Novel Adaptive Damping Systems Based on Magnetorheological Fluids

2012 ◽  
Vol 77 ◽  
pp. 86-95
Author(s):  
Holger Böse ◽  
Johannes Ehrlich
Keyword(s):  
Magnetic Field ◽  
Permanent Magnets ◽  
High Energy ◽  
Continuous Control ◽  
Magnetorheological Dampers ◽  
Short Pulses ◽  
Magnetic Circuits ◽  
Hard Magnet ◽  
Fail Safe ◽  
Damping Systems

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.

Magnetorheological dampers with various designs of hybrid magnetic circuits

2012 ◽  
Vol 23 (9) ◽  
pp. 979-987 ◽  
Author(s):  
Holger Böse ◽  
Johannes Ehrlich
Keyword(s):  
Magnetic Field ◽  
Permanent Magnets ◽  
Magnetic Circuit ◽  
High Energy ◽  
Magnetorheological Dampers ◽  
Magnetic Field Generation ◽  
Magnetic Circuits ◽  
Hard Magnet ◽  
Large Effort ◽  
The Magnetic Field

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.

scholarly journals Efficiency estimation for permanent magnets of synchronous wind generators

2014 ◽  
Vol 51 (1) ◽  
pp. 21-31 ◽  
Author(s):  
A. Serebryakov ◽  
N. Levin ◽  
A. Sokolov ◽  
E. Kamolins
Keyword(s):  
Magnetic Field ◽  
Permanent Magnets ◽  
Direct Action ◽  
High Energy ◽  
Electrical Machine ◽  
Maintenance Costs ◽  
Wind Generators ◽  
Efficiency Estimation ◽  
Indirect Action ◽  
Proper Orientation

Abstract Application of wind generators opens wide possibilities for raising the efficiency of low- and medium-power wind generators (WGs). The mass of generators in the proposed version is smaller, their reliability higher, while maintenance costs are lower. At the same time, the use of high-energy permanent magnets in generators of enhanced power comes up against some obstacles, which can be overcome through proper orientation of magnetization at creation of a magnetic field in the airgap of electrical machine. In this regard, it might be preferable to use magnets with indirect action on the airgap instead of those with direct action. A convincing example of the former variant is a generator with tangentially oriented magnetization of permanent magnets. In the work, an attempt is done to prove the advantages of such installation in modern low- and medium-power WGs

scholarly journals Efficient Toughening of Short-Fiber Composites Using Weak Magnetic Fields

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2415
Author(s):  
Omri Goldberg ◽  
Israel Greenfeld ◽  
Hanoch Daniel Wagner
Keyword(s):  
Magnetic Field ◽  
Fracture Toughness ◽  
Magnetic Fields ◽  
Permanent Magnets ◽  
Glass Fibers ◽  
High Energy ◽  
Short Fiber ◽  
Local Concentration ◽  
Weak Magnetic Fields ◽  
Energy Dissipated

Short fibers may serve as toughening agents of composite materials because of the high energy dissipated during fracture, associated with numerous fiber pullouts. An ongoing challenge is to improve their toughness even further, by directing and concentrating fibers near highly stressed structural regions. Weak magnetic fields are utilized to increase the fracture toughness of an epoxy matrix reinforced by short magnetized glass fibers by directing and concentrating fibers near highly stressed structural regions. The orientation and local concentration of the fibers are controlled by the vector components of the magnetic field, and by the gradient in field intensity, respectively. Optimized fracture toughness was achieved by using two pairs of permanent magnets, combining enhanced concentration of fibers in the crack-tip vicinity with alignment of the fibers along the load direction. This optimized value was well above the reference fracture-toughness measured for composites with the same filler content in the absence of a magnetic field, as well as above the value achieved by exploiting unidirectional alignment, without fiber translation, using a solenoid. The method suggested in this study—localized reinforcement using magnetic translation of fillers through the formation of magnetic gradients—enables efficient and controllable improvement in the composite’s overall resistance to fracture, without the involvement of additional phases or material.

scholarly journals Design Optimization of Interior Double-Radial Synthetic Magnetic Field Permanent Magnet Generator for Electric Vehicle

2018 ◽  
Vol 202 ◽  
pp. 02001
Author(s):  
Shilun Ma ◽  
Xueyi Zhang ◽  
Wenjin Hu
Keyword(s):  
Magnetic Field ◽  
Finite Element ◽  
Permanent Magnet ◽  
Permanent Magnets ◽  
Cogging Torque ◽  
Magnetic Circuits ◽  
Element Simulation ◽  
Before And After ◽  
Optimization Parameters ◽  
High Space

The Interior double-radial permanent magnent generator (IDRPMG) which composed by two groups of rectangular permanent magnets to provide parallel magnetic circuits of the rator and the sator core with less eddy current loss, low hormonic content and low cogging torque of the stator with fractional slot winding is developed. It has the advantages of remarkable magnetism gathering effect, strong magnetic field intensity and high space utilization. Combining Taguchi method and finite element method, the relevant parameters of the permanent magnet size and the angle between the first and second rectangle permanent magnets in rotor are optimized to get better the distortion rate of output voltage waveform, lower cogging torque and higer peak value of airgap flux density. Then finite element simulation is taken for the best optimization scheme through comparative analysis of the machine by before and after optimization. It showed that each performance index is improved after optimization. Finally, the prototype is manufactured, according to the optimization parameters and some experiments are conducted, which results verify the analys is preview well.

scholarly journals Design of a New 1D Halbach Magnet Array with Good Sinusoidal Magnetic Field by Analyzing the Curved Surface

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2522
Author(s):  
Guangdou Liu ◽  
Shiqin Hou ◽  
Xingping Xu ◽  
Wensheng Xiao
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Permanent Magnet ◽  
Flux Density ◽  
Permanent Magnets ◽  
Air Gap ◽  
Curved Surface ◽  
Magnetic Flux Density ◽  
Sinusoidal Magnetic Field ◽  
The Magnetic Field

In the linear and planar motors, the 1D Halbach magnet array is extensively used. The sinusoidal property of the magnetic field deteriorates by analyzing the magnetic field at a small air gap. Therefore, a new 1D Halbach magnet array is proposed, in which the permanent magnet with a curved surface is applied. Based on the superposition of principle and Fourier series, the magnetic flux density distribution is derived. The optimized curved surface is obtained and fitted by a polynomial. The sinusoidal magnetic field is verified by comparing it with the magnetic flux density of the finite element model. Through the analysis of different dimensions of the permanent magnet array, the optimization result has good applicability. The force ripple can be significantly reduced by the new magnet array. The effect on the mass and air gap is investigated compared with a conventional magnet array with rectangular permanent magnets. In conclusion, the new magnet array design has the scalability to be extended to various sizes of motor and is especially suitable for small air gap applications.

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