Design and Implemention of Bidirection Solid-State Circuit Breaker for Bipolar DC Bus Micro-Grid System

Design and Implemention of Bidirection Solid-State Circuit Breaker for Bipolar DC Bus Micro-Grid System

A bidirectional solid-state circuit breaker (SSCB) for bipolar DC busmicro-grid system is proposed in this paper. The solid-state circuit breaker adopts MOSFET as the main switches, and actively controls the active snubber circuit to release the inductance energy when the main switches are turned off. The MOSFET will operate in the nonsaturation region when it is turned on at the rated capacity, and operate in the cutoff region when it is turned off. The saturation region of the MOSFET is used to limit the rising rate of the fault current to delay the instantaneous overcurrent. By using the MOSFET drain-source voltage Vds as an overcurrent detection, the proposed SSCB can effectively cut off at the point of failure within microseconds. The proposed SSCB consists of MOSFET, mechanical isolation relay, active snubber circuit, soft start circuit, series limiting inductor, and microchip control processor. The bidirectional SSCB with rated DC voltage of±380 V and rated current of 50 A is built, and the protection functions are tested within the rated current and different overcurrent conditions to verify the feasibility of the proposed solid-state circuit breaker.