DC microgrids have attracted more and more attention due to their excellent performance. However, the development of DC microgrids is restricted by DC short-circuit protection technology. In this paper, a novel bidirectional Γ-source solid-state circuit breaker (BΓSCB) based on three-winding coupled inductors is proposed to ensure the safe operation of DC microgrids. Compared with other solid-state circuit breakers, the novel BΓSCB has a simpler structure and more compact size. First of all, the derivation process and operation principle of the novel BΓSCB topology are elaborated. Then, an accurate mathematical model covering the whole fault transient and considering the reverse-recovery requirement of SCR is established, and the active trigger region is also quantified, which provide effective guidelines for BΓSCB design and component sizing. Finally, the effectiveness of the proposed BΓSCB topology and the accuracy of the modeling method are verified by simulations.

DC microgrid has been applied in various fields due to its high efficiency. The short-circuit fault protection of circuit breakers is significant to the development of the DC microgrid. The existing modeling method for the Q-Z-Source circuit breaker is not accurate enough for guiding a model-based design. In this paper, an enhanced modeling method for the Q-Z-Source circuit breaker is proposed to improve the accuracy of the modeling. The operational principle and circuit analysis are elaborated with mathematical models, which can provide detailed parametric design methods in the short-circuit fault transient. Meanwhile, an optimization method for the total inductance of the circuit breaker implemented by MATLAB is proposed to reduce the weight and volume of the circuit breaker. Finally, Saber-based simulation results are utilized to verify the effectiveness of the modeling method and the parameters design.

Multilevel converters play an important role in power electronic systems. In recent years, data-driven fault diagnosis technologies for multilevel converters have rapidly developed and are generally based on feature engineering and intelligent classification algorithms. However, the fault detection rate, speed, and stability still need to be improved, especially for complex converter systems. In this article, based on a probabilistic autoencoder architecture, an affine-invariant Riemannian metric autoencoder (AIRMAE) is proposed for feature extraction, and combined with classifiers, a supervised learning fault diagnosis method for multilevel converters is constructed. The proposed AIRMAE is able to investigate low-dimensional representations from high-dimensional data manifolds while preserving sufficient valid information. Based on a five-level nested neutral-point piloted converter, the effectiveness of the proposed method is verified by experiments. The performance is superior to that of existing state-of-the-art fault diagnosis methods, with high detection accuracy, good stability, and strong waveform reconstruction ability.

At present, Solid State Power Controller (SSPC) integrated with short-circuit protection function is gradually replacing the traditional mechanical protection device and playing an important role in airborne fuel cell system (FCS). SSPC can quickly isolate short-circuit faults and avoid damage to FCS. However, the response of traditional SSPC is still slow for short-circuit protection, leading to a large fault current. In this paper, a bidirectional DC SSPC for airborne proton exchange membrane fuel cell systems (PEMFC) is proposed. This SSPC adopts a protection scheme based on the current rising rate, which is implemented with high-speed analog devices. Its simulation verification in the power supply system for a fuel-cell-powered unmanned aerial vehicle (UAV) is provided with Simulink. The results show that the protection speed of the scheme is considerably faster than the traditional protection scheme based on the current amplitude. Also, a circuit-level simulation is performed in Saber to show other advantages of the scheme, such as low energy consumption, allowing capacitive load, immunity to noise interference, and the effectiveness of FCS protection.

Energy storage technology is an important measure for power output of new energy generation system. T-type three-level structure is adopt as the topology of energy storage inverter. Mathematical model of grid-connected operation in ABC coordinate system and dq coordinate system is built. A double closed loop control strategy of which inner loop current and outer loop power control is proposed. The simulation model of T-type three-level energy storage converter when in grid-connected is built in MATLAB, and the simulation is completed to verify the correctness of the control strategy. At the same time, the hardware structure and main function are designed. The experimental platform is built to verify the correctness of the proposed control strategy.