Research On Key Techniques Of Hybrid Electromagnetic Regenerative Suspension Damper

With the continuous development of electromechanical technology and automobile industry,the energy-saving and low-carbon technologies of vehicles have become the focus of current research works.In various systems of vehicles,the suspension system consumes a considerable amount of power.In conventional suspension systems,this part of the power is generally dissipated as internal energy by oil damper.On the other hand,as people’s requirements for vehicle suspension comfort and controllability become higher,some active suspensions have begun to appear in mid-to high-end models.However,the active suspension needs to input energy from outside to adjust its dynamic parameters or directly apply control force,which is followed by the high energy consumption of the vehicle suspension system.The development of a low-power,even power-generating suspension that can balance the comfort and controllability has become an important technological demand for the automobile industry.In this atmosphere,the regenerative suspension technology shows great practical application value.Among them,the electromagnetic regenerative suspension damper has advantages of less energy conversion process and quicker response than the hydraulic type,liquid-electric regenerative suspension damper,and has become a research hotspot in the vehicle suspension technology field in recent years.Aiming at some problems in the linear motor type regenerative damper,this thesis proposes a scheme to improve its energy harvesting performance and the maximum damping coefficient by using Halbach permanent magnet array as its transducing component.On this foundation,a concentrically compound damper that combines the eddy current generation structure and the electromagnetic energy harvesting device is proposed.The eddy current effect can be used to increase the specific mass damping coefficient of the damper.The dislocation rate between the two sets of concentric permanent magnet arrays can be used to extend the damping coefficient adjustable range.The main research work and innovations of the thesis are as follows:(1)The dynamic model of vehicle suspension is established.Based on the two suspension performance indexes of the acceleration transmission rate and displacement transmission rate,the effects of the system damping ratio on the comfort and controllability of the suspension is analyzed.According to the dynamic model of the vehicle suspension,the road roughness model was used to analyze and calculate the dissipated power in typical vehicle suspension under different road conditions and different vehicle speeds.The study found that the power dissipated in the suspension is proportional to the speed of the vehicle.The road roughness has a great influence on the power dissipation at the same vehicle speed.(2)Starting from the energy flow process in the suspension system,combined with electromagnetic induction law,magnetic circuit law,and mechanical vibration,a physical model of an electromagnetic energy harvesting device was established.The corresponding kinetic equations and energy conservation equations were deduced.The thesis systematically describes the mechanism of transduction and gives the design criteria of the electromagnetic transduction.Studies have found that in order to increase the energy harvesting performance,the quality constant of the induction coil of the electromagnetic energy harvesting system needs to be as large as possible.Due to the maximum allowable relative displacement between transducer components,the circuit damping and passive damping need to be able to ensure that the damper stroke does not exceed its limit.In order to improve the energy harvesting performance and broaden the damping adjustment range,the passive damping should be appropriately reduced.(3)A lumped parameter equivalent magnetic circuit model of electromagnetic energy harvesting device is proposed.On this theoretical foundation,the static magnetic field modeling and structural parameters optimization of the magnetic circuits are performed.Theoretical studies have found that the optimal permanent magnet thickness ratios for axial magnetization,radial magnetization,and Halbach permanent magnet array structures are 0.5,1,and 0.75,respectively,and the ratio of permanent magnet to coil radial ratio is 0.8,0.75,and 0.7,respectively.Under the conditions,the maximum circuit damping coefficients can be achieved.The coil winding form and rectifying circuit of the corresponding regenerative damper were designed.The lumped parameter equivalent magnetic circuit model was verified by COMSOL Multiphysics finite element software,as well as the open circuit voltages and damping performances of three types regenetaive dampers were obtained.The research shows that the optimized Halbach permanent magnet array structure is superior to the axial and radial magnetization structure in terms of output electrical performance and damping performance.(4)A concentrically compound damper that combines the eddy current generation structure and the electromagnetic energy harvesting device is proposed.Its specific mass damping coefficient can be further improved by the eddy current effect.The effects of the eddy current generation structure on the optimal structure parameters of the Halbach permanent-magnet array regenerative damper is analyzed.The study found that the introduction of the eddy current generation structure will affect the performance of the regenerative damper to a certain extent,but it has little effect on the optimal structural parameter combination of the electromagnetic energy harvester.The optimal size parameters of the eddy current generation structure are obtained by the analytical model.By defining the dislocation rate between the two sets of concentrically compound permanent magnet arrays,the influence of the dislocation rate on the circuit damping,energy harvesting performance and eddy current damping is explored.It is found that the adjustment of the dislocation rate can be used to broaden the damper damping coefficient adjustment range.(5)According to the testing requirements of the regenerative dampers,a corresponding damper test platform was built.Based on the structural parameter optimization conclusions,prototypes of the regenerative and hybrid dampers were made.For the regenerative dampers,the maximum damping coefficients of the three types magnetic circuit structure with axial magnetization,radial magnetization,and Halbach permanent magnet array are respectively limited to the same external dimensions.Their maximum damping coefficients can reach 202.6 Ns/m,209.4Ns/m and 472.8Ns/m,respectively.When the vibration excitation frequency is 5Hz and the amplitude is 10 mm,and the load impedances match the internal resistances of the regenerative dampers,the maximum available electric power of the three types of magnetic circuit structure regenerative dampers are about 0.9W,0.93 W and 2.1W,respectively.The optimized Halbach permanent magnet array structure has better energy harvesting and damping performance than the other two.For the concentrically hybrid damper prototype,the output electrical performance and eddy current damping performance with different dislocation rates were experimentally measured.The relationship between the damping range,the maximum energy harvesting power and the dislocation rate was calculated.The research shows that the maximum energy harvesting power of the hybrid damper prototype can reach 1.7W when the concentrical PM array dislocation rate is 1 under the direct excitation of a weak harmonic vibration with a frequency of 5Hz and an amplitude of 6mm.The adjustment range of the damping coefficient can be effectively widened to 500N?s/m to 1270N?s/m,which validates the proposed method of widening the damping adjustment range through adjusting the dislocation rate between the permanent magnet arrays.This article is supported by State Key Laboratory of Mechanics and Control of Mechanical Structures.