A Basic Study of a Novel Homopolar-Type Magnetic Bearing Unifying Four C-Shaped Cores for High Output and Low Loss

A magnetic bearing (MB) can suspend a rotor shaft with noncontact, so the MB has been used for high-output and high-speed machines. In general, heteropolar-type MB structure is used, because of its simple structure and low cost. However, the heteropolartype MB structure has a problem in terms of rotor iron loss caused by an alternating magnetic field on a rotor core. On the other hand, general homopolar-type MB structure has a low rotor iron loss caused by a dc magnetic field on a rotor core. However, as the general homopolar-type MB has a complicated structure and needs a large magnet for generating the bias flux, it becomes costly. Therefore, this paper discusses a novel homopolar-type MB structure unifying four C-shaped cores for high output and low iron loss. It is shown with three-dimensional finite element analysis that the novel homopolar-type MB has lower iron loss and lower cost than the general homopolar-type MB, which is known for its low iron loss.