Performances of a new brushless half-speed synchronous motor with q-axis damper winding driven by VSI

A new brushless self-excited half-speed synchronous motor combined with a voltage source transistor inverter (VSI) is presented. This motor eliminates the brush, slip ring, and DC-exciter for environmental reasons and for minimization of maintenance requirements. It is well known that a wound-rotor-type induction motor with a short-circuited single-phase rotor winding runs at near half synchronous speed, according to the Gorges phenomenon. Superimposing a stationary magnetic field on the stator winding compels the motor to run at exactly half synchronous speed, i.e., s=0.5. In this motor, the difference between direct and quadrature-axis reluctances produces a torque like that in a reluctance motor, and the effective q-axis reactance can be decreased by inserting a q-axis squirrel-cage damper winding on the salient poles. The proposed practical rotor configuration of the motor is illustrated. The motor characteristics, parallel operation system, transient response at a sudden change of load, and variable-speed drive system are described.<>