Research On Driver And Control Strategy Of Permanent Magnet Synchronous Motor

With the advantages of simple structure,small moment of inertia and high efficiency,permanent magnet synchronous motor(PMSM)has taken a very significant place in the field of AC speed control system.Through coordinate transformation,the PMSM can be controlled like a DC motor by means of vector control method,thus excellent speed control performance is obtained.However,due to the nonlinear characteristics of the inverter and the distortion of air-gap magnetic field,the current of PMSM may contain a large number of high-order harmonic components.The harmonics could cause the distortion of current waveform and motor electromagnetic torque ripple,which limits the application of PMSM in high accuracy applications.In this paper,mathematical models of PMSM in different coordinate are analyzed and basic principle of vector control is introduced firstly,then the most commonly used control method called as id=0 current control is chosen and control block diagram is built to implement vector control of the PMSM.Aimed at the problem of electromagnetic torque ripple of PMSM,a control method in which harmonic compensating voltages are injected to suppress harmonic currents is adopted on the basis of the detailed analysis of the harmonic currents which is one of the main factors resulting in torque ripple.In this method,harmonic components in the motor current are extracted in real-time under harmonic dq synchronous rotating coordinate,then the closed-loop control of harmonic current is achieved by adding harmonic current loop.In the harmonic current loop,harmonic compensating voltages are obtained and then added to the modulation voltages to offset current harmonics in the motor.The motor current waveform is improved and finally the electromagnetic torque ripple is suppressed effectively.By means of MATLAB/Simulink,simulation models are built.A series of contrast simulations in which the harmonics suppression algorithm is added to the simulation model or not are implemented.The simulation results show that the current harmonics suppressing algorithm is feasible and it can decrease torque ripple of the PMSM effectively.Experimental platform of PMSM and its controller with TMS320F28069 as digital signal processor and resolver as the rotor position and motor speed sensor is built.By adding current harmonics suppressing algorithm or not,a series of contrast experiments are implemented on the experimental platform.The experimental results verify that the current harmonics suppressing algorithm is feasible and torque ripple reduction method is effective.