Research On Dead-Time Compensation Method Of PMSM For Fitness Vehicle

Permanent magnet synchronous motors have attracted more and more attention due to their advantages such as simple structure,low operating loss,high torque control accuracy,and easy maintenance.At the same time,the integration and miniaturization of power electronic devices and the rapid development of microcontroller processing performance make it widely used in small and medium power applications.This paper takes "Research on High Performance Resistance Control Strategy of New Fitness Vehicle" as the background.Based on the analysis of traditional fitness vehicle's resistance adjusting mechanism,this paper proposes to implement the high-precision torque control the permanent magnet synchronous motor(PMSM)under vector control.Focusing on the problems of torque ripple,current harmonic and zero current clamp caused by dead-time effect of inverter under SVPWM modulation,the mechanism and compensation method of dead-time effect of PMSM are studied deeply.This article first describes the structure layout of PMSM,establishes a mathematical model under different reference systems.The expressions for the effects of disturbances such as dead time,inverter switching frequency,DC supply voltage and power factor are derived,and the above effects are simulated and verified in the MATLAB/Simulink.The conventional dead-time compensation method can only perform fixed offset voltage compensation.In view of this shortcoming,this paper proposes two improved compensation methods,the two methods are the current feedback dead-time compensation based on fuzzy control and the on-line dead-time compensation based on disturbance observer.The on-line dead-time compensation based on disturbance observer establishes a nominal model of the system based on motor parameters.The dead-time,turn-on and turn-off delays of power devices,saturation on-voltage drop and deviation voltage caused by the fluctuation of the bus voltage are observed and compensated by feedforward as the disturbance voltage.Aiming at the fuzziness of current detection caused by zero current clamp phenomenon,the current feedback dead zone compensation based on fuzzy control determines the current direction according to the current and current slope near the zero crossing point,and reduces the repeated zero crossing to improve the compensation accuracy.The phase current harmonic rate and torque fluctuation are selected as the main control performance indicators.Simulation experiments of three different dead-band compensation methods are completed in MATLAB / Simulink.The simulation results verify the effectiveness and superiority of the proposed dead-time compensation method.Finally,the hardware structure of PMSM control system based on STM32F103 is developed,and the related software design is completed.The vector control without dead time compensation based on id=0 and the dead time compensation control based on disturbance observer are realized.The comparison and analysis of the two experimental results show that the compensation method proposed in this paper can effectively weaken the adverse effects caused by the dead zone effect.