Design, Analysis, and Realization of a Hybrid-Excited Magnetic Gear During Overload

This article proposes a novel hybrid-excited magnetic gear (HEMG) with eccentric magnet structure. The novel HEMG has a higher electromagnetic torque when compared to its conventional counterpart. This study looks into the magnetic field of coaxial magnetic gear during overload, and investigates the cause of demagnetization of permanent magnets (PMs) on rotor. The PMs are attached to the inner and outer rotor; PMs of inner rotor are eccentric structure and magnetized along the radial direction, PMs of outer rotor are the radial magnetized, and the outer rotor yoke is slotted and injected with current. The proposed HEMG topology with 4 inner and 23 outer pole pairs is established; the corresponding magnetic flux density distributions, electromagnetic torque, and torque ripples are assessed and verified by finite element analysis. Finally, the HEMG is built and tested; the test results show that its transmission efficiency is up to 92.6%, and the effective length of the prototype corresponds to the torque density that is 135.15 kN center dot m/m(3).