Current Harmonic Suppression In The Flux-weakening Control Of Surface Permanent Magnet Synchronous Motors

With the advantage of reliable operation and high power density, surface mountedpermanent magnet synchronous motor is widely used in electric vehicles, aerospaceand other fields. As the magnetic field generated by the permanent magnet cannot beadjusted,, the motor back EMF will reach the inverter output voltage limit as themotor speed increases. Therefore, the motor speed cannot continue to rise, which willlimit its application in the field which has wide speed range, constant power operatingrequirements. Overmodulation strategy and field-weakening control can expandPMSM speed range, but introduce current harmonics motor control systems, andproduce torque ripple. Therefore, this paper analyzed the reasons for the modulationcurrent harmonics and proposed current harmonic suppression strategy.To solve the problem of harmonic current and torque ripples caused byovermodulation strategy, a proportional–integral–resonant control strategy and adeadbeat control strategy are proposed in this paper. Starting from the model ofPMSM, based on the principles of field weakening control strategy andovermodulation strategy, this paper analyzes the reasons of current harmonics,researchs the inhibition of disturbance signals by the current controller gain, buildsPIR current controller, derives the controller parameter. The proposed mothod cansuppress the current harmonics of field-weakening conditions, improve the systemsteady-state operation capacity. To further improve the dynamic performance of thesystem, the deadbeat control strategy of current loop is proposed. This paper analyzesthe steady-state error caused by deadbeat control strategy in the condition of modelparameters mismatch, and uses a low-pass filter to eliminate the steady-state error,compares the stability of before and after compensation control system. Finally, twooptions are provided to solve the current sampling delay problems. Resarchs haveshown that deadbeat current harmonic suppression strategy can effectively suppressharmonic and improve static and dynamic performance of the system.On the basis of permanent magnet synchronous motor control system simulationand experiment platform, the PIR current harmonic suppression strategies anddeadbeat current harmonic suppression strategy are simulated, and the PIR current harmonic suppression strategy is experimentally verified. The results show that boththe proposed harmonic current suppression strategies can effectively suppressharmonic current generated by the overmodulation and reduce the torque fluctuations.