Effects of Nonlinear Junction Capacitance of Rectifiers on Performance of High Voltage Power Supplies

Silicon carbide diodes are commonly used in high voltage (HV) power supply rectifiers due to their ability to operate at high frequencies and compact size. This article presents a thorough analysis of how the diode's junction capacitance affects the performance of an HV power supply that includes an
LCL
/P resonant network-based converter and a voltage multiplier. By taking into account the voltage change across the diode due to resonance and voltage buildup, the equivalent junction capacitance of the diode is derived using charge equivalence, which leads to an equivalent circuit of the converter. The analysis shows that the diode's junction capacitance can result in multiple operating points, which can affect the HV power supply's voltage gain and controllability. To ensure a unique operating point and meet design specifications, a parameter design method is proposed. The proposed method is validated through simulation and experimental results from a prototype with a 21–35 V input/3.4–4.4 kV output operating at 450 kHz.