Research On Current Control Strategy Of Interior Permanent Magnet Synchronous Motor

China has been the largest country of automobile production and consumption.Automobile exhaust's pollution to the atmospheric environment has become more and more serious,so new energy vehicles are considered the alternative solution of traditional vehicles.The electric drive system of new energy vehicles generally uses the interior permanent magnet synchronous motor as the core power.This paper mainly revolves around an interior permanent magnet synchronous motor(IPMSM).According to IPMSM structure and operation principle,the mathematical models of motor in static coordinate and in rotary two-phase coordinate under the principle of coordinate transformation are presented.Based on that,the mathematical model of AC motors using complex vectors is developed.It can make the original motor system become SISO system in which the current loop can be analyzed in classical control theory.It is concluded that the traditional PI current regulator performs even worse when the speed goes up.The “relative gain” is introduced to analyze the coupling phenomena of PMSM current loop firstly.Three different decoupling control schemes are elaborated in the paper,such as internal model decoupling control,feed-forward compensation decoupling control and diagonal compensation decoupling control.Schemes can be tested using complex vectors or be verified from the perspective of multivariable control system.Simulation and experimental results both show that three decoupling control schemes can reduce the coupling phenomena effectively so that they are able to improve the precision of controlling torque.The parameter robustness of three control schemes is simulated when only one factor is different at a time.The simulation result shows that diagonal compensation decoupling control has the best parameter robustness among the decoupling schemes.Maximum torque per ampere(MTPA)control strategy is studied in this paper when the IPMSM is under the base speed.It can improve the torque output compared to the id=0 control strategy.By increasing the demagnetization current or using the single current regulator control strategy based on the coupling phenomena,the motor can run in the flux-weakening region.Finally simulation and experimental results show that,the control strategies in this paper can effectively use the DC bus,improve the efficiency and output torque at low speed,and broaden the speed range.