Torque Characteristic of a Novel Tiered Type Permanent Magnet Spherical Motor

This article mainly investigates the torque characteristic of a novel tiered type permanent magnet spherical motor (T-PMSpM), which has the advantage of relatively larger torque ability compared with most existing spherical motors. The investigated T-PMSpM is capable of continuously rotating while the rotating shaft can tilt in all directions. Therefore, both the rotating torque and tilting torque need to be studied. Considering that the rotating principle is similar to the conventional permanent magnet synchronous motors, more attention is being paid to the tilting performance since it also decides the tilting range of the T-PMSpM. First, the key factors that significantly influence the tilting torque are found out based on the analytical expression of the tilting torque. Then, these key factors are analyzed aiming at expanding the tilting range as well as the magnitude of the tilting torque. Finally, the rotating torque is obtained and analyzed based on the above-optimized structure. The three-dimensional finite-element method is adopted for accurate calculation. A prototype motor of the T-PMSpM has been manufactured, and an experimental procedure is designed to measure the output torque for verification.