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The electric vehicles (EVs) have been helping to alleviate the pressure of the world energy crisis. However, the insulation of EVs driving motors usually suffers from the electrical stress caused by partial discharge (PD) during the operation. Aramid paper in the stator can reduce the incidence of electrical degradation. In this context, PD characteristics, topography and chemical groups changes of Aramid paper under AC and repetitive nanosecond impulse voltages were compared. The results illustrated that the increase of ambient temperature will promote the activity of PD under AC voltage. The PD magnitude under nanosecond impulse voltage is almost 100-fold that under AC voltage. PD caused by nanosecond impulse voltage leads to more severe destroy of chemical groups and higher roughness. This investigation offers an important reference for exploring the electrical aging of Aramid paper for the slot of stator in EVs motor.

Partial discharge (PD) detection in high voltage power equipment is significant as it provides most early information on the degradation characteristics. A fiber optic Fabry-Perot (F-P) sensor based on charge-coupled probe is designed to detect PD signals under pulse square voltage. When the PD signal acts on the probe, the potential difference induced by the probe leads to the deformation of the piezoelectric diaphragm, which further results in the change of light intensity signal. Thus, PD detection could be realized by converting the light intensity signal into a voltage signal. In this study, the discharge impulse signal under various voltage frequencies (50 Hz, 5 kHz, 10 kHz) have been monitored by the F-P sensor and the ultrahigh frequency (UHF) antenna. Compared with the UHF antenna, the average measured magnitude of PD signals detected by the F-P sensor is increased by 23.1%.

The measurement of the surface charge on the insulating dielectrics is critical to estimate the insulation strength of electrical equipment in operation. Unavoidable interactions with the electromagnetic field, however, generally result in distortion measurement of active sensor. Thus, it is of great significance to investigate a passive sensor for monitoring the deposited charge. Here, a passive optical fibre electrostatic sensor is developed on the principle of Fabry–Perot interference to quantify the surface potential of the insulating dielectrics. The sensitivity of quantifying the electrostatic charge is explored in terms of the wavelength shift in the interference spectrum, and the linear correlation is 0.99. Meanwhile, the sensor can identify a negative quadratic trend with the increase of the surface roughness of the insulating dielectrics. The merits of the proposed sensor such as passive monitoring, bipolar electrostatic detection, and the excellent ability of anti‐electromagnetic interference are highlighted in the results. Hence, this sensor can serve as an effective tool to monitor the electrostatic charge in the fields of smart electrical equipment, fuel transportation, aerospace, integrate circuit etc.

Surface charge accumulation and transport on the cellular polypropylene play an important role in nanogenerator, which could have a potential impact on energy harvesting and wearable devices for zero carbon energy systems and internet of things. Different shapes have different charge accumulation and decay characteristics of the polymer. Therefore, we studied the influence of the sample’s shape on the surface charge decay by experiment and modeling. The surface potential of square and circular cellular polypropylene was measured by a two-dimensional surface potential measurement system with electrostatic capacitive probe. The experimental result shows that the surface potential distribution of the square sample dissipates non-uniformly from the bell shape to one side collapsed shape, while that of the circular sample dissipates uniformly from the bell shape to the crater like shape. Moreover, the simulation results of the initial surface potential distributions of the square and circular cellular polypropylene are consistent with the experimental results. The investigation demonstrates that the charge transport process is correlated with the shape of the sample, which provides significant reference for designing electret material used for highly efficient nanogenerator.