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.

DC-DC converters and DC solid-state circuit breakers are critical to the stable operation of DC microgrids. However, they can interact with each other when cascaded, causing problems such as the inability of circuit breakers to isolate short-circuit faults or the amplification of converter output ripple. In order to solve the above problems, an integrated design scheme based on Z-source DC solid-state circuit breakers and DC-DC converters is proposed and applied to the Cuk converter in this paper. The proposed topology achieves functional integration by multiplexing the coupled inductors in Z-source circuit breaker with the inductor in Cuk converter. This scheme guarantees two performance targets, reducing the size footprint and achieving low-pass filtering characteristics. By comparing and analyzing the operation condition in steady state of the proposed topology with the Cuk circuit, the mathematical model is established, and its feasibility is verified by theoretical derivation. Finally, the simulation model is built on MatLab/Simulink, and the simulation results prove the correctness of the theoretical derivation.

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.

The DC circuit breakers play a key role in the performance of the fuel cell electric vehicle. The DC circuit breaker can quickly isolate the short-circuit faults and reduce the damage of the short-circuit current to the fuel cell system. However, traditional DC circuit breakers still have issues, such as complex structure, large volume and weight, and false triggering caused by step load. These problems restrict the further application of fuel cell systems. Thus, this paper proposed a novel Z-source bidirectional DC solid-state circuit breaker (NSCB) applied to the proton exchange membrane fuel cell (PEMFC) electric vehicle. First, a simulation of 72V power supply voltage in Saber was established to verify the validity of the topology. Second, the working principle and process of the novel circuit breaker were analyzed. Third, this paper described how to choose the parameters of the transformer. Then, this paper analyzed the maximum fault resistance of the novel circuit breaker. Finally, the impact of the capacitor values on the circuit breaker was explored. With the help of simulation analysis, it can be seen that the novel Z-source bidirectional DC circuit breaker proposed in this paper has an excellent capability to isolate faults and can effectively protect the fuel cell system.