Novel Variable-Field Motor with a Three-Dimensional Magnetic Circuit

Abstract

We propose a novel variable-field motor with toroidal windings to achieve both miniaturization and high efficiency. The proposed motor is characterized by a structure that uses a three-dimensional (3D) magnetic flux to increase the number of torque-generation faces. The 3D structure has prevented an increase of the motor volume due to the addition of the variable field. We investigated the principle of variable field by finite element analyses and experiments. We verified that the induced voltage and the torque can be changed by changing the direct current in the field-excitation winding. Moreover, the efficiency can be improved by changing the direct current.