Self-controlled driver circuit optimizing dead time in fast GaN converters

Abstract:
GaN HEMTs are commonly operated in half-bridge-derived converters using their diode-like reverse conduction capability during dead time prior to ZVS turn-on. Application of an optimal dead time can significantly reduce reverse conduction losses but is strongly dependent on the load current IL and blocking voltage VDC. Within the load current range of 1 A ≤ IL ≤ 20 A and up to a DC-voltage of VDC = 400 V, this work presents a circuit for closed loop dead time control in a basic half-bridge converter which turns-on the transistor within 34 ns to 36 ns after reverse conduction has begun. Measurements and insight into the circuit design are provided. Currently relying on discrete components, the circuit provides an outlook on future integrated solutions, being especially feasible in lateral GaN HEMT technology.