The Principle and Fundamental Characteristics of Brushless Three-Phase Synchronous Induction Motor with Two Stators

Brushless three-phase synchronous motor involving a rotating AC exciter on the same shaft as the motor and with the windings linked through a shaft-mounted rectifier is widely put to practical use as medium and large capacity machines. However, the motor needs to fit with damping windings for self-starting outside of the field winding in the rotor and needs to equip discharge resistance with complex electronic device to dispose of electromagnetic force induced in the field winding at starting. Therefore, the rotor structure is very complex, and there are disadvantages especially for robust and high reliability required generally to motor.In order to solve this problem existing in traditional motor, authors proposed a brushless three-phase synchronous induction motor with two stators and one wound rotor. This problem is solved because the proposed motor is two stators structure: The rotor winding operates as the secondary winding of induction motor at starting and as the field winding at synchronous operation.The motor can self-start as a wound-rotor induction motor without external secondary resistance. Therefore, discharge resistance is not necessary; the starting equipment is very simple and the rotor structure is robust. It is possible to start with high torque.In this paper, the basic constitution of the proposed motor and the principles of operation are described in detail. The experimental results at starting and pulling into synchronism are shown for confirming the principles of operation and the experimental and the numerical results of the starting characteristics, the load ones, the generating ones are shown: the practical use of the proposed motor is confirmed.