Novel Simulation Model for Coil-Coil Type Electromagnetic Repulsion Actuator in Low Voltage DC Circuit Breaker

Cooperating with secondary protection system, DC circuit breakers are used to deal with direct current (DC) faults in low voltage DC distribution system. To realize ultra-fast operating of DC breakers, optimization based on simulation of coil-coil type electromagnetic repulsion actuator (EMRA) is discussed in this paper. Considering exiting simulation based on finite element method (FEM) is quite time-consuming, an equivalent circuit method (ECM) for the Coil-Coil type EMRA is established. In the equivalent circuit equation, lumped equivalent inductance which contributes to the induced electromotive force (EMF) is used to reflect the coupling effect of distribute electromagnetic field on electric circuit, the gradient of equivalent inductance which contributes to the motional EMF reflecting the coupling effect of mechanical motion on electric circuit and the equivalent resistance that varies with temperature reflecting the coupling effect of temperature field on electric circuit. The lumped equivalent inductance and its gradient are extracted by solving static magnetic field based on FEM. By solving the state equations, the transient electrical and operating characteristic of EMRA are obtained. In the end, the results of the model based on ECM are compared with FEM, and as expected, they are in good consistence.