A hybrid PWM strategy based on SVPWM and SHEPWM for high-power drive system

In the high-power drive system such as traction drive system of rail transit, the hybrid PWM strategy is widely used due to the switching frequency limitation of the voltage source inverter. Since traditional multi-mode SVPWM strategy fails to reach the maximum of the utilization of DC bus voltage in low switching frequency at medium and high frequency band, this paper designs a hybrid PWM strategy based on SVPWM and SHEPWM for the high-power drive system. By eliminating the selective low-order current harmonics, the system can realize smooth transition to the six-step operation mode, hence reaching the maximum power output. Finally, case studies and harmonic analysis results prove the validity and practicability of the strategy.