Control Design Of Semi-active Suspension Reclaiming Energy With Linear Motor Based On Variable Battery Charging Voltage

With the global non-renewable energy decreasing and environment protection awareness increasing,energy saving technology has become an important technology in the automotive design process.The electromagnetic semi-active suspension reclaiming energy(ESASRE)can not only increase vehicle riding comfort but also recover suspension vibration energy.Therefore,it has certain research value.This paper presents variable battery charging voltage control method with linear motor and studies two charging voltage calculation methods in order to improve work effect of ESASRE.The main research work of this paper is as follows:The mathematical model of half-car ESASRE and the semi-active actuator with linear motor based on variable battery charging voltage are established.Mechanical properties of the semi-active actuator are studied under different charging voltage and speed.The evaluation indexes of the suspension using and reclaim energy performance are established.The controller for ideal semi-active control forces is designed based on LQG strategy.The charging voltage calculation method based on numerical fitting is designed.Mechanical properties of the semi-active actuator are obtained by numerical simulation.The quasi linear relation functions of charge voltage about suspension relative speed and damping force are obtained based on least square method.Relevant functions are united and the charging voltage can be obtained according to suspension relative speed and ideal semi-active control force needed correspondingly.The charging voltage calculation method based on motor equivalent model is designed.This method equivalent the three-phase linear motor with bridge rectifier to a single-phase motor model.Back EMF coefficient,electromagnetic thrust coefficient,resistance and inductance of the single-phase motor equivalent model are obtained through numerical fitting.The calculation formula of charging voltage can be obtained correspondingly.The simulation models of the passive suspension,the ESASRE based on numerical fitting,the ESASRE based on motor equivalent and the ideal semi-active one areestablished by Matlab/simulink software.Performance comparisons and analyses among the suspensions are conducted,verifying the advanced nature of variable voltage charging control method.Results show that suspension quadratic performance indexes of the ESASRE based on numerical fitting reduce by 28.4% compared with the passive suspension.The correlation coefficients of the ESASRE based on numerical fitting between the front and rear suspensions and real control forces are 0.9692 and 0.9746.55.6% and 61.5% of vibration energy of the front and rear suspensions of the ESASRE based on numerical fitting are reclaimed to flow to batteries.Suspension quadratic performance indexes of the ESASRE based on motor equivalent model reduce by 30.0% compared with the passive suspension.The correlation coefficients of the ESASRE based on motor equivalent model between the front and rear suspensions and real control forces are0.9788 and 0.9836.57.8% and 56.7% of vibration energy of the front and rear suspensions of the ESASRE based on motor equivalent model are reclaimed to flow to batteries.So,the newly two developed methods can not only achieve better suspension comprehensive performance,but also reclaim most of suspension vibration energy.