The current commutation characteristics of DC micro-grid hybrid circuit breakers

The paper focuses on the current commutation between the vacuum arc and the IGBTs of DC micro-grid hybrid circuit breakers (HCB). The principle of the DC HCB is analyzed and the current commutation is the important process in DC HCB interruption, on which the arcing time and the interrupting time are depended. The test circuit of the current commutation is established by simplifying the parallel-connected IGBTs to an on-state resistance with large thermal capacity. The influence of the magnitude of the main current, the resistance of the IGBTs and the externally applied transverse magnetic field (TMF) on the current commutation is investigated by the electrical measure and the development of vacuum arc which is observed by a high speed CMOS camera. The mathematic description of the current commutation is obtained. The interaction between the vacuum arc commutation and the externally applied TMF is discussed. The paper provides the bases on the optimal design and control strategy of DC HCB.