Axis-Shifted Machines with Hybrid Rotors Considering Forward and Reverse Operations

In this paper, a permanent synchronous machine with hybrid rotors is designed to increase the torque density of the machine. The hybrid rotor consists of two axially parallel parts. One provides the reluctance torque of the machine, and the other increases the permanent magnet torque of the machine. By offsetting the permanent magnet torque part of the hybrid rotor, the permanent magnet torque and reluctance torque of the machine is maximized at the same current angle so that the total electromagnetic torque is increased significantly. A slider was further added to the hybrid rotor to improve the reverse rotation torque performance. By using the slider, the electromagnetic torque in the forward operation conditions is further strengthened, and the reverse torque is also improved at all current angles. Finally, using finite element analysis, it is found that the proposed hybrid rotor structure with slides can provide better torque performances in both forward and reverse operations compared to the traditional interior rotor.