Research On Phase Voltage Compensation Strategy Of Pmsm For Electric Vehicle

Energy saving and environmental protection has become the theme of the 21 st century, for automobile industry, the Pure Electric Vehicle(PEV) is considered to be one of the most competitive developing direction in the new century. Driving system is the core component of PEV, and the motor combined with its control strategy is the key factors which determine the performance of PEV. With advantages of high power density, high efficiency and outstanding speed control performance, the Permanent Magnet Synchronous Motor(PMSM) is considered to be the most fitting motor for PEV. And Field Oriented Control(FOC) is widely used in PMSM driving system for its excellent speed and torque control performance. Currently, the battery voltage of PEV has been continuously increasing, upon with the nonideal characteristics of electron components, the distortion of phase voltage gets worse. To help improve the performance of PMSM driving system used in PEV, this thesis focuses on the FOC and phase voltage compensation.To analyze FOC, the structure of PMSM and the interaction between stator field and rotor field are introduced, then the flux-linkage equation, voltage equation and the torque equation are given under ABC coordinate system, ab coordinate system and dq coordinate system. Using the theory of energy converting between mechanical and electrical, quantitative analysis of electromagnetic torque is made. After simplifying the torque equation under dq coordinate system, the FOC model of PMSM is built.The causes and influencing factors of phase voltage distortion are analyzed, while the amplitude and the polarity of error voltage are given. Based on the results of error voltage, the compensation voltage is defined. By carefully derivation, the relation between compensation voltage and compensation time is found, while the equivalent current polarity is defined. In accordance with the derivation, both the the amplitude and the polarity of the compensation voltage can be deducted from the compensation time. According to the changing rule of compensation time, the measurement scheme of compensation time is designed based on the real-time feedback of phase voltage, and the complete strategy of phase voltage compensation is given.The simulation and experiments are carried out to validate the proposed phase voltage compensation method. The simulation is based on the Matlab Simulink module, and the experiment is conducted on the constructed test platform. Both of the simulation results and experiment results show the feasibility and effectivity of the proposed method, the error voltage is decreased and the waveform of phase voltage is improved.