An Optimized Reverse Recovery Model of Trench Gate Power Si MOSFET Body Diode

The trench gate power Si MOSFETs (U-MOSFETs) hold significant advantages over wide-bandgap (WBG) devices in low-voltage and low-frequency applications due to their high current density, low on-state resistance, cost-effectiveness, and reliability. However, in the inverter half-bridge, the reverse recovery characteristics of U-MOSFET body diodes (BD) and the nonlinearity of junction capacitances affect the drain-source current and voltage trajectories during the reverse recovery stage (RRS), resulting in high di/dt variation and loss. The accuracy of current and voltage trajectories in the RRS is crucial for evaluating U-MOSFETs' turn-on transient. Nevertheless, the current and voltage trajectories in RRS described by the SPICE model diverge from actual results due to insufficient attention to the nonlinearity characteristics of junction capacitance. To address the aforementioned problem, a method is presented using the capacitance-voltage (C-V) characteristics of the junction capacitor C_oss to describe the transient voltage drop of BD in the RRS. Subsequently, the current-voltage time relationship of BD in RRS is derived. Finally, an optimized reverse recovery model of U-MOSFET is proposed. Experimental results show that the proposed model has the ability to accurately model the current and voltage trajectories of U-MOSFETs in RRS. The relative errors of di/dt variation and loss of the proposed model are reduced by at least 49.7% and 73.8% compared to the SPICE model, respectively.