Partial Discharge Investigation of Medium Voltage PCBs for a 20-kV PWM Pulse Generator

As electric transportation systems advance towards medium voltage (MV) levels, ensuring partial discharge (PD)-free operation becomes increasingly critical. Printed circuit boards (PCBs), now extensively utilized in MV applications, require a comprehensive understanding of their PD characteristics to enable reliable and robust designs. This paper investigates the impact of different geometric configurations of PCB layout features on PD performance under ac and square wave voltages for MV PD-free PCB design. The findings can provide valuable insights for making better use of PCBs in compact MV power electronics for transportation electrification. Leveraging these insights, PD-free PCB designs for a 20-kV PWM pulse generator are proposed, incorporating a PCB-based dc busbar and a diode bank board. The design methodologies and analyses of these MV PCBs are presented in detail. Additionally, PD-free validation results for the proposed PCBs and the experimental performance of the PWM pulse generator are discussed. The developed MV PWM pulse generator, capable of achieving switching speeds higher than 100 V/ns, can serve as an essential evaluation tool for assessing PD-free operation for components in MV electric transportation systems.