HYBRID STEPPER MOTOR HAVING OPTIMIZED TORQUE DENSITY

摘要

A hybrid stepper motor having optimized torque per unit volume or 'torque density' comprises a stator having an outer diameter and an inner diameter, and a rotor rotatably position within the stator inner diameter and being drivably coupled to a shaft. The rotor is of the permanent magnet type having at least one permanent magnet positioned on the shaft, and includes two rotor segments coupled on either end of the permanent magnet. The rotor segments each have a length which is calculated to optimize the torque density of the motor. The calculated optimization of the rotor segment length is accomplished as a function of the stator inner diameter to stator outer diameter ratio. The optimization of the rotor segment lengths allows for a range of values for a given stator inner diameter to outer diameter ratio as defined by a maximum length and a minimum length equation.