Fault-tolerant inverter for on-board aircraft EHA

In more-electrical aircraft, most of the flight surfaces are equipped with electro-hydrostatic actuators. A high reliability is mandatory, combined to fault-handling strategies for the VS inverter, which is a part of crucial importance of this equipment, controlling the power flows and the performances. The proposed topology uses a safe fourth-leg connected to the star tap of a standard PMSM winding. Fault-handling IGBT drivers and isolating AC switches are introduced in series with all the legs so as to confine a local inverter fault and to manage the post-fault operation. A modular and versatile design is proposed, based on a generic set of two legs including a local over-current / temperature monitoring and an optional self isolation capability under fault. In this paper, the authors present a complete lab test-bench, the DSP-FPGA digital control including a state chart and finally results in post-fault two-phase reconfiguration.