Efficiency enhancement of a three phase Soft Switching Inverter under light load conditions

This paper studies the performance of a three phase Soft Switching Inverter (SSI) under extremely light load conditions (7W, 150 mA-peak, 50 V-peak which is 10% of its thermally maximum permissible power). An Auxiliary Resonant Commutated Pole Inverter (ARCPI) has been selected as soft switching topology for this research. Analytic approaches are used to compute the losses and to select the power transistor which best fits this application. Two options to enhance the efficiency are discussed. First, the switching losses of the auxiliary switches are reduced by optimizing the turn on and off sequence. Second, a Resonant Gate Drive (RGD) is employed to reduce the gate losses of the switches. A single phase prototype has been realized. Measurements and computed losses are compared to validate the model and the calculations.