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DC circuit breaker is the key equipment to deal with the interruption of short-circuit current. Compared with the mechanical switch, the solid circuit breaker and the hybrid circuit breaker using the semiconductor device to interrupt the short-circuit current exhibit superiorities in response duration and arc-less characteristics. Massive power devices controlled by corresponding gate drivers which make the semiconductors-based dc circuit breaker bulky and costly are required to withstand the high dc-bus voltage. In this article, the master−slave concept based modular circuit breaker is proposed to simplify the gate driver topology. Only one single gate driver is required to control highly compact modular submodules consisting of power devices, passive components, and diodes. Moreover, the proposed topology can be easily implemented with high flexibility and low cost. Specifically, the gate control function and voltage equalization for series-connected devices can be realized reliably. The master−slave concept and operation principle of the proposed topology are elaborated and the effectiveness has been demonstrated by both simulation and experimental test. [ABSTRACT FROM AUTHOR]

High-voltage direct current (HVDC) circuit breaker development and deployment strongly depend on the testing process, which ensures that the HVDC circuit breakers will satisfy design requirements. This article presents an HVDC circuit breaker test bench circuit configuration that can provide controllable large output currents to simulate different fault conditions for the current breaking test and high output voltage for the dielectric withstand test. The current breaking test circuit is based on multiple cascaded power converters connected in parallel to provide the necessary output current capability. Each cascaded power converter is composed of multiple cells that are operated by a phase-shifted pulsewidth-modulated signal for greater controllability and higher quality of the output waveform. The dielectric withstand test circuit is a simple high-voltage source with a low power rating that can also be used to charge the test bench and the internal circuitry of the circuit breaker that is to be tested. The proposed test bench ensures that fault conditions can be replicated accurately and offers greater flexibility by being able to test mechanical, semiconductor-based, or hybrid HVDC circuit breakers with different current and voltage ratings on the same hardware without any changes. The idea and the operating principle of the proposed test bench are verified experimentally on a downscaled system that consists of three cascaded power converters connected in parallel with three cells per cascaded power converter and with a total equivalent switching frequency of 92.5 kHz. [ABSTRACT FROM AUTHOR]