limiting means 9 until the rotation speed of the motor 4 rises to the target rotation speed Ns. The rotational speed of the electric motor 4 can be raised to the target rotational speed Ns in a short time while being suppressed.
[0066]
(Example 5)
A fifth embodiment is an embodiment of the inverter device of the present invention shown in FIGS. 14 and 15, and controls when the motor 4 is started, that is, the power switching means 3 a to 3 b when the motor 4 is started by the conduction ratio limiting means 9. The continuity ratio of 3f is set to a predetermined value, and then the continuity ratio is gradually increased. The same components and effects as those of the first embodiment are denoted by the same reference numerals. Detailed description is omitted, and different parts are mainly described with reference to FIG.
[0067]
In the above configuration, the activation control of the electric motor 4 in the inverter device is a flow chart of steps 61 to 63 and steps 71 to 78 (hereinafter referred to as S61, S622, S63, S71,...) Shown in FIGS. -Follow the explanation. When the operation of the electric motor 4 is started in S61, soft start subroutine is performed in S62. As shown in the flowchart of FIG. 15, when the soft start subroutine is started in S71, the output from the conduction ratio limiting means 9 is prohibited in S72, and the conduction ratio set value is set. ds is set to ds 1 and output to the control means 5. When the control means 5 performs on / off control of the power switching means 3a to 3f with the conduction ratio set value ds1, AC power is supplied to the motor 4, and the rotor 4b rotates. Then, after a predetermined time has passed, it is determined in S73 whether or not the pulse signal of the hall IC 6a has been input a predetermined number of times. If not, in S74, the conduction ratio manipulated variable Δds is added to the previous conduction ratio setting value ds1, and a new The continuity ratio setting value ds is set. In S75, it is determined whether or not the conduction ratio set value ds exceeds the predetermined value dsmax. If not, the conduction ratio set value ds is output to the control means 5 in S76, and if it exceeds, the conduction ratio set value in S77. Is set to dsmax and output to the control means 5. Thereafter, after the elapse of the predetermined time t, it is determined in S73 whether or not the pulse signal of the hall IC 6a has been input a predetermined number of times. If it is determined that the predetermined number of times has been input, the soft start subroutine is terminated in S78, The rotational speed control subroutine of S63 of the flowchart shown in FIG. 14 is performed. Since this rotation speed control subroutine is the same as the rotation speed control subroutine described in the first embodiment according to the flowchart shown in FIG. 7, detailed description thereof will be omitted.
[0068]
As described above, by providing the soft start subroutine at the time of starting up the motor 4, the conduction ratio setting value at the time of starting up the motor 4 can be reduced, and the inverter circuit 3 and the three-phase winding 4a are overloaded. It is possible to prevent the current from flowing and prevent the output torque of the electric motor 4 from becoming excessive. Further, when the rotational speed of the electric motor 4 is detected by using the pulse signal of the hall IC 6a as in the present embodiment, the problem of responsiveness that the determination time becomes long when the rotational speed of the electric motor 4 is low. As a result, the start-up speed of the electric motor 4 may be slowed down. However, by performing the soft start subroutine shown in FIG. 15, the rotational speed detection and rotation are performed until the rotational speed of the electric motor 4 is increased to some extent. Since the conduction ratio set value is set unilaterally without performing numerical control, the startup speed of the electric motor 4 can be increased. At this time, since the conduction ratio maximum value dsmax is also set in the soft start subroutine, the current flowing through the inverter circuit 3 and the three-phase winding 4a can be suppressed to a predetermined value or less. It is possible to prevent an excessive torque from being applied to the output shaft.
[0069]
(Example 6)
Embodiment 6 is an embodiment of the inverter device of the present invention shown in FIG. 16, and the control at the time of starting the motor 4, that is, the conduction ratio of the power switching means 3a to 3f is increased from a predetermined value at the time of starting the motor 4. Then, the conduction ratio of the power switching means 3a to 3f is controlled by the conduction ratio limiting means 9, and then the conduction ratio of the power switching means 3a to 3f is controlled by the conduction ratio control means 8. Other components having the same configurations and effects as those of the first embodiment are denoted by the same reference numerals, detailed description thereof is omitted, and different portions are mainly described with reference to FIG.
[0070]
In the above configuration, start control of the electric motor 4 in the inverter device will be described in accordance with steps 81 to 84 (hereinafter referred to as S81 to S84) of the flowchart shown in FIG. When the operation of the electric motor 4 is started in S81, soft start subroutine is performed in S82. Since this soft start subroutine has the same structure as the flow described in accordance with the flowchart shown in FIG. 15 in the fifth embodiment, detailed description thereof will be omitted. When this soft start subroutine is completed, the activation control subroutine is executed in S83. This start control subroutine is the same as the flow described in the flow chart shown in FIG. 13 in the fourth embodiment, and rotates with the output torque of the motor 4 as large as possible up to the target rotational speed Ns. . After that, when the rotational speed of the electric motor 4 reaches the target rotational speed Ns, the flow described in the first embodiment in accordance with the flow chart shown in FIG. 7 by the conduction ratio control means 8 and the conduction ratio limiting means 9 in S84. The same speed control subroutine is performed.
[0071]
As described above, when the motor 4 is started, first, the soft start subroutine is performed, then the start control subroutine is performed, and finally the rotation speed control subroutine is performed. It is not necessary to detect the rotation speed by the detection means 7, and it can be avoided that the start-up of the electric motor 4 becomes unstable due to the slow detection speed of the rotation speed detection means 7. Further, the rotation speed detection means 7 can rotate with the output torque of the electric motor 4 as large as possible by the conduction ratio limiting means 9 from the rotation speed area where the rotation speed detection is high speed. Therefore, even if the rotation speed detection time at the low speed of the electric motor 4 is long, the electric motor 4 can be safely started up to the target rotation speed in a short time.
[0072]
The configuration of the inverter device, the rotational speed control method, and the motor start control method shown in the above embodiments are merely examples, and the present invention is not limited thereto.
[0073]
【The invention's effect】
As described above, according to the first aspect of the present invention, an AC power source, a rectifier circuit that converts the AC power source into a DC power source, and an inverter that converts the DC power source output from the rectifier circuit into an AC power source. An inverter circuit, an electric motor connected to the output side of the inverter circuit and having a permanent magnet in a rotor, control means for on / off control of power switching means constituting the inverter circuit, and Rotational speed detection means for detecting the rotational speed of the rotor, continuity ratio control means for receiving the output of the rotational speed detection means and controlling the continuity ratio of the power switching means, and continuity output from the continuity ratio control means Continuity ratio limiting means for controlling the maximum value of the ratio, the continuity ratio limiting means is an output of the rotational speed detection means If small is small, if large is large, Sets the maximum continuity ratio To prevent overcurrent Therefore, without detecting the current flowing through the three-phase winding or the inverter circuit of the motor, the current can be suppressed below a certain level, and the output torque of the motor can be suppressed below a certain level.
[0074]
According to the second aspect of the present invention, in the first aspect of the present invention, the voltage detecting means for detecting the DC voltage output from the rectifier circuit is provided, and the conduction ratio limiting means outputs the output of the voltage detecting means. Therefore, even if the output voltage of the rectifier circuit fluctuates due to voltage fluctuations of the AC power supply, etc., the three-phase winding of the motor Without detecting the flowing current, the current can be kept below a certain level, and the output torque of the motor can be kept below a certain level.
[0075]
According to the invention described in claim 3 of the present invention, in the invention described in claim 1 or 2, the conduction ratio limiting means is a power switching means according to the range of the detected rotational speed detected by the rotational speed detecting means. Since the maximum value of the conduction ratio is set, the output torque of the electric motor can be suppressed to a certain level or less with a simple configuration, and an inexpensive inverter device can be realized.
[0076]
According to the invention described in claim 4 of the present invention, in the invention described in any one of claims 1 to 3, the conduction ratio of the power switching means is controlled by the conduction ratio limiting means when the motor is started. After that, since the continuity ratio of the power switching means is controlled by the continuity ratio control means, the output torque of the motor can be obtained without detecting the current corresponding to the current of the three-phase winding of the motor. It can be rotated as large as possible. Therefore, the electric motor can be started up to the target rotational speed in a short time in a state where the output torque of the electric motor does not become excessive.
[0077]
According to the invention described in claim 5 of the present invention, in the invention described in any one of claims 1 to 3, when the motor is started, the conduction ratio of the power switching means is increased from a predetermined value, and thereafter Since the continuity ratio of the power switching means is controlled by the continuity ratio control means, even if the time until the rotation speed detection means is confirmed by the rotation speed detection means becomes long at a low speed of the electric motor, -Since the conduction ratio of the switching means is set unilaterally, the electric motor can be started up to a target rotational speed at a relatively high speed. Further, by setting the conduction ratio of the power switching means within a range where the output torque of the motor does not become excessive when the motor is started, a safe inverter device that can prevent the output shaft of the motor from being damaged can be realized.
[0078]
According to the invention described in claim 6 of the present invention, in the invention described in any one of claims 1 to 3, when the motor is started, the conduction ratio of the power switching means is increased from a predetermined value, and thereafter Since the continuity ratio of the power switching means is controlled by the continuity ratio limiting means, and then the continuity ratio of the power switching means is controlled by the continuity ratio control means, the rotational speed of the motor at low speed Since it is not necessary to detect and the motor can be rotated by increasing the output torque of the motor as much as possible from the rotation speed range where the rotation speed can be detected by the conduction ratio limiting means, the rotation speed detecting means is at a low speed of the motor. Even if the time for detecting the rotational speed is long, the electric motor can be started up to the target rotational speed in a short time and safely.
[Brief description of the drawings]
FIG. 1 is a block circuit diagram of an inverter device according to a first embodiment of the present invention.
FIG. 2 is a waveform diagram of each part during operation of the inverter device.
FIG. 3 is a characteristic graph of output torque-current peak of an electric motor in each embodiment of the inverter device of the present invention.
FIG. 4 is a graph showing the output torque-rotation speed characteristic of the motor in each embodiment of the inverter device of the present invention.
FIG. 5 is a graph for setting the motor rotation speed-conduction ratio maximum value of the conduction ratio limiting means in Embodiment 1 of the inverter device of the present invention;
FIG. 6 is a characteristic graph of motor output torque-rotation speed during control of the inverter device.
FIG. 7 is a flowchart of a motor speed control subroutine in the inverter device.
FIG. 8 is a longitudinal sectional view of an electric washing machine equipped with the inverter device.
FIG. 9 is a graph for setting the maximum motor rotation speed-conduction ratio of the conduction ratio limiting means in the second embodiment of the inverter device of the present invention;
FIG. 10 is a characteristic graph of output torque-rotation speed of an electric motor during control of the inverter device.
FIG. 11 is a block circuit diagram of Embodiment 3 of the inverter device of the present invention.
FIG. 12 is a flowchart for controlling the rotational speed of an electric motor in Embodiment 4 of the inverter device of the present invention;
FIG. 13 is a flowchart of a start-up control subroutine of an electric motor during control of the inverter device.
FIG. 14 is a flowchart for controlling the rotational speed of the electric motor in the fifth embodiment of the inverter device of the present invention;
FIG. 15 is a flowchart of a soft start subroutine of an electric motor during control of the inverter device.
FIG. 16 is a flowchart of motor start-up and rotation speed control in Embodiment 6 of the inverter apparatus of the present invention;
[Explanation of symbols]
1 AC power supply
2 Rectifier circuit
3 Inverter circuit
4 Electric motor
5 Control means
6 Position detection means
7 Number of rotation detection means
8 conduction ratio control means
9, 32 conduction ratio limiting means

Claims (6)

交流電源と、前記交流電源を直流電源に変換する整流回路と、前記整流回路の出力する直流電源を交流電源に変換するインバ−タ回路と、前記インバ−タ回路の出力側に接続し、回転子に永久磁石を有する電動機と、前記インバ−タ回路を構成するパワ−スイッチング手段をオンオフ制御する制御手段と、前記電動機の回転子の回転数を検知する回転数検知手段と、前記回転数検知手段の出力を受けて前記パワ−スイッチング手段の導通比を制御する導通比制御手段と、前記導通比制御手段の出力する導通比の最大値を制御する導通比制限手段を備え、前記導通比制限手段は前記回転数検知手段の出力が小なら小、大なら大に、導通比の最大値を設定し、電流を一定以下に抑え過電流を防止するインバ−タ装置。An AC power source, a rectifier circuit that converts the AC power source into a DC power source, an inverter circuit that converts a DC power source output from the rectifier circuit into an AC power source, and an output side of the inverter circuit that rotates. An electric motor having a permanent magnet in the child, a control means for controlling on / off of the power switching means constituting the inverter circuit, a rotational speed detecting means for detecting the rotational speed of the rotor of the electric motor, and the rotational speed detection A conduction ratio control means for controlling the conduction ratio of the power switching means in response to the output of the means; and a conduction ratio limiting means for controlling the maximum value of the conduction ratio output by the conduction ratio control means, the conduction ratio restriction The means is an inverter device for setting the maximum value of the conduction ratio to be small if the output of the rotational speed detection means is small and large if large, and to prevent overcurrent by keeping the current below a certain level . 整流回路の出力する直流電圧を検知する電圧検知手段を備え、導通比制限手段は前記電圧検知手段の出力を受けてパワ−スイッチング手段の導通比の最大値を補正する請求項１記載のインバ−タ装置。  2. An inverter according to claim 1, further comprising voltage detection means for detecting a DC voltage output from the rectifier circuit, wherein the conduction ratio limiting means receives the output of the voltage detection means and corrects the maximum value of the conduction ratio of the power switching means. Device. 導通比制限手段は、回転数検知手段が検知した検知回転数の範囲に応じてパワ−スイッチング手段の導通比の最大値を設定する請求項１または２記載のインバ−タ装置。  3. The inverter device according to claim 1, wherein the continuity ratio limiting means sets the maximum value of the continuity ratio of the power switching means in accordance with a range of the detected rotational speed detected by the rotational speed detecting means. 電動機の起動時には、導通比制限手段によりパワ−スイッチング手段の導通比を制御し、その後は導通比制御手段によりパワ−スイッチング手段の導通比を制御する構成にした請求項１〜３のいずれか１項に記載のインバ−タ装置。  4. The apparatus according to claim 1, wherein when the motor is started, the conduction ratio of the power switching means is controlled by the conduction ratio limiting means, and thereafter the conduction ratio of the power switching means is controlled by the conduction ratio control means. The inverter device according to item. 電動機の起動時には、パワ−スイッチング手段の導通比を所定値より増加させ、その後導通比制御手段によりパワ−スイッチング手段の導通比を制御する構成にした請求項１から３のいずれか１項に記載のインバ−タ装置。  4. The structure according to claim 1, wherein at the time of starting the electric motor, the conduction ratio of the power switching means is increased from a predetermined value, and then the conduction ratio of the power switching means is controlled by the conduction ratio control means. Inverter device. 電動機の起動時には、パワ−スイッチング手段の導通比を所定値より増加させ、その後は導通比制限手段によりパワ−スイッチング手段の導通比を制御し、さらにその後は導通比制御手段によりパワ−スイッチング手段の導通比を制御する構成にした請求項１から３のいずれか１項に記載のインバ−タ装置。  At the time of starting the motor, the conduction ratio of the power switching means is increased from a predetermined value, and thereafter the conduction ratio of the power switching means is controlled by the conduction ratio limiting means, and thereafter, the power switching means is controlled by the conduction ratio control means. The inverter device according to any one of claims 1 to 3, wherein the conduction ratio is controlled.
JP34509198A 1998-12-04 1998-12-04 Inverter device Expired - Fee Related JP4161436B2 (en)

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JP2002247879A (en) * 2001-02-21 2002-08-30 Matsushita Electric Ind Co Ltd Inverter device and washing machine using it
JP4167863B2 (en) * 2002-07-30 2008-10-22 株式会社日立製作所 Synchronous motor control device and equipment using the same
JP2005287202A (en) * 2004-03-30 2005-10-13 Mitsubishi Fuso Truck & Bus Corp Motor controller
JP2005287259A (en) * 2004-03-31 2005-10-13 Mitsubishi Fuso Truck & Bus Corp Motor controller
JP2007110788A (en) * 2005-10-11 2007-04-26 Nsk Ltd Electromotive steering device
JP5250982B2 (en) * 2006-09-27 2013-07-31 株式会社リコー Motor control apparatus, motor control method, motor control program, and image forming apparatus
JP2011120330A (en) * 2009-12-01 2011-06-16 Mitsubishi Electric Corp Inverter device and air conditioner with the same
FR3004871B1 (en) * 2013-04-19 2017-01-13 Valeo Systemes De Controle Moteur METHOD FOR ELECTRICALLY POWERING AN ELECTRIC MOTOR, ASSOCIATED COMPUTER PROGRAM, DEVICE FOR CONTROLLING AN INVERTER AND ELECTRICAL ROTATING MACHINE

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