Intelligent, compact and robust semiconductor circuit breaker based on silicon carbide devices

A novel semiconductor circuit breaker based on SiC (silicon carbide) is introduced in this paper. It integrates an electronic power circuit breaker consisting of two anti-serial cascodes, a control unit with current, voltage and temperature measurement as well as a power supply, making the switch fully self-sufficient. Each cascode is composed of a high-voltage SiC-JFET (junction field effect transistor) or a SiC-SIT (static induction transistor) and a low-voltage Si (silicon) - MOSFET (metal oxide semiconductor field effect transistor), resulting in a normally-off configuration. This new circuit breaker has further advantages over well-known alternatives such as noiseless switches without electric arcs. Highest selectivity minimizes short-circuit currents and thus the stresses on electrical equipment. The integrated current and voltage measurement function allows the effective and apparent power to be determined. The switch can therefore actively influence inrush currents, resulting in better net exploitation. The benefits of using silicon carbide power semiconductors include a significant reduction of forward losses, which are the biggest drawback of electronic switches compared to mechanical ones, and the high ruggedness achieved by their intrinsic short-circuit capability for a period of time sufficient for the control unit to switch the devices off electronically. Its current and temperature measurement capability additionally assures overload protection by tracking the junction temperature within a digital model calculated by the control unit. Measurements at different operating points and in fault cases have been performed on prototypes of this novel semiconductor circuit breaker. The results show conclusively that this approach represents the next step forward to a perfect electronic circuit breaker.