Electrothermal Design of a Discrete GaN-Based Converter for Integrated Modular Motor Drives

Integrated modular motor drives (IMMDs) have a compact and high fault-tolerant structure compared to their conventional counterparts. The most challenging issue in the implementation of these drives is the thermal management of the inverter modules due to the small space available for each module and its physical proximity to the machine windings with their high heat production. The electrothermal design of a discrete half-bridge inverter module for a radially stator-mounted (RSM) axial flux integrated drive is introduced in this article. The inverter modules are mounted on the stator, radially along the circumference. The converter is implemented using GaN technology, and the size is optimized. The structure of the presented integration topology from the case of the switches to the cooling ambient is optimized from the thermal point of view. The converter is modeled using steady-state and transient lumped parameter thermal networks to estimate the steady state and the instantaneous temperature of the switches. The converter parasitics are extracted using FEM simulations, and their influence on the switch loss and temperature is evaluated. The lumped parameter modeling is validated with computational fluid dynamics (CFD) simulations and experimental measurements.