Research on Non-contact Condition Monitoring of Converter IGBTs Based on High-frequency Switching Oscillations

Insulated gate bipolar transistor(IGBT) is the core device of medium-to-high power electronic power converters. In order to enhance the safety and cost-effectiveness of IGBT condition monitoring, a non-contact condition monitoring technique for three-phase two-level converters based on high-frequency switch oscillations is proposed. This technique utilizes dedicated sensors to first measure the high-frequency oscillation current generated by the PWM switch voltage of the converter in a non-contact manner. Then, it achieves the localization of all IGBT switch events in the converter under the condition of no gate signals by the polarity relationship between the three-phase high-frequency oscillation and the fundamental current. Finally, the IGBT turn-off time is detected based on the characteristic detection of transient inflection points in the oscillation signal. Based on the above technical principles, a non-contact IGBT condition monitoring device is built for converters on an embedded platform and carries out technical verification on a 380 V/3 kW variable frequency motor towing platform. The experimental results show that the device can implement online monitoring of the switching characteristics and health condition of the six IGBTs in the inverter of the frequency converter, with advantages such as safety, accuracy, and cost-effectiveness.