MOSFET's Gate Resistance Influence on Voltage Imbalance of Two-Switch Flyback Converter

Abstract

proposed topic discuses design of auxiliary power supply, whose topology is based on the 2-switch flyback converter. The specifics of this solution is related to possibility of very wide input voltage supply (1-phase/3-phase AC or 120–650 Vdc) together with symmetrical outputs supplying auxiliary circuits of main power stage. The main outcome of paper is design proposal on main circuit of auxiliary supply (AUX) as well as on control and driving sub circuits. Control and driving parts have been analysed more in detail due to arise of voltage imbalance on power transistors during operation under high input voltage. This imbalance is caused by the topology itself because of different emitter potentials and thus dynamics that is related to Miller effect. Within this paper the solution how to overcome this deficiency is based on tuning the values of gate resistances on power MOSFETs. The procedure is verified by experimental testing. At the end, the performance of AUX is verified for full operation range.