Impact of Gate Resistance on Miller Effect to Prevent MOSFETs Shoot-through Phenomena in Inverter Application

Traction Inverter plays a crucial role to operate the electric vehicle with desired torque and speed curve based on the commutation of MOSFET. Safe operation of traction Inverter is necessary to drive the motor for intended operation. Gate drive on the signal level is used to amplify the input signal from microcontroller to source and sink gate currents based on required level of MOSFET switching time. Throughout the MOSFETs switching process, there's a risk of positive voltage surge between the gate and source terminals. Gate resistors in the gate path play a critical role in gate driver or totem pole circuits by exerting control over the flow of current, thereby ensuring the stability and reliability of the system. The miller capacitance referred as drain to gate capacitance causes the positive voltage spike at gate to source terminals of the MOSFET during its PWM shutoff condition, influences the safe operation with shoot through scenario. The focus of this paper lies in presenting a method aimed at mitigating the occurrence of positive voltage spikes between the gate and source terminals of MOSFET by increasing the on-time gate resistance without significantly impacting switching losses and temperature rise of the MOSFET. Thorough theoretical analysis and experimental validation are presented for the effectiveness of the proposed method demonstrated in this paper.