Variable Switching Frequency Modulation for Wide ZVS Range in Y-Inverter Using Adaptive Deadtime

Increasing the efficiency in buck-boost Y-voltage source inverter (Y-VSI) can happen by reducing the switching losses. This paper proposes a new soft-switching method to achieve minimum switching losses in Y-VSI. First, switching inductor current boundaries are found using the current equation in both buck and boost chopping operation. To minimize the required deadtime for capacitor discharging between turn on and turn off of the switches, an adaptive deadtime is calculated for both lower and upper boundaries of the inductor current. Using calculated deadtime for turn on and turn off in the switches, variable frequency pulse width modulation (PWM) signals are used to achieve full zero voltage switching (ZVS) range for both buck side and boost side switches in Y-VSI. Simulation results verify that the proposed ZVS method increases efficiency more than %2 in a 5 kW SJ-based Y-VSI.