JP4079385B2 - Brushless DC motor drive device - Google Patents

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となる。
【００１２】
ここで、ｔ₁ は非常に短い時間で、Ｅｑ₁ の式中のωとＥｑの式中のωとは等しくみなせるので、

となる。
【００１３】
点Ｐ₁ ，Ｐ₂ 間、点Ｐ₂ ，Ｐ₃ 間、点Ｐ₃ ，Ｐ₄ 間も十分に短い時間なので、ωはこの間一定であるとみなすことができ、したがって各点Ｐ₂ ，Ｐ₃ ，Ｐ₄ で印加すべき電圧Ｅｑ，Ｅｄは同様に表わすことができる。
つまり、
Ｅｑ＝Ｅｑ₁ ＋〔Ｒ・｛ｄ（Ｉｑ）／ｄｔ｝＋Ｐ・ω・Ｌｄ・｛ｄ（Ｉｄ）／ｄｔ｝・ｔ
Ｅｄ＝Ｅｄ₁ ＋〔Ｒ・｛ｄ（Ｉｄ）／ｄｔ｝−Ｐ・ω・Ｌｑ・｛ｄ（Ｉｑ）／ｄｔ｝・ｔ
となる。
【００１４】
この式からわかるように、ＥｑについてはＥｑ₁ を初期値として一定の増加率Ｐ・ω・Ｌｄ・｛ｄ（Ｉｄ）／ｄｔ｝＋Ｒ・｛ｄ（Ｉｑ）／ｄｔ｝で負方向に増加させ、ＥｄについてはＥｄ₁を初期値として一定の増加率−Ｐ・ω・Ｌｑ・｛ｄ（Ｉｑ）／ｄｔ｝＋Ｒ・｛ｄ（Ｉｄ）／ｄｔ｝（ここで、Ｒ・｛ｄ（Ｉｄ）／ｄｔ｝は値が小さいので負となる）で負方向に増加させればよいことになる。
【００１５】
これを図示すると、図３のようになる。
さらに、点Ｐ₄ 以降はモータ電流が目標位置に到達しているので、電流をそこに固定するため、Ｅｑ，Ｅｄを以下のように変えることになる。
点Ｐ₄ における印加電圧Ｅｑ，ＥｄをそれぞれＥｑ₄ ，Ｅｄ₄ とすると、Ｅｑ，Ｅｄは、点Ｐ₄ までの電流の増加率をｄ（Ｉｑ）／ｄｔ，ｄ（Ｉｄ）／ｄｔとして、

となる。ここで、Ｉｑ’，Ｉｄ ’は目標地点Ｐ₄ に達したときの電流値である。
【００１６】
しかしながら、各点ごとにＥｑ，Ｅｄを変えていくこと、具体的に言うと、各点ごとにモータへの印加電圧実効値と印加電圧周波数を変えていくことは高速な演算装置ならば実現できるが、安価な低速の演算装置では不可能である。
そこで、本発明は以下の方法により、安価な低速の演算装置でも前記のＥｑ，Ｅｄに近い印加電圧を作り出す。
【００１７】
まず、起動開始時点における回転子速度ωと、回転子位相（誘起電圧位相）θは既知であるとする。
ここで、起動目標とするＩｑ’、Ｉｄ’および起動時間ｔ₀ を設定すれば、
ｄ（Ｉｑ）／ｄｔ＝Ｉｑ’／ｔ₀ ，ｄ（Ｉｄ）／ｄｔ＝Ｉｄ’／ｔ₀
が決定される。
【００１８】
ここから、起動開始時におけるモータへの印加電圧Ｅｑ₁ ，Ｅｄ₁が（１），（２）式より次のように算出される。
Ｅｑ₁ ＝Ｅｏ・ω＋Ｌｑ・（Ｉｑ’／ｔ₀ ）
Ｅｄ₁ ＝Ｌｄ・（Ｉｄ’／ｔ₀ ）
さらに、目標（点Ｐ₄ ）到達時でのモータへの印加電圧Ｅｑ’，Ｅｄ’も（１），（２）式により次のように算出される。
【００１９】
Ｅｑ’＝Ｅｑ₁ ＋Ｒ・Ｉｑ’＋Ｐ・ω・Ｌｄ・Ｉｄ’
Ｅｄ’＝Ｅｄ₁ ＋Ｒ・Ｉｄ’−Ｐ・ω・Ｌｑ・Ｉｑ’
ここまでは、低速演算装置も高速演算装置も同じである。高速演算装置の場合、
例えば、点Ｐ₀ では
モータへの印加電圧実効値ＥｒｍｓはＥｒｍｓ＝（Ｅｑ₁ ²＋Ｅｄ₁ ²）^1/2
モータのＵ相の誘起電圧位置がθならば、Ｕ相への印加電圧Ｅｕは、
Ｅｕ＝２^1/2 ・Ｅｒｍｓ・ｓｉｎ｛Ｐ・ω・ｔ＋（δ₁ ／Δｔ）・ｔ＋ δ₀＋θ｝
Ｖ相への印加電圧Ｅｖは
Ｅｖ＝２^1/2 ・Ｅｒｍｓ・ｓｉｎ｛Ｐ・ω・ｔ＋（δ₁ ／Δｔ）・ｔ＋δ₀＋θ＋２π／３｝
同様に、点Ｐ₁ では、点Ｐ₁ に到達するまでの時間をｔ₁ として
モータへの印加電圧実効値Ｅｒｍｓ＝（Ｅｑ₂ ²＋Ｅｄ₂ ²）^1/2
Ｕ相への印加電圧Ｅｕは
Ｅｕ＝２^1/2 ・Ｅｒｍｓ・ｓｉｎ〔Ｐ・ω・ｔ＋（δ₂ ／Δｔ）・（ｔ −ｔ₁ ）＋δ₁ ＋δ₀ ＋θ〕
Ｖ相への印加電圧Ｅｖは
Ｅｖ＝２^1/2 ・Ｅｒｍｓ・ｓｉｎ〔Ｐ・ω・ｔ＋（δ₂ ／Δｔ）・（ｔ−ｔ₁ ）＋δ₁ ＋δ₀ ＋θ＋２π／３〕
以上、各点ごとに同様の処理を行うことになる。
【００２０】
低速演算装置の場合、算出したＥｑ₁ ，Ｅｄ₁ ，Ｅｑ ’，Ｅｄ ’により
δ₁ ＋δ₂ ＋δ₃ ＋δ₄ ＝ｔａｎ^-1（−Ｅｄ’ ／Ｅｑ’）
−ｔａｎ^-1（−Ｅｄ₁ ／Ｅｑ₁ ）
ここで、δ₁ ＋δ₂ ＋δ₃ ＋δ₄ ＝δ −δ₀ とおく。
この（δ −δ₀ ）についてΔｆ＝（δ −δ₀ ）／（２π・ｔ₀ ）を算出し、モータの同期周波数Ｆ（＝Ｐ・ω／２π）にΔｆを加えた周波数で初期位相δ₀ 、実効値電圧Ｅｒｍｓ＝（Ｅｑ₁ ²＋Ｅｄ₁ ²）^1/2 で時間ｔ₀ だけモータへの各相へ次のような電圧Ｅｕ，Ｅｖを印加する。
【００２１】
Ｅｕ＝２^1/2 ・Ｅｒｍｓ・ｓｉｎ〔２π・（Ｆ₀ ＋Δｆ）・ｔ＋δ₀ ＋θ〕｝
Ｅｖ＝２^1/2 ・Ｅｒｍｓ・ｓｉｎ〔２π・（Ｆ＋Δｆ）・ｔ＋δ₀ ＋θ＋ ２π／３〕
したがって、目標とすべき、図４中点線で示す印加電圧に近い印加電圧を作り出すことができるので、モータ電流Ｉｑ，Ｉｄも目標とする電流Ｉｑ’，Ｉｄ’に近い位置にもっていくことができる。
【００２２】
その後（時間ｔｏの経過後）は、出力周波数をモータ同期周波数Ｆに合わせ、かつ実効値電圧を次式
Ｅｑ＝Ｅｏ・ω＋〔Ｒ・｛ｄ（Ｉｑ）／ｄｔ｝＋Ｐ・ω・Ｌｄ・｛ｄ（Ｉｄ）／ｄｔ｝〕・ｔ₀
Ｅｄ＝〔Ｒ・｛ｄ（Ｉｄ）／ｄｔ｝−Ｐ・ω・Ｌｑ・｛ｄ（Ｉｑ）／ｄｔ｝〕・ｔ₀
のＥｑ，ＥｄによるＥｒｍｓ＝（Ｅｑ² ＋Ｅｄ² ）^1/2 に設定すれば、以後そのまま同期運転に入ることができる。
【００２３】
ブラシレスＤＣモータの駆動方法は、無通電回転中のブラシレスＤＣモータの回転子速度および回転子位相（相誘起電圧位相）を検出する際に、演算装置により直列に接続された両半導体スイッチイング素子のオン・オフ比率を制御することで確定されるモータへの出力端子電圧値を３相とも同一となるように制御してモータへ電圧出力し、かつこのときの３相のうち少なくとも２相分の前記電流検出器から得られたモータ電流値を利用する。
【００２４】
また、３相とも全て同一となる電圧出力を開始した初期における３相のうち少なくとも２相分の電流検出器により得られるモータ電流値から演算装置により算出される実効電流値に対し、モータ電流を相誘起電圧と同一方向成分であるｑ軸電流と電気角で−π／２ずれた方向成分であるｄ軸電流とに分けた場合、前記算出される実効電流値を全てｑ軸電流とし、かつ符号をマイナス値とみなすことでｑ軸電流を検出し、さらに演算装置により算出される実効電流値の変化率からｑ軸電流増加率（ｄｑ／ｄｔ）を検出する。
【００２５】
あるいは、３相とも全て同一となる電圧出力を開始した初期における３相のうち少なくとも２相分の前記電流検出器により得られるモータ電流値から前記演算装置により算出される各相電流位相値に対し、回転子位相値（相誘起電圧位相値）を電気角でπ進み、またはπ遅れとして検出する。あるいはまた、３相とも全て同一となる電圧出力を、ｑ軸電流とｄ軸電流とに分けられたモータ電流の振動が収束するまで継続し、この収束した際の３相のうち少なくとも２相分の電流検出器から得られたモータ電流値から演算装置により算出される各相電流位相値に対し、この各相電流位相値の変化率から回転子速度を検出する。
【００２６】
あるいは、３相とも全て同一となる電圧出力を前記ｑ軸電流とｄ軸電流とに分けられたモータ電流の振動が収束するまで継続し、この収束した際の３相のうち少なくとも２相分の前記電流検出器から得られたモータ電流値から前記演算装置により算出されるモータ電流実効値に対し、これを全てｄ軸電流とし、かつ符号をマイナス値とみなすことでｄ軸電流を検出し、さらに演算装置によりブラシレスＤＣモータの各特性値を使用して回転子速度を検出する。
【００２７】
あるいはまた、３相とも全て同一となる電圧出力を、ｑ軸電流とｄ軸電流とに分けられたモータ電流の振動が収束するまで継続し、この収束した際の３相のうち少なくとも２相分の電流検出器から得られたモータ電流値から演算装置により算出される各相電流位相値に対し、回転子位相値（相誘起電圧位相値）を電気角でπ／２遅れまたは３π／２進みとして検出する。
【００２８】
直列に接続された両半導体スイッチング素子のオン・オフ比率を制御することで確定されるモータへの出力端子電圧値を３相とも同一となるように制御してモータへ電圧出力することで、ブラシレスＤＣモータへの線間出力電圧値はゼロとなり、同様に相出力電圧値もゼロ（以下、これをゼロ電圧出力とする）にできる。これによりモータ電流とモータへの出力電圧とを前記のｑ軸とｄ軸とに分けて設定（図５参照）される（１），（２）式において、左辺側のＥｑ、Ｅｄが共にゼロとなる。これにより（１），（２）式は次の（３），（４）式に変更される。
【００２９】
０＝Ｅｏ・ω＋Ｒ・Ｉｑ＋Ｐ・ω・Ｌｄ・Ｉｄ＋Ｌｑ・｛ｄ（Ｉｑ）／ｄｔ｝・・・・（３）
０＝Ｒ・Ｉｄ−Ｐ・ω・Ｌｑ・Ｉｑ＋Ｌｄ・｛ｄ（Ｉｄ）／ｄｔ｝・・・・（４）
ここで、無通電回転中のブラシレスＤＣモータに対しゼロ電圧出力した場合のモータ電流の動きは上記（３），（４）式においてＩｑとＩｄの初期値を共にゼロとした場合の電流の動きとなる。
【００３０】
このＩｑとＩｄの時間経過による変化の様子を示したものが図１１および図１２である。
図１１はゼロ電圧出力開始当初の両軸電流波形の動きを示したものであり、必ずＩｑが先にマイナス値から立ち上りＩｄはやや遅れてから立ち上がる。その後両軸電流は共に振動しながら徐々に収束してゆき、Ｉｑはゼロに、Ｉｄは回転子速度に対応したマイナス値に収束していく様子を図１２に示している。
【００３１】
ここで、前記記載の方法により、電流検出器を例えばＶ相電流（Ｉｖ）とＷ相電流（Ｉｗ）を検出するように配置したとすれば、図１１に示したゼロ電圧出力開始当初の両軸電流の動きから演算装置により算出したモータ電流実効値Ｉｒｍｓにおいて、
Ｉｒｍｓ＝｛Ｉｗ・Ｉｗ／２＋（Ｉｗ＋２・Ｉｖ）・（Ｉｗ＋２・Ｉｖ）／
６｝^1/2
＝（Ｉｑ・Ｉｑ＋Ｉｄ・Ｉｄ）^1/2 ≒−Ｉｑ （∵Ｉｄ≒０）
とみなすことができ、さらには
ｄ（Ｉｑ）／ｄｔ≒ｄ（−Ｉｒｍｓ）／ｄｔ
とみなすこともできる。
【００３２】
上記の算出値（Ｉｑ，ｄ（Ｉｑ）／ｄｔ，Ｉｄ）をブラシレスＤＣモータの各特性値（Ｅｏ，Ｐ，Ｒ，Ｌｄ，Ｌｑ）を使用して式（３）に代入すればブラシレスＤＣモータの回転子速度（ω）が検出できる。さらに、前記記載の方法により、３相とも全て同一となる電圧出力を開始した初期における３相のうち少なくとも２相分の電流検出器により得られるモータ電流値から演算装置により算出される各相電流位相値に対し、このモータ電流は図１１に示すようにｑ軸のマイナス電流とみなせることから、回転子位相値（相誘起電圧位相値）は各相のモータ電流位相値に対し電気角でπ進んだまたはπ遅れた位置にくるので回転子位相値（相誘起電圧位相値）も検出できる。
【００３３】
以上に記載の方法により脱調回転中のモータに直結した回転子位置検出手段をもたないブラシレスＤＣモータにおいて回転を停止することなくそのまま同期運転に引き込むために必要な情報であるブラシレスＤＣモータの回転子速度および回転子位相値（相誘起電圧位相値）を検出することができる。あるいは、前記記載の手段により３相とも全て同一となる電圧出力を、ｑ軸電流とｄ軸電流とに分けられたモータ電流の振動がｑ軸電流はゼロに、ｄ軸電流は回転子速度に対応したマイナス値に収束するまで継続し、この収束した際の３相のうち少なくとも２相分の電流検出器から得られたモータ電流値から演算装置により算出される各相電流位相値に対し、この各相電流位相値の変化率から回転子速度は検出できる。あるいはまた、前記記載の手段により３相のうち少なくとも２相分の電流検出器から得られたモータ電流値から演算装置により算出されるモータ電流実効値に対し、図１２に示すようにこれを全てｄ軸電流のマイナス電流とみなせるので、
ｄ（Ｉｑ）／ｄｔ≒０
Ｉｑ≒０
とみなせること、およびブラシレスＤＣモータの各特性値（Ｅｏ，Ｐ，Ｒ，Ｌｄ，Ｌｑ）を使用して式（３）に代入すればブラシレスＤＣモータの回転子速度（ω）が検出できる。
【００３４】
さらに、前記記載の方法により３相のうち少なくとも２相分の電流検出器から得られたモータ電流値から演算装置により算出される各相電流位相値に対し、このモータ電流は図１２に示すようにｄ軸のマイナス電流とみなせることから、回転子位相値（相誘起電圧位相値）は各相のモータ電流位相値に対し電気角でπ／２遅れたまたは３π／２進んだ位置にくるので回転子位相値（相誘起電圧位相値）も検出できる。
【００３５】
以上に記載の方法により、または以上に記載の手段によっても脱調回転中のモータに直結した回転子位置検出手段を持たないブラシレスＤＣモータにおいて回転を停止することなくそのまま同期運転に引き込むために必要な情報であるブラシレスＤＣモータの回転子速度および回転子位相値（相誘起電圧位相値）を検出することができる。
【００３６】
【発明の実施の形態】
次に、本発明の実施の形態について図面を参照して説明する。図１は本発明の第１の実施形態のブラシレスＤＣモータの駆動装置の構成図である。本実施形態のブラシレスＤＣモータの駆動装置は、３相Ｙ結線に接続されたそれぞれＵ相、Ｖ相、Ｗ相電機子コイル７，８，９からなる固定子と複数極の磁石を有する回転子１０からなり、モータ軸に直結された回転子位置検出手段を持たないブラシレスＤＣモータ１４を駆動するもので、直流電源１と、トランジスタＳ₁ 〜Ｓ₆ からなる半導体スイッチング素子群２と、演算装置３Ａと、演算装置３Ａから半導体スイッチング素子群２へのオン・オフ命令をドライブ信号として半導体スイッチング素子群２へ伝送するドライブ回路部４と、モータ電流を検出する電流検出器５，６と、Ｕ，Ｖ，Ｗ各相の出力端子１１，１２，１３で構成されている。ここで、回転子速度と回転子位相は演算装置３Ａと電流検出器５、６によって前もって検出されている。
【００３７】
非同期回転中にあるブラシレスＤＣモータ１４を演算装置３Ａとドライブ回路部４とにより半導体スイッチング素子群２を全てオフにして無通電状態とした上で、設定したモータ電流のｄ（Ｉｑ）／ｄｔ，ｄ（Ｉｄ）／ｄｔとモータの各特性値Ｅｏ，Ｐ，Ｒ，Ｌｑ，Ｌｄと検出されたブラシレスＤＣモータ１４の回転子速度および回転子位相とから演算装置３ＡによりブラシレスＤＣモータ１４への初期両軸出力電圧Ｅｑ₁ ，Ｅｄ₁ と初期出力周波数（同期周波数（Ｆ）＋△ｆ）を〔課題を解決するための手段〕の項に記載の方法により算出して起動時間ｔ₀ 区間中のみブラシレスＤＣモータ１４へ出力する。起動時間ｔ₀ 経過後は、演算装置３Ａにより出力電圧実効値を〔課題を解決するための手段〕の項記載の方法により変更し、かつ出力周波数も同期周波数に変更することでブラシレスＤＣモータ１４をそのまま同期運転に引き込む。
【００３８】
図６は本発明の第２の実施形態のブラシレスＤＣモータの駆動装置の構成図、図７〜図１０は図６中の各相の出力端子１１，１２，１３の電圧値を同一とするための半導体スイッチング素子群２へのオン／オフドライブ信号の状態を示す図である。演算装置３Ｂのみが高速演算装置、低速演算装置いずれの場合もあり得るという点で、図１中のドライブ装置３Ａと異なっている。
【００３９】
演算装置３Ｂは、無通電回転中のブラシレスＤＣモータ１４の回転子速度および回転子位相（相誘起電圧位相）を検出する際に、電流検出器５，６から得られたモータ電流値を利用して、ブラシレスＤＣモータ１４への出力端子電圧値が３相とも同一となるように、図７〜図１０に示すように、直列に接続されたトランジスタＳ₁ とＳ₄ 、Ｓ₂ とＳ₅ 、Ｓ₃ とＳ₆ のオン／オフのデューティ比を算出し、そのデューティ比に基づいた、半導体スイッチ素子群２のオン／オフ命令をドライブ信号としてドライブ回路部４に出力する。
【００４０】
また、図９、図１０においては各相の上下両トランジスタＳ₁ と Ｓ₄ 、Ｓ₂ とＳ₅ 、Ｓ₃ とＳ₆ の同時オンを防止するために各キャリア周期において設定されている上下両トランジスタＳ₁ とＳ₄ 、Ｓ₂ とＳ₅ 、Ｓ₃ とＳ₆ の同時オフ時間（以下、これをデッドタイムとする）の影響（ドライブ信号のデューティ比から決定される出力電圧よりも常に（デッドタイム）×Ｖ_DC／Ｔ（Ｖ_DCは直流電源１の電圧、Ｔはキャリア周期）だけ実際の電圧がずれること）を修正するために、電流検出器５，６により検出した各相電流の正負極性値をもとに演算装置３Ｂにより上下両トランジスタＳ₁ とＳ₄ 、Ｓ₂ とＳ₅ 、Ｓ₃ とＳ₆ のオン／オフ比率を修正し、各相の出力端子電圧値をより正確に同一にすることもできる。すなわち、モータ電流の極性により出力電圧がプラス側、マイナス側のどちらにずれるのかを判断できるので、電流検出器５，６によりその相のモータ電流が正極性と判別されれば、マイナス側にデッドタイム分だけ出力電圧がずれるので、逆に上段側トランジスタのオン幅をデッドタイム分増加させてそのずれ分をキャンセルし、モータ電流が負極性と判別されれば、逆に上段側トランジスタのオン幅をデッドタイム分減少させる。
【００４１】
以上によりブラシレスＤＣモータ１４へのゼロ電圧出力を行い、このゼロ電圧出力開始当初の電流検出器５，６により検出した、例えばＶ相とＷ相の同一時間におけるそれぞれの瞬時検出電流値をもとに、〔課題を解決するための手段〕の項において説明した方法によりブラシレスＤＣモータ１４の回転子速度および回転子位相値（相誘起電圧位相値）を検出する。検出後は、検出した回転子速度と回転子位相値（相誘起電圧位相値）に基づき演算装置３Ｂにより適切な出力電圧を算出し、ブラシレスＤＣモータ１４に電圧出力して同期運転に引き込めばよい。
【００４２】
次に、本発明の第３の実施形態を説明する。構成は、第２の実施形態として示した図６および図７〜図１０と同じである。ブラシレスＤＣモータ１４へのゼロ電圧出力をｑ軸電流とｄ軸電流とに分けられたモータ電流の振動がｑ軸電流はゼロに、ｄ軸電流は回転子速度に対応したマイナス値に収束するまで継続し、この収束した際のモータ電流を電流検出器５，６により検出した、例えばＶ相とＷ相の同一時間におけるそれぞれの瞬時検出電流値をもとに、〔課題を解決するための手段〕の項において説明した方法により、ブラシレスＤＣモータ１４の回転子速度および回転子位相値（相誘起電圧位相値）を検出する。また、モータ電流の収束状態の確認は、ゼロ電圧出力開始後前もって設定した時間を経過したかどうかで判断するか、またあるいは検出した実効値電流の変動量（図１２参照）で、またあるいは検出した各相電流位相値の変動量で判断できる。
【００４３】
図７〜図１０の各相の出力端子電圧値を同一とするための半導体スイッチング素子群２へのオン／オフドライブ信号の状態において、図７と図８はそれぞれ下側のあるいは上側のトランジスタに負担が集中するのでこれを避けるために半導体スイッチング素子群２へのオン／オフドライブ信号を適当な時間間隔で図７と図８とで交互に入れ替えることも考えられる。
【００４４】
次に、本発明の第４の実施形態について説明する。これは、第３の実施形態に対しブラシレスＤＣモータ１４の回転子速度を、〔課題を解決するための手段〕の項において説明した方法により検出する点が異なる。
【００４５】
【発明の効果】
以上説明したように、本発明は下記のような効果がある。
非同期回転中のモータに直結した回転子位置検出手段を持たないブラシレスＤＣモータに対し、安価な演算装置により短時間で安定したモータ電流を起動でき、ブラシレスＤＣモータの回転を停止することなくそのまま起動して同期運転に引き込むことができる。
【００４６】
脱調回転中のモータに直結した回転子位置検出手段を持たないブラシレスＤＣモータに対し、無通電状態からモータへの出力端子電圧値を３相とも同一となるように制御してモータへ電圧出力し、かつこのときの３相のうち少なくとも２相分の電流検出器から得られたモータ電流値を利用することで、ブラシレスＤＣモータの回転を停止させることなくそのまま同期運転に引き込むために必要な情報であるブラシレスＤＣモータの回転子速度および回転子位相値（相誘起電圧位相値）を検出することができるので、脱調回転中のブラシレスＤＣモータに対し回転を停止させることなくそのまま同期運転に引き込むことができる。
【図面の簡単な説明】
【図１】本発明の第１の実施形態の、ブラシレスＤＣモータの駆動装置の構成図である。
【図２】モータ電流を安定に起動させる際のｑ軸電流とｄ軸電流の動きを示す図である。
【図３】モータ電流を安定に起動させる際の出力電圧ｑ軸成分とｄ軸成分の動きを示す図である。
【図４】図１の実施形態における出力電圧ｑ軸成分とｄ軸成分の動きを示す図である。
【図５】モータ電流と各電圧とをｑ軸とｄ軸に分けたベクトル図である。
【図６】本発明の第２の実施形態の、ブラシレスＤＣモータの駆動装置の構成図である。
【図７】図６中における出力端子１１，１２，１３の電圧値を同一とするための半導体スイッチング素子群２へのオン／オフドライブ信号の状態を示す図である。
【図８】図６中における出力端子１１，１２，１３の電圧値を同一とするための半導体スイッチイング素子群２ヘのオン／オフドライブ信号の状態を示す図である。
【図９】図６中における出力端子１１，１２，１３の電圧値を同一とするための半導体スイッチング素子群２へのオン／オフドライブ信号の状態を示す図である。
【図１０】図６中における出力端子１１，１２，１３の電圧値を同一とするための半導体スイッチング素子群へのオン／オフドライブ信号の状態を示す図である。
【図１１】ゼロ電圧出力開始当初のｑ軸電流波形とｄ軸電流波形を示す図である。
【図１２】ゼロ電圧出力時のｑ軸電流波形とｄ軸電流波形の収束していく様子を示す図である。
【図１３】従来のブラシレスＤＣモータの駆動装置の構成例を示す図である。
【符号の説明】
１ 直流電源
２ 半導体スイッチング素子群
３Ａ，３Ｂ 演算装置
４ ドライブ回路部
５，６ 電流検出器
７，８，９ 電機子コイル
１０ 回転子
１１，１２，１３ 出力端子
１４ ブラシレスＤＣモータ
Ｓ₁ 〜Ｓ₆ トランジスタ[0001]
BACKGROUND OF THE INVENTION
The present invention has a DC power supply, a semiconductor switching element connected to the positive electrode side of the DC power supply, and a semiconductor switching element connected to the negative electrode side. A rotor having a multi-pole magnet and a three-phase Y-connection with a motor current detector and an arithmetic unit for at least two phases of the three phases, which are connected and the connection point is an output terminal to the motor A brushless DC motor driving device having no rotor position detecting means directly connected to the motor and having a rotor speed during asynchronous rotation of the brushless DC motor, and a stator having an armature coil connected to the motor The present invention relates to a method of driving a brushless DC motor by a brushless DC motor driving device provided with a rotor phase (phase induced voltage phase) detection means.
[0002]
[Prior art]
FIG. 13 is a configuration diagram of a conventional brushless DC motor driving apparatus described in Japanese Patent Laid-Open No. 3-207290.
This brushless DC motor drive device is composed of a rotor 10 having a plurality of magnetic poles and a stator having armature coils 7, 8, 9 connected to a three-phase Y connection, and a rotational position detecting means directly connected to the motor. The brushless DC motor 14 having no motor is driven, and includes a semiconductor switching element group 2, a position detection / rotation control device 15, a microcomputer 16, and a time detector 17.
[0003]
The time detector 17 receives a part of the rotation signal of the semiconductor switching element group 2 from the position detection rotation control device 15, measures the time from the output of a certain rotation signal to the output of the next rotation signal, and the microcomputer. The data is sent to 16. The microcomputer 16 determines the data sent from the time detector 17, determines that the step-out has occurred when the time is shorter than a predetermined time, and then controls the restart of the step-out.
[0004]
[Problems to be solved by the invention]
However, in the conventional configuration, when a brushless DC motor without a rotor position detection unit directly connected to the motor steps out, it is necessary to wait for the brushless DC motor to stop and then start up again. There has been a problem that the rotating motor cannot be directly pulled into the synchronous operation without being stopped.
[0005]
SUMMARY OF THE INVENTION An object of the present invention is to provide a brushless DC motor driving method that can be directly pulled into synchronous operation without stopping rotation for a brushless DC motor that does not have rotor position detection means directly connected to the motor during asynchronous rotation. Is to provide.
[0006]
[Means for Solving the Problems]
  The present inventionofThe brushless DC motor is driven in such a manner that a brushless DC motor that is rotating asynchronously is not energized, and a voltage having a voltage frequency higher than the motor synchronous frequency corresponding to the detected rotor speed of the brushless DC motor is applied for a short time. Only the output is returned to the synchronous frequency and the asynchronous brushless DC motor is pulled into the synchronous operation.
[0007]
  The present inventionAccording to this embodiment, when starting the motor current from the non-energized state, the motor current is d-axis current that is a direction component that is deviated by −π / 2 in electrical angle from the q-axis current that is the same direction component as the phase induced voltage. The q-axis current is driven at a constant increase rate in the positive direction, and the d-axis current is driven at a constant increase rate in the negative direction. The motor current and the motor voltage have a relationship satisfying the following voltage equations (1) and (2) set separately for the q axis and the d axis (see FIG. 5).
[0008]
Eq = Eo · ω + R · Iq + P · ω · Ld · Id + Lq · {d (Iq) / dt} (1)
Ed = R · Id−P · ω · Lq · Iq + Ld · {d (Id) / dt} (2)
Eq: q-axis component of the output voltage to the motor
Ed: d-axis component of the output voltage to the motor
Eo: Motor induced voltage constant
ω: Motor rotor speed
P: Number of rotor pole pairs
R: Armature winding resistance value of the motor
Lq: q-axis inductance of the motor
Ld: d-axis inductance of the motor
Iq: q-axis current of the motor
Id: d-axis current of the motor
In order for the permanent magnet synchronous motor to generate a large positive output torque in a synchronized state, the motor current needs to be at a position indicated by a circle in FIG.
[0009]
Therefore, in order to instantaneously pull the motor into the synchronized state, it is necessary to instantly start the motor current to the above position and stabilize it there. Since the motor current is zero at the start of startup, the position P shown in FIG.₀ It becomes.
Considering the stability of the current path from the starting position to the target position, it is increased linearly and constantly as shown in FIG. As you can see from this route
q-axis current increase rate: d (Iq) / dt = constant> 0
d-axis current increase rate: d (Id) / dt = constant <0
It becomes.
[0010]
Therefore, if the motor current is to be started in this way, the point P₀ Is obtained by substituting Id = Iq = 0 in the equations (1) and (2).
Eq₁= Eo · ω + Lq · {d (Iq) / dt} ·· Output voltage q-axis component initial value
Ed₁= Ld · {d (Id) / dt} ············ Output voltage d-axis component initial value
Is applied to the motor.
[0011]
Also, point P₁ In t₁ Then, here Iq and Id are
Iq = {d (Iq) / dt} · t₁
Id = {d (Id) / dt} · t₁
It has become.
Substituting this into the equations (1) and (2), the applied voltages Eq and Ed are

It becomes.
[0012]
Where t₁ Is a very short time, Eq₁ Since ω in Eq and Eq can be regarded as equal,

It becomes.
[0013]
Point P₁ , P₂ Between, point P₂ , P_Three Between, point P_Three , P_Four Since the time is sufficiently short, ω can be considered constant during this time, and therefore each point P₂ , P_Three , P_Four The voltages Eq and Ed to be applied can be expressed similarly.
That means
Eq = Eq₁ + [R · {d (Iq) / dt} + P · ω · Ld · {d (Id) / dt} · t
Ed = Ed₁ + [R · {d (Id) / dt} −P · ω · Lq · {d (Iq) / dt} · t
It becomes.
[0014]
As can be seen from this equation, for Eq, Eq₁ Is increased in the negative direction at a constant increase rate P · ω · Ld · {d (Id) / dt} + R · {d (Iq) / dt}, with Ed being Ed.₁Is a constant increase rate −P · ω · Lq · {d (Iq) / dt} + R · {d (Id) / dt} (where R · {d (Id) / dt} has a value) If it is small, it becomes negative).
[0015]
This is illustrated in FIG.
Furthermore, point P_Four Thereafter, since the motor current has reached the target position, Eq and Ed are changed as follows in order to fix the current there.
Point P_Four Applied voltages Eq, Ed at Eq respectively_Four , Ed_Four Then, Eq and Ed are points P_Four The increase rate of current up to d (Iq) / dt, d (Id) / dt

It becomes. Here, Iq ′ and Id ′ are target points P_Four This is the current value when the value reaches.
[0016]
However, changing Eq and Ed for each point, specifically speaking, changing the effective voltage applied to the motor and the applied voltage frequency for each point can be realized by a high-speed computing device. However, this is not possible with an inexpensive low-speed computing device.
Therefore, the present invention creates an applied voltage close to Eq and Ed even with an inexpensive low-speed arithmetic device by the following method.
[0017]
First, it is assumed that the rotor speed ω and the rotor phase (induced voltage phase) θ at the start of activation are already known.
Here, Iq ′ and Id ′ as activation targets and activation time t₀ If you set
d (Iq) / dt = Iq '/ t₀ , D (Id) / dt = Id ′ / t₀
Is determined.
[0018]
From here, the applied voltage Eq to the motor at the start of startup₁ , Ed₁Is calculated from the equations (1) and (2) as follows.
Eq₁ = Eo · ω + Lq · (Iq ′ / t₀ )
Ed₁ = Ld · (Id ′ / t₀ )
Furthermore, the target (point P_Four ) The applied voltages Eq 'and Ed' to the motor at the time of arrival are also calculated as follows using the equations (1) and (2).
[0019]
Eq '= Eq₁ + R · Iq '+ P · ω · Ld · Id'
Ed '= Ed₁ + R · Id'-P · ω · Lq · Iq '
Up to this point, the low-speed arithmetic device and the high-speed arithmetic device are the same. For high-speed computing devices,
For example, point P₀ Then
The effective voltage Erms applied to the motor is Erms = (Eq₁ ²+ Ed₁ ²)^1/2
If the induced voltage position of the U phase of the motor is θ, the applied voltage Eu to the U phase is
Eu = 2^1/2 · Erms · sin {P · ω · t + (δ₁ / Δt) · t + δ₀+ Θ}
The applied voltage Ev to the V phase is
Ev = 2^1/2 · Erms · sin {P · ω · t + (δ₁ / Δt) · t + δ₀+ Θ + 2π / 3}
Similarly, point P₁ Then point P₁ The time to reach₁ As
Effective voltage applied to motor Erms = (Eq₂ ²+ Ed₂ ²)^1/2
The applied voltage Eu to the U phase is
Eu = 2^1/2 ・ Erms ・ sin [P ・ ω ・ t + (δ₂ / Δt) · (t −t₁ ) + Δ₁ + Δ₀ + Θ]
The applied voltage Ev to the V phase is
Ev = 2^1/2 ・ Erms ・ sin [P ・ ω ・ t + (δ₂ / Δt) · (t−t₁ ) + Δ₁ + Δ₀ + Θ + 2π / 3]
As described above, the same processing is performed for each point.
[0020]
In the case of a low speed computing device, the calculated Eq₁ , Ed₁ , Eq ', Ed'
δ₁ + Δ₂ + Δ_Three + Δ_Four = Tan^-1(-Ed '/ Eq')
-Tan^-1(-Ed₁ / Eq₁ )
Where δ₁ + Δ₂ + Δ_Three + Δ_Four = Δ -δ₀ far.
This (δ −δ₀ ) Δf = (δ−δ)₀ ) / (2π · t₀ ) And the initial phase δ at a frequency obtained by adding Δf to the synchronous frequency F (= P · ω / 2π) of the motor.₀ , RMS voltage Erms = (Eq₁ ²+ Ed₁ ²)^1/2 At time t₀ Only the following voltages Eu and Ev are applied to each phase to the motor.
[0021]
Eu = 2^1/2 ・ Erms ・ sin [2π ・ (F₀ + Δf) · t + δ₀ + Θ]}
Ev = 2^1/2 Erms · sin [2π · (F + Δf) · t + δ₀ + Θ + 2π / 3]
Therefore, since an applied voltage close to the applied voltage shown by the dotted line in FIG. 4 can be created, the motor currents Iq and Id can also be brought close to the target currents Iq ′ and Id ′. .
[0022]
After that (after the time to elapses), the output frequency is adjusted to the motor synchronous frequency F, and the effective value voltage is expressed by the following equation.
Eq = Eo · ω + [R · {d (Iq) / dt} + P · ω · Ld · {d (Id) / dt}] · t₀
Ed = [R · {d (Id) / dt} −P · ω · Lq · {d (Iq) / dt}] · t₀
Of Eq, Ed of Erms = (Eq² + Ed² )^1/2 If set to, synchronous operation can be started as it is thereafter.
[0023]
  TheThe driving method of the laciless DC motor is to detect the rotor speed and the rotor phase (phase induced voltage phase) of the brushless DC motor during non-energized rotation, by using both semiconductor switching elements connected in series by the arithmetic unit. The output terminal voltage value to the motor determined by controlling the on / off ratio is controlled so that all three phases are the same, and voltage is output to the motor, and at least two phases of the three phases at this time are output. The motor current value obtained from the current detector is used.
[0024]
  AlsoThe motor current is compared with the effective current value calculated by the arithmetic unit from the motor current value obtained by the current detector for at least two phases of the initial three phases when the voltage output is the same for all three phases. When divided into a q-axis current that is a component in the same direction as the induced voltage and a d-axis current that is a direction component shifted by −π / 2 in terms of electrical angle, the calculated effective current values are all q-axis currents, and Q-axis current is detected by assuming that is a negative value, and the q-axis current increase rate (dq / dt) is detected from the change rate of the effective current value calculated by the arithmetic unit.
[0025]
  OrFor each phase current phase value calculated by the arithmetic unit from the motor current value obtained by the current detector for at least two phases of the three phases in the initial stage in which the voltage output is the same for all three phases. The rotor phase value (phase induced voltage phase value) is detected as an π advance or π delay in electrical angle.Or againThe voltage output that is the same for all three phases is continued until the vibration of the motor current divided into the q-axis current and the d-axis current converges, and the current for at least two phases of the three phases at the time of convergence For each phase current phase value calculated by the arithmetic unit from the motor current value obtained from the detector, the rotor speed is detected from the rate of change of each phase current phase value.
[0026]
  OrThe voltage output that is the same for all three phases continues until the vibration of the motor current divided into the q-axis current and the d-axis current converges, and at least two phases of the three phases at the time of convergence converge. The d-axis current is detected by regarding all the motor current effective values calculated by the arithmetic unit from the motor current values obtained from the current detector as d-axis currents and taking the sign as a negative value. An arithmetic unit detects the rotor speed using each characteristic value of the brushless DC motor.
[0027]
  Or againThe voltage output that is the same for all three phases is continued until the vibration of the motor current divided into the q-axis current and the d-axis current converges, and the current for at least two phases of the three phases at the time of convergence The rotor phase value (phase induced voltage phase value) is detected as an electrical angle of π / 2 delay or 3π / 2 advance with respect to each phase current phase value calculated by the arithmetic unit from the motor current value obtained from the detector. To do.
[0028]
By controlling the on / off ratio of both semiconductor switching elements connected in series, the output terminal voltage value to the motor determined to be the same for all three phases and outputting the voltage to the motor is brushless. The line output voltage value to the DC motor becomes zero, and similarly, the phase output voltage value can also be zero (hereinafter referred to as zero voltage output). As a result, the motor current and the output voltage to the motor are set separately for the q-axis and d-axis (see FIG. 5). In equations (1) and (2), Eq and Ed on the left side are both zero. It becomes. As a result, the expressions (1) and (2) are changed to the following expressions (3) and (4).
[0029]
0 = Eo · ω + R · Iq + P · ω · Ld · Id + Lq · {d (Iq) / dt} (3)
0 = R · Id-P · ω · Lq · Iq + Ld · {d (Id) / dt} (4)
Here, the movement of the motor current when a zero voltage is output to the brushless DC motor during non-energized rotation is the movement of the current when the initial values of Iq and Id are both zero in the above formulas (3) and (4). It becomes.
[0030]
FIGS. 11 and 12 show changes in Iq and Id over time.
FIG. 11 shows the movement of the biaxial current waveform at the beginning of the zero voltage output. Iq always rises from a negative value first, and Id rises after a slight delay. Thereafter, both shaft currents gradually converge while oscillating, and Iq is zero and Id is converged to a negative value corresponding to the rotor speed.
[0031]
  here,SaidIf the current detector is arranged to detect, for example, the V-phase current (Iv) and the W-phase current (Iw) by the described method, the movement of the biaxial current at the beginning of the zero voltage output shown in FIG. From the motor current effective value Irms calculated by the arithmetic unit from
    Irms = {Iw · Iw / 2 + (Iw + 2 · Iv) · (Iw + 2 · Iv) /
      6}^1/2
            = (Iq · Iq + Id · Id)^1/2 ≒ -Iq (∵Id ≒ 0)
Can be considered, and
    d (Iq) / dt≈d (−Irms) / dt
Can also be considered.
[0032]
  If the calculated values (Iq, d (Iq) / dt, Id) are substituted into the equation (3) using the characteristic values (Eo, P, R, Ld, Lq) of the brushless DC motor, the brushless DC motor The rotor speed (ω) can be detected. further,SaidAccording to the described method, each phase current phase value calculated by the arithmetic unit is calculated from the motor current value obtained by the current detector for at least two phases of the three phases in the initial stage when the voltage output in which all three phases are the same is started On the other hand, since this motor current can be regarded as a negative current of the q axis as shown in FIG. 11, the rotor phase value (phase induced voltage phase value) is advanced by π in electrical angle with respect to the motor current phase value of each phase or Since the position is delayed by π, the rotor phase value (phase induced voltage phase value) can also be detected.
[0033]
  more thanInThe brushless DC motor rotor, which is information necessary for pulling in the synchronous operation without stopping the rotation in the brushless DC motor without the rotor position detecting means directly connected to the motor that is out of rotation by the described method. Speed and rotor phase value (phase induced voltage phase value) can be detected. OrSaidThe voltage output that is the same for all three phases by the described means, the vibration of the motor current divided into the q-axis current and the d-axis current is zero, and the d-axis current is minus corresponding to the rotor speed. It continues until it converges to the value, and for each phase current phase value calculated by the arithmetic unit from the motor current value obtained from the current detector for at least two phases of the three phases at the time of convergence, The rotor speed can be detected from the rate of change of the current phase value. Alternatively,SaidWith respect to the effective motor current value calculated by the arithmetic unit from the motor current values obtained from the current detectors for at least two phases among the three phases by the described means, this is all converted to the d-axis current as shown in FIG. Since it can be regarded as a negative current,
          d (Iq) / dt≈0
          Iq ≒ 0
And the rotor speed (ω) of the brushless DC motor can be detected by substituting into the equation (3) using the characteristic values (Eo, P, R, Ld, Lq) of the brushless DC motor.
[0034]
  further,SaidFor each phase current phase value calculated by the arithmetic unit from the motor current values obtained from the current detectors for at least two of the three phases by the described method, the motor current is d-axis as shown in FIG. Therefore, the rotor phase value (phase induced voltage phase value) is at a position that is delayed by π / 2 or advanced by 3π / 2 in electrical angle with respect to the motor current phase value of each phase. The value (phase induced voltage phase value) can also be detected.
[0035]
  more thanInAs described ormore thanThe brushless DC motor rotor, which is information necessary for pulling in the synchronous operation as it is without stopping the rotation in the brushless DC motor which does not have the rotor position detecting means directly connected to the motor that is out of rotation by the described means. Speed and rotor phase value (phase induced voltage phase value) can be detected.
[0036]
DETAILED DESCRIPTION OF THE INVENTION
  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a first embodiment of the present invention.StateIt is a block diagram of the drive device of a brushless DC motor. The brushless DC motor driving apparatus of the present embodiment is a rotor having a stator composed of U-phase, V-phase, and W-phase armature coils 7, 8, and 9 connected to a three-phase Y connection, and a magnet having a plurality of poles. 10, which drives a brushless DC motor 14 having no rotor position detecting means directly connected to the motor shaft.₁ ~ S₆ A semiconductor switching element group 2, an arithmetic device 3A, a drive circuit unit 4 for transmitting an on / off command from the arithmetic device 3A to the semiconductor switching element group 2 as a drive signal to the semiconductor switching element group 2, and a motor current It comprises current detectors 5 and 6 to be detected, and output terminals 11, 12 and 13 for U, V and W phases. Here, the rotor speed and the rotor phase are detected in advance by the arithmetic unit 3A and the current detectors 5 and 6.
[0037]
The brushless DC motor 14 in the asynchronous rotation is turned off by turning off the semiconductor switching element group 2 by the arithmetic device 3A and the drive circuit unit 4, and then d (Iq) / dt, From the d (Id) / dt, the motor characteristic values Eo, P, R, Lq, and Ld, and the detected rotor speed and rotor phase of the brushless DC motor 14, an initial operation for the brushless DC motor 14 is performed by the arithmetic unit 3A. Biaxial output voltage Eq₁ , Ed₁ And the initial output frequency (synchronization frequency (F) + Δf) is calculated by the method described in the section of [Means for Solving the Problems], and the start time t₀ Output to the brushless DC motor 14 only during the section. Startup time t₀ After the lapse of time, the output voltage effective value is changed by the method described in the section [Means for Solving the Problems] by the arithmetic device 3A, and the output frequency is also changed to the synchronous frequency, so that the brushless DC motor 14 is synchronously operated as it is. Pull in.
[0038]
  FIG. 6 shows a second embodiment of the present invention.StateFIG. 7 to FIG. 10 are diagrams showing the configuration of a brushless DC motor driving device, and FIG. 7 to FIG. 10 show on / off drive to the semiconductor switching element group 2 for making the voltage values of the output terminals 11, 12, 13 of each phase in FIG. It is a figure which shows the state of a signal. 1 is different from the drive device 3A in FIG. 1 in that only the arithmetic device 3B can be a high-speed arithmetic device or a low-speed arithmetic device.
[0039]
The arithmetic device 3B uses the motor current value obtained from the current detectors 5 and 6 when detecting the rotor speed and the rotor phase (phase induced voltage phase) of the brushless DC motor 14 during non-energized rotation. As shown in FIGS. 7 to 10, the transistor S connected in series so that the output terminal voltage value to the brushless DC motor 14 is the same in all three phases.₁ And S_Four , S₂ And S_Five , S_Three And S₆ The on / off duty ratio of the semiconductor switch element group 2 is calculated, and an on / off command for the semiconductor switch element group 2 based on the duty ratio is output to the drive circuit unit 4 as a drive signal.
[0040]
9 and 10, the upper and lower transistors S of each phase.₁ And S_Four , S₂ And S_Five , S_Three And S₆ Both upper and lower transistors S set in each carrier period to prevent simultaneous ON of₁ And S_Four , S₂ And S_Five , S_Three And S₆ Effect of the simultaneous off time (hereinafter referred to as dead time) (the output voltage determined from the duty ratio of the drive signal is always (dead time) × V_DC/ T (V_DCIs the voltage of the DC power source 1 and T is the carrier cycle). In order to correct the deviation of the actual voltage), the arithmetic device 3B uses the positive / negative polarity value of each phase current detected by the current detectors 5 and 6 Upper and lower transistors S₁ And S_Four , S₂ And S_Five , S_Three And S₆ It is also possible to make the output terminal voltage value of each phase more exact the same by correcting the on / off ratio of the. That is, since it can be determined whether the output voltage is shifted to the plus side or the minus side depending on the polarity of the motor current, if the current detectors 5 and 6 determine that the motor current of the phase is positive, the dead voltage is dead to the minus side. Since the output voltage shifts by the amount of time, conversely, the ON width of the upper transistor is increased by the dead time to cancel the shift, and if the motor current is determined to be negative, the ON width of the upper transistor is reversed. Is reduced by the dead time.
[0041]
  The zero voltage output to the brushless DC motor 14 is performed as described above, and for example, based on the instantaneous detected current values at the same time of the V phase and the W phase detected by the current detectors 5 and 6 at the beginning of the zero voltage output. In the section [Means for Solving the Problems]WhoThe rotor speed and the rotor phase value (phase induced voltage phase value) of the brushless DC motor 14 are detected by the method. After detection, an appropriate output voltage is calculated by the arithmetic device 3B based on the detected rotor speed and the rotor phase value (phase induced voltage phase value), and the voltage is output to the brushless DC motor 14 and pulled into synchronous operation. Good.
[0042]
  Next, a third embodiment of the present invention will be described. The configuration is the same as in FIG. 6 and FIGS. 7 to 10 shown as the second embodiment. Until the zero voltage output to the brushless DC motor 14 is divided into q-axis current and d-axis current, the vibration of the motor current converges to zero and the d-axis current converges to a negative value corresponding to the rotor speed. The motor current at the time of convergence is detected by the current detectors 5 and 6, for example, based on the instantaneous detected current values at the same time in the V phase and the W phase [means for solving the problems] )WhoBy this method, the rotor speed and rotor phase value (phase induced voltage phase value) of the brushless DC motor 14 are detected. Also, the confirmation of the motor current convergence state is made by determining whether a preset time has elapsed after the start of zero voltage output, or by detecting the fluctuation amount of the detected effective current (see FIG. 12) and / or detecting it. It can be determined by the amount of fluctuation of each phase current phase value.
[0043]
7 and FIG. 10, in the state of the on / off drive signal to the semiconductor switching element group 2 for making the output terminal voltage value of each phase the same, FIG. 7 and FIG. In order to avoid this because the load is concentrated, it is conceivable that the on / off drive signals to the semiconductor switching element group 2 are alternately switched between FIGS. 7 and 8 at appropriate time intervals.
[0044]
  Next, a fourth embodiment of the present invention will be described. This explains the rotor speed of the brushless DC motor 14 in the section [Means for Solving the Problems] with respect to the third embodiment.WhoThe point of detection differs depending on the method.
[0045]
【The invention's effect】
  As described above, the present invention has the following effects.
  NonFor a brushless DC motor that does not have rotor position detection means directly connected to a synchronously rotating motor, a stable motor current can be started in a short time with an inexpensive arithmetic unit, and the brushless DC motor starts without stopping. And can be drawn into synchronous operation.
[0046]
  ProlapseFor a brushless DC motor that does not have rotor position detection means that is directly connected to the motor that is in rotation, control the output terminal voltage value to the motor from the non-energized state so that all three phases are the same, and output the voltage to the motor. In addition, by using the motor current values obtained from the current detectors for at least two of the three phases at this time, information necessary for pulling in the synchronous operation as it is without stopping the rotation of the brushless DC motor. Since the rotor speed and the rotor phase value (phase induced voltage phase value) of the brushless DC motor can be detected, the brushless DC motor during the step-out rotation is directly pulled into the synchronous operation without stopping the rotation. be able to.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a brushless DC motor driving apparatus according to a first embodiment of the present invention.
FIG. 2 is a diagram illustrating movement of a q-axis current and a d-axis current when a motor current is stably started.
FIG. 3 is a diagram illustrating movements of an output voltage q-axis component and a d-axis component when a motor current is stably started.
4 is a diagram showing the movement of the output voltage q-axis component and d-axis component in the embodiment of FIG. 1; FIG.
FIG. 5 is a vector diagram in which a motor current and each voltage are divided into a q-axis and a d-axis.
FIG. 6 is a configuration diagram of a brushless DC motor driving apparatus according to a second embodiment of the present invention.
7 is a diagram showing a state of an on / off drive signal to the semiconductor switching element group 2 for making the voltage values of the output terminals 11, 12, and 13 in FIG. 6 the same. FIG.
8 is a diagram showing a state of an on / off drive signal to the semiconductor switching element group 2 for making the voltage values of the output terminals 11, 12, and 13 in FIG. 6 the same. FIG.
9 is a diagram showing a state of an on / off drive signal to the semiconductor switching element group 2 for making the voltage values of the output terminals 11, 12, and 13 in FIG. 6 the same.
10 is a diagram showing a state of an on / off drive signal to a semiconductor switching element group for making the voltage values of output terminals 11, 12, and 13 in FIG. 6 the same.
FIG. 11 is a diagram showing a q-axis current waveform and a d-axis current waveform at the beginning of zero voltage output.
FIG. 12 is a diagram showing how the q-axis current waveform and the d-axis current waveform converge when zero voltage is output.
FIG. 13 is a diagram showing a configuration example of a conventional brushless DC motor driving apparatus.
[Explanation of symbols]
1 DC power supply
2 Semiconductor switching element group
3A, 3B arithmetic unit
4 Drive circuit section
5,6 Current detector
7, 8, 9 Armature coil
10 Rotor
11, 12, 13 Output terminal
14 Brushless DC motor
S₁ ~ S₆     Transistor

Claims (2)

In the drive device of the brushless DC motor in the non-energized rotation state,
A rotor speed detecting means and a rotor phase detecting means of a brushless DC motor;
Based on the rotor speed detection value and the rotor phase detection value, and the set target current and the start time during which the rotor speed can be assumed to be constant, the operation starts when the target current is reached at the start time and at a constant increase rate. Means for calculating the output voltage of each d axis and q axis at the time of reaching the target current and the phase difference on the dq axis between each output voltage;
Means for calculating a frequency obtained by dividing the phase difference by the activation time;
Voltage output is started by the output voltage at the start of the operation, and the voltage is output at a frequency obtained by adding the calculated frequency to the motor synchronous frequency corresponding to the rotor speed detection value for the start time, and after the start time A brushless DC motor drive device comprising means for returning to a motor synchronous frequency corresponding to the detected rotor speed and entering synchronous operation . In a brushless DC motor driving apparatus in an asynchronous rotation state,
Means for making the brushless DC motor non-energized;
A rotor speed detecting means and a rotor phase detecting means of a brushless DC motor;
Based on the rotor speed detection value and the rotor phase detection value, and the set target current and the start time during which the rotor speed can be assumed to be constant, the operation starts when the target current is reached at the start time and at a constant increase rate. Means for calculating the output voltage of each d axis and q axis at the time of reaching the target current and the phase difference on the dq axis between each output voltage;
Means for calculating a frequency obtained by dividing the phase difference by the activation time;
Voltage output is started by the output voltage at the start of the operation, and the voltage is output at a frequency obtained by adding the calculated frequency to the motor synchronous frequency corresponding to the rotor speed detection value for the start time, and after the start time A brushless DC motor drive device comprising means for returning to a motor synchronous frequency corresponding to the detected rotor speed and entering synchronous operation .

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