Capacitance Optimization of Protective Snubber Capacitors in an Electric Power Converter

Abstract

This article considers an approach to capacitance optimization of snubber capacitors in power converters based on series connection of power semiconductor devices (PSDs) by selecting their parameters. Studies of PSD parameters in the state of high conductivity revealed their high scatter. This results in significant temperature variations of their semiconductor structures. To decrease overvoltage amplitude in devices and to optimize the parameters of protective snubber circuits, it is required to provide the closest thermal modes of operation of series PSDs. The thermal processes in PSDs were studied using an electrothermal model that is distinguished from those previously developed in Multisim environment in that the initial data are acquired during testing of devices. The experimental results demonstrated that, by selection of electric and thermal parameters, it is possible to decrease the capacitance of snubber capacitors by an order of magnitude. This will allow one to decrease significantly the loss in PSD semiconductor structures when toggling them from low to high conductivity and to minimize the weight and dimensions of gate units.