JP5088414B2 - Disturbance suppression device and disturbance suppression method for electric motor - Google Patents

Description

【数２】

【００５１】
数式２で示されるフーリエ係数Ｔ_An、Ｔ_Bnは、電動機回転数および周期的外乱である脈動成分が任意期間で一定であれば直流値を出力することに着目する。仮に何らかの制御を与えてこれらの係数がどちらも０で定常となれば、その周波数成分のトルク脈動は抑圧されたことを意味する。
【００５２】
そこで、本発明では、任意の脈動周波数成分ごとにフーリエ変換を施し、２つのフーリエ係数が０となるように周期性外乱オブザーバ補償器を構成し、補償電流をベクトル制御インバータの電流指令値に重畳する。以下、図２を用いて本発明に係る外乱抑圧の基本的な構成を説明する。
【００５３】
図２は、図１のシステム構成を基に制御ブロックを展開している。指令値変換部１１は、トルク指令値Ｔ_refから、ベクトル制御における回転ｄｑ座標系のｄ軸およびｑ軸電流指令値Ｉ_do、Ｉ_qoに変換し（例えば、最大トルク制御）、電流指令値にトルク脈動補償電流を重畳してトルク脈動を抑圧する。図２の例ではｑ軸電流指令値に補償電流ｉ_qcを重畳しているが、ｄ軸電流、あるいはｄ軸とｑ軸の両方に与えても良い。あるいは、ｄｑ軸電流の干渉が問題にならないシステムであれば、トルク指令値に対して直接的にトルク脈動補償信号を重畳しても良い。なお、インバータ１２は３相から回転座標変換したｄ軸、ｑ軸において電流ベクトル制御を実現する一般的な電動機駆動装置であり、電動機負荷１３を駆動する。
【００５４】
正弦・余弦波生成器１４では、電動機負荷１３の回転子位相角θと、抑圧したい脈動成分の次数ｎを設定し、基準となる周波数の正弦・余弦波を生成する。フーリエ変換部１５では、この正弦・余弦波および任意のフーリエ変換周期Ｔ_rを設定して、軸トルク検出値Ｔ_detを数式２に基づきフーリエ変換し、ｎ次のフーリエ係数Ｔ_An、Ｔ_Bnを演算する。ここで、数式２のフーリエ変換の積分処理を適度な時定数を持つ低周波数域通過フィルタ（ローパスフィルタ）に置き換えることも可能である。
【００５５】
次に、脈動成分のフーリエ係数Ｔ_An、Ｔ_Bnが０（すなわち脈動を抑圧）となるように周期性外乱オブザーバ補償器１６を構成する。この部分の詳細は後述の実施形態で説明する。周期性外乱オブザーバ補償器１６の出力Ｉ_An、Ｉ_Bnは補償電流信号のフーリエ係数とし、乗算器１７Ａ，１７Ｂでｎ次の正弦・余弦波をそれぞれ乗算して逆変換する。つまり、時間波形の補償電流信号として復元する。復元した脈動補償電流ｉｑｃ^*は加算器によってベクトル制御インバータ７のｑ軸電流指令値ｉｑ０^*に重畳する。
【００５６】
なお、前述したとおり、軸トルク脈動を直接検出するのではなく、インバータ電流や速度検出値からオブザーバ等で推定したトルクを用いてもよいし、加速度センサで電動機筐体フレーム振動などを検出し、振動抑制を行うことも同様に考えられる。
【００５７】
本発明では核となる制御手法の説明を簡便にするため、トルクを軸トルクメータ等で直接検出した場合を例に挙げて、以下実施形態を説明する。
【００５８】
（実施形態１）
本実施形態では、電動機駆動システムの周波数特性を予め把握することから始める。周波数特性の把握やシステム同定を行う手法は多種多様であるが、これらは既知の一般的技術であるため、本発明では特定の手法に限定しない。例えば、図３のように、システム同定装置１８は、任意の定常動作状態において、白色雑音信号をトルク脈動補償電流として実システムに入力し、電流指令値に重畳する（図３はｑ軸電流に重畳しているが、ｄ軸、あるいはその両方でも良い）。そのときの軸トルク検出値をシステム出力信号として、システムの入出力データを得る。その入出力の時系列データから周波数応答をスペクトル解析し、脈動補償電流指令値から軸トルク検出値までの周波数伝達関数を入手することができる。システム同定理論に基づいて定式化することもできるし、物理モデル（例えば２慣性系モデル）に基づいてパラメータを求めることもできるが、本実施形態では数式３に示すように、周波数伝達関数を複素ベクトルの集合で表現する。集合の要素は各周波数成分におけるゲイン・位相特性を示す複素ベクトルに対応する。
【数３】

ただし、Ｐｓｙｓ＾：同定システム、ｍ：周波数成分の分割要素番号、Ｐ_Am：ｍ番目の要素の同定システム実数部、Ｐ_Bm：ｍ番目の要素の同定システム虚数部
【００５９】
ここで、分割要素番号ｍについて説明する。例えば同定に必要な周波数成分を直流〜５ｋＨｚ、分解能を１Ｈｚとすると、要素数は５００１個となる。したがって、ｍ＝｛０、１、２、３、…、４９９９、５０００｝として、各要素（周波数成分）には、スペクトル解析結果あるいはシステム同定結果を当てはめる。周波数成分毎のシステムのゲイン・位相特性は、複素平面の複素ベクトルで表現できるため、数式３のごとく表現することができる。
【００６０】
フーリエ変換を用いると任意周波数成分のトルク脈動をフーリエ係数で抽出することができる。数式２に示したように、２つのフーリエ係数は直交性を有するので、任意の周波数成分のシステム状態のみに着目して上述の数式３の複素ベクトルの１要素を抽出すると、その実部と虚部を２つのフーリエ係数に照らし合わせることができると考える。すなわち、ここでは実部を余弦フーリエ係数、虚部を正弦フーリエ係数に適合させる（例えば、反時計方向を遅れ位相と定義し、Ｐ_Bmの極性を反転させて適合させる）。
【００６１】
以上から、フーリエ変換後の任意周波数成分のみに着目すれば、システム特性を意味する数式３の複素ベクトルを用いて、その周波数成分の周期性外乱（トルク脈動）と、それを抑制するための脈動補償電流信号のフーリエ係数、およびトルク脈動検出値の関係が把握できる。また、これらの関係はフーリエ変換によってすべて直流成分で表されるので、周期性外乱もその周波数においては直流値となる。
【００６２】
ここで、図４のように、任意の１つの周波数成分のみを考慮した外乱抑圧制御系を考え、周期性外乱を推定・補償するための周期性外乱オブザーバ補償器を構成する。すなわち、軸トルク脈動検出値から数式４の逆システム（複素ベクトルの逆数）を介して補償電流指令値との誤差を求め、その誤差が周期性外乱に相当する周期性外乱電流であるとみなして、外乱を打ち消すように誤差補償分を補償電流指令値として重畳する。
【数４】

【００６３】
図４について説明する。実システム１９の特性Ｐ_sys（ｎ次成分）は数式４と同様に、ある周波数成分では１次元複素ベクトルで表されると考える。その入力には補償電流ｉ_qcnが与えられ、周期性外乱トルクＴ_rplnを打ち消すように脈動補償トルクＴ_cnを発生させる。トルク脈動はフーリエ変換によって抽出されるため、フーリエ変換部２０の応答伝達関数Ｇ_FTを介してトルク脈動検出値のフーリエ係数Ｔ_An、Ｔ_Bnを得る。これらは、複素ベクトルＴ_An＋Ｔ_Bnｉに置き換える。
【００６４】
次に、ｎ次外乱オブザーバ２１は、数式４の同定した周波数伝達関数の逆数（外乱は含まず）を用いて、外乱電流を含んだ電流入力情報を得て、そこから補償電流指令値を差し引くことで、周期性外乱電流ｄＩ_An、ｄＩ_Bnを推定する。Ｇ_OBSは、任意のフィルタ（例えば低域通過フィルタ）を挿入して、フーリエ変換抽出時の残留脈動や外乱推定誤差の影響を抑制し、脈動補償を安定化するために用いる。
【００６５】
上記のように周期性外乱を推定し、目標値（周期性外乱を抑圧する場合は通常０）から外乱相当の電流ｄＩ_An、ｄＩ_Bnを差し引いて、補償電流ｉ_qcnを生成する。
【００６６】
図５は、本実施形態を適用した場合の外乱抑圧効果を示している。波形は上から、軸トルク検出値［Ｎｍ］、トルク脈動フーリエ係数［Ｎｍ］、補償電流フーリエ係数［Ａ］、トルク脈動振幅評価値［Ｎｍ］である。例として１２次脈動成分のみを示している。
【００６７】
軸トルク波形を見ると、抑圧開始前は定常トルクに対してトルク脈動が大きく現れているが、抑圧後は脈動が大幅に低減されていることが分かる。トルク脈動の正弦／余弦フーリエ係数も抑圧後は０となっていることがわかる。
【００６８】
（実施形態２）
本実施形態では、図４におけるｎ次外乱オブザーバ２１のフィルタを指令値側と検出値側で分離する。本実施形態の構成例を図６に示す。
【００６９】
例えば、フーリエ変換による脈動抽出や通信・演算遅れ時間などを考慮して、Ｇ_OBS、Ｇ_LPFのフィルタ特性を別個に設定することも可能である。
【００７０】
本実施形態によれば、周期性外乱オブザーバの指令値側と検出値側のフィルタ特性を別々に設定し、検出系の遅れ等を考慮した外乱抑圧特性が得られる。
【００７１】
（実施形態３）
本実施形態では、電動機の回転速度が変化した場合を考慮して、電動機の回転速度検出値（あるいは推定値）を用いてフーリエ変換周期と外乱オブザーバフィルタのカットオフ周波数をともに可変とする。図７は、本実施形態の構成例である。
【００７２】
回転速度が変化すると数式３の複素ベクトル集合から引き出して適用する１つの要素（１次元複素ベクトル）も変化するので、速度に適応して（Ｐ_sys）^-1も可変とする。また、回転速度に応じてオブザーバフィルタＧ_OBSのカットオフ周波数とフーリエ変換応答Ｇ_FTも可変とし、常に安定した脈動抑圧効果が得られるように適応させる。
【００７３】
本実施形態によれば、回転速度変動にも逐次適応して周期性外乱を抑圧することができる。
【００７４】
（実施形態４）
フーリエ変換などを用いて周波数成分を抽出すると、その抽出時間がある期間必要となり、十分な外乱抑圧応答速度が得られないことがある。例えば、その応答を超える可変速運転や準定常トルク変動にも対応しようとした場合、抑圧効果が不十分になることが考えられる。
【００７５】
そこで、本実施形態では、上述までの周期性外乱抑圧手段を用いてトルク脈動を抑制した後に、その任意動作点の定常状態で脈動補償電流のフーリエ係数の２つをメモリに記録する。予めこのようなメモリ記録処理を各動作点で同様に行い、回転速度とトルク指令値を入力とした補償電流フーリエ係数テーブルを作成しておく。テーブルの代わりに、回転速度とトルク指令値をパラメータとした近似関数を用いてもよい。補償テーブルを生成した後は、動作点に応じてテーブルから補償電流フーリエ係数２つを読み出し、フィードフォワードで脈動補償電流を生成・適用する。
【００７６】
図８は、本実施形態の構成例である。図２と異なる部分は、回転子位相角θから回転速度演算部２２で回転速度Ｗ_mを求め、これとトルク指令値Ｔ_refから、補償テーブル２３（または補償近似関数）によって補償電流フーリエ係数Ｉ_An，Ｉ_Bnを読み出す。
【００７７】
本実施形態によれば、脈動補償電流のフーリエ係数を予め学習しておき、その係数を読み出す作業のみで抑圧できるので、回転数やトルク等の動作点の急激な変化にも瞬時に対応することが可能となる。
【００７８】
（実施形態５）
本実施形態は、実施形態４に加え、電動機の温度を検出して、温度変化によるシステム特性の変化を検出して、実施形態４と同様に各動作点でテーブル化、あるいは近似関数化しておく。
【００７９】
図９は、本実施形態の構成例である。図８と異なる部分は、電動機負荷１３の温度ｔを計測し、この温度ｔを補償テーブル２３の補償パラメータとして組み込む。
【００８０】
本実施形態によれば、温度依存性の強いシステムにも対応することができる。
【００８１】
（実施形態６）
本実施形態では、軸トルク検出をフィードバックした周期性外乱抑圧制御と、学習済みの補償テーブル（あるいは近似式）によるフィードフォワード補償方式を切り換えて使用する。制御を切り換える基準として、回転速度やトルク指令値を用いる。
【００８２】
例えば、回転数あるいはトルク指令値の変化率を見て、フーリエ変換応答以上の指令値変化率を入力する場合は、補償テーブルによる方式に切り換える。変化率が小さい準定常的な運転では、常時フィードバックによる周期性外乱抑圧手段を用いる。
【００８３】
フィードフォワードによる補償手段は、適用するシステムによってはシステム特性の摂動変化に十分対応できない場合があるので、上述のように運転状態を判別して切り換える手段を用いることにより、フィードフォワード運転を必要最小限にすることができる。
【００８４】
（実施形態７）
以上までの実施形態は、任意のひとつの脈動周波数成分についての周期性外乱抑圧制御手段であったが、各実施形態での構成を並列化すれば複数の周期性外乱の周波数成分を抑圧することが可能となる。
【００８５】
本実施形態の構成図を図１０に示し、２４₁〜２４_nはフーリエ級数の１次〜ｎ次の次数別に脈動成分を抑圧する制御要素になり、これらによる補償電流信号ｉ_qc1〜ｉ_qcnを加算器２５で互いに重畳させ、トルク脈動補償信号ｉ_qcとする。
本実施形態によれば、複数のトルク脈動を同時に抑制することができる。また、これらは同時に並列で抑制することができるので、ある周波数成分の外乱抑圧が、別の周波数成分の周期性外乱に悪影響を与える場合にも有効な手段となる。
【００８６】
（実施形態８）
上述までの実施形態では、軸トルクをフィードバックする構成を基にトルク脈動補償方式または方法を提案したが、フィードバックする対象を変更することも可能である。
【００８７】
本実施形態では、図１１のように、加速度センサ８によって電動機のフレーム・筐体の振動を検出してフィードバックする構成とする。外乱抑圧制御方法については、上述までの実施形態と同様である。
【００８８】
本実施形態によれば、電動機の筐体外乱を抑圧することができる。
【００８９】
（実施形態９）
本実施形態では、図１２のように、回転位置センサ６から提供される位相・速度情報の変動を検出して、その変動を抑制するように制御する。制御内容は基本的に上述までの実施形態と同様である。
【００９０】
本実施形態によれば、周期的な速度変動や位相変動を抑圧することができる。
【００９１】
（実施形態１０）
本実施形態では、図１３のように、インバータ７から脈動補償対象の電動機１に電源供給する３相ラインの電流を電流センサ９で検出し、電流外乱を抑圧する。
本実施形態によれば、インバータ電流検出値を用いてインバータ電流外乱を抑圧する、あるいはインバータ電流から換算したトルク推定値を用いて、推定外乱トルク脈動を抑圧することができる。
【００９２】
（実施形態１１）
前記までの実施形態によるトルクリプル抑制制御では、任意の脈動周波数成分ごとにフーリエ変換を施し、２つのフーリエ係数が０となるように周期性外乱オブザーバを構成することで全周波数帯域で安定した制御を得る「オンライン補償方式」とする。このオンライン補償方式によれば、可変速・負荷変動を有するシステムに対しても常時オンラインフィードバックでトルクリプルを抑制することができる。また、１次元複素ベクトルで表現したシステム同定結果を用いて、周期性外乱オブザーバモデルを自動調整する機能を持っているので、多慣性共振系システムへの実装もできる。
［００９３］
また、「オンライン補償方式」では、常に学習しているため、電動機やインバータ特性の経時変化にも対応可能となる。しかし、常に学習アルゴリズムの動作が必要のため、演算負荷が比較的高い、電動機の負荷装置を変更する場合もシステムの再同定が必要、学習時間が必要なため可変速運転やトルク変化への即応性で劣る、などで問題がある。
［００９４］
本実施形態１１および後に示す実施形態１２〜１４は、電動機やインバータの経時変化等にも対応可能にしたオンライン補償によるトルクリプル抑制ができ、しかも演算負荷軽減とシステムの再同定不要および即応性を有したトルクリプル抑制ができる制御装置および方法を提案するものである。
［００９５］
図１４は、本実施形態による電動機のトルク制御装置のブロック構成を示し、電流ベクトル制御方式のインバータの制御に、オンライン補償方式でトルクリプル抑制を行なう場合を示す。
［００９６］
図１４において、インバータ７の電流ベクトル制御部３１は、電流センサ３２で検出するモータ駆動電流ｉ_ｕ，ｉ_ｖ，ｉ_ｗとモータ１のロータ回転角度θから座標変換部３３によりモータ回転座標に同期したｄｑ軸直交回転座標系の電流に変換したｄ，ｑ軸電流検出値との比較によりモータ電流の制御を行う。ロータ回転角度θは回転位置センサ６によるエンコーダ波形ａｂｚから速度・位相検出部３４により速度ωと共に求められる。
［００９７］
トルク／ｉｄ，ｉｑ変換部３５（指令値変換部１１）は、コントローラ５からのトルク指令値Ｔ_ｒｅｆとモータ回転速度ωから、ベクトル制御における回転ｄｑ座標系のｄ軸およびｑ軸電流指令値ｉ_ｄ ^＊（Ｉ_ｄｏ）、ｉ_ｑ０ ^＊（Ｉ_ｑｏ）に変換し、これら電流指令値のうちｑ軸電流指令値ｉ_ｑ０ ^＊にトルク脈動補償電流ｉ_ｑｃｍを重畳して電流ベクトル制御指令値とする。
［００９８］
コントローラ５は、図１と同様に、トルクリプル抑制制御手段を搭載し、このトルクリプル抑制制御手段としては例えば図２に示す正弦・余弦波生成器１４とフーリエ変換部１５と周期性外乱オブザーバ補償器１６および乗算器１７Ａ，１７Ｂによって脈動成分のフーリエ係数Ｔ_Ａｎ、Ｔ_Ｂｎが０となるようなトルクリプル補償電流を求め、このトルクリプル補償電流ｉ_ｑｃ ^＊はベクトル制御インバータ７のｑ軸電流指令値ｉ_ｑ０ ^＊への補償信号にする。
［００９９］
ここで、本実施形態では「オンライン補償方式」を基本として、予め学習しておいた補償テーブルを併用して、フィードフォワード的に抑制する補償電流生成手段を追加する。この補償電流生成手段として振幅・位相補償テーブル３６と補償電流生成部３７を備える。
［０１００］
振幅・位相補償テーブル３６は、コントローラ５によってトルクリプル抑制制御を実行したときに指定した定常動作状態（定常トルク指令・定常回転数）で学習したトルクリプル補償電流ｉ_ｑｃ ^＊の振幅Ｍおよび位相φを記録する。この作業を複数の定常動作点で同様に記録して、トルク指令Ｔ_ｒｅｆ ^＊と回転数ωを変数とした２次元の振幅テーブルおよび位相テーブルを生成する。データ間の情報は線形補間等で補間する。
［０１０１］
補償電流生成部３７は、運転状態（トルク指令・回転数）からそのときの振幅Ｍと位相φを振幅／位相補償テーブル３６から読み出し、これら読み出した振幅Ｍと位相φは、そのときの回転位相θを用いて、テーブル補償電流ｉ_ｑｃｔ ^＊＝Ｍ・ｓｉｎ（ｎθ＋φ）を生成する（ｎは補償次数）。この生成したテーブル補償電流ｉ_ｑｃｔ ^＊は、オンライン補償電流ｉ_ｑ０ ^＊と合成してｑ軸電流指令値ｉ_ｑｃｍ ^＊とする。
したがって、テーブル補償電流ｉ_ｑｃｔ ^＊は、学習済みの補償電流テーブルから瞬時に振幅・位相を得て補償電流を生成するので、速度変化やトルク変化が起きた場合にも好適な補償電流を迅速に出力することができる。また、周辺温度の変化や経時的な物性変化などにより、トルクリプルが学習した時点の特性からずれてしまった場合にも、オンライン補償のフィードバックループが働いているので、テーブル補償電流の誤差を補正できる。
［０１０２］
（実施形態１２）
図１５は、本実施形態による電動機のトルク制御装置のブロック構成を示し、基本的な構成および作用は図１４と変わらないが、補償テーブル３６で発生する補償電流の振幅Ｍ・位相φの誤差を補正するように、コントローラ５からオンライン補償フィードバックループを構成する。
【０１０３】
図１５において、Ｍ^*は補償電流振幅指令値（オンライン補償分）、φ^*は補償電流位相指令値（オンライン補償分）であり、合成器３８，３９ではこれらを補償電流の振幅Ｍ・位相φにそれぞれ合成して補償電流生成部３７への補償電流振幅値（合成値）Ｍ’、補償電流位相値（合成値）φ’とする。
【０１０４】
実施形態１１では、補償電流生成後にテーブル補償電流ｉ_qct ^*とオンライン補償電流ｉ_qc ^*を合成していたが、本実施形態では振幅・位相の状態で合成する。すなわち、補償テーブル振幅値Ｍ、および補償テーブル位相値φを、それぞれオンライン補償振幅値Ｍ^*とオンライン補償位相値φ^*と合成して、合成補償電流振幅値Ｍ’、合成補償電流位相値φ’を生成する。補償電流生成部３７では、ｉ_qc ^*＝Ｍ’・ｓｉｎ（ｎθ＋φ’）にて、最終的な補償電流ｉ_qc ^*を生成する。（ｎは補償次数）
【０１０５】
本実施形態によれば、振幅・位相という直感的にわかりやすい状態量でテーブル誤差を把握・補正できるとともに、補償電流生成部３７を一カ所に纏めることができる。
【０１０６】
（実施形態１３）
図１６は本実施形態による電動機のトルク制御装置のブロック構成を示し、実施形態１２（図１５）の補償テーブル振幅Ｍ・位相φに代えて、余弦フーリエ係数および正弦フーリエ係数に置き換えた構成である。
【０１０７】
補償テーブル４０は、トルク指令Ｔ_ref ^*と回転速度ωに応じて補償電流余弦フーリエ係数テーブル値Ａと補償電流正弦フーリエ係数テーブル値Ｂを発生し、コントローラ５はオンライン補償電流余弦フーリエ係数Ａ^*とオンライン補償電流正弦フーリエ係数Ｂ^*を発生し、合成器３８，３９ではこれらを合成して補償電流余弦フーリエ係数合成値Ａ’と補償電流正弦フーリエ係数合成値Ｂ’を得る。
【０１０８】
トルクリプル抑制制御機能を搭載したコントローラ５では、基本的にフーリエ変換（あるいはそれに類する手法）によってトルクリプル周波数成分を抽出して抑制する手法を用いている。図２では、２つのフーリエ係数に相当する複素ベクトルの実部と虚部の成分があり、これらを用いて補償電流の振幅値、位相値を計算している。
【０１０９】
図２の構成では、周期性外乱オブザーバ補償器１６で生成された補償電流の実部成分をＢ（Ｉ_Bn）、虚部成分をＡ（Ｉ_An）として定義している。これらから、振幅Ｍおよび位相φは以下のように求められる。
【０１１０】
Ｍ＝√（Ａ²＋Ｂ²）、φ＝ｔａｎ^-1（Ｂ／Ａ）
【０１１１】
実施形態１１、１２は、上記の振幅Ｍ、および位相φを求めてから補償テーブル生成あるいはオンライン補償を行っており、補償電流の特性が直感的に分かりやすい反面、上述の演算変換が必要となっていた。
【０１１２】
そこで、本実施形態では、図１６に示すとおり、振幅・位相に変換する前の２つのフーリエ係数Ａ、Ｂの状態で補償テーブルを生成するとともに、オンライン補償についてもフーリエ係数の状態で合成して、最終段で補償電流ｉ_qc ^*を生成する。これにより、振幅・位相に変換する上記の演算の手間が省け、補償処理を簡略化できる。
【０１１３】
（実施形態１４）
本実施形態では、実施形態１１〜１３のいずれかの構成を並列化して同時に複数次数成分のトルクリプルを抑制する手法を提供する。
【０１１４】
例えば、実施形態１１の構成を並列化した場合について図１７に示す。（他の実施形態についても同様であるので、図面での説明は省略する。）図１７は、２つの補償テーブル３６Ａ、３６Ｂでは２つの次数成分で個別に振幅Ｍ、位相φを生成し、これらから２つの補償電流生成部３７Ａ，３７Ｂで２つの次数について補償電流を生成し、これら２つの次数について同時にトルクリプルを抑制する。なお、当然ではあるが３つ以上の次数を同時に抑制する場合についても拡張可能である。
【０１１５】
以上のとおり、本発明によれば、任意の脈動周波数成分ごとにフーリエ変換を施し、２つのフーリエ係数が０となるように周期性外乱オブザーバ補償器を構成し、補償電流をベクトル制御インバータの電流指令値に重畳するようにしたため、複雑な電動機システムの外乱抑圧ができ、かつ、周期的なトルク脈動などを抑制した安定な制御ができる。
【０１１６】
さらに、「オンライン補償方式」を基本として、予め学習しておいた補償テーブルを併用して、フィードフォワード的に抑制する補償電流を生成するため、演算負荷軽減とシステムの再同定不要および即応性を有したトルクリプル抑制ができる。【Technical field】
[0001]
  The present invention relates to an apparatus and a disturbance suppressing method for suppressing torque pulsation (disturbance) generated in an electric motor in a torque control apparatus for an electric motor that drives a rotating machine.
[Background]
[0002]
  A rotating electric machine such as an electric motor has structural magnetic flux distortion and cogging torque, and therefore generates torque pulsation that contributes to vibration and noise according to the rotation. In addition, various factors such as the magnetic imperfection of the motor structure, the response / current error of the inverter power supply that drives it, and the characteristics of the mechanical system are complicatedly related. In addition, when a multi-inertia system is configured between the motor and the load, the mechanical resonance point and the torque pulsation frequency component coincide with each other, generating an excessive shaft torsion torque, which adversely affects operating characteristics and damages the system. There is a danger of.
[0003]
  In order to solve these problems, a disturbance suppression method using a disturbance observer has been considered for a long time. The torque pulsation is regarded as a disturbance, and the disturbance is estimated by, for example, a general minimum-dimensional observer method and added to the command value so as to suppress it. However, such a disturbance observer has a frequency band condition that can be suppressed, and the suppression effect generally decreases in a high frequency region.
[0004]
  In order to alleviate the problem of the disturbance observer described above, a control method has been proposed in which a disturbance observer compensator and repetitive control are used together to suppress periodic disturbances such as torque pulsation (see, for example, Patent Document 1). In this method, in a frequency band that cannot be sufficiently suppressed only by a disturbance observer compensator, a strong periodic disturbance is suppressed by repetitive control, and an aperiodic disturbance is suppressed by using a normal disturbance observer compensator.
[0005]
  Another technique is to reduce the harmonic current of the motor. Rotational coordinate transformation is performed that rotates at a frequency that is an integral multiple of the frequency of the fundamental wave component of the current flowing through the motor, and its harmonic current is extracted and suppressed to zero by the PI controller. At this time, a technique has been proposed in which the harmonic velocity electromotive force is regarded as a disturbance, a disturbance observer is configured and added to a command value, and the disturbance is suppressed (for example, see Patent Document 2).
[Prior art documents]
[Patent Literature]
[0006]
[Patent Document 1]
Japanese Patent Gazette No. 2566033
[Patent Document 2]
Japanese Patent Gazette No. 35582505
SUMMARY OF THE INVENTION
[Problems to be solved by the invention]
[0007]
  In Patent Document 1, a general repetitive controller is used in combination to alleviate the problem of disturbance observer. That is, paying attention to the fact that the torque pulsation of the motor has periodicity, periodic disturbances are repeatedly compensated by the controller, and other non-periodic disturbances are suppressed by using a normal disturbance observer. However, it is not guaranteed that repetitive control in a rotating electromechanical system having complicated mechanical characteristics is stable in the entire frequency band. Therefore, the compensation signal may be returned to cause a divergence phenomenon.
[0008]
  On the other hand, in Patent Document 2, a rotational coordinate transformation of a harmonic that rotates at an integral multiple of the fundamental wave component frequency of the current flowing through the motor is performed, and the harmonic current of that component is extracted and is zeroed by the PI controller. Oppressed. At this time, the harmonic electromotive force is regarded as a disturbance, and a disturbance observer for estimating the disturbance is configured and added to the current command value on the harmonic rotation coordinates to suppress the harmonic current. Although this method can suppress the harmonic current flowing in the motor, the torque pulsation cannot always be suppressed with high accuracy, and it does not cope with complicated electromechanical characteristics such as a multi-inertia system and an inverter response.
[0009]
  An object of the present invention is to provide a disturbance suppressing device and a disturbance suppressing method for an electric motor that can suppress disturbance of a complicated electric motor system and can perform stable control while suppressing periodic torque pulsation.
[0010]
  In order to solve the above-mentioned problems, the present invention performs a Fourier transform for each arbitrary pulsation frequency component, configures a periodic disturbance observer compensator so that two Fourier coefficients are 0, and compensates the compensation current with a vector control inverter. Is superposed on the current command value, and has the following configuration and method.
[0011]
  (1) The controller converts the command value of the electric motor into d and q-axis current command values of a rotating coordinate system in vector control, and controls the motor by current control of the inverter according to the current command values.
  The controller uses the frequency component extraction means of Fourier transform to calculate the nth-order Fourier coefficient T from the DC value of the periodic pulsation of the motor._An, T_BnAnd its Fourier coefficient T_An, T_BnPeriodic disturbance observer compensation which superimposes a compensation current on the d and q axis current command values so as to suppress the periodic disturbance by estimating a periodic disturbance on the nth-order frequency component with a periodic disturbance observer compensator The apparatus is provided with means for suppressing disturbance by means of a vessel.
[0012]
  (2) Complex vector P is obtained by system identification of the frequency characteristics of the control system comprising the inverter and the motor._Am, P_BmThe periodic disturbance observer compensator is expressed by a set of the complex vector P corresponding to an arbitrary frequency._Am, P_BmThe inverse system identification model input obtained from_An, T_BnAnd a means for estimating a periodic disturbance of the n-th order frequency component.
[0013]
  (3) The periodic disturbance observer compensator subtracts a compensation current command value from the estimated periodic disturbance to thereby generate a periodic disturbance current dI._An, DI_BnAnd the periodic disturbance current dI from the current command value_An, DI_BnThe disturbance observer filter that subtracts the periodic disturbance from the compensation current command value and the disturbance observer filter that extracts the estimated periodic disturbance have different characteristics.
[0014]
  (4) The present invention is characterized by comprising means for variably setting the characteristics of the periodic disturbance observer compensator and the Fourier transform unit in accordance with the rotational speed.
[0015]
  (5) In a steady operation state at an arbitrary frequency, the periodic disturbance observer compensator previously learns and records the Fourier coefficient of the pulsation compensation current at a plurality of operating points, and uses the rotational speed and torque as input parameters. A means for generating a table or an approximate function and providing a pulsation compensation current by feedforward control is provided.
[0016]
  (6) The compensation current Fourier coefficient table or approximate function includes a detected temperature value of the motor as a parameter.
[0017]
  (7) Periodic disturbance suppression by the feedforward control is performed only when the rotational speed or torque command value exceeds a certain rate of change, and switching to periodic disturbance suppression by feedback is performed during other steady or quasi-steady operation. It is characterized by.
[0018]
  (8) The periodic disturbance observer compensator is applied to each of different frequency components, and parallelizes them to simultaneously suppress periodic disturbances of a plurality of frequency components.
[0019]
  (9) The periodic disturbance is a shaft torque detection value of the electric motor, and the disturbance of the shaft torque of the electric motor is suppressed.
[0020]
  (10) The periodic disturbance is a pulsation component of the motor frame, and suppresses the disturbance of the motor frame.
[0021]
  (11) The periodic disturbance is a pulsation component of the rotation speed detection value or rotation position detection value of the motor, and suppresses the disturbance of the speed of the motor or the disturbance of the rotation position.
[0022]
  (12) The periodic disturbance is a pulsation component of the electric current of the electric motor, and suppresses the electric current disturbance of the electric motor.
[0023]
  (13) Torque ripple compensation current i learned in the steady operation state (steady torque command / steady rotation speed) designated when torque ripple suppression control is executed by the controller_qc ^*The amplitude M and phase φ of the torque command T_ref ^*And an amplitude / phase compensation table for generating a two-dimensional amplitude table and a phase table with the rotational speed ω as a variable,
  The torque command T in the operating state of the motor_ref ^*And the rotation speed ω, the amplitude M and the phase φ at that time are read from the amplitude / phase compensation table, and the table compensation current i is obtained using the amplitude M and the phase φ and the rotation phase θ of the motor at that time._qct ^*= Compensation current generator for generating M · sin (nθ + φ),
  The torque ripple compensation current i when torque ripple suppression control is executed by the controller_qc ^*And the table compensation current i_qct ^*And a compensation current synthesizing means for superimposing them on the d and q axis current command values.
[0024]
  (14) Torque ripple compensation current i learned in the steady operation state (steady torque command / steady rotation speed) designated when torque ripple suppression control is executed by the controller_qc ^*The amplitude M and phase φ of the torque command T_ref ^*And an amplitude / phase compensation table for generating a two-dimensional amplitude table and a phase table with the rotational speed ω as a variable,
  The torque command T in the operating state of the motor_ref ^*Then, the amplitude M and phase φ at that time are read from the amplitude / phase compensation table from the rotation speed ω, and the current compensation current amplitude command value M obtained by the amplitude M and phase φ and the controller.^*And compensation current phase command value φ^*Are combined to generate a combined compensation current amplitude value M ′ and a combined compensation current phase value φ ′;
  Using the combined compensation current amplitude value M ′, the combined compensation current phase value φ ′, and the rotational phase θ of the motor at that time, the table compensation current i_qc ^*= M ′ · sin (nθ + φ ′).
[0025]
  (15) Compensation current cosine Fourier coefficient table value A and compensation current sine Fourier coefficient table of torque ripple frequency components learned in a steady operation state (steady torque command / steady rotation speed) designated when torque ripple suppression control is executed by the controller The value B is the torque command T_ref ^*And a Fourier coefficient compensation table for generating a two-dimensional Fourier coefficient compensation table using the rotational speed ω as a variable,
  The torque command T in the operating state of the motor_ref ^*The current Fourier coefficient table values A and B are read from the Fourier coefficient compensation table from the rotation speed ω, and the Fourier coefficient table values A and B and the current compensation in which the controller extracts the torque ripple frequency component by Fourier transform Current cosine Fourier coefficient A^*And compensation current sine Fourier coefficient B^*Are combined to generate a compensation current cosine Fourier coefficient composite value A 'and a compensation current sine Fourier coefficient composite value B';
  Using the Fourier coefficient composite value A ′, the compensation current sine Fourier coefficient composite value B ′, and the rotational phase θ of the motor at that time, the amplitude M = √ (A ′²+ B ’²), Phase φ = tan^-1Table compensation current i of (B '/ A')_qc ^*And a compensation current generator for generating M · sin (nθ + φ).
[0026]
  (16) The compensation table, synthesizing means, and compensation current generating section are provided with means for individually generating an amplitude M and a phase φ or a Fourier coefficient with a plurality of order components and generating a compensation current by synthesizing them according to these orders. It is characterized by that.
[0027]
  (17) In the method in which the controller converts the command value of the motor into a d, q-axis current command value of a rotating coordinate system in vector control, and controls the motor by current control of the inverter according to the current command value.
  The controller uses the frequency component extraction means of Fourier transform to calculate the nth-order Fourier coefficient T from the DC value of the periodic pulsation of the motor._An, T_BnAnd its Fourier coefficient T_An, T_BnIs estimated by a periodic disturbance observer, and a periodic disturbance observer compensator for superimposing a compensation current on the d and q-axis current command values so as to suppress the periodic disturbance. It is characterized by suppressing disturbance.
[0028]
  (18) The frequency characteristic of the control system composed of the inverter and the electric motor is obtained by system identification to obtain a complex vector P_Am, P_BmThe periodic disturbance observer compensator is expressed by a set of the complex vector P corresponding to an arbitrary frequency._Am, P_BmThe inverse system identification model input obtained from_An, T_BnThe periodic disturbance of the nth-order frequency component is estimated as follows.
[0029]
  (19) Amplitude M and phase φ of torque ripple compensation current learned in a steady operation state (steady torque command / steady rotation speed) designated when torque ripple suppression control is executed by the controller, or compensation current cosine Fourier of torque ripple frequency component The coefficient table value A and the compensation current sine Fourier coefficient table value B are set to the torque command T_ref ^*And a two-dimensional compensation table with the rotational speed ω as a variable,
  The torque command T in the operating state of the motor_ref ^*The amplitude M and phase φ or the Fourier coefficient table values A and B at that time are read from the compensation table from the rotation speed ω, and the amplitude M and phase φ or the Fourier coefficient table values A and B and the motor at that time A table compensation current is generated using the rotational phase θ,
  The compensation current and the table compensation current when torque ripple suppression control is executed by the controller are combined and superimposed on the d and q axis current command values.
[Brief description of the drawings]
[0030]
FIG. 1 is a configuration diagram of a disturbance suppression device for an electric motor according to the present invention.
[0031]
FIG. 2 is a basic configuration diagram of disturbance suppression according to the present invention.
[0032]
FIG. 3 is a configuration diagram of a torque pulsation compensation device using a system identification device.
[0033]
FIG. 4 is a configuration diagram of a disturbance suppression control system.
[0034]
FIG. 5 is an explanatory diagram of the effect of disturbance suppression.
[0035]
FIG. 6 is a configuration diagram of a disturbance suppression control system according to a second embodiment.
[0036]
7 is a configuration diagram of a disturbance suppression control system of Embodiment 3. FIG.
[0037]
FIG. 8 is a configuration diagram of a disturbance suppression control system according to a fourth embodiment.
[0038]
FIG. 9 is a configuration diagram of a disturbance suppression control system according to a fifth embodiment.
[0039]
FIG. 10 is a configuration diagram of a disturbance suppression control system according to a seventh embodiment.
[0040]
FIG. 11 is a configuration diagram of a disturbance suppression device according to an eighth embodiment.
[0041]
FIG. 12 is a configuration diagram of a disturbance suppression device according to a ninth embodiment.
[0042]
FIG. 13 is a configuration diagram of a disturbance suppression device according to a tenth embodiment.
[0043]
FIG. 14 is a configuration diagram of a disturbance suppression device according to an eleventh embodiment.
[0044]
FIG. 15 is a configuration diagram of a disturbance suppression device according to a twelfth embodiment.
[0045]
FIG. 16 is a configuration diagram of a disturbance suppression device according to a thirteenth embodiment.
[0046]
FIG. 17 is a configuration diagram of a disturbance suppression device according to a fourteenth embodiment.
BEST MODE FOR CARRYING OUT THE INVENTION
[0047]
  (Basic configuration)
  Before describing the embodiment of the present invention, the basic configuration of a disturbance suppression device according to the present invention will be described.
  FIG. 1 shows the configuration of a disturbance suppression device for an electric motor according to the present invention. An electric motor 1 that is a generation source of torque pulsation and some load device 2 are coupled by a shaft 3, and the shaft torque is measured by a torque meter 4 and input to a controller 5. Moreover, the rotor position information of the electric motor is input using a rotational position sensor 6 such as a rotary encoder. The controller 5 is equipped with torque pulsation suppression means, and gives the inverter 7 a command value obtained by adding a torque pulsation compensation current to the current command value generated based on the torque command value (or speed command value). In the example of FIG. 1, in consideration of the current vector control by the inverter 7, the d-axis and q-axis current command values id on the rotation coordinates (orthogonal dq axes) synchronized with the rotation of the motor.^*, Iq^*Is given.
[0048]
  The controller 5 detects torque pulsation from the torque detection value by the shaft torque meter 4, but this form is only an example, and vibration detection by an acceleration sensor installed in the frame, rotation speed fluctuation detection by an encoder, etc., or current Instead of detecting current pulsation by a sensor, it is possible to suppress disturbance of the motor shaft, disturbance of the frame of the motor, suppression of disturbance of the speed of the motor or disturbance of the rotational position, and suppression of disturbance of the current of the motor.
[0049]
  It is known that torque pulsation periodically occurs according to the rotor position due to the structure of the electric motor. The torque pulsation of the three-phase motor is mainly a frequency 6 × n times the electrical rotation fundamental frequency (n is a positive integer: hereinafter, the 6-fold component is expressed as 6f, the 12-fold component is expressed as 12f, etc.) It is also known that the component becomes large. In addition, 1f and 2f torque pulsations may appear due to incompleteness of the inverter power supply, current sensor offset, and the like. Further, in a system in which axial torsional resonance can occur as shown in FIG. 1, a pulsation component close to the mechanical resonance point is amplified and appears in the detected axial torque value.
[0050]
  In the present invention, the torque pulsation in which these various frequency components are mixed is extracted based on Fourier transform. That is, the controller 5 in FIG._detIs subjected to Fourier transform for each arbitrary order using information on the motor rotor phase θ≡. Here, the Fourier series is defined by Equation 1 and Equation 2 below. ω is electrical angular frequency, T_rMeans one cycle of an arbitrarily defined pulsating component. Note that the integration of the Fourier transform can be simply changed to a low-frequency pass filter (low-pass filter) having an arbitrary time constant. That is, any means for extracting a high frequency component (torque pulsation) as a direct current value may be used.
[Expression 1]

[Expression 2]

[0051]
  Fourier coefficient T expressed by Equation 2_An, T_BnFocuses on outputting a DC value if the motor rotation speed and the pulsating component, which is a periodic disturbance, are constant in an arbitrary period. If some control is given and both of these coefficients are zero and steady, it means that the torque pulsation of the frequency component has been suppressed.
[0052]
  Therefore, in the present invention, the Fourier transform is performed for each arbitrary pulsation frequency component, the periodic disturbance observer compensator is configured so that the two Fourier coefficients are 0, and the compensation current is superimposed on the current command value of the vector control inverter. To do. Hereinafter, a basic configuration of disturbance suppression according to the present invention will be described with reference to FIG.
[0053]
  FIG. 2 develops control blocks based on the system configuration of FIG. The command value conversion unit 11 is a torque command value T_refTo the d-axis and q-axis current command values I of the rotation dq coordinate system in vector control._do, I_qo(For example, maximum torque control) and torque pulsation compensation current is superimposed on the current command value to suppress torque pulsation. In the example of FIG. 2, the compensation current i is added to the q-axis current command value._qcAre superimposed, but may be applied to the d-axis current or both the d-axis and the q-axis. Alternatively, in a system where interference of dq axis current does not become a problem, a torque pulsation compensation signal may be directly superimposed on the torque command value. The inverter 12 is a general electric motor drive device that realizes current vector control in the d-axis and q-axis converted from the three-phase rotational coordinates, and drives the electric motor load 13.
[0054]
  The sine / cosine wave generator 14 sets the rotor phase angle θ of the motor load 13 and the order n of the pulsating component to be suppressed, and generates a sine / cosine wave having a reference frequency. In the Fourier transform unit 15, the sine / cosine wave and an arbitrary Fourier transform period T_rTo set the shaft torque detection value T_detIs Fourier-transformed based on Equation 2, and the nth-order Fourier coefficient T_An, T_BnIs calculated. Here, it is also possible to replace the integration process of the Fourier transform of Formula 2 with a low frequency band pass filter (low pass filter) having an appropriate time constant.
[0055]
  Next, the Fourier coefficient T of the pulsation component_An, T_BnThe periodic disturbance observer compensator 16 is configured so that becomes 0 (that is, pulsation is suppressed). Details of this portion will be described in an embodiment described later. Output I of periodic disturbance observer compensator 16_An, I_BnIs the Fourier coefficient of the compensation current signal, and the multipliers 17A and 17B multiply the nth-order sine and cosine waves, respectively, to perform inverse transformation. That is, it is restored as a compensation current signal having a time waveform. Restored pulsation compensation current iqc^*Is added to the q-axis current command value iq0 of the vector control inverter 7 by an adder.^*Superimpose on.
[0056]
  As described above, instead of directly detecting the shaft torque pulsation, torque estimated by an observer or the like from the inverter current or speed detection value may be used, or the motor housing frame vibration or the like is detected by an acceleration sensor, It is also conceivable to perform vibration suppression.
[0057]
  In the present invention, in order to simplify the description of the core control method, an embodiment will be described below by taking as an example a case where torque is directly detected by an axial torque meter or the like.
[0058]
  (Embodiment 1)
  In the present embodiment, the process starts by grasping in advance the frequency characteristics of the motor drive system. There are various methods for grasping frequency characteristics and system identification, but these are known general techniques, and the present invention is not limited to specific methods. For example, as shown in FIG. 3, the system identification device 18 inputs the white noise signal as a torque pulsation compensation current to the actual system and superimposes it on the current command value in any steady operation state (FIG. 3 shows the q-axis current). Although they are superimposed, they may be d-axis or both). System input / output data is obtained using the detected shaft torque value as a system output signal. It is possible to obtain a frequency transfer function from the pulsation compensation current command value to the shaft torque detection value by spectrum analysis of the frequency response from the input / output time series data. Although it is possible to formulate based on the system identification theory or to obtain parameters based on a physical model (for example, a two-inertia system model), in this embodiment, the frequency transfer function is complex as shown in Equation 3. Expressed as a set of vectors. The elements of the set correspond to complex vectors indicating gain / phase characteristics in each frequency component.
[Equation 3]

  Where Psys ^: identification system, m: frequency component division element number, P_Am: M-th element identification system real part, P_Bm: Mth element identification system imaginary part
[0059]
  Here, the division element number m will be described. For example, if the frequency component necessary for identification is DC to 5 kHz and the resolution is 1 Hz, the number of elements is 5001. Therefore, as m = {0, 1, 2, 3,..., 4999, 5000}, a spectrum analysis result or a system identification result is applied to each element (frequency component). Since the gain / phase characteristic of the system for each frequency component can be expressed by a complex vector on the complex plane, it can be expressed as in Equation 3.
[0060]
  When Fourier transform is used, torque pulsation of an arbitrary frequency component can be extracted with a Fourier coefficient. As shown in Equation 2, since the two Fourier coefficients have orthogonality, if one element of the complex vector of Equation 3 above is extracted focusing on only the system state of any frequency component, its real part and imaginary part Can be compared to two Fourier coefficients. That is, here, the real part is adapted to the cosine Fourier coefficient and the imaginary part is adapted to the sine Fourier coefficient (for example, the counterclockwise direction is defined as the delayed phase, and P_BmInvert the polarity to match.)
[0061]
  From the above, if attention is paid only to the arbitrary frequency component after Fourier transform, the periodic disturbance (torque pulsation) of the frequency component and the pulsation for suppressing it using the complex vector of Equation 3 that means system characteristics The relationship between the Fourier coefficient of the compensation current signal and the detected torque pulsation value can be grasped. In addition, since these relationships are all expressed by a DC component by Fourier transform, the periodic disturbance also becomes a DC value at that frequency.
[0062]
  Here, as shown in FIG. 4, a disturbance suppression control system considering only one arbitrary frequency component is considered, and a periodic disturbance observer compensator for estimating and compensating for the periodic disturbance is configured. That is, an error from the compensation current command value is obtained from the detected axial torque pulsation value via the inverse system of Equation 4 (reciprocal of the complex vector), and the error is regarded as a periodic disturbance current corresponding to the periodic disturbance. Then, the error compensation amount is superimposed as a compensation current command value so as to cancel the disturbance.
[Expression 4]

[0063]
  FIG. 4 will be described. Characteristics P of real system 19_sysAs in Equation 4, (n-order component) is considered to be represented by a one-dimensional complex vector for a certain frequency component. The input has a compensation current i_qcnAnd the periodic disturbance torque T_rplnPulsation compensation torque T to cancel_cnIs generated. Since the torque pulsation is extracted by the Fourier transform, the response transfer function G of the Fourier transform unit 20_FTFourier coefficient T of torque pulsation detection value via_An, T_BnGet. These are complex vectors T_An+ T_BnReplace with i.
[0064]
  Next, the nth-order disturbance observer 21 obtains current input information including the disturbance current using the reciprocal of the frequency transfer function identified in Formula 4 (not including the disturbance), and subtracts the compensation current command value therefrom. The periodic disturbance current dI_An, DI_BnIs estimated. G_OBSIs used to stabilize the pulsation compensation by inserting an arbitrary filter (for example, a low-pass filter) to suppress the influence of residual pulsation and disturbance estimation error during Fourier transform extraction.
[0065]
  As described above, the periodic disturbance is estimated, and the current dI corresponding to the disturbance is calculated from the target value (usually 0 when the periodic disturbance is suppressed)._An, DI_BnSubtracting the compensation current i_qcnIs generated.
[0066]
  FIG. 5 shows the disturbance suppression effect when the present embodiment is applied. From the top, the waveforms are the detected shaft torque value [Nm], the torque pulsation Fourier coefficient [Nm], the compensation current Fourier coefficient [A], and the torque pulsation amplitude evaluation value [Nm]. As an example, only the 12th pulsation component is shown.
[0067]
  From the shaft torque waveform, it can be seen that the torque pulsation appears larger than the steady torque before the suppression starts, but the pulsation is greatly reduced after the suppression. It can be seen that the sine / cosine Fourier coefficient of the torque pulsation is 0 after suppression.
[0068]
  (Embodiment 2)
  In the present embodiment, the filter of the nth-order disturbance observer 21 in FIG. 4 is separated on the command value side and the detection value side. A configuration example of this embodiment is shown in FIG.
[0069]
  For example, considering pulsation extraction by Fourier transform, communication / calculation delay time, etc._OBS, G_LPFIt is also possible to set the filter characteristics separately.
[0070]
  According to the present embodiment, the disturbance suppression characteristics can be obtained in which the filter characteristics on the command value side and the detection value side of the periodic disturbance observer are set separately, and the delay of the detection system is taken into account.
[0071]
  (Embodiment 3)
  In the present embodiment, in consideration of the case where the rotation speed of the motor changes, both the Fourier transform cycle and the cutoff frequency of the disturbance observer filter are made variable using the rotation speed detection value (or estimated value) of the motor. FIG. 7 is a configuration example of this embodiment.
[0072]
  When the rotational speed changes, one element (one-dimensional complex vector) to be extracted and applied from the complex vector set of Equation 3 also changes, so that it adapts to the speed (P_sys)^-1Is also variable. In addition, the observer filter G according to the rotation speed_OBSCut-off frequency and Fourier transform response G_FTAlso, it is adapted so that a stable pulsation suppressing effect can be always obtained.
[0073]
  According to this embodiment, it is possible to suppress periodic disturbance by sequentially adapting to fluctuations in the rotational speed.
[0074]
  (Embodiment 4)
  When a frequency component is extracted using Fourier transform or the like, the extraction time is required for a certain period, and a sufficient disturbance suppression response speed may not be obtained. For example, when trying to cope with variable speed operation and quasi-steady torque fluctuation exceeding the response, the suppression effect may be insufficient.
[0075]
  Therefore, in the present embodiment, after suppressing the torque pulsation using the periodic disturbance suppressing means described above, two Fourier coefficients of the pulsation compensation current are recorded in the memory in a steady state at the arbitrary operating point. Such a memory recording process is performed in advance in the same manner at each operating point, and a compensation current Fourier coefficient table having the rotational speed and the torque command value as inputs is created. Instead of the table, an approximate function using the rotation speed and the torque command value as parameters may be used. After generating the compensation table, two compensation current Fourier coefficients are read from the table according to the operating point, and a pulsation compensation current is generated and applied by feedforward.
[0076]
  FIG. 8 is a configuration example of this embodiment. The difference from FIG. 2 is that the rotational speed W is calculated by the rotational speed calculator 22 from the rotor phase angle θ._mAnd the torque command value T_refFrom the compensation table 23 (or compensation approximation function), the compensation current Fourier coefficient I_An, I_BnIs read.
[0077]
  According to this embodiment, since the Fourier coefficient of the pulsation compensation current is learned in advance and can be suppressed only by reading the coefficient, it is possible to instantly cope with a sudden change in the operating point such as the rotational speed and torque. Is possible.
[0078]
  (Embodiment 5)
  In this embodiment, in addition to the fourth embodiment, the temperature of the electric motor is detected, a change in system characteristics due to a temperature change is detected, and a table or an approximate function is formed at each operating point as in the fourth embodiment. .
[0079]
  FIG. 9 is a configuration example of this embodiment. The part different from FIG. 8 is to measure the temperature t of the motor load 13 and incorporate this temperature t as a compensation parameter of the compensation table 23.
[0080]
  According to this embodiment, it is possible to cope with a system having a strong temperature dependency.
[0081]
  (Embodiment 6)
  In the present embodiment, the periodic disturbance suppression control in which shaft torque detection is fed back and the feedforward compensation method based on the learned compensation table (or approximate expression) are switched and used. A rotation speed or a torque command value is used as a reference for switching control.
[0082]
  For example, when looking at the change rate of the rotational speed or the torque command value and inputting a command value change rate equal to or higher than the Fourier transform response, the method is switched to the method using the compensation table. In quasi-steady operation with a small change rate, periodic disturbance suppression means by constant feedback is used.
[0083]
  Since the compensation means by feedforward may not be able to sufficiently cope with perturbation changes of system characteristics depending on the system to be applied, the feedforward operation can be minimized by using the means for switching the operation state as described above. Can be.
[0084]
  (Embodiment 7)
  The above embodiments have been periodic disturbance suppression control means for any one pulsation frequency component, but if the configurations in each embodiment are parallelized, frequency components of a plurality of periodic disturbances can be suppressed. Is possible.
[0085]
  A block diagram of this embodiment is shown in FIG.₁~ 24_nIs a control element that suppresses the pulsation component according to the first to nth orders of the Fourier series._qc1~ I_qcnAre superimposed on each other by the adder 25, and the torque pulsation compensation signal i_qcAnd
  According to this embodiment, a plurality of torque pulsations can be suppressed simultaneously. Further, since these can be simultaneously suppressed in parallel, it is an effective means even when disturbance suppression of one frequency component adversely affects periodic disturbance of another frequency component.
[0086]
  (Embodiment 8)
  In the embodiments described above, the torque pulsation compensation method or method has been proposed based on the configuration that feeds back the shaft torque, but the object to be fed back can be changed.
[0087]
  In the present embodiment, as shown in FIG. 11, the acceleration sensor 8 detects the vibration of the frame / housing of the motor and feeds it back. The disturbance suppression control method is the same as in the above embodiments.
[0088]
  According to the present embodiment, it is possible to suppress the disturbance of the casing of the electric motor.
[0089]
  (Embodiment 9)
  In the present embodiment, as shown in FIG. 12, the fluctuation of the phase / speed information provided from the rotational position sensor 6 is detected, and control is performed so as to suppress the fluctuation. The control contents are basically the same as those in the above-described embodiments.
[0090]
  According to the present embodiment, periodic speed fluctuations and phase fluctuations can be suppressed.
[0091]
  (Embodiment 10)
  In the present embodiment, as shown in FIG. 13, the current sensor 9 detects the current of the three-phase line that supplies power from the inverter 7 to the pulsation compensation target electric motor 1, and suppresses the current disturbance.
  According to the present embodiment, the estimated disturbance torque pulsation can be suppressed by suppressing the inverter current disturbance using the detected inverter current value or by using the estimated torque value converted from the inverter current.
[0092]
  (Embodiment 11)
  In the torque ripple suppression control according to the above-described embodiments, the Fourier transform is performed for each arbitrary pulsation frequency component, and the periodic disturbance observer is configured so that the two Fourier coefficients are 0, thereby performing stable control in the entire frequency band. The “on-line compensation method” is obtained. According to this online compensation method, torque ripple can be suppressed by always online feedback even for a system having variable speed and load fluctuation. In addition, since it has a function of automatically adjusting the periodic disturbance observer model using the system identification result expressed by a one-dimensional complex vector, it can be implemented in a multi-inertia resonance system.
[0093]
  In addition, since the “online compensation method” is constantly learning, it is possible to cope with changes over time in the electric motor and inverter characteristics. However, since the learning algorithm always needs to be operated, the computation load is relatively high. Even when the load device of the motor is changed, the system needs to be re-identified, and learning time is required, so it can respond quickly to variable speed operation and torque changes. There is a problem with inferiority.
[0094]
  The eleventh embodiment and the following twelfth to fourteenth embodiments can suppress torque ripple by on-line compensation that can cope with changes in electric motors and inverters over time, and reduce computation load, eliminate the need for re-identification of the system, and have responsiveness. The present invention proposes a control device and method capable of suppressing torque ripple.
[0095]
  FIG. 14 shows a block configuration of the torque control apparatus for an electric motor according to this embodiment, and shows a case where torque ripple suppression is performed by an on-line compensation method for controlling an inverter of a current vector control method.
[0096]
  In FIG. 14, the current vector control unit 31 of the inverter 7 includes a motor drive current i detected by the current sensor 32._u, I_v, I_wThe motor current is controlled by comparing the rotor rotation angle θ of the motor 1 with the d and q axis current detection values converted into the current of the dq axis orthogonal rotation coordinate system synchronized with the motor rotation coordinates by the coordinate conversion unit 33. The rotor rotation angle θ is obtained from the encoder waveform abz by the rotational position sensor 6 together with the speed ω by the speed / phase detector 34.
[0097]
  The torque / id, iq conversion unit 35 (command value conversion unit 11) is a torque command value T from the controller 5._refAnd the motor rotation speed ω, the d-axis and q-axis current command values i of the rotation dq coordinate system in vector control_d ^*(I_do), I_q0 ^*(I_qo) And q-axis current command value i out of these current command values_q0 ^*Torque pulsation compensation current i_qcmIs used as a current vector control command value.
[0098]
  As in FIG. 1, the controller 5 is equipped with torque ripple suppression control means. Examples of the torque ripple suppression control means include a sine / cosine wave generator 14, a Fourier transform unit 15, and a periodic disturbance observer compensator 16 shown in FIG. 2. And the Fourier coefficient T of the pulsating component by the multipliers 17A and 17B._An, T_BnTorque ripple compensation current such that becomes zero, and this torque ripple compensation current i_qc ^*Is the q-axis current command value i of the vector control inverter 7_q0 ^*To make a compensation signal.
[0099]
  Here, in the present embodiment, on the basis of the “online compensation method”, a compensation current generation unit that suppresses in a feedforward manner is added using a compensation table learned in advance. As this compensation current generation means, an amplitude / phase compensation table 36 and a compensation current generator 37 are provided.
[0100]
  The amplitude / phase compensation table 36 stores the torque ripple compensation current i learned in the steady operation state (steady torque command / steady rotation speed) designated when the torque ripple suppression control is executed by the controller 5._qc ^*Record the amplitude M and the phase φ. This operation is similarly recorded at a plurality of steady operation points, and the torque command T_ref ^*And a two-dimensional amplitude table and phase table using the rotational speed ω as variables. Information between data is interpolated by linear interpolation or the like.
[0101]
  The compensation current generation unit 37 reads the current amplitude M and phase φ from the operating state (torque command / rotation speed) from the amplitude / phase compensation table 36, and the read amplitude M and phase φ are the rotational phase at that time. Table compensation current i using θ_qct ^*= M · sin (nθ + φ) is generated (n is the compensation order). This generated table compensation current i_qct ^*Is the online compensation current i_q0 ^*And q-axis current command value i_qcm ^*And
  Therefore, the table compensation current i_qct ^*Since the compensation current is generated by instantaneously obtaining the amplitude and phase from the learned compensation current table, a suitable compensation current can be quickly output even when a speed change or a torque change occurs. In addition, even if the torque ripple deviates from the characteristics at the time of learning due to changes in ambient temperature or changes in physical properties over time, the online compensation feedback loop works, so the error in the table compensation current can be corrected. .
[0102]
  Embodiment 12
  FIG. 15 shows a block configuration of the torque control apparatus for an electric motor according to the present embodiment, and the basic configuration and operation are the same as those in FIG. 14, but errors in the amplitude M and phase φ of the compensation current generated in the compensation table 36 are shown. An online compensation feedback loop is constructed from the controller 5 to correct.
[0103]
  In FIG. 15, M^*Is the compensation current amplitude command value (online compensation), φ^*Is a compensation current phase command value (on-line compensation), and the synthesizers 38 and 39 synthesize these with the compensation current amplitude M and phase φ, respectively, and the compensation current amplitude value (synthesis value) to the compensation current generator 37 Let M ′ be the compensation current phase value (composite value) φ ′.
[0104]
  In the eleventh embodiment, the table compensation current i is generated after the compensation current is generated._qct ^*And online compensation current i_qc ^*However, in this embodiment, they are synthesized in the state of amplitude and phase. That is, the compensation table amplitude value M and the compensation table phase value φ are respectively set to the online compensation amplitude value M.^*And online compensation phase value φ^*To generate a combined compensation current amplitude value M ′ and a combined compensation current phase value φ ′. In the compensation current generator 37, i_qc ^*= M ′ · sin (nθ + φ ′), the final compensation current i_qc ^*Is generated. (N is the compensation order)
[0105]
  According to the present embodiment, the table error can be grasped and corrected with an intuitively easy-to-understand state quantity such as amplitude and phase, and the compensation current generator 37 can be gathered in one place.
[0106]
  (Embodiment 13)
  FIG. 16 shows a block configuration of the torque control apparatus for an electric motor according to the present embodiment, which is replaced with a cosine Fourier coefficient and a sine Fourier coefficient instead of the compensation table amplitude M and phase φ in the twelfth embodiment (FIG. 15). .
[0107]
  The compensation table 40 has a torque command T_ref ^*The compensation current cosine Fourier coefficient table value A and the compensation current sine Fourier coefficient table value B are generated according to the rotation speed ω, and the controller 5 generates the online compensation current cosine Fourier coefficient A.^*And online compensation current sine Fourier coefficient B^*The combiners 38 and 39 combine these to obtain a compensation current cosine Fourier coefficient composite value A 'and a compensation current sine Fourier coefficient composite value B'.
[0108]
  The controller 5 equipped with the torque ripple suppression control function basically uses a technique for extracting and suppressing the torque ripple frequency component by Fourier transform (or a similar technique). In FIG. 2, there are real and imaginary components of a complex vector corresponding to two Fourier coefficients, and the amplitude value and phase value of the compensation current are calculated using these components.
[0109]
  In the configuration of FIG. 2, the real part component of the compensation current generated by the periodic disturbance observer compensator 16 is represented by B (I_Bn), The imaginary part component is A (I_An). From these, the amplitude M and the phase φ are obtained as follows.
[0110]
    M = √ (A²+ B²), Φ = tan^-1(B / A)
[0111]
  In the eleventh and twelfth embodiments, the compensation table is generated or the online compensation is performed after obtaining the amplitude M and the phase φ. While the compensation current characteristic is easy to understand intuitively, the above-described arithmetic conversion is required. It was.
[0112]
  Therefore, in the present embodiment, as shown in FIG. 16, a compensation table is generated in the state of two Fourier coefficients A and B before being converted into amplitude and phase, and online compensation is also synthesized in the state of the Fourier coefficient. , Compensation current i in the last stage_qc ^*Is generated. As a result, it is possible to save the labor of the above-described calculation for converting into amplitude / phase and simplify the compensation process.
[0113]
  (Embodiment 14)
  In the present embodiment, there is provided a method of parallelizing the configurations of any of the embodiments 11 to 13 and simultaneously suppressing the torque ripple of the multi-order component.
[0114]
  For example, FIG. 17 shows a case where the configuration of the eleventh embodiment is parallelized. (This is the same for the other embodiments, so the explanation is omitted in the drawing.) FIG. 17 shows that the two compensation components 36A and 36B individually generate the amplitude M and the phase φ with the two order components. The two compensation current generators 37A and 37B generate compensation currents for two orders, and simultaneously suppress torque ripple for these two orders. Of course, it is possible to extend the case where three or more orders are simultaneously suppressed.
[0115]
  As described above, according to the present invention, the Fourier transform is performed for each arbitrary pulsation frequency component, the periodic disturbance observer compensator is configured so that the two Fourier coefficients are 0, and the compensation current is set to the current of the vector control inverter. Since it is superposed on the command value, it is possible to suppress disturbances in a complicated electric motor system and to perform stable control in which periodic torque pulsation is suppressed.
[0116]
  Furthermore, based on the “online compensation method”, a compensation current that has been learned in advance is used in combination to generate a compensation current that is suppressed in a feed-forward manner. Torque ripple suppression can be suppressed.

Claims (19)

The controller converts the command value of the motor into d and q-axis current command values of the rotating coordinate system in vector control, and controls the motor by current control of the inverter according to the current command values.
The controller detects n-order Fourier coefficients T _An and T _Bn from the DC value of the periodic pulsation of the motor by means of frequency component extraction means of Fourier transform, and n-order frequency components having the Fourier coefficients T _An and T _Bn. Means for suppressing the disturbance by the periodic disturbance observer compensator for estimating the upper periodic disturbance by the periodic disturbance observer and superimposing the compensation current on the d and q axis current command values so as to suppress the periodic disturbance. A disturbance suppressing device for an electric motor, comprising: The frequency characteristic of the control system composed of the inverter and the motor is expressed as a set of complex vectors P _Am and P _Bm by system identification, and the periodic disturbance observer compensator is obtained from the complex vectors P _Am and P _Bm corresponding to an arbitrary frequency. 2. The disturbance suppression device for an electric motor according to claim 1, further comprising means for estimating periodic disturbance of an nth-order frequency component using the input of the obtained inverse system identification model as the Fourier coefficients T _An and T _Bn . The periodic disturbance observer compensator, the estimated periodic disturbance from the compensation current command value periodic disturbance current dI An by _subtracting, dI _Bn look, the periodic disturbance current dI from the current command value _An, dI _Bn The disturbance observer filter that subtracts periodic disturbance from the compensation current command value and the disturbance observer filter that extracts the estimated periodic disturbance have different characteristics. Item 3. A disturbance suppression device for an electric motor according to Item 1 or 2. 4. The disturbance suppression of the electric motor according to claim 1, further comprising means for variably setting the characteristics of the periodic disturbance observer compensator and the Fourier transform unit in accordance with a rotation speed. 5. apparatus. In a steady operation state of an arbitrary frequency, the periodic disturbance observer compensator previously learns and records the Fourier coefficient of the pulsation compensation current at a plurality of operating points, and a compensation current Fourier coefficient table using the rotation speed and torque as input parameters, or The disturbance suppression device for an electric motor according to any one of claims 1 to 4, further comprising means for generating an approximate function and providing a pulsation compensation current by feedforward control. 6. The disturbance suppression device for an electric motor according to claim 5, wherein the compensation current Fourier coefficient table or the approximate function includes a detected temperature value of the electric motor as a parameter. The periodic disturbance suppression by the feedforward control is performed only when the rotation speed or the torque command value exceeds a certain rate of change, and switching to the periodic disturbance suppression by feedback is performed during other steady or quasi-steady operation. The disturbance suppression device for an electric motor according to claim 5 or 6. 8. The periodic disturbance observer compensator is applied to different frequency components, and parallelized to suppress periodic disturbances of a plurality of frequency components at the same time. A disturbance suppression device for an electric motor according to claim 1. The disturbance disturbance device for an electric motor according to claim 1, wherein the periodic disturbance is a detected value of an axial torque of the electric motor, and the disturbance of the axial torque of the electric motor is suppressed. The disturbance disturbance device for an electric motor according to claim 9, wherein the periodic disturbance is a pulsation component of the frame of the electric motor and suppresses the disturbance of the electric motor frame. 10. The electric motor disturbance according to claim 9, wherein the periodic disturbance is a pulsation component of a rotation speed detection value or a rotation position detection value of the motor, and suppresses the disturbance of the motor speed or the rotation position. Suppressor. The disturbance disturbance device for an electric motor according to claim 9, wherein the periodic disturbance is a pulsation component of the electric current of the electric motor, and suppresses the electric current disturbance of the electric motor. The amplitude M and the phase φ of the torque ripple compensation current i _qc ^* learned in the steady operation state (steady torque command / steady rotation speed) designated when the torque ripple suppression control is executed by the controller, the torque command T _ref ^* and the rotation speed. An amplitude / phase compensation table for generating a two-dimensional amplitude table and a phase table with ω as a variable;
The amplitude M and phase φ at that time are read from the torque command T _ref ^* and the rotational speed ω in the operating state of the motor from the amplitude / phase compensation table, and the amplitude M and phase φ and the rotational phase θ of the motor at that time are read out. A compensation current generation unit that generates a table compensation current i _qct ^* = M · sin (nθ + φ) using
Compensation current synthesis means for synthesizing the torque ripple compensation current i _qc ^* and the table compensation current i _qct ^* when torque ripple suppression control is executed by the controller and superimposing them on the d and q axis current command values is provided. The disturbance suppression device for an electric motor according to any one of claims 1 to 12. The amplitude M and the phase φ of the torque ripple compensation current i _qc ^* learned in the steady operation state (steady torque command / steady rotation speed) designated when the torque ripple suppression control is executed by the controller, the torque command T _ref ^* and the rotation speed. An amplitude / phase compensation table for generating a two-dimensional amplitude table and a phase table with ω as a variable;
The amplitude M and phase φ at that time are read out from the amplitude / phase compensation table from the torque command T _ref ^* and the rotational speed ω in the operating state of the motor, and the amplitude M and phase φ and the current obtained by the controller Combining means for combining the compensation current amplitude command value M ^* and the compensation current phase command value φ ^* to generate a combined compensation current amplitude value M ′ and a combined compensation current phase value φ ′;
Compensation current generation for generating a table compensation current i _qc ^* = M ′ · sin (nθ + φ ′) using the combined compensation current amplitude value M ′, the combined compensation current phase value φ ′, and the rotational phase θ of the motor at that time The disturbance suppression device for an electric motor according to any one of claims 1 to 12, further comprising: The compensation current cosine Fourier coefficient table value A and the compensation current sine Fourier coefficient table value B of the torque ripple frequency component learned in the steady operation state (steady torque command / steady rotation speed) designated when the torque ripple suppression control is executed by the controller. A Fourier coefficient compensation table for generating a two-dimensional Fourier coefficient compensation table using the torque command T _ref ^* and the rotational speed ω as variables;
The Fourier coefficient table values A and B at that time are read from the Fourier coefficient compensation table from the torque command T _ref ^* and the rotational speed ω in the operating state of the electric motor, and the Fourier coefficient table values A and B and the controller The current compensation current cosine Fourier coefficient A ^* and the compensation current sine Fourier coefficient B ^* , which extract the torque ripple frequency component by Fourier transform, are respectively synthesized to form the compensation current cosine Fourier coefficient composite value A ′ and the compensation current sine Fourier coefficient composite value B ′. A synthesis means for generating
The Fourier coefficients composite values using the rotational phase θ of the motor A 'and the compensation current sine Fourier coefficient synthesis value B' and at that time, the amplitude ^{M = √ (A '2 +} B' 2), the phase φ = tan ^-1 ( The electric motor according to claim 1, further comprising: a compensation current generation unit that generates a table compensation current i _qc ^* = M · sin (nθ + φ) of B ′ / A ′). Disturbance suppression device. The compensation table, the synthesizing means, and the compensation current generating unit are provided with means for individually generating an amplitude M and a phase φ or a Fourier coefficient with a plurality of order components, and generating a compensation current by synthesizing by each order. The disturbance suppression device for an electric motor according to any one of claims 13 to 15. The controller converts the command value of the motor into a d, q-axis current command value of a rotating coordinate system in vector control, and controls the motor by current control of the inverter according to the current command value.
The controller detects n-order Fourier coefficients T _An and T _Bn from a DC value of periodic pulsation of the motor by means of frequency component extraction means of Fourier transform, and n-order frequency components having the Fourier coefficients T _An and T _Bn. The above periodic disturbance is estimated by a periodic disturbance observer, and the disturbance is suppressed by a periodic disturbance observer compensator that superimposes a compensation current on the d and q axis current command values so as to suppress this periodic disturbance. An electric motor disturbance suppression method characterized by the above. The inverter and comprising an electric motor control system complex vector P _Am by a system identification frequency characteristics _of, and represented by a set of P _Bm, the periodic disturbance observer compensator the complex vector P _Am corresponding to an arbitrary frequency _from P _Bm 18. The disturbance disturbance suppression method for an electric motor according to claim 17, wherein a periodic disturbance of an nth-order frequency component is estimated with the input of the obtained inverse system identification model as the Fourier coefficients T _An and T _Bn . Amplitude M and phase φ of torque ripple compensation current learned in steady operation state (steady torque command / steady rotation speed) designated when torque ripple suppression control is executed by the controller, or compensation current cosine Fourier coefficient table value of torque ripple frequency component A two-dimensional compensation table with the torque command T _ref ^* and the rotational speed ω as variables is generated for A and the compensation current sine Fourier coefficient table value B,
The amplitude M and phase φ or the Fourier coefficient table values A and B at that time are read from the torque table T _ref ^* and the rotational speed ω in the operating state of the motor from the compensation table, and the amplitude M and phase φ or the Fourier Using the coefficient table values A and B and the rotational phase θ of the motor at that time, a table compensation current is generated,
The motor disturbance according to claim 17 or 18, wherein the compensation current and the table compensation current when torque ripple suppression control is executed by the controller are combined and superimposed on the d and q-axis current command values. Repression method.

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