A Switching Oscillation Event-Triggered Switch Fault Detection Method for SiC DC–DC Converter

Switch fault detection is critical for the safety and reliability of a SiC dc–dc converter, which is however difficult by directly comparing the PWM voltage and the gate signal due to the harsh electromagnetic environment and ultrahigh switching frequency. To address the challenges, a novel method is proposed to detect and diagnose the switch fault using the converter PWM high-frequency (HF) switching oscillation. First, the switching event status in a SiC dc–dc converter is captured from the HF switching oscillation current in a noncontact way. Then, the switch fault is detected and diagnosed by checking the signal integrity of the switching events with no need for a gate signal. Finally, a switching oscillation event-triggered switch fault detection system is developed including the HF oscillation sensor, switching event capture circuit, and switch fault detection and diagnosis unit. Experimental work is carried out and the results demonstrate the performance of the method with high safety up to MHz.

I. Introduction

Silicon carbide (SiC) metal-oxide-semiconductor field effect transistor (mosfet) is a popular bandgap semiconductor device [1], [2], [3] featuring superior efficiency and high-temperature capability [4]. Recently, there is a trend to replace traditional Si-based power devices with SiC mosfets in high-power-density and/or high-efficiency systems, such as electric vehicles, renewable energy systems, and more electric aircraft. However, reliability issue is one of the main challenges for large-scale applications of SiC mosfet due to its fast switching, thin gate-oxide, and smaller chip size [5], [6], [7]. It is estimated that about 38% of the faults in variable-speed ac drives in industry are due to failures of power devices [8]. In [9], an industry-based survey indicates that power devices are the most fragile components (about 31%) across different industry sectors. Thus, switch fault detection is important for the safe and reliable operation of power converter systems [10], [11].