Advanced PWM Techniques for Multi-Level Inverters With a Multi-Level Active CM Noise Filter

Pulsewidth modulation (PWM)-based power electronics inverters are being widely used for various applications, including motor drives. However, the common-mode voltage (CMV) resulting from switching operations in the PWM inverters causes significant performance degradation of the system and can cause potential damage to motors. Since the effects of the CMV can be more severe in wide bandgap (WBG) and high switching frequency-based converter systems, various methods have been proposed to mitigate the CM noise issues. This work presents a multi-level inverter system composed of a multi-level inverter with a proposed multi-level active power filter (APF). For attenuating the CMV in multi-level inverters using multi-carrier-based PWM methods, a novel PWM method is presented for the proposed multi-level APF. The three-phase five-level active-neutral-point-clamped (ANPC) II-type inverter using the apparent switching frequency doubling (ASFD) PWM is used as an example of the multi-level inverters and carrier-based PWM methods to analyze and verify the proposed CMV attenuation method. The APF generates and injects the APF voltage equal to the CMV to attenuate the CM noise accurately. Various key challenges, including the dead-time compensation, are addressed through the proposed advanced PWM techniques to improve the CMV attenuation performance. Simulation and experimental results are provided to verify the comparison and effectiveness of the proposed CMV attenuation method.