Trade-Offs Between Radiated Emissions and Switching Losses in a SiC Module Under Different Active Gate Driving Strategies and Gate Resistances

A major challenge for engineers wanting to utilise SiC MOSFETs is the radiated emissions from their fast switching and oscillatory behaviour. The conventional solution to mitigate this is to increase gate resistance, however this significantly increases switching losses. Active gate drivers can be used instead to reduce overshoots and oscillations alongside their associated radiated emissions, while maintaining fast switching edges and low losses. This paper presents an empirical investigation comparing the use of increased gate resistance to different active gate driving strategies, quantifying the trade-off between radiated emissions and switching loss. Different active gate driving strategies are considered, targeting overshoot and post switching oscillation reductions to differing degrees. This study demonstrated that the reductions in emissions when active gate driving were localised to the frequencies associated with the oscillations and overshoot. However at these frequencies active gate driving can offer a better compromise between switching loss and emission reduction for both turn-on and turn-off compared to just increasing gate resistance. For turn-off all the strategies offered improvements, with damping just the oscillations giving the lowest energy loss while reducing the overshoots gave the best peak emission reductions. Due to excessive losses, the turn-on damped oscillation case had a significantly worse compromise than just increasing gate resistance, though the reduced overshoot cases offered marginally improved compromises.