The design and construction of a wide speed range novel brushless DC motor

The paper describes a novel brushless DC motor of the interior magnet type which uses radial quadrature axis flux barriers. The purpose of these is to reduce the armature flux, particularly when it is cross magnetising and thus reduce the saturation in the teeth of the machine. Comparisons are drawn between the new machine and an equivalent conventional version using both finite element analysis and the results of practical standstill tests. It is shown that the torque performance of the machines is about the same but the tooth densities are considerably reduced in the machine with barriers