A Novel Coaxial Magnetic Gear and Its Integration With Permanent-Magnet Brushless Motor

A magnetic geared machine (MGM) is believed to be a promising candidate for high-torque direct-drive application. One of the key issues for developing MGMs is how to resolve the contradiction between the good performance and the complex structure. This paper aims at proposing a novel coaxial magnetic gear (CMG), which will not increase the mechanical complexity after integration with a permanent magnet (PM) brushless machine. The prominent feature of the proposed CMG is the introduction of the stator with modulating teeth, which function as the same as the modulating pole-pieces in the conventional CMG. The integrated MGM can then be achieved by inserting the armature windings into the stator slots. The configuration, harmonic analysis, and torque capability of the proposed CMG are compared with the conventional CMG. The operating principle and electromagnetic performance of the proposed MGM are investigated by dividing it into one vernier PM machine, one PM brushless machine and one proposed CMG. The results show that the developed integrated MGM exhibits good torque capability and power factor.