MAGNETORHEOLOGICAL DAMPERS WITH HYBRID MAGNETIC CIRCUITS

Author(s):  
HOLGER BÖSE ◽  
JOHANNES EHRLICH
2012 ◽  
Vol 23 (9) ◽  
pp. 979-987 ◽  
Author(s):  
Holger Böse ◽  
Johannes Ehrlich

Novel concepts for the magnetic circuit in magnetorheological dampers have been proven. In contrast to the established magnetic circuits where the magnetic field for the control of the magnetorheological fluid is generated by the coil of an electromagnet, hybrid magnetic circuits consisting of at least one permanent or hard magnet and an electromagnet are used in the new approaches. Three different technical configurations are distinguished: (1) The electromagnet is combined with two permanent magnets, whose magnetization cannot be modified even by strong magnetic fields of the electromagnet. The main advantage is the improved fail-safe behavior of the damper in case of a power failure. (2) The electromagnet is combined with a hard magnet, whose magnetization can be modified by the electromagnet. This configuration leads to high energy efficiency, because electric power is only required in short pulses for the switching of the hard magnet. (3) All three types of magnetic field sources, permanent, hard, and electromagnet, are combined in the magnetic circuit, which gives the highest flexibility of the magnetic field generation and the damping control at the expense of a relatively large effort. Demonstrators for magnetorheological dampers with all three magnetic circuits were constructed and their performances were tested. The results of the investigations are described in this paper.


2012 ◽  
Vol 77 ◽  
pp. 86-95
Author(s):  
Holger Böse ◽  
Johannes Ehrlich

Adaptive damping systems based on magnetorheological (MR) fluids allow the continuous control of vibration damping forces depending on the current conditions. In magnetorheological dampers known so far, the magnetic field for the control of the MR fluid is generated by the coil of an electromagnet. Two novel concepts for the magnetic circuit in magnetorheological dampers have been proven where hybrid magnetic circuits consisting of at least one permanent or hard magnet and an electromagnet are used. In the first concept, the electromagnet is combined with two permanent magnets, whose magnetization cannot be modified even by strong magnetic fields of the electromagnet. The main advantage of this configuration is the improved fail-safe behaviour of the damper in case of a power failure. In the second approach, the electromagnet is combined with a hard magnet, whose magnetization can be modified by the electromagnet. This configuration leads to high energy efficiency, because electric power is only required in short pulses for the switching of the hard magnet. Magnetic circuits with the combination of different magnetic field sources were designed supported by simulations of the magnetic flux distribution. Demonstration models for magnetorheological dampers with the distinguished magnetic circuits were constructed and their performances were tested. The results of the investigations are described in this contribution.


2021 ◽  
Vol 26 (2) ◽  
pp. 04020119
Author(s):  
Peng Zhou ◽  
Min Liu ◽  
Weiming Kong ◽  
Yingmei Xu ◽  
Hui Li

2020 ◽  
pp. 54-58
Author(s):  
S. M. Plotnikov

The division of the total core losses in the electrical steel of the magnetic circuit into two components – losses dueto hysteresis and eddy currents – is a serious technical problem, the solution of which will effectively design and construct electrical machines with magnetic circuits having low magnetic losses. In this regard, an important parameter is the exponent α, with which the frequency of magnetization reversal is included in the total losses in steel. Theoretically, this indicator can take values from 1 to 2. Most authors take α equal to 1.3, which corresponds to the special case when the eddy current losses are three times higher than the hysteresis losses. In fact, for modern electrical steels, the opposite is true. To refine the index α, an attempt was made to separate the total core losses on the basis that the hysteresis component is proportional to the first degree of the magnetization reversal frequency, and the eddy current component is proportional to the second degree. In the article, the calculation formulas of these components are obtained, containing the values of the total losses measured in idling experiments at two different frequencies, and the ratio of these frequencies. It is shown that the rational frequency ratio is within 1.2. Presented the graphs and expressions to determine the exponent α depending on the measured no-load losses and the frequency of magnetization reversal.


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