Comparison between coreless and slotless kinds of dual rotor discs hysteresis motors

Hysteresis motors have some distinct advantages such as constant speed and torque, noiseless operation, robust structure, and low-starting current in comparison with other synchronous motors. The main general defects of the hysteresis machines are low efficiency and relatively low-torque density. In this study, two previously proposed structures for the hysteresis motors named ‘coreless dual rotor discs hysteresis motor’ and ‘slotless dual rotor discs hysteresis motor’ are compared with each other and with other conventional hysteresis motors from different aspects. Rectifying the iron loss in the coreless type, especially in high-speed applications, and rotor parasitic loss in the slotless type are the most important advantages of these structures. Relative ease of manufacturing process, low production cost, and extendable torque (by multi stack structure) are other significant advantages of these motors. On the basis of two derived optimal designs for the motors, the performances of the motors are compared in different supply voltages.