A Brushless Three-Phase Synchronous Motor Using an Armature Winding Both as Load and DC Exciting Wingdings

Abstract

This paper presents a new brushless three-phase synchronous motor which has no exciter. The technique applied to the motor gives an effective way for conventional brushless synchronous motors to simplify the system configuration. The stator of the motor is equipped with a double-star connected armature winding which has two neutral points. The rotor is a cylindrical one, which is equipped with a two-phase field winding. The field winding is connected with shaft-mounted rectifiers. A DC voitage is applied to the two neutral points of the armature winding to obtain the rotor excitation when the motor is operated at synchronous speed. At that time, the armature winding acts as a stator DC exciting winding while acting as a load winding. In this paper the principle and characteristics of the motor are described, and the experimental results are shown. It is confirmed that with a 2-kW experimental machine, the proposed motor has good performance. For example, by adjusting the stator DC current, this motor's power factor can be easily controlled within a wide range.