Design of brushless PM motor for high starting torque requirement for aircraft applications

This paper discusses the design of a brushless permanent magnet motor in which the performance requirement is dominated by breakout torque. It discusses the impact of a rotor position feedback error and how it affects the machine sizing in order to overcome breakout torque requirements. It is shown that the brushless AC drive is less sensitive to the position error compared with the brushless DC drive, and it could provide a 11% increase in breakout torque capability for a given position error and RMS current. The effect of a conductive rotor sleeve on torque ripple is also analysed. Testing with a prototype system verifies the results.