Electricity: motive power systems – Induction motor systems – Primary circuit control
Patent
1999-07-14
2000-06-27
Ip, Paul
Electricity: motive power systems
Induction motor systems
Primary circuit control
318809, 318811, 318801, H02P 528, H02K 1742
Patent
active
060810939
DESCRIPTION:
BRIEF SUMMARY
FIELD OF ART
The present invention relates to a sensorless control method and apparatus of a permanent magnet synchronous motor which does not have a position detector and a speed detector.
BACKGROUND ART
When a brushless DC motor using a permanent magnet as a rotor is driven as a synchronous motor, it is necessary that the absolute position of the rotor is obtained and the correct current control is performed. In order to obtain the absolute value of the rotor, a rotor position detector such as an encoder or a resolver is generally used. However, since there are problems regarding complicateness of wiring or structure, price, use environment and the like, methods of estimating the position of the magnetic pole not using a rotor position detector have been proposed.
In the prior art, methods of estimating the position of the magnetic pole of the permanent magnet synchronous motor are known as follows.
[1] The Transaction of the Institute of Electrical Engineers of Japan, Vol. 113-D, No. 5, May 1993, p579 to 586.
[2] The Transaction of the Institute of Electrical Engineers of Japan, Vol. 114-D, No. 5, May, 1994, p591 to 592.
[3] The Transaction of the Institute of Electrical Engineers of Japan, Vol. 115-D, No. 4, April, 1995, p420 to 427.
[1] is a method that when stator currents I.sub..alpha., I.sub..beta. converted to .alpha.-.beta. axis coordinate system set on the stator are made observed values and stator voltages v.sub..alpha., v.sub..beta. are made inputs, magnetic flux .lambda..sub..alpha., .lambda..sub..beta. and rotor speed are estimated using adaptive rule.
[2] is a method that when stator currents i.sub..alpha., i.sub..beta. converted to .alpha.-.beta. axis coordinate system are made observed values and stator voltages v.sub..alpha., v.sub..beta. are made inputs, induced voltage .epsilon..sub..alpha. generated in the .alpha. axis direction in the .alpha.-.beta. axis coordinate system and induced voltage .epsilon..sub..beta. generated in the .beta. axis direction are estimated as disturbance.
[3] is a method that deviation angle .theta.e between the .gamma.-.delta. axis and the d-q axis is estimated from difference between stator currents i.sub..gamma., i.sub..delta. converted to the .gamma.-.delta. axis coordinate system set on the stator and rotating in the synchronous speed and current calculated values i.sub..gamma..spsb.0, i.sub..delta..spsb.0 calculated from model.
However, problems in the above-mentioned conventional methods are as follows.
Regarding [1], when the method is adopted in a permanent magnet synchronous motor having polarity, on the .alpha.-.beta. axis coordinates, the inductance becomes function of the rotor angle .theta.r of the motor and the state equation becomes complicated, and when an observer is to be constituted, the calculation amount is increased and the utilization is difficult. Also since the flux .lambda..sub..alpha., .lambda..sub..beta. is made unknown quantity, the state equation becomes non-observable at the rotor speed being zero and the estimator itself becomes unstable.
Regarding [2], since the induced voltage converted to the .alpha.-.beta. axis becomes alternating quantity, if the pole of the observer is not set large, the phase difference is produced between the actual quantity and the estimated quantity and the method becomes not to be used.
[3] is a simple method in comparison with [1], [2], moreover since the .gamma.-.delta. axis rotating at the angular velocity substantially synchronized with the d-q axis is considered as the reference, when the deviation .theta.e between the d-q axis and the .gamma.-.delta. axis is small, the state equation is not complicated and the method is excellent regarding the utilization. However, since the actual value is compared with the calculated value simply introduced from the model when the .gamma.-.delta. axis is coincident with the d-q axis, the deviation .theta.e can not be always estimated correctly due to the modeling error.
Further in the reference of [3], a method is taken in that the speed estimated value
REFERENCES:
patent: 5038092 (1991-08-01), Asano et al.
patent: 5182508 (1993-01-01), Schauder
patent: 5565752 (1996-10-01), Jansen et al.
patent: 5585709 (1996-12-01), Jansen et al.
patent: 6002234 (1999-12-01), Ohm et al.
Fujii Shuichi
Inazumi Masanobu
Oguro Ryuichi
Ip Paul
Kabushiki Kaisha Yaskawa Denki
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