Research On Multifunction Energy Regenerative Suspension Control System Using Linear Electromagnetic Actuator

Suspension system is an important part of the automobile,which can directly affect the ride comfort,operation stability and driving safety of the automobile.However,the performance of traditional hydraulic suspension cannot be automatically adjusted according to the driving conditions of the automobile,which cannot meet the needs of people for ride comfort and safety.Active suspension is the ideal shock absorber in theory and practical application,which can greatly improve the dynamic performance of suspension,but it has the problem of energy consumption.In view of the above problems,the comprehensive suspension which can realize energy recovery and adjustable control performance has become a hot spot in the current suspension controller research.In this paper,a multifunctional energy-fed shock absorber is designed based on linear motor and bidirectional DC/DC power converter,and its control performance and energy recovery effect are studied.On the basis of analyzing the working principle and structure of multifunctional energy-fed suspension,the equivalent mathematical model of linear motor,two-degree-of-freedom suspension model of automobile and road input model are established.The recovery potential and existing problems of linear motor as energy-fed shock absorber are studied.And the performance evaluation index of energy-fed suspension is proposed to provide theoretical basis for the design of motor drive system.By analyzing the magnitude range of induced electromotive force and control current at both ends of linear motor in active mode and energy feeding mode of suspension,the overall design scheme of motor driver is determined.It includes H-bridge system with rectifier and inverter functions,bidirectional DC/DC power converter and energy storage components.By studying the operation state of the control circuit in different modes,the influence of circuit components on the performance of the controller is analyzed.The research shows that the controller system can realize the energy flow among the motor,the storage battery and the super capacitor,and provide physical conditions for the corresponding control strategy design.Internal resistance and control circuit resistance of linear motor have great influence on equivalent damping coefficient and energy utilization rate,while other parameters only affect the quality of control current.Based on the working characteristics of motor,the current control strategy and suspension control strategy are designed.And the simulation model of linear multifunctional energy-fed suspension is built with the drive circuit system.The dynamic performance and energy efficiency of suspension are comprehensively analyzed by using relevant evaluation indexes.The results show that the linear motor drive system can achieve the control effect under the fuzzy PID current control strategy.The ride comfort of energy consumption full active control is improved by about 26% compared with passive suspension;Under the semi-active control of energy feeding,the energy recovery efficiency can reach about 20%;The hybrid control strategy adjusts the running state of the motor through the mode switching criterion,and can adjust between the damping performance and energy consumption according to the driving demand.The hybrid control strategy not only improves the comprehensive performance of the suspension,but also makes up for the shortcomings of the traditional single performance optimization strategy,and increases the endurance of the electric vehicle.At the end of this paper,the physical prototype of DC/DC power converter,PWM control verification test system and hardware-in-the-loop test are built to verify the proposed controller and control strategy in part.The results show that the multifunctional energy-fed shock absorber based on linear motor and bidirectional DC/DC power converter is feasible and practical.The new structure and control method proposed in this paper can provide a new way for active control and energy recovery of vehicle vibration,and also provide necessary design basis for electrification of suspension system of electric vehicles in the future.