Research On Wide Speed Range Control Strategy Of IPMSM For Vehicles Based On Overmodulation

The control method of vehicles drive motor is the key influence affecting the performance of electric vehicles.Interior permanent magnet synchronous motor（IPMSM）has the characteristics of large output torque and high power density,and is one of the main types of electric vehicle driving motors.How to broaden the speed regulation range of this type of motor is a hot issue in the research field of motor control for vehicles.In this thesis,the flux-weakening control and overmodulation strategy of IPMSM for vehicles were studied.Firstly,the development status of flux-weakening control at home and abroad was studied,the flux-weakening control methods of past dynasties were listed.The advantages and disadvantages of each method and the improvement methods made by experts and scholars were analyzed,and their working principles and improvement measures were summarized.Then,the development status of overmodulation technology at home and abroad that could improve the utilization ratio of DC bus voltage was analyzed,and several methods of current overmodulation strategy were summarized.Secondly,in order to realize the overmodulation control technology of the interior permanent magnet synchronous motor for vehicles,an analytical model of this type of motor was established.Combining with the motor vector control method,the Maximum Torque per Ampere（MTPA）control method and flux-weakening control method were studied,and the application of overmodulation strategy in space vector pulse width modulation technology was also studied.Then,in order to solve the problems of current waveform distortion,torque and current curve fluctuation in the traditional negative d-axis current compensation method,the flux-weakening control strategy of negative d-axis current compensation method based on voltage difference feedback was studied.Through MATLAB/simulink simulation software,the characteristics of motor speed,current and torque under the proposed control method were verified.Finally,aiming at the problem that the traditional overmodulation strategy needs to calculate complex holding angle and reference angle,the simplified method of unified overmodulation strategy was studied.In view of the error of voltage correction in flux-weakening control,the overmodulation strategy based on voltage gain compensation was studied.Through MATLAB/simulink simulation software,the phase voltage,duty cycle and speed characteristics of the motor under the proposed control method were verified.