LAUSR

This article deals with the design of an electronic fuse for 380 V dc distribution systems. It has been devised for applications that require current limitation up to 3 A, so approximately 1.2 kW. To protect the main semiconductor against excessive energy dissipation, the tripping time, defined as the time that circuit operates in current-limitation mode, varies with the current fault magnitude, and eventually for very hard fault conditions, i.e., short-circuit, the circuit acts as a circuit-breaker avoiding current-limitation operation. Furthermore, thermal foldback characteristic, defined as the variation of current limitation setpoint with temperature, and tripping time variation with temperature are also considered. Mathematical analysis, circuit design, simulations, and experimental validation have been carried out using a SiC MOSFET as power semiconductor. Experimental results working under different conditions show an excellent performance.