Double-Rotor Induction Motor

The double-rotor induction motor differs from a drag-cup motor in that the rotor is closed at both ends, necessitating the pivoting of the core inside the rotor. Since the core can carry current and is free to rotate, its characteristics affect the speed-torque characteristics of the rotor. The analysis of such a motor, including spatial harnonics, is outlined and it is shown that, in general, the core reduces the torque-to-inertia ratio of the rotor and that a low-loss core is necessary for good performance.