Improved Performance of Modular Multilevel Converter for Induction Motor Drive

Multilevel converters provide an attractive solution to bring the benefits of speed-controlled rotational movement to high-power application. The Modular Multilevel Converter (MMC) is an improved multilevel converter topology preferred for high power applications in recent years. This paper presents an approach to improve performance of MMC for control of Induction Motor (IM) Drive. Experimental results of three phase MMC controlling ac drive are presented. Switching pulses are generated using Digital Signal Processing DSP TMS320F2812. Performance evaluation of MMC is measured through Weighted Total Harmonic Distortion (WTHD). Simulated results of both Sinusoidal Pulse Width Modulation technique (SPWM) and Selective Harmonic Elimination Pulse Width Modulation (SHE-PWM) technique are compared. FFT analysis shows that lower order harmonics can be eliminated with less switching frequency using SHE-PWM. Result shows that WTHD for line current and line voltage reduces using SHE-PWM technique as compared to SPWM technique for same switching frequency, which will be helpful in reducing the losses and improving motor efficiency.