Variable-speed induction motor drives for aircraft environmental control compressors

System analysis and engineering have determined that electrically-driven environmental control system (ECS) can help to maintain the improved fuel efficiencies; and electronic controllers and induction motors are now being developed in a NASA/MPD SBIR Program to drive both types of ECS compressors. An important operational requirement for these applications is variable speed/load operation; and total maximum power outputs are under 200-kW for cabin pressurization and 100-kW for vapor cycle compressors, divided among four redundant units in a typical, 300 passenger, wide-body design. Typical speeds for full output of aircraft centrifugal compressors are in the 50000-RPM range. The application area addressed is characterized by slowly-changing inputs and outputs, small reserve power capability for acceleration, and optimization for maximum efficiency. This paper therefore focuses on the differences between this case and the optimum response case, and shows the development of this new motor/controller approach. It starts with the creation of a new set of controller requirements. In response to those requirements, new control algorithms are being developed and implemented in an embedded computer, which is integrated into the motor controller closed loop. Buffered logic outputs are used to drive the power switches in a resonant-technology, power processor/motor-controller, at switching/resonant frequencies high enough to support efficient high-frequency induction motor operation at speeds up to 50000-RPM