Modeling of the High-Frequency Rectifier With 10-kV SiC JBS Diodes in High-Voltage Series Resonant Type DC–DC Converters

The superior material properties of the wide bandgap silicon carbide (SiC) semiconductors enable excellent device characteristics such as low on-resistance, high breakdown voltage, fast switching speed, high temperature operation, etc. 10-kV SiC junction barrier Schottky (JBS) diode prototype made by Cree was characterized in this paper first. The high-voltage (HV) and high-frequency rectifier consisting of SiC JBS diodes in dc-dc converters can potentially benefit from the device characteristics. However, capacitive current in both forward and reverse recovery process is observed due to the junction capacitance when the SiC JBS diode is turned on and off, which increases the reactive power and reduces the rectifier output power and voltage. To better utilize the devices, the rectifier operation is analyzed in consideration of the impact of the JBS diode parasitic capacitance. Two equivalent circuit models, the series and the parallel input impedance model, are proposed. The distributed junction capacitance of JBS diodes is lumped into the equivalent input capacitance such that the input impedance and output voltage, two critical parameters in HV dc-dc converter design, can be predicted from the models. Experiment setup of SiC JBS diode rectifier was built and the test results verified the modeling work.