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Description
Traditional heteropolar radial hybrid magnetic bearing (HRHMB) with eight poles has been widely applied in high-speed applications, such as flywheel energy storage system (FESS), because of its simple structure, low power loss, and high critical speed. However, this topology suffers large displacement stiffness, magnetic coupling, and non-negligible rotor iron loss. To overcome these drawbacks, one novel HRHMB with double-layer stator is proposed in this paper. In this structure, permanent magnets (PMs) are located between X and Y stator teeth, and X and Y stators are separated by PMs and nonmagnetic ring. The bias-flux is closed through PMs, X and Y stator teeth, air gap and rotor and the control-flux is closed through X/Y stator, air gap and rotor respectively. Compared with the conventional HRHMB, there are only four poles with active control coils, which means smaller displacement stiffness, less fluctuation of magnetic field and lower rotor core loss in the proposed novel HRHMB. Besides, the control of X and Y dimension in the new structure are independent of each other due to the effect of nonmagnetic ring, which decreases the control magnetic field coupling of the two dimensions significantly. This paper is organized as follows. Firstly, the topology and working principle for the new HRHMB are introduced in details. Then, the mathematical expressions are derived based on equivalent magnetic circuit model, including displacement stiffness, current stiffness and load capacity. Finally, one three-dimension finite element analysis (3-D FEA) model is built based on the given specifications to further analyze its suspension performance indexes, magnetic coupling, power losses, etc. Comprehensive investigations indicate the novel HRHMB has small displacement stiffness, good decoupling control and low rotor iron loss, which makes it more suitable to high-speed FESS. More details will be given in the final paper.
| Submitters Country | China |
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