Modeling of the impact of diode junction capacitance on high voltage high frequency rectifiers based on 10kV SiC JBS diodes

There is strong industrial need to boost the power density of the high voltage generators, for example, in medical radiology applications. 10kV SiC JBS diode is potential candidate to be employed in the high voltage high frequency rectifier in future high voltage generator applications. However, the impact of the relatively large diode junction capacitance of SiC JBS diode cannot be neglected at high frequency and high voltage conditions. An electric circuit model is proposed to describe this effect for full bridge and half bridge high voltage diode rectifiers based on mathematical derivations. The effect of junction capacitance is to decrease the output voltage and to increase the ratio of capacitive reactive power in the circuit, which can be represented by an equivalent shunt capacitor with input source and ideal diode rectifier. The model is validated by simulation results, and can be used for the further design of the high voltage generators.