Abstract
Direct drive motors are used as actuators in numerous applications in which they must rotate at low speeds with high torque and low torque ripple. Recently, various types of vernier motor have been developed. The HB type vernier motor is one of them. The structure of rotor is the same as HB type stepping motor. Our model of HB type vernier motor has a winding as field system in the rotor, but stator has three-phase windings.
Relationship between S, R and P is S ± P/2=R/2, where S, R and P are the numbers of stator and rotor slots and the number of poles. The rotor of the vernier motor moves at a sub-multiple of the angular velocity of the stator mmf. The multiplying factor is P/R.
As a result of analysis, the voltage equation on the γ-δ axis of HB type vernier motor is equal to general synchronous machine. The tests were performed on the trial motor. The calculated pull-out torque agreed well with the measured values. Our model of HB type vernier motor is equivalent with the PM type vernier motor which has permanent magnets in the rotor. The result of this analysis is useful for the design of both types of vernier motor.
