This paper presents the design, modeling, bench experiments, and road tests for a retrofit regenerative shock absorber based on a permanent magnetic generator and a rack-pinion mechanism for the purposes of energy harvesting and vibration damping. Results show that variable damping coefficients and the asymmetric feature in jounce and rebound motions are achieved by controlling the electrical load of the shock absorber. Improved efficiency and reliability are achieved by utilizing a roller to guide the rack and preload on the gear transmission to reduce backlash and friction. A peak power of 68 W and average power of 19 W are attained from one prototype shock absorber when the vehicle is driven at 48 km/h (30 mi/h) on a fairly smooth campus road.

Electromagnetic Energy-Harvesting Shock Absorbers: Design, Modeling, and Road Tests

Nowadays, harvesting energy from vibration is one of the most promising technologies. However, the majority of current researches obtain 10 µW to 100 mW power, which has only limited applications in self-powered wireless sensors and low-power electronics. In fact, the vibrations in some situations can be very large, for example, the vibrations of tall buildings, long bridges, vehicle systems, railroads, ocean waves, and even human motions. With the global concern on energy and environmental issues, energy harvesting from large-scale vibrations is more attractive and becomes a research frontier. This article is to provide a timely and comprehensive review of the state-of-the-art on the large-scale vibration energy harvesting, ranging from 1 W to 100 kW or more. Subtopics include energy assessment from large vibrations, piezoelectric materials and electromagnetic transducers, motion transmission and magnification mechanisms, power electronics, and vibration control. The relevant applications discussed in th...

Large-scale vibration energy harvesting

This paper offers motivations for an electromagnetic active suspension system that provides both additional stability and maneuverability by performing active roll and pitch control during cornering and braking, as well as eliminating road irregularities, hence increasing both vehicle and passenger safety and drive comfort. Various technologies are compared with the proposed electromagnetic suspension system that uses a tubular permanent-magnet actuator (TPMA) with a passive spring. Based on on-road measurements and results from the literature, several specifications for the design of an electromagnetic suspension system are derived. The measured on-road movement of the passive suspension system is reproduced by electromagnetic actuation on a quarter car setup, proving the dynamic capabilities of an electromagnetic suspension system.

Active Electromagnetic Suspension System for Improved Vehicle Dynamics

Energy-harvesting shock absorbers are able to recover the energy otherwise dissipated in the suspension vibration while simultaneously suppressing the vibration induced by road roughness. They can work as a controllable damper as well as an energy generator. An innovative design of regenerative shock absorbers is proposed in this paper, with the advantage of significantly improving the energy harvesting efficiency and reducing the impact forces caused by oscillation. The key component is a unique motion mechanism, which we called ?mechanical motion rectifier (MMR)?, to convert the oscillatory vibration into unidirectional rotation of the generator. An implementation of a MMR-based harvester with high compactness is introduced and prototyped. A dynamic model is created to analyze the general properties of the motion rectifier by making an analogy between mechanical systems and electrical circuits. The model is capable of analyzing electrical and mechanical components at the same time. Both simulation and experiments are carried out to verify the modeling and the advantages. The prototype achieved over 60% efficiency at high frequency, much better than conventional regenerative shock absorbers in oscillatory motion. Furthermore, road tests are done to demonstrate the feasibility of the MMR shock absorber, in which more than 15 Watts of electricity is harvested while driving at 15?mph on a smooth paved road. The MMR-based design can also be used for other applications of vibration energy harvesting, such as from tall buildings or long bridges.

https://iopscience.iop.org/article/10.1088/0964-1726/22/2/025008/pdf

Energy-harvesting shock absorber with a mechanical motion rectifier

Significant improvements in automobile suspension performance are achieved by active systems. However, current active suspension systems are too expensive and complex. Developments occurring in power electronics, permanent magnet materials, and microelectronic systems justifies analysis of the possibility of implementing electromagnetic actuators in order to improve the performance of automobile suspension systems without excessively increasing complexity and cost. In this paper, the layouts of hydraulic and electromagnetic active suspensions are compared. The actuator requirements are calculated, and some experimental results proving that electromagnetic suspension could become a reality in the future are shown.

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Permanent-magnets linear actuators applicability in automobile active suspensions

The suspension systems currently in use can be classified as passive, semi-active and active. The passive suspension systems are the most commonly used due to their low price and high reliability. However, this system can not assure the desired performance from a modern suspension system. An important improvement of the suspension performance is achieved by active systems. Nevertheless, they are only used in a very reduced number of automobile models because they are expensive and complex. Another disadvantage of active systems is the relatively high energy consumption. The use of electromagnetic linear actuators is an alternative for the implementation of active suspensions. Moreover, this solution has the advantage of suspension energy recovery. In spite of the materials development, the electromagnetic actuators are still expensive to produce. In this paper a hybrid suspension system is proposed which combines the simplicity of the passive dampers with the performance of an electromagnetic active suspension. With a passive damper, it is possible to keep the performance of the active suspension, but using a smaller electromagnetic actuator.

/pdf/electromagnetic-hybrid-active-passive-vehicle-suspension-n8uoyqdpv1.pdf

F. Pina da Silva

Papers

Permanent-magnets linear actuators applicability in automobile active suspensions

Electromagnetic hybrid active-passive vehicle suspension system