Innovative strategies for protecting power semiconductor switches for phase balancing and feeder balancing in aircraft

Abstract

An inflexible point-to-point supply of loads is the state-of-the-art technology in aircraft nowadays. Because the wiring is rigid, it is not possible to connect loads to different power feeders when the aircraft is in flight. New technologies are required for handling the increasing demand for electricity on board aircraft. Two concepts - phase balancing and feeder balancing - which lead to an energy-efficient power supply network, are introduced. Both methods use intelligent switching nodes with power semiconductor devices, such as MOSFETs. The power transistors are chosen in such a way that they are slightly above the limits for forward current, blocking voltage and switching frequency. The number of switching operations that produce overvoltages and overcurrents in the electrical grid increases if the concepts that have been presented are used. To ensure that the transistors operate in their safe operating area, snubber circuits are used. Since the switching nodes bring in additional weight, these snubbers have to be designed in such a way that they are sufficiently light. Based on an analytical examination of switching ohmic-inductive and ohmic-capacitive loads, different switching strategies for reducing the negative switching effects have been introduced. Computer simulation results have been presented and evaluated.