Active dv/dt Control of 600 V GaN Transistors
The paper proposes a new active dv/dt control circuit with a fast response to change the 600 V GaN HEMT turn-off and turn-on dv/dt slew rate freely and independently while the converter is running. The proposed circuits are shown in Fig. 1. Simulations are first performed to verify the circuit function while considering all the possible parasitics distributed on the experimental setup, and a detailed circuit design follows. The hardware is illustrated in Fig. 2. Experimental results, shown in Fig. 2, obtained on the 300 V dc 15 A load current double pulse tester, composed by a GaN HEMT phase leg, validates the proposed method by varying turn-on dv/dt slew rate from 27.1 V/ns to 8.8 V/ns turn-off dv/dt from 34.6 V/ns to 7.6 V/ns. Finally, a comparison with different gate resistors is provided, showing the proposed method has a smaller switching loss under the same dv/dt condition rather than using a large gate resistor.