Design Of Permanent Magnet Synchronous Motor Control System Based On Silicon Carbide Devices

The emerging silicon carbide power devices have the characteristics of fast switching speed,high blocking voltage and high temperature resistance.When they are applied to the control system of permanent magnet synchronous motor,they can meet the requirements of high efficiency,high power density and high reliability in the fields of electric vehicles,aviation and aerospace.In this article,SiC power devices are applied to the motor driver to improve the efficiency and power density of the system,and the bridge arm crosstalk problem is solved by negative pressure turn off combined with external capacitance.In order to improve the dynamic performance.of the system,the double closed-loop vector control technology and the fuzzy control idea are used to design the fuzzy PI speed controller and the traditional PI current controller.The specific research work is as follows.Firstly,the composition of motor inverter loss is analyzed,and the calculation formulas of on-state loss and switching loss of power devices are derived.Comparing the device losses of SiC MOSFET and Si IGBT under the same working conditions,the experimental results show that the SiC device can reduce the inverter losses and improve the efficiency of motor driver.On this basis,the problem of bridge arm crosstalk in the motor driver is deeply analyzed,the solution of negative pressure turn off combined with external capacitance is proposed,and the suppression effect is given.Aiming at the problem of motor dead time effect,SiC high-speed switch is used to reduce the dead time,so as to reduce the motor dead time effect.The experimental results show that the system has low current harmonic content and small torque ripple,which can reduce the dead time effect.Secondly,this paper briefly introduces the structure of permanent magnet synchronous motor,elaborates the principle of coordinate transformation,gives the mathematical model of permanent magnet synchronous motor after coordinate transformation,and states the principle of voltage vector control on this basis.Based on the high-speed and high-precision performance requirements of silicon carbide motor control system,on the basis of traditional double closed-loop vector control,fuzzy PI controller is applied to speed loop control,and fuzzy PI speed controller and traditional PI current controller are designed.Two kinds of control systems are simulated under three working conditions of no-load operation,speed mutation and constant speed loading.The results show that the system with fuzzy PI speed controller has better dynamic performance.Finally,a Permanent Magnet Synchronous Motor(PMSM)control system based on the TMS320F28335 microcontroller is designed,and a speed regulation experiment is carried out on the designed PMSM control system.The experimental results show that the dead time is up to 0.5μs,at the same time,it can effectively suppress the crosstalk problem of the bridge arm;it runs stably under the condition of the switching frequency of 40kHz,the speed range is wide,the current waveform is similar to a sine wave,and the motor rotates smoothly.