JP3728405B2 - Control device for synchronous motor - Google Patents

Description

で表される２つの折れ曲がり点を含む折れ線によって近似されるように、予め定めたφ０、Ｎ０、Ｎ１、ＫＶ１、ＫＶ２を用い、
但し、θ（ｘ）は、ｘ≧０のとき、θ（ｘ）＝１、ｘ＜０のときθ（ｘ）＝０で定義される階段関数であるものとし、
最大トルクＴ１より小さいトルク指令｜Ｔｃ｜のときの、最大トルク効率曲線を
φ＝Ｇ［ωｍ＋Ｋ１・（Ｔ１−｜Ｔｃ｜）］−Ｋ２・（Ｔ１−｜Ｔｃ｜） （２）
のように平行移動し、（２）式で｜Ｔｃ｜＝Ｔ２としたとき第２の最大トルク効率曲線に一致するように予め定めた係数Ｋ１，Ｋ２を用いて、Ｔ１〜Ｔ２の間の｜Ｔｃ｜に対して、以上のようにして求めた係数を含む折れ線（２）式を用いて、回転速度ωｍと｜Ｔｃ｜に対する起磁力相差角φを決定する。
【００１４】
このようにすると同期電動機の特性の計算結果を観察し、観察結果を利用して最大トルク効率曲線を３本の折れ線で表すことによって最大トルク効率曲線を単純な表現を実現することができる。更に、トルク指令による最大トルク効率曲線の変動を回転速度に関係なく、基準とする最大トルク効率曲線のトルク値とトルク指令からのトルク値との偏差に比例するベクトル量だけ平行移動すると言う簡単な方法で計算することができる。その結果、広い範囲のトルク値と回転速度ωｍで稼働する電動機のトルク効率を最大にすることができる制御装置を提供することができる効果がある。
【００１５】
また本発明は、ｄ軸のインダクタンスＬｄとｑ軸のインダクタスＬｑとを有し、且つ最大トルク効率で最大トルクＴ１を得るために必要な回転速度と起磁力相差角との関係を示す第１の最大トルク効率曲線が、電機子の回転速度が低いときには、電機子の回転速度の関数として一定値を保ち、回転速度が高くなると、起磁力相差角が増大し始め、次第に増大が緩やかになり、最大トルク効率で最大トルクよりも小さい所定のトルクＴ２を得るために必要な回転速度と起磁力相差角との関係を示す第２の最大トルク効率曲線が、回転速度が低いときには、回転速度の関数として最大トルクのときのときよりも低い一定値を保ち、回転速度が高くなると、最大トルクのときよりも高い回転速度で、起磁力相差角が最大トルクのときよりも小さな値に増大し始め、次第に増大が緩やかになるような特性を有し、回転速度をＸ軸にとり且つ位相角をＹ軸にとったときに、第１及び第２の最大トルク効率曲線の一方をＸ軸方向とＹ軸方向とに平行移動すると他方にほぼ重なる関係が得られる同期電動機をｄ軸電流指令とｑ軸電流指令に従って制御する電力制御手段と、同期電動機の駆動軸の回転速度を検出する回転速度検出手段と、速度指令ωｍｃと回転速度検出手段が検出した電動機の回転速度ωｍとの偏差からトルク指令Ｔｃを発生するトルク指令発生手段と、トルク指令に基づいて電流指令Ｉｃを出力する電流指令演算手段と、起磁力相差角φを用いてｄ軸電流指令とｑ軸電流指令を出力するｄｑ軸電流指令発生手段と、起磁力相差角を発生する起磁力相差角発生手段とを具備する同期電動機の制御装置を改良の対象とする。
【００１６】
本発明の同期電動機の制御装置では、起磁力相差角発生手段は、第１と第２の最大トルク効率曲線をそれぞれ測定又はコンピュータシミュレーションで予め決定しておき、トルク指令｜Ｔｃ｜が第１の最大トルクＴ１に等しいとき、第１の最大トルク効率曲線を与える回転速度ωｍと起磁力相差角φの間の関係を、折れ線で近似できるように予め定めた、ωｍが小さいときの一定値を示す初期起磁力相差角φ０、起磁力相差角が急激に増加し始める第１の起磁力相差角変更速度Ｎ０，Ｎ０以上のωｍでの折れ線の勾配を与える第１の速度補償係数ＫＶ１、起磁力相差角が回転速度の関数として緩やかに増加し始める第２の起磁力相差角変更速度Ｎ１、それ以上での折れ線の勾配を与える第２の速度補償係数ＫＶ２を予め定めておき、これを用いて折れ線の方程式を電動機の回転速度ωｍの関数φＴ１として次式
φＴ１＝φ０＋ＫＶ１・（α−Ｎ０）＋ＫＶ２・（β−Ｎ１） （１１）
によって出力し、
ただし、変数α，βは第１と、第２の記憶装置に保存され、
ωm＜Ｎ０のとき、α＝Ｎ０、β＝Ｎ１ （１２）
Ｎ０≦ωm＜Ｎ１のとき、α＝ωm、β＝Ｎ１ （１３）
Ｎ１≦ωmのとき、α＝Ｎ１、β＝ωm （１４）
のようにスイッチするものとし、このようなφＴ１をωｍの関数として出力する速度補償手段と、
｜Ｔｃ｜＜Ｔ１では、｜Ｔｃ｜の変化による最大トルク効率関数の変化を、｜Ｔｃ｜＝Ｔ１のときの折れ線からＴ１−｜Ｔｃ｜に比例する平行移動で表し、この折れ線φが、第２の最大トルク効率曲線｜Ｔｃ｜＝Ｔ２のときに、最大トルク効率曲線に近似的に一致するように、予め求めた、Ｔ１−｜Ｔｃ｜に対する第１と第２の平行移動係数Ｋ１，Ｋ２を用いて、
起磁力相差角φが最初に増加し始める第１の起磁力相差角変更速度Ｎ０とφが緩やかに増加し始める第２の起磁力相差角変更速度Ｎ１に、これらとＴ１−｜Ｔｃ｜に第１の平行移動係数K１倍した積との加算点で
Ｎ０′＝Ｎ０＋Ｋ１・（Ｔ１−｜Ｔｃ｜） （１５）
Ｎ１′＝Ｎ１＋Ｋ１・（Ｔ１−｜Ｔｃ｜） （１６）
のように加算し、それぞれの和Ｎ０′、Ｎ１′を速度補償手段に入力し、折れ線の式（１１）と折れ線の直線部分を与えるωｍの不等式（１２）、（１３）、（１４）に含まれるＮ０、Ｎ１をＮ０′、Ｎ１′に置き換えて、前記（１１）式の折れ線を右方向に平行移動し、平行移動した折れ線をφｖとし、
この平行移動したφｖと、差分T１−｜Ｔｃ｜を平行移動係数K2倍した積との第３の加算点で次式
φ＝φｖ−Ｋ２・（T１−｜Ｔｃ｜） （１７）
のように減算して、折れ線を下方向への平行移動するトルク補償手段と、
速度補償手段の出力、起磁力相差角φを予め定めた角度以下に抑えるリミッタを有する。
【００１７】
また、速度補償手段は、第１と、第２の記憶装置に保存される変数α、βは、｜Ｔｃ｜＝Ｔ１のときには
ωm＜Ｎ０のとき、α＝Ｎ０、β＝Ｎ１
Ｎ０≦ωm＜Ｎ１のとき、α＝ωm、β＝Ｎ１
Ｎ１≦ωmのとき、α＝Ｎ１、β＝ωm
のようにスイッチするものとし、２つの記憶回路の出力α，βに、それぞれ第１、２の加算点で、トルク指令補償された回転速度Ｎ０，Ｎ１を差し引き、それぞれの差にＫＶ１，ＫＶ２を掛けて、それらの積を第３の加算点で加算し、その和に第４の加算点でφ０を加算した和を速度補償された起磁力相差角として出力し、
｜Ｔｃ｜＜Ｔ１のときには、
ωm＜Ｎ０′のとき、α＝Ｎ０′、β＝Ｎ１′ （１８）
Ｎ０′≦ωm＜Ｎ１′のとき、α＝ωm、β＝Ｎ１′ （１９）
Ｎ１′≦ωmのとき、α＝Ｎ１′、β＝ωm （２０）
のようにスイッチするものとし、２つの記憶回路の出力α，βに、それぞれ第１、２の加算点で、トルク指令補償された回転速度Ｎ０′，Ｎ１′を差し引き、それぞれの差にＫＶ１，ＫＶ２を掛けて、それらの積を第３の加算点で加算し、その和に第４の加算点でφ０を加算した和を速度補償された起磁力相差角として出力するようにしてもよい。
【００１８】
本発明の同期電動機の制御装置では、トルク指令｜Ｔｃ｜が最大トルクＴ１〜０トルクＴ０の値をとるとき、係数調整手段は、｜Ｔｃ｜＝Ｔ１，Ｔ２，Ｔ０のときの最大トルク効率曲線を求めておき、Ｔ１をこれらのいずれかに等しいトルク値とし、｜Ｔｃ｜＝Ｔ１のときの最大トルク効率曲線を２つの折れ曲がり点を持つ折れ線で近似できるように、速度座標Ｎ０，Ｎ１，初期起磁力相差角φ０，速度補償係数ＫＶ１，ＫＶ２を調整しておき、｜Ｔｃ｜≠Ｔ１のとき、ＴＰ−｜Ｔｃ｜の代わりに、Ｔ１−｜Ｔｃ｜を用いてトルク補償を行った折れ線で、Ｔ２≠Ｔ１でＴＰ，ＴＲ，Ｔ０のどれかに等しいＴ２を用いて、｜Ｔｃ｜＝Ｔ２とおいたときのトルク補償した折れ線が、このときの最大トルク効率曲線と近似的に一致するようにＫ１，Ｋ２を定めて、起磁力相差角発生手段は、｜Ｔｃ｜がＴ１〜Ｔ２の間の値におけるトルク補償した折れ線で、ωｍと｜Ｔｃ｜対φの折れ線の関係を用いてトルク補償を行うようにしてもよい。
【００１９】
【発明の実施の形態】
以下、図面を参照して本発明の実施の形態の一例を詳細に説明する。図１は、本発明を同期電動機１の制御装置に適用した実施の形態の一例の回路図である。同期電動機１は複数の永久磁石がロータコアに埋め込まれているロータを備え、永久磁石の直軸であるｄ軸のインダクタンスＬｄとこの直軸と電気角で直交する直交軸であるｑ軸のインダクタンスＬｑとの関係がＬｄ＜Ｌｑとなる埋込磁石形同期電動機（以下、「ＩＰＭ電動機」という）である。なお本発明はロータコアの表面に永久磁石を固定するタイプの同期電動機等にも当然にして適用できる。起磁力相差角φは、ｄ軸と１次電流指令Ｉｃとのなす角である。
【００２０】
図１において、トルク指令発生手段３は、速度指令ωmcと回転速度検出手段５で検出された同期電動機１の回転速度ωmとの偏差からトルク指令Tcを算出する。電流指令演算手段６は、トルク指令発生手段３からのトルク指令に基づいて電流指令Ｉｃを出力する。ｄｑ軸電流指令発生手段７は、電流指令とｄ軸との間の角度として定義される起磁力相差角φを用いて、ｄ軸電流指令とｑ軸電流指令を出力しする。起磁力相差角発生手段９は起磁力相差角φを発生し、ｄｑ軸電流指令発生手段７に出力する。電力制御手段１１はこのｄ軸電流指令とｑ軸電流指令に従って同期電動機１を駆動する。
【００２１】
トルク指令発生手段３は、速度制御器３ａと加算点３ｂとにより構成されている。速度制御器３ａは、速度指令信号ωmcと回転速度検出手段５で検出した同期電動機の回転速度ωmとの速度偏差を加算点３ｂで求め、その速度偏差からトルク指令Ｔｃを演算する。回転速度検出手段５は、エンコーダ５ａと速度検出器５ｂとで構成される。速度検出器５ｂは、エンコーダ５ａで検出した回転位置θmから回転速度ωmを検出する。電流指令演算手段６は電流指令演算器（ＫＴＩ）６ａとリミッタ６ｂから構成される。電流指令演算器６ａは、トルク指令Ｔｃに電流指令換算係数ＫＴＩを乗算して電流指令Ｉｃを演算する。リミッタ６ｂは電流指令Ｉｃを一定値にリミットする。ｄｑ軸電流指令発生手段７は、絶対値化器７ａと、ｓｉｎφ信号発生器７ｂと、ｃｏｓφ信号発生器７ｃとから構成される。ｓｉｎφ信号発生器７ｂは、リミット処理後の電流指令Ｉｃをｓｉｎφ倍して、ｑ軸電流指令Ｉｑｃを算出する。ｃｏｓ信号発生器７ｃは、リミット処理後の電流指令Ｉｃを絶対値化器７ａで絶対値化し、それをｃｏｓφ倍して、d軸電流指令Ｉｄｃを算出する。以上のようにして算出されたｑ軸電流指令Ｉｑｃ及びｄ軸電流指令Ｉｄｃを電力制御部１１に送る。
【００２２】
電力制御部１１は、２つの積分制御器１１ａ及び１１ｂ，信号発生器１１ｃ，，第１及び第２の座標変換器１１ｄ及び１１ｅ，電流制御器１１ｆ，ＰＷＭ制御器１１ｇ，電力変換器１１ｈ，電流検出手段１１ｉから構成される。
【００２３】
信号発生手段１１ｃは、エンコーダ５ａにより検出した回転位置θｍｆに基づいて、第１の座標変換器１１ｄと、第２の座標変換器１１ｅに対して設けられたｓｉｎθmf信号とｃｏｓθmf信号を発生する。
【００２４】
第１の座標変換器１１ｄは、電流検出手段１１ｉにより検出した出力電流と信号発生手段１１ｃから出力されるｓｉｎθmf信号及びｃｏｓθmf信号とを入力信号としてｄ軸電流フィードバック信号Ｉｄｆ及びｑ軸電流フィードバック信号Iｑｆを出力する。
【００２５】
第２の座標変換器１１ｅは、ｑ軸電流指令Ｉｑｃとｑ軸電フィードバックＩｑｆとの差をとり、この差を積分制御器１１ａを通してｑ軸電流指令Ｉｑｃと加算点１１ａで加算し、積分補償量を含んだｑ軸電流指令Ｉｑｃ′を求める。同様にIｄｃ′も求める。Ｉｑｃ′とＩｑｃ′を第２の座標変換器１１ｅを通して、３相の電流指令ＩＵｃ，ＩＶｃ，ＩＷｃを求める。電流制御器１１ｆにおいて、電流フイードバックとの偏差をとり、比例演算して電圧指令ＶＵｃ，ＶＶｃ，ＶＷｃを得る。これをＰＷＭ制御器１１ｇに通し、電力変換器１１ｈによりＩＰＭ電動機１を駆動する。
【００２６】
起磁力相差角発生手段９は、最大トルクを発生する際に、最大トルク効率を得るのに必要な回転速度ωｍと起磁力相差角φとの関係を示す第１のデータ曲線と最大トルクよりも小さな所定のトルクを発生する際に最大トルク効率を得るのに必要な回転速度と起磁力相差角との関係を示す第２のデータ曲線に基づいて所定の回転速度において、最大トルクと所定のトルク間のトルクを最大トルク効率で発生させるのに必要な起磁力相差角φを決定するように構成されている。
【００２７】
図２は、この実施例が制御の対象とするＩＰＭ電動機の場合の定格トルク、及び、最大トルクのときの、トルク効率が最大となる起磁力相差角をシミュレーションにより求めたものである。トルク効率が最大となる起磁力相差角は、最大トルク時と、定格トルク時とでは異なり、定格トルク時は、最大トルクのときより、小さな起磁力相差角で、トルク効率が最大となる。定格トルクの曲線では電機子の回転速度が低いときには、電機子の回転速度の関数として一定値を保ち、回転速度が高くなると、起磁力相差角が増大し始め、次第に増大が緩やかになっている。ＩＰＭ電動機で磁気飽和が無い場合は、ＩＰＭ電動機のトルクはリラタタンストルクとマグネットトルクの和として得られるので、起磁力相差角１２０〜１３５°付近でトルク効率が最大となる。定格トルクで、回転速度が低い場合の起磁力相差角は、これに相当する。回転速度が高くなった場合は、電動機電圧が上昇してくるため、電力変換器の出力電圧を超えないよう、起磁力相差角が回転速度の上昇と共に大きくなる。最大トルクの曲線では、回転速度が低いときには、回転速度の関数として定格トルクのときよりも高い一定値を保ち、回転速度が高くなると、定格トルクのときよりも低い回転速度で、起磁力相差角が最大トルクのときよりも大きな値に増大し始め、次第に増大が緩やかになるような特性を有している。最大トルク時は、起磁力相差角を若干大きくして、磁気飽和を緩和した所が最大トルク効率となる。また、定格トルクのときより電動機電圧が高くなるため、定格トルクのときより低い回転速度から起磁力相差角を大きくする必要がある。従って最大トルクと定格トルクのときの最大トルク効率曲線の一方を横軸方向と縦軸方向とに平行移動すると他方にほぼ重なる関係になっている。本発明ではこのような同期電動機の特性を利用して、それを有効に制御する制御装置を提供する。
【００２８】
図３は、図１に示す第１の実施の形態の動作を説明するためのグラフである。縦軸に起磁力相差角φ、横軸に回転速度ωｍを示す。図３で、３本の折れ線はそれぞれ｜Ｔｃ｜が、最大トルク（TP）、定格トルク（TR）、トルク0（TO）のときの、図２に示すような実験またはシミュレーションで得られた最大トルク効率曲線を近似する折れ線を示したものである。
【００２９】
図１に示すように、起磁力相差角発生手段９は、速度補償手段１３と第１，２のトルク補償手段１５とリミッタ１７とから構成される。速度補償手段１３は、トルク指令｜Ｔｃ｜が第１の最大トルクＴ１に等しいとき、第１の最大トルク効率曲線を与える回転速度ωｍと起磁力相差角φの間の関係を、折れ線で近似できるように予め定めておく。折れ線を決める定数としては、ωｍが小さいときの一定値である初期起磁力相差角φ０、起磁力相差角が急激に増加し始める第１の起磁力相差角変更速度Ｎ０、第１の起磁力相差角変更速度Ｎ０以上のωｍでの折れ線の勾配を与える速度補償係数ＫＶ１、起磁力相差角が回転速度の関数として緩やかに増加し始める第２の起磁力相差角変更速度Ｎ１、それ以上での折れ線の勾配を与える速度補償係数ＫＶ２を用いる。速度補償手段１３は、これらの定数を用いて、折れ線の方程式を電動機の回転速度ωｍの関数φＴ１として次式
φＴ１＝φ０＋ＫＶ１・（α−Ｎ０）＋ＫＶ２・（β−Ｎ１） （２１）
によって出力する。
【００３０】
但し、
ωm＜Ｎ０のとき、α＝Ｎ０、β＝Ｎ１ （２２）
Ｎ０≦ωm＜Ｎ１のとき、α＝ωm、β＝Ｎ１ （２３）
Ｎ１≦ωmのとき、α＝Ｎ１、β＝ωm （２４）
のように変更するものとする。
【００３１】
このようにして得られた起磁力相差角φＴ１は、ωｍの関数として図３に示す｜Ｔｃ｜＝Ｔ１＝ＴＰの折れ線のグラフになる。
【００３２】
ωmが０〜Ｎ０までの範囲では、式（１）で、ωm＜Ｎ０のときの、α＝Ｎ０、β＝Ｎ１を代入すると、右辺の第１項のみが残る。従って、
φＴ１＝φ０ （２５）
のような一定値になる。
【００３３】
ωｍがＮ０〜Ｎ１では、（１）式で、Ｎ０≦ωm＜Ｎ１のときの、α＝ωm、β＝Ｎ１を代入すると、
φＴ１＝φ０＋ＫＶ１・（ωｍ−Ｎ０） （２６）
のように第２項が加算され、ωｍ＝Ｎ０で折れ曲がる勾配を与える速度補償係数ＫＶ１の折れ線になる。
【００３４】
ωｍがＮ１以上のときは、Ｎ１≦ωmのときの、α＝Ｎ１、β＝ωmを代入すると、
φＴ１＝φ０＋ＫＶ１・（Ｎ１−Ｎ０）＋ＫＶ２・（ωｍ−Ｎ１） （２７）
のように第３項が加算されて、ωｍ＝Ｎ１で折れ曲がる勾配を与える速度補償係数ＫＶ２の折れ線ができる。
【００３５】
図４に、図１の実施の形態で示した速度補償手段１３の構成の一例を示す。この速度補償手段１３は、記憶装置１３ａ，１３ｂ、速度補償係数演算器１３ｃ，１３ｄ、加算点１３ｅ，１３ｆ，１３ｇ，１３ｈで構成されている。速度補償手段１３に起磁力相差角変更速度Ｎ０，Ｎ１、初期起磁力相差角φ０、速度補償係数ＫＶ１，ＫＶ２、をパラメータとして入力し、ωｍを入力変数とする。第１及び第２の記憶装置１３ａ及び１３ｂに保存される変数α，βは、｜Ｔｃ｜＝Ｔ１のときには
ωm＜Ｎ０のとき、α＝Ｎ０、β＝Ｎ１ （２８）
Ｎ０≦ωm＜Ｎ１のとき、α＝ωm、β＝Ｎ１ （２９）
Ｎ１≦ωmのとき、α＝Ｎ１、β＝ωm （３０）
のように変更する。内部の２つの記憶回路１３ａ及び１３ｂからの出力α，βに、それぞれ加算点１３ｅ及び１３ｆで、トルク指令補償された起磁力相差角変更速度Ｎ０，Ｎ１を差し引き、それぞれの差に速度補償係数演算器１３ｃ，１３ｄで速度補償係数ＫＶ１，ＫＶ２を掛けて、それらの積を加算点１３ｇで加算し、その和に加算点１３ｈでφ０を加算した和を速度補償された起磁力相差角φＴ１として出力する。
【００３６】
｜Ｔｃ｜＜Ｔ１では、トルク補償手段１５が作動する。トルク補償手段１５は、第１の平行移動係数演算器１５ａ、第２の平行移動係数演算器１５ｄ、加算点１５ｂ，１５ｃ，１５ｅから構成されている。平行移動係数演算器１５ａは、トルク指令｜Ｔｃ｜＝Ｔ１における折れ線をＴ１−｜Ｔｃ｜に比例して、右方向にＫ１・（Ｔ１−｜Ｔｃ｜）平行移動し、第２の平行移動係数演算器１５ｄは下降方向にＫ２・（Ｔ１−｜Ｔｃ｜）平行移動する。このとき、平行移動係数Ｋ１及びＫ２は、図３に示すように、｜Ｔｃ｜＝Ｔ２＝ＴＲのときの折れ線が、｜Ｔｃ｜＝Ｔ２のときの最大トルク効率曲線に近似的に一致するように予め決めておく。第１及び第２のトルク補償手段は予めこのようにしてそれぞれ決まった速度補償係数Ｋ１、Ｋ２を用いて横方向平行移動と下降方向平行移動を以下のように行う。
【００３７】
図１において、トルク補償手段１５は、第１の平行移動係数演算器１５ａによって、トルク入力の偏差（Ｔ１−｜Ｔｃ｜）と平行移動係数Ｋ１との積Ｋ１・（Ｔ１−｜Ｔｃ｜）を生成し、この積と折れ曲がり点の横座標である起磁力相差角変更速度Ｎ０，Ｎ１とを加算点１５ｂ，１５ｃで次式
Ｎ０′＝Ｎ０＋Ｋ１・（Ｔ１−｜Ｔｃ｜） （３１）
Ｎ１′＝Ｎ１＋Ｋ１・（Ｔ１−｜Ｔｃ｜） （３２）
のような加算を行い、トルク補償した起磁力相差角変更速度Ｎ０′及びＮ１′を演算し、これらを速度補償手段１３に入力する。
【００３８】
速度補償手段１３は、（２１）式のφＴ１に含まれる起磁力相差角変更速度Ｎ０，Ｎ１を次式
φｖ＝φ0＋ＫＶ１・（α−Ｎ０′）＋ＫＶ２・（β−Ｎ１′） （３３）
のようにＮ０′，Ｎ１′に置き換えた折れ線の起磁力相差角φｖを出力する。φｖはωｍの関数として｜Ｔｃ｜＝Ｔ１＝ＴＰの折れ線を速度軸に右方向に平行移動した折れ線になっている。
【００３９】
ただし、第１と、第２の記憶装置１３ａ及び１３ｂの記憶内容α，βは、
ωm＜Ｎ０′のとき、α＝Ｎ０′，β＝Ｎ１′ （３４）
Ｎ０′≦ωm＜Ｎ１′のとき、α＝ωm，β＝Ｎ１′ （３５）
Ｎ１′≦ωmのとき、α＝Ｎ１′，β＝ωm （３６）
のように折れ曲がり点で変更して横座標も平行移動したものになっている。
【００４０】
図４において、｜Ｔｃ｜＜Ｔ１で、速度補償手段１３に起磁力相差角変更速度Ｎ０′，Ｎ１′、初期起磁力相差角φ０、速度補償係数ＫＶ１，ＫＶ２をパラメータとして入力し、ωｍを入力変数とする。第１及び第２の記憶装置１３ａ，１３ｂに保存される変数α，βは、上記式（３４）乃至（３６）のように変更される。
【００４１】
２つの記憶回路１３ａ及び１３ｂからの出力α，βに、それぞれ加算点１３ｅ，１３ｆで、トルク指令補償された起磁力相差角変更速度Ｎ０′，Ｎ１′を差し引き、それぞれの差に速度補償係数ＫＶ１，ＫＶ２を掛けて、それらの積を加算点１３ｇで加算し、その和に加算点１３ｈでφ０を加算した（３３）式の和φｖを出力する。
【００４２】
またトルク補償手段１５は、速度補償手段１３の出力の起磁力相差角φｖと、差分Ｔ１−｜Ｔｃ｜を第２の平行移動係数演算器１５ｄで平行移動係数Ｋ２倍した積とを加算点１５ｅで次式
φ＝φｖ−Ｋ２・（Ｔ１−｜Ｔｃ｜） （３７）
のように差し引き、（３３）式の折れ線φｖを縦方向に平行移動し、（３７）式の起磁力相差角φを｜Ｔｃ｜＜Ｔ１における回転速度ωｍに対する起磁力相差角φとして出力する。
【００４３】
リミッタ１７は速度補償手段１３の出力である起磁力相差角φを予め定めた角度以下に抑える。リミッタ１７は、φを９０〜１８０°以内にリミット処理し、各種補償後の起磁力相差角φとする。
【００４４】
図３でトルク指令｜Ｔｃ｜が定格トルクＴＲ以下でＴ０以上のとき、即ちＴ０＜Ｔｃ＜ＴＲのときには、Ｔ１＝ＴＲ、Ｔ２＝Ｔ０とおいて以上述べたのと同じ関係を使うことができる。またはＴ１＝Ｔ０、Ｔ２＝ＴＲとおいて、以上の関係でＴ１−｜Ｔｃ｜の替わりに｜Ｔｃ｜を用いてトルク補償と、速度補償を行うこともできる。
【００４５】
図３を用いて本発明の第２の実施の形態の１例を説明する。本実施の形態では、起磁力相差角発生手段９は、図１の実施の形態に示す同期電動機を制御するための起磁力相差角φを以下のようにして発生する。
【００４６】
ステップＳ１：起磁力相差角発生手段９は、図２に示すような第１と第２の最大トルク効率曲線を測定又はコンピュータシミュレーションで予め決定しておく。第１と第２のトルク指令｜Ｔｃ｜は、例えば最大トルクＴＰ、定格トルクＴＲ、０トルクＴ０のいずれかの異なる２つのトルク指令の組として選ぶことができる。
【００４７】
ステップＳ２：｜Ｔｃ｜＝Ｔ１のときの最大トルク効率関数関係を次式のように２つの折れ曲がり点を含む折れ線で近似する。
【００４８】

但し、ステップ関数θ（ｘ）は、ｘ≧０のとき、θ（ｘ）＝１、ｘ＜０のときθ（ｘ）＝０で定義される。ここでωｍが０〜Ｎ０の間は、φは第１項のみの一定値φ０になる。ωｍがＮ０〜Ｎ１の間は、第２項が加算されて、勾配ＫＶ１の折れ線になる。ωｍがＮ１以上では、第２項は一定値になり、第３項が加算されて、勾配ＫＶ２の折れ線になる。この折れ線が最大トルク効率関数関係の良い近似で表されるように、φ０，Ｎ０，Ｎ１，ＫＶ１，ＫＶ２を予め決定しておく。
【００４９】
ステップＳ３：Ｔ１と異なる｜Ｔｃ｜のときの、最大トルク効率曲線を
φ＝Ｇ［ωｍ−Ｋ１・（Ｔ１−｜Ｔｃ｜）］−Ｋ２・（Ｔ１−｜Ｔｃ｜） （３９）
のように平行移動した折れ線で近似する。ここで平行移動した折れ線が｜Ｔｃ｜＝Ｔ２のときの最大トルク効率曲線に一致するように平行移動係数Ｋ１，Ｋ２を決定する。
【００５０】
ステップＳ４：Ｔ１〜Ｔ２の間の｜Ｔｃ｜に対して、以上のようにして定数を決定した折れ線（３９）式を用いて、回転速度ωｍと｜Ｔｃ｜に対する起磁力相差角φを決定する。
【００５１】
図５は本発明の第３の実施の形態を説明するために用いる図である。この実施の形態では、図１の実施の形態に示す起磁力相差角発生手段９は起磁力相差角φを以下のように発生する。
【００５２】
ステップＳ１：起磁力相差角発生手段９は、第１と第２の最大トルク効率曲線を測定又はコンピュータシミュレーションで予め決定しておく。第１と第２のトルク指令｜Ｔｃ｜は、最大トルクＴＰ、定格トルクＴＲ、０トルクＴ０のいずれかの異なる２つのトルク指令の組に選ぶことができる。
【００５３】
ステップＳ２：｜Ｔｃ｜＝Ｔ１のときの最大トルク効率曲線を、次式
φ＝Ｆ（ωｍ） （４０）
とする。Ｆ（ωｍ）の式の形としては、例えは数値計算の結果を簡単な多項式で近似したものを用いてもよい。例えばＦ（ωｍ）とＮ個の点で一致する多項式を決めるには、Ｎ−１次の多項式を用いればよい。この場合にはＮ個の係数を必要とするので、Ｎ個の点の関数値が決まればＮ個の係数が決まる。このような決め方は折れ線近似よりは近似の精度を高めることができる効果が期待できる。
【００５４】
ステップＳ３：Ｔ１と異なる｜Ｔｃ｜のときの、最大トルク効率曲線を
φ＝Ｆ［ωｍ＋Ｋ１・（Ｔ１−｜Ｔｃ｜）］−Ｋ２・（Ｔ１−｜Ｔｃ｜） （４１）
のように平行移動する。｜Ｔｃ｜＝Ｔ２のときの最大トルク効率曲線に例えば最小自乗法で一致するように平行移動係数Ｋ１，Ｋ２を決定する。
【００５５】
ステップＳ４：Ｔ１〜Ｔ２の間の｜Ｔｃ｜に対して（４１）式を用いて、ωｍからφを決める。
【００５６】
図６は本発明の第４の実施の形態の一例を説明するために用いるグラフである。この実施の形態では、図１の実施の形態に示す起磁力相差角発生手段９は起磁力相差角φを以下のステップに従って出力する。
【００５７】
ステップＳ１：図２に示すようにトルク効率が最大となる電動機の回転速度ωｍと起磁力相差角φとの間の最大トルク効率曲線を、トルク指令が最大トルクＴＰ、定格トルクＴＲ、トルク０時Ｔ０に対して、予め求めておく。以下ではトルク指令Ｔｃが｜Ｔｃ｜＝ＴＰ，ＴＲ，Ｔ０の場合を、それぞれ｜Ｔｃ｜＝Ｔ（ｉ）（ｉ＝０，１，２）と書くことにする。説明の便宜のためにこのようなトルク指令値を例として選ぶが、複数のトルク値に対する最大トルク効率曲線を用いる場合に一般化することができる。本実施の形態で最大トルクＴ（０）は本発明の請求項７において最大トルクＴ１と表記したものに相当する。本実施の形態で定格トルクＴ（１）は本発明の請求項７で、最大トルクよりも小さい所定のトルクＴ２としたものの一例である。本実施の形態の３つのトルクの場合は請求項７の２つのトルクの場合からの一般化になっている。
【００５８】
ステップＳ２：ステップＳ１で求めた３つの最大トルク効率曲線における起磁力相差角φと回転速度ωｍの関数関係を、図６（Ａ）に示すようにそれぞれ同数の複数の折れ曲がり点からなる折れ線で近似し、それぞれの折れ線の折れ曲がり点を同じ順番同志で互いに対応を付ける。例えば、これらに折れ曲がり点に１からＮ−１までの番号をつけ、０を始点、Ｎを終点とする。０からＮまでの始点と終点を含む折れ曲がり点をそれぞれ番号ｊによってｊ＝０〜Ｎとする。横軸をωｍとし縦軸をφとするωｍ−φ平面上の番号ｉの折れ線の番号ｊの折れ曲がり点（ｉ，ｊ）（ｉ＝０〜２、ｊ＝０〜Ｎ）の座標を、Ｎ（ｉ，ｊ）、φ（ｉ，ｊ）とする。ｉ番目の最大トルク効率曲線を近似する折れ線の折れ曲がり点の数は同数のＮ−１個であり、それぞれの折れ線のｊ番目の折れ曲がり点が互いに対応する番号ｊの折れ曲がり点になっている。
【００５９】
ステップＳ３：トルク指令Ｔｃの大きさ｜Ｔｃ｜が２つのトルク値Ｔ（ｉ）、Ｔ（ｉ＋１）の間の値をとるときに、回転速度ωｍに対してトルク効率を最大にする起磁力相差角φを求める。以下ｉ＝０に固定しておく。ｉ＝１に固定した場合も以下の話は同様に成立する。起磁力相差角φを求めるのに必要な最大トルク効率曲線の部分を近似的に求めるためにまず図６（Ｂ）に示すような４辺形を決める。即ち、図６（Ｂ）において、ｉ番目のトルク値Ｔ（ｉ）のときのトルク効率を最大にする最大トルク効率曲線を近似する折れ線の一直線区間、即ち２つの折れ曲がり点（Ｎ（ｉ，ｊ）、φ（ｉ，ｊ））と（Ｎ（ｉ，ｊ＋１）、φ（ｉ，ｊ＋１）を結ぶ線と、ｉ＋１番目のトルク値Ｔ（ｉ＋１）のときのトルク効率を最大にする最大トルク効率曲線を近似する折れ線の一直線区間、即ち２つの折れ曲がり点（Ｎ（ｉ＋１，ｊ）、φ（ｉ＋１，ｊ））と（Ｎ（ｉ＋１，ｊ＋１）、φ（ｉ＋１，ｊ＋１）を結ぶ線を対辺とする４辺形を作る。ここでｊの値としては、Ｎ（ｉ，ｊ）＜ωｍ＜Ｎ（ｉ，ｊ＋１）の関係を満足するように選ぶ。これらの４辺形の頂点はそれぞれの４辺形の対辺の両端の点になっており、またそれぞれｊ、ｊ＋１番目の対応する同じ順番の点になっている。ここでｊは、０〜Ｎ−１の中の１つの数である。
【００６０】
ステップＳ４：ステップＳ３で求めた４辺形を形作る対辺の両端の点の中でｊ番目の点同志（Ｎ（ｉ，ｊ）、φ（ｉ，ｊ））と（Ｎ（ｉ＋１，ｊ）、φ（ｉ＋１，ｊ）をつなぐ第１の辺を、Ｔ（ｉ）−｜Ｔｃ｜：｜Ｔｃ｜−Ｔ（ｉ＋１）の比に内分する第１の内分点（Ｎ（｜Ｔｃ｜，ｊ）、φ（｜Ｔｃ｜，ｊ））を次式によって求める。
【００６１】

ステップＳ５：同様に、ステップＳ３で求めた４辺形を形作る対辺の両端の点の中でｊ＋１番目の点同志（Ｎ（ｉ，ｊ＋１）、φ（ｉ，ｊ＋１））と（Ｎ（ｉ＋１，ｊ＋１）、φ（ｉ＋１，ｊ＋１）をつなぐ第２の辺を、Ｔ（ｉ）１−｜Ｔｃ｜：｜Ｔｃ｜−Ｔ（ｉ＋１）の比に内分する第２の内分点（Ｎ（｜Ｔｃ｜，ｊ＋１）、φ（｜Ｔｃ｜，ｊ＋１））を次式によって求める。
【００６２】

ステップＳ６：回転速度検出手段５から求めた回転速度ωｍが、Ｎ（｜Ｔｃ｜，ｊ）〜Ｎ（｜Ｔｃ｜，ｊ＋１）］をつなぐ線分の範囲内にあることを判定する。そうしてステップＳ３で４辺形を選ぶ時にこのようになるように選ぶ。そうなっていない場合にはステップＳ３に戻り、ωｍ＜Ｎ（ｉ＋１，ｊ）のときは、ｊをｊ＋１にして、ωｍ＞φ（ｉ＋１，ｊ＋１）時はｊをｊ−１にして条件を満たすまでステップＳ３〜ステップＳ６を繰り返す。条件を満足すれば次のステップに進む。
【００６３】
ステップＳ７：ステップＳ６の条件を満足したとき、これらの内分点をつなぐ線分の方程式は次式のようなωｍとφの１次式の関係で与えられる。
【００６４】

これによってωｍからφを決定する。
【００６５】
ステップＳ８：ωｍに対するφを出力する。
【００６６】
図７は、従来方式と、本方式における定格運転ときの電動機コイル温度上昇の実測結果である。これから、本方式は、定格回転速度ときのトルク効率を大幅に改善できていることがわかる。
【００６７】
上記各実施の形態によれば、以下の効果が得られる。
【００６８】
（１）最大トルク領域のみならず、定格トルク領域においても電動機のトルク効率を最大にできるようになったため、高効率で、エネルギー消費の少ない電動機制御装置を提供できる。
【００６９】
（２）電動機をより小型、軽量に設計できるようになる。
【００７０】
（３）トルク０〜最大トルクまでの起磁力相差角を最大トルクとトルク指令の絶対値との差に比例させて制御するようにしたため、少ない電動機パラメータでトルク調整が可能である。また、最大トルク時をベースにしたトルク調整が可能である。
【００７１】
【発明の効果】
本発明のように、トルク指令と回転速度とによって起磁力相差角を制御すると、最大トルク領域のみならず、最大トルクよりも小さな所定のトルク領域においても、電動機のトルク効率が最大となるように制御することができる簡単な構造の同期電動機の制御装置を得ることができる。その結果、本発明によれば、トルク指令や回転速度が広い範囲で変動しても常にトルク効率を最大に保ちながら電動機を稼働させることができる効果が得られる。
【図面の簡単な説明】
【図１】本発明の第１の実施の形態の同期電動機の制御装置の一例の構成を示すブロック図である。
【図２】本発明が制御の対象とする同期電動機の特性のシミュレーション結果である。
【図３】本発明が制御の対象とする同期電動機の特性のシミュレーション結果を折れ線近似したものある。
【図４】本発明の第１の実施の形態の実施の形態の同期電動機の制御装置の一部の詳細を示すブロック図である。
【図５】トルク補償曲線を平行移動近似する方法を説明する図である。
【図６】（Ａ）及び（Ｂ）は折れ線近似と内分点を用いる方法を説明するための図である。
【図７】本発明の効果を説明するための図である。
【図８】同期電動機の従来の制御法を説明するための図である。
【符号の説明】
１ ＩＰＭ電動機
３ トルク指令発生手段
３ａ 速度制御器
３ｂ 加算点
５ 回転速度検出手段
５ａ エンコーダ
５ｂ 速度検出器
６ａ 電流指令演算器
６ｂ リミッタ
７ ｄｑ軸電流指令発生手段
７ａ 絶対値化器
７ｂ ｓｉｎ信号発生器
７ｃ ｃｏｓ信号発生器
９ 起磁力相差角発生手段
１１ 電力制御手段
１１ａ，１１ｂ 積分制御器
１１ｃ 信号発生器
１１ｄ 第１の座標変換器
１１ｅ 第２の座標変換器
１１ｆ 電流制御器
１１ｇ ＰＷＭ制御器
１１ｈ 電力変換器
１１ｉ 電流検出手段
１１ｓ，１１ｔ，１１ｕ，１１ｖ 加算点
１３ 速度補償手段
１３ａ，１３ｂ 記憶回路
１３ｃ ＫＶ１
１３ｄ ＫＶ２
１３ｅ，１３ｆ，１３ｇ，１３ｈ 加算点
１５ トルク補償手段
１５ｂ，１５ｃ，１５ｅ 加算点
１７ リミッタ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device for a synchronous motor having a d-axis inductance Ld and a q-axis inductance Lq.
[0002]
[Prior art]
A typical example of a synchronous motor having a d-axis inductance and a q-axis inductance is an embedded magnet type synchronous motor. In the conventional synchronous motor control device, as shown in FIG. 8, the magnetomotive force phase difference angle φ is constant so that the torque constant at the maximum torque is maximized in the low speed region, and maximum in the high speed region. Φ is increased according to the speed so that the motor voltage at the time of torque is less than or equal to the output voltage of the power converter.
[0003]
[Problems to be solved by the invention]
When the control is performed according to one relationship as in the conventional control device, the torque efficiency can be maximized at the maximum torque, but the torque efficiency cannot always be maximized at the rated torque. In order to solve these problems, it was found that the magnetomotive force phase difference angle at which the torque efficiency is maximized is different between the maximum torque and the rated torque. It has become necessary to refine the control of the synchronous motor in consideration of the characteristics of the synchronous motor. For example, recent motor designs tend to be smaller and lighter, and when the maximum torque is controlled as a reference for the magnetomotive force phase difference angle as in the conventional control method, the temperature rise of the motor during rated operation is standard. The problem of not entering the value arises. In addition, it was necessary to reduce energy consumption from the viewpoint of conservation of the global environment.
[0004]
On the other hand, it is also conceivable to set the magnetomotive force phase difference angle so that the maximum torque efficiency is achieved at the rated torque. However, if it does in this way, the problem that a torque will not be obtained this time will arise.
[0005]
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a motor control device that maximizes the torque efficiency of the motor not only in the maximum torque region but also in the rated torque region. And
[0006]
[Means for Solving the Problems]
The present invention detects electric power control means for controlling a synchronous motor having a d-axis inductance Ld and a q-axis inductance Lq according to a d-axis current command and a q-axis current command, and a rotational speed of a drive shaft of the synchronous motor. Rotation speed detection means, torque command generation means for generating a torque command Tc from the deviation between the speed command ωmc and the rotation speed ωm of the motor detected by the rotation speed detection means, and a current for outputting a current command Ic based on the torque command A command calculation means, a dq-axis current command generation means for outputting a d-axis current command and a q-axis current command using a magnetomotive force phase difference angle φ defined as an angle between the current command and the d-axis, and a magnetomotive force A synchronous motor control device comprising magnetomotive force phase difference angle generating means for generating a phase difference angle is an object of improvement. The torque command generation means may be configured to generate the torque command from a deviation between the speed command ωmc and the rotation speed ωm of the electric motor detected by the rotation speed detection means, but may be configured to generate the torque command independently. The configuration may be arbitrary.
[0007]
In the control apparatus for a synchronous motor according to the present invention, the magnetomotive force phase difference angle generating means generates the maximum torque when the maximum torque efficiency is obtained, and the magnetomotive force phase difference angle φ indicates the relationship between the rotational speed ωm and the magnetomotive force phase difference angle φ. The predetermined rotation based on the first data curve and the second data curve indicating the relationship between the rotational speed and the magnetomotive force phase difference angle required to obtain the maximum torque efficiency when generating a predetermined torque smaller than the maximum torque. A magnetomotive force phase difference angle φ required to generate a torque between a maximum torque and a predetermined torque at a maximum torque efficiency is determined.
[0008]
When the magnetomotive force phase difference angle is controlled by the torque command and the rotational speed as described above, the torque efficiency of the electric motor can be controlled not only in the maximum torque region but also in a predetermined torque region smaller than the maximum torque. A control device for a synchronous motor having a simple structure can be obtained. As a result, there is an effect that the motor can be operated while the torque efficiency is always kept at the maximum even if the torque command and the rotational speed fluctuate in a wide range.
[0009]
In other words, the present invention has a d-axis inductance Ld and a q-axis inductance Lq, and the relationship between the rotational speed and the magnetomotive force phase difference angle necessary to obtain the maximum torque with the maximum torque efficiency. And a second maximum torque efficiency curve showing a relationship between a rotational speed and a magnetomotive force phase difference angle necessary for obtaining a predetermined torque smaller than the maximum torque at the maximum torque efficiency. When the rotational speed is taken on the X-axis and the phase angle is taken on the Y-axis, when one of the first and second maximum torque efficiency curves is translated in the X-axis direction and the Y-axis direction, the other substantially overlaps. Power control means for controlling the obtained synchronous motor according to the d-axis current command and the q-axis current command, rotational speed detection means for detecting the rotational speed of the drive shaft of the synchronous motor, and torque command generation means for generating the torque command Tc , Generates a magnetomotive force phase difference angle and a current command calculation means that outputs a current command Ic based on a torque command, and a dq axis current command generation means that outputs a d axis current command and a q axis current command using a magnetomotive force phase difference angle φ. An object of the improvement is a control device for a synchronous motor including a magnetomotive force phase difference angle generating means.
[0010]
In the synchronous motor control device of the present invention, the X-axis direction and the Y-axis required for obtaining a maximum torque efficiency curve for the torque between the maximum torque and a predetermined torque from the first and second maximum torque efficiency curves. The parallel movement coefficients in the X-axis direction and the Y-axis direction for obtaining the amount of parallel movement in the direction are respectively determined in advance, and the magnetomotive force phase difference angle generating means has the maximum torque efficiency with the torque commanded from the torque command at a predetermined rotational speed. The maximum magneto-efficiency curve selected from the first and second maximum torque efficiency curves, the parallel movement coefficient, the torque of one maximum torque efficiency curve, and the command torque From the difference from the torque commanded from
[0011]
In this case, the magnetomotive force phase difference angle is φ, the rotational speed is ωm, the deviation between the first torque command and a torque command smaller than the first torque command, for example, ΔT, the parallel movement coefficients are K1, K2, If the first maximum torque efficiency curve is obtained as φ = F (ωm), when the torque command is another value, φ with respect to ωm is as follows: φ = F (ωm−K1ΔT) −K2ΔT Can be obtained by a simple formula. Since the parallel movement amount does not depend on ωm but only on the deviation value of the torque, the control device for the synchronous motor for maximizing the torque efficiency is obtained by obtaining φ that maximizes the torque efficiency with respect to ωm by a very simple calculation. There is an effect that can be provided.
[0012]
In other words, the present invention has a d-axis inductance Ld and a q-axis inductance Lq, and the relationship between the rotational speed and the magnetomotive force phase difference angle necessary for obtaining the maximum torque with the maximum torque efficiency. The first maximum torque efficiency curve shown shows a constant value as a function of the armature rotation speed when the armature rotation speed is low. As the rotation speed increases, the magnetomotive force phase difference angle begins to increase and gradually increases. When the second maximum torque efficiency curve indicating the relationship between the rotational speed and the magnetomotive force phase difference angle required to obtain a predetermined torque smaller than the maximum torque becomes gentle and the maximum torque efficiency is low, the rotational speed is low. As a function of speed, a constant value lower than that at maximum torque is maintained, and when the rotation speed increases, the rotation speed is higher than at maximum torque and the magnetomotive force phase difference angle is smaller than at maximum torque. One of the first and second maximum torque efficiency curves when the rotational speed is taken on the X axis and the phase angle is taken on the Y axis. Power control means for controlling the synchronous motor in accordance with the d-axis current command and the q-axis current command, and a rotational speed of the drive shaft of the synchronous motor. A rotational speed detecting means for detecting; a torque command generating means for generating a torque command Tc; a current command calculating means for outputting a current command Ic based on the torque command; a d-axis current command using a magnetomotive force phase difference angle φ; A synchronous motor control device comprising a dq-axis current command generating means for outputting a q-axis current command and a magnetomotive force phase difference angle generating means for generating a magnetomotive force phase difference angle is an object of improvement.
[0013]
In the synchronous motor control device of the present invention, the magnetomotive force phase difference angle generating means predetermines the first and second maximum torque efficiency curves by measurement or computer simulation, and the torque command | Tc | When equal to the torque T1, the relationship between the rotational speed ωm and the magnetomotive force phase difference angle φ giving the first maximum torque efficiency curve is

Using φ0, N0, N1, KV1, and KV2 determined in advance so as to be approximated by a broken line including two bending points represented by
However, θ (x) is a step function defined by θ (x) = 1 when x ≧ 0, and θ (x) = 0 when x <0.
Maximum torque efficiency curve when torque command | Tc | smaller than maximum torque T1
φ = G [ωm + K1 · (T1- | Tc |)] − K2 · (T1- | Tc |) (2)
When Tc | = T2 in equation (2), the coefficients between T1 and T2 are set using coefficients K1 and K2 that are predetermined so as to coincide with the second maximum torque efficiency curve. The magnetomotive force phase difference angle φ with respect to the rotational speed ωm and | Tc | is determined using the polygonal line (2) equation including the coefficient obtained as described above with respect to Tc |.
[0014]
In this way, a simple expression of the maximum torque efficiency curve can be realized by observing the calculation result of the characteristics of the synchronous motor and expressing the maximum torque efficiency curve with three broken lines using the observation result. Further, the fluctuation of the maximum torque efficiency curve due to the torque command is simply translated by a vector amount proportional to the deviation between the torque value of the reference maximum torque efficiency curve and the torque value from the torque command regardless of the rotational speed. Can be calculated by the method. As a result, there is an effect that it is possible to provide a control device capable of maximizing the torque efficiency of an electric motor that operates in a wide range of torque values and rotation speed ωm.
[0015]
The present invention also includes a first relationship between a rotational speed and a magnetomotive force phase difference angle required to obtain the maximum torque T1 with the maximum torque efficiency, having a d-axis inductance Ld and a q-axis inductance Lq. When the rotation speed of the armature is low, the maximum torque efficiency curve of FIG. 1 maintains a constant value as a function of the rotation speed of the armature, and when the rotation speed increases, the magnetomotive force phase difference angle starts to increase and gradually increases. When the second maximum torque efficiency curve showing the relationship between the rotational speed and the magnetomotive force phase difference angle required for obtaining the predetermined torque T2 smaller than the maximum torque at the maximum torque efficiency is low, the rotational speed is As a function, a constant value lower than that at the maximum torque is maintained, and when the rotation speed increases, the rotation speed is higher than at the maximum torque and the magnetomotive force phase difference angle is smaller than that at the maximum torque. When the rotational speed is taken on the X axis and the phase angle is taken on the Y axis, one of the first and second maximum torque efficiency curves is taken as the X axis. Power control means for controlling the synchronous motor according to the d-axis current command and the q-axis current command, which can obtain a substantially overlapping relationship with the other when parallelly moving in the direction and the Y-axis direction, and rotation for detecting the rotational speed of the drive shaft of the synchronous motor Speed detection means, torque command generation means for generating a torque command Tc from a deviation between the speed command ωmc and the rotational speed ωm of the motor detected by the rotation speed detection means, and a current command for outputting a current command Ic based on the torque command Synchronous comprising computing means, dq-axis current command generating means for outputting d-axis current command and q-axis current command using magnetomotive force phase difference angle φ, and magnetomotive force phase difference angle generating means for generating magnetomotive force phase difference angle Electric The control device of the machine and improving the subject.
[0016]
In the synchronous motor control device of the present invention, the magnetomotive force phase difference angle generating means determines the first and second maximum torque efficiency curves in advance by measurement or computer simulation, and the torque command | Tc | When equal to the maximum torque T1, the relationship between the rotational speed ωm giving the first maximum torque efficiency curve and the magnetomotive force phase difference angle φ is set in advance so that it can be approximated by a broken line, and shows a constant value when ωm is small. Initial magnetomotive force phase difference angle φ0, first magnetomotive force phase difference angle change speed N0, first speed compensation coefficient KV1 that gives a gradient of a polygonal line at ωm that is N0 or higher, magnetomotive force phase difference The second magnetomotive force phase difference angle changing speed N1 at which the angle starts to increase gradually as a function of the rotational speed, and the second speed compensation coefficient KV2 that gives the gradient of the polygonal line above that are determined in advance. Using the equation of the broken line as a function φT1 of the rotational speed ωm of the electric motor,
φT1 = φ0 + KV1 · (α−N0) + KV2 · (β−N1) (11)
Output by
However, the variables α and β are stored in the first and second storage devices,
When ωm <N0, α = N0, β = N1 (12)
When N0 ≦ ωm <N1, α = ωm, β = N1 (13)
When N1 ≦ ωm, α = N1, β = ωm (14)
A speed compensation means for outputting such φT1 as a function of ωm;
When | Tc | <T1, the change in the maximum torque efficiency function due to the change in | Tc | is represented by a parallel movement proportional to T1- | Tc | from the broken line when | Tc | = T1, and this broken line φ is When the maximum torque efficiency curve | Tc | = T2, the first and second parallel movement coefficients K1 and K2 with respect to T1- | Tc | obtained in advance so as to approximately match the maximum torque efficiency curve. Using,
The first magnetomotive force phase difference angle change speed N0 and the second magnetomotive force phase difference angle change speed N1 at which the magnetomotive force phase difference angle φ starts to increase first, and the second magnetomotive force phase difference angle change speed N1 starts to increase gradually. At the addition point with the product of 1 translation coefficient K1
N0 '= N0 + K1. (T1- | Tc |) (15)
N1 '= N1 + K1. (T1- | Tc |) (16)
The sums N0 'and N1' are input to the speed compensation means, and the equation (11) of the broken line and the inequalities (12), (13), and (14) of ωm that give the straight line portion of the broken line are obtained. Replace N0 and N1 included with N0 ′ and N1 ′, translate the polygonal line in the equation (11) to the right, and the translated polygonal line is φv,
At the third addition point of this translated φv and the product of the difference T1- | Tc |
φ = φv−K2 · (T1− | Tc |) (17)
And a torque compensation means for translating the polygonal line downward,
A limiter is provided that suppresses the output of the speed compensation means and the magnetomotive force phase difference angle φ to a predetermined angle or less.
[0017]
In addition, the speed compensation means uses the variables α and β stored in the first and second storage devices when | Tc | = T1.
When ωm <N0, α = N0, β = N1
When N0 ≦ ωm <N1, α = ωm, β = N1
When N1 ≦ ωm, α = N1, β = ωm
The output speeds α and β of the two storage circuits are subtracted from the rotational speeds N0 and N1 compensated for the torque command at the first and second addition points, respectively, and KV1 and KV2 are subtracted from the respective differences. Multiply the product at the third addition point, and add the sum of φ0 at the fourth addition point to the sum as a velocity compensated magnetomotive force phase difference angle,
When | Tc | <T1,
When ωm <N0 ′, α = N0 ′, β = N1 ′ (18)
When N0 ′ ≦ ωm <N1 ′, α = ωm, β = N1 ′ (19)
When N1 ′ ≦ ωm, α = N1 ′, β = ωm (20)
The rotational speeds N0 ′ and N1 ′ compensated for the torque command at the first and second addition points are subtracted from the outputs α and β of the two storage circuits, respectively, and KV1, The product obtained by multiplying KV2 and adding these products at the third addition point and adding the sum of φ0 at the fourth addition point to the sum may be output as the velocity compensated magnetomotive force phase difference angle.
[0018]
In the synchronous motor control device of the present invention, when the torque command | Tc | takes the value of the maximum torque T1 to 0 torque T0, the coefficient adjusting means has a maximum torque efficiency curve when | Tc | = T1, T2, T0. T1 is set to a torque value equal to any of these, and the maximum torque efficiency curve when | Tc | = T1 can be approximated by a broken line having two bending points. When the magnetomotive force phase difference angle φ0 and the speed compensation coefficients KV1 and KV2 are adjusted, and when | Tc | ≠ T1, a broken line obtained by performing torque compensation using T1- | Tc | instead of TP− | Tc | , T2 ≠ T1, and using T2 equal to any of TP, TR, and T0, the torque-compensated broken line when | Tc | = T2 approximately matches the maximum torque efficiency curve at this time. K1, 2, the magnetomotive force phase difference angle generating means performs torque compensation using a relationship between a broken line of ωm and | Tc | versus φ in a torque-compensated broken line in a value between | Tc | and T1 and T2. It may be.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a circuit diagram of an example of an embodiment in which the present invention is applied to a control device for a synchronous motor 1. The synchronous motor 1 includes a rotor in which a plurality of permanent magnets are embedded in a rotor core, and a d-axis inductance Ld that is a direct axis of the permanent magnet and a q-axis inductance Lq that is an orthogonal axis that is orthogonal to the direct axis by an electrical angle. Is an embedded magnet type synchronous motor (hereinafter referred to as “IPM motor”) in which Ld <Lq. Note that the present invention can naturally be applied to a synchronous motor of a type in which a permanent magnet is fixed to the surface of the rotor core. The magnetomotive force phase difference angle φ is an angle formed by the d-axis and the primary current command Ic.
[0020]
In FIG. 1, the torque command generating means 3 calculates a torque command Tc from the deviation between the speed command ωmc and the rotational speed ωm of the synchronous motor 1 detected by the rotational speed detecting means 5. The current command calculation unit 6 outputs a current command Ic based on the torque command from the torque command generation unit 3. The dq axis current command generation means 7 outputs a d axis current command and a q axis current command using a magnetomotive force phase difference angle φ defined as an angle between the current command and the d axis. The magnetomotive force phase difference angle generating means 9 generates a magnetomotive force phase difference angle φ and outputs it to the dq axis current command generating means 7. The power control means 11 drives the synchronous motor 1 in accordance with the d-axis current command and the q-axis current command.
[0021]
The torque command generating means 3 includes a speed controller 3a and an addition point 3b. The speed controller 3a obtains a speed deviation between the speed command signal ωmc and the rotational speed ωm of the synchronous motor detected by the rotational speed detecting means 5 at the addition point 3b, and calculates a torque command Tc from the speed deviation. The rotational speed detecting means 5 is composed of an encoder 5a and a speed detector 5b. The speed detector 5b detects the rotational speed ωm from the rotational position θm detected by the encoder 5a. The current command calculation means 6 includes a current command calculator (KTI) 6a and a limiter 6b. The current command calculator 6a calculates the current command Ic by multiplying the torque command Tc by the current command conversion coefficient KTI. The limiter 6b limits the current command Ic to a constant value. The dq-axis current command generation means 7 is composed of an absolute value generator 7a, a sinφ signal generator 7b, and a cosφ signal generator 7c. The sinφ signal generator 7b calculates the q-axis current command Iqc by multiplying the current command Ic after the limit processing by sinφ. The cosine signal generator 7c calculates the d-axis current command Idc by converting the current command Ic after the limit processing into an absolute value by the absolute value generator 7a and multiplying it by cos φ. The q-axis current command Iqc and the d-axis current command Idc calculated as described above are sent to the power control unit 11.
[0022]
The power controller 11 includes two integral controllers 11a and 11b, a signal generator 11c, first and second coordinate converters 11d and 11e, a current controller 11f, a PWM controller 11g, a power converter 11h, and a current. It comprises detection means 11i.
[0023]
The signal generating means 11c generates a sin θmf signal and a cos θmf signal provided for the first coordinate converter 11d and the second coordinate converter 11e based on the rotational position θmf detected by the encoder 5a.
[0024]
The first coordinate converter 11d receives the output current detected by the current detection unit 11i and the sin θmf signal and the cos θmf signal output from the signal generation unit 11c as input signals, and receives a d-axis current feedback signal Idf and a q-axis current feedback signal Iqf. Is output.
[0025]
The second coordinate converter 11e takes the difference between the q-axis current command Iqc and the q-axis electric feedback Iqf, and adds this difference through the integration controller 11a at the q-axis current command Iqc and the addition point 11a to obtain an integral compensation amount. Q-axis current command Iqc ′ including Similarly, Idc ′ is also obtained. Iqc ′ and Iqc ′ are obtained through the second coordinate converter 11e to obtain three-phase current commands IUc, IVc and IWc. In the current controller 11f, a deviation from the current feedback is taken and proportionally calculated to obtain the voltage commands VUc, VVc, VWc. This is passed through the PWM controller 11g, and the IPM motor 1 is driven by the power converter 11h.
[0026]
The magnetomotive force phase difference angle generating means 9 generates a maximum torque more than the first data curve showing the relationship between the rotational speed ωm and the magnetomotive force phase difference angle φ necessary for obtaining the maximum torque efficiency and the maximum torque. The maximum torque and the predetermined torque at the predetermined rotational speed based on the second data curve showing the relationship between the rotational speed and the magnetomotive force phase difference angle necessary for obtaining the maximum torque efficiency when generating the small predetermined torque. The magnetomotive force phase difference angle φ required to generate the torque between the two at a maximum torque efficiency is determined.
[0027]
FIG. 2 shows the magnetomotive force phase difference angle at which the torque efficiency becomes maximum when the rated torque and the maximum torque in the case of the IPM motor to be controlled in this embodiment are obtained by simulation. The magnetomotive force phase difference angle at which the torque efficiency is maximized is different between the maximum torque and the rated torque, and at the rated torque, the torque efficiency is maximized with a smaller magnetomotive force phase difference angle than at the maximum torque. In the rated torque curve, when the rotation speed of the armature is low, a constant value is maintained as a function of the rotation speed of the armature, and when the rotation speed increases, the magnetomotive force phase difference angle starts to increase and gradually increases gradually. . When there is no magnetic saturation in the IPM motor, the torque of the IPM motor is obtained as the sum of the relatance torque and the magnet torque, so that the torque efficiency is maximized in the vicinity of the magnetomotive force phase difference angle of 120 to 135 °. The magnetomotive force phase difference angle when the rotational speed is low at the rated torque corresponds to this. When the rotational speed increases, the motor voltage increases, so that the magnetomotive force phase difference angle increases as the rotational speed increases so as not to exceed the output voltage of the power converter. In the maximum torque curve, when the rotational speed is low, a constant value higher than the rated torque is maintained as a function of the rotational speed, and when the rotational speed is high, the magnetomotive force phase difference angle is at a lower rotational speed than the rated torque. Starts to increase to a value larger than that at the maximum torque, and gradually increases gradually. At the maximum torque, the maximum torque efficiency is obtained by slightly increasing the magnetomotive force phase difference angle and relaxing the magnetic saturation. Further, since the motor voltage is higher than that at the rated torque, it is necessary to increase the magnetomotive force phase difference angle from a lower rotational speed than at the rated torque. Accordingly, when one of the maximum torque efficiency curves at the maximum torque and the rated torque is translated in the horizontal axis direction and the vertical axis direction, the relationship is almost overlapped with the other. The present invention provides a control device that effectively utilizes the characteristics of the synchronous motor.
[0028]
FIG. 3 is a graph for explaining the operation of the first embodiment shown in FIG. The vertical axis represents the magnetomotive force phase difference angle φ, and the horizontal axis represents the rotational speed ωm. In FIG. 3, the three broken lines indicate the maximum values obtained by experiments or simulations as shown in FIG. 2 when | Tc | is the maximum torque (TP), rated torque (TR), and torque 0 (TO). A broken line approximating the torque efficiency curve is shown.
[0029]
As shown in FIG. 1, the magnetomotive force phase difference angle generating means 9 includes a speed compensating means 13, first and second torque compensating means 15, and a limiter 17. When the torque command | Tc | is equal to the first maximum torque T1, the speed compensation means 13 can approximate the relationship between the rotational speed ωm and the magnetomotive force phase difference angle φ that gives the first maximum torque efficiency curve by a broken line. It is determined beforehand as follows. As constants for determining the polygonal line, the initial magnetomotive force phase difference angle φ0, which is a constant value when ωm is small, the first magnetomotive force phase difference angle changing speed N0 at which the magnetomotive force phase difference angle starts to increase rapidly, the first magnetomotive force phase difference Speed compensation coefficient KV1 that gives the gradient of the polygonal line at ωm at the angle change speed N0 or higher, second magnetomotive force phase difference angle change speed N1 at which the magnetomotive force phase difference angle begins to increase gradually as a function of the rotational speed, and a polygonal line at the higher speed A speed compensation coefficient KV2 that gives a gradient of is used. Using these constants, the speed compensation means 13 takes the equation of the broken line as a function φT1 of the rotational speed ωm of the motor.
φT1 = φ0 + KV1 · (α−N0) + KV2 · (β−N1) (21)
To output.
[0030]
However,
When ωm <N0, α = N0, β = N1 (22)
When N0 ≦ ωm <N1, α = ωm, β = N1 (23)
When N1 ≦ ωm, α = N1, β = ωm (24)
It shall be changed as follows.
[0031]
The magnetomotive force phase difference angle φT1 obtained in this way becomes a line graph of | Tc | = T1 = TP shown in FIG. 3 as a function of ωm.
[0032]
In the range of ωm from 0 to N0, when α = N0 and β = N1 in ωm <N0 are substituted in Equation (1), only the first term on the right side remains. Therefore,
φT1 = φ0 (25)
It becomes a constant value such as
[0033]
When ωm is N0 to N1, substituting α = ωm and β = N1 when N0 ≦ ωm <N1 in equation (1),
φT1 = φ0 + KV1 · (ωm−N0) (26)
Thus, the second term is added to form a broken line of the speed compensation coefficient KV1 that gives a gradient that bends at ωm = N0.
[0034]
When ωm is greater than or equal to N1, substituting α = N1 and β = ωm when N1 ≦ ωm,
φT1 = φ0 + KV1 · (N1−N0) + KV2 · (ωm−N1) (27)
Thus, the third term is added to form a broken line of the speed compensation coefficient KV2 that gives a gradient that bends at ωm = N1.
[0035]
FIG. 4 shows an example of the configuration of the speed compensation means 13 shown in the embodiment of FIG. The speed compensation means 13 includes storage devices 13a and 13b, speed compensation coefficient calculators 13c and 13d, and addition points 13e, 13f, 13g, and 13h. Magnetomotive force phase difference angle changing speeds N0, N1, initial magnetomotive force phase difference angle φ0, speed compensation coefficients KV1, KV2 are input as parameters to speed compensation means 13, and ωm is used as an input variable. The variables α and β stored in the first and second storage devices 13a and 13b are set when | Tc | = T1.
When ωm <N0, α = N0, β = N1 (28)
When N0 ≦ ωm <N1, α = ωm, β = N1 (29)
When N1 ≦ ωm, α = N1, β = ωm (30)
Change as follows. The outputs α and β from the two internal storage circuits 13a and 13b are subtracted from the magnetomotive force phase difference angle changing speeds N0 and N1 compensated for the torque command at the addition points 13e and 13f, respectively, and a speed compensation coefficient is calculated for each difference. Multipliers 13c and 13d multiply speed compensation coefficients KV1 and KV2, add the products at addition point 13g, and add the sum to φ0 at addition point 13h, and output it as speed-compensated magnetomotive force phase difference angle φT1. To do.
[0036]
When | Tc | <T1, the torque compensator 15 operates. The torque compensator 15 includes a first translation coefficient calculator 15a, a second translation coefficient calculator 15d, and addition points 15b, 15c, and 15e. The translation coefficient calculator 15a translates the polygonal line at the torque command | Tc | = T1 to K1 · (T1- | Tc |) in the right direction in proportion to T1- | Tc |. The computing unit 15d translates in the downward direction by K2 · (T1- | Tc |). At this time, as shown in FIG. 3, the parallel movement coefficients K1 and K2 are such that the broken line when | Tc | = T2 = TR approximately matches the maximum torque efficiency curve when | Tc | = T2. Determine in advance. The first and second torque compensating means perform the lateral translation and the descending translation as follows using the speed compensation coefficients K1 and K2 determined in advance as described above.
[0037]
In FIG. 1, the torque compensator 15 uses the first translation coefficient calculator 15a to calculate the product K1 · (T1- | Tc |) of the torque input deviation (T1- | Tc |) and the translation coefficient K1. This product and the magnetomotive force phase difference angle changing speeds N0 and N1, which are the abscissas of the bending points, are added at the addition points 15b and 15c as follows:
N0 '= N0 + K1, (T1- | Tc |) (31)
N1 '= N1 + K1. (T1- | Tc |) (32)
Thus, torque-compensated magnetomotive force phase difference angle changing speeds N0 ′ and N1 ′ are calculated and input to the speed compensating means 13.
[0038]
The speed compensation means 13 uses the magnetomotive force phase difference angle changing speeds N0 and N1 included in φT1 in the expression (21) as follows:
φv = φ0 + KV1 · (α−N0 ′) + KV2 · (β−N1 ′) (33)
Thus, the magnetomotive force phase difference angle φv of the broken line replaced with N0 ′ and N1 ′ is output. φv is a broken line translated as a function of ωm in the right direction with respect to the broken line of | Tc | = T1 = TP.
[0039]
However, the storage contents α and β of the first and second storage devices 13a and 13b are:
When ωm <N0 ′, α = N0 ′, β = N1 ′ (34)
When N0 ′ ≦ ωm <N1 ′, α = ωm, β = N1 ′ (35)
When N1 ′ ≦ ωm, α = N1 ′, β = ωm (36)
The abscissa is also moved in parallel by changing the bending point.
[0040]
In FIG. 4, when | Tc | <T1, magnetomotive force phase difference angle changing speeds N0 'and N1', initial magnetomotive force phase difference angle φ0, speed compensation coefficients KV1 and KV2 are input as parameters to speed compensation means 13, and ωm is input. Variable. The variables α and β stored in the first and second storage devices 13a and 13b are changed as in the above equations (34) to (36).
[0041]
The outputs α and β from the two storage circuits 13a and 13b are subtracted from the magnetomotive force phase difference angle changing speeds N0 ′ and N1 ′ at the addition points 13e and 13f, respectively, and the speed compensation coefficient KV1 is subtracted from each difference. , KV2, and the product is added at an addition point 13g, and φ0 is added to the sum at addition point 13h.
[0042]
The torque compensator 15 adds the magnetomotive force phase difference angle φv of the output of the speed compensator 13 and the product obtained by multiplying the difference T1- | Tc | by the second translation coefficient calculator 15d by the translation coefficient K2 to the addition point 15e. In the following formula
φ = φv−K2 · (T1− | Tc |) (37)
Then, the broken line φv in the equation (33) is translated in the vertical direction, and the magnetomotive force phase difference angle φ in the equation (37) is output as the magnetomotive force phase difference angle φ with respect to the rotational speed ωm at | Tc | <T1.
[0043]
The limiter 17 suppresses the magnetomotive force phase difference angle φ, which is the output of the speed compensation means 13, to a predetermined angle or less. The limiter 17 limits φ to 90 to 180 °, and sets the magnetomotive force phase difference angle φ after various compensations.
[0044]
When the torque command | Tc | is equal to or lower than the rated torque TR and equal to or higher than T0 in FIG. 3, that is, when T0 <Tc <TR, the same relationship as described above can be used with T1 = TR and T2 = T0. Alternatively, when T1 = T0 and T2 = TR, torque compensation and speed compensation can be performed using | Tc | instead of T1- | Tc |
[0045]
An example of the second embodiment of the present invention will be described with reference to FIG. In the present embodiment, the magnetomotive force phase difference angle generating means 9 generates the magnetomotive force phase difference angle φ for controlling the synchronous motor shown in the embodiment of FIG. 1 as follows.
[0046]
Step S1: The magnetomotive force phase difference angle generating means 9 previously determines first and second maximum torque efficiency curves as shown in FIG. 2 by measurement or computer simulation. The first and second torque commands | Tc | can be selected as a set of two different torque commands, for example, any one of the maximum torque TP, the rated torque TR, and the zero torque T0.
[0047]
Step S2: The maximum torque efficiency function relationship when | Tc | = T1 is approximated by a broken line including two bending points as in the following equation.
[0048]

However, the step function θ (x) is defined as θ (x) = 1 when x ≧ 0, and θ (x) = 0 when x <0. Here, when ωm is between 0 and N0, φ becomes a constant value φ0 of only the first term. When ωm is between N0 and N1, the second term is added to form a polygonal line with the gradient KV1. When ωm is greater than or equal to N1, the second term is a constant value, and the third term is added to form a polygonal line with the gradient KV2. Φ 0, N 0, N 1, KV 1, and KV 2 are determined in advance so that this broken line is expressed by an approximation having a good relationship with the maximum torque efficiency function.
[0049]
Step S3: The maximum torque efficiency curve when | Tc |
φ = G [ωm−K1 · (T1− | Tc |)] − K2 · (T1− | Tc |) (39)
It is approximated by a polygonal line that is translated as Here, the parallel movement coefficients K1 and K2 are determined so that the polygonal line that has been translated coincides with the maximum torque efficiency curve when | Tc | = T2.
[0050]
Step S4: The magnetomotive force phase difference angle φ with respect to the rotational speeds ωm and | Tc | is determined using the polygonal line (39) equation in which constants are determined as described above for | Tc | between T1 and T2. .
[0051]
FIG. 5 is a diagram used for explaining the third embodiment of the present invention. In this embodiment, the magnetomotive force phase difference angle generating means 9 shown in the embodiment of FIG. 1 generates the magnetomotive force phase difference angle φ as follows.
[0052]
Step S1: The magnetomotive force phase difference angle generating means 9 predetermines the first and second maximum torque efficiency curves by measurement or computer simulation. The first and second torque commands | Tc | can be selected from two different torque command sets of the maximum torque TP, the rated torque TR, and the zero torque T0.
[0053]
Step S2: The maximum torque efficiency curve when | Tc | = T1 is
φ = F (ωm) (40)
And As the form of the expression of F (ωm), for example, a result obtained by approximating the result of numerical calculation with a simple polynomial may be used. For example, in order to determine a polynomial that coincides with F (ωm) at N points, an N−1 order polynomial may be used. In this case, since N coefficients are required, if N function values are determined, N coefficients are determined. Such a determination method can be expected to have an effect of improving the accuracy of approximation rather than the polygonal line approximation.
[0054]
Step S3: The maximum torque efficiency curve when | Tc |
φ = F [ωm + K1 · (T1- | Tc |)] − K2 · (T1- | Tc |) (41)
Translate like this. The parallel movement coefficients K1 and K2 are determined so as to coincide with the maximum torque efficiency curve when | Tc | = T2 by, for example, the least square method.
[0055]
Step S4: φ is determined from ωm by using equation (41) for | Tc | between T1 and T2.
[0056]
FIG. 6 is a graph used for explaining an example of the fourth embodiment of the present invention. In this embodiment, the magnetomotive force phase difference angle generating means 9 shown in the embodiment of FIG. 1 outputs the magnetomotive force phase difference angle φ according to the following steps.
[0057]
Step S1: As shown in FIG. 2, the maximum torque efficiency curve between the motor rotational speed ωm and the magnetomotive force phase difference angle φ at which the torque efficiency is maximum is shown, and the torque command is the maximum torque TP, rated torque TR, and torque 0 It calculates | requires previously with respect to T0. In the following, when the torque command Tc is | Tc | = TP, TR, T0, it is written as | Tc | = T (i) (i = 0, 1, 2). For convenience of explanation, such a torque command value is selected as an example, but it can be generalized when a maximum torque efficiency curve for a plurality of torque values is used. In the present embodiment, the maximum torque T (0) corresponds to the maximum torque T1 in claim 7 of the present invention. In this embodiment, the rated torque T (1) is an example of the seventh aspect of the present invention, wherein the predetermined torque T2 is smaller than the maximum torque. The three torque cases of the present embodiment are generalized from the two torque cases of the seventh aspect.
[0058]
Step S2: The functional relationship between the magnetomotive force phase difference angle φ and the rotational speed ωm in the three maximum torque efficiency curves obtained in Step S1 is approximated by a broken line made up of the same number of bending points as shown in FIG. Then, the bending points of each broken line are associated with each other in the same order. For example, the numbers from 1 to N-1 are assigned to the bending points, and 0 is the start point and N is the end point. The bending points including the starting point and the ending point from 0 to N are set to j = 0 to N by the number j, respectively. The coordinates of the bending point (i, j) (i = 0 to 2, j = 0 to N) of the number j of the broken line with the number i on the ωm-φ plane, where the horizontal axis is ωm and the vertical axis is φ, Let (i, j) and φ (i, j). The number of bending points of the broken line that approximates the i-th maximum torque efficiency curve is the same number N-1, and the j-th bending point of each broken line is a bending point of number j corresponding to each other.
[0059]
Step S3: When the magnitude | Tc | of the torque command Tc takes a value between two torque values T (i) and T (i + 1), the magnetomotive force phase difference that maximizes the torque efficiency with respect to the rotational speed ωm. Find the angle φ. Hereinafter, i = 0 is fixed. The following story holds true when i = 1 is fixed. In order to approximately obtain the portion of the maximum torque efficiency curve necessary for obtaining the magnetomotive force phase difference angle φ, first, a quadrilateral as shown in FIG. 6B is determined. That is, in FIG. 6B, a straight line section that approximates the maximum torque efficiency curve that maximizes the torque efficiency at the i-th torque value T (i), that is, two bending points (N (i, j ), Φ (i, j)) and (N (i, j + 1), φ (i, j + 1)) and the maximum torque efficiency that maximizes the torque efficiency at the i + 1th torque value T (i + 1) A straight line section that approximates a curve, that is, a line connecting two bending points (N (i + 1, j), φ (i + 1, j)) and (N (i + 1, j + 1), φ (i + 1, j + 1)) Here, the value of j is selected so as to satisfy the relationship of N (i, j) <ωm <N (i, j + 1). It is a point at both ends of the opposite side of the side, and the corresponding jth, j + 1th respectively The points are in the same order, where j is one number from 0 to N-1.
[0060]
Step S4: Among the points on both sides of the opposite side forming the quadrilateral obtained in Step S3, the j-th points (N (i, j), φ (i, j)) and (N (i + 1, j)), A first inner point (N (| Tc |,) that internally divides the first side connecting φ (i + 1, j) into a ratio of T (i) − | Tc |: | Tc | −T (i + 1). j) and φ (| Tc |, j)) are obtained by the following equations.
[0061]

Step S5: Similarly, among the points at both ends of the opposite side forming the quadrilateral obtained in Step S3, the j + 1-th points (N (i, j + 1), φ (i, j + 1)) and (N (i + 1, j + 1) and φ (i + 1, j + 1) are divided into a ratio T (i) 1- | Tc |: | Tc | -T (i + 1). | Tc |, j + 1), φ (| Tc |, j + 1)) is obtained by the following equation.
[0062]

Step S6: It is determined that the rotational speed ωm obtained from the rotational speed detecting means 5 is within the range of the line segment connecting N (| Tc |, j) to N (| Tc |, j + 1)]. Thus, when the quadrilateral is selected in step S3, it is selected so as to be like this. If not, the process returns to step S3. When ωm <N (i + 1, j), j is set to j + 1. When ωm> φ (i + 1, j + 1), j is set to j−1 and the condition is satisfied. Steps S3 to S6 are repeated until. If the condition is satisfied, proceed to the next step.
[0063]
Step S7: When the condition of step S6 is satisfied, the equation of the line segment connecting these internal dividing points is given by the relationship of the linear expression of ωm and φ as shown in the following expression.
[0064]

Thus, φ is determined from ωm.
[0065]
Step S8: φ for ωm is output.
[0066]
FIG. 7 is an actual measurement result of a rise in motor coil temperature during rated operation in the conventional method and this method. From this, it can be seen that this method can greatly improve the torque efficiency at the rated rotational speed.
[0067]
According to the above embodiments, the following effects can be obtained.
[0068]
(1) Since the torque efficiency of the motor can be maximized not only in the maximum torque region but also in the rated torque region, it is possible to provide a motor control device with high efficiency and low energy consumption.
[0069]
(2) The motor can be designed to be smaller and lighter.
[0070]
(3) Since the magnetomotive force phase difference angle from the torque 0 to the maximum torque is controlled in proportion to the difference between the maximum torque and the absolute value of the torque command, the torque can be adjusted with a small number of motor parameters. Also, torque adjustment based on the maximum torque is possible.
[0071]
【The invention's effect】
As in the present invention, when the magnetomotive force phase difference angle is controlled by the torque command and the rotation speed, the torque efficiency of the motor is maximized not only in the maximum torque region but also in a predetermined torque region smaller than the maximum torque. A control device for a synchronous motor having a simple structure that can be controlled can be obtained. As a result, according to the present invention, there is an effect that the electric motor can be operated while the torque efficiency is always kept at the maximum even when the torque command and the rotational speed fluctuate in a wide range.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an example of a control apparatus for a synchronous motor according to a first embodiment of the present invention.
FIG. 2 is a simulation result of characteristics of a synchronous motor to be controlled by the present invention.
FIG. 3 shows a result obtained by approximating a simulation result of characteristics of a synchronous motor to be controlled by the present invention by a polygonal line.
FIG. 4 is a block diagram showing details of a part of the control apparatus for the synchronous motor according to the first embodiment of the present invention.
FIG. 5 is a diagram illustrating a method for approximating a parallel translation of a torque compensation curve.
FIGS. 6A and 6B are diagrams for explaining a method using a polygonal line approximation and an internal dividing point. FIGS.
FIG. 7 is a diagram for explaining the effect of the present invention.
FIG. 8 is a diagram for explaining a conventional control method of a synchronous motor.
[Explanation of symbols]
1 IPM motor
3 Torque command generation means
3a Speed controller
3b Additional points
5 Rotation speed detection means
5a Encoder
5b Speed detector
6a Current command calculator
6b Limiter
7 dq axis current command generation means
7a Absolute value converter
7b sin signal generator
7c cos signal generator
9 Magnetomotive force phase difference angle generation means
11 Power control means
11a, 11b integral controller
11c signal generator
11d first coordinate converter
11e Second coordinate converter
11f Current controller
11g PWM controller
11h power converter
11i Current detection means
11s, 11t, 11u, 11v addition points
13 Speed compensation means
13a, 13b memory circuit
13c KV1
13d KV2
13e, 13f, 13g, 13h Additional points
15 Torque compensation means
15b, 15c, 15e Additional points
17 Limiter

Claims (6)

power control means for controlling a synchronous motor having a d-axis inductance Ld and a q-axis inductance Lq according to a d-axis current command and a q-axis current command;
Rotation speed detection means for detecting the rotation speed of the drive shaft of the synchronous motor;
Torque command generating means for generating a torque command Tc;
Current command calculation means for outputting a current command Ic based on the torque command;
Dq-axis current command generating means for outputting the d-axis current command and the q-axis current command using a magnetomotive force phase difference angle φ defined as an angle between the current command and the d-axis current command ;
A control apparatus for a synchronous motor comprising a magnetomotive force phase difference angle generating means for generating the magnetomotive force phase difference angle,
The magnetomotive force phase difference angle generating means generates a maximum torque, the first data curve showing the relationship between the rotational speed ωm and the magnetomotive force phase difference angle φ necessary for obtaining the maximum torque efficiency, and the maximum Based on the second data curve indicating the relationship between the rotational speed and the magnetomotive force phase difference angle required to obtain the maximum torque efficiency when generating a predetermined torque smaller than the torque, at a predetermined rotational speed 2. A control apparatus for a synchronous motor, wherein the magnetomotive force phase difference angle φ required to generate a torque between the maximum torque and a predetermined torque with maximum torque efficiency is determined. a first maximum torque efficiency curve having a d-axis inductance Ld and a q-axis inductance Lq, and showing a relationship between a rotational speed and a magnetomotive force phase difference angle necessary for obtaining the maximum torque with the maximum torque efficiency; A second maximum torque efficiency curve showing a relationship between the rotational speed and the magnetomotive force phase difference angle necessary for obtaining a predetermined torque smaller than the maximum torque at the maximum torque efficiency, and representing the rotational speed on the X axis. However, when the magnetomotive force phase difference angle is taken on the Y-axis, when one of the first and second maximum torque efficiency curves is translated in the X-axis direction and the Y-axis direction, a relationship that substantially overlaps the other is obtained. Power control means for controlling the synchronous motor according to the d-axis current command and the q-axis current command;
Rotation speed detection means for detecting the rotation speed of the drive shaft of the synchronous motor;
Torque command generating means for generating a torque command Tc;
Current command calculation means for outputting a current command Ic based on the torque command;
Dq-axis current command generating means for outputting the d-axis current command and the q-axis current command using the magnetomotive force phase difference angle φ ;
A magnetomotive force phase difference angle generating means for generating the magnetomotive force phase difference angle;
A translation amount in the X-axis direction and the Y-axis direction necessary to obtain a maximum torque efficiency curve for the torque between the maximum torque and the predetermined torque from the first and second maximum torque efficiency curves. Respectively, a translation coefficient in the X-axis direction and the Y-axis direction for obtaining
The magnetomotive force phase difference angle generating means calculates the magnetomotive force phase difference angle required to achieve the maximum torque efficiency with the torque commanded from the torque command at a predetermined rotational speed, and the first and second maximum torque efficiency curves. One of the maximum torque efficiency curves selected from the above, the parallel movement coefficient, and the difference between the torque commanded from the command torque and the torque of the one maximum torque efficiency curve. The control apparatus of the synchronous motor characterized by this. A first maximum torque efficiency curve having a d-axis inductance Ld and a q-axis inductance Lq and showing a relationship between a rotational speed and a magnetomotive force phase difference angle necessary for obtaining the maximum torque with the maximum torque efficiency is as follows. When the rotation speed of the armature is low, a constant value is maintained as a function of the rotation speed of the armature, and when the rotation speed increases, the magnetomotive force phase difference angle starts to increase, and then gradually increases gradually, and the maximum torque efficiency The second maximum torque efficiency curve showing the relationship between the rotational speed necessary for obtaining a predetermined torque smaller than the maximum torque and the magnetomotive force phase difference angle is a function of the rotational speed when the rotational speed is low. As the maximum torque, the constant value lower than that at the maximum torque is maintained, and when the rotation speed increases, the magnetomotive force phase difference angle increases at the rotation speed higher than that at the maximum torque. When the rotation speed is taken on the X axis and the phase angle is taken on the Y axis. Power control means for controlling a synchronous motor, which can obtain a substantially overlapping relationship when one of the two maximum torque efficiency curves is translated in the X-axis direction and the Y-axis direction according to the d-axis current command and the q-axis current command; ,
Rotation speed detection means for detecting the rotation speed of the drive shaft of the synchronous motor;
Torque command generating means for generating a torque command Tc;
Current command calculation means for outputting a current command Ic based on the torque command;
Dq-axis current command generating means for outputting a d-axis current command and a q-axis current command using the magnetomotive force phase difference angle φ ;
A magnetomotive force phase difference angle generating means for generating the magnetomotive force phase difference angle;
The magnetomotive force phase difference angle generating means predetermines the first and second maximum torque efficiency curves by measurement or computer simulation, and the magnitude | Tc | of the torque command Tc becomes the first maximum torque T1. When equal, the relationship between the rotational speed ωm giving the first maximum torque efficiency curve and the magnetomotive force phase difference angle φ is expressed by the following equation: φ = G (ωm)
= Φ0 + KV1 · [θ (ωm−N0) · (ωm−N0) −θ (ωm−N1) · (ωm−N1)] + KV2 · θ (ωm−N1) · (ωm−N1) (1)
Approximated by a polyline containing two bend points represented by
In the above equation (1), φ0 is the initial magnetomotive force phase difference angle, N0 and N1 are the first and second magnetomotive force phase difference angle changing speeds, and KV1 and KV2 are the first and second speed compensation coefficients. And
Θ (x) is a step function defined by θ (x) = 1 when x ≧ 0, and θ (x) = 0 when x <0.
When the torque command | Tc | is smaller than the maximum torque T1, the maximum torque efficiency curve is φ = G [ωm + K1 · (T1- | Tc |)] − K2 · (T1- | Tc |) (2)
The first and second predetermined values are set so as to coincide with the second maximum torque efficiency curve when the second torque command | Tc | = T2 in the equation (2). Using the second translation coefficients K1 and K2,
The synchronous motor characterized in that the magnetomotive force phase difference angle φ with respect to the rotational speed ωm and the torque command | Tc | is determined by using the equation (2) for | Tc | between T1 and T2. Control device. A first maximum torque efficiency curve having a d-axis inductance Ld and a q-axis inductance Lq and showing a relationship between a rotational speed and a magnetomotive force phase difference angle necessary for obtaining the maximum torque T1 with the maximum torque efficiency. However, when the rotation speed of the armature is low, a constant value is maintained as a function of the rotation speed of the armature, and when the rotation speed increases, the magnetomotive force phase difference angle begins to increase, and gradually increases gradually. The second maximum torque efficiency curve showing the relationship between the rotational speed and the magnetomotive force phase difference angle necessary for obtaining a predetermined torque T2 smaller than the torque is the maximum torque as a function of the rotational speed when the rotational speed is low. The constant value lower than that at the time of the above is maintained, and when the rotational speed becomes high, the magnetomotive force phase difference angle is smaller than that at the maximum torque at a rotational speed higher than that at the maximum torque. Of the first and second maximum torque efficiency curves when the rotational speed is taken on the X axis and the phase angle is taken on the Y axis. Power control means for controlling a synchronous motor according to a d-axis current command and a q-axis current command, in which a relationship of substantially overlapping the other is obtained when one side is translated in the X-axis direction and the Y-axis direction;
Rotation speed detection means for detecting the rotation speed of the drive shaft of the synchronous motor;
Torque command generating means for generating a torque command Tc;
Current command calculation means for outputting a current command Ic based on the torque command;
Dq-axis current command generating means for outputting a d-axis current command and a q-axis current command using the magnetomotive force phase difference angle φ ;
A magnetomotive force phase difference angle generating means for generating the magnetomotive force phase difference angle;
The first and second maximum torque efficiency curves used for the magnetomotive force phase difference angle generating means are respectively determined in advance by measurement or computer simulation,
When the torque command | Tc | is equal to the first maximum torque T1, the relationship between the rotational speed ωm that gives the first maximum torque efficiency curve and the magnetomotive force phase difference angle φ can be approximated by a broken line. In addition, the initial magnetomotive force phase difference angle φ0, which is a constant value when ωm is small, the first magnetomotive force phase difference angle changing speed N0 at which the magnetomotive force phase difference angle starts to increase rapidly, and the slope of the polygonal line at ωm at the speed N0 or higher are shown. The first speed compensation coefficient KV1 to be given, the second magnetomotive force phase difference angle changing speed N1 at which the magnetomotive force phase difference angle starts to increase gradually as a function of the rotational speed, and the second speed compensation to give the gradient of the polygonal line at the speed N1 or higher. A coefficient KV2 is determined in advance, and using these constants, the equation of the broken line is obtained as the function φT1 of the rotational speed ωm of the motor from the following equation:
φT1 = φ0 + KV1 · (α−N0) + KV2 · (β−N1) (1)
However, the variables α and β are stored in the first and second storage devices,
When ωm <N0, α = N0, β = N1 (2)
When N0 ≦ ωm <N1, α = ωm, β = N1 (3)
When N1 ≦ ωm, α = N1, β = ωm (4)
Speed compensation means for outputting the magnetomotive force phase difference angle φT1 as a function of the rotational speed ωm;
When the torque command is | Tc | <T1, the change in the maximum torque efficiency function due to the change in the torque command | Tc | is proportional to T1- | Tc | from the broken line when | Tc | = T1. It is represented by a parallel broken line, and when the torque command is | Tc | = T2, T1− obtained in advance so that the parallel broken line approximately matches the second maximum torque efficiency curve. Using the first and second translation coefficients K1, K2 for | Tc |
The first magnetomotive force phase difference angle changing speed N0 at which the magnetomotive force phase difference angle φT1 starts to increase first and the second magnetomotive force phase difference angle changing speed N1 at which the magnetomotive force phase difference angle φT1 starts to increase gradually are set to T1. N0 ′ = N0 + K1 · (T1− | Tc |) (5) at the addition point of the product obtained by multiplying − | Tc | by the first translation coefficient K1.
N1 '= N1 + K1. (T1- | Tc |) (6)
The sum, the first and second torque compensated magnetomotive force phase difference angle changing speeds N0 'and N1' are input to the speed compensating means, and the broken line equation (1) and the broken line The magnetomotive force phase difference angle changing speeds N0 and N1 included in the inequalities (2), (3), and (4) of ωm giving the range of the straight line portion are replaced with the magnetomotive force phase difference angle changing speeds N0 ′ and N1 ′. Then, the polygonal line φT1 represented by the formula (1) is translated in the right direction, and the translated polygonal line is defined as φv.
The first translational broken line φv and the product obtained by multiplying the difference T1- | Tc | by the second translation coefficient K2 are expressed by the following equation: φ = φv−K2 · (T1− | Tc | (7)
And a torque compensation means for translating the polygonal line downward,
A control device for a synchronous motor, comprising: a limiter that suppresses an output of the speed compensation means to be equal to or less than a predetermined angle of the magnetomotive force phase difference angle φ. The speed compensation means sets the variables α and β stored in the first and second storage devices to α = N0 and β = N1 when ωm <N0 when | Tc | = T1.
When N0 ≦ ωm <N1, α = ωm, β = N1 (3)
When N1 ≦ ωm, α = N1, β = ωm (4)
The magnetomotive force phase difference angle changing speeds N0 and N1 are subtracted from the outputs α and β of the two storage circuits at the first and second addition points, respectively, and a speed compensation coefficient is calculated for each difference. Multiplying KV1 and KV2 and adding the products at the third addition point, and adding the initial sum magnetomotive force phase difference angle φ0 at the fourth addition point to the sum as the speed compensated magnetomotive force phase difference angle φv When | Tc | <T1,
When ωm <N0 ′, α = N0 ′, β = N1 ′ (8)
When N0 ′ ≦ ωm <N1 ′, α = ωm, β = N1 ′ (9)
When N1 ′ ≦ ωm, α = N1 ′, β = ωm (10)
And the magnetomotive force phase difference angle changing speeds N0 ′ and N1 ′ compensated for the torque command at the first and second addition points, respectively, to the outputs α and β of the two storage circuits. Subtract, multiply each difference by speed compensation coefficients KV1 and KV2, add the products at the third addition point, and add the sum of φ0 at the fourth addition point to the sum, then the magnetomotive force whose speed is compensated 5. The synchronous motor control device according to claim 4, wherein the synchronous motor control device outputs the phase difference angle φv. When the torque command | Tc | takes the value of the maximum torque T1 to 0 torque T0, the maximum torque efficiency curve when | Tc | = T1, T2, T0 is obtained,
T1 is set to a torque value equal to any one of these, and the maximum torque efficiency curve when | Tc | = T1 can be approximated by a broken line having two bending points, the velocity coordinates N0, N1, the initial magnetomotive force phase difference. Adjust the angle φ0 and the speed compensation coefficients KV1, KV2,
When | Tc | ≠ T1, a polygonal line subjected to torque compensation using T1- | Tc |, and T2 equal to any of TP, TR, and T0 at T2 ≠ T1, and | Tc | = T2 K1 and K2 are determined so that the torque-compensated broken line at this time approximately matches the maximum torque efficiency curve at this time,
The magnetomotive force phase difference angle generating means performs torque compensation by using a relation between ωm and | Tc | versus φ, which is a torque-compensated broken line at a value between | Tc | and T1 to T2. Item 6. The control apparatus for a synchronous motor according to any one of Items 4 to 5.

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