Evaluation of Experimental Result and Utility of Flux Modulated Type Magnetic Gear

Optimal Design of Permanent Magnet Motor with Magnetic Gear and Prototype Verification

“…Nd-Fe-B bond magnets were also used as the multipole outside permanent magnets where eddy current loss readily occurs. Since Nd-Fe-B bond magnets have an electrical resistance two orders of magnitude greater than sintered magnets, the eddy current loss can be greatly reduced [12]. On the other hand, the residual flux density of a bonded magnet is 0.83 T to 0.90 T, which is 30% to 40% lower than that of an Nd-Fe-B sintered magnet, suggesting the possibility of a drop in torque.…”

“…(6) and shown by Fig. We also know that the magnetic flux density in the yoke on the multipole side varies significantly depending on its circumferential position, and that the eddy current loss occurs more readily [12]. Furthermore, a multilayered configuration can be avoided and heat dissipation to the housing can be improved by fixing the outer magnets.…”

“…5, we see that the highest gear ratio is obtained by using the inner rotor, with its small pole pair number, as the input and the pole piece, with a large number of magnetic poles, as the output. Since Nd-Fe-B bond magnets have an electrical resistance two orders of magnitude greater than sintered magnets, the eddy current loss can be greatly reduced [12]. Therefore, in this paper, we performed design by fixing the outer magnets and using the inner magnets as the input rotor and the pole piece as the output rotor.…”

“…For the magnetic gear described above, an asynchronous harmonic flux is known to flow to the magnets and the pole piece used for flux modulation, and eddy current loss is known to occur. Methods of reducing this effect have been proposed [6,7,12]. We also know that the magnetic flux density in the yoke on the multipole side varies significantly depending on its circumferential position, and that the eddy current loss occurs more readily [12].…”

“…Methods of reducing this effect have been proposed [6,7,12]. We also know that the magnetic flux density in the yoke on the multipole side varies significantly depending on its circumferential position, and that the eddy current loss occurs more readily [12]. Thus, in the design described here, we attempted to reduce the eddy current loss by using an Nd-Fe-B sintered magnet with a residual flux density of 1.4 T for the permanent magnet of the inner rotor, with a small number of poles, divided into five parts in the axial direction, and attached segmented magnets with parallel magnetization to each pole in the circumferential direction.…”