| Rare-earth Rare earth permanent magnet brushless motor has been widely used in the field of industrial transmission because of its high energy density,wide speed range and simple structure.However,in the background of rising prices of rare earth,the production cost of motor has become a problem that can not be ignored.A Less-rare-earth spoke-type hybrid permanent magnet motor(HPMM)is studied in this paper,its excitation source using cheap ferrite non-rare-earth permanent magnet materials replacing part of NdFeB permanent magnetic materials,and through designing spoke-type rotor structure to compensate for the lack of electromagnetic performance which caused by the low coercivity of ferrite.Therefor,HPMM can obtain similar performance of rare earth permanent magnet brushless motor with reducing the use of rare earth materials which can reduce the cost of motor production too.But,mainly affected by combination of excitation mode,complex structure of the rotor and machining process of the motor,the air gap magnetic field of HPMM is distorted and,coupled with the inverter nonlinearity,inductance fluctuations and other factors,it will cause a lot of harmonics exsited in the winding phase current which can lead to temperature quickly rises and the efficiency significantly decreases when HPMM runs under traditional control.Therefore,in order to verify the actual performance of HPMM,and to achieve stable and efficient operation of it,the study will focus on HPMM control system,in addition,the analysis and suppression for harmonic current is also concerned in this paper.This paper first introduces the research background and structure of HPMM,and expatiates the working principle of HPMM.Then,designs HPMM control system based on the rotor field orientation control algorithm.The speed loop uses the compound PI controller,which can effectively solve the problem that traditional PI controller parameters are difficult to be adjusted;The current loop uses back-e.m.f PI controller to eliminate the influence of back-e.m.f on the system when speed changes,which can improve the performance of the control system.Finally,the performance of HPMM and its control system are verified by simulation and experiment respectively.For the phenomenon of phase current distortion in the actual operation of HPMM is obvious,the main causes of harmonic current are expounded from two aspects in this paper: the defective parameters of HPMM and the nonlinearity of inverter.And,according to the harmonic component of the actual phase current of HPMM,the mathematical model of harmonic current under d-q axis is established.Further more,the reason for PI controller can not completely eliminate d-q axis current disturbance is analyzed and verified.In order to eliminate the harmonic current,a method of current loop PI controller parallel resonant regulator is adopted in this paper.The method can form a proportional integral resonator in current loop which can eliminate the d-q axis current disturbance and achieve the unified suppression of three-phase harmonic current eventually.The validity of the harmonic current suppression algorithm is verified in simulation and experiment finally.The reasults of simulation and experimental show that HPMM can achieve desired dynamic performance under the control system designed in this paper,but the steady-state phase current is obviously distorted.Appling simple proportional integral resonator to the HPMM control system can effectively suppress the harmonic current of phase current and realize the stable and efficient operation of the motor.The control system designed by this paper can well reflect the performance of HPMM.The structure of proportion integral resonant controller is sample,the effect of it for harmonic current suppression is also obvious,and it only need realized in software without adding additional hardware circuit,Which provides a reference for the research on harmonic current suppression method of motor in the future. |
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