A Transistor-Based Assist Gate Driver of SiC MOSFET for Crosstalk Suppression in a Phase-Leg Configuration

Abstract

Crosstalk in a phase-leg configuration significantly limits the high switching performance of silicon carbide (SiC) MOSFETs and results in additional switching loss, self-excited oscillation and even parasitic conduction. To give full play to the fast switching potential of SiC MOSFET, this paper proposes a negative voltage transistor-based assist gate driver (NVTAGD) to suppress the voltage spike caused by the communication. First, a simple circuit composed of capacitor, resistor and diode is applied to establish a negative gate-source voltage level. Then, two auxiliary transistors cooperate with capacitors and diodes to actively suppress the positive and negative gate-source voltage spike. The auxiliary transistor can flexibly adjust its working mode according to the operation states of the circuit without additional control signals. Finally, parameter design criteria of main components are also given to meet different operating conditions. A double-pulse experimental setup based on SCT3022AL SiC MOSFET is established to illustrate the effectiveness of the proposed method. The proposed NVTAGD generates a negative voltage of −2.3 V for the synchronous freewheeling device. And the positive and negative crosstalk voltage spike decreases by 52.6% and 44.9% respectively. Both positive and negative crosstalk voltages are limited by the safe range. A series of experimental results illustrate that the proposed method not only suppresses the crosstalk voltage but also increases the reliability of the devices.

Keywords

• Crosstalk suppression
• silicon carbide (SiC) MOSFET
• assist gate driver
• phase-leg configuration
• auxiliary transistors