A Study on Rotor Design of Consequent-Pole Permanent Magnet Machines

Permanent magnet (PM) machines generally employ rare-earth PMs. The rare-earth PMs increase the manufacturing cost of PM machines due to their high material cost. To reduce the manufacturing cost of PM machines, this paper studies a consequent-pole configuration. Consequent-pole PM machines have poles with magnets and poles composed of iron-cores. The rotor design can adjust the air-gap flux density distribution. This improves the average torque and reduces the volume of PMs simultaneously. In this paper, the rotor of a consequent-pole surface-mounted PM machine is designed to reduce the volume of PMs. The characteristics are investigated for the rotor structure through a theoretical calculation and a finite-element method analysis. These results show that the consequent-pole configuration can reduce the volume of PMs in comparison with a conventional one.