Research On Flux-weakening Control Strategy Of PMSM For Electric Vehicles

The permanent magnet synchronous motor(PMSM)is widely used in hybrid electrical vehicle and blade electric vehicle due to its small size and weight,high power density and efficiency,etc.In addition,the permanent magnet synchronous motor also has excellent fluxweakening(FW)performance.This paper focus on flux-weakening control system.First,the traditional voltage feedback control is analyzed to expand the motor speed region and it is found that the dynamic performance of high-speed area is greatly affected by the current coupling.Aiming at the shortcomings of this algorithm,this paper adds voltage phase angle control on the basis of traditional single current regulator(SCR)strategy,and these two methods are verified and compared through simulations and experiments.The brief content of the full paper is as follows:1.Considering the PMSM model in the rotating coordinate system,the theoretical trajectory and operating boundary of PMSM in the flux-weakening region are given,and the trajectory is verified in this paper.2.This paper adopt the traditional voltage feedback control to realize automatic fluxweakening.It is found that this method has the defects of poor anti-interference ability in the high-speed region and serious coupling between the d axes and q axes.In response to these problems,the traditional SCR can effectively use the d and q axis current coupling relationship to achieve the purpose of FW in high-speed region.However,this method has poor DC voltage utilization and loading capacity.Therefore,this paper adds voltage phase angle control on the basis of the traditional SCR.It is proved that the control strategy has high parameter robustness,high voltage utilization rate and good loading capacity.Besides,it can also effectively reduce the motor loss.3.The software and hardware design of PMSM controller for electric vehicles are completed.The voltage feedback control and the SCR method with voltage phase angle control are realized through this controller.The results show that the field weakening method with voltage phase angle control can expand the speed region automatically and has higher voltage utilization rate and lower motor loss.