A Case Study on Common Mode Electromagnetic Interference Characteristics of GaN HEMT and Si MOSFET Power Converters for EV/HEVs

Wide bandgap semiconductors, such as gallium nitride (GaN)-based power devices have become increasingly popular in the automotive industry due to their low on-state resistance and fast switching capabilities. These devices are sought to replace silicon (Si) devices in power electronics converters for vehicular applications. GaN devices dissipate less energy during each switching event, thus, GaN converter designers can significantly increase the switching frequency without increasing switching losses, relative to Si converters. However, one item of concern is that the high $dv/dt$ of GaN devices, due to the increased switching speed, has the potential to deteriorate the electromagnetic interference (EMI) emission of power converters, and thus may fail the corresponding regulations for vehicles. To understand these effects, this paper presents an experimental case study on the switching characteristics and common mode (CM) noise generation of a GaN-based half-bridge configuration operating in the synchronous boost mode. A comprehensive comparison has been made between the chosen GaN high electron mobility transistors (HEMTs) and Si MOSFET in terms of switching voltage waveforms, ground leakage currents, and CM noise spectrum. By parametrically increasing the gate resistance of GaN HEMT and Si MOSFET, the tradeoff between converter efficiency and CM noise generation is also quantified.