JP2004208371A - Current detector for motor, and current controller using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To compute the estimate of the output torque of a motor by making the profile of the current waveform for one cycle in electric angle, and using not only an instantaneous current value but also the profile of this current waveform. <P>SOLUTION: This system detects a current flowing to the winding of the motor with a current sensor 60, and samples the output of the current sensor 60 covering one cycle in electric angle. At sampling, this performs the sampling while judging the angle of a rotor at sampling, and gets the sampling values for one cycle in electric angle and the angle θ of a rotor at sampling without excess and deficiency for one cycle in electric angle. The sampling value for one cycle in electric angle and the angle of the rotor at sampling show the profile of the waveform of a current flowing to the winding of the motor. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

処理３２、３３では、処理３１と同様の処理をＶ相、Ｗ相について実施し、Ｖ相出力トルク推定値Ｔｖ、Ｗ相出力トルク推定値Ｔｗを算出する。
【００２１】
【数２】

【００２２】
【数３】

（θｕ_ｋ、θｖ_ｋ、θｗ_ｋ：Ｕ相、Ｖ相、Ｗ相のサンプリング時の回転子角度、ｉｕ_ｋ、ｉｖ_ｋ、ｉｗ_ｋ：Ｕ相、Ｖ相、Ｗ相の電流のサンプリング値、 Ｌｕ、Ｌｖ、Ｌｗ：Ｕ相、Ｖ相、Ｗ相の巻線のインダクタンス）
インダクタンスは回転子角度θに応じて変化するため、θをパラメータとしたｄＬｕ／ｄθ、ｄＬｖ／ｄθ、ｄＬｗ／ｄθをあらかじめ計測して、マップ化しておく。
【００２３】
次に処理３４において、電気角１周期分の出力トルク推定値Ｔｅを算出する。Ｔｅは以下の式で表される。
【００２４】
【数４】

このように回転子角度θに基づく出力トルク推定値Ｔｅを計算式を用いて、サンプリングした所定の角度およびサンプリング値からダイレクトに決定できるので、これにかかる処理時間を短くできる。
【００２５】
次に処理３５から３８において、トルク指令値Ｔ＊と出力トルク推定値Ｔｅが等しい場合は、そのまま割り込み処理３０を終了する。出力トルク推定値Ｔｅがトルク指令値Ｔ＊より大きい場合は次の電気角周期の励磁開始角度指令値θｏｎ＊を今回より遅らせ、出力トルク推定値Ｔｅがトルク指令値Ｔ＊より小さい場合は次の電気角周期の励磁開始角度指令値θｏｎ＊を今回より早める。このように出力トルク推定値Ｔｅと、トルク指令値Ｔ＊との差に基づいて所望のトルクとなるように励磁開始角度指令値θｏｎ＊を変更し、インバータから巻線に加える巻線電圧波形を調整するので、精度良く所望のトルクを発生することができる。
【００２６】
本第１の実施の形態をブロック図で表したものが図４である。この第１の実施の形態は電動機６１及び電流制御装置５０で構成されており、電流制御装置５０は電流センサ６０の出力を読み込む電流サンプル部５４、電動機巻線の電流を検知する電流センサ６０及び回転子角度を検知する角度位置センサ６３から構成される電流検出装置、電動機６１を駆動するインバータ５９、インバータ電源６２、トルク指令値生成部５７、インバータ電圧の印加タイミングを指令する励磁角度指令値生成部５１、インバータ素子制御信号を生成するインバータ制御信号生成部５３、出力トルク推定値Ｔｅを算出するトルク推定値生成部５５、トルク指令値Ｔ＊と出力トルク推定値Ｔｅの差を演算する加算器５８、加算器５８の出力を入力する比例・積分制御部５６、励磁開始角度指令値θｏｎ＊と比例・積分制御部の出力の差を演算する加算器５２、角度位置センサ６３の出力から回転子角速度ωを演算する速度演算部６４から構成されている。ここで電流波形輪郭作成手段は電流サンプル部５４で構成され、波形調整手段は加算器５２、５８、比例・積分制御部５６、インバータ制御信号生成部５３等から構成されている。
【００２７】
図２の電流センサ出力をサンプリングする割り込み処理１０は、電流サンプル部５４で実施する。図３の電流制御を実施する割り込み処理３０はトルク推定値生成部５５で実施する。
【００２８】
一般に１パルス制御のＳＲモータでは、回転子角速度とインバータ入力電圧とトルク指令値をパラメータとしたマップで励磁開始角度指令値θｏｎ＊と励磁終了角度指令値θｏｆｆ＊を決定する方法がとられるが、本第１の実施の形態ではトルク指令値Ｔ＊と出力トルク推定値Ｔｅとの差を励磁開始角度指令値θｏｎ＊にフィードフォワ−ドして、より精度の高いトルク出力が得られる。
【００２９】
なお、変化させる指令値は励磁開始角度指令値θｏｎ＊とは限らない。同様の方法で励磁終了角度θｏｆｆ＊を調整の対象としてもよいし、励磁開始角度指令値θｏｎ＊と励磁終了角度指令値θｏｆｆ＊の両方を調整の対象としてもよい。またこれらのどの指令値を変化させるかは、システムの効率が最適になるように選択するのが望ましく、回転子速度や入力電圧等の運転状況に応じて切り替えてもよい。
【００３０】
図５は励磁終了角度指令値θｏｆｆ＊を調整の対象とした場合のブロック図である。図４との違いは、比例・積分制御部７６の出力と励磁終了角度指令値θｏｆｆ＊との差を加算器７２で演算し、インバータ制御信号生成部５３に入力している点である。図６は励磁開始角度指令値θｏｎ＊と励磁終了角度指令値θｏｆｆ＊の両方を調整の対象とした場合のブロック図である。図４との違いは、比例・積分制御部９６の出力が２系統あり、励磁開始角度指令値θｏｎ＊との差および励磁終了角度指令値θｏｆｆ＊との差を加算器５２、７２で演算し、インバータ駆動信号生成部５３に入力している点である。
【００３１】
このように出力トルク推定値Ｔｅと、トルク指令値Ｔ＊との差に基づいて励磁開始角度指令値θｏｎ＊もしくは励磁終了角度指令値θｏｆｆ＊あるいは両方を調整するので、電動機の温度上昇等により運転中に巻線抵抗が変化しても、所望の電流波形を出力することができる。
【００３２】
更に、電流センサ出力を電気角１周期にサンプリングする頻度を少なくし、電流波形の輪郭を完成させるのに複数周期を要しても構わない。ただし電流波形の輪郭が完成するまでは、回転子角速度、インバータ入力電圧、トルク指令値のそれぞれが一定で、かつ電流のサンプリングのタイミングは回転子角度に応じて設定する等の条件があるが、第３の実施の形態から第４の実施の形態で説明する処理を本第１の実施の形態と組み合わせることで実現可能である。電流サンプリングの頻度を少なくできれば、応答時間の遅い安価なサンプリング装置でも問題なく使用できる。
【００３３】
次に第２の実施の形態を図７から図９を用いて説明する。
【００３４】
図７はインバータ入力電圧指令値Ｖｉｎ＊の調整を示すタイムチャート、図８はインバータ入力電圧指令値Ｖｉｎ＊の調整を示すフローチャート、図９はインバータ入力電圧指令値Ｖｉｎ＊の調整を示すブロック図である。
【００３５】
本第２の実施の形態は、一定周期で電動機の巻線に流れる電流値を電流センサにより取得し、その電流センサ出力を電気角１周期に複数回サンプリングし、そのサンプリング値とサンプリングした時の回転子角度を電気角１周期分蓄えることにより電気角１周期分の電流波形の輪郭を作成し、その輪郭から算出した電気角１周期分の出力トルク推定値Ｔｅと、トルク指令値Ｔ＊を比較し、次回のインバータ入力電圧指令値Ｖｉｎ＊を調整することを特徴とする。
【００３６】
まず本第２の実施の形態の概要を図７に示す。図７は、ＳＲモータの回転子角度、Ｕ相巻線電流、電流センサ出力をサンプリングする割り込み処理１０、出力トルク推定値Ｔｅを演算する割り込み処理１１０、トルク指令値Ｔ＊、出力トルク推定値Ｔｅ、インバータ入力電圧指令値Ｖｉｎ＊の時間変化を表している。
【００３７】
まず電流センサ出力をサンプリングする割り込み処理を一定周期で実行しサンプリング値を取得する。サンプリング値と、サンプリング時の回転子角度をＲＡＭ等の記憶装置に記憶する。続いて、回転子電気角１周期につき１回実行する割り込み処理１１０において、電気角１周期分のサンプリング値とサンプリング時の回転子角度を読み出し、電気角１周期分の出力トルク推定値Ｔｅを算出する。続いて、トルク指令値Ｔ＊と出力トルク推定値Ｔｅの差に基づいて、次の電気角周期におけるインバータ入力電圧指令値Ｖｉｎ＊を決定する。
【００３８】
続いて、本第２の実施の形態の詳細を図８のフローチャートに沿って説明する。
【００３９】
図８において、割り込み処理１１０から処理３６までは第１の実施の形態の図３と全く同じであるので処理１１７と１１８について図９を用いて説明する。
【００４０】
まず電気角ｍ周期目において、トルク指令値生成部１３５から出力されるトルク指令値Ｔ＊から、図８の処理３４（図９のトルク推定値生成部５５）で計算した電気角１周期分の出力トルク推定値Ｔｅを引いた値を比例・積分制御部１３６に入力し、インバータ入力電圧の補償値Ｖｃｏｍｐを求める。インバータ入力電圧Ｖｉｎのサンプリング値Ｖｉｎｓを記憶し、ｍ−１周期目のインバータ入力電圧を出力する電圧値保存部１３７の出力値Ｖ_ｍ−１にＶｃｏｍｐを加えて、ｍ＋１周期目のインバータ入力電圧指令値Ｖｉｎ_ｍ＋１＊とする。
【００４１】
一般に１パルス制御では、回転子角速度とインバータ入力電圧とトルク指令値をパラメータとしたマップで励磁開始角度指令値θｏｎ＊と励磁終了角度指令値θｏｆｆ＊を決定する方法がとられるが、本第２の実施の形態では更にインバータ入力電圧Ｖｉｎを調整して、より精度の高いトルク出力が得られる。また、ＤＣ−ＤＣコンバータ等の、直流電圧変換手段が必要なものの、インバータ入力電圧を必要最低限に抑えられるので、インバータ素子のスイッチング損失を減少させることができる。
【００４２】
次に第３の実施の形態を図１０を用いて説明する。
【００４３】
図１０は電動機の回転子角速度の変化が所定値以下の場合に励磁開始角度θｏｎ＊を調整するフローチャート。
【００４４】
本第３の実施の形態は、第１の実施の形態もしくは第２の実施の形態と組み合わせて用いられ、回転子角速度、インバータ入力電圧およびトルク指令値の変化が所定値以下であることを検知して出力トルク推定値Ｔｅを求め、励磁開始角度θｏｎ＊を調整することを特徴とする。
【００４５】
次に電動機の回転子角速度の変化が所定値以下であることを検知する方法を述べる。
【００４６】
図１０は出力トルク推定値Ｔｅ算出処理のフローチャートを表している。このフローチャートは第１の実施の形態の図３に破線部分の処理１５０を追加したものである。
【００４７】
処理１５０では、電流センサ出力をサンプリング中の電気角１周期中の回転子の加速度の絶対値｜ａ｜を求め、｜ａ｜があらかじめ定めた許容加速度ａ_ｍａｘ以下であった場合に限り、出力トルク推定値Ｔｅの演算および励磁角度指令値の調整（処理３１から３８）を実行する。
【００４８】
加速度ａの値は次のような手順で求める。
【００４９】
Ｕ相電流のサンプリング時の回転子角度ｎ個（θｕ_１、θｕ_２、…、θｕ_ｎ−１、θｕ_ｎ）のそれぞれ隣り合う位置の間の速度ｎ−１個（ｖｕ_１、ｖｕ_２、…、ｖｕ_ｎ−２、ｖｕ_ｎ−１）を求める。
【００５０】
ｖｕ_１＝（θｕ_２−θｕ_１）／ｔ
ｖｕ_２＝（θｕ_３−θｕ_２）／ｔ
…
ｖｕ_ｎ−１＝（θｕ_ｎ−θｕ_ｎ−１）／ｔ （５）
（ｔ：サンプリング周期）
更に、これら速度の値からｎ−２個（ａｕ_１、ａｕ_２、…、ａｕ_ｎ−３、ａｕ_ｎ−２）の加速度を求める。
【００５１】
ａｕ_１＝（ｖｕ_２−ｖｕ_１）／ｔ
ａｕ_２＝（ｖｕ_３−ｖｕ_２）／ｔ
…
ａｕ_ｎ−１＝（ｖｕ_ｎ−１−ｖｕ_ｎ−２）／ｔ （６）
これらｎ−２個の加速度のうち絶対値の最大値を加速度｜ａ｜とする。
【００５２】
なお、ａの求め方はこの方法には限らない。本第３の実施の形態ではＵ相電流サンプリング時の回転子位置を使用したが、Ｖ相もしくはＷ相の回転子位置でも構わない。また、算出したｎ−２個の加速度のうち絶対値の最大値を｜ａ｜としたが、ｎ−２個の加速度の平均値の絶対値を｜ａ｜としてもよい。
【００５３】
回転子角速度に限らず、インバータ入力電圧やトルク指令値に対しても同様の処理を実施できる。このように回転子角速度、インバータ入力電圧およびトルク指令値の定常状態における電流センサ出力のサンプリング値から得られる電流波形の輪郭に基づいて出力トルク推定値Ｔｅを求めるので、精度よく出力トルク推定値Ｔｅを算出することができる。
【００５４】
第４の実施の形態を図１１および図１２を用いて説明する。
【００５５】
図１１は電気角度複数周期分から電流波形の輪郭を作成するタイムチャート、図１２は電気角度複数周期の電流をサンプリングするフローチャートである。
【００５６】
本第４の実施の形態は、第１の実施の形態もしくは第２の実施の形態と組み合わせて用いられ、電気角複数周期分の電流センサ出力のサンプリング値と、この時の回転子角度から電気角１周期分の電流波形の輪郭を作成することを特徴とする。
【００５７】
まず本第４の実施の形態の概要を図１１を用いて説明する。図１１は、ＳＲモータの回転子角度、Ｕ相巻線電流、電流センサ出力をサンプリングする割り込み処理１９０、電流波形の輪郭と、出力トルク推定値Ｔｅを演算する割り込み処理２１０、電流波形の輪郭の時間変化を表している。
【００５８】
まず割り込み処理１９０は回転子が所定の角度に到達した時に実行し、電流センサ出力をサンプリングし、サンプリング値とサンプリング時の回転子角度をＲＡＭ等の記憶装置に記憶する。
【００５９】
続いて、回転子電気角１周期につき１回実行する割り込み処理２１０において、電気角１周期分のサンプリング値とサンプリング時の回転子角度を読み出し、電気角１周期分の出力トルク推定値Ｔｅを算出する。続いて、トルク指令値Ｔ＊と出力トルク推定値Ｔｅの差に基づいて、次の電気角周期における励磁開始角度指令値θｏｎ＊を決定する。
【００６０】
次に本第４の実施の形態の詳細を図１２を用いて説明する。
【００６１】
図１２のフローチャートは、電動機の電流制御装置を構成するマイコンの割り込み処理で、電流センサ出力のサンプリングを実施する処理を表している。この割り込み処理１９０は回転子角度に同期して実行する。処理１９１において、Ｕ相電流をサンプリングし、サンプリングした電流値ｉｕ_ｎと、サンプリング時の回転子角度θｕ_ｎをＲＡＭ等の記憶装置に記憶する。処理１９２、１９３ではＶ相とＷ相について、処理１９１と同様の処理を行う。処理１９４から１９９では、次回の電流サンプリングを実行する回転子角度θｕ_ｎ＋１、θｖ_ｎ＋１、θｗ_ｎ＋１を決定する。決定方法は以下の式から求める。
θｕ_ｎ＋１＝θｕ_１＋（ｎ＋１）α
θｖ_ｎ＋１＝θｖ_１＋（ｎ＋１）α
θｗ_ｎ＋１＝θｗ_１＋（ｎ＋１）α
（α：位置センサが検出できる角度の最小単位）
また、ｎに例えば１０などの上限値ｐを設け、上限に達した次の周期の電流サンプリング角度をθｕ_１、θｖ_１、θｗ_１にリセットする。
【００６２】
このように電気角１周期毎に電流センサ出力をサンプリングする回転子角度をずらすことによって、複数周期のサンプリング値から、電気角１周期分の電流の輪郭を作成できる。
【００６３】
次に、図１１の割り込み処理２１０において、割り込み処理１９０でサンプリングしこれまで取得した電気角１周期分のサンプリング値を用いて出力トルク推定値Ｔｅを算出し、トルク指令値Ｔ＊と比較して、励磁開始角度指令値θｏｎ＊等を変更する。本割り込み処理２１０の詳細は、実施例１の割り込み処理３０や、実施例２の割り込み処理１１０と同様である。
【００６４】
この複数周期のサンプリング値から、電気角１周期分の電流の輪郭を作成することにより、電気角１周期あたりのサンプリング回数が少ない高速回転時においても出力トルク推定値Ｔｅを算出することが可能となり、あらゆる回転速度で第１の実施の形態および第２の実施の形態を適用できる。
【図面の簡単な説明】
【図１】本発明の第１の実施の形態の励磁開始角度指令値調整を示すタイムチャート。
【図２】本発明の第１の実施の形態のサンプリングを示すフローチャート。
【図３】本発明の第１の実施の形態の励磁開始角度指令値調整を示すフローチャート。
【図４】本発明の第１の実施の形態の励磁開始角度指令値調整を示す電流制御装置のブロック図。
【図５】本発明の第１の実施の形態の励磁終了角度指令値調整を示す電流制御装置のブロック図。
【図６】本発明の第１の実施の形態の励磁開始角度指令値および励磁終了角度指令値調整を示す電流制御装置のブロック図。
【図７】本発明の第２の実施の形態のインバータ入力電圧指令値調整を示すタイムチャート。
【図８】本発明の第２の実施の形態のインバータ入力電圧指令値調整を示すフローチャート。
【図９】本発明の第２の実施の形態のインバータ入力電圧指令値調整を示す電流制御装置のブロック図。
【図１０】本発明の第３の実施の形態の励磁開始角度指令値調整を示すフローチャート。
【図１１】本発明の第４の実施の形態の電流波形の輪郭形成を示すフローチャート。
【図１２】本発明の第４の実施の形態のサンプリングを示すフローチャート。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention has an angular position sensor for detecting the relative angular position of the stator and the rotor, and outputs the current of the winding wound on the stator from the current sensor output based on the rotor angle obtained from the angular position sensor. The present invention relates to a current detection device for a motor for detecting a current, and a current control device using the detection device.
[0002]
[Prior art]
Non-Patent Document "Switched Reluctance Motors and Their Control Page99~100 T.J.E Miller (Lucas Professor in Power Electronics / SPEED Laboratory / University of Glasgow) Magna Physics Publishing and Clarendon Press · OXFORD 1993".
[0003]
To control the rotor speed of the switched reluctance motor shown in the above non-patent document, a motor torque is converted into a rotor speed, and a pulse proportional to an error between the rotor speed and a reference rotor speed is used. A pulse train having a width is generated, and the pulse train controls a rectangular wave voltage for driving a motor.
[0004]
[Problems to be solved by the invention]
In this prior art, the pulse width is determined in accordance with the error between the rotor speed and the reference rotor speed, so that if the resistance or inductance of the winding changes due to temperature characteristics, the desired rotation speed is maintained. In some cases, torque ripple was not possible.
[0005]
The present invention has been made to solve the above-described problems, and has as its object to provide a current detection device for a motor capable of stably supplying an output torque of the motor, and a current control device using the detection device. I do.
[0006]
[Means for Solving the Problems]
According to the present invention, the current of the winding wound on the stator is detected from the current sensor output based on the rotor angle obtained from the angle position sensor that detects the relative angular position of the stator and the rotor.
[0007]
【The invention's effect】
According to the present invention, the output torque estimated from the current contour waveform and the winding voltage waveform applied to the motor are adjusted based on the difference between the torque command value and the desired current based on the difference between the torque command value. Can occur.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings described below, components having the same function are denoted by the same reference numerals, and repeated description thereof will be omitted.
[0009]
The first embodiment will be described with reference to FIGS. 1 to 6 by taking a SR motor having three phases of U-phase, V-phase, and W-phase windings as an example. FIG. 1 is a time chart showing a method of changing the current sampling and excitation start angle command value θon * in the first embodiment, FIG. 2 is a flowchart of sampling the current, and FIG. 3 is a calculation of an estimated output torque Te and the start of excitation. 4 is a flowchart showing the adjustment of the angle command value θon *, FIG. 4 is a block diagram of a current control device showing the adjustment of the excitation start angle command value θon *, and FIG. 5 is a block diagram of the current control device showing the adjustment of the excitation end angle command value θoff *. FIG. 6 is a block diagram of the current control device showing adjustment of both the excitation start angle command value θon * and the excitation end angle command value θoff *.
[0010]
In the first embodiment, a value of a current flowing through a winding of a motor is obtained by a current sensor at a constant cycle, and the output of the current sensor is sampled a plurality of times during one cycle of an electrical angle. By storing the rotor angle for one cycle of the electrical angle, a contour of the current waveform for one cycle of the electrical angle is created, and the output torque estimated value Te for one cycle of the electrical angle calculated from the contour and the torque command value T * are calculated. It is characterized by comparing and adjusting the next command value and controlling the current flowing through the winding.
[0011]
First, an outline of the first embodiment will be described with reference to FIG. FIG. 1 shows an interrupt process 10 for sampling the rotor angle of the SR motor, the U-phase winding current, and the current sensor output, an interrupt process 30 for calculating the output torque estimated value Te, a torque command value T *, an output torque estimated value Te, It shows a temporal change of the excitation start angle command value θon *.
[0012]
First, the interrupt processing 10 is executed at a fixed cycle, and the sampling value obtained by sampling the output of the current sensor and the relative angular position (rotor angle) of the rotor with respect to the stator at the time of sampling are stored in a storage device such as a RAM.
[0013]
Subsequently, in an interrupt process 30 executed once per rotor electrical angle cycle, a sampling value for one electrical angle cycle and a rotor angle at the time of sampling are read, and an output torque estimated value Te for one electrical angle cycle is calculated. I do. Subsequently, based on the difference between the torque command value T * and the output torque estimated value Te, the excitation start angle command value θon * in the next electrical angle cycle is determined.
[0014]
Next, details of the first embodiment will be described with reference to FIGS.
[0015]
The flowchart of FIG. 2 shows a process of sampling the output of the current sensor in the interrupt process of the microcomputer constituting the current control device 50 of the electric motor. The interrupt processing 10 is executed at a constant period in the first embodiment, but may be executed at a predetermined angle synchronized with the rotor angle. A sampling method synchronized with the rotor angle will be described in a fourth embodiment.
[0016]
In process 11, and stores the sampling values iu _n sampling the U-phase current, the rotor angle .theta.u _n the time of sampling in a storage device such as a RAM. In processes 12 and 13, the same process as process 11 is performed for the V phase and the W phase. When a plurality of AD converters having a sampling function are provided, two or three of the processes 11 to 13 may be executed simultaneously. Next, a location for storing the next sample current value and the rotor angle in the storage device is determined. In order to calculate the output torque estimated value Te described later, it is necessary to accurately create the contour of the current waveform for one electrical angle cycle. It is necessary to memorize it. Therefore, the processes 14 to 16 for storing data for one cycle of the electrical angle from the electrical angle of 0 to 360 degrees are performed as follows. A rotor angle .theta.w _n stored in the current processing 13, the absolute value of the stored difference rotor angle .theta.w _n-1 in the previous process _{13 | θw n -θw n-1} | look, | θw _n -θw _n-1 | is the case d (eg d = 180) smaller by substituting n + 1 to n to end the interrupt process _{10, | θw n -θw n-} 1 | if is more than d assigns 1 to n Then, the interrupt processing 10 ends. By doing so, a sudden change in the output value of the angle position sensor at a rotor electrical angle of 0 degree is detected, and the numerical value n that determines the storage location of the information is reset to 1, so that the sampling value and the rotor angle are equal to one cycle of the electrical angle. You can remember minutes. The processes 14, 15, and 16 are also performed for the U phase and the V phase. As described above, by accurately acquiring the sampling value of the current sensor output and the rotor angle at the time of sampling over one cycle of the electrical angle, the sampling value for one cycle of the electrical angle at the acquired rotor angle becomes the contour of the current waveform. Is shown. Since the average current value and the like can be calculated from the contour of the current waveform of one electrical angle, feedback control using information other than the instantaneous current is also possible.
[0017]
The flowchart of FIG. 3 is an interrupt process of the microcomputer constituting the electric current control device 50 of the electric motor, calculates the output torque estimated value Te for one cycle of the electric angle, adjusts the excitation start angle command value θon *, This shows a process for controlling the flowing current.
[0018]
This interrupt processing 30 is executed for each electrical angle cycle. In the first embodiment, the interrupt processing 30 is started in synchronization with the electrical angle of the rotor becoming 0 degrees. The frequency of execution is desirably one or more per one cycle of the electrical angle. Regarding the execution timing of the interrupt processing, the processing may be started at a predetermined angle in synchronization with the electrical angle as in the first embodiment, or may be started at a fixed period asynchronously with the angle. Is also good.
[0019]
First, in a process 31, an output torque estimated value Tu for one U-phase electrical angle cycle is calculated using a sampling value for one electrical angle cycle and the rotor angle at the time of sampling.
[0020]
(Equation 1)

In the processes 32 and 33, the same process as the process 31 is performed for the V phase and the W phase, and the estimated V-phase output torque Tv and the estimated W-phase output torque Tw are calculated.
[0021]
(Equation 2)

[0022]
[Equation 3]

_{(Θu k, θv k, θw} k: U phase, V phase, the rotor angle at the time of sampling of the _{W-phase, iu k, iv k, iw} k: U -phase, V-phase, the sampling value of the W-phase current, Lu , Lv, Lw: U-phase, V-phase, W-phase winding inductance)
Since the inductance changes according to the rotor angle θ, dLu / dθ, dLv / dθ, and dLw / dθ using θ as a parameter are measured in advance and mapped.
[0023]
Next, in process 34, the output torque estimated value Te for one cycle of the electrical angle is calculated. Te is represented by the following equation.
[0024]
(Equation 4)

As described above, since the output torque estimated value Te based on the rotor angle θ can be directly determined from the sampled predetermined angle and the sampled value using the calculation formula, the processing time required for this can be shortened.
[0025]
Next, when the torque command value T * and the output torque estimated value Te are equal in the processings 35 to 38, the interruption processing 30 is terminated. When the output torque estimated value Te is larger than the torque command value T *, the excitation start angle command value θon * of the next electrical angle cycle is delayed from this time, and when the output torque estimated value Te is smaller than the torque command value T *, the next The excitation start angle command value θon * of the electric angle cycle is earlier than this time. As described above, the excitation start angle command value θon * is changed based on the difference between the output torque estimated value Te and the torque command value T * so as to obtain a desired torque, and the winding voltage waveform applied from the inverter to the winding is changed. Since the adjustment is performed, a desired torque can be generated with high accuracy.
[0026]
FIG. 4 is a block diagram showing the first embodiment. The first embodiment includes a motor 61 and a current control device 50. The current control device 50 reads the output of the current sensor 60, a current sensor 60 that detects the current of the motor winding, and A current detection device including an angle position sensor 63 for detecting a rotor angle; an inverter 59 for driving the electric motor 61; an inverter power supply 62; a torque command value generation unit 57; and an excitation angle command value generation for commanding the inverter voltage application timing Unit 51, an inverter control signal generator 53 for generating an inverter element control signal, a torque estimated value generator 55 for calculating an output torque estimated value Te, and an adder for calculating a difference between the torque command value T * and the output torque estimated value Te. 58, a proportional / integral control unit 56 for inputting the output of the adder 58, an excitation start angle command value θon * and a proportional / integral control unit Adder 52 for calculating a difference between the outputs, and an output of the angular position sensor 63 from the speed calculator 64 for calculating a rotor angular velocity omega. Here, the current waveform contour creating means is constituted by a current sampling section 54, and the waveform adjusting means is constituted by adders 52 and 58, a proportional / integral control section 56, an inverter control signal generating section 53 and the like.
[0027]
The interrupt processing 10 for sampling the output of the current sensor in FIG. The interrupt processing 30 for performing the current control in FIG. 3 is performed by the torque estimated value generation unit 55.
[0028]
Generally, in a one-pulse control SR motor, a method is used in which the excitation start angle command value θon * and the excitation end angle command value θoff * are determined using a map using the rotor angular velocity, the inverter input voltage, and the torque command value as parameters. In the first embodiment, the difference between the torque command value T * and the output torque estimated value Te is fed forward to the excitation start angle command value θon *, so that a more accurate torque output can be obtained.
[0029]
The command value to be changed is not limited to the excitation start angle command value θon *. In the same manner, the excitation end angle θoff * may be adjusted, or both the excitation start angle command value θon * and the excitation end angle command value θoff * may be adjusted. It is desirable to select which of these command values to change so as to optimize the efficiency of the system, and it may be switched according to the operating conditions such as the rotor speed and the input voltage.
[0030]
FIG. 5 is a block diagram when the excitation end angle command value θoff * is to be adjusted. The difference from FIG. 4 is that the difference between the output of the proportional / integral control unit 76 and the excitation end angle command value θoff * is calculated by the adder 72 and input to the inverter control signal generation unit 53. FIG. 6 is a block diagram when both the excitation start angle command value θon * and the excitation end angle command value θoff * are to be adjusted. The difference from FIG. 4 is that the outputs of the proportional / integral control section 96 are two systems, and the difference between the excitation start angle command value θon * and the excitation end angle command value θoff * is calculated by the adders 52 and 72. Is input to the inverter drive signal generation unit 53.
[0031]
In this manner, the excitation start angle command value θon * and the excitation end angle command value θoff * or both are adjusted based on the difference between the output torque estimated value Te and the torque command value T *, so that the operation is performed due to a rise in the temperature of the motor or the like. Even if the winding resistance changes during the process, a desired current waveform can be output.
[0032]
Further, the frequency of sampling the output of the current sensor in one cycle of the electrical angle may be reduced, and a plurality of cycles may be required to complete the contour of the current waveform. However, until the contour of the current waveform is completed, there are conditions such as that the rotor angular velocity, the inverter input voltage, and the torque command value are each constant, and that the current sampling timing is set according to the rotor angle. This can be realized by combining the processes described in the third embodiment to the fourth embodiment with the first embodiment. If the frequency of current sampling can be reduced, an inexpensive sampling device having a slow response time can be used without any problem.
[0033]
Next, a second embodiment will be described with reference to FIGS.
[0034]
7 is a time chart showing the adjustment of the inverter input voltage command value Vin *, FIG. 8 is a flowchart showing the adjustment of the inverter input voltage command value Vin *, and FIG. 9 is a block diagram showing the adjustment of the inverter input voltage command value Vin *. is there.
[0035]
In the second embodiment, the value of the current flowing through the winding of the electric motor at a constant cycle is obtained by the current sensor, and the output of the current sensor is sampled a plurality of times during one cycle of the electrical angle. By storing the rotor angle for one cycle of the electrical angle, a contour of the current waveform for one cycle of the electrical angle is created, and the output torque estimated value Te for one cycle of the electrical angle calculated from the contour and the torque command value T * are calculated. It is characterized by comparing and adjusting the next inverter input voltage command value Vin *.
[0036]
First, the outline of the second embodiment is shown in FIG. FIG. 7 shows an interrupt process 10 for sampling the rotor angle, U-phase winding current, and current sensor output of the SR motor, an interrupt process 110 for calculating the output torque estimated value Te, a torque command value T *, and an output torque estimated value Te. , The change over time of the inverter input voltage command value Vin *.
[0037]
First, an interrupt process for sampling the output of the current sensor is executed at regular intervals to obtain a sampling value. The sampling value and the rotor angle at the time of sampling are stored in a storage device such as a RAM. Subsequently, in an interrupt process 110 executed once per one cycle of the rotor electrical angle, the sampling value for one cycle of the electrical angle and the rotor angle at the time of sampling are read, and the output torque estimated value Te for one cycle of the electrical angle is calculated. I do. Subsequently, based on the difference between the torque command value T * and the output torque estimated value Te, the inverter input voltage command value Vin * in the next electrical angle cycle is determined.
[0038]
Next, details of the second embodiment will be described with reference to the flowchart of FIG.
[0039]
In FIG. 8, steps 110 to 118 are exactly the same as those in FIG. 3 of the first embodiment, so steps 117 and 118 will be described with reference to FIG.
[0040]
First, in the m-th cycle of the electrical angle, one cycle of the electrical angle calculated in the process 34 of FIG. 8 (the estimated torque value generator 55 of FIG. 9) from the torque command value T * output from the torque command value generator 135. The value obtained by subtracting the output torque estimated value Te is input to the proportional / integral control unit 136, and the compensation value Vcomp of the inverter input voltage is obtained. The sampling value Vins of the inverter input voltage Vin is stored, and Vcomp is added to the output value Vm _-1 of the voltage value storage unit 137 that outputs the inverter input voltage in the (m-1) th cycle. The value is Vin _{m + 1} *.
[0041]
In general, in one-pulse control, a method is used in which the excitation start angle command value θon * and the excitation end angle command value θoff * are determined using a map using the rotor angular velocity, the inverter input voltage, and the torque command value as parameters. In this embodiment, the inverter input voltage Vin is further adjusted to obtain a more accurate torque output. Further, although a DC voltage converter such as a DC-DC converter is required, the input voltage of the inverter can be suppressed to the minimum necessary, so that the switching loss of the inverter element can be reduced.
[0042]
Next, a third embodiment will be described with reference to FIG.
[0043]
FIG. 10 is a flowchart for adjusting the excitation start angle θon * when the change in the rotor angular velocity of the motor is equal to or less than a predetermined value.
[0044]
The third embodiment is used in combination with the first embodiment or the second embodiment, and detects that changes in the rotor angular velocity, the inverter input voltage, and the torque command value are equal to or less than predetermined values. Then, the output torque estimation value Te is obtained, and the excitation start angle θon * is adjusted.
[0045]
Next, a method for detecting that the change in the rotor angular velocity of the electric motor is equal to or less than a predetermined value will be described.
[0046]
FIG. 10 shows a flowchart of the output torque estimated value Te calculating process. This flowchart is obtained by adding processing 150 indicated by a broken line to FIG. 3 of the first embodiment.
[0047]
In processing 150, the absolute value | a | of the acceleration of the rotor during one cycle of the electrical angle during the sampling of the current sensor output is obtained, and the output is obtained only when | a | is equal to or _smaller than a predetermined allowable acceleration _amax. The calculation of the torque estimated value Te and the adjustment of the excitation angle command value (processes 31 to 38) are executed.
[0048]
The value of the acceleration a is obtained by the following procedure.
[0049]
Rotor angle of n during the sampling of the U-phase current _{(θu 1, θu 2, ...} , θu n-1, θu n) velocity (n-1) between a position adjacent each of _(vu 1, vu _2, ... , Vun _-2 , vun _-1 ).
[0050]
vu ₁ = (θu ₂ −θu ₁ ) / t
vu ₂ = (θu ₃ −θu ₂ ) / t
…
_{vu n-1 = (θu n} -θu n-1) / t (5)
(T: sampling period)
Furthermore, n-2 pieces from the value of these rates _{(au 1, au 2, ...} , au n-3, au n-2) obtaining the acceleration.
[0051]
au ₁ = (vu ₂ −vu ₁ ) / t
au ₂ = (vu ₃ −vu ₂ ) / t
…
au _n−1 = (vun ₋₁₋ vun ₋₂ ) / t (6)
The maximum value of the absolute value of these n-2 accelerations is defined as acceleration | a |.
[0052]
Note that the method of obtaining a is not limited to this method. Although the rotor position at the time of sampling the U-phase current is used in the third embodiment, the rotor position of the V-phase or W-phase may be used. Although the maximum absolute value of the calculated n-2 accelerations is | a |, the absolute value of the average of the n-2 accelerations may be | a |.
[0053]
Similar processing can be performed not only for the rotor angular velocity but also for the inverter input voltage and the torque command value. As described above, the output torque estimated value Te is obtained based on the contour of the current waveform obtained from the sampling value of the current sensor output in the steady state of the rotor angular velocity, the inverter input voltage, and the torque command value. Can be calculated.
[0054]
A fourth embodiment will be described with reference to FIGS.
[0055]
FIG. 11 is a time chart for creating a contour of a current waveform from a plurality of cycles of an electrical angle, and FIG. 12 is a flowchart for sampling a current of a plurality of cycles of an electrical angle.
[0056]
The fourth embodiment is used in combination with the first embodiment or the second embodiment. The fourth embodiment uses the sampling value of the current sensor output for a plurality of cycles of the electrical angle and the electrical angle based on the rotor angle at this time. It is characterized in that a contour of a current waveform for one cycle of an angle is created.
[0057]
First, an outline of the fourth embodiment will be described with reference to FIG. FIG. 11 shows an interrupt process 190 for sampling the rotor angle of the SR motor, the U-phase winding current, and the output of the current sensor, an outline of the current waveform, an interrupt process 210 for calculating the output torque estimated value Te, and an outline process of the current waveform. It represents the time change.
[0058]
First, the interrupt processing 190 is executed when the rotor reaches a predetermined angle, samples the current sensor output, and stores the sampling value and the rotor angle at the time of sampling in a storage device such as a RAM.
[0059]
Subsequently, in an interrupt process 210 executed once per rotor electrical angle cycle, the sampling value for one electrical angle cycle and the rotor angle at the time of sampling are read, and the output torque estimated value Te for one electrical angle cycle is calculated. I do. Subsequently, based on the difference between the torque command value T * and the output torque estimated value Te, the excitation start angle command value θon * in the next electrical angle cycle is determined.
[0060]
Next, details of the fourth embodiment will be described with reference to FIG.
[0061]
The flowchart in FIG. 12 illustrates a process of sampling the output of the current sensor in the interrupt process of the microcomputer constituting the current control device of the electric motor. This interrupt processing 190 is executed in synchronization with the rotor angle. In process 191, samples the U-phase current, and stores the current value iu _n sampled, the rotor angle .theta.u _n the time of sampling in a storage device such as a RAM. In the processes 192 and 193, the same process as the process 191 is performed for the V phase and the W phase. In the processing 194 199, rotor angle .theta.u _{n + 1} for the next execution of the current sampling, .theta.v _{n + 1,} to determine the .theta.w _{n + 1.} The determination method is obtained from the following equation.
_{θu n + 1 = θu 1 +} (n + 1) α
θv _{n + 1} = θv ₁ + (n + 1) α
θw _{n + 1} = θw ₁ + (n + 1) α
(Α: Minimum unit of angle that position sensor can detect)
Also, an upper limit value p such as 10, for example, is provided for n, and the current sampling angles in the next cycle reaching the upper limit are reset to θu ₁ , θv ₁ , and θw ₁ .
[0062]
As described above, by shifting the rotor angle for sampling the current sensor output for each electrical angle cycle, a contour of the current for one electrical angle cycle can be created from the sampled values for a plurality of cycles.
[0063]
Next, in the interrupt processing 210 of FIG. 11, the output torque estimation value Te is calculated using the sampling value for one cycle of the electrical angle obtained by sampling in the interrupt processing 190 and comparing with the torque command value T *. , The excitation start angle command value θon * and the like are changed. The details of the interrupt process 210 are the same as the interrupt process 30 of the first embodiment and the interrupt process 110 of the second embodiment.
[0064]
By creating a current contour for one electrical angle cycle from the sampled values of the plurality of cycles, it is possible to calculate the output torque estimated value Te even during high-speed rotation where the number of samplings per electrical angle cycle is small. The first embodiment and the second embodiment can be applied at any rotational speed.
[Brief description of the drawings]
FIG. 1 is a time chart showing adjustment of an excitation start angle command value according to a first embodiment of the present invention.
FIG. 2 is a flowchart showing sampling according to the first embodiment of the present invention.
FIG. 3 is a flowchart illustrating adjustment of an excitation start angle command value according to the first embodiment of the present invention.
FIG. 4 is a block diagram of a current control device showing an excitation start angle command value adjustment according to the first embodiment of the present invention.
FIG. 5 is a block diagram of a current control device showing an excitation end angle command value adjustment according to the first embodiment of the present invention.
FIG. 6 is a block diagram of a current control device showing adjustment of an excitation start angle command value and an excitation end angle command value according to the first embodiment of the present invention.
FIG. 7 is a time chart illustrating adjustment of an inverter input voltage command value according to the second embodiment of the present invention.
FIG. 8 is a flowchart showing adjustment of an inverter input voltage command value according to the second embodiment of the present invention.
FIG. 9 is a block diagram of a current control device showing an inverter input voltage command value adjustment according to a second embodiment of the present invention.
FIG. 10 is a flowchart illustrating adjustment of an excitation start angle command value according to a third embodiment of the present invention.
FIG. 11 is a flowchart illustrating the contour formation of a current waveform according to the fourth embodiment of the present invention.
FIG. 12 is a flowchart illustrating sampling according to the fourth embodiment of the present invention.

Claims (8)

An angular position sensor that detects a relative angular position between a stator on which a winding having a plurality of phases is applied and a rotor that is relatively rotated with the stator,
A current sensor for detecting a current of the winding;
In a current detection device for a motor having
A current detection device for an electric motor, comprising current waveform contour creation means for creating a contour of a current waveform from a rotor angle obtained by the angle position sensor and a sampling value of an output of the current sensor. A stator provided with a winding having a plurality of phases, an angular position sensor for detecting a relative angular position between the stator and a rotor rotated relative to the stator, and a current sensor for detecting a current of the winding. It has a current detection device, generates a control signal of an inverter based on a rotor angle obtained from the angular position sensor, applies a rectangular wave voltage to the winding, and switches a phase in which a current flows to operate. In the current control device of the electric motor
A current waveform contour creating unit for creating a contour of a current waveform from the rotor angle and a sampling value of the current sensor output; estimating an output torque value from the contour of the current waveform; A current control device for an electric motor, comprising: a waveform adjusting unit that adjusts a waveform of the rectangular wave voltage according to a difference from a command value. 3. The current control device for an electric motor according to claim 2, wherein the waveform adjusting means adjusts a command value for starting application of the rectangular wave voltage. 3. The current control device for an electric motor according to claim 2, wherein said waveform adjusting means adjusts an application end timing command value of said rectangular wave voltage. 3. The current control device for an electric motor according to claim 2, wherein the waveform adjusting means adjusts an input voltage of the inverter. When detecting that the changes in the rotor angular velocity, the inverter input voltage, and the torque command value during a predetermined period of the motor are equal to or less than a predetermined value, the waveform adjusting unit determines an output torque estimated value from the contour of the current waveform. The current control device for an electric motor according to any one of claims 2 to 5, wherein 2. The current detection device for an electric motor according to claim 1, wherein said current waveform contour creation means samples a current sensor output at a predetermined angle in one cycle of an electrical angle of said rotor. The current waveform contour creating means stores a sampling value of a current sensor output for a plurality of cycles of the electrical angle and a rotor angle at the time of sampling, and calculates a current waveform for one cycle of the electrical angle from the stored sampling value and the rotor angle. The electric current detection device for an electric motor according to claim 1, wherein the contour is created.

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