JP3930264B2

JP3930264B2 - Magnetic bearing control device

Info

Publication number: JP3930264B2
Application number: JP2001138622A
Authority: JP
Inventors: 俊治落合; 透大須賀; 宏桑山; 慎介遠藤
Original assignee: Ebara Corp
Current assignee: Ebara Corp
Priority date: 2001-05-09
Filing date: 2001-05-09
Publication date: 2007-06-13
Anticipated expiration: 2021-05-09
Also published as: JP2002333019A

Description

【０００１】
【発明の属する技術分野】
本発明は、電磁石の磁気吸引力を利用して回転軸等の被浮上体を非接触で浮上支持する磁気軸受を制御する磁気軸受制御装置に関し、特に磁気軸受を構成する一対或いは複数対の電磁石に供給するバイアス定電流を調整する磁気軸受制御装置に関するものである。
【０００２】
【従来の技術】
磁気軸受は、回転軸等の被浮上体を非接触で支持できる軸受であることから、例えばターボ分子ポンプ等に用いて高速回転運動が可能となり、軸受の摩耗という問題が生ぜず、又潤滑油等を必要としないのでメンテナンスフリーである等の種々の特徴を有している。係る磁気軸受には、回転軸を半径方向に浮上位置制御するラジアル能動磁気軸受、回転軸を軸方向に浮上位置制御するアキシャル能動磁気軸受がある。これら従来の磁気軸受を用いた磁気軸受制御装置の一部分の構成例を図１に示す。
【０００３】
図１において、１は回転軸等の被浮上体であり、該被浮上体１の浮上位置は、該被浮上体１に対向して配置された変位センサ４、４により検出され、センサ回路５により変位電気信号に変換され、位相補正回路６によりＰＩＤ（比例・積分・微分）処理された後、定電流回路７ａ、７ｂに入力され、被浮上体１に対向して配置された一対の電磁石２、２の磁極コイル３Ｐ、３Ｎにその変位量のずれを修正する磁気吸引力Ｐ_P、Ｐ_Nに相当する励磁電流となって供給され、被浮上体１は電磁石２と電磁石２の間に磁気浮上支持される。
【０００４】
磁気軸受の電磁石２においては、一般的に磁気吸引力が磁極コイルに流れる電流の２乗に比例することが知られているので対向する電磁石２、２の磁極コイル３Ｐ、３Ｎにある一定のバイアス電流Ｉ_BP、Ｉ_BNを供給し、センサ回路５からの変位電気信号に対して電磁石２、２の磁気吸引力Ｐ_P、Ｐ_Nが直線的に比例関係になるようにしている。
【０００５】
図２に示すように、変位量が中心点０より＋方向、或いは−方向に変位した場合、対向する電磁石２、２の磁極コイル３Ｐ、３Ｎのそれぞれのバイアス電流Ｉ_BP、Ｉ_BNは増減し、結果として磁気吸引力Ｐ_P、Ｐ_Nの合成の磁気吸引力はセンサ回路５からの変位電気信号に直線的に比例するようになる。また、変位量が０の場合のバイアス定電流Ｉ_BOは、各回路構成における電気的な部品のばらつきや、被浮上体１の重量又は形状或いは電磁石２の構造の違いや、被浮上体１の浮上向きによって磁気軸受にその重力が加わる場合等において、良好な直線性が得られるようにバイアス電流調整器８、８等によってバイアス定電流Ｉ_BOが調整されていた。
【０００６】
上記のようなバイアス電流調整器８によるバイアス定電流調整方法は、磁気軸受の制御装置や被浮上体や磁気軸受構成が変わる異機種毎に手動で調整を行う必要があり、特に電磁石２の数が多い多軸制御の磁気軸受装置においてはその調整に多大な労力を要していた。更に、磁気軸受を用いたターボ分子ポンプ等の場合は、ポンプの取り付け姿勢に自由度が求められ、全ての取付姿勢において磁気軸受を構成する電磁石に良好なバイアス定電流を流すためには全ての電磁石に被浮上体の重量を考慮したバイアス定電流を供給する必要があり、結果として必要以上の電流が流れ、磁気軸受部の発熱やコントローラの大型化を招くという問題がある。
【０００７】
【発明が解決しようとする課題】
本発明は上述の点に鑑みてなされたもので、同一のコントローラで異機種の磁気軸受装置及び磁気軸受装置の設置姿勢に対応して容易に磁気軸受を構成する電磁石のバイアス電流の調整ができ、且つ該バイアス電流値を必要最小の最適な状態に調整できる小型で、磁気軸受部の発熱量が少なくできる磁気軸受制御装置を提供することを目的とする。
【００１２】
上記課題を解決するため請求項１に記載の発明は、被浮上体を磁気浮上支持する一対或いは複数対の電磁石、及び該被浮上体の浮上位置を検出する一対或いは複数対の変位センサを具備する単数又は複数の磁気軸受ユニットと、該電磁石に一定のバイアス電流を流して被浮上体を安定浮上制御させる定電流回路と、変位センサの出力信号に基いて浮上体を所定位置に浮上支持するように電磁石の励磁電流を制御する制御ループを具備する磁気軸受制御装置において、コントローラ、磁気軸受ユニットの一対或いは複数対の電磁石に流れるバイアス電流を検出する電流検出回路、定電流回路から供給されるバイアス電流を調整する定電流調整回路を設け、コントローラは該電流検出回路で検出したバイアス電流値が適正か否かを判断し、バイアス電流を予め決められた最適定電流値になるように定電流調整回路を介して調整する機能を具備することを特徴とする。
【００１３】
上記のようにコントローラにより、電流検出回路で検出したバイアス電流値が適正か否かを判断し、バイアス電流を予め決められた最適電流値になるように定電流調整回路を介して調整するので、磁気軸受ユニットの電磁石のバイアス電流を最適定電流値に容易に調整することができる。また、バイアス電流値を磁気軸受ユニットの電磁石に流れるバイアス電流をフィードバックすることでバイアス電流値が目標値に達しているか否かを判断し自動調整するので、コントローラと磁気軸受装置の系に固体差があってもバイアス電流値を自動的に補正できるのである。
【００１４】
請求項２に記載の発明は、被浮上体を磁気浮上支持する一対或いは複数対の電磁石、及び該被浮上体の浮上位置を検出する一対或いは複数対の変位センサを具備する単数又は複数の磁気軸受ユニットと、該電磁石に一定のバイアス電流を流して被浮上体を安定浮上制御させる定電流回路と、変位センサの出力信号に基いて浮上体を所定位置に浮上支持するように電磁石の励磁電流を制御する制御ループを具備する磁気軸受制御装置において、コントローラ、磁気軸受ユニットの一対或いは複数対の電磁石に流れるバイアス電流を検出する電流検出回路、定電流回路から供給されるバイアス電流を調整する定電流調整回路を設け、コントローラは各電流検出回路の検出電流値を読み込み、予め記憶された各磁気軸受ユニットの被浮上体の浮上向きにおける磁気軸受ユニットの各電磁石に流れるバイアス電流データと比較し、被浮上体の浮上向きを解析し、該解析結果に基いて各定電流回路からのバイアス電流が被浮上体の浮上している向きに対して予め定めた最適値になるように定電流調整回路を介して調整する機能を具備することを特徴とする。
【００１５】
上記のようにコントローラにより、磁気軸受ユニットの被浮上体の浮上向きを解析し、該解析結果に基いて各定電流回路からのバイアス電流が被浮上体の浮上している向きに対して予め定めた最適値になるようにバイアス定電流を調整するので、例えば複数の磁気軸受ユニットを具備するターボ分子ポンプ等においてどのような取付姿勢であっても、電磁石に最適なバイアス電流を流すことができ、必要以上のバイアス電流による磁気軸受の発熱を防止できる。また、必要最小限のバイアス電流で制御可能なため、磁気軸受ユニットの電磁石の励磁に必要な電源容量も小さくできる。また、バイアス電流値を磁気軸受ユニットの電磁石に流れるバイアス電流をフィードバックし、予め記憶された各磁気軸受ユニットの被浮上体の浮上向きにおける電磁石に流れるバイアス電流データと比較し、被浮上体の浮上向きを解析し、該解析結果に基いて各定電流回路からのバイアス電流が被浮上体の浮上している向きに対して予め定めた最適値になるように調整するので、コントローラと磁気軸受装置の系に固体差があってもバイアス電流値を自動的に補正できる。
【００１６】
請求項３に記載の発明は、請求項２に記載の磁気軸受制御装置において、制御ループを切断させるループ切断手段を設け、コントローラは磁気軸受ユニットの電磁石に流れる電流をバイアス電流のみに固定する機能を具備することを特徴とする。
【００１７】
上記のようにコントローラが磁気軸受ユニットの電磁石に流れる電流をバイアス電流のみに固定する機能を具備するので、バイアス電流の調整が他の制御電流等に影響されることなくできるので、バイアス電流の調整が容易で且つ精度良くできる。
【００１８】
請求項４に記載の発明は、請求項１乃至３のいずれか１項に記載の磁気軸受装置において、コントローラは前記定電流調整回路を介して調整したバイアス電流値を記憶する記憶装置を具備し、被浮上体の浮上制御に該記憶装置に記憶したバイアス電流値を利用することを特徴とする。
【００１９】
上記のようにコントローラは記憶装置に記憶している定電流調整回路を介して調整したバイアス電流値を利用して被浮上体の浮上制御を行うので、一度バイアス電流の調整を行うと以後のバイアス電流の調整が不要或いは短縮できる。
【００２０】
【発明の実施の形態】
以下、本発明の実施の形態例を図面に基いて説明する。図３は本発明に係る磁気軸受制御装置の構成例を示す図であり、本磁気軸受制御装置は、１軸方向の磁気軸受を制御する磁気軸受制御装置の構成例を示す。図３において、図１と同一符号を付した部分は同一又は相当部分を示す。図３において、９ａ、９ｂは定電流調整回路、１０ａ、１０ｂは電流検出回路、１１は制御回路、１２は不揮発性記憶装置（ＥＥＰＲＯＭ）、１３はアナログスイッチである。ここで、電磁石２、２と、変位センサ４、４で被浮上体１を磁気浮上させる磁気軸受ユニットを構成する。また、制御回路１１と、不揮発性記憶装置１２で制御コントローラを構成する。
【００２１】
上記構成の磁気軸受制御装置において初期状態では、アナログスイッチ１３は制御回路１１により開き、制御ループを開放しており、制御回路１１は不揮発性記憶装置１２に記憶されている初期状態のバイアス定電流値を読み込み定電流調整回路９ａ、９ｂにその値を出力する。その後定電流調整回路９ａ、９ｂは定電流回路７ａ、７ｂを介して、電磁石２、２の磁極コイル３Ｐ、３Ｎに設定されたバイアス電流を供給する。この時アナログスイッチ１３が制御ループを開放しているため、磁極コイル３Ｐ、３Ｎには定電流調整回路９ａ、９ｂにて設定されたバイアス電流のみが流れる。
【００２２】
このバイアス電流を電流検出回路１０ａ、１０ｂにて検出し、その電流検出値を制御回路１１に入力すると共に、制御回路１１は不揮発性記憶装置１２に予め設定記憶されている目標電流値との差を計算し、該目標電流値が磁極コイル３Ｐ、３Ｎに流れるように、定電流調整回路９ａ、９ｂに新たな指示値を出力する。電流検出回路１０ａ、１０ｂで検出した検出電流値が上記目標電流値と等しくなると、制御回路１１はアナログスイッチ１３を閉じ、制御ループを閉じる。これにより、電磁石２、２による被浮上体１の磁気浮上を開始する。
【００２３】
変位センサ４及びセンサ回路５からの変位電気信号は位相補正回路６によりＰＩＤ制御され、定電流回路７ａ、７ｂに入力され、被浮上体１の変位量に相当する励磁電流が磁極コイル３Ｐ、３Ｎに加減され被浮上体１を磁気浮上させるように制御が開始される。被浮上体１の磁気浮上後、該被浮上体１に軸重量が図のように加わった場合は、重量Ｍの力を相殺するために磁極コイル３Ｐに流れる励磁電流が増加し磁極コイル３Ｎに流れる励磁電流が減少する様に制御が行われる。その結果、電流検出回路１０ａと電流検出回路１０ｂにて検出される電流値が異なり、この値を制御回路１１が読み込むことで現在の被浮上体１の浮上方向、即ち磁気軸受ユニットの設置方向が判定できる。
【００２４】
不揮発性記憶装置１２には、上記初期状態のバイアス定電流値及び目標電流値の他に、被浮上体１の浮上方向（磁気軸受の設置方向）に対応する電磁石２へのバイアス定電流が記憶されており、制御回路１１は不揮発性記憶装置１２に記憶されている各浮上向きでのバイアス定電流値を参照し、電流検出回路１０ａ、１０ｂの電流検出値に合致する現在の浮上方向を探し出し、その浮上状態での最適のバイアス定電流値を不揮発性記憶装置１２により再度読み込んで定電流調整回路９ａ、９ｂに新たな目標電流値となるバイアス定電流値を出力する。これにより磁極コイル３Ｐ、３Ｎに流れるバイアス電流は増減し、結果として電磁石２はセンサ変位電気信号に直線的に比例した磁気吸引力を発生することが可能となる。
【００２５】
また、上記により最適に調整された時の定電流調整回路に対する補正値は、不揮発性記憶装置１２に保存し、次回浮上時にこのデータを利用して前記の調整手順を短縮するようにしてもよい。
【００２６】
図３に示す構成の磁気軸受制御装置は、１軸方向の磁気軸受を制御する場合であるが、１軸以上の複数の制御軸を備える磁気軸受装置に関しても同様に構成できる。図４は複数（図では３つ）の磁気軸受制御装置１５の磁気軸受ユニット１４のバイアス電流を１つの制御コントローラ１６で調整する場合である。
【００２７】
図４において、制御コントローラ１６は制御回路１１と不揮発性記憶装置（ＥＥＰＲＯＭ）１２で構成される。また、各磁気軸受制御装置１５は定電流回路７ａ、７ｂ、定電流調整回路９ａ、９ｂ、電流検出回路１０ａ、１０ｂ、アナログスイッチ１３で構成される。また、各磁気軸受制御装置１５にはそれぞれ磁気軸受ユニット１４が接続されている。磁気軸受ユニット１４は図示は省略するが図３に示すように、被浮上体１に対向して配置された一対の電磁石２、２、変位センサ４、４で構成される。
【００２８】
そして電磁石２、２の磁極コイル３Ｐ、３Ｎは電流検出回路１０ａ、１０ｂを介して定電流回路７ａ、７ｂに接続され、変位センサ４、４の出力は図３に示すようにセンサ回路５に入力され、センサ回路５の出力は位相補正回路６に入力され、位相補正回路６の出力はアナログスイッチ１３を介して定電流回路７ａ、７ｂに入力されるようになっている。バイアス定電流の調整方法は、図３の場合と同様であるからその説明は省略する。
【００２９】
【発明の効果】
以上、説明したように各請求項の発明によれば、下記のような優れた効果が得られる。
【００３２】
請求項１に記載の発明によれば、コントローラにより、電流検出回路で検出したバイアス電流値が適正か否かを判断し、バイアス電流を予め決められた最適電流値になるように定電流調整回路を介して調整するので、磁気軸受ユニットの電磁石のバイアス電流を最適定電流値に容易に調整することができる。また、バイアス電流値を磁気軸受ユニットの電磁石に流れるバイアス電流をフィードバックすることでバイアス電流値が目標値に達しているか否かを判断し自動調整するので、コントローラと磁気軸受装置の系に固体差があってもバイアス電流値を自動的に補正できるのである。
【００３３】
請求項２に記載の発明によれば、コントローラにより、磁気軸受ユニットの被浮上体の浮上向きを解析し、該解析結果に基いて各定電流回路からのバイアス電流が被浮上体の浮上している向きに対して予め定めた最適値になるようにバイアス定電流を調整するので、例えば複数の磁気軸受ユニットを具備するターボ分子ポンプ等においてどのような取付姿勢であっても、電磁石に最適なバイアス電流を流すことができ、必要以上のバイアス電流による磁気軸受の発熱を防止できる。また、必要最小限のバイアス電流で制御可能なため、磁気軸受ユニットの電磁石の励磁に必要な電源容量も小さくできる。また、バイアス電流値を磁気軸受ユニットの電磁石に流れるバイアス電流をフィードバックし、予め記憶された各磁気軸受ユニットの被浮上体の浮上向きにおける電磁石に流れるバイアス電流データと比較し、被浮上体の浮上向きを解析し、該解析結果に基いて各定電流回路からのバイアス電流が被浮上体の浮上している向きに対して予め定めた最適値になるように調整するので、コントローラと磁気軸受装置の系に固体差があってもバイアス電流値を自動的に補正できる。
【００３４】
請求項３に記載の発明によれば、コントローラが磁気軸受ユニットの電磁石に流れる電流をバイアス電流のみに固定する機能を具備するので、バイアス電流の調整が他の制御電流等に影響されることなくできるので、バイアス電流の調整が容易で且つ精度良くできる。
【００３５】
請求項４に記載の発明によれば、コントローラは記憶装置に記憶している定電流調整回路を介して調整したバイアス電流値を利用して被浮上体の浮上制御を行うので、一度バイアス電流の調整を行うと以後のバイアス電流の調整が不要或いは短縮できる。
【図面の簡単な説明】
【図１】従来の磁気軸受制御装置の構成例を示す図である。
【図２】磁気軸受の磁極コイルに流れる励磁電流と被浮上体の変位量及び被浮上体に及ぼす磁気吸引力の関係を示す図である。
【図３】本発明に係る磁気軸受制御装置の構成例を示す図である。
【図４】本発明に係る磁気軸受制御装置の構成例を示す図である。
【符号の説明】
１被浮上体
２電磁石
３Ｐ、３Ｎ磁極コイル
４変位センサ
５センサ回路
６位相補正回路
７ａ、７ｂ定電流回路
８バイアス電流調整器
９ａ、９ｂ定電流調整回路
１０ａ、１０ｂ電流検出回路
１１制御回路
１２不揮発性記憶装置
１３アナログスイッチ
１４磁気軸受ユニット
１５磁気軸受制御装置
１６制御コントローラ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic bearing control device that controls a magnetic bearing that floats and supports a floating body such as a rotating shaft in a non-contact manner by using a magnetic attraction force of an electromagnet, and in particular, a pair or a plurality of pairs of electromagnets constituting the magnetic bearing. The present invention relates to a magnetic bearing control device that adjusts a constant bias current supplied to a magnetic field.
[0002]
[Prior art]
A magnetic bearing is a bearing that can support a floating body such as a rotating shaft in a non-contact manner. For example, it can be used for a turbo molecular pump or the like, and can be rotated at high speed. Therefore, it has various features such as maintenance-free. Such magnetic bearings include a radial active magnetic bearing that controls the floating position of the rotating shaft in the radial direction, and an axial active magnetic bearing that controls the floating position of the rotating shaft in the axial direction. A configuration example of a part of a magnetic bearing control device using these conventional magnetic bearings is shown in FIG.
[0003]
In FIG. 1, reference numeral 1 denotes a floating body such as a rotating shaft, and the floating position of the floating body 1 is detected by displacement sensors 4, 4 arranged facing the floating body 1, and a sensor circuit 5. A pair of electromagnets which are converted into displacement electric signals by the phase correction circuit 6 and subjected to PID (proportional / integral / differential) processing by the phase correction circuit 6 and then input to the constant current circuits 7a and 7b and arranged to face the floating body 1 The magnetic poles 3P and 3N are supplied with excitation currents corresponding to the magnetic attractive forces P _P and P _N for correcting the displacement of the displacement amount, and the levitated body 1 is interposed between the electromagnet 2 and the electromagnet 2. Supported by magnetic levitation.
[0004]
In the electromagnet 2 of the magnetic bearing, it is generally known that the magnetic attraction force is proportional to the square of the current flowing in the magnetic pole coil, so that a constant bias is present in the magnetic pole coils 3P, 3N of the opposing electromagnets 2, 2. Currents I _BP and I _BN are supplied so that the magnetic attractive forces P _P and P _{N of the} electromagnets 2 and 2 are linearly proportional to the displacement electric signal from the sensor circuit 5.
[0005]
As shown in FIG. 2, when the displacement amount is displaced in the + direction or the − direction from the center point 0, the respective bias currents I _BP and I _BN of the opposing electromagnets 2 and 2 magnetic pole coils 3P and 3N increase or decrease. As a result, the combined magnetic attractive force of the magnetic attractive forces P _P and P _N is linearly proportional to the displacement electric signal from the sensor circuit 5. In addition, the bias constant current I _BO when the displacement amount is 0 is the variation of electrical parts in each circuit configuration, the weight or shape of the floating body 1 or the structure of the electromagnet 2, The bias constant current I _BO has been adjusted by the bias current adjusters 8, 8 and the like so as to obtain good linearity when the gravity is applied to the magnetic bearing by the flying direction.
[0006]
The bias constant current adjustment method using the bias current adjuster 8 as described above requires manual adjustment for each different model in which the magnetic bearing control device, the floating body, and the magnetic bearing configuration are changed. In many multi-axis control magnetic bearing devices, much effort is required for the adjustment. Furthermore, in the case of a turbo molecular pump or the like using a magnetic bearing, a degree of freedom is required for the mounting posture of the pump, and in order to allow a good bias constant current to flow through the electromagnets constituting the magnetic bearing in all mounting postures. There is a need to supply a constant bias current in consideration of the weight of the floating body to the electromagnet. As a result, an unnecessarily large current flows, resulting in a problem of heat generation of the magnetic bearing portion and an increase in the size of the controller.
[0007]
[Problems to be solved by the invention]
The present invention has been made in view of the above points, and it is possible to easily adjust the bias current of the electromagnet constituting the magnetic bearing in accordance with the installation posture of different types of magnetic bearing devices and magnetic bearing devices with the same controller. Another object of the present invention is to provide a magnetic bearing control device that can adjust the bias current value to a minimum and optimum state and can reduce the amount of heat generated in the magnetic bearing portion.
[0012]
In order to solve the above problems, the invention described in claim 1 includes a pair or a plurality of pairs of electromagnets for magnetically levitating and supporting a floating body, and a pair or a plurality of pairs of displacement sensors for detecting a floating position of the floating body. One or a plurality of magnetic bearing units, a constant current circuit for controlling the levitated body stably by supplying a constant bias current to the electromagnet, and levitating and supporting the levitating body at a predetermined position based on an output signal of the displacement sensor. Thus, in the magnetic bearing control device having a control loop for controlling the exciting current of the electromagnet, the controller, the current detecting circuit for detecting the bias current flowing through the pair or plural pairs of electromagnets of the magnetic bearing unit, and the constant current circuit are supplied. A constant current adjustment circuit that adjusts the bias current is provided, and the controller determines whether or not the bias current value detected by the current detection circuit is appropriate. Characterized by including a function to adjust via the constant current regulating circuit so that a current to a predetermined optimum constant current value.
[0013]
As described above, the controller determines whether or not the bias current value detected by the current detection circuit is appropriate, and adjusts the bias current via the constant current adjustment circuit so as to become a predetermined optimum current value. The bias current of the electromagnet of the magnetic bearing unit can be easily adjusted to the optimum constant current value. Also, since the bias current value is fed back and fed back to the electromagnet of the magnetic bearing unit to determine whether or not the bias current value has reached the target value, it is automatically adjusted. Even if there is, the bias current value can be automatically corrected.
[0014]
The invention according to claim 2 is a single or a plurality of magnets including a pair or a plurality of pairs of electromagnets for magnetically levitating and supporting a floating body, and a pair or a plurality of pairs of displacement sensors for detecting a floating position of the floating body. A bearing unit, a constant current circuit that allows a constant bias current to flow through the electromagnet to stably control the levitated body, and an exciting current of the electromagnet so that the levitating body is levitated and supported at a predetermined position based on the output signal of the displacement sensor. In a magnetic bearing control device comprising a control loop for controlling the current, a controller, a current detection circuit for detecting a bias current flowing in one or more pairs of electromagnets of the magnetic bearing unit, and a constant current for adjusting a bias current supplied from a constant current circuit. A current adjustment circuit is provided, the controller reads the detected current value of each current detection circuit, and the floating direction of the floating body of each magnetic bearing unit stored in advance Compared with the bias current data that flows to each electromagnet of the magnetic bearing unit in, analyze the floating direction of the floating body, and based on the analysis results, the bias current from each constant current circuit is floating direction of the floating body Is provided with a function of adjusting through a constant current adjusting circuit so as to have a predetermined optimum value.
[0015]
As described above, the controller analyzes the levitation direction of the floating body of the magnetic bearing unit, and the bias current from each constant current circuit is determined in advance with respect to the floating direction of the levitation body based on the analysis result. The bias constant current is adjusted so that the optimum value can be obtained, so that the optimum bias current can be applied to the electromagnet regardless of the mounting orientation, for example, in a turbomolecular pump equipped with a plurality of magnetic bearing units. The heat generation of the magnetic bearing due to the bias current more than necessary can be prevented. In addition, since control is possible with the minimum necessary bias current, the power supply capacity necessary for exciting the electromagnet of the magnetic bearing unit can be reduced. Also, the bias current value is fed back to the bias current flowing to the electromagnet of the magnetic bearing unit, and compared with the bias current data flowing to the electromagnet in the floating direction of the floating body of each magnetic bearing unit stored in advance, Since the direction is analyzed and the bias current from each constant current circuit is adjusted based on the analysis result so that the bias current is set to a predetermined optimum value with respect to the flying direction of the floating body, the controller and the magnetic bearing device The bias current value can be automatically corrected even if there is a difference between individual systems.
[0016]
According to a third aspect of the present invention, in the magnetic bearing control device according to the second aspect , a loop cutting means for cutting the control loop is provided, and the controller has a function of fixing the current flowing through the electromagnet of the magnetic bearing unit only to the bias current. It is characterized by comprising.
[0017]
Since the controller has the function of fixing the current flowing in the electromagnet of the magnetic bearing unit only to the bias current as described above, the adjustment of the bias current can be performed without being influenced by other control currents, etc. Is easy and accurate.
[0018]
According to a fourth aspect of the invention, in the magnetic bearing device according to any one of claims 1 to 3, the controller comprises a storage device for storing bias current values adjusted via the constant current regulating circuit The bias current value stored in the storage device is used for the floating control of the floating body.
[0019]
As described above, the controller controls the floating body using the bias current value adjusted via the constant current adjustment circuit stored in the storage device. Therefore, once the bias current is adjusted, the subsequent bias is adjusted. Current adjustment is unnecessary or shortened.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 is a diagram showing a configuration example of a magnetic bearing control device according to the present invention, and this magnetic bearing control device shows a configuration example of a magnetic bearing control device that controls a magnetic bearing in one axial direction. In FIG. 3, the parts denoted by the same reference numerals as those in FIG. 1 indicate the same or corresponding parts. In FIG. 3, 9a and 9b are constant current adjusting circuits, 10a and 10b are current detection circuits, 11 is a control circuit, 12 is a nonvolatile memory device (EEPROM), and 13 is an analog switch. Here, the electromagnets 2 and 2 and the displacement sensors 4 and 4 constitute a magnetic bearing unit for magnetically levitating the levitated body 1. The control circuit 11 and the nonvolatile storage device 12 constitute a control controller.
[0021]
In the initial state of the magnetic bearing control device having the above configuration, the analog switch 13 is opened by the control circuit 11 and the control loop is opened. The control circuit 11 is the initial bias constant current stored in the nonvolatile memory device 12. The value is read and the value is output to the constant current adjusting circuits 9a and 9b. Thereafter, the constant current adjusting circuits 9a and 9b supply bias currents set to the magnetic pole coils 3P and 3N of the electromagnets 2 and 2 through the constant current circuits 7a and 7b. At this time, since the analog switch 13 opens the control loop, only the bias current set by the constant current adjusting circuits 9a and 9b flows through the magnetic pole coils 3P and 3N.
[0022]
The bias current is detected by the current detection circuits 10 a and 10 b, and the current detection value is input to the control circuit 11, and the control circuit 11 is different from the target current value preset and stored in the nonvolatile memory device 12. And a new instruction value is output to the constant current adjustment circuits 9a and 9b so that the target current value flows through the magnetic pole coils 3P and 3N. When the detected current value detected by the current detection circuits 10a and 10b becomes equal to the target current value, the control circuit 11 closes the analog switch 13 and closes the control loop. Thereby, the magnetic levitation of the levitated body 1 by the electromagnets 2 and 2 is started.
[0023]
Displacement electrical signals from the displacement sensor 4 and the sensor circuit 5 are PID-controlled by the phase correction circuit 6 and input to the constant current circuits 7a and 7b, and an excitation current corresponding to the displacement amount of the floating body 1 is applied to the magnetic pole coils 3P and 3N. The control is started so that the levitated body 1 is magnetically levitated. When the shaft weight is applied to the levitated body 1 after the magnetic levitation of the levitated body 1, the exciting current flowing in the magnetic pole coil 3P increases to cancel the force of the weight M, and the magnetic pole coil 3N Control is performed so that the exciting current that flows is reduced. As a result, the current values detected by the current detection circuit 10a and the current detection circuit 10b are different, and when the control circuit 11 reads this value, the current floating direction of the floating body 1, that is, the installation direction of the magnetic bearing unit is determined. Can be judged.
[0024]
In the nonvolatile memory device 12, in addition to the bias constant current value and the target current value in the initial state, a bias constant current to the electromagnet 2 corresponding to the flying direction of the floating body 1 (magnetic bearing installation direction) is stored. The control circuit 11 refers to the bias constant current value in each levitation direction stored in the non-volatile storage device 12, and finds the current levitation direction that matches the current detection values of the current detection circuits 10a and 10b. Then, the optimum bias constant current value in the floating state is read again by the nonvolatile memory device 12, and a bias constant current value that becomes a new target current value is output to the constant current adjustment circuits 9a and 9b. As a result, the bias current flowing through the magnetic pole coils 3P and 3N increases and decreases, and as a result, the electromagnet 2 can generate a magnetic attractive force linearly proportional to the sensor displacement electric signal.
[0025]
In addition, the correction value for the constant current adjustment circuit when optimally adjusted as described above may be stored in the nonvolatile storage device 12, and the adjustment procedure may be shortened using this data at the next ascent. .
[0026]
The magnetic bearing control device having the configuration shown in FIG. 3 is a case where a magnetic bearing in one axial direction is controlled, but a magnetic bearing device including a plurality of control shafts having one or more axes can be similarly configured. FIG. 4 shows a case where the bias current of the magnetic bearing units 14 of a plurality (three in the figure) of the magnetic bearing control device 15 is adjusted by one controller 16.
[0027]
In FIG. 4, the controller 16 includes a control circuit 11 and a nonvolatile memory device (EEPROM) 12. Each magnetic bearing control device 15 includes constant current circuits 7a and 7b, constant current adjustment circuits 9a and 9b, current detection circuits 10a and 10b, and an analog switch 13. Each magnetic bearing control device 15 is connected to a magnetic bearing unit 14. Although not shown in the figure, the magnetic bearing unit 14 is composed of a pair of electromagnets 2 and 2 and displacement sensors 4 and 4 disposed to face the floating body 1 as shown in FIG.
[0028]
The magnetic pole coils 3P and 3N of the electromagnets 2 and 2 are connected to the constant current circuits 7a and 7b via the current detection circuits 10a and 10b, and the outputs of the displacement sensors 4 and 4 are input to the sensor circuit 5 as shown in FIG. The output of the sensor circuit 5 is input to the phase correction circuit 6, and the output of the phase correction circuit 6 is input to the constant current circuits 7a and 7b via the analog switch 13. The method for adjusting the bias constant current is the same as in the case of FIG.
[0029]
【The invention's effect】
As described above, according to the invention of each claim, the following excellent effects can be obtained.
[0032]
According to the first aspect of the present invention, the controller determines whether or not the bias current value detected by the current detection circuit is appropriate, and the constant current adjustment circuit so that the bias current becomes a predetermined optimum current value. Therefore, the bias current of the electromagnet of the magnetic bearing unit can be easily adjusted to the optimum constant current value. Also, since the bias current value is fed back and fed back to the electromagnet of the magnetic bearing unit to determine whether or not the bias current value has reached the target value, it is automatically adjusted. Even if there is, the bias current value can be automatically corrected.
[0033]
According to the second aspect of the present invention, the controller analyzes the flying direction of the floating body of the magnetic bearing unit, and the bias current from each constant current circuit floats on the floating body based on the analysis result. The bias constant current is adjusted so as to have a predetermined optimum value for the direction in which it is placed, so it is optimal for an electromagnet regardless of the mounting orientation, for example, in a turbo molecular pump having a plurality of magnetic bearing units. A bias current can be passed, and heat generation of the magnetic bearing due to an excessive bias current can be prevented. In addition, since control is possible with the minimum necessary bias current, the power supply capacity necessary for exciting the electromagnet of the magnetic bearing unit can be reduced. Also, the bias current value is fed back to the bias current flowing to the electromagnet of the magnetic bearing unit, and compared with the bias current data flowing to the electromagnet in the floating direction of the floating body of each magnetic bearing unit stored in advance, Since the direction is analyzed and the bias current from each constant current circuit is adjusted based on the analysis result so that the bias current is set to a predetermined optimum value with respect to the flying direction of the floating body, the controller and the magnetic bearing device The bias current value can be automatically corrected even if there is a difference between individual systems.
[0034]
According to the invention described in claim 3 , since the controller has a function of fixing the current flowing in the electromagnet of the magnetic bearing unit only to the bias current, the adjustment of the bias current is not affected by other control currents or the like. Therefore, the bias current can be easily adjusted with high accuracy.
[0035]
According to the fourth aspect of the present invention, since the controller controls the levitating body using the bias current value adjusted via the constant current adjusting circuit stored in the storage device, the bias current is once adjusted. When the adjustment is performed, the subsequent adjustment of the bias current is unnecessary or can be shortened.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration example of a conventional magnetic bearing control device.
FIG. 2 is a diagram showing a relationship between an exciting current flowing in a magnetic pole coil of a magnetic bearing, a displacement amount of a floating body, and a magnetic attraction force exerted on the floating body.
FIG. 3 is a diagram showing a configuration example of a magnetic bearing control device according to the present invention.
FIG. 4 is a diagram showing a configuration example of a magnetic bearing control device according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Levitated body 2 Electromagnet 3P, 3N Magnetic pole coil 4 Displacement sensor 5 Sensor circuit 6 Phase correction circuit 7a, 7b Constant current circuit 8 Bias current regulator 9a, 9b Constant current adjustment circuit 10a, 10b Current detection circuit 11 Control circuit 12 Nonvolatile Memory device 13 Analog switch 14 Magnetic bearing unit 15 Magnetic bearing control device 16 Control controller

Claims

One or a plurality of pairs of electromagnets for magnetically levitating and supporting the floating body, and one or a plurality of magnetic bearing units including a pair or a plurality of pairs of displacement sensors for detecting the floating position of the floating body, A constant current circuit for controlling the levitated body stably by supplying a bias current; and a control loop for controlling the exciting current of the electromagnet so as to levitate and support the levitated body at a predetermined position based on an output signal of the displacement sensor. In the magnetic bearing control device provided,
A controller, a current detection circuit for detecting a bias current flowing in one or more pairs of electromagnets of the magnetic bearing unit, and a constant current adjustment circuit for adjusting a bias current supplied from the constant current circuit, wherein the controller detects the current A function of determining whether or not a bias current value detected by a circuit is appropriate and adjusting the bias current through the constant current adjustment circuit so as to become a predetermined optimum constant current value; Magnetic bearing control device.

One or a plurality of pairs of electromagnets for magnetically levitating and supporting the floating body, and one or a plurality of magnetic bearing units including a pair or a plurality of pairs of displacement sensors for detecting the floating position of the floating body, A constant current circuit for controlling the levitated body stably by supplying a bias current; and a control loop for controlling the exciting current of the electromagnet so as to levitate and support the levitated body at a predetermined position based on an output signal of the displacement sensor. In the magnetic bearing control device provided,
A controller, a current detection circuit for detecting a bias current flowing in a pair or a plurality of pairs of electromagnets of the magnetic bearing unit, and a constant current adjustment circuit for adjusting a bias current supplied from the constant current circuit, wherein the controller The detection current value of the detection circuit is read and compared with the bias current data flowing in each electromagnet of the magnetic bearing unit in the floating direction of the floating body of each magnetic bearing unit stored in advance, and the floating direction of the floating body is analyzed Then, the bias current from each constant current circuit is adjusted via the constant current adjustment circuit so that the bias current from each constant current circuit becomes a predetermined optimum value with respect to the flying direction of the floating body based on the analysis result. A magnetic bearing control device having a function.

In the magnetic bearing control device according to claim 2 ,
The magnetic bearing control device is provided with a loop cutting means for cutting the control loop, and the controller has a function of fixing a current flowing in the electromagnet of the magnetic bearing unit only to a bias current.

In the magnetic bearing control device according to any one of claims 1 to 3 ,
The controller includes a storage device that stores a bias current value adjusted via the constant current adjustment circuit, and uses the bias current value stored in the storage device for the floating control of the floating body. Magnetic bearing control device.