Power dissipation and thermal analysis of PMSM driver based on SIC MOSFETs

Silicon carbide (SiC) MOSFETs are becoming popular in Permanent Magnet Synchronous Motor (PMSM) driver designs. The power dissipation of MOSFETs is an important reference for evaluating the efficiency of PMSM drivers and implementing thermal design. This article performs power loss and thermal analysis of a three-phase, two-level PMSM driver based on SiC MOSFETs to evaluate the driver's efficiency and SiC MOSFETs' temperature under rated operating conditions. The transient switching process of SiC MOSFET is clarified in this paper, and the conduction and switching losses are calculated based on the MOSFET's parameters. The switching losses of the SiC MOSFET are calculated by analyzing the Miller plateau duration. Taking the conventional Space Vector Pulse Width Modulation (SVPWM) with the seven-segment switching sequence as an example, the average power dissipation is evaluated by calculating the conduction time of the SiC MOSFET within an electrical cycle. Based on the loss analysis, the temperature of SiC MOSFETs under air- and water- cooling conditions is analyzed using the finite element method. The effects of air volume and water flow on temperature are evaluated to aid in designing heat dissipation structures. A case study is conducted on one PMSM driver with 1kHz electrical frequency and 30kHz switching frequency.