Thermal Analysis of An Ultra-Fast Low-Voltage Hybrid DC Circuit Breaker

Compared with solid-state circuit breakers, hybrid circuit breakers (HCBs) combine the advantages of fast mechanical switches (FMSs) and power electronic devices, which have lower conduction losses and can isolate faults quickly as well as reliably. Therefore, HCB is increasingly used in ship power systems, electric vehicle charging infrastructure and aircraft and railway systems. With the advanced performance of FMS, HCB based on FMS and power electronic devices is expected to achieve faster fault breaking speed in the low-voltage field. However, for FMS-based HCB, it is still a problem to ensure that the steady-state temperature rise under higher rated current is up to standard. In this paper, the thermal performance of an ultra-fast low-voltage hybrid DC circuit breaker is experimentally evaluated under rated current conditions. A finite element simulation model was constructed to estimate the steady-state temperature rise of the prototype at rated current, and the finite element simulation model was corrected by experiments. The finite element simulation model establishment method in this study can be applied to the temperature rise calculation of HCBs, and can further optimize the heat dissipation problem of HCBs through this calculation method, which is helpful to ensure the breaking performance of HCBs and improve their reliability.