Tribology and Materials | Volume 4 | Issue 2 | 2025 | 90-99
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https://doi.org/10.46793/tribomat.2025.011
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Power losses vs. mechanical load of an active magnetic bearing: A finite element method approach
Vasileios Menelaos Koufopanos
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Andreas Andrikopoulos,
Pantelis Nikolakopoulos
University of Patras, Patras, Greece
Abstract: Active magnetic bearings are a novel solution for supporting rotating shafts. Thanks to the electromagnets and their ability to apply forces without any mechanical contact needed, they enable frictionless rotation while eliminating wear. Although mechanical friction is absent in such an element, there are other loss mechanisms to consider, such as the ohmic losses on each electromagnet's coils, as well as the iron losses caused by the alternating magnetic field on the rotor and, occasionally, on the stator. In this paper, the effects of the bearing's length, the air gap and the bias current, both on the bearing's mechanical load capacity and on the ohmic and iron losses, are examined. A series of values for the aforementioned parameters is tested using a 2D finite element transient model, which calculates the bearing's mechanical load and iron losses, in addition to analytical calculations for the ohmic losses. Then, the control current required for a specific mechanical load is calculated for different bearing lengths and magnetic air gaps. Considering the ohmic and iron losses for each case, a value for the air gap and the bearing's length is selected to achieve the required load while the losses are minimised.
Keywords: active magnetic bearings, ohmic losses, iron losses,
mechanical load capacity, finite element method.
Received: Received: 20-10-2024, Revised: 31-01-2025, Accepted:
03-03-2025
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) license, which allows users to distribute, remix, adapt,
and build upon the material in any medium or format for non-commercial purposes only, and only so long as attribution is given to the creator.
Abstract: Active magnetic bearings are a novel solution for supporting rotating shafts. Thanks to the electromagnets and their ability to apply forces without any mechanical contact needed, they enable frictionless rotation while eliminating wear. Although mechanical friction is absent in such an element, there are other loss mechanisms to consider, such as the ohmic losses on each electromagnet's coils, as well as the iron losses caused by the alternating magnetic field on the rotor and, occasionally, on the stator. In this paper, the effects of the bearing's length, the air gap and the bias current, both on the bearing's mechanical load capacity and on the ohmic and iron losses, are examined. A series of values for the aforementioned parameters is tested using a 2D finite element transient model, which calculates the bearing's mechanical load and iron losses, in addition to analytical calculations for the ohmic losses. Then, the control current required for a specific mechanical load is calculated for different bearing lengths and magnetic air gaps. Considering the ohmic and iron losses for each case, a value for the air gap and the bearing's length is selected to achieve the required load while the losses are minimised.
Keywords: active magnetic bearings, ohmic losses, iron losses, mechanical load capacity, finite element method.
Received: Received: 20-10-2024, Revised: 31-01-2025, Accepted: 03-03-2025
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This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) license, which allows users to distribute, remix, adapt, and build upon the material in any medium or format for non-commercial purposes only, and only so long as attribution is given to the creator.