Emerging applications of compact high-voltage SiC modules pose strong challenges in the module package insulation design. Such SiC module insulations are subjected to both high-voltage dc and pulsewidth modulation (PWM) excitations between different terminals during different switching intervals. High dV/dt strongly interferes with partial discharge (PD) testing as it is hard to distinguish PD pulses and PWM excitation-induced interferences. This article covers both the testing and modeling of PD phenomena in the high-voltage power modules. A high dV/dt PD testing platform is proposed, which involves a super-high-frequency (SHF) (SHF >3 GHz) down-mixing PD detection receiver and a high-voltage scalable square wave generator. The proposed method captures SHF PD signatures and determines PD inception voltage (PDIV) for packaging insulation. Using this platform, this article provides a group of PDIV comparisons of packaging insulation under dc and PWM waveforms and discloses discrepancies in these PDIV results with respect to their excitations. Based on these PD testing results, the article further provides a model using the space-charge accumulation to explain the PD difference under dc and PWM waveforms. Both simulation and sample testing results are included in this article to support this hypothesis. With this new model, the article includes an updated insulation design procedure for the high-voltage power modules.

Wide band gap (WBG) power electronic devices, such as silicon carbide metal–oxide–semiconductor field-effect transistors (SiC MOSFETs) and gallium–nitride high-electron-mobility transistors (GaN HEMTs) have been widely used in various fields and occupied a certain share of the market with rapid momentum, owing to their excellent electrical, mechanical, and thermal properties. The reliability of WBG power electronic devices is inseparable from the reliability of power electronic systems and is a significant concern for the industry and for academia. This review attempts to summarize the recent progress in the failure mechanisms of WBG power electronic semiconductor chips, the reliability of WBG power electronic packaging, and the reliability models for predicting the remaining life of WBG devices. Firstly, the typical structures and dominant failure mechanisms of SiC MOSFETs and GaN HEMTs are discussed. This is followed by a description of power electronic packaging failure mechanisms and available packaging materials for WBG power electronic devices. In addition, the reliability models based on physics-of-failure (including time-dependent dielectric breakdown models, stress–strain models, and thermal cycling models), and data-driven models are introduced. This review may provide useful references for the reliability research of WBG power devices.

Partial discharge (PD) in the high voltage packaging insulation under square pulse with a high slew rate (SR or dV/dt ) is one of the main causes of the power module failure, especially for wide bandgap devices. But, PD under fast square pulse at high temperatures is rarely studied and one of the critical reasons is the lack of an effective PD detection method under fast square pulses. In addition, the existing PD standard defines the PD criterion under sinusoidal alternating current (ac) situations, which is not the actual working condition of the power module. To address that, this article proposes a down-mixing PD detection method and explores the influence of temperature on the PD characteristics of the power module packaging insulation. The results show that the partial discharge inception voltage (PDIV) decreases as the temperature increases. The PDIV under square pulse is always higher than that under ac voltage. The less the SR and the greater the pulsewidth of the square pulse, the lower the PDIV. Physical-based models for PDIV estimation concerning SR, PW, and temperature are proposed for industrial reference. Moreover, statistical analysis of PD magnitude, number, and occurrence phase under square pulse indicates that PD number decreases but PD magnitude increases with the increase in temperature. Higher temperature leads to PDs with large magnitudes, which may accelerate the degradation of packaging insulation.

Electric machines with high specific power are crucial for more electric aircraft propulsion. However, the harsh operating environment such as low air pressure and high temperature will challenge the motor's insulation system and cause partial discharge (PD), which threatens the reliability of the machine. This paper proposes a PD-free stator winding design regarding an air-core high-frequency permanent magnet synchronous machine for aircraft propulsion. The experiment and simulation are performed under sinusoidal voltage due to the power quality requirement by the standard for aircraft. Partial discharge inception voltage (PDIV) with respect to air pressure and temperature was obtained experimentally for form-wound windings and was analyzed to derive the PD-free criteria. A 3-D stator model was built and used to simulate the electric field and temperature distribution with a finite element method. In addition, the effect of voids and delamination on electric field distortion was also taken into consideration to allow for a safety margin and meet the PD-free requirement. To achieve high specific power and PD-free requirement simultaneously, a multi-objective genetic algorithm was adopted to perform the optimization and obtain the Pareto fronts at various air pressures. Finally, the PDIV value of the designed winding was measured to verify the PD-free design. The main purpose is to combine the experimental results and the simulation tool to obtain an acceptable PD-free design in the meantime achieving high power density, which may provide helpful guidance on motor insulation design for the more electric aircraft propulsion.

Electric machine for aircraft propulsion is required to have high power density and high reliability, but the harsh operating environment, such as low air pressure, will challenge the motor's insulation system. This study presents the partial discharge (PD) investigation of the form-wound winding in high-frequency electric machines for electric aircraft propulsion. Experimental results show the PD activity is largely enhanced due to the decrease in air pressure. Partial discharge inception voltage (PDIV) decreases to 50-60%, and the PD magnitude dramatically increases when the pressure drops from 1 to 0.2 atm. Several windings with introduced defects were also tested to extract features from phase-resolved partial discharge (PRPD) analysis, which can be used for PD pattern recognition. In addition, a PD based failure precursor, combining the apparent charge, number, and phase interval of the monitored PD profile, is proposed to monitor the insulating condition of the thermally and electrically aged windings. The proposed failure precursor generally shows a rising trend with the aging time in this paper. The application of the proposed failure precursor on online condition monitoring needs more investigation through long-term online observation of the electric machine.

The laying of power cables is a crucial aspect of developing and maintaining modern electrical infrastructure, which is vital for transmitting electricity reliably and efficiently. This review discusses the challenges and advancements in cable laying technologies, emphasizing the critical role of these techniques in meeting the increasing demands for power transmission in the backdrop of the global shift to renewable energy. Three main traditional cable laying methods are explored, including underground, overhead, and submarine, each suited to specific environmental and operational conditions. Then, the cable faults due to the impropriate laying process are discussed. Subsequently, the challenges and advancements encountered in cable laying processes are investigated, especially the difficulties of the cable laying of underground cable, submarine cable, and high-temperature superconductivity cable. This review also considers the impact of technological innovations on improving efficiency in cable laying processes, highlighting the advances driven by digitalization and automation.