Paralleling of Four 650V/60A GaN HEMTs for High Power Traction Drive Applications

This paper presents design considerations and experimental verification of a GaN-based half-bridge 650V/160A power converter block with four parallel 650V/60AGaN High Electron Mobility Transistors (HEMTs) for high-power traction drive applications. Paralleling of semiconductor devices is common for high power density applications. However, paralleling more than two GaN devices is challenging as parasitic inductances and resistances need to be well matched for all the devices. In addition, the DC loop inductances must be minimized to reduce the device voltage overshoot during turn-off. The gate loop inductances must also be matched and minimized to improve current sharing and reduce gate voltage oscillations. A detailed design method of a half-bridge with four parallel devices is discussed in this paper for matching gate and DC loop inductances. A half-bridge test circuit with four parallel enhancement-mode GaN (e-GaN) HEMTs is designed following the design method. The inductance matchings are verified with a detailed Q3D simulation. Finally, Double Pulse Test (DPT) results at 400V/160A are presented in this paper to demonstrate the half-bridge converter block’s current sharing and loss distributions.