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Design of axial active magnetic bearing with high load capacity for low pressure centrifugal chiller.

Number: 1225

Author(s) : CHIANG S. Y., CHEN C. Y., HUNG K. S.

Summary

Comparing with medium-pressure chiller, low-pressure chiller usually has better system efficiency. At the same capacity, however, the radius of impellers in low-pressure compressor must be increased due to using higher specific volume refrigerants. In general, it means this kind of chillers have heavier structure and results in larger chiller room occupancy. Larger radius of impeller not only increases manufacturing cost but also enforces the axial bearing force during rated operation condition. Especially for active magnetic bearing (AMB) application, the load capacity of axial bearing force is one of the critical issues that leads to cost reduction or not. In this research, we developed an axial AMB using permanent magnets to provide the basic axial force of the thrust disk. This design allows the impeller can support larger axial load but is dangerous for output force reversed. Therefore, our design is particularly suitable for unidirectional axial force condition due to high pressure ratio applications. In order to improvement the controllability of AMB system, we designed a magnetic barrier zone in main flux path of permanent magnets to constrain its magnetic flux to make the flux of current coils and the flux of magnets be decoupled. We used static magnetic field analysis to deduce the analytical model of this axial AMB, and verified our idea through hardware implementation. In our experiments, we demonstrated that the axial AMB can work normally with linear quadratic regulator (LQR) controller, and the control current decreases linearly as the axial support weight increasing. This technology can reduce the axial bearing control current of the chiller. Especially for rated operating conditions, it can maintain a small current consumption and improve system performance.

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  • Original title: Design of axial active magnetic bearing with high load capacity for low pressure centrifugal chiller.
  • Record ID : 30033585
  • Languages: English
  • Subject: Technology
  • Source: 2024 Purdue Conferences. 27th International Compressor Engineering Conference at Purdue.
  • Publication date: 2024/07/18

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