Analysis of Influence of Frequency on Torque Ripple Based on High-Speed BLDC Drive System with SiC-MOSFET

In view of the large torque ripple of 1.2kW highspeed brushless DC motor during high-speed operation, the reason for the torque ripple generated by the motor is analyzed mathematically, as well as the relationship between PWM frequency and torque ripple. With Maxwell and Simplorer, a high-speed brushless DC motor control system is built. The current PI control and PWM-ON-PWM method is used. Not only are the motor current waveforms at different PWM frequency at the same speed compared and analyzed, but also the torque ripple is compared. Based on the SiC wide bandgap semiconductor device and the "China core" ---GD32F303 which is made by GigaDevice Company, an experiment platform is built. The 1.2kW high-speed brushless DC motor is driven. Simulation and experiments show that the improvement of the PWM frequency at the same speed can improve the current's quality, which can effectively eliminate torque ripple of motor. The suppression effect is remarkable at 10 kHz to 40 kHz, and it tends to be stable after 40 kHz.