基于磁耦合闭环控制的GaN HEMT有源栅极驱动器以抑制关断时漏源电压过冲及电磁干扰

Compared with traditional Si mosfets, gallium nitride high electron mobility transistors (GaN HEMTs) have faster switching speeds. During the turn-off process of GaN HEMTs, the rapid decline of current causes serious drain-source voltage overshoot and electromagnetic interference, which limits the reliability and application scenarios. This article proposed a GaN HEMT active gate driver based on magnetic coupling closed-loop control (MCCLC) to address these issues. In MCCLC, coils arranged near the power loop can accurately provide di/dt feedback of the power side under completely electrically isolated conditions, which is more reliable than traditional methods. The proposed method does not require additional control signals and can segmentally optimize the gate drive voltage during turn-off transients. A double-pulse test (DPT) based on the GS66508B verifies the effectiveness of MCCLC at 400 V/30 A. Compared with CGD (conventional gate driver), the overshoot of the drain-source voltage decreased by 51.8%, the average slope of current decline was reduced by 24.2%, and the high-frequency component of the drain current at approximately 80 MHz was reduced by 11.2 dBμA. MCCLC has a 36.9% lower turn-off loss than CGD with a larger gate drive resistor when they have almost the same voltage overshoot.