The emerging interconnections of renewable energy sources that generate DC power have resulted in demands on DC grid systems. In this situation, a low-voltage DC (LVDC) grid system could be a solution for these DC power sources. For the reliable operation of a LVDC grid, DC faults are an issue and DC circuit breakers (DC CBs) are appropriate devices to clear fault current. However, there are some difficulties in terms of breaking DC faults such as the absence of zero crossing of the current and voltage, and the high di/dt of the fault current. This paper proposes a hybrid circuit breaker (HCB) with a new structure for a LVDC grid system. The main switch consists of a vacuum interrupter (VI) and a permanent magnetic actuator (PMA). Some improvements are proposed to enhance the performance of the PMA. A bi-directional commutation loop consisting of a minimum number of power electronic devices is suggested. To absorb fault energy, a capacitor and a diode loop are applied. The principle of the proposed HCB and the design methods for all of the components are analyzed. Through a simulation model, the designed components are selected and verified. Experimental results with a realized prototype (750 V/300A) verify the design method and its performance.

产生直流电的可再生能源的新兴互连导致了对直流电网系统的需求。在这种情况下，低压直流 (LVDC) 电网系统可能是这些直流电源的解决方案。为了 LVDC 电网的可靠运行，直流故障是一个问题，直流断路器 (DC CB) 是清除故障电流的合适设备。然而，在断开直流故障方面存在一些困难，例如没有电流和电压的过零，以及故障电流的高 di/dt。本文为 LVDC 电网系统提出了一种具有新结构的混合断路器 (HCB)。主开关由真空灭弧室 (VI) 和永磁执行器 (PMA) 组成。提出了一些改进以提高 PMA 的性能。建议使用最少数量的电力电子设备组成的双向换向回路。为了吸收故障能量，应用了一个电容器和一个二极管回路。分析了所提出的 HCB 的原理和所有组件的设计方法。通过仿真模型，选择并验证设计的组件。已实现原型 (750 V/300A) 的实验结果验证了设计方法及其性能。