PERFORMANCE OF HYBRID ELECTROMAGNETIC DAMPER FOR VEHICLE SUSPENSION
Authors: Mr. Ganapati Vhanamane 2 Dr. B. P. Ronge
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Suspension systems, in the automotive application context, have been designed to maintain contact between a vehicle’s tires and the road, and to isolate the frame of the vehicle from road disturbances. Dampers, or so-called shock absorbers, as the undeniable heart of suspension systems, reduce the effect of a sudden bump by smoothing out the shock. In most shock absorbers, the energy is converted into heat via viscous fluid. In hydraulic cylinders, the hydraulic fluid is heated up. In air cylinders, the hot air is emitted into the atmosphere. There are several common approaches for shock absorption, including material hysteresis, dry friction, fluid friction, compression of gas, and eddy currents.
Eddy currents are induced in a conductor either by the movement of the conductor in a static field or a change in the strength of the magnetic field. The generated eddy currents create electromagnets with magnetic fields that oppose the change in an external magnetic field, causing a repulsive force proportional to the relative velocity of the field and conductor. Consequently, the eddy current damping device acts like a viscous damper, causing the vibration energy of the moving mass to dissipate through resistive/Joule heating, generated in the conducting component. The use of the eddy current damping phenomenon is appealing, because the damper structure is simple and requires neither external power supply nor electronic devices; in addition, no fluid is involved in the damper, and the moving parts of the damper have no mechanical contact.
Applications of the eddy current damping effect in vibration suppression studies have been reported, but, to the best of the author’s knowledge, the application of the eddy current in vehicle suspension systems has not been addressed in prior publications. Chapter 3 covers the development and feasibility study of utilizing eddy current damping effect as a potential passive damping source in vehicle suspension applications.
In conventional hydraulic suspension systems, shock absorbers convert the mechanical energy of the vibration into heat energy, so this mechanical energy is dissipated (Suda et al., 1996). Segal et al. (1982) have demonstrated that roughly 200 watts of power are dissipated in an ordinary sedan traversing a poor road at 13.4 m/s; hence, suspension systems have the potential for energy regeneration. Using electromagnetic dampers (composed of electromechanical elements), the kinetic energy of vehicle body vibration can be regenerated as useful electrical energy. The electromagnetic dampers (as actuators) have the potential to be used in active suspension systems.
In this paper it is proposed to prepare a model of Permanent magnetic eddy current damper. For the advantages of non-contact, mechanical friction free, lubrication free, controllable and measurable stiffness and damping properties, Permanent magnetic damper does not require extra power supply or excitation winding, so it is energy-saving, highly efficient and greater in braking density . The design of a new permanent magnetic eddy current damper is proposed in this thesis, which can provide planar electromagnetic damping force on mangle positioning platform  and other accurate positioning systems and meet the needs of fast, accurate and stable positioning. Based on the structural design, the dissertation work suggests a model of permanent magnetic eddy current damper by using FFT analysis.