A Four-level Active Gate Driver with Continuously Adjustable Intermediate Gate Voltages

The $dv/dt$ and $di/dt$ during switching transients are increased dramatically due to the very fast switching speed of silicon carbide (SiC) MOSFET, which are the major sources for the electromagnetic interference (EMI) noises. To improve the system's EMI performance, a novel four-level active gate driver (4-L AGD) with independent adjustable turn-on and turn-off gate voltages is proposed. Based on the trajectory modeling of the SiC MOSFET, $dv/dt, di/dt$, switch losses can be optimized by applying different intermediate voltage levels during turn-on and turn-off transients to improve the system EMI performance, suppress voltage and current overshoots and oscillations. Compared with the existing AGD with the fixed intermediate voltage, the proposed AGD's intermediate voltage level can be flexibly and continuously adjusted in a very wide range during both turn-on and turn-off transients. The proposed AGD working principles, trajectory modeling and the optimizations of the intermediate voltages are analyzed. Finally, simulations and experimental validations are carried out on a double pulse test platform with different intermediate voltages. The proposed AGD has the capability to fine tune $dv/dt, di/dt$ and suppress overshoots effectively according to the experimental results.