Study On The Energy Harvesting And Dynamic Performances Of The Magnetic Suspension For Passenger Vehicles

With the encouragement of the state and related enterprises,new energy vehicles have been vigorously developed,in which the use of electric vehicles is more and more.However,the endurance of electric vehicles is still valued.Therefore,it is urgent to actively explore new fields,research new structures and develop new functions.At present,the solution of endurance ability is mainly reflected in overcoming the battery problem,harvesting the vibration energy,applying self-powered technology.In the process of vehicle driving,the suspension system can produce vibration,which makes the two ends of the suspension move mutually.The damper is used to reduce the impact of the road and convert the mechanical energy of the suspension into heat energy.The heat energy generated by the damper is difficult to be harvested,which leads to the waste of vibration energy,and how to harvest and reuse the dissipated energy has become a hot topic in the field of energy harvesting.In addition,vehicle safety should not be ignored when a new suspension structure is designed.When the suspension structure is designed in this paper,the occupation of chassis space,reducing friction loss,reducing structural complexity,sufficient safety and providing active power need to be considered.Therefore,based on the working principle of the voice coil motor,a novel magnetic suspension for passenger vehicles with high safety,high integration and low cost is proposed based on the structure of Mc Pherson passive suspension.The energy harvester of the magnetic suspension is designed according to Faraday law of electromagnetic induction and the working principle of the voice coil motor.At the same time,the energy harvester is embedded in the traditional passive suspension,which is connected with the upper and lower ends of the suspension,respectively,and forms a parallel relationship with the passive suspension.When the vehicle is driving on the road,the vehicle’s suspension system will be vibrated due to the uneven road.The energy-harvesting suspension can convert part of the vibration energy of the suspension system into available electric energy to power for the onboard electronic equipment.Therefore,the magnetic suspension has the safety of traditional passive suspension and combines with self-powered technology to achieve the purpose of harvesting and utilizing electric energy.In this paper,firstly,the structure design and the modeling of the magnetic field and suspension system for the novel magnetic suspension are carried out based on the research status and shortcomings of the existing energy-harvesting suspension;The energy harvesting characteristics and the energy harvesting application of the magnetic suspension are analyzed and investigated,respectively;The coupling characteristics between the energy harvesting characteristics and the dynamic characteristics of the magnetic suspension are studied;The simulation analysis of a real vehicle with the magnetic suspension is carried out.The specific research contents of this paper include the following aspects:(1)An energy harvester is designed,and combined with the structure of the passive suspension,the magnetic suspension for the vehicles is proposed and designed,and the installation method between the energy harvester and passive suspension is investigated;The magnetic induction line of the energy harvester is analyzed by using the Maxwell analysis software,according to the analysis results,the magnetic field division method is used in the air gap magnetic field.The mathematical models of the magnetic field for the energy harvester and the two degrees of freedom quarter-vehicle are established based on the magnetic equivalent circuit method;An experimental prototype is fabricated,and a suspension system experimental setup is built to investigate the energy harvesting mechanism of the magnetic suspension.Finally,the accuracy of the magnetic field model is verified by comparing the numerical and measurement results of the magnetic induction intensity in the air gap.(2)According to the mathematical model of the suspension system,the energy harvesting model is solved,and the factors affecting the energy harvesting characteristics are obtained;In the aspect of the device structure,the influences of the structure parameters of stator and mover on energy harvesting are investigated,in which the stator includes magnet,iron ring and air gap,and the mover includes coil turns and wire diameter;In the aspect of the suspension system,the influences of suspension system parameters and external load resistance on energy harvesting is investigated;Through the collected voltage data,the effect of various load resistances on the energy harvesting is verified by experiments.(3)The input excitations mainly include impact excitation,periodic excitation and random excitation,the energy harvesting characteristics of the magnetic suspension under different excitations are studied.The variable periodic excitation is variable frequency and amplitude,and the variable impact excitation and random excitation are variable amplitude;A full bridge rectifier and filter circuit is designed to investigate the output voltage changes after passing through the rectifier and filter circuit under different excitations and external load resistances;Combined with the self-powered technology,the energy harvesting application experiment is carried out,and the experiments of lighting LED and self-powered sensor are investigated and analyzed.(4)Compared with the traditional suspension system,the effects of the magnetic suspension on vehicle dynamic performances under different excitations are discussed,and the variable damping characteristics of the magnetic suspension are investigated.The harvested power,vehicle body acceleration and relative dynamic load of the tire are adopted as three performance evaluation indexes of the energy-harvesting suspension.According to the mathematical model of the 2DOF quarter-vehicle with the magnetic suspension system,the effects of the system input excitation,electromechanical coupling coefficient and external load resistance on the coupling characteristics of the magnetic suspension are studied.Finally,the experiments for the input excitation and external load resistance are carried out to verify the electromechanical coupling characteristics of the magnetic suspension.(5)The energy harvesting and dynamic characteristics of a real vehicle with magnetic suspension are investigated.The nonlinear dynamic model of a 2DOF quarter-vehicle is established,and the change of the energy harvesting and dynamic characteristics of the suspension system is solved by numerical method.The vibration response of the system is analyzed by using the time domain diagram,frequency domain diagram,phase diagram and Poincare diagram.Furthermore,the effects of excitation frequency,suspension stiffness,suspension damping and mass ratio on energy harvesting and dynamic response of the vehicle system are studied.Finally,the magnetic suspension is compared with the investigated energy-harvesting suspension and other energy harvesting methods.Finally,the research results of the paper are summarized,and the innovation of the paper is introduced.Furthermore,future research on magnetic suspension is prospected according to the existing research results.