High Reactance PMG and Single-stage Converter based Aircraft Electric Dual Mode Generation System

The use of permanent magnet generators (PMG) in aircraft electrical systems is receiving attention due to their high specific output alongside a simple and robust rotor construction. Their fixed uncontrolled excitation requires additional power converters to regulate the AC supply, and the convention is a backto-back arrangement of an active rectifier followed by a DC to AC inverter, each fully rated. In this paper an alternative architecture is explored, comprising a high reactance PMG and a parallel connected active shunt regulator (ASR). As only a single AC to DC power converter is required, the system complexity, weight and power conversion loss is reduced. Due to the shunt configuration the ASR can be rated below the generation system capacity, providing further weight savings. The system can also provide an engine start function when connecting with 270 VDC bus. The working principles of the PMG plus ASR arrangement are presented together with experimental results from a 45 kVA, 115 V, 400 Hz generation system prototype.