A Fiber-Optic-Less 50-MHz Single Transformer Isolated Gate Driver With Fault Feedback for 10-kV SiC MOSFETs

This article presents a novel fiber-optic-less 50-MHz single transformer isolated gate driver (GD) for medium voltage (MV) SiC
mosfet
s. A unique edge-interval-OFF modulation scheme is proposed to allow signal and power simultaneously transmitted through a single transformer with minimal power switches and voltage sources. The proposed GD can also transmit the fault signal from the GD secondary side to primary side, eliminating the requirement for fiber-optic (FO) communication for fault feedback. The proposed GD offers a low propagation delay and can respond to short pulsewidths, as well as supports an ultra-wide duty-cycle range including 0% and 100% duty-cycle operation. Furthermore, it utilizes solid dielectrics to achieve a compact footprint of 61 mm × 24 mm × 30 mm and meet MV insulation requirements with a partial discharge (PD) inception voltage > 13.5 kV
_RMS
under 60-Hz ac voltage and a PD-free operation under 100-kHz, 5-kV PWM voltage with a
dv/dt
of 100 V/ns. The proposed GD achieves an ultra-low coupling capacitance of 1.9 pF and a common-mode transient immunity (CMTI) > 100 V/ns, making it preferable to drive MV SiC
mosfet
s with high
dv/dt
. The proposed GD eliminates the need for both FOs and bulky GD power supplies, resulting in a more than 10-fold reduction in size compared to conventional 10-kV isolated GDs and has the potential to be integrated into MV SiC device packages. Experimental results on 10-kV SiC
mosfet
s validate the effectiveness of the proposed GD.