The urgent demand for capacitive energy storage at elevated temperatures is limited by significant leakage currents in existing polymer dielectrics, which lead to excessive heat generation and increase the risk of thermal runaway. Here we demonstrate a strategy to mitigate conduction loss by modulating energetic disorder within the polymer matrix. Incorporation of high-polarity organic molecules into polyetherimide enhances dipole-dipole interactions, increasing energetic disorder and thereby decreasing charge carrier mobility. Experimental measurements and computational simulations reveal that disorder-induced energy fluctuations broaden the energy separation between transport states, effectively suppressing charge transport. The resulting composite delivers an energy density of 6.45 J cm⁻³ with a charge-discharge efficiency of 90% at 200 °C, and exhibits stable performance over 100,000 cycles under an applied field of 400 MV m⁻¹. The observed uniformity and quality of the all-organic composite films address the challenges of scalable manufacturing for dielectric films, offering a practical pathway for the development of high-temperature dielectric materials.

The switching oscillations caused by the high-speed switching and low-damping characteristics of SiC mosfet seriously deteriorate its high-reliability applications. By viewing from the terminals of both SiC mosfet and diode for the turn- on and turn- off oscillation not only the two-port networks be formed to carry out more accurate analysis about the system characteristics but also the characteristic equations of the system can be deduced, thereby reliably guiding the RC snubber design. Since the oscillation is essentially caused by the imaginary part of poles, with the assistance of the two-port networks, an optimized design method of an RC snubber circuit is developed by the way of actively assigning poles. Different from existing analytical techniques, no necessity is needed to reduce the order of characteristic equations to yield the mathematical expressions of RC snubbers. Instead, RC snubber regions where oscillations can be completely suppressed are determined directly by an exhaustion method. An overlapping area is found, which means that both the turn- on and turn- off oscillation can be eliminated simultaneously by the same snubber circuit. Moreover, the related discussions about existence conditions of the snubber region, sensitivity to parameters, and the limitation in choosing RC are illustrated in detail. Finally, standard double-pulse tests are conducted on both the LTspice simulation and the laboratory experiment to verify the effectiveness of the analysis and proposed method.

The interaction between A-MoO₃ dianhydride monomer of PEI results in the establishment of an intrinsic electric field between the PEI matrix and A-MoO₃, effectively inhibiting the release of trapped electrons.

Leakage current issues are worthy of attention for nonisolated grid-connected systems. This article introduces the method of eliminating common-mode (CM) voltage and reducing the leakage current based on modulation, and analyzes the correlation between actual effects of the method and the flying capacitor (FC) voltage balance in three-phase three-level FC grid-connected inverter. The proposed carrier-based modulation can balance the FC voltage by changing the transmission sequences of pulses and theoretically achieve zero CM voltage. In order to deal with the low frequency fluctuation and bias voltage of FC caused by asymmetry of actual hardware, the control method is introduced, which controls FC voltage by changing the action times’ distribution of switches, while still eliminating the CM voltage. Simulation and experimental results are provided to validate that the proposed method can control FC voltage and achieve good performance in suppressions of CM voltage, leakage, current and CM electromagnetic interference noise.

Zero voltage switching (ZVS) control is an effective and promising way to further improve the power density, efficiency and electromagnetic interference for the two paralleled silicon carbide inverters with coupled inductors. In this article, focusing on the popular 180 ^o interleaved pulsewidth modulation (PWM), the circulating current ripple prediction model is first derived as a function of operating conditions in the time-domain. With the assistance of this model, the actual trajectory of phase-leg currents can be reconstructed by superposition of sampling fundamental current and predicted circulating current ripple, without adding any high-frequency current sensor or auxiliary circuit. By carefully considering the ZVS requirement of all switches, a variable switching frequency PWM (VSFPWM) for full range ZVS control is proposed in this article. The proposed VSFPWM shows a good performance of ZVS realization in various load situations, as well as a good dynamic response of the inverter during current step change. In addition, due to the real-time variation of switching frequency, the proposed VSFPWM demonstrates the obvious advantage in conductive EMI reduction. Both the simulation and experimental results are presented to verify the effectiveness of the analysis and proposed method.