D2.2. Active gate drivers for high-power, highfrequency WBG devices

Active gate driving has been shown to provide reduced circuit losses and improved switching waveform quality in power electronic circuits. Featuring higher switching speed and lower losses, the silicon carbide MOSFETs and GaN devices are widely used in higher power density and higher efficiency power electronic applications as a new solution. However, the increase of the switching speed induces oscillations, overshoots, electromagnetic interference (EMI) and even additional losses. High – voltage, high – power T-Type RHODaS SiC/GaN inverter uses power devices working at 1000VDC in DC bus, while intermediate GaN leg has to support 500VDC as a rated voltage. Reducing voltage and current overshoots becomes crucial to allow the use of 650V GaN, which represent the current available technology. This deliverable studies, develops and tests a novel active gate driver (AGD) for highpower GaN switches, that allows to fully using its potential of high-speed characteristic under different operation temperatures and load currents. The principle of the AGD is based on drive voltage decrement during the voltage and current slopes since high dV/dt and dI/dt are the source of the overshoots, oscillations and EMI problems. This voltage control is achieved by a duty-adjustable high frequency pulse train generated by a FPGA that modifies the input and output sides of the PWM pulses applied to the gate of the transistor, thus generating a variable drive voltage that change according the switching conditions. Compared to conventional gate driver (CGD) with fixed drive voltage, the proposed AGD has the capability of suppressing the overshoots, oscillations and reducing losses without compromising the EMI. Analytical developments, simulations and experimental results are showed in the deliverable, which are the basis for the future utilization of these advanced gated drivers in RHODaS power converters.