Y-Source Bi-directional DC Circuit Breaker

Abstract

Y-source impedance network topology is proposed to be a bi-directional DC circuit breaker. In this paper, there are three coupled inductors formed in a Y shape with a capacitor to achieve a two sides symmetrical impedance. It has a capability to pass the DC current in both directions. The input impedance, voltage, and current transfer function are presented to evaluate the breaker operation. The limitation and minimum slope of the fault conductance have been derived. According to the mathematical results, the breaker is able to interrupt the source current in case of passing a portion above the normal load current or higher. This breaker has a feature that the high gain-reverse current is produced by two secondary windings. The gain reversible current magnitude depends on turn ratio of the three windings. This current reduces the silicon control rectifier (SCR) current less than its holding current with enough time to turn OFF. The breaker clears the fault current in both directions automatically and quickly before the source experiences the abnormal current. Simulation results show that the performance of the proposed breaker under fault and load change conditions to verify the mathematical analysis.