Comparison of PM Brushless motors for helicopter tail rotor Fenestron type

This paper presents the design of spoke-type permanent magnet motor for an electrical tail rotor. The electrical machine is designed for air cooling and a high TRV is requested. The design should guarantee a high reliability due to the safety critical system definition for a tail rotor and should match a given envelope to allow a substitution of the actual mechanisms. In order to obtain high torque maintaining small overall dimensions of the motor, a spoke-type solution with interior PMs has been chosen and compared with a V-shape type arrangement of the magnets. The motor performance have been evaluate by the FE analysis in the healthy and faulty mode operations: the performance fully satisfy the requirements at low and high power. The study has been completed with a detailed thermal analysis in order to calculate the temperature in the stator winding and PMs at steady-state imposing the severe duty cycle.