Effects of Internal Feedback and Gate-Drive Signal on the Turn-off Loss of MOSFET ZVS

This paper studies the effects of internal feedback through device's parasitic capacitances and inductances associated with gate-drive signal on the turn-off loss of MOSFET operates as zero-voltage switch in Class-D resonant inverter. Expressions relating parameters of Miller feedback and gate-drive circuit to Miller voltage were derived. Impeding turn-off and re-turn-on of conduction channel are responsible for higher turn-off loss. Switching trajectory, energy transferred into the MOSFET in each switching cycle, as well as turn-off loss for different gate- drive signal were calculated using data obtained from computer simulations. The results are compared with those calculated from experimental data. Voltage dependent parasitic capacitances of the MOSFET were estimated from experimental data and used for the calculation channel current.