Analysis of Novel Brushless DC Motors Made of Soft Magnetic Composite Core

The soft magnetic composite material has merits of the low eddy current loss and the flexible machine design and assembly. This paper develops new brushless DC motors made of this material. The shape of the developed motor is similar to a hybrid type stepping motor, which utilizes three-dimensional isotropic ferromagnetic behavior, and the motor has hollows in the stator main teeth in order to reduce the copper loss and the motor size. This paper clarifies the steady state characteristics of the motors using the three-dimensional finite element analysis. The motor efficiency becomes larger than that of the conventional laminated core, when the rotating speed is high, or if the motor size becomes large.