Comparative Analysis on Conducted CM EMI Emission of Motor Drives: WBG Versus Si Devices

TLDR

Silicon carbide and gallium nitride transistors are seen as future replacements for silicon devices in medium‑ and low‑voltage drives because of their low losses, yet their high‑speed switching is expected to worsen the already significant conducted common‑mode EMI of motor drives. This paper investigates and quantifies the increase in conducted CM EMI emission of a PWM inverter‑based motor drive when SiC and GaN devices are adopted. The study uses analytical modeling and laboratory tests to evaluate the impact of SiC and GaN devices on conducted CM EMI in a PWM inverter‑based motor drive. The analysis shows that dv/dt has a limited effect on conducted CM EMI, whereas switching frequency has a more significant impact.

Abstract

Silicon carbide (SiC) MOSFETs and gallium nitride (GaN) high-electron mobility transistors are perceived as future replacements for Si IGBTs and MOSFETs in medium- and low-voltage drives due to their low conduction and switching losses. However, it is widely believed that the already significant conducted common-mode (CM) electromagnetic interference (EMI) emission of motor drives will be further exacerbated by the high-speed switching operation of these new devices. Hence, this paper investigates and quantifies the increase in the conducted CM EMI emission of a pulse width modulation inverter-based motor drive when SiC and GaN devices are adopted. Through an analytical approach, the results reveal that the influence of dv/dt on the conducted CM emission is generally limited. On the other hand, the influence of switching frequency is more significant. Lab tests are also conducted to verify the analysis.