JP3757552B2 - Brushless DC motor drive control method and apparatus - Google Patents

Description

このことを考慮すると、図１２（Ｂ）のように、ｎ回目のパルス（図１２（Ｂ）ではロー状態）においては、パルス幅Ｔの値Ｔ_nが現時点で不明であっても、前回値Ｔ_n-1が現時点で判っているため、位置信号Ｓｉｎｔの遷移（この場合はトレイリングエッジ）を原点「０」として、末尾エッジの認識は「（３／４）×Ｔ_n-1」の時点Ｔｍ３以降に行えば足りることになる。したがって、ｎ回目のパルス（この場合のパルス幅Ｔの値Ｔ_nは現時点で不明である）においては、遷移の時点「０」を経過した後「（３／４）×Ｔ_n-1」の時点Ｔｍ３までの間は、一切の信号変化を無視しても差支えなく、この部分のノイズをキャンセルすることが可能である。なお、図１２（Ｂ）では、「（１／２）×Ｔ_n-1」の時点から「（３／４）×Ｔ_n-1」の時点Ｔｍ３までをキャンセルする例を図示している。
【００１６】
しかしながら、かかる提案例であっても、「（３／４）×Ｔ_n-1」の時点Ｔｍ３以降にノイズが入った場合にはこのノイズをキャンセルすることは不可能である。そして、この「（３／４）×Ｔ_n-1」の時点Ｔｍ３以降のノイズにより誤ったＴ_nを検出すると誤動作を来す可能性が高く、ひいてはインバータ停止をもたらす恐れがある。
【００１７】
そこで、この発明の課題は、マイコンに与えられる位置信号のノイズの影響を解消し得るブラシレスＤＣモータ駆動制御方法及びその装置を提供することにある。
【００１８】
【課題を解決するための手段】
上記課題を解決すべく、請求項１に記載の発明は、ブラシレスＤＣモータの回転子と固定子との相対的な回転位置に応じてレベルが切り換わる位置信号に基づいた電圧パターンを与えるブラシレスＤＣモータ駆動制御方法であって、前記位置信号に現れる遷移を検知した第１の時点から所定の遅延時間が経過した第２の時点において前記レベルを検出する工程を前記第１の時点を更新しつつ繰返し、前記第１の時点の更新の度に、その前後で前記レベルが同一であれば、最新に検知された遷移をリーディングエッジとするパルスを無視する一方、異なれば、最新に検知された遷移をリーディングエッジとするパルスのパルス幅に基づいて、前記電圧パターンを制御するものである。
【００１９】
そして当該ブラシレスＤＣモータ駆動制御方法が、前記ブラシレスＤＣモータ駆動制御装置の起動時の同期運転が終了した後の定常運転においてのみ実行され、前記同期運転時の最後の前記位置信号の前記レベルを、前記定常運転の開始後の最初の前記第１の時点以前の前記レベルたる初期値として規定するものである。
【００２０】
請求項２に記載の発明は、請求項１に記載のブラシレスＤＣモータ駆動制御方法であって、前記パルス幅の検出は、その直前に検出された前記パルス幅のｘ倍からｙ倍の期間（０＜ｘ＜ｙ＜１）が経過するまでの間の前記遷移を無視して行われるものである。
【００２１】
請求項３に記載の発明は、ブラシレスＤＣモータの回転子と固定子との相対的な回転位置に応じてレベルが切り換わる位置信号に基づいた電圧パターンを与えるブラシレスＤＣモータ駆動制御装置において、前記位置信号に現れる遷移を検知した第１の時点から所定の遅延時間が経過した第２の時点において前記レベルを検出する工程を前記第１の時点を更新しつつ繰返し、前記第１の時点の更新の度に、その前後で前記レベルが反転しているか否かを確認するパルス反転確認手段と、当該パルス反転確認手段により反転していると確認できた場合に、最新に検知された遷移をリーディングエッジとするパルスのパルス幅に基づいて速度演算を行う一方、前記パルス反転確認手段により反転していない旨を確認した場合に、最新に検知された遷移をリーディングエッジとするパルスを無視して速度演算を行う速度演算部と、当該速度演算部での速度演算結果に基づいて前記電圧パターンを制御するための所定の制御信号を出力する信号出力部とを備えるものである。
【００２２】
そして当該ブラシレスＤＣモータ駆動制御装置は、当該ブラシレスＤＣモータ駆動制御装置の起動時にかかる同期運転についての同期運転モードと、同期運転が終了した後の定常運転にかかる定常運転モードとを切換えるモード切換手段と、前記モード切換手段によって前記同期運転モードに切換えられているときに前記速度演算部に同期運転のための指示を与える同期運転指示手段とをさらに備え、前記パルス反転確認手段は前記モード切換手段によって前記定常運転モードに切換えられたときにのみ作動するようにされ、前記同期運転指示手段は、前記同期運転時の最後の前記位置信号の前記レベルを、前記定常運転の開始後の最初の前記第１の時点以前の前記レベルたる初期値として規定するようにされたものである。
【００２３】
【作用】
請求項１及び請求項３に記載の発明では、位置信号に現れる遷移を検知する第２の時点から所定の遅延時間が経過した第２の時点で、位置信号のレベルを検出する。これを第１の時点の更新毎に繰返し、更新の前後でレベルが反転していなければ、最新に検知された遷移がノイズであるものと判断してこれを無視する一方、反転していれば、最新に検知された遷移が正規な位置信号のパルスのリーディングエッジであると判断して、当該パルスのパルス幅に基づいて電圧パターンを制御する。これにより、所定の遅延時間より短いパルス幅のノイズを全てキャンセルすることができるので、ブラシレスＤＣモータの誤動作を防止できる。
【００２４】
そしてブラシレスＤＣモータ駆動制御装置の起動時における同期運転中は、所定の一般的な方式等に従って駆動制御するものとし、同期運転が終了した後の定常運転時においてのみ上記のようなノイズを無視する動作を行う。この場合において、位置信号について同期運転時の最後のパルスのレベルを、定常運転の開始時における最初のパルスのレベルの初期値として規定しているので、同期運転から定常運転におけるノイズ無視動作への移行を効率よく行うことができる。
【００２５】
請求項２に記載の発明では、請求項１に記載の発明の動作に並行して、位置信号の各パルス中の一部の期間については、一切のパルス変動の認識を無視しているので、前述の所定の遅延時間より短いパルス幅のノイズだけでなく、これよりパルス幅の長いノイズをも全てキャンセルすることができる。よって、ブラシレスＤＣモータの誤動作を、より確実に防止できる。この場合、請求項１に記載の発明によって短いパルス幅のノイズを無視した結果の正規の位置信号の遷移と判断された時点を基準に、ノイズを一切のパルス変動の認識を無視する期間を規律できるので、ノイズを無視する期間を正確に規律することができる。
【００２６】
【発明の実施の形態】
一般に、マイクロコンピュータ（以下単にマイコンと略称する）を用いて所定の処理を行う場合、所定の周期を有するクロック信号に規律されながら様々な演算動作及び信号入出力動作が行われる。したがって、マイコンにおいて所定の信号入力を契機として所定の割込処理を行うような場合、クロック信号の周期、他の割込み処理及びレジスタ退避等の原因により、信号入力時点から一定の「遅延時間」が経過した後に所定の割込処理が完了することになる。この発明は、このような「遅延時間」の発生を利用して、この遅延時間内に発生したノイズをキャンセルしようとするものである。以下、添付図面に基づいてこの発明の一の実施の形態を詳細に説明する。
【００２７】
この実施の形態のブラシレスＤＣモータ駆動制御装置は、図１の如く、マイコンの位置信号Ｓｉｎｔの入力ポートに信号のトレイリングエッジｔｅ１，ｔｅｄ，ｔｅ２，ｔｅ３，…またはリーディングエッジｌｅ１，ｌｅ２，ｌｅｄ，ｌｅ３，…が入力される度に、そのときの位置信号Ｓｉｎｔの各パルスについてのレベルすなわちハイ／ロー状態α１，α２，αｄ１，α３，α４，α５，αｄ２，α６，…を検出し、前回に検出した位置信号パルスのハイ／ロー状態に対して正常に反転しているか否かを判断することで、位置信号Ｓｉｎｔの入力ポートに入力された信号のトレイリングエッジｔｅ１，ｔｅｄ，ｔｅ２，ｔｅ３，…またはリーディングエッジｌｅ１，ｌｅ２，ｌｅｄ，ｌｅ３，…が正規の位置信号によるものであるかあるいはノイズによるものであるかを判別し、ノイズによるものであると判別した場合には当該トレイリングエッジｔｅｄまたはリーディングエッジｌｅｄにかかる信号をキャンセルするものである。なお、この実施の形態では、前述の提案例におけるノイズキャンセルをも併せて実行している。
【００２８】
図２はこの発明のブラシレスＤＣモータ駆動制御装置の一の実施の形態を示すブロック図である。すなわち、このブラシレスＤＣモータ駆動制御装置は、複数極の永久磁石を有する回転子１０と、３相Ｙ結線された電機子コイル１ａ，１ｂ，１ｃを有する固定子１とからなるブラシレスＤＣモータ１１を駆動制御するためのものであって、電機子コイル１ａ，１ｂ，１ｃに対する回転子１０の相対的な回転位置を検出する回転位置検出器２と、回転位置検出器２からの回転子１０の回転位置を表す位置信号Ｓｉｎｔを受けて電機子コイル１ａ，１ｂ，１ｃに対する電圧パターンを切り換えるマイコン４と、マイコン４からのスイッチング信号を受けて、電機子コイル１ａ，１ｂ，１ｃの電圧パターンを切り換え制御する転流制御信号を出力するドライブ回路５と、ドライブ回路５からの転流制御信号を受けて、電機子コイル１ａ，１ｂ，１ｃの電圧パターンを切り換えるインバータ部６とを有している。
【００２９】
回転位置検出器２は、電機子コイル１ａ，１ｂ，１ｃに並列状態で３相結線された抵抗２１ａ，２１ｂ，２１ｃからなる抵抗回路２１と、抵抗回路２１の中性点Ｍの電圧Ｖ_MNを積分し且つ増幅する積分増幅回路２２と、この積分増幅回路２２からの積分信号Ｉｎｔをパルス化するパルス化回路２３とを有している。
【００３０】
ここで、積分増幅回路２２は、増幅器ＩＣ１の反転入力端子に抵抗回路２１の中性点Ｍの電圧Ｖ_MNを入力するとともに、非反転入力端子にグランドＧＮＤを接続し、出力端子と反転入力端子との間に抵抗Ｒ１とコンデンサＣ１とを並列に接続してなる。すなわち、電機子コイル１ａ，１ｂ，１ｃの中性点Ｍは、グランドＧＮＤを介して増幅器ＩＣ１の非反転入力端子に接続されているので、積分増幅回路２２は、抵抗回路２１の中性点Ｍの電圧と電機子コイル１ａ，１ｂ，１ｃの中性点Ｎの電圧との電位差を表す電位差信号Ｖ_MNを検出するとともに、電位差信号Ｖ_MNを積分して、積分信号Ｉｎｔを出力する。
【００３１】
また、パルス化回路２３は、増幅器ＩＣ２とフォトカプラＰＣとを有するものである。このうち増幅器ＩＣ２では、積分増幅回路２２からの積分信号Ｉｎｔを反転入力端子に入力するとともに、増幅器ＩＣ２の非反転入力端子が抵抗Ｒ２を介してグランドＧＮＤに接続され、抵抗Ｒ３，Ｒ４によってプルアップされている。さらに増幅器ＩＣ２の出力端子と非反転入力端子との間でフォトカプラＰＣの発光部ＰＣａと抵抗Ｒ３が順次直列に接続されている。抵抗Ｒ４は発光部ＰＣａと抵抗Ｒ３の接続点をプルアップしている。また、フォトカプラＰＣは、強電部と弱電部との間の電気的絶縁を確保したままで位置信号Ｓｉｎｔをマイコン４に供給するためのものであり、フォトカプラＰＣの受光部ＰＣｂと抵抗Ｒ５とが所定の電圧間で直列に接続され、この接続点の信号がマイコン４に供給されている。なお、増幅器ＩＣ２及び抵抗Ｒ２〜Ｒ４は零クロスコンパレータを構成している。
【００３２】
マイコン４は、ＣＰＵ、ＲＯＭ及びＲＡＭ等を備える一般的なものであって、その演算または制御動作はすべてＲＯＭ等に予め格納されたソフトウェアによって実行されるものである。このマイコン４の機能要素としては、回転位置検出器２から与えられる位置信号Ｓｉｎｔの状態に応じて初期運転としての同期運転モードと正規運転としての位置検出運転モード（定常運転モード）とに設定切換えするモード切換手段３１と、モード切換手段３１により同期運転モードに設定された場合に同期運転の指示を与える同期運転指示手段３２と、モード切換手段３１により位置検出運転モードに設定された場合に位置信号Ｓｉｎｔのパルスの正常なハイ／ロー反転状態を確認するパルス反転確認手段３３と、パルス反転確認手段３３により正常なハイ／ロー反転状態が確認できた場合にのみ各パルス単位毎にそのハイ／ロー状態のパルス幅Ｔ（図１０参照）を測定するＴ測定部３４と、操作パネル等の外部の入力手段３５から与えられる目標パルス幅Ｔｘ（図１０参照）をマイコン４内に受入れる目標Ｔｘ入力部３６と、Ｔ測定部３４で検出したパルス幅Ｔと目標Ｔｘ入力部３６で受入れた目標パルス幅Ｔｘとの差に応じて望ましい回転速度を演算する速度演算部３７と、速度演算部３７での演算結果に応じて望ましいインバータ電圧Ｖを決定するインバータ電圧Ｖ決定部３８と、望ましい回転速度及びインバータ電圧Ｖに基づいて適正なＰＷＭパルス波を変調生成するＰＷＭ変調部３９と、ＰＷＭパルス波に基づいて適正なスイッチング信号をドライブ回路５へ出力するインバータ波形信号出力部４０とを備えている。
【００３３】
インバータ部６は、図８に示すインバータ部６０と同様の構成であるため、詳細な説明を省略する。
【００３４】
以上の構成において、ブラシレスＤＣモータが位置検出に従って駆動されているとき、電機子コイル１ａ，１ｂ，１ｃの各Ｕ相、Ｖ相、Ｗ相の誘起電圧Ｅ_U，Ｅ_V，Ｅ_Wは、図３（Ａ）〜（Ｃ）に示すように、１２０ｄｅｇ毎に位相の異なる台形状の波形となる。そして、図２に示す回転位置検出器２の増幅器ＩＣ１は、反転入力端子に入力された抵抗回路２１の中性点Ｍの電圧と、増幅器ＩＣ１の非反転入力端子に入力された電機子コイル１ａ，１ｂ，１ｃの中性点Ｎの電圧Ｖ_Nとの電位差を表す電位差信号Ｖ_MN（図３（Ｄ））を検出するとともに、その電位差信号を積分して、積分信号Ｉｎｔ（図３（Ｅ））を出力する。この積分信号Ｉｎｔは、回転周波数の３倍の周波数の略正弦波形となる。そして、パルス化回路２３は、増幅器ＩＣ２の反転入力端子に入力された積分信号Ｉｎｔを所定の振幅に増幅し、その増幅された積分信号ＩｎｔをフォトカプラＰＣにて光電変換して整形し、位置信号Ｓｉｎｔ（図３（Ｆ））として出力する。
【００３５】
次に、回転位置検出器２からの位置信号Ｓｉｎｔは、マイコン４の割込端子３０からモード切換手段３１に入力される。ここで、まずブラシレスＤＣモータ駆動制御装置の起動時には、図４の如く、回転子１０の回転数は停止状態から徐々に増大するため、マイコン４に与えられる位置信号Ｓｉｎｔのパルス幅Ｔは安定状態Ｓ１に至るまでは徐々に短く（すなわち速く）なるよう変化する。このため、マイコン４内のモード切換手段３１は、ブラシレスＤＣモータ駆動制御装置の起動後暫くの間は同期運転モードを設定する。すなわち、図５中のステップＳ１１において、まず位置信号Ｓｉｎｔの各パルスがハイ状態であるかロー状態であるかを示す変数「Ｐｏｒｔｂｕｆ」を初期設定した後、位置信号Ｓｉｎｔが割込端子３０に入力される毎にそのパルス幅Ｔを検出し（ステップＳ１２）、このときのパルス幅Ｔをスタックに記憶する（ステップＳ１３）。この際、モード切換手段３１で同期運転モードに設定された同期運転指示手段３２は、まず同期運転である旨の信号を速度演算部３７に与え、このときの信号に基づいてインバータ電圧Ｖ決定部３８により望ましいインバータ電圧Ｖを決定して望ましい回転速度及びインバータ電圧Ｖが得られる。その後、ＰＷＭ変調部３９によって積分値正弦波状になるようＰＷＭ変調が行われ、ここで得られたＰＷＭパルス状のスイッチング信号をインバータ波形信号出力部４０を通じてドライブ回路５５へ出力する。このような動作によって得られたスイッチング信号に基づいて、インバータ部６は、ブラシレスＤＣモータ１１の回転子１０の回転数が所定のレベルに安定するまで同期運転を続ける。なお、この同期運転モードにおけるインバータ駆動は、一般的なＶ／Ｆ一定制御方式に従って駆動制御すればよいため、その詳細な動作説明は省略する。
【００３６】
同期運転がされている間も、マイコン４のモード切換手段３１は、ハイ／ロー状態で繰返し入力される位置信号Ｓｉｎｔのパルス幅Ｔを検出しつづける。複数回（例えば４回）連続して入力された位置信号Ｓｉｎｔのパルス幅Ｔが全て同一になった時点で（ステップＳ１４）、回転子１０の回転数が安定状態Ｓ１（図４）に至った旨を判断し、同期運転を完了させる動作に移る。このときの位置信号Ｓｉｎｔのパルスがハイ状態であるかロー状態であるかを示す変数「ポートＳｉｎｔ」を前述した変数「Ｐｏｒｔｂｕｆ」に代入する（ステップＳ１５）。
【００３７】
同期運転の完了後は、具体的には、モード切換手段３１が同期運転モードから位置検出運転モードに切換えることで実現される。この時点で、同期運転指示手段３２は機能を停止する。なお、前述のステップＳ１５で説明した通り、変数「Ｐｏｒｔｂｕｆ」には、位置検出運転時の初期値として、同期運転モードにおける最後の位置信号Ｓｉｎｔのパルスのハイ／ロー状態が代入されている。
【００３８】
次に、同期運転完了後の位置検出運転モードの動作について説明する。マイコン４のパルス反転確認手段３３は、図６の如く、まずステップＳ２１において、割込端子３０を通じて割込入力された位置信号Ｓｉｎｔのパルス遷移（トレイリングエッジ及びリーディングエッジ）を検出した直後の位置信号Ｓｉｎｔのパルスがハイ状態であるかロー状態であるかを検出し、これを変数「ポートＳｉｎｔ」に代入する。そして、この変数「ポートＳｉｎｔ」が、既に規定されている前回値としての変数「Ｐｏｒｔｂｕｆ」に対して一致しているかどうかを比較判断する（ステップＳ２２）。
【００３９】
ここで、マイコン４を用いて所定の処理を行う場合、所定の周期を有するクロック信号に規律されながら様々な演算動作及び信号入出力動作が行われる。したがって、マイコン４に対して割込入力した信号を契機として所定の割込処理を行うような場合、この割込処理はクロック信号に同期して実行されるので、クロック信号の周期、他の割込み処理及びレジスタ退避等の原因によって、信号入力時点から一定の「遅延時間」が経過した後に所定の割込処理が完了することになる。したがって、上述のステップＳ２１の処理が行われた後、一定の「遅延時間」が経過した後にステップＳ２２の処理が行われることになる。すなわち、図７の如く、位置信号Ｓｉｎｔにパルス遷移ｌｅ，ｔｅｄ，ｔｅが順に検出されても（ステップＳ２１）、それぞれのパルス遷移ｌｅ，ｔｅｄ，ｔｅの直後αにおける位置信号Ｓｉｎｔのパルスのハイ／ロー状態を検出する（ステップＳ２２）までには遅延時間ΔＴが発生する。ここで、位置信号Ｓｉｎｔにノイズが重畳したとき、このノイズはパルス遷移ｔｅｄに始って極めて短い幅のパルス波となって現れることになる。したがって、ノイズのパルス幅が遅延時間ΔＴよりも短ければ、ステップＳ２１においてノイズをパルス遷移ｔｅｄとして検出してしまったとしても、その次のステップＳ２２においてパルスのハイ／ロー状態を検出する時点では、位置信号Ｓｉｎｔはノイズ状態から定常状態に復帰していることになる。すなわち、図１中の時点Ｔｎ２において、リーディングエッジｌｅ１を検出して（ステップＳ２１）そのときに入力されたパルスがα２のようにハイ状態である旨を確認（ステップＳ２２）した後、次に時点Ｔｎｄ１において極めて短いパルス幅のノイズが混入してそのトレイリングエッジｔｅｄが現れた場合（ステップＳ２１）、その直後にパルスのハイ／ロー状態を検出したとき（ステップＳ２２）にαｄ１がハイ状態になっていることになる。また同様にして、図１中の時点Ｔｎ５において、トレイリングエッジｔｅ３を検出して（ステップＳ２１）そのときに入力されたパルスがα５のようにロー状態である旨を確認（ステップＳ２２）した後、次に時点Ｔｎｄ２において極めて短いパルス幅のノイズが混入してそのリーディングエッジｌｅｄが現れた場合（ステップＳ２１）、その直後にステップＳ２２としてパルスのハイ／ロー状態を検出したときにαｄ２がハイ状態になっていることになる。
【００４０】
このように、ステップＳ２２において、α２（すなわち前回値「Ｐｏｒｔｂｕｆ」）とαｄ１（すなわち今回値「ポートＳｉｎｔ」）が一致している場合には、今回入力されたパルス遷移がノイズによるものであると判断できることになる。したがって、一致していると判断した場合は、このようなノイズに基づいてインバータ制御を行うことは好ましくないため、既に速度演算部３７、インバータ電圧Ｖ決定部３８、ＰＷＭ変調部３９及びインバータ波形信号出力部４０を通じて規定されたインバータの定常運転を単に続行しながら、再びステップＳ２１の割込処理を待つことにする。なお、ステップＳ２１からステップＳ２２に至るまでの遅延時間ΔＴは通常数μｓであることが判っている。このため、数μｓ未満のパルス幅のノイズは全てキャンセルできることになる。
【００４１】
また、高性能なマイコンを用い、この数μｓの遅延が生じない場合にはソフト的にＮＯＰ命令などを使って遅延を作ればこの数μｓの時間を何μｓに設定するかをコントロールできる。
【００４２】
一方、ステップＳ２２において、前回値「Ｐｏｒｔｂｕｆ」と今回値「ポートＳｉｎｔ」とが一致していないと判断した場合には、今回入力されたパルスがノイズによるものではなく正規の位置信号Ｓｉｎｔのパルスであることになる。
【００４３】
この場合、ステップＳ２３において、まず今回値である「ポートＳｉｎｔ」を次回に前回値として使用するために「Ｐｏｒｔｂｕｆ」に代入しておく。
【００４４】
次に、ステップＳ２４において、今回入力された位置信号Ｓｉｎｔのパルス幅Ｔ（図１０）をＴ測定部３４で検出する。一方、操作パネル等の外部の入力手段３５から与えられる目標パルス幅Ｔｘ（図１０）を目標Ｔｘ入力部３６を通じてマイコン４内に受入れる。そして、Ｔ測定部３４で検出したパルス幅Ｔと目標Ｔｘ入力部３６で受入れた目標パルス幅Ｔｘとを大小比較し（ステップＳ２５）、その比較結果に応じて速度演算部３７は望ましい回転速度を演算する。また、速度演算部３７での演算結果に応じて、望ましいインバータ電圧Ｖをインバータ電圧Ｖ決定部３８により決定する（ステップＳ２６，Ｓ２７）。なお、このとき回転速度の演算及びインバータ電圧Ｖの決定においては、図３（Ｇ）のように所定の位相補正を併せて行っておく。そして、ＰＷＭ変調部３９によって積分値正弦波状になるようＰＷＭ変調を施し、ここで得られたＰＷＭパルス状のスイッチング信号をインバータ波形信号出力部４０を通じてドライブ回路５へ出力する（ステップＳ２８）。
【００４５】
ドライブ回路５は、マイコン４からのスイッチング信号を受けて、インバータ部６の各トランジスタ６ａ〜６ｆのベースに転流制御信号を出力する。そして、インバータ部６の各トランジスタ６ａ〜６ｆは、図３（Ｈ）〜（Ｍ）のように順次オンオフして、電機子コイル１ａ，１ｂ，１ｃに対する電圧パターンを切り換える。かかる電圧パターンの切り換え処理は、図１０のようにマイコン４によって検出されるパルス幅Ｔが目標パルス幅Ｔｘに等しくなると判断された時点Ｔｍ１まで行われ、その後はこの目標パルス幅Ｔｘをパルス幅Ｔとしてインバータ部６によるブラシレスＤＣモータの定常駆動が続行される。
【００４６】
また、以上の動作に並行して、図１２（Ｂ）に示した提案例における処理、すなわち、位置信号Ｓｉｎｔにおける前回パルスのパルス幅Ｔ_n-1に対し「（１／２）×Ｔ_n-1」から「（３／４）×Ｔ_n-1」の時点Ｔｍ３までの間は、一切の信号変化を受付けないようにし、この部分についてパルス幅の長いノイズをもキャンセルしておく。ただし、このときの「（１／２）×Ｔ_n-1」及び「（３／４）×Ｔ_n-1」といった期間の起点は、図６中のステップＳ２２において「ポートＳｉｎｔ」が前回パルスの「Ｐｏｒｔｂｕｆ」に一致しておらず正規の位置信号Ｓｉｎｔのパルス遷移であると判断された当該パルス遷移の入力時点とすればよい。これにより、提案例のような処理においてもノイズによる影響を排除できる。
【００４７】
このようにして、提案例におけるノイズキャンセル処理に加え、さらに位置信号Ｓｉｎｔの各パルスの入力時においてそれぞれのパルス遷移を検出してその直後にパルスのハイ／ロー状態を検出するまでの間に遅延時間ΔＴが発生することを利用して、この遅延時間ΔＴに満たないパルス幅のノイズを全てキャンセルすることができるので、マイコン４、ドライブ回路５及びインバータ部６の誤動作やインバータ停止等の事態を防止できる。
【００４８】
なお、上記の実施の形態では、積分信号Ｉｎｔに基づいて位置信号Ｓｉｎｔから電圧パターンを切り換えるまでの時間を調整していたが、この積分信号Ｉｎｔに代えて、回転位置検出器２内の抵抗回路２１の中性点に基づく電位差信号をそのまま採用することも可能である。
【００４９】
【発明の効果】
請求項１及び請求項３に記載の発明によれば、位置信号に現れる遷移を検知する第２の時点から所定の遅延時間が経過した第２の時点で、位置信号のレベルを検出し、これを第１の時点の更新毎に繰返し、更新の前後でレベルが反転していなければ、最新に検知された遷移がノイズであるものと判断してこれを無視する一方、反転していれば、最新に検知された遷移が正規な位置信号のパルスのリーディングエッジであると判断して、当該パルスのパルス幅に基づいて電圧パターンを制御するので、所定の遅延時間より短いパルス幅のノイズを全てキャンセルすることができる。したがって、ブラシレスＤＣモータの誤動作を防止できる。
【００５０】
そしてブラシレスＤＣモータ駆動制御装置の起動時における同期運転中は、所定の一般的な方式等に従って駆動制御するものとし、同期運転が終了した後の定常運転時においてのみ上記のようなノイズを無視する動作を行う場合において、位置信号について同期運転時の最後のパルスのレベルを、定常運転の開始時における最初のパルスのレベルの初期値として規定しているので、同期運転から定常運転におけるノイズ無視動作への移行を効率よく行うことができる。
【００５１】
請求項２に記載の発明によれば、請求項１に記載の発明の動作に並行して、位置信号の各パルス中の一部の期間については、一切のパルス変動の認識を無視しているので、前述の所定の遅延時間より短いパルス幅のノイズだけでなく、これよりパルス幅の長いノイズをも全てキャンセルすることができる。よって、ブラシレスＤＣモータの誤動作を、より確実に防止できる。この場合、請求項１に記載の発明によって短いパルス幅のノイズを無視した結果の正規の位置信号の遷移と判断された時点を基準に、ノイズを一切のパルス変動の認識を無視する期間を規律できるので、ノイズを無視する期間を正確に規律することができる。
【００５２】
以上のことから、ノイズによる影響を殆ど受けずに済むブラシレスＤＣモータ駆動制御方法及びその装置を提供できる。
【図面の簡単な説明】
【図１】マイコンに与えられる位置信号にノイズが重畳した様子を示す信号波形図である。
【図２】この発明の一の実施の形態のブラシレスＤＣモータ駆動制御装置を示すブロック図である。
【図３】ブラシレスＤＣモータ駆動制御装置の各部の信号波形を示す図である。
【図４】ブラシレスＤＣモータ駆動制御装置の起動時の同期運転及びその後の位置検出運転における回転子の回転数の変化を示す図である。
【図５】この発明の一の実施の形態における同期運転動作を示すフローチャートである。
【図６】この発明の一の実施の形態における位置検出運転動作を示すフローチャートである。
【図７】マイコンに位置信号が与えられてから位置信号の各パルスのハイ／ロー状態を検出するまでに生じる遅延時間を示す図である。
【図８】従来のブラシレスＤＣモータ駆動制御装置を示すブロック図である。
【図９】マイコン内におけるインバータ制御の動作を示すフローチャートである。
【図１０】マイコンに与えられる位置信号を示す波形図である。
【図１１】ブラシレスＤＣモータの運転周波数とトルクとの関係を示す図である。
【図１２】マイコンに与えられる位置信号を示す拡大波形図である。
【符号の説明】
１ 固定子、１ａ，１ｂ，１ｃ 電機子コイル、２ 回転位置検出器、３ レベル検出器、４ マイコン、５ ドライブ回路、６ インバータ部、６ａ〜６ｆトランジスタ、７ 電流センサ、１０ 回転子、１１ ブラシレスＤＣモータ、２１ 抵抗回路、２１ａ，２１ｂ，２１ｃ 抵抗、２２ 積分増幅回路、２３パルス化回路、３１ 周期演算部、３２ 演算部、３３ インバータモード選択部、３４ 速度演算部、３５ 速度制御部、４１ レベル判定部、４２ ＰＷＭ部、Ｔ１ 位相補正タイマ、Ｔ２ 周期測定タイマ、４５ 電流変化判別手段、４６ 停止指示手段、ＡＮ０，ＡＮ１，ＡＮ２ アナログ入力端子、Ｉｕ，Ｉｖ，Ｉｗ 電流、Ｓｉｎｔ 位置信号[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a brushless DC motor drive control method and apparatus, and more specifically, represents the relative positions of a rotor and a stator based on an induced voltage induced in an armature coil of a brushless DC motor. The present invention relates to a brushless DC motor drive control method and apparatus for detecting a position signal and controlling a voltage pattern of an armature coil based on the position signal.
[0002]
[Prior art]
Brushless DC motors are generally diversified in various fields because they can improve the use restriction due to commutation sparks caused by the mechanical commutator of a general DC motor, maintainability, and environmental resistance. Reference numeral 50 in FIG. 8 denotes a rotor having a plurality of permanent magnets in a brushless DC motor, and reference numeral 51 denotes a stator having armature coils 51a, 51b, and 51c similarly connected in a three-phase Y connection.
[0003]
As shown in FIG. 8, the conventional brushless DC motor drive control device for driving such a brushless DC motor first determines the relative rotational position of the rotor 50 with respect to the armature coils 51a, 51b, 51c as a rotational position detector 53. Detect with. Then, a position signal Sint indicating the rotation position of the rotor 50 is given from the rotation position detector 53 to a microcomputer (hereinafter abbreviated as a microcomputer) 54, and the microcomputer 54 sends a drive circuit 55 to the drive circuit 55 based on the position signal Sint. A predetermined switching signal is given. As a result, based on the commutation control signal output from the drive circuit 55, the inverter unit 60 switches the voltage pattern of the armature coils 51a, 51b, 51c.
[0004]
Here, the inverter unit 60 includes three transistors 60a, 60b, and 60c connected to the positive side of the DC power source 56, and three transistors 60d, 60e, and 60f connected to the negative side of the DC power source 56, respectively. It is configured. The emitter of the transistor 60a and the collector of the transistor 60d are connected to each other, the emitter of the transistor 60b and the collector of the transistor 60e are connected to each other, and the emitter of the transistor 60c and the collector of the transistor 60f are connected to each other. The connection intermediate point between the transistors 60a and 60d is connected to the U-phase armature coil 51a, the connection intermediate point between the transistors 60b and 60e is connected to the V-phase armature coil 51b, and the transistors 60c and 60f are connected to each other. A W-phase armature coil 51c is connected to the connection midpoint. A commutation control signal from the drive circuit 55 is input to the bases of the transistors 60a to 60f. Each of these transistors 60a to 60f is an insulated gate transistor (IGBT) element that is inexpensive and can be downsized.
[0005]
In the rotational position detector 53, first, the three resistors 61a, 61b, 61c of the resistor circuit 61 are connected in parallel to correspond to the armature coils 51a, 51b, 51c. 61 neutral point voltage V _M And the voltage V at the neutral point of the armature coils 51a, 51b, 51c. _N (Potential difference signal V indicating the potential difference from the ground potential here) _MN Is integrated by the integrating amplifier circuit 62. The integral signal Int from the integral amplifier circuit 62 is waveform-shaped by the zero cross comparator 63 and then applied to the photocoupler 64. The square wave signal output from the photocoupler 64 is converted into the armature of the stator 51. The position signal Sint indicating the relative position of the rotor 50 with respect to the coils 51a, 51b, 51c is output to the microcomputer 54.
[0006]
Further, the microcomputer 54 sets the one-time high state and the one-low state to one pulse unit for each square unit of the square-wave position signal Sint given from the rotational position detector 53 through the interrupt terminal 70. Further, a T measurement unit 71 that measures the pulse width T (FIG. 10) in the high state or the low state and a target pulse width Tx (FIG. 10) given from an external input means 72 such as an operation panel are received in the microcomputer 54. A target Tx input unit 73; a speed calculation unit 74 that calculates a desired rotation speed according to a difference between the pulse width T detected by the T measurement unit 71 and the target pulse width Tx received by the target Tx input unit 73; An inverter voltage V determination unit 75 that determines a desired inverter voltage V according to a calculation result in the unit 74, and an appropriate value based on the desired rotation speed and the inverter voltage V. Such a PWM modulation unit 76 for the PWM pulse wave modulation generated, and an inverter waveform signal output unit 77 that outputs to the drive circuit 55 a proper switching signal based on the PWM pulse wave.
[0007]
In such a brushless DC motor drive control device, each U-phase, V-phase, and W-phase motor terminal voltage from the inverter 60 is set to V. _U , V _V , V _W And the induced voltages of the U-phase, V-phase, and W-phase of the armature coils 51a, 51b, 51c are respectively E _U , E _V , E _W Then, the voltage V at the neutral point of the resistance circuit 61 _M And the voltage V at the neutral point of the armature coils 51a, 51b, 51c _N And
V _M = (1/3) (V _U + V _V + V _W )
V _N = (1/3) {(V _U -E _U ) + (V _V -E _V ) + (V _W -E _W )}
It becomes. Therefore, the potential difference signal V representing the potential difference between the neutral point of the resistance circuit 61 and the neutral point of the armature coils 51a, 51b, 51c. _MN Is
V _MN = V _M -V _N = (1/3) (E _U + E _V + E _W )
The induced voltage of the armature coils 51a, 51b, 51c is E _U , E _V , E _W It can be seen that it is proportional to the sum of.
[0008]
Here, the induced voltage E of the armature coils 51a, 51b, 51c _U , E _V , E _W Becomes a trapezoidal waveform with a different phase every 120 degrees, and the potential difference signal V _MN Is the induced voltage E _U , E _V , E _W Is a substantially triangular wave having a fundamental wave frequency component that is three times that of. This potential difference signal V _MN The peak point of the triangular wave is the voltage pattern switching point. This potential difference signal V _MN Since the amplitude of the peak point of fluctuates according to the rotation speed, the potential difference signal V from the integration amplifier circuit 62 is generated by the integration amplifier circuit 62. _MN Is a substantially sinusoidal integral signal ∫V _MN After the integral conversion to dt, the zero cross comparator 63 detects and amplifies the zero cross point of the integrated signal Int, and after the photocoupler 64 converts it to a square wave, the position signal Sint is output to the microcomputer 54.
[0009]
Next, in the microcomputer 54, as shown in FIG. 9, after receiving the square wave position signal Sint from the rotational position detector 53 at the interrupt terminal 70 (step S01), one high state and one time The low state is set to one pulse unit, and the pulse width T (FIG. 10) of the high state or the low state is detected by the T measuring unit 71 for each pulse unit (step S02). On the other hand, the target pulse width Tx (FIG. 10) given from the external input means 72 such as an operation panel is received in the microcomputer 54 through the target Tx input unit 73. Then, the pulse width T detected by the T measurement unit 71 and the target pulse width Tx received by the target Tx input unit 73 are compared in magnitude (step S03), and the speed calculation unit 74 determines a desired rotational speed according to the comparison result. Calculate. Further, a desired inverter voltage V is determined by the inverter voltage V determination unit 75 according to the calculation result in the speed calculation unit 74. After the desired rotation speed and the inverter voltage V are obtained in this way, the PWM modulation unit 76 performs PWM modulation so as to obtain an integral sine wave shape, and the obtained PWM pulse-like switching signal is converted into an inverter waveform signal output unit. 77 to the drive circuit 55.
[0010]
The drive circuit 55 receives a switching signal from the microcomputer 54 and outputs a commutation control signal to the bases of the transistors 60 a to 60 f of the inverter unit 60. And each transistor 60a-60f of the inverter part 60 is turned on / off sequentially, and the voltage pattern with respect to the armature coils 51a, 51b, 51c is switched (steps S04-S06).
[0011]
Thus, the brushless DC motor uses the induced voltage of the armature coils 51a, 51b, 51c as E. _U , E _V , E _W Thus, the position signal Sint representing the rotational position of the rotor 50 is output, and the inverter unit 60 switches the voltage pattern of the armature coils 51a, 51b, 51c according to the position signal Sint. The voltage pattern switching process is performed until time Tm1 when it is determined that the pulse width T detected by the microcomputer 54 is equal to the target pulse width Tx as shown in FIG. 10, and thereafter, the target pulse width Tx is changed to the pulse width Tx. As a result, the steady drive of the brushless DC motor by the inverter unit 60 is continued.
[0012]
As described above, when a load having a large torque fluctuation range such as a compressor of various air conditioners is driven using a brushless DC motor driven and controlled by a brushless DC motor drive control device, the performance of the brushless DC motor is If the above is sufficiently exhibited, effective operation is possible within the operating area required for the compressor, for example, within the range of the maximum pressure limit, the limit at the inverter maximum voltage and the maximum frequency limit as shown in FIG.
[0013]
[Problems to be solved by the invention]
In a general brushless DC motor drive control device, as is apparent from FIG. 8, the relative rotation position of the rotor 50 with respect to the armature coils 51a, 51b, 51c is detected by a signal from the high voltage section of the inverter section 60. Therefore, the position signal Sint or the like has a structure in which noise is easily superimposed. When sudden and large noise is generated, the discrimination and control in the microcomputer 54 is abnormal. As a result, the phase of the inverter current waveform is suddenly shifted, the amplitude of the inverter current waveform increases rapidly, and an overcurrent flows through the inverter unit 60 before long. As a result, the inverter control becomes impossible and the brushless DC motor stops, and in the worst case, the inverter unit 60 or its peripheral parts may be overheated or destroyed. Therefore, it is important to reduce the influence of noise in the position signal Sint.
[0014]
In view of such circumstances, in order to reduce the influence of noise as much as possible, in the microcomputer 54, by ignoring the signal change of the predetermined portion within each pulse width T of each pulse of the position signal Sint, this predetermined portion The proposal (FIGS. 12A and 12B) to cancel the noise is made. In this proposed example, specifically, as shown in FIG. 12A, each time the leading edge and trailing edge of the high state of the position signal Sint are given to the microcomputer 54, the high state of each position signal Sint. And the pulse width T is continuously detected for the low state. Here, assuming that the detected value of the nth pulse width T is Tn, the value of the pulse width T detected by the microcomputer 54 is “. _n-1 , T _n , T _{n + 1} , ... ". However, when the inverter is driven, the pulse width T may change from moment to moment. _n-1 "And" T _n "And" T _{n + 1} Does not necessarily match. Therefore, if it is now in the middle of the pulse reception state of the nth position signal Sint, the value T of the pulse width T of the nth pulse of the position signal Sint at this time _n Is not necessarily the previous value T _n-1 As shown in FIG. 12A, the microcomputer 54 cannot recognize unless the time Tm2 elapses. However, in normal inverter driving, the pulse width T (..., T _n-1 , T _n , T _{n + 1} ,...) Is relatively gradual, and the difference between the pulse width T of one pulse and the pulse width T of the next pulse following it is never more than 25%. That is, the values “..., T of the pulse width T of the position signal Sint given sequentially. _n-1 , T _n , T _{n + 1} , ... "normally satisfies the following conditions.
[0015]

Considering this, as shown in FIG. 12B, in the n-th pulse (low state in FIG. 12B), the value T of the pulse width T _n Even if is unknown at this time, the previous value T _n-1 Is known at this time, the transition of the position signal Sint (in this case, the trailing edge) is set to the origin “0”, and the end edge is recognized as “(3/4) × T _n-1 It is sufficient to go after time Tm3. Therefore, the nth pulse (the value T of the pulse width T in this case) _n Is unknown at this time), after the transition time “0” has elapsed, “(3/4) × T _n-1 During the period up to time Tm3, it is possible to ignore any signal change, and it is possible to cancel the noise in this portion. In FIG. 12B, “(1/2) × T _n-1 "(3/4) x T _n-1 An example of canceling up to time Tm3 is shown.
[0016]
However, even in this proposed example, “(3/4) × T _n-1 When noise enters after time Tm3, it is impossible to cancel the noise. And this “(3/4) × T _n-1 ”Due to noise after time Tm3 _n If this is detected, there is a high possibility of malfunction, which may result in the inverter being stopped.
[0017]
Accordingly, an object of the present invention is to provide a brushless DC motor drive control method and apparatus capable of eliminating the influence of noise of a position signal given to a microcomputer.
[0018]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention described in claim 1 is a brushless DC that provides a voltage pattern based on a position signal whose level is switched according to the relative rotational position of the rotor and stator of the brushless DC motor. In the motor drive control method, a step of detecting the level at a second time point when a predetermined delay time has elapsed from a first time point at which a transition appearing in the position signal is detected while updating the first time point. Repeatedly, if the level is the same before and after each update at the first time point, the latest detected transition is ignored while the latest detected transition is ignored. The voltage pattern is controlled based on the pulse width of a pulse having a leading edge.
[0019]
And the The brushless DC motor drive control method is executed only in the steady operation after the synchronous operation at the start of the brushless DC motor drive control device is completed, and the level of the last position signal in the synchronous operation is set to the steady state. It is defined as the initial value that is the level before the first time point after the start of operation.
[0020]
Claim 2 The invention described in claim 1 In the brushless DC motor drive control method described above, the detection of the pulse width is performed until a period (0 <x <y <1) from x to y times the pulse width detected immediately before the pulse width is detected. It is performed by ignoring the transition between the two.
[0021]
Claim 3 The brushless DC motor drive control device that provides a voltage pattern based on a position signal whose level is switched according to the relative rotational position of the rotor and the stator of the brushless DC motor. The step of detecting the level is repeated while updating the first time point at a second time point when a predetermined delay time has elapsed from the first time point at which the appearing transition is detected, and each time the first time point is updated. The pulse inversion confirmation means for confirming whether or not the level is inverted before and after that, and when it is confirmed that the level is inverted by the pulse inversion confirmation means, the latest detected transition is set as the leading edge While calculating the speed based on the pulse width of the pulse, if the pulse inversion confirmation means confirms that it is not inverted, the latest detected transition is reset. A speed calculation unit that performs speed calculation ignoring a pulse as a ding edge, and a signal output unit that outputs a predetermined control signal for controlling the voltage pattern based on a speed calculation result in the speed calculation unit It is to be prepared.
[0022]
And The brushless DC motor drive control device includes mode switching means for switching between a synchronous operation mode for synchronous operation when the brushless DC motor drive control device is activated and a steady operation mode for steady operation after the completion of the synchronous operation. A synchronous operation instruction means for giving an instruction for synchronous operation to the speed calculation unit when the mode switching means is switched to the synchronous operation mode, and the pulse inversion confirmation means is provided by the mode switching means. The synchronous operation instruction means is operated only when switched to the steady operation mode, and the synchronous operation instruction means sets the level of the last position signal at the time of the synchronous operation to the first value after the start of the steady operation. This is defined as the initial value as the level before the time point 1.
[0023]
[Action]
Claim 1 and claim 3 In the above-described invention, the level of the position signal is detected at a second time point when a predetermined delay time has elapsed from the second time point at which a transition appearing in the position signal is detected. This is repeated for each update at the first time point, and if the level is not reversed before and after the update, it is determined that the latest detected transition is noise and ignored, while if it is reversed The most recently detected transition is determined to be the leading edge of the pulse of the normal position signal, and the voltage pattern is controlled based on the pulse width of the pulse. As a result, it is possible to cancel all noise having a pulse width shorter than the predetermined delay time, and thus it is possible to prevent malfunction of the brushless DC motor.
[0024]
And During synchronous operation at the time of starting the brushless DC motor drive control device, drive control is performed according to a predetermined general method or the like, and only during steady operation after completion of synchronous operation. above The operation which ignores such noise is performed. In this case, the level of the last pulse at the time of synchronous operation is defined as the initial value of the level of the first pulse at the start of steady operation for the position signal. Migration can be done efficiently.
[0025]
Claim 2 In the invention described in claim Invention of 1 In parallel with the above operation, for some period in each pulse of the position signal, since recognition of any pulse fluctuation is ignored, not only noise with a pulse width shorter than the predetermined delay time described above, Any noise with a longer pulse width can be canceled. Therefore, the malfunction of the brushless DC motor can be prevented more reliably. In this case, the claim Invention of 1 Can be used to discriminate the period during which the recognition of any pulse fluctuation is ignored, based on the point when it is determined that the transition of the normal position signal is a result of ignoring the noise with a short pulse width. Can be disciplined.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
In general, when predetermined processing is performed using a microcomputer (hereinafter simply referred to as a microcomputer), various arithmetic operations and signal input / output operations are performed while being regulated by a clock signal having a predetermined period. Therefore, when a predetermined interrupt process is performed in response to a predetermined signal input in the microcomputer, a certain “delay time” from the signal input time point is caused by the clock signal period, other interrupt processes, register saving, etc. After a lapse, the predetermined interrupt process is completed. The present invention intends to cancel the noise generated within this delay time by utilizing the occurrence of such “delay time”. Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.
[0027]
As shown in FIG. 1, the brushless DC motor drive control device according to this embodiment has a signal trailing edge te1, ted, te2, te3,... Or a leading edge le1, le2, led, at the input port of the microcomputer position signal Sint. Each time le3,... is input, the level for each pulse of the position signal Sint at that time, that is, the high / low states α1, α2, αd1, α3, α4, α5, αd2, α6,. By determining whether the detected position signal pulse is normally inverted with respect to the high / low state, the trailing edges te1, ted, te2, te3 of the signal input to the input port of the position signal Sint are determined. ... Or leading edges le1, le2, led, le3,... If it is determined that it is due to noise, a signal applied to the trailing edge ted or the leading edge led is canceled. In this embodiment, noise cancellation in the above-described proposal example is also executed.
[0028]
FIG. 2 is a block diagram showing an embodiment of the brushless DC motor drive control apparatus of the present invention. That is, this brushless DC motor drive control device includes a brushless DC motor 11 including a rotor 10 having permanent magnets having a plurality of poles and a stator 1 having armature coils 1a, 1b, 1c connected in three phases. A rotational position detector 2 that detects the relative rotational position of the rotor 10 with respect to the armature coils 1a, 1b, and 1c, and the rotation of the rotor 10 from the rotational position detector 2 is for drive control. The microcomputer 4 that switches the voltage pattern for the armature coils 1a, 1b, and 1c in response to the position signal Sint representing the position, and the switching control of the voltage pattern in the armature coils 1a, 1b, and 1c in response to the switching signal from the microcomputer 4 A drive circuit 5 for outputting a commutation control signal to be received, and a commutation control signal from the drive circuit 5 in response to armature coils 1a, 1b, And an inverter unit 6 for switching the voltage pattern.
[0029]
The rotational position detector 2 includes a resistor circuit 21 including resistors 21a, 21b, and 21c connected in three phases in parallel with the armature coils 1a, 1b, and 1c, and a voltage V at a neutral point M of the resistor circuit 21. _MN Are integrated and amplified, and a pulsing circuit 23 for pulsing the integration signal Int from the integration amplifying circuit 22 is provided.
[0030]
Here, the integral amplifier circuit 22 has a voltage V at the neutral point M of the resistor circuit 21 at the inverting input terminal of the amplifier IC1. _MN , The ground GND is connected to the non-inverting input terminal, and the resistor R1 and the capacitor C1 are connected in parallel between the output terminal and the inverting input terminal. That is, since the neutral point M of the armature coils 1a, 1b, and 1c is connected to the non-inverting input terminal of the amplifier IC1 via the ground GND, the integral amplifier circuit 22 is connected to the neutral point M of the resistor circuit 21. Potential signal V representing the potential difference between the voltage at the neutral point N and the voltage at the neutral point N of the armature coils 1a, 1b, 1c. _MN And the potential difference signal V _MN Are integrated to output an integration signal Int.
[0031]
The pulsing circuit 23 has an amplifier IC2 and a photocoupler PC. Among these, in the amplifier IC2, the integration signal Int from the integration amplifier circuit 22 is input to the inverting input terminal, and the non-inverting input terminal of the amplifier IC2 is connected to the ground GND via the resistor R2, and pulled up by the resistors R3 and R4. Has been. Further, the light emitting portion PCa of the photocoupler PC and the resistor R3 are sequentially connected in series between the output terminal and the non-inverting input terminal of the amplifier IC2. The resistor R4 pulls up the connection point between the light emitting unit PCa and the resistor R3. The photocoupler PC is for supplying the position signal Sint to the microcomputer 4 while ensuring the electrical insulation between the high power section and the weak power section. The photocoupler PC includes a light receiving section PCb and a resistor R5 of the photocoupler PC. Are connected in series between predetermined voltages, and a signal at this connection point is supplied to the microcomputer 4. The amplifier IC2 and the resistors R2 to R4 constitute a zero cross comparator.
[0032]
The microcomputer 4 is a general one having a CPU, a ROM, a RAM, and the like, and all the operations or control operations thereof are executed by software stored in advance in the ROM or the like. As a functional element of the microcomputer 4, the setting is switched between a synchronous operation mode as an initial operation and a position detection operation mode (steady operation mode) as a normal operation according to the state of the position signal Sint given from the rotational position detector 2. Mode switching means 31 to perform, synchronous operation instruction means 32 for giving an instruction of synchronous operation when the mode switching means 31 is set to the synchronous operation mode, and position when the position detection operation mode is set by the mode switching means 31 The pulse inversion confirmation means 33 for confirming the normal high / low inversion state of the pulse of the signal Sint, and only when the normal high / low inversion state can be confirmed by the pulse inversion confirmation means 33, the high / low in each pulse unit. Provided from a T measurement unit 34 for measuring a pulse width T in a low state (see FIG. 10) and an external input means 35 such as an operation panel. The target pulse width Tx (see FIG. 10) received in the microcomputer 4 and the difference between the pulse width T detected by the T measuring section 34 and the target pulse width Tx received by the target Tx input section 36. Based on the desired rotation speed and the inverter voltage V, the speed calculation section 37 that calculates the desired rotation speed according to the calculation, the inverter voltage V determination section 38 that determines the desired inverter voltage V according to the calculation result in the speed calculation section 37, and the like. A PWM modulation unit 39 that modulates and generates an appropriate PWM pulse wave and an inverter waveform signal output unit 40 that outputs an appropriate switching signal to the drive circuit 5 based on the PWM pulse wave are provided.
[0033]
The inverter unit 6 has the same configuration as the inverter unit 60 shown in FIG.
[0034]
In the above configuration, when the brushless DC motor is driven according to position detection, the induced voltages E of the U-phase, V-phase, and W-phase of the armature coils 1a, 1b, and 1c. _U , E _V , E _W As shown in FIGS. 3A to 3C, a trapezoidal waveform having a different phase every 120 degrees is obtained. The amplifier IC1 of the rotational position detector 2 shown in FIG. 2 includes the voltage at the neutral point M of the resistance circuit 21 input to the inverting input terminal and the armature coil 1a input to the non-inverting input terminal of the amplifier IC1. , 1b, 1c neutral point N voltage V _N Potential difference signal V representing the potential difference between _MN (FIG. 3D) is detected and the potential difference signal is integrated to output an integration signal Int (FIG. 3E). This integration signal Int has a substantially sine waveform with a frequency three times the rotational frequency. The pulsing circuit 23 amplifies the integration signal Int input to the inverting input terminal of the amplifier IC2 to a predetermined amplitude, photoelectrically converts the amplified integration signal Int by the photocoupler PC, and shapes the position. The signal Sint (FIG. 3F) is output.
[0035]
Next, the position signal Sint from the rotational position detector 2 is input to the mode switching means 31 from the interrupt terminal 30 of the microcomputer 4. Here, at the start of the brushless DC motor drive control device, the rotational speed of the rotor 10 gradually increases from the stopped state as shown in FIG. 4, so that the pulse width T of the position signal Sint given to the microcomputer 4 is in a stable state. It changes so as to become gradually shorter (that is, faster) until S1 is reached. For this reason, the mode switching means 31 in the microcomputer 4 sets the synchronous operation mode for a while after the activation of the brushless DC motor drive control device. That is, in step S11 in FIG. 5, first, a variable “Portbuf” indicating whether each pulse of the position signal Sint is in a high state or a low state is initialized, and then the position signal Sint is input to the interrupt terminal 30. Each time the pulse width T is detected (step S12), the pulse width T at this time is stored in the stack (step S13). At this time, the synchronous operation instructing means 32 set to the synchronous operation mode by the mode switching means 31 first gives a signal to the effect of the synchronous operation to the speed calculation section 37, and based on the signal at this time, the inverter voltage V determination section The desired inverter voltage V is determined according to 38 to obtain the desired rotation speed and inverter voltage V. Thereafter, PWM modulation is performed by the PWM modulator 39 so as to have an integral sine wave shape, and the obtained PWM pulse switching signal is output to the drive circuit 55 through the inverter waveform signal output unit 40. Based on the switching signal obtained by such an operation, the inverter unit 6 continues the synchronous operation until the rotational speed of the rotor 10 of the brushless DC motor 11 is stabilized at a predetermined level. In addition, since the inverter drive in this synchronous operation mode should just drive-control according to a general V / F constant control system, the detailed operation | movement description is abbreviate | omitted.
[0036]
Even during the synchronous operation, the mode switching means 31 of the microcomputer 4 continues to detect the pulse width T of the position signal Sint that is repeatedly input in the high / low state. When the pulse widths T of the position signals Sint continuously input a plurality of times (for example, four times) are all the same (step S14), the rotational speed of the rotor 10 has reached a stable state S1 (FIG. 4). It moves to the operation which completes synchronous operation. A variable “Port Sint” indicating whether the pulse of the position signal Sint at this time is in a high state or a low state is substituted into the aforementioned variable “Portbuf” (step S15).
[0037]
Specifically, the completion of the synchronous operation is realized by the mode switching means 31 switching from the synchronous operation mode to the position detection operation mode. At this time, the synchronous operation instruction means 32 stops functioning. As described in step S15 described above, the variable “Portbuf” is substituted with the high / low state of the pulse of the last position signal Sint in the synchronous operation mode as the initial value during the position detection operation.
[0038]
Next, the operation in the position detection operation mode after completion of the synchronous operation will be described. As shown in FIG. 6, the pulse inversion confirmation means 33 of the microcomputer 4 firstly detects the position immediately after detecting the pulse transition (trailing edge and leading edge) of the position signal Sint interrupted and inputted through the interrupt terminal 30 in step S21. It is detected whether the pulse of the signal Sint is in a high state or a low state, and this is substituted for the variable “port Sint”. Then, it is compared to determine whether or not the variable “Port Sint” matches the previously defined variable “Portbuf” (step S22).
[0039]
Here, when performing predetermined processing using the microcomputer 4, various arithmetic operations and signal input / output operations are performed while being regulated by a clock signal having a predetermined cycle. Therefore, when a predetermined interrupt process is performed in response to an interrupt input signal to the microcomputer 4, the interrupt process is executed in synchronization with the clock signal. Due to processing, register saving, and the like, the predetermined interrupt processing is completed after a certain “delay time” has elapsed from the time of signal input. Therefore, after the process of step S21 described above is performed, the process of step S22 is performed after a certain “delay time” has elapsed. That is, as shown in FIG. 7, even if the pulse transitions le, ted, and te are sequentially detected in the position signal Sint (step S21), the pulse signal of the position signal Sint at α immediately after each of the pulse transitions le, ted, and te A delay time ΔT occurs until the low state is detected (step S22). Here, when noise is superimposed on the position signal Sint, this noise appears as a pulse wave with a very short width starting from the pulse transition ted. Therefore, if the pulse width of the noise is shorter than the delay time ΔT, even if the noise is detected as the pulse transition ted in step S21, at the time when the pulse high / low state is detected in the next step S22, The position signal Sint has returned from the noise state to the steady state. That is, at the time point Tn2 in FIG. 1, the leading edge le1 is detected (step S21), and it is confirmed that the pulse input at that time is in a high state like α2 (step S22), and then the next time point When a trailing edge ted appears when noise with an extremely short pulse width is mixed in Tnd1 (step S21), αd1 becomes high when a high / low state of the pulse is detected immediately thereafter (step S22). Will be. Similarly, after detecting the trailing edge te3 at time Tn5 in FIG. 1 (step S21) and confirming that the pulse input at that time is in the low state as α5 (step S22). Next, when the leading edge led appears at time Tnd2 due to noise with a very short pulse width (step S21), αd2 is in the high state when the pulse high / low state is detected immediately after step S22. Will be.
[0040]
Thus, in step S22, if α2 (that is, the previous value “Portbuf”) and αd1 (that is, the current value “port Sint”) match, the pulse transition input this time is due to noise. You will be able to judge. Therefore, when it is determined that the two coincide with each other, it is not preferable to perform inverter control based on such noise, so the speed calculation unit 37, the inverter voltage V determination unit 38, the PWM modulation unit 39, and the inverter waveform signal are already present. While simply continuing the steady operation of the inverter defined through the output unit 40, the interruption process in step S21 is again waited. It is known that the delay time ΔT from step S21 to step S22 is usually several μs. For this reason, all noises having a pulse width of less than several μs can be canceled.
[0041]
Further, when a delay of several μs does not occur using a high-performance microcomputer, it is possible to control how many μs the time of several μs is set by creating a delay using a NOP instruction or the like in software.
[0042]
On the other hand, if it is determined in step S22 that the previous value “Portbuf” and the current value “port Sint” do not match, the pulse input this time is not a noise but a pulse of the normal position signal Sint. There will be.
[0043]
In this case, in step S23, “Port Sint”, which is the current value, is assigned to “Portbuf” in order to be used as the previous value next time.
[0044]
Next, in step S24, the pulse width T (FIG. 10) of the position signal Sint input this time is detected by the T measurement unit. On the other hand, the target pulse width Tx (FIG. 10) given from the external input means 35 such as an operation panel is received in the microcomputer 4 through the target Tx input unit 36. Then, the pulse width T detected by the T measurement unit 34 is compared with the target pulse width Tx received by the target Tx input unit 36 (step S25), and the speed calculation unit 37 determines a desired rotation speed according to the comparison result. Calculate. Further, a desired inverter voltage V is determined by the inverter voltage V determination unit 38 according to the calculation result in the speed calculation unit 37 (steps S26 and S27). At this time, in the calculation of the rotational speed and the determination of the inverter voltage V, a predetermined phase correction is also performed as shown in FIG. Then, PWM modulation is performed by the PWM modulator 39 so as to have an integral sine wave shape, and the obtained PWM pulse-like switching signal is output to the drive circuit 5 through the inverter waveform signal output unit 40 (step S28).
[0045]
The drive circuit 5 receives the switching signal from the microcomputer 4 and outputs a commutation control signal to the bases of the transistors 6 a to 6 f of the inverter unit 6. And each transistor 6a-6f of the inverter part 6 turns on / off sequentially like FIG.3 (H)-(M), and switches the voltage pattern with respect to armature coil 1a, 1b, 1c. The voltage pattern switching process is performed until time Tm1 when it is determined that the pulse width T detected by the microcomputer 4 is equal to the target pulse width Tx as shown in FIG. 10, and thereafter, the target pulse width Tx is changed to the pulse width Tx. As a result, the steady driving of the brushless DC motor by the inverter unit 6 is continued.
[0046]
In parallel with the above operation, the processing in the proposed example shown in FIG. 12B, that is, the pulse width T of the previous pulse in the position signal Sint. _n-1 "(1/2) x T _n-1 To “(3/4) × T _n-1 Until time Tm3, no signal change is accepted, and noise with a long pulse width is canceled for this portion. However, at this time, “(1/2) × T _n-1 And “(3/4) × T _n-1 The starting point of the period such as “” is the input of the pulse transition that is determined in step S22 in FIG. 6 that “port Sint” does not match “Portbuf” of the previous pulse and is a pulse transition of the normal position signal Sint. It should be the time. As a result, the influence of noise can be eliminated even in the processing as in the proposed example.
[0047]
In this way, in addition to the noise cancellation processing in the proposed example, the delay between the detection of each pulse transition at the input of each pulse of the position signal Sint and the detection of the high / low state of the pulse immediately after that is detected. Since the occurrence of the time ΔT can be used to cancel all noises having a pulse width less than the delay time ΔT, it is possible to prevent malfunctions of the microcomputer 4, the drive circuit 5 and the inverter unit 6, and inverter stoppage. Can be prevented.
[0048]
In the above embodiment, the time until the voltage pattern is switched from the position signal Sint is adjusted based on the integral signal Int. However, instead of the integral signal Int, a resistance circuit in the rotational position detector 2 is used. It is also possible to adopt the potential difference signal based on the neutral point of 21 as it is.
[0049]
【The invention's effect】
Claim 1 and claim 3 According to the invention described in (1), the level of the position signal is detected at a second time point after a predetermined delay time has elapsed from the second time point at which the transition appearing in the position signal is detected, and this is updated at the first time point Repeated every time, if the level is not reversed before and after the update, the latest detected transition is judged to be noise and ignored, while if reversed, the latest detected transition is Since the leading edge of the pulse of the normal position signal is determined and the voltage pattern is controlled based on the pulse width of the pulse, all noise having a pulse width shorter than the predetermined delay time can be canceled. Therefore, malfunction of the brushless DC motor can be prevented.
[0050]
And During synchronous operation at the time of starting the brushless DC motor drive control device, drive control is performed according to a predetermined general method or the like, and only during steady operation after completion of synchronous operation. above When performing an operation that ignores such noise, the level of the last pulse at the time of synchronous operation for the position signal is defined as the initial value of the level of the first pulse at the start of steady operation. Transition to the noise ignoring operation in steady operation can be performed efficiently.
[0051]
Claim 2 According to the invention described in claim 1, Invention described in In parallel with the above operation, for some period in each pulse of the position signal, since recognition of any pulse fluctuation is ignored, not only noise with a pulse width shorter than the predetermined delay time described above, Any noise with a longer pulse width can be canceled. Therefore, the malfunction of the brushless DC motor can be prevented more reliably. In this case, claim 1 Invention described in Can be used to discriminate the period during which the recognition of any pulse fluctuation is ignored, based on the point when it is determined that the transition of the normal position signal is a result of ignoring the noise with a short pulse width. Can be disciplined.
[0052]
From the above, it is possible to provide a brushless DC motor drive control method and apparatus that are hardly affected by noise.
[Brief description of the drawings]
FIG. 1 is a signal waveform diagram showing a state in which noise is superimposed on a position signal given to a microcomputer.
FIG. 2 is a block diagram showing a brushless DC motor drive control apparatus according to one embodiment of the present invention.
FIG. 3 is a diagram showing signal waveforms at various parts of the brushless DC motor drive control device;
FIG. 4 is a diagram showing changes in the number of rotations of a rotor in a synchronous operation at the time of startup of a brushless DC motor drive control device and a subsequent position detection operation.
FIG. 5 is a flowchart showing a synchronous operation in one embodiment of the present invention.
FIG. 6 is a flowchart showing a position detection operation in one embodiment of the present invention.
FIG. 7 is a diagram illustrating a delay time that occurs from when a position signal is supplied to the microcomputer until a high / low state of each pulse of the position signal is detected.
FIG. 8 is a block diagram showing a conventional brushless DC motor drive control device.
FIG. 9 is a flowchart showing an operation of inverter control in the microcomputer.
FIG. 10 is a waveform diagram showing a position signal given to the microcomputer.
FIG. 11 is a diagram showing the relationship between the operating frequency and torque of a brushless DC motor.
FIG. 12 is an enlarged waveform diagram showing a position signal given to the microcomputer.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Stator, 1a, 1b, 1c Armature coil, 2 Rotation position detector, 3 Level detector, 4 Microcomputer, 5 Drive circuit, 6 Inverter part, 6a-6f transistor, 7 Current sensor, 10 Rotor, 11 Brushless DC motor, 21 resistance circuit, 21a, 21b, 21c resistance, 22 integral amplification circuit, 23 pulsing circuit, 31 period calculation unit, 32 calculation unit, 33 inverter mode selection unit, 34 speed calculation unit, 35 speed control unit, 41 Level determination unit, 42 PWM unit, T1 phase correction timer, T2 period measurement timer, 45 current change determination unit, 46 stop instruction unit, AN0, AN1, AN2 analog input terminal, Iu, Iv, Iw current, Sint position signal

Claims (3)

A brushless DC motor drive control method for providing a voltage pattern based on a position signal (Sint) whose level changes according to the relative rotational position of a rotor (10) and a stator (1) of a brushless DC motor. ,
Only in steady operation after the synchronous operation at the start of the brushless DC motor drive control device is completed,
Second time point when a predetermined delay time (ΔT) has elapsed from the first time point when the transition (te1, le1, ted, te2, le2, te3, led, le3,...) Appearing in the position signal (Sint) is detected. And repeating the step of detecting the level while updating the first time point,
If the level is the same before and after each update at the first time point, the pulse having the latest detected transition (ted, led) as the leading edge is ignored, and if it is different, the latest detected The voltage pattern is controlled based on the pulse width (T) of the pulse having the transition (te1, le1, te2, le2, te3, le3,...) As a leading edge ,
The brushless DC motor characterized in that the level of the last position signal (Sint) during the synchronous operation is defined as an initial value that is the level before the first time point after the start of the steady operation. Drive control method. The brushless DC motor drive control method according to claim 1 ,
The detection of the pulse width ignores the transition until a period (0 <x <y <1) from x times to y times the pulse width (T _n-1 ) detected immediately before the pulse width is detected. And a brushless DC motor drive control method. In a brushless DC motor drive control device that provides a voltage pattern based on a position signal (Sint) whose level changes according to the relative rotational position of the rotor (10) and the stator (1) of the brushless DC motor.
Second time point when a predetermined delay time (ΔT) has elapsed from the first time point when the transition (te1, le1, ted, te2, le2, te3, led, le3,...) Appearing in the position signal (Sint) is detected. The step of detecting the level is repeated while updating the first time point, and pulse inversion confirmation means for confirming whether or not the level is reversed before and after each update of the first time point ( 33)
The pulse width of the pulse having the latest detected transition (te1, le1, te2, le2, te3, le3,...) As the leading edge when it can be confirmed by the pulse inversion confirmation means (33). On the other hand, when the speed calculation is performed based on (T) and it is confirmed by the pulse inversion confirmation means (33) that the inversion is not performed, a pulse having the latest detected transition (ted, led) as a leading edge is detected. A speed calculation unit (37) for performing speed calculation ignoring,
A signal output unit (40) for outputting a predetermined control signal for controlling the voltage pattern based on a speed calculation result in the speed calculation unit (37) ;
Mode switching means (31) for switching between a synchronous operation mode for synchronous operation when the brushless DC motor drive control device is activated and a steady operation mode for steady operation after the completion of the synchronous operation;
Synchronous operation instruction means (32) for giving an instruction for synchronous operation to the speed calculation section (37) when the mode switching means (31) is switched to the synchronous operation mode ,
The pulse inversion confirmation means (33) is operated only when the mode switching means (31) is switched to the steady operation mode,
The synchronous operation instructing means (32) uses the level of the last position signal (Sint) during the synchronous operation as an initial value that is the level before the first time point after the start of the steady operation. brushless DC motor drive controller characterized in that it is adapted to define.

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