Abstract
Abstract Space charge behavior under combined high-frequency electrothermal stress is an important causative factor for insulation failure in high-voltage power electronic equipment. In this research, a novel charge transport model adapted to the high-frequency stress environment is developed. Modifications are implemented in the model to address the high-frequency stress characteristics, namely for the electrothermal coupled stress environment, high-frequency injection, flexible migration, and interfacial features. The study examines the evolution of space charge influenced by polarisation parameters, including frequency, duty cycle, and polarisation polarity. The results indicate a disparity in charge accumulation polarity under uni/bipolar stress. The electric field distortion induced by heteropolar charge accumulation under bipolar stresses poses a great challenge to the insulating properties of the interface. Furthermore, both the quantity and depth of charge accumulation exhibit an inverse association with frequency. The minimum accumulation depth is merely 6μm at a polarisation frequency of 1kHz. Conversely, the extent of charge accumulation escalates exponentially with an increase in the duty cycle (stress power). Finally, the model reliability is validated by comparing with the high-frequency charge measurement under the relevant parameter. The pertinent research can offer a viable technical approach to elucidate the dynamic behaviour of space charge under high-frequency stress.
Published Version
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