A Study on Reduction Techniques of a Wideband Common-Mode Voltage Produced by a PWM Inverter

Switching speed of next-generation power devices such as silicon carbide is about ten times faster than those of silicon devices. This aspect may increase the frequency ranges of common-mode (CM) voltage accompanied by switching operations. Meanwhile, operating frequency ranges of noise filters typically limited by parasitic effects and frequency dependencies of magnetic components. Thus, it is difficult to suppress a wideband noise by installing only conventional passive noise filter. This paper studies about the combination of a conventional low-frequency passive filter and a high-frequency passive filter (HF-PF) which consists of a high-frequency magnetic material such as nickel-zinc ferrite. Furthermore, the proposed active CM voltage feedback circuit is applied for improving the performance of the HF-PF. An insertion effect against CM voltage produced by a pulse-width-modulated inverter is evaluated experimentally. Experimental results show that the constructed system effectively reduce CM voltage in the frequency range from 100 kHz to 100 MHz.