Benefits of Nd-Fe-B magnet in brushless DC motor design for aircraft applications

Aircraft and defence applications require extremely compact designs which have the benefits of saving weight and space. These aspects demand motors of very high output power to weight ratio and reasonable high efficiency. There has seen a significant number of brushless DC motors being developed for the above applications. The author looks at the use of neodymium-iron-boron magnet in the design of brushless DC motors. The effect of high energy product of NdFeB is examined in relation to performance and frame size. Performance results of the motor with NdFeB for a typical practical application are presented. Design ideas relating to rotor geometries for a wide range of fan applications are described and shown to have significant improvement in both power to weight ratio and efficiency. Examples of practical drives are also presented