The volume and cost of the transformer coupling bridge-type solid-state fault current limiter (SSFCL) depend on the components of the fault current limiter including the series coupling transformer

rectifier bridge and current-limiting inductance. To reduce the volume and cost of the coupling transformer

a novel auto-transformer coupling bridge-type SSFCL is proposed with a detailed analysis of its working principle and current-limiting process. For the problem of large current-limiting inductance due to the inability of rectifier bridge thyristor to control the turn-off

the topology of the secondary side of SSFCL is improved by using full-controlled power electronic devices. The improved topology has the ability to shorten the time for the bridge and current-limiting inductance to withstand the inrush current while reducing the amplitude and the slope of inrush current. Thus

the related parameters of power electronic devices in rectifier bridge and current-limiting inductance can be decreased and the cost of SSFCL further cut. Simulation results show that SSFCLs with auto-transformer are more efficient and cost-effective than those with normal transformer with the same current-limiting objective. The effectiveness of the improved SSFCL is validated by experiment. This work is supported by National High Technology Research and Development Program of China (863 Program) (No. 2012AA050402).