Study On Flux Weakening Speed Regulation System Of Electric Vehicle PMSM

With the increasing consumption of fossil fuel resources and the impact of exhaust gases generated by traditional fuel vehicles on the ecological environment,traditional internal combustion engine vehicles have increasingly shown their limitations,and electric vehicles have received widespread attention in the field of automotive technology with their advantages of quiet and stable operation,high energy efficiency,low carbon and clean.Electric vehicles mainly use permanent magnet synchronous motors(PMSM)as the drive motor in China,which has the characteristics of simple structure,wide speed running range and large power density.In this thesis,PMSM is used as the research object,and the main analysis and research of the flux weakening control algorithm is used to enhance the operating capability of electric vehicles.Firstly,in view of the need for PMSM to advance the voltage utilization rate of the busbar and thereby advance the torque export capability,this thesis proposes a overmodulation strategy based on the advanced minimum amplitude error method,which is based on the spatial vector pulse width modulation(SVPWM)algorithm under the 120° coordinate system,which further expands the modulation area of the inverter from the linear modulation zone to the overmodulation zone.Compared with the traditional overmodulation algorithm based on the six-sector operation,the algorithm proposed in this thesis is based on logical judgment,which reduces the operation steps and saves memory resources,and can realize a smooth transition from the linear modulation zone through the overmodulation zone to the six-beat ladder wave mode.Finally,the fundamental amplitude and harmonic content of the overmodulated algorithm are compared and analyzed.Secondly,the export performance of the i_d=0 control algorithm and the maximum torque-to-current ratio(MTPA)control algorithm commonly used in the mainstream built-in permanent magnet synchronous motor(IPMSM)on electric vehicles is compared and analyzed in the base speed range.At the same time,the MTPA control strategy is combined in the highspeed stage,The flux weakening control strategy of voltage feedback in the forward angle is studied to expand the speed range of the motor.Aiming at the rapid attenuation of the export torque and the slow response of the forward angle under the flux weakening control conditions,the voltage utilization rate of the inverter is advanced by combining the overmodulation algorithm and the advanced angle judgment algorithm based on fuzzy control,respectively,so as to advance the torque export ability and advance the response speed of the forward angle judgment module.Finally,the hardware and software of the PMSM control system is designed.The hardware system adopts TMS32F28335 as the main control unit,and the main circuits include power drive circuit,resolver decoding circuit,detection and protection circuit,communication circuit and power supply circuit.The software part mainly includes the main program and the motor control main interrupt program,the former mainly completes the initialization configuration and cyclic execution of data transmission and other functions;the main interrupt program is the core of the entire control system program,mainly to achieve vector control including MTPA algorithm and weak magnet control algorithm,etc.After debugging and analysis,the effectiveness of the proposed algorithm is verified.