A passive current limiter for power semiconductor protection

Static power converters are being used increasingly in power system applications. The power semiconductor switches within these converter systems accommodate power system fault overvoltages. Significant cost reductions can be attained by reducing the magnitude of power system fault currents. In this paper, the authors propose the use of a novel passive current limiter to accomplish this task. The limiter consists of two magnetic devices connected in series and in magnetic counter opposition to each other. Each magnetic device consists of three slices of NdFeB permanent magnet material sandwiched between the three end poles of two ferrite E cores. Experimental and finite element results are presented and are found to be in good agreement with each other. The need for 3D modeling in the future is demonstrated. The operating characteristics of the current limiter are experimentally verified using a scaled down version of a power system.