PCB Technology Comparison Enabling a 900V SiC MOSFET Half Bridge Design for Automotive Traction Inverters

The design of automotive traction inverters for an $800\ V$ dc-bus typically utilize $1.2 kV$ silicon carbide (SiC) metal oxide semiconductor field effect transistors (MOSFET). The $1.2 kV$ power devices allow for high overshoot voltages during switching transients but experience a high on-state resistance due to the die's thick drift layer region. This paper proposes the usage of $900\ V$ SiC MOSFETs for $800\ V$ automotive traction inverter applications. The proposed half-bridge design combines discrete power semiconductors and the dc-link capacitor on one printed circuit board (PCB). This design approach enables a small current commutation loop and thus a small overshoot voltage. Three different PCB technologies are compared based on their suitability for the traction inverter application. An $800\ V$ half-bridge prototype is designed, simulated, and tested. Measurement results are provided and show an overshoot voltage of $49.6\ V$ at a switching speed of $69 V/ns$ under maximum load conditions.