Comparative Performance Analysis of GaN FET and Silicon MOSFET in Closed-Loop Synchronous Buck Converter for Electric Vehicle Auxiliary Power Module

This paper presents a closed-loop synchronous buck converter based on Gallium Nitride (GaN) FETs and compares its performance with conventional Silicon (Si) based MOSFETs. Designed for a 60W power rating, this 48V/12V converter is integral to the Auxiliary Power Module (APM) in Electric Vehicles (EVs) to provide power to vehicle's 12V auxiliary loads and other electronic control modules. Hence, the design and operations of APM plays a significant role in enhancing vehicle performance, efficiency and drive range, while ensuring uninterrupted power supply to all auxiliary loads. The comparative analysis between GaN FETs and Si MOSFETs involves simulating the converter across a frequency range from 10 kHz to 5 MHz, with loss analysis conducted using PLECS thermal models of GaN FET and Si MOSFET, all controlled by a PID Type III voltage mode controller. Evaluation metrics includes controller performance, efficiency relative to switching frequencies, and power density in term of size of passive components.