Study of Partial Discharge Inception Characteristics of Aviation Wire Stressed by PWM Voltages Under Various Air Pressures

Partial discharge (PD) is a common and detrimental phenomenon that can cause damage and potential breakdown in insulation systems. According to the air breakdown voltage behaviors shown by Paschen's curve, from sea level to high altitude, the partial discharge inception voltage (PDIV) of the air is expected to decrease with decreasing pressure. So far, there has not been a widely accepted PD testing method for aviation wires in low pressure environments with pulse width modulated (PWM) voltage excitations. There have been studies of the PD behaviors of aviation wires with conventional triangular impulses, ac voltages, and PWM pulses with relatively low
$\text{dv}/\text{dt}$
. But existing test methods and study results cannot be directly utilized to test and predict PDIV of aviation wires when high
$\text{dv}/\text{dt}$
PWM excitation is applied with wide-bandgap (WBG) power devices, such as Silicon Carbide (SiC) Metal Oxide Semiconductor Field Effect Transistors (MOSFETs). Thus, this paper aims to provide more insights on PD behaviors of aviation wires under high
$\text{dv}/\text{dt}$
PWM excitations and possible ways to improve the existing PD test methods. A test setup including an ultra-high
$\text{dv}/\text{dt}$
PWM generator, a test sample fixture, and associated PD sensors including a photomultiplier tube (PMT), a high frequency current transducer (HFCT), and an ultra-high-frequency (UHF) antenna will be introduced. Experimental results and associated analysis for aviation wire test samples at various pressures under high
$\text{dv}/\text{dt}$
PWM excitations will be presented. The effect of the rise time of the PWM will be discussed in detail. Suggestions on how to improve test methods and test standards will be provided.