ABSTRACT High‐voltage power semiconductor devices are subjected to repetitive frequency square‐wave pulse voltages during actual operation, making the online assessment of their packaging insulation material degradation challenging. Based on the principle of charge–atom coupling, this paper proposes a novel assessment method utilising molecular vibration acoustic waves induced by forced charge motion at square‐wave pulse edges. By directly employing the rising and falling edges of high‐voltage square‐wave pulses inherent in device operation as excitation sources, this method stimulates molecular chain vibrations within the insulation material and achieves in situ degradation assessment through synchronous detection of acoustic signals. Results indicate that pulse repetition frequency has no significant effect on vibration amplitude; vibration amplitude is proportional to the square of the pulse voltage amplitude and temperature exhibits different effects on the two materials—silicone gel shows a monotonic increase in vibration amplitude with rising temperature, whereas silicone rubber initially increases and subsequently decreases. Under fast edge excitation, low cross‐linking density insulation materials exhibit a double‐peak waveform, whereas high cross‐linking density materials consistently exhibit a single‐peak waveform. This phenomenon reveals intrinsic differences in material chain segment dynamics, providing a new technical pathway for the online monitoring of power device insulation systems without requiring external Gaussian pulse generators.
He et al. (Thu,) studied this question.