Electromagnetic and thermal coupling within a fault-tolerant aircraft propulsion motor

This paper describes the development of a fault-tolerant, high specific output motor for use in aircraft electrical propulsion. The program includes demonstration of a full scale propulsion motor to a specification representative of an electric tail rotor drive on a medium twin-engine helicopter. The safety critical nature of the application demands a redundant system architecture comprising four 3-phase motor channels integrated within a single air-cooled housing. A modular wound 24 slot, 28 pole brushless AC permanent motor design is selected for this purpose. In principle the topology should ensure minimal interaction between the phase coils. The degree of electrical and thermal coupling between the four independent motor channels is explored in this paper, during normal and faulted operation. The findings are accompanied with test results taken from the full-scale prototype machine.