JP3716347B2

JP3716347B2 - Induction motor drive device, induction motor control device, and induction motor control method

Info

Publication number: JP3716347B2
Application number: JP2002148829A
Authority: JP
Inventors: 浩一郎永田; 俊昭奥山; 茂俊岡松; 治郎根本; 敏男片山
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 2002-05-23
Filing date: 2002-05-23
Publication date: 2005-11-16
Anticipated expiration: 2022-05-23
Also published as: JP2003348897A

Description

【０００１】
【発明の属する技術分野】
本発明は，誘導電動機をベクトル制御により可変速制御する駆動装置に係り、具体的には起動ないし加速時における制御技術に属する。
【０００２】
【従来の技術】
誘導電動機をベクトル制御により可変速制御する場合、速度指令値ωr*にすべり周波数ωsを加算してインバータの周波数指令値ω1*を求め、これに基づいてｄ軸電圧指令値Ｖd*、ｑ軸電圧指令値Ｖq*及び位相θを演算して、誘導電動機に供給する交流電圧をベクトル制御して速度を可変している。つまり、周波数指令値ω1*に対応した位相θによりＶd*、Ｖq*を座標変換して、周波数指令値に対応した周波数を有する交流電圧指令値Ｖu*、Ｖv*、Ｖw*を生成し、これに基づいてインバータを可変速制御している。なお、通常のベクトル制御では電動機の磁束に平行な成分をｄ軸、垂直な成分をｑ軸と定義している。
【０００３】
ここで、ｄ軸電圧指令値Ｖd*とｑ軸電圧指令値Ｖq*の理論式を数1と数2に示す。それらの式において、ｒ1は誘導電動機の一次抵抗、Ｍは相互インダクタンス、Ｌ2は二次側自己インダクタンス、Ｌσは漏れインダクタンス一次側換算値の和を示す。
【０００４】
【数１】

【０００５】
【数２】

ところで、実際のすべり周波数ωsは直接検出できないことから、例えば、数3に示す誘導電動機の検出電流に基づいた式により推定したすべり周波数推定値ωs’を用いている。同式中、ＩdFBはｄ軸検出電流値、ＩqFBはｑ軸検出電流値、Ｔ2は電動機の二次時定数である。
【０００６】
【数３】

したがって、周波数指令値ω1*は数４に示すように、速度指令値ωr*とすべり周波数推定値ωs’の和となる。
【０００７】
【数４】

一方、定常状態において誘導電動機に流れる励磁電流Ｉdとトルク電流Ｉq、及びｄ軸磁束Φ2dとｑ軸磁束Φ2qは、数５、数式６の関係を満たしている。なお、ωsは電動機の実際のすべり周波数である。
【０００８】
【数５】

【０００９】
【数６】

ここで、ベクトル制御では、Φ2d＞０、Φ2q＝０が常に満たされているものとして制御する。また、誘導電動機に発生するトルクτは、Φ2dとＩqの積に比例する。この誘導電動機の制御方法は、例えば総合電子出版社発行の「ACサーボシステムの理論と設計の実際（p102-p103）」に記載されている。
【００１０】
【発明が解決しようとする課題】
しかし、従来方式においては、誘導電動機の起動や加速時のように、電動機の発生トルクに対して負荷トルクが大きい場合には、過渡的に数５、数６の条件が崩れて磁束が変動し、トルクτが不足して起動失敗や加速失敗に至る場合がある。これは、起動時のように負荷トルクが大きいと、実際のすべり周波数ωsが急激に増加し、電流Ｉd、Ｉqがその変化に追従できない場合が生ずることによる。
【００１１】
すなわち、前述したように、ベクトル制御はΦ2q＝０、Φ2d＞０の条件が満たされているものとして制御理論が組み立てられている。しかし、数6のΦ2qの理論式には、実すべり周波数ωs（＝ω1*−実モータ速度）が負の項に含まれているため、起動時又は加速時に周波数指令値ω1*を急激に増加させることにより実すべり周波数ωsが増加すると、過渡的にΦ2qが定常時の“０”から負側（Φ2q＜0）になる。Φ2qが負になると、数5から明らかなように、Φ2dが減少する。その結果、トルクτ＝Φ2d×Ｉqが減少し、発生トルクがますます不足して起動及び加速できないという問題が出るのである。
【００１２】
そこで、本発明は、誘導電動機の起動時や加速時における過渡的な磁束低下を抑制し、十分なトルクを発生させることを課題とする。
【００１３】
【課題を解決するための手段】
本発明は、次に述べる手段により、上記課題を解決するものである。
【００１４】
本発明は、速度指令値にすべり周波数に相関する物理量の修正値を加算し、該修正された速度指令値に基づいて出力電圧の周波数を制御して誘導電動機をベクトル制御する誘導電動機駆動装置において、前記すべり周波数に相関する物理量に応じて前記修正値を低減補正することを特徴とする。
【００１５】
すなわち、負荷トルクが大きい場合に周波数指令を増加させると、実すべり周波数が増大するから、すべり周波数に相関する物理量の修正値が増大し、これにより益々周波数指令値が高くなる一方、電流Ｉd、Ｉqの制御がその変化に追従できないために、ますます発生トルクが不足することになる。
【００１６】
そこで、本発明は、少なくとも出力電圧の周波数制御に係る速度指令値に加算する修正値を、例えば、すべり周波数推定値よりも小さな値に低減補正することにより、周波数制御に係る速度指令値を実際の電動機速度に近付けて実すべり周波数を低減するようにしたのである。その結果、電流Ｉd、Ｉq制御の追従性が改善され、十分なトルクを発生させることができるのである。
【００１７】
ここで、修正値を補正する因子のすべり周波数に相関する物理量は、電動機電流と電動機の発生トルクと電動機電流に基づいて推定されるすべり周波数推定値の少なくとも１つを適用できる。この場合、すべり周波数に相関する物理量が設定値以上のときと、変化率の少なくとも一方に応じて修正値を低減補正することが好ましい。また、速度指令値が設定値以下のときに、修正値を低減補正するようにしてもよい。この場合、修正値の低減補正の度合いは、速度指令値が設定値以下のときに、速度指令値に応じて変えるようにすることができる。
【００１８】
ところで、上記のように低減補正すると、修正値は、同一トルク条件もしくは同一電動機電流条件下で、所定の電動機速度以下における値が該所定の電動機速度以上における値よりも小さくなる。
【００１９】
【発明の実施の形態】
以下、本発明の実施の形態について図を用いて説明する。
（第一実施形態）
本発明の第一の実施形態について、図1〜図３を用いて説明する。図２は、本発明に係る誘導電動機駆動装置の第一実施形態及び周辺部を含む全体構成図である。図１は、図２の交流電圧指令演算部２０の詳細構成図である。
【００２０】
図２に示すように、誘導電動機駆動装置は、交流電源1から供給される三相交流電圧を順変換器２で直流電圧に変換し、変換された直流電圧を平滑コンデンサ３で平滑し、平滑された直流電圧を逆変換器４により所望の周波数の三相交流電圧に変換して誘導電動機６に供給するようになっている。逆変換器４は、例えばＩＧＢＴなどの半導体スイッチ素子を用いて構成され、それらの半導体スイッチ素子はＰＷＭゲートパルス演算部１１で生成されたゲート信号によって制御される。ＰＷＭゲートパルス演算部１１へ入力される交流電圧指令値は、電流検出部５により検出された電動機電流と速度指令値ωr*に基づいて交流電圧指令演算部２０で演算により求められるようになっている。
【００２１】
次に、交流電圧指令演算部２０の詳細について述べる。第一実施形態は、誘導電動機の起動時や加速時等のように負荷トルクが大きい時に周は巣指令を増加させた場合に起きる過渡的なトルク不足を補償するため、位相θ及びｄ軸電圧指令値Ｖd*の演算に用いる周波数指令値ω1*を、すべり周波数推定値ωs’に相関させた小さな値より修正することを特徴とする。つまり、周波数指令値自体を低減すると共に、数5、数６で説明したように、実すべり周波数ωsが大きくなるとΦ2dが減少するので、その減少を抑えるためである。
【００２２】
一方、ｑ軸電圧指令値Vq*の演算に用いるすべり周波数推定値ωs’は、従来同様に、例えば数３により求めた値とすることを特徴とする。その理由は、Vq*=ω1*×Φ2qであるから、すべり周波数推定値ωs’を小さく補正すると、ω1*が小さくなってVq*が低下し、Iqが下がって、却ってトルクが減少してしまうからである。
【００２３】
図1において、図示していない制御器等から入力される速度指令値ωr*は、加算器２１、２２に入力されている。すべり周波数演算部２３は、電動機電流Ｉmをｄｑ軸座標変換して得られるＩdFBとIqFBを入力し、数３に基づいてすべり周波数推定値ωs’を演算して出力するように構成されている。なお、ＩdFB、ＩqFBは検出値に代えて制御部内で生成される電流指令値Ｉd*、Iq*を用いることも、よく知られている。また、ＩdFB、ＩqFBは図示していない座標変換部により、電動機電流Ｉmをｄｑ軸座標系に変換して得られることもよく知られている。
【００２４】
すべり周波数補正部２４は、すべり周波数演算部２３から出力されるすべり周波数推定値ωs’を入力し、これに係数ｋ（ただし、０≦ｋ＜１）を掛けてすべり周波数補正値ｋ・ωs’を出力する。つまり、加算器２１に入力されるすべり周波数補正値ｋ・ωs’は、加算器２２に入力されるすべり周波数推定値ωs’に比例し、かつすべり周波数推定値ωs’よりも小さい値である。また、すべり周波数推定値ωs’とすべり周波数補正値ｋ・ωs’は、図３に示すすべり周波数演算部２３とすべり周波数補正部２４において、電動機電流に基づいてそれぞれ独立に求めるようにしてもよい。
【００２５】
加算器２１と加算器２２は、速度指令値ωr*にすべり周波数を加算して修正する部分である。加算器２１は、出力（ωr*＋ｋ・ωs’）を周波数指令値ω1*Cとして位相演算部２５に、また周波数指令値ω1*BとしてＶd*演算部２６に入力する。また、加算器２２は、出力（ωr*＋ωs’）を周波数指令値ω1*AとしてＶq*演算部２７に入力する。Ｖd*演算部２６は、入力される励磁電流指令値Ｉd*とトルク電流指令値Ｉq*及び周波数指令値ω1*Bを用いて、ｄ軸電圧指令値Ｖd*を演算する。Ｖq*演算部２７は、励磁電流指令値Ｉd*とトルク電流指令Ｉq*及び周波数指令値ω1*A を用いて、ｑ軸電圧指令値Ｖq*を演算する。位相演算部２５においては、周波数指令値ω1*C を積分して位相θを演算する。座標変換部２８は、ｄ軸電圧指令値Ｖd*とｑ軸電圧指令値Ｖq*を位相θに従って座標変換を行い、周波数指令値ω1*Cに対応する周波数の交流電圧指令値Ｖu*、Ｖv*、Ｖw*を生成し、図1のＰＷＭゲートパルス演算部１１に出力する。
【００２６】
次に、本実施形態の動作を説明する。ここで、位相θを演算する際の周波数指令値ω1*Cと、Ｖd*の演算に用いる周波数指令値ω1*Bは、何れも加算器２１の出力（ωr*＋ｋ・ωs’）であるから本来同一値であるが、理論式の理解を助けるために、便宜的に両者を区別して表している。本実施形態のＶd*、Ｖq*は、数７〜数９の様になり、電動機電流Ｉd、Ｉqは数１０〜１２の様になる。なお、ｒσは電動機抵抗の一次側換算値の和である。
【００２７】
【数７】

【００２８】
【数８】

【００２９】
【数９】

【００３０】
【数１０】

【００３１】
【数１１】

【００３２】
【数１２】

本実施形態のように、ω1*B＝ω1*C＜ω1*Aに設定することにより、電動機の実すべり周波数ωsは、数１３のように、すべり周波数推定値ωs’に比べて小さめに制御される。その結果、数式５、数式６におけるωsの増加に伴う磁束Φ2dの急減を抑えることができる。
【００３３】
【数１３】

特に、Ｖq*演算用の周波数指令値ω1*Aは、数８から判るように、数式３に従いすべり周波数推定値ωs’をそのまま用いている。したがって、Ｖq*は低下しない。これは、電圧指令値Ｖq*の低下に伴う磁束Φ2ｑの低下を起こさせないようにして、トルクの減少を抑えるためである。
【００３４】
ところで、Vd*演算用の周波数指令値ω1*Bを、位相θ演算用の周波数指令値ω1*Cと同一にしたのは、仮に、ω1*B＞ω1*Cにすると、数７のＶd*を数１０に代入して明らかなように、Ｉdが低下して磁束及びトルクが減少するからである。そこで、本実施形態では、ω1*B＝ω1*Cに設定することにより、Ｉdの低下を抑えて磁束Φ2ｄの低減を抑制しているのである。
【００３５】
このように、本実施形態は、インバータを制御する周波数指令値ω1*Cを小さな値に補正し、周波数指令値ω1*Cを電動機の実回転速度に近付けて、実すべり周波数の急激な増加に起因する過渡的な磁束低下を抑制して、十分なトルクを発生させることを本旨とする。
【００３６】
また、周波数指令値ω1*Cに合わせてd軸電圧指令値Ｖd*を制御する周波数指令値ω1*Bを小さな値に補正することが好ましい。これによれば、（ω1*C−ω1*B）の要素を含むd軸励磁電流Ｉdの低下を抑えてトルクの低下を抑えることができる。
【００３７】
更に、ｑ軸電圧指令値Ｖq*の制御に用いる周波数指令値ω1*Aは、周波数指令値ω1*Cよりも大きな値にすることが好ましい。例えば、すべり周波数推定値を基準にして制御することにより、ｑ軸電流Ｉqの低下を抑えてトルクの低下を抑えることができる。
【００３８】
ここで、図４を用いて、本実施形態による検証結果を説明する。図4は、本実施形態を用いた場合と従来方式の場合の電動機起動特性のシミュレーション結果を示す。従来方式においては、周波数指令を増加させた場合、磁束が低下してトルク電流が許容値以上に流れているにも拘わらず、トルクは起動トルクにも達していない。これに対し、本発明方式においては、周波数指令増加後に磁束は一旦下がるものの、直ぐに増加し、トルク電流が許容値以下で起動トルクが発生している。このため、従来方式では起動失敗を起こし電動機速度はゼロのままだが、本発明方式によれば電動機の起動が達成されている。
（第二実施形態）
本発明の第二実施形態を図５〜図７を用いて説明する。本実施形態が図１の実施形態と異なる部分は、すべり周波数補正部２４に代えて、数9における係数ｋを速度指令値ωr*に応じて変化させるようにしたすべり周波数補正部３０を設けたことにある。その他については、第一実施形態と同一であることから、同一符号を付して説明を省略する。
【００３９】
つまり、図１の実施形態において、係数ｋを一定値に保持すると、電動機が起動又は加速して所定の速度に到達した場合でも、周波数指令値ω1*Aと周波数指令値ω1*Bが異なったままになり、定常状態において磁束の不安定要因となる。
【００４０】
そこで、本実施形態のすべり周波数補正部３０は、速度指令ωr*を取り込み、ωr*に応じて係数ｋを増加し、所定以上の速度において係数ｋを“１”に変更して、周波数指令値ω1*Aと周波数指令値ω1*Bを一致させるようにしている。すなわち、すべり周波数補正部３０は、例えば図６に示すように、速度指令ωr*が停止時からωr1*までは数９の係数kをk1（0≦k1＜1）に設定し、ωr1*からωr2*までは徐々に増加させて、ωr2*以上でk=1に変更するように設定する。例えば、ωr1*は定格速度の３~４％、ωr2*は定格速度の１０%程度に設定することができる。
【００４１】
なお、速度指令ωr*に応じて係数ｋを増加する方法は、図6に限らず図7のようにすることができる。つまり、ωr*がωr1*に到達した時間t1から所定の時間t2までの間はkをk1から1に徐々に変化させる。図6、図7のように、係数ｋを一定の増加率で緩やかに“１”に変化させる理由は、kを例えばステップ的に“１”に増加すると、過渡的なトルク変動を生じるからである。そこで、kを“１”に変化させる時間は、例えば電流が変化する場合の時定数Tσ（=Lσ／rσ）の1／10以上から、磁束が変化する場合の時定数Ｔ2の１０倍程度とするのが好ましい。（第三実施形態）
本発明の第三の実施形態を図8に示す。本実施形態が図５の実施形態と異なる点は、すべり周波数補正部３０の係数ｋを電動機電流に応じて変化させるようにした点にある。例えば、トルク電流Ｉqが所定値を超える場合、それは磁束が十分でないことが原因と考えられる。そこで、トルク電流Ｉqが所定値Ｉqrefを越えた場合、すべり周波数補正値ｋ・ωs’を更に小さくする。これにより、第一実施例で述べたように磁束Φ2dの低下を抑制して、Ｉqの増加を抑えることができる。ここで、Ｉqrefの設定値は、インバータに流すことができる許容電流値よりも低く設定する。この本実施形態によれば、電動機の起動又は加速時における過電流を抑制する効果もある。
【００４２】
上述した第二及び第三実施形態は、見方を変えると、すべり周波数推定値ωs’は、同一トルクもしくは同一電流の条件下では電動機速度に関わらず同一である。一方、すべり周波数補正値ｋ・ωs’は、同一トルクもしくは同一電流の条件下では、低速度領域と高速度領域で値が異なるように設定される。そして、電動機の起動又は加速時における磁束の低下を抑制して高トルクを得ることができる。特に、第二及び第三実施形態によれば、加速後の高速運転時においても安定した運転を行うことができる。
【００４３】
また、図５、図８の実施形態では、すべり周波数補正部２４の係数kを速度指令値又は電動機電流に応じて変化させるようにしたが、これに代えてすべり周波数補正部２４はすべり周波数推定値ωs’の急激な変化を抑えるように、例えばωs’の変化率を制限する要素を用いることができる。
（第四実施形態）
図９に、本発明の第四実施形態の交流電圧指令演算部の構成図を示す。本実施形態は第一実施形態に対して演算の手順が異なるだけであり、実質的に等価である。すなわち、Vq*演算部２７に入力する周波数指令を、Ｖd*演算部２６に入力する周波数指令ω1*Bと同じにする。そして、すべり周波数推定値ωs’からすべり周波数補正値ｋ・ωs’を減算する減算器３１を設け、この減算器３１の出力（１−ｋ）ωs’をVq*補正値演算部３２に入力する。Vq*補正値演算部３２は、数１４によりΔVq*を求めて加算器３３に出力してVq*演算部２７の出力の電圧指令値Ｖq*に加算してＶq*補正するようにしている。
【００４４】
つまり、Vd*演算部２６とVq*演算部２７は、各々数１、２に従って演算する。Vq*補正値演算部３２は、数１４にしたがってΔVq*を演算する。
【００４５】
【数１４】

（第四実施形態の変形例）
また、図９のすべり周波数補正部２４に代えて、図５又は図８のすべり周波数補正部３０を適用し、電動機速度が所定の速度に達した際に、係数kをωr*もしくは電動機電流に基づいて変化させることにより、第二又は第三実施形態と同様の効果が得られる。
【００４６】
ここで、第四実施形態及びその変形例について、見方を変えると、同一トルクもしくは同一電流の条件下において、低速度領域におけるVq*補正値ΔVq*を高速度領域での値より大きく設定して、電動機の起動又は加速時における磁束低下を抑制して高トルクを得ているということができる。また、第四実施形態の変形例によれば、加速後の高速運転時でも安定した運転を行うことができる。
（第五実施形態）
図１０に第五実施形態の特徴部の構成を示す。本実施形態のすべり周波数演算部３４は、トルク電流の検出値ＩqFBと、励磁電流の指令値Ｉd*とから、数１５に基づいて、すべり周波数推定値ωs’を演算する。数１５は数４のＩdFBを指令値Ｉd*に置き換えたものである。定常状態においてはＩdFB=Ｉd*となるから、数１５は数４と等価となる。
【００４７】
【数１５】

このようにして求めたすべり周波数推定値ωs’を、加算器２１で速度指令値ωr*に足して周波数指令値ω1*を演算する。Ｖd*演算部２６は数１に基づいてVd*を演算する。一方、本実施形態では、Ｖd*補正値演算部３５により、例えば数１６のようにVd*補正値ΔVd*を演算する。そして、加算器３６でΔVd*をVd*に足して、過渡トルク補償を実現している。
【００４８】
【数１６】

ここで、係数kを0≦k＜１とし、ΔVd*＞０とする。ΔVd*をVd*に足すことで演算された新しいVd*は、数式７、数式12に表されるVd*と等価となる。また、数１６のkを電動機が所定の速度に達した後、 kを1に変化させることは、図５、図８の実施形態と同様である。また、同一トルクもしくは同一電流の条件下において、低速度領域でのＶd*補正値を高速度領域での値より大きく設定する場合も同様であり、これにより第一及び第二実施形態と同様の効果が得られる。
【００４９】
なお、本実施形態では図示を省略したが、Ｖq*演算部２７及び位相演算部２５は、加算器２１から出力される周波数指令値ω1*に基づいて、それぞれＶq*及びθを演算する。
【００５０】
なお、ｋを変化させる場合は、急峻なトルクの変動を防止するため、例えば、電流が変化する場合の時定数Ｔσ（＝Ｌσ／ｒσ）の１／１０以上から、磁束が変化する場合の時定数Ｔ２の１０倍の時間でｋを0から１に変化させるようなレートで行なえばよい。
【００５１】
【発明の効果】
以上述べたように、本発明によれば、誘導電動機の起動時や加速時にも十分なトルクを発生させることができる。
【００５２】
また、ｄ軸電圧指令値の演算及び位相の演算に用いる周波数指令値を、電動機電流に応じて小さく修正するようにしたものによれば、起動時や加速時にも十分なトルクを発生させ、かつ過電流を抑制する効果がある。
【００５３】
また、ｄ軸電圧指令値の演算及び位相の演算に用いる周波数指令値を、速度指令値又は電動機電流に応じて補正して小さい値にしたものによれば、加速後の高速運転時においても安定して運転を行える効果がある。
【図面の簡単な説明】
【図１】本発明の誘導電動機駆動装置の特徴部に係る一実施の形態の交流電圧指令演算部の構成図である。
【図２】本発明の誘導電動機駆動装置に係る一実施の形態の全体構成図である。
【図３】図１のすべり周波数補正部の変形例を示す図である。
【図４】図１実施形態の効果を説明する動作波形図である。
【図５】本発明の誘導電動機駆動装置の特徴部に係る他の実施の形態の交流電圧指令演算部の構成図である。
【図６】図５実施形態のすべり周波数補正部の係数ｋの設定法を説明する図である。
【図７】図５実施形態のすべり周波数補正部の係数ｋの他の設定法を説明する図である。
【図８】本発明の誘導電動機駆動装置の特徴部に係る更に他の実施の形態の交流電圧指令演算部の構成図である。
【図９】本発明の誘導電動機駆動装置の特徴部に係る更に他の実施の形態の交流電圧指令演算部の構成図である。
【図１０】本発明の誘導電動機駆動装置の特徴部に係る更に他の実施の形態の交流電圧指令演算部に係る主要部の構成図である。
【符号の説明】
２０交流電圧指令演算手段
２１、２２加算器
２３すべり周波数演算部
２４すべり周波数補正部
２５位相演算部
２６Ｖd*演算部
２７Ｖq*演算部
２８座標変換部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a drive device that performs variable speed control of an induction motor by vector control, and specifically relates to a control technique during start-up or acceleration.
[0002]
[Prior art]
When the induction motor is controlled at a variable speed by vector control, the slip frequency ωs is added to the speed command value ωr * to obtain the inverter frequency command value ω1 *, and based on this, the d-axis voltage command value Vd * and the q-axis voltage are obtained. The command value Vq * and the phase θ are calculated, and the AC voltage supplied to the induction motor is vector-controlled to vary the speed. That is, Vd * and Vq * are coordinate-transformed by the phase θ corresponding to the frequency command value ω1 * to generate AC voltage command values Vu *, Vv * and Vw * having frequencies corresponding to the frequency command value. Based on the above, the inverter is controlled at a variable speed. In normal vector control, the component parallel to the magnetic flux of the motor is defined as the d-axis, and the component perpendicular to the q-axis is defined as the q-axis.
[0003]
Here, the theoretical expressions of the d-axis voltage command value Vd * and the q-axis voltage command value Vq * are shown in

Equations

1 and 2. In these equations, r1 is the primary resistance of the induction motor, M is the mutual inductance, L2 is the secondary side self-inductance, and Lσ is the sum of the leakage inductance primary side converted values.
[0004]
[Expression 1]

[0005]
[Expression 2]

Incidentally, since the actual slip frequency ωs cannot be directly detected, for example, the estimated slip frequency ωs ′ estimated by the equation based on the detected current of the induction motor shown in Equation 3 is used. In the equation, IdFB is a d-axis detection current value, IqFB is a q-axis detection current value, and T2 is a secondary time constant of the motor.
[0006]
[Equation 3]

Accordingly, the frequency command value ω1 * is the sum of the speed command value ωr * and the estimated slip frequency ωs ′ as shown in Equation 4.
[0007]
[Expression 4]

On the other hand, the excitation current Id and torque current Iq flowing through the induction motor in the steady state, and the d-axis magnetic flux Φ2d and q-axis magnetic flux Φ2q satisfy the relationship of Equation 5 and Formula 6. Note that ωs is the actual slip frequency of the motor.
[0008]
[Equation 5]

[0009]
[Formula 6]

Here, in the vector control, control is performed assuming that Φ2d> 0 and Φ2q = 0 are always satisfied. The torque τ generated in the induction motor is proportional to the product of Φ2d and Iq. This induction motor control method is described in, for example, “Theory and Design Practice of AC Servo Systems (p102-p103)” published by Soken Publishing Co., Ltd.
[0010]
[Problems to be solved by the invention]
However, in the conventional method, when the load torque is larger than the generated torque of the motor, such as when the induction motor is started or accelerated, the conditions of Equations 5 and 6 are transiently broken and the magnetic flux fluctuates. In some cases, the torque τ is insufficient, leading to a start failure or acceleration failure. This is because when the load torque is large as at the time of start-up, the actual slip frequency ωs increases rapidly and the currents Id and Iq may not be able to follow the change.
[0011]
That is, as described above, the control theory is assembled assuming that the vector control satisfies the conditions of Φ2q = 0 and Φ2d> 0. However, since the actual slip frequency ωs (= ω1 * -actual motor speed) is included in the negative term in the theoretical formula of Φ2q in Equation 6, the frequency command value ω1 * increases rapidly during startup or acceleration. When the actual slip frequency ωs increases, Φ2q transiently changes from “0” in the steady state to the negative side (Φ2q <0). When Φ2q becomes negative, Φ2d decreases as is clear from Equation 5. As a result, the torque τ = Φ2d × Iq decreases, and the problem arises that the generated torque becomes more and more insufficient and cannot be started up and accelerated.
[0012]
Therefore, an object of the present invention is to suppress a transient decrease in magnetic flux at the time of starting or accelerating the induction motor and generate a sufficient torque.
[0013]
[Means for Solving the Problems]
The present invention solves the above problems by the following means.
[0014]
The present invention relates to an induction motor driving device that adds a correction value of a physical quantity correlated with a slip frequency to a speed command value, and controls the frequency of an output voltage based on the corrected speed command value to perform vector control of the induction motor. The correction value is reduced and corrected in accordance with a physical quantity correlated with the slip frequency.
[0015]
That is, when the frequency command is increased when the load torque is large, the actual slip frequency increases, so that the correction value of the physical quantity correlated with the slip frequency increases, thereby increasing the frequency command value while the current Id, Since the control of Iq cannot follow the change, the generated torque becomes increasingly insufficient.
[0016]
Therefore, the present invention actually reduces the speed command value related to frequency control by reducing and correcting a correction value added to at least the speed command value related to frequency control of the output voltage, for example, to a value smaller than the estimated slip frequency value. The actual slip frequency was reduced by approaching the motor speed. As a result, the followability of the current Id and Iq control is improved, and sufficient torque can be generated.
[0017]
Here, at least one of the estimated slip frequency values estimated based on the motor current, the generated torque of the motor, and the motor current can be applied to the physical quantity correlated with the slip frequency as a factor for correcting the correction value. In this case, it is preferable to reduce and correct the correction value in accordance with at least one of the change rate and the physical quantity correlated with the slip frequency. Further, when the speed command value is equal to or less than the set value, the correction value may be corrected to be reduced. In this case, the degree of correction correction of the correction value can be changed according to the speed command value when the speed command value is equal to or less than the set value.
[0018]
By the way, when the reduction correction is performed as described above, the correction value becomes smaller than a value above the predetermined motor speed when the value is lower than the predetermined motor speed under the same torque condition or the same motor current condition.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
A first embodiment of the present invention will be described with reference to FIGS. FIG. 2 is an overall configuration diagram including the first embodiment of the induction motor driving device according to the present invention and peripheral portions. FIG. 1 is a detailed configuration diagram of the AC voltage command calculation unit 20 of FIG.
[0020]
As shown in FIG. 2, the induction motor driving device converts the three-phase AC voltage supplied from the AC power source 1 into a DC voltage by the forward converter 2, and smoothes the converted DC voltage by the smoothing capacitor 3. The converted DC voltage is converted into a three-phase AC voltage having a desired frequency by the inverse converter 4 and supplied to the induction motor 6. The inverse converter 4 is configured using semiconductor switch elements such as IGBTs, for example, and these semiconductor switch elements are controlled by a gate signal generated by the PWM gate pulse calculation unit 11. The AC voltage command value input to the PWM gate pulse calculation unit 11 is calculated by the AC voltage command calculation unit 20 based on the motor current detected by the current detection unit 5 and the speed command value ωr *. Yes.
[0021]
Next, details of the AC voltage command calculation unit 20 will be described. In the first embodiment, the phase θ and the d-axis voltage are used to compensate for the transient torque shortage that occurs when the nest command is increased when the load torque is large, such as when the induction motor is started or accelerated. The frequency command value ω1 * used for the calculation of the command value Vd * is corrected from a small value correlated with the slip frequency estimated value ωs ′. In other words, the frequency command value itself is reduced, and as described in the equations 5 and 6, as the actual slip frequency ωs increases, Φ2d decreases, so that the decrease is suppressed.
[0022]
On the other hand, the slip frequency estimated value ωs ′ used for the calculation of the q-axis voltage command value Vq * is a value obtained by, for example, Equation 3 as in the conventional case. The reason is that Vq * = ω1 * × Φ2q, so if the slip frequency estimation value ωs' is corrected to a small value, ω1 * decreases, Vq * decreases, Iq decreases, and torque decreases instead. Because.
[0023]
In FIG. 1, a speed command value ωr * input from a controller or the like (not shown) is input to

adders

21 and 22. The slip frequency calculation unit 23 is configured to input IdFB and IqFB obtained by converting the motor current Im by dq axis coordinates, calculate the slip frequency estimated value ωs ′ based on Equation 3, and output it. It is well known that IdFB and IqFB use current command values Id * and Iq * generated in the control unit instead of the detected values. It is also well known that IdFB and IqFB are obtained by converting the motor current Im into a dq axis coordinate system by a coordinate conversion unit (not shown).
[0024]
The slip frequency correction unit 24 receives the slip frequency estimation value ωs ′ output from the slip frequency calculation unit 23, and multiplies the estimated slip frequency value ωs ′ by a coefficient k (where 0 ≦ k <1), thereby obtaining a slip frequency correction value k · ωs ′. Is output. That is, the slip frequency correction value k · ωs ′ input to the adder 21 is proportional to the slip frequency estimation value ωs ′ input to the adder 22 and is smaller than the slip frequency estimation value ωs ′. Further, the slip frequency estimated value ωs ′ and the slip frequency correction value k · ωs ′ may be obtained independently from each other based on the motor current in the slip frequency calculation unit 23 and the slip frequency correction unit 24 shown in FIG. .
[0025]
The adder 21 and the adder 22 are parts that are corrected by adding the slip frequency to the speed command value ωr *. The adder 21 inputs the output (ωr * + k · ωs ′) as a frequency command value ω1 * C to the phase calculation unit 25 and as a frequency command value ω1 * B to the Vd * calculation unit 26. Further, the adder 22 inputs the output (ωr * + ωs ′) as the frequency command value ω1 * A to the Vq * calculation unit 27. The Vd * calculation unit 26 calculates the d-axis voltage command value Vd * using the input excitation current command value Id *, torque current command value Iq *, and frequency command value ω1 * B. The Vq * calculation unit 27 calculates the q-axis voltage command value Vq * using the excitation current command value Id *, the torque current command Iq *, and the frequency command value ω1 * A. The phase calculation unit 25 calculates the phase θ by integrating the frequency command value ω1 * C. The coordinate conversion unit 28 performs coordinate conversion of the d-axis voltage command value Vd * and the q-axis voltage command value Vq * according to the phase θ, and the AC voltage command values Vu * and Vv * of the frequency corresponding to the frequency command value ω1 * C. , Vw * are generated and output to the PWM gate pulse calculator 11 of FIG.
[0026]
Next, the operation of this embodiment will be described. Here, the frequency command value ω1 * C for calculating the phase θ and the frequency command value ω1 * B used for calculating Vd * are both outputs (ωr * + k · ωs ′) of the adder 21. Although they are essentially the same value, they are shown separately for convenience in order to help understand the theoretical formula. In this embodiment, Vd * and Vq * are as shown in Equations 7 to 9, and the motor currents Id and Iq are as shown in Equations 10 to 12. Rσ is the sum of the primary side converted values of the motor resistance.
[0027]
[Expression 7]

[0028]
[Equation 8]

[0029]
[Equation 9]

[0030]
[Expression 10]

[0031]
[Expression 11]

[0032]
[Expression 12]

By setting ω1 * B = ω1 * C <ω1 * A as in the present embodiment, the actual slip frequency ωs of the motor is controlled to be smaller than the estimated slip frequency ωs ′ as shown in Equation 13. Is done. As a result, it is possible to suppress a sudden decrease in the magnetic flux Φ2d accompanying the increase in ωs in Equations 5 and 6.
[0033]
[Formula 13]

In particular, the frequency command value ω1 * A for Vq * calculation uses the slip frequency estimated value ωs ′ as it is according to Equation 3, as can be seen from Equation 8. Therefore, Vq * does not decrease. This is to prevent a decrease in torque without causing a decrease in magnetic flux Φ2q accompanying a decrease in voltage command value Vq *.
[0034]
By the way, the frequency command value ω1 * B for Vd * calculation is made the same as the frequency command value ω1 * C for phase θ calculation. If ω1 * B> ω1 * C, then Vd * This is because Id is lowered and magnetic flux and torque are reduced as is apparent by substituting. Therefore, in this embodiment, by setting ω1 * B = ω1 * C, the decrease in Id is suppressed and the decrease in magnetic flux Φ2d is suppressed.
[0035]
As described above, in this embodiment, the frequency command value ω1 * C for controlling the inverter is corrected to a small value, and the frequency command value ω1 * C is brought close to the actual rotational speed of the motor, so that the actual slip frequency is increased rapidly. The main purpose is to generate a sufficient torque while suppressing the transitional magnetic flux drop caused by the phenomenon.
[0036]
Further, it is preferable to correct the frequency command value ω1 * B for controlling the d-axis voltage command value Vd * to a small value in accordance with the frequency command value ω1 * C. According to this, it is possible to suppress a decrease in torque by suppressing a decrease in d-axis excitation current Id including the element (ω1 * C−ω1 * B).
[0037]
Furthermore, it is preferable that the frequency command value ω1 * A used for controlling the q-axis voltage command value Vq * is larger than the frequency command value ω1 * C. For example, by controlling on the basis of the estimated slip frequency value, it is possible to suppress a decrease in torque by suppressing a decrease in the q-axis current Iq.
[0038]
Here, the verification result according to the present embodiment will be described with reference to FIG. FIG. 4 shows the simulation results of the motor starting characteristics when this embodiment is used and when the conventional method is used. In the conventional method, when the frequency command is increased, the torque does not reach the starting torque even though the magnetic flux decreases and the torque current flows above the allowable value. On the other hand, in the method of the present invention, the magnetic flux once decreases after the frequency command increases, but increases immediately, and the starting torque is generated when the torque current is below the allowable value. For this reason, in the conventional method, starting failure occurs and the motor speed remains zero, but the starting of the motor is achieved according to the method of the present invention.
(Second embodiment)
A second embodiment of the present invention will be described with reference to FIGS. The present embodiment differs from the embodiment of FIG. 1 in that a slip frequency correction unit 30 is provided in which the coefficient k in Equation 9 is changed according to the speed command value ωr * instead of the slip frequency correction unit 24. There is. Since others are the same as those in the first embodiment, the same reference numerals are given and description thereof is omitted.
[0039]
That is, in the embodiment of FIG. 1, when the coefficient k is held at a constant value, the frequency command value ω1 * A and the frequency command value ω1 * B differ even when the motor starts or accelerates and reaches a predetermined speed. It becomes an unstable factor of the magnetic flux in the steady state.
[0040]
Therefore, the slip frequency correction unit 30 of the present embodiment takes in the speed command ωr *, increases the coefficient k according to ωr *, changes the coefficient k to “1” at a speed equal to or higher than a predetermined value, and sets the frequency command value ω1 * A and the frequency command value ω1 * B are made to coincide. That is, for example, as shown in FIG. 6, the slip frequency correction unit 30 sets the coefficient k of Equation 9 to k1 (0 ≦ k1 <1) from the time when the speed command ωr * is stopped to ωr1 *, and from ωr1 * It is set to gradually increase up to ωr2 * and change to k = 1 at ωr2 * or more. For example, ωr1 * can be set to 3 to 4% of the rated speed, and ωr2 * can be set to about 10% of the rated speed.
[0041]
Note that the method of increasing the coefficient k in accordance with the speed command ωr * is not limited to FIG. 6 and can be as shown in FIG. That is, k is gradually changed from k1 to 1 from time t1 when ωr * reaches ωr1 * to a predetermined time t2. As shown in FIGS. 6 and 7, the reason why the coefficient k is gradually changed to “1” at a constant increase rate is that when k is increased to “1” stepwise, for example, a transient torque fluctuation occurs. is there. Therefore, the time for changing k to “1” is, for example, from 1/10 or more of the time constant Tσ (= Lσ / rσ) when the current changes to about 10 times the time constant T2 when the magnetic flux changes. It is preferable to do this. (Third embodiment)
A third embodiment of the present invention is shown in FIG. The present embodiment is different from the embodiment of FIG. 5 in that the coefficient k of the slip frequency correction unit 30 is changed according to the motor current. For example, when the torque current Iq exceeds a predetermined value, it is considered that the magnetic flux is not sufficient. Therefore, when the torque current Iq exceeds the predetermined value Iqref, the slip frequency correction value k · ωs ′ is further reduced. Thereby, as described in the first embodiment, a decrease in the magnetic flux Φ2d can be suppressed, and an increase in Iq can be suppressed. Here, the set value of Iqref is set lower than the allowable current value that can be passed through the inverter. According to this embodiment, there is also an effect of suppressing an overcurrent at the time of starting or accelerating the electric motor.
[0042]
From the viewpoint of the second and third embodiments described above, the slip frequency estimated value ωs ′ is the same regardless of the motor speed under the condition of the same torque or the same current. On the other hand, the slip frequency correction value k · ωs ′ is set so that the value is different between the low speed region and the high speed region under the same torque or current condition. And the high torque can be obtained by suppressing the decrease of the magnetic flux at the time of starting or accelerating the electric motor. In particular, according to the second and third embodiments, stable operation can be performed even during high-speed operation after acceleration.
[0043]
In the embodiment of FIGS. 5 and 8, the coefficient k of the slip frequency correction unit 24 is changed according to the speed command value or the motor current. Instead, the slip frequency correction unit 24 estimates the slip frequency. For example, an element that limits the rate of change of ωs ′ can be used so as to suppress a rapid change in the value ωs ′.
(Fourth embodiment)
In FIG. 9, the block diagram of the alternating voltage command calculating part of 4th embodiment of this invention is shown. This embodiment is substantially equivalent to the first embodiment except for the calculation procedure. That is, the frequency command input to the Vq * calculation unit 27 is the same as the frequency command ω1 * B input to the Vd * calculation unit 26. Then, a subtractor 31 for subtracting the slip frequency correction value k · ωs ′ from the slip frequency estimated value ωs ′ is provided, and the output (1-k) ωs ′ of the subtractor 31 is input to the Vq * correction value calculation unit 32. . The Vq * correction value calculation unit 32 obtains ΔVq * by Equation 14 and outputs it to the adder 33 to add to the voltage command value Vq * output from the Vq * calculation unit 27 to correct Vq *.
[0044]
That is, the Vd * computing unit 26 and the Vq * computing unit 27 perform computations according to

Equations

1 and 2, respectively. The Vq * correction value calculation unit 32 calculates ΔVq * according to Equation 14.
[0045]
[Expression 14]

(Modification of the fourth embodiment)
Further, instead of the slip frequency correction unit 24 of FIG. 9, the slip frequency correction unit 30 of FIG. 5 or FIG. 8 is applied, and when the motor speed reaches a predetermined speed, the coefficient k is changed to ωr * or the motor current. The effect similar to 2nd or 3rd embodiment is acquired by making it change based.
[0046]
Here, in terms of the fourth embodiment and its modifications, the Vq * correction value ΔVq * in the low speed region is set larger than the value in the high speed region under the same torque or current conditions. In other words, it can be said that high torque is obtained by suppressing the decrease in magnetic flux at the start-up or acceleration of the motor. Further, according to the modification of the fourth embodiment, stable operation can be performed even during high-speed operation after acceleration.
(Fifth embodiment)
FIG. 10 shows the configuration of the characteristic part of the fifth embodiment. The slip frequency calculation unit 34 according to the present embodiment calculates a slip frequency estimated value ωs ′ from the torque current detection value IqFB and the excitation current command value Id * based on Equation 15. Equation 15 is obtained by replacing IdFB in Equation 4 with a command value Id *. Since IdFB = Id * in the steady state, Equation 15 is equivalent to Equation 4.
[0047]
[Expression 15]

The frequency command value ω1 * is calculated by adding the estimated slip frequency value ωs ′ thus obtained to the speed command value ωr * by the adder 21. The Vd * calculation unit 26 calculates Vd * based on Equation 1. On the other hand, in the present embodiment, the Vd * correction value calculator 35 calculates the Vd * correction value ΔVd * as shown in Equation 16, for example. The adder 36 adds ΔVd * to Vd * to realize transient torque compensation.
[0048]
[Expression 16]

Here, the coefficient k is set to 0 ≦ k <1 and ΔVd *> 0. The new Vd * calculated by adding ΔVd * to Vd * is equivalent to Vd * expressed by Equation 7 and Equation 12. Further, after the motor reaches a predetermined speed, k in Equation 16 is changed to 1 as in the embodiment of FIGS. The same applies to the case where the Vd * correction value in the low speed region is set to be larger than the value in the high speed region under the same torque or the same current, which is the same as in the first and second embodiments. An effect is obtained.
[0049]
Although not shown in the present embodiment, the Vq * calculator 27 and the phase calculator 25 calculate Vq * and θ, respectively, based on the frequency command value ω1 * output from the adder 21.
[0050]
When k is changed, in order to prevent steep torque fluctuation, for example, when the magnetic flux changes from 1/10 or more of the time constant Tσ (= Lσ / rσ) when the current changes. What is necessary is just to carry out at the rate which changes k from 0 to 1 in the time 10 times the constant T2.
[0051]
【The invention's effect】
As described above, according to the present invention, a sufficient torque can be generated even when the induction motor is started or accelerated.
[0052]
Further, according to the frequency command value used for the calculation of the d-axis voltage command value and the phase calculation, the torque command value is corrected to be small according to the motor current, and sufficient torque is generated at the time of start-up and acceleration, and There is an effect of suppressing overcurrent.
[0053]
In addition, the frequency command value used for the calculation of the d-axis voltage command value and the phase calculation is corrected according to the speed command value or the motor current to a small value, so that it is stable even during high-speed operation after acceleration. And has the effect of being able to drive.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an AC voltage command calculation unit according to an embodiment of a feature of an induction motor drive device of the present invention.
FIG. 2 is an overall configuration diagram of an embodiment according to an induction motor driving device of the present invention.
FIG. 3 is a diagram showing a modification of the slip frequency correction unit in FIG. 1;
FIG. 4 is an operation waveform diagram for explaining the effect of the embodiment in FIG. 1;
FIG. 5 is a configuration diagram of an AC voltage command calculation unit of another embodiment according to the characteristic part of the induction motor drive device of the present invention.
6 is a diagram illustrating a method for setting a coefficient k of a slip frequency correction unit according to the embodiment in FIG. 5;
7 is a diagram for explaining another setting method of the coefficient k of the slip frequency correction unit in the embodiment of FIG. 5;
FIG. 8 is a configuration diagram of an AC voltage command calculation unit of still another embodiment relating to the characteristic part of the induction motor drive device of the present invention.
FIG. 9 is a configuration diagram of an AC voltage command calculation unit of still another embodiment relating to the characteristic part of the induction motor drive device of the present invention.
FIG. 10 is a configuration diagram of a main part relating to an AC voltage command calculating part of still another embodiment relating to the characteristic part of the induction motor driving device of the present invention;
[Explanation of symbols]
20 AC voltage command calculation means 21, 22 Adder 23 Slip frequency calculation unit 24 Slip frequency correction unit 25 Phase calculation unit 26 Vd * calculation unit 27 Vq * calculation unit 28 Coordinate conversion unit

Claims

In the induction motor drive device that adds a physical quantity correlated with the slip frequency to the speed command value as a correction value, and controls the frequency of the output voltage based on the corrected speed command value to vector control the induction motor.
The correction value is corrected by reducing the correction value so as to increase the torque in the rotational direction, the frequency of the output voltage is controlled based on the speed command value corresponding to the correction value corrected by the reduction correction, and the correction before the correction of the reduction An induction motor drive device that controls the magnitude of the output voltage based on the speed command value.

2. The induction motor drive device according to claim 1, wherein the physical quantity correlated with the slip frequency is at least one of a slip frequency estimated value estimated based on a motor current, a motor generated torque, and the motor current. .

The induction motor drive device according to claim 1, wherein the correction value is reduced and corrected according to at least one of a change rate and a physical quantity correlated with the slip frequency.

The induction motor drive device according to claim 1, wherein the correction value is reduced and corrected when the speed command value is equal to or less than a set value.

The induction motor drive device according to claim 4, wherein when the speed command value is equal to or less than a set value, the correction value is reduced and corrected according to the speed command value.

6. The correction value according to claim 1, wherein a value below a predetermined motor speed is smaller than a value above the predetermined motor speed under the same torque condition or the same motor current condition. Induction motor drive device.

In the induction motor drive device that adds a physical quantity correlated with the slip frequency to the speed command value as a correction value, and controls the frequency of the output voltage based on the corrected speed command value to vector control the induction motor.
Means for correcting the correction value according to at least one of the motor current and the motor speed is provided, and the correction value corrected below the predetermined motor speed by the means has a torque in the rotational direction under the same motor current condition. The frequency of the output voltage is controlled based on the speed command value according to the correction value corrected to be smaller than the value above the predetermined motor speed so as to increase, and the correction before the correction is made smaller An induction motor drive device that controls the magnitude of an output voltage based on a speed command value corresponding to the value.

8. The induction motor drive device according to claim 7, wherein the correction value correcting unit reduces and corrects the correction value according to at least one of the motor current and the motor speed change rate.

8. The induction motor drive apparatus according to claim 7, wherein the correction value correcting unit reduces and corrects the correction value according to a change rate of a predetermined time constant related to a characteristic parameter of the induction motor.

A physical quantity correlated with the slip frequency is added as a correction value to the speed command value, and an output voltage related to vector control is controlled according to the corrected speed command value, and the output based on the corrected speed command value In the induction motor drive device that controls the frequency of the voltage,
Means for correcting at least the correction value related to the speed command value for controlling the frequency of the output voltage according to at least one of a predetermined time constant related to a characteristic parameter of the induction motor, a motor speed, and a characteristic parameter of the induction motor is provided. The frequency of the output voltage is controlled according to the corrected value corrected for reduction, and the magnitude of the output voltage is controlled according to the corrected speed command value before the correction of the correction. Is an induction motor drive device characterized in that the frequency of the output voltage is reduced so as to increase the torque in the rotational direction.

The means for correcting the correction value reduces and corrects the correction value according to at least one rate of change of a predetermined time constant relating to the motor current, the motor speed, and the characteristic parameter of the induction motor. The induction motor drive device according to claim 10.

11. The means for correcting the correction value corrects the speed command value related to the control of the d-axis voltage of the output voltage by the same correction value as the correction value related to the control of the frequency. Or the induction motor drive device of 11.

The means for correcting the correction value changes the correction value according to at least one of a predetermined time constant relating to a motor current, a motor speed, and a characteristic parameter of the induction motor. The induction motor drive device described.

The correction value corrected by the means for correcting the correction value is characterized in that, under the same torque condition or the same motor current condition, a value below a predetermined motor speed is smaller than a value above the predetermined motor speed. The induction motor drive device according to any one of claims 10 to 12.

A physical quantity correlated to the slip frequency is added as a correction value to the speed command value, and the d-axis output voltage and the q-axis output voltage related to vector control are controlled according to the corrected speed command value, and the corrected speed In the induction motor drive device that controls the frequency of the output voltage based on a command value,
The q-axis output voltage is a value corresponding to the corrected speed command value, the d-axis output voltage is smaller than a value corresponding to the corrected speed command value, and the frequency of the output voltage is the rotational direction An induction motor drive device, wherein the torque is corrected and controlled to be smaller than a value corresponding to the corrected speed command value so as to increase the torque of the induction motor.

A physical quantity correlated with the slip frequency is added as a correction value to the speed command value, and an output voltage related to vector control is controlled according to the corrected speed command value, and the output based on the corrected speed command value In the induction motor drive device that controls the frequency of the voltage,
According to at least one of a predetermined time constant relating to a motor current, a motor speed, and a characteristic parameter of the induction motor, the frequency command value of the output voltage is reduced and corrected so as to increase the torque in the rotation direction, and the reduction Based on the corrected frequency command, a q-axis voltage command value and a d-axis voltage command value of the output voltage are obtained, and further, the obtained q-axis voltage command value is corrected to be increased and controlled using each command value. An induction motor drive device comprising means for performing

The means for correcting the q-axis voltage command value corrects the corrected q-axis voltage command value largely below the predetermined motor speed compared to the predetermined motor speed or higher under the same torque condition or the same motor current condition. The induction motor drive device according to claim 16.

The means for correcting the q-axis voltage command value changes the correction amount of the q-axis voltage command value in accordance with at least one rate of change of the motor current, the motor speed, and the time constant. The induction motor drive device according to claim 17.

The frequency command value is generated by adding the slip frequency estimated value obtained based on the motor current to the speed command value, and the voltage command value related to vector control is generated based on the frequency command value and the frequency of the output voltage is controlled. In the induction motor drive device,
A frequency command value A that generates a slip frequency compensation value smaller than the estimated slip frequency value, adds the estimated slip frequency value to the speed command value, and a frequency command that adds the slip frequency compensation value to the speed command value A value B is generated, a q-axis voltage command value is calculated using the frequency command value A, a d-axis voltage command value is calculated using the frequency command value B, and an output voltage is calculated using the frequency command value B. The frequency command value is set as a value that reduces and corrects the frequency of the output voltage to increase the torque in the rotational direction.

The induction motor drive device according to claim 19, wherein a d-axis voltage command value is calculated using the frequency command value B.

The induction motor drive device according to claim 19 or 20, wherein a difference obtained by subtracting the frequency command value B from the frequency command value A is greater than 0 times and less than or equal to 1 times a rated slip angular frequency.

The induction motor drive device according to claim 19, wherein when the speed command value or the motor speed reaches a set value or more, the frequency command value A and the frequency command value B are matched.

23. When matching the frequency command value A and the frequency command value B, both values are changed at a rate of change of a predetermined time constant related to a characteristic parameter of the induction motor. Induction motor drive device.

The time required to make the frequency command value A and the frequency command value B coincide with each other is 1 of Tσ of the induction motor (the sum Lσ of the primary-side converted value of the leakage inductance / the sum rσ of the primary-side converted value of the motor resistance). 24. The induction motor drive device according to claim 23, wherein the induction motor drive time is 10 times or less of a secondary time constant T2 of the induction motor.

23. The induction motor drive device according to claim 22, wherein when the frequency command value A and the frequency command value B are matched, the difference between the two is changed according to the rate of change of the speed command value. .

The induction motor drive device according to claim 19, wherein when the motor current exceeds a set value, a difference between the frequency command value A and the frequency command value B is increased.

27. The induction motor drive device according to claim 26, wherein the slip frequency compensation value is decreased to increase the difference between the frequency command value A and the frequency command value B.

The induction motor drive device according to claim 19, wherein the slip frequency compensation value is set to 0 when the motor current exceeds a set value.

29. The induction motor drive according to claim 28, wherein when the slip frequency compensation value is set to 0, the slip frequency compensation value is changed at a rate of change of a predetermined time constant related to a characteristic parameter of the induction motor. apparatus.

The time required to make the slip frequency compensation value 0 is 1/10 or more of the Tσ of the induction motor (the sum Lσ of the primary side conversion value of the leakage inductance / the sum rσ of the primary side conversion value of the motor resistance), 30. The induction motor drive device according to claim 29, wherein the induction motor drive device is 10 times or less of a secondary time constant T2 of the induction motor.

29. The induction motor drive device according to claim 28, wherein when the slip frequency compensation value is set to 0, the slip frequency compensation value is set to zero according to a rate of change of the speed command value.

After the induction motor is activated, the voltage magnitude and frequency of the induction motor are controlled based on the frequency command value. At the time of activation, the change in the frequency with respect to the change in the voltage magnitude after the voltage application is activated. The voltage magnitude is controlled based on the frequency command value so as to be smaller than the frequency change with respect to the voltage magnitude change after that, and the frequency of the voltage is set to a value according to the frequency command value. An induction motor control device characterized by performing reduction control .

The induction motor control device according to claim 32, wherein a change in frequency with respect to a change in the magnitude of the voltage is controlled based on an output current.

After the induction motor is started, the current magnitude and frequency of the induction motor are controlled based on the frequency command value. At the time of start-up, the change in frequency relative to the change in the current magnitude after the current is generated is started. The current magnitude is controlled based on the frequency command value so as to be smaller than the frequency change with respect to the current magnitude change , and the current frequency is set to a value according to the frequency command value. An induction motor control device characterized by performing reduction control .

The induction motor control device according to claim 34, wherein a change in frequency with respect to a change in the magnitude of the current is controlled based on an output current.

After the induction motor is activated, the voltage magnitude and frequency of the induction motor are controlled based on the frequency command value. At the time of activation, the change in the frequency with respect to the change in the voltage magnitude after the voltage application is activated. The voltage magnitude is controlled based on the frequency command value so as to be smaller than the frequency change with respect to the voltage magnitude change after that, and the frequency of the voltage is set to a value according to the frequency command value. Induction motor control method that also reduces control .

The induction motor control method according to claim 36, wherein a change in frequency with respect to a change in the magnitude of the voltage is controlled based on an output current.

After the induction motor is started, the current magnitude and frequency of the induction motor are controlled based on the frequency command value. At the time of start-up, the change in frequency relative to the change in the current magnitude after the current is generated is started. The current magnitude is controlled based on the frequency command value so as to be smaller than the frequency change with respect to the current magnitude change , and the current frequency is set to a value according to the frequency command value. Induction motor control method that also reduces control .

39. The induction motor control method according to claim 38, wherein a change in frequency with respect to a change in the magnitude of the current is controlled based on an output current.

An induction motor control device that calculates a frequency command value and calculates a voltage command value based on the frequency command value , and after being activated, controls the frequency of the voltage of the induction motor based on the calculated frequency command value Then, the magnitude of the voltage of the induction motor is controlled by the voltage command value, and at the time of start-up, the voltage of the induction motor is controlled based on the calculated voltage command value after voltage application, and the torque in the rotational direction is controlled. calculating a corrected frequency command value smaller than the frequency command value is the basis of computation of the voltage command value to increase, and the control means controls the frequency of the voltage by the small corrected frequency command value induction motor control apparatus for.

An induction motor control device that calculates a frequency command value and controls the magnitude and frequency of a current based on the frequency command value . After being activated, the frequency of the current of the induction motor is calculated based on the calculated frequency command value. And the magnitude of the current of the induction motor is controlled according to the command value, and when starting up, the magnitude of the current is controlled to increase the torque in the rotational direction after the current is generated. An induction motor control device that calculates a frequency command value corrected to be smaller than the frequency command value and controls a current frequency by the frequency command value corrected to be smaller .

An induction motor control method for calculating a frequency command value and calculating a voltage command value based on the frequency command value , wherein after being started, the frequency frequency of the induction motor is controlled by the calculated frequency command value Then, the magnitude of the voltage of the induction motor is controlled by the voltage command value, and at the time of start-up, the voltage of the induction motor is controlled based on the calculated voltage command value after voltage application, and the torque in the rotational direction is controlled. An induction motor control method for calculating a frequency command value corrected to be smaller than a frequency command value that is a basis of calculation of the voltage command value so as to increase, and controlling a frequency of the voltage by the frequency command value corrected to be small .

An induction motor control method for calculating a frequency command value and controlling the magnitude and frequency of a current based on the frequency command value , wherein after being started, the frequency of the current of the induction motor is calculated based on the calculated frequency command value. controls to control the magnitude of the current of the induction motor in accordance with the finger command value, at the time of activation, so to increase the torque in the rotational direction, after the current generation, and the control of the magnitude of the current An induction motor control method for calculating a frequency command value corrected to be smaller than the frequency command value and controlling a current frequency by the frequency command value corrected to be smaller .

An induction motor control device that calculates a frequency command value by adding a physical quantity correlated with a slip frequency to a speed command value, and controls a voltage frequency and a voltage based on the frequency command value after startup. The frequency of the induction motor voltage is controlled based on the frequency command value calculated by reducing the sliding speed so as to increase the torque in the rotational direction, and from the voltage corresponding to the frequency command value found to be small An induction motor control device characterized by controlling the voltage so as to be a large value.

An induction motor control device that calculates a frequency command value by adding a physical quantity correlated with a slip frequency to a speed command value, and controls a current frequency and a current based on the frequency command value after startup. The frequency of the induction motor current is controlled based on the frequency command value calculated by reducing the sliding speed so as to increase the torque in the rotational direction, and from the current corresponding to the frequency command value that is found to be small An induction motor control device that controls the current so as to be a large value.

An induction motor control method for calculating a frequency command value by adding a physical quantity correlated with a slip frequency to a speed command value, and controlling a voltage frequency and controlling a voltage based on the frequency command value after startup. The frequency of the induction motor voltage is controlled based on the frequency command value calculated by reducing the sliding speed so as to increase the torque in the rotational direction, and from the voltage corresponding to the frequency command value found to be small Induction motor control method for controlling the voltage so as to be a large value.

An induction motor control method for calculating a frequency command value by adding a physical quantity correlated with a slip frequency to a speed command value, and controlling a current frequency and controlling a current based on the frequency command value after startup. The frequency of the induction motor current is controlled based on the frequency command value calculated by reducing the sliding speed so as to increase the torque in the rotational direction, and from the current corresponding to the frequency command value that is found to be small Induction motor control method for controlling the current so that the current becomes a large value.

Calculates a frequency command value, said calculating a voltage command value based on the frequency command value, after startup, an induction motor control apparatus for controlling an induction motor based on said frequency command value and voltage command value, starting in controls the magnitude of the voltage of the induction motor using the voltage command value, as to increase the torque in the rotational direction, the frequency command value is smaller than the frequency command value corresponding to the voltage command value An induction motor control device that calculates and controls the frequency of the voltage of the induction motor using the calculated frequency command value .

An induction motor control device that calculates a frequency command value and controls a current frequency of the induction motor based on the frequency command value after startup and controls a current of the induction motor based on the frequency command value. In starting, the frequency command value smaller than the frequency command value corresponding to the current is calculated so as to increase the torque in the rotation direction while controlling the current , and the calculated frequency command value is used. And controlling the frequency of the current of the induction motor.

A frequency command value is calculated by adding a physical quantity correlated with a slip frequency to the speed command value, a voltage command value is calculated based on the frequency command value, and after startup , based on the frequency command value and the voltage command value An induction motor control method for controlling an induction motor, wherein the voltage command value is used for startup and a frequency smaller than a frequency command value corresponding to the voltage command value so as to increase a torque in the rotation direction. induction motor control method that controls an induction motor by using a command value.

The frequency command value is calculated by adding a physical quantity correlated with the slip frequency to the speed command value.After startup, the frequency is controlled based on the frequency command value, and the current of the induction motor is calculated based on the frequency command value. An induction motor control method for controlling, in starting, is controlled by using the frequency command value that is smaller than the frequency command value corresponding to the current so that the current is controlled and the torque in the rotation direction is increased. induction motor control method that controls an electric motor.

An induction motor that calculates a frequency command value by adding a physical quantity correlated with a slip frequency to a speed command value, and controls the frequency and magnitude of the voltage applied to the induction motor according to the frequency command value after startup. In the control device, at the time of activation, a change in frequency with respect to a change in the magnitude of the voltage after voltage application is smaller than a change in frequency with respect to a change in the magnitude of the voltage after activation. In addition, the induction motor control device is characterized in that the frequency of the applied voltage is corrected and controlled so that the frequency is lower than the frequency corresponding to the command value used for controlling the magnitude of the voltage .

An induction motor that calculates a frequency command value by adding a physical quantity correlated with a slip frequency to a speed command value, and controls the frequency and magnitude of the current applied to the induction motor according to the frequency command value after startup. In the control device, at the time of start-up, the ratio that is the ratio of the change in frequency to the change in the magnitude of the current after the generation of current is higher than the ratio of the rated slip frequency to the magnitude of the rated current of the induction motor. Induction motor control characterized in that the frequency of the applied current is corrected and controlled so that the frequency is lower than the frequency corresponding to the command value used for controlling the magnitude of the current so as to be smaller apparatus.

A frequency command value is calculated, and after starting, an induction motor control method for controlling the frequency and the magnitude of the voltage applied to the induction motor according to the frequency command value . The command value used for controlling the voltage magnitude is set so that the frequency change with respect to the voltage magnitude change is smaller than the frequency change with respect to the voltage magnitude change after activation. induction motor control method that controls to correct the frequency of the corresponding voltage the applied such that the reduced frequency than the frequency.

A frequency command value is calculated, and after startup, an induction motor control method for controlling the frequency and magnitude of current applied to the induction motor according to the frequency command value . , the rate of change in frequency with respect to a change in magnitude is the ratio of the current, rather than the ratio of the change in the rated slip frequency for the magnitude of the rated current of the induction motor, so that small, control of the magnitude of the current induction motor control method that controls to modify the frequency of the current the applied such that the frequencies lower than a frequency corresponding to a command value used for.

An induction motor control device that controls the frequency and magnitude of a current applied to an induction motor, and controls the current frequency of the induction motor based on a frequency command value after startup and corresponds to the frequency command value. and by controlling the magnitude of the current of the induction motor, at the time of startup, after the current generation, the ratio is the ratio of change in frequency with respect to changes in the magnitude of the current rating for the magnitude of the rated current of the induction motor The magnitude of the current is controlled by the frequency command value so as to be smaller than the ratio of the change in the slip frequency, and the current frequency is controlled based on the value reduced from the command value used for controlling the magnitude of the current. An induction motor control device characterized by:

An induction motor control method for controlling the frequency and magnitude of a current applied to an induction motor, wherein after starting, the current frequency of the induction motor is controlled based on the frequency command value, and the frequency command value is and by controlling the magnitude of the current of the induction motor, at the time of startup, after the current generation, the ratio is the ratio of change in frequency with respect to changes in the magnitude of the current rating for the magnitude of the rated current of the induction motor The magnitude of the current is controlled by the frequency command value so as to be smaller than the ratio of the change in the slip frequency, and the current frequency is controlled based on the value reduced from the command value used for controlling the magnitude of the current. induction motor control method.