Browsing by Author "HSIAO, FZ"

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AN INVESTIGATION OF THE CHARACTERISTICS OF ELECTROMAGNETIC BEARINGS USING THE FINITE-ELEMENT METHOD
(1994-10-01)
HSIAO, FZ
;
LEE, AC
;
交大名義發表
;
機械工程學系
;
National Chiao Tung University
The load capacity of EMBs with a restricted air gap is usually small in comparison with that of traditional ball bearings. One possible way to overcome this limitation is to increase the operation field strength of EMBs; however, this approach unavoidably involves nonlinear characteristics of EMBs. This paper investigates the nonlinear behavior of two commonly used types of EMBs by using the finite element method, in which the nonlinear relation of the B-H curve, the flux leakage, and the fringing effect are taken into account. The behavior of the EMBs under different bias currents and gap lengths is investigated, as are the effects of geometric parameters on the bearing characteristics. The results of the paper provide a useful guide for designing EMBs when using their nonlinear characteristics.
ANALYSIS AND TESTING OF MAGNETIC BEARING WITH PERMANENT-MAGNETS FOR BIAS
(1994-12-01)
LEE, AC
;
HSIAO, FZ
;
KO, D
;
交大名義發表
;
機械工程學系
Active magnetic bearings constructed with electromagnets only are usually bulky and power-consuming This shortcoming can be remedied by adopting permanent magnets as the source of bias flux. Satisfactory results achieved by using rare-earth permanent magnets substantiate the feasibility of using permanent magnet bias in magnetic bearings. In this paper, an analytic model for permanent-magnet-biased magnetic bearings is presented. The static characteristics of a prototype are tested and compared with values estimated using this model. Manufacturing the prototype and subsequent testing offer some technological information which is important for future improvements.
PERFORMANCE LIMITS OF PERMANENT-MAGNET-BIASED MAGNETIC BEARINGS
(1994-12-01)
LEE, AC
;
HSIAO, FZ
;
KO, D
;
交大名義發表
;
機械工程學系
An active magnetic bearing with electromagnets only is unavoidably bulky and power-consuming. These shortcomings can be remedied by using permanent magnets as the source of bias flux. Unlike the hybrid magnetic bearings with the same flux path for both permanent magnets and electromagnets, so-called coplanar PEMBs, a noncoplanar PEMB with permanent magnets located between two sets of electromagnets, which are placed around the periphery of the shaft, cannot be regarded as equivalent to a pure electromagnet magnetic bearing. This paper analyzes the performance limits, such as maximum static bearing force, force slew rate, displacement sensitivity, and dynamic load capacity, of the non-coplanar PEMBs. We also campare the characteristics of this type of magnetic bearing to the co-plane PEMBs and point out their differences. Investigation of these performance limits enable better utilization of permanent-magnet-biased magnetic bearings and offer useful guidelines for the design of this type of magnetic bearing.