Model Design for Evaluating Oscillating Voltage Characteristic in Hybrid-Switch T-Type Converter Considering Parasitics

High frequency and high voltage switching converters utilizing Wide Bandgap Switches (WBG) are gaining popularity thanks to their compactness and improved efficiency. However, the faster switching requirements gives rise to new challenges. In particular, the key issue is the increased oscillation of the drain-source voltage, which may damage the switch with limited voltage blocking range. This is mainly because of the parasitic inductances of the layout and intrinsic capacitances of the switch. This paper introduces an analytical methodology for analyzing this issue in T-Type converter. A transient model of the converter is developed, in which all the relevant parasitic capacitances and inductances are taken into account. The dependency of drain-source voltage oscillation's magnitude and the natural frequency of this oscillation on the parasitic capacitances and inductances are investigated theoretically. Applying double pulse test (DPT) method to the built T-Type converter, the proposed analytical model is qualitatively verified by experimental results.