Study On Load Modeling And Driving Application For Magneto-rheological Fluid Damper

The Magneto-rheological fluid (MRF) damper has broad prospects in intelligentvehicle suspension system. Based on Magneto-rheological effect, the MRF dampergenerates controlled magnetic field under exciting current and which makes the flowcharacteristics of MRF changed. Then it get the purpose of vibration attenuation inreal-time by varying the magnitude of damping force. As the driving circuit load, themagnetic circuit is consisted of damper piston, cylinder block and the dampingclearance, and which has the essential influence on the dynamic response characteristicsof MRF damper. In actual load, the eddy current led by iron core and multilayerstructure of damper coils has a significant impact on the frequency responsecharacteristics. Modeling analysis on the load characteristics, as the guidance for currentsource design, has important academic value and practice significance. In this paper, theload characteristic of MRF damper is analyzed and a new load model is proposed.Furthermore, a controlled current source is designed which is adapted to the loadcharacteristic of MRF damper. Lastly, the idea and principle for current sourceimplementation are described in detail. The main content of the study is as follows:①The MRF and MRF effect are introduced and the different applications inengineering practice of MRF damper are described. Then this paper lists the loadcharacteristics of MRF damper and introduces the state-of-art at home and abroad ofcontrolled current source. The existing problems are summarized, and the main work inthis paper is introduced.②According to the particular structure of MRF damper and considering thecomplex nonlinear magnetic field, this paper adopt experimental modeling techniques.A new theoretical model is put forward and analyzed by experiment. And thus itresearches the effect generated by different inductive components of models. Theseresearches can provide some references on the effective connection between loadcharacteristic and drive development technique of MRF damper.③In order to design a controlled current source with fast dynamic response andgood linearity for MRF damper, two different kinds of voltage control of switchingpower supply are compared. Moreover, the advantages and disadvantages betweenvoltage control and current control are discussed comprehensively. At last, the designproposal of voltage-type PWM DC/DC Buck circuit is determined and the theoretical support for the overall design of the current source by inferring the principle of Buckcircuit is supplied.④According to the provided structural design, a detailed design and analysis ofthe various modules with modular principle is carried out. Moreover, the detailschematics and parameters of different modules are determined such as main circuitmodule, PWM control module and single-chip control system and so on. Finally, thesimulation of each module circuit based on the Saber software to simulate verifies thecircuit design is feasible and correct.⑤At last, the software program of different modules such as data acquisition, PIDcontrol module and DA conversion on the basis of hardware design of this controlledcurrent source are completed. Then the relation of control voltage and duty ratio intheory is calculated and the parameters of digital PID controller by modeling andsimulation with Simulink are determined. Finally, the controlled current source systemis overall tested, and the linearity and the response time of output current.