| Permanent magnet synchronous motor（PMSM）is widely applied in the area of industrial manufacturing,modern transportation and so on due to its several advantages like high power density and high efficiency.Especially in the field of new energy vehicles,the motor needs to be able to run in a wider speed range,so it is vital to adopt fluxweakening method to enlarge the speed range for PMSM under the condition that the motor structure and inverter capacity remain unchanged.PMSM works in constant torque mode below base speed,and in constant power mode above base speed.In constant power mode,the output voltage of the inverter reaches the maximum value,so the corresponding flux-weakening current needs to be applied to maintain the voltage balance when the speed expands.Finally,we can achieve flux-weakening control.Therefore,it is of great significance to study related technologies of PMSM magnetic weakening control to realize speed expansion.In this thesis,flux-weakening control method based on formula calculation method and torque feedforward flux-weakening control method are respectively used to carry out research.Firstly,this thesis introduces the mathematical model of PMSM and analyzes the basic principle and implementation method of SVPWM.On this basis,the principle and constraints of flux-weakening operation are analyzed.It provides theoretical foundation for the study of flux-weakening control technology.Secondly,the PMSM flux-weakening control system based on formula calculation method is constructed.The theoretical analysis shows that the given current of the system depends on the motor model and the accuracy of parameters.And the control performance of the system under traditional PI control is poor in magnetic weakening operation with the motor parameter perturbation and the accuracy of parameters.To solve this problem,the PMSM mathematical model considering parameter perturbation and unknown disturbance is built and a current loop control strategy based on adaptive uncertainty and disturbance estimator（UDE）is proposed,which improved the influence of parameter perturbation and external disturbance on system stability.At the same time,in order to get faster dynamic response and avoid the current fluctuation in the switchover process between maximum torque per ampere and flux-weakening control,the flux-weakening control strategy based on torque feedforward is constructed.On this basis,the complex vector current decoupling control based on disturbance observer is proposed.This strategy improve the cross-coupling effect of cross-axis current when PMSM is running at wide speed.Finally,the above flux-weakening control for PMSM are carried out on Simulink.And experiment and analysis of flux-weakening control for PMSM based on UDE is carried on d SPACE experimental platform.Simulation and experimental results verify the effectiveness of the proposed method. |
