Novel lightweight aircraft electric starter
Europe's aircraft industry has committed to revolutionise energy systems on board aircraft through gradual replacement of hydraulic, pneumatic and mechanical power with electricity. Unfortunately, implementation of this concept using conventional components revealed that the weight increase of more-electric aircraft offsets any savings offered by higher efficiency. Within the EU-funded project AEGART (Aircraft electrical generation system with active rectification and health monitoring), scientists developed a new system that results in considerable starter-generator weight saving, without compromising aircraft safety and reliability. The novel generation system comprises an electric machine, power electronic converter, associated cooling system and control with health-monitoring functions. An important part of the work was geared towards optimising machine design by introducing an active converter, particularly for starting-mode operation. Scientists carefully addressed machine efficiency and losses, torque density, thermal dissipation and cooling arrangements. Compared to current autotransformer-rectifier units, this converter increases power conversion efficiency and eliminates the need for passive filters, thus reducing the starter-generator system weight. The novel generation system also boasts features never seen before. Some of these are engine starting with controlled acceleration, operation in either stand-alone or parallel mode, load sharing and slew rate limitation. In addition, the starter-generator's fault-tolerant design and health-monitoring techniques ensure safety and reduce the total weight and volume. Project findings present a significant step beyond the state of the art in aircraft alternator design and power conversion systems and their thermal management. Significant weight and cost savings could be achieved in future more-electric aircraft with reliable, effective, safe and low-maintenance operation of the electric generator.
Keywords
Aircraft, starter-generator, AEGART, generation system, health monitoring, power conversion