The analysis of fields and torques in spherical induction motors

The advent of robotics and automated manufacturing processes has brought about an urgent need for novel electromechanical transducers with unusual design and performance characteristics. Operating flexibility, ruggedness, size, force-to-weight ratio, and robust control capabilities are design attributes which place a heavy burden on conventional machines used for manipulation purposes. The spherical induction motor is an electromechanical drive which holds considerable promise in these application areas. A general analysis of both the fields and resultant forces generic to the spherical induction motor is presented. The analysis properly accounts for the diffusion of the magnetic field with changing frequency and motor speed. To aid in the prediction and conceptualization of the torque and commensurate motor losses, normalized plots of these parameters are given for various limiting values of skin depth ratio to conductor thickness. Results indicate that the device is capable of continuous speed control and efficient torque production.