Phase-Coupling Effects in Three-Phase Inductive Fault-Current Limiter Based on Permanent Magnets

In this article, a novel concept of an inductive, saturated-core fault-current limiter (FCL) design is presented, capable of limiting three-phase faults. The design is based on high-remanence permanent magnets for biasing high-saturation electrical steel cores, thus minimizing the device volume, dimensions, and cost and allowing a relatively easy assembly process due to the magnetic symmetry of the model. By implementing a three-phase design in a single device, we harness the full potential of each magnet, substantially reducing the required material for achieving negligible losses during nominal operation while increasing current limiting during faults. A laboratory-scale, low-voltage prototype has been built and tested to prove the feasibility of the new concept, suggesting that upscaling to higher voltage devices is plausible. Extensive simulations, using finite-element analysis, have yielded insight into several measured phenomena, including a unique phase-coupling effect experienced during three-phase fault measurements.