Research On Torque Control Technology Of BLDCM For Pure Electric Vehicle

Nowadays,the global environmental problems are prominent.Excessive use of fossil fuels makes the energy crisis increasingly serious.With the advantages of zero emission,low noise and high energy efficiency,pure electric vehicles gradually occupy an increasingly important position in the automotive field.BLDCM is one of the main power sources of pure electric vehicle.Its motor control performance directly determines the driving and safety of the whole vehicle.Therefore,as the core technology of pure electric vehicle,motor torque control technology has become the hot spot of academic research.This dissertatinon takes the control system of the BLDCM of the pure electric vehicle as the research object,introduces the research status of the pure electric vehicle and the motor control system at home and abroad,studies the system structure and operation principle of the BLDCM,analyzes the cause of the torque ripple of the BLDCM,and studies the PID control principle of the BLDCM Based on the fuzzy control theory The fuzzy PI controller is designed.Aiming at the commutation failure of BLDCM in high speed mode,a coordinated control method is proposed to reduce commutation pulsation and commutation time.When the commutation angle is within the preset commutation angle range,the control strategy of reducing torque ripple is adopted.When the commutation angle is larger than the preset commutation angle,the control method of reducing commutation time is adopted to ensure the commutation success rate of the motor in the full speed range.At the same time,a simulation test model is built on MATLAB / Simulink software to test whether the designed fuzzy PI controller is reasonable and the proposed control strategy is effective.Based on the analysis of the basic functions and design requirements of the control system of BLDCM,the software and hardware of the system are designed with the idea of modularization.Hardware circuit design mainly includes: controller main circuit,inverter circuit,power circuit,protection circuit,phase current sampling circuit and position detection circuit.The software control flow design mainly includes: the main program of motor controller,capture interrupt subprogram,a / D correction program and the design of various interrupt subprograms.In order to verify the rationality of the motor control system designed in this dissertatinon and the effectiveness of the proposed control strategy,the test platform of the BLDCM control system is built,the hardware modules are debugged,and the proposed coordinated control method to reduce the commutation torque ripple and commutation time is verified by experiments.The experimental results show that the motor control system designed in this dissertatinon can operate reliably,and the control strategy can effectively reduce the torque ripple and improve the success rate of commutation.