Research On Design Methodology And Experiment Of Electromagnetic Active Dynamic Vibration Absorber

With the increasing requirement of consumers on automobile riding comfort,vibration and noise problem has become one of the major concerns.The resersches on suppressing vibration are of great practical significance.At present,the dynamic vibration absorbers(DVAs)have been widely used for controlling the automotive engine and drive-train vibration in order to enhance the noise,vibration and harshness(NVH)performance of vehicles.However,the passive DVAs are most effective within a narrow frequency band in the vicinity of the tuned absorber frequency.In order to improve the NVH performance of vehicles,electromagnetic dynamic vibration absorber(EDVA)consisting of an electromagnetic actuator and an elastic element is proposed for control of engine vibration,and the aspects including the design of the electromagnetic actuator,active vibration control method and the bench test are studied in this research.The main works in the dissertation are summaried as follows:(1)A new E-type EDVA is proposed for structural vibration control,based on an E-type electromagnet as the actuator.The mathematical model for electromagnetic force is deduced,which show that the electromagnetic force has complex nonlinear relationship with current and air gap.Finite element method for numerical analysis of electromagnetic field is stated to verify the correctness of mathematical model.The kinematics equation of E-type EDVA is established using the mathematical model of electromagnetic force,which is used to analyze the force characteristics.The numerical simulation results show that the electromagnetic force consists of static force and harmonic force,and the frequency of harmonic force is double the frequency of sinusoidal current.The reaction mass of E-type EDVA exerts a driving force upon primary system by reciprocating movement under the harmonic electromagnetic force,and the results show asymmetric variations in the driving force.The effect of errors between the actual driving force and ideal driving force on vibration control is discussed.At last,experiment bench for a plate is set up,and the theoretical analysis were verified by experiments.(2)A hybrid proportional EDVA consisting of a proportional electromagnetic actuator and an elastic element is proposed for control of engine vibration during idling.The design of the proportional electromagnetic actuator is realized considering the geometric parameters of the core to achieve nearly constant magnetic force over a broad range of its dynamic displacement but proportional to square of the current.The dynamic characteristics of the EDVA are analyzed analytically and experimentally.The effects of various geometricparameters of the actuator such as the slopes and width/height,and the air gaps on the resulting magnetic force characteristics are evaluated using a finite element model,and verified experimentally.The passive elements supplement the driving force so as reduce the proportion of the active force and thus the energy demand,and these suggest minimal power demand of the EDVA,when it is operated around its resonant frequency.(3)A methodology is proposed to achieve magnetic force proportional to current and consistent with the disturbance frequency.The hybrid proportional EDVA is subsequently applied to a single-degree-of-freedom primary system with an acceleration feedback control algorithm for attenuation of primary system vibration in a frequency band around the typical idling vibration frequencies.The effectiveness of the hybrid proportional EDVA is evaluated through simulations and laboratory experiments under harmonic excitations in the 20-30 Hz frequency range.Both the simulation and measurements show that the hybrid proportional EDVA can yield effective attenuation of periodic idling vibration in the frequency range considered.(4)For the case that the driving force of hybrid proportional EDVA can not satisfy the required amplitude,a hybrid electromagnetic dynamic vibration absorber consisting of a permanent magnet actuator and a leaf spring is proposed.In order to improve the magnetic induction intensity of air gap,the sensitivity of structure parameters to evaluation index is analyzed by single factor test design and orthogonal test design.The optimum design method of actuator structure parameters is established.Aiming at optimization design,in conjunction with orthogonal test design method,response surface methodology(RSM)and genetic algorithm,the surrogate model of magnetic induction intensity of air gap is constructed.The prototype of EDVA is subsequently developed,and the driving force is tested.The simulation show that the EDVA can yield effective attenuation of vibration in a frequency wide band with Least Mean Square(LMS)adaptive control algorithm.For vibration suppression,this dissertation conducts a systematic research on the EDVA.In actual engineering,which a simple and reliable control strategy is adopted to realize active vibration control.The research ideas and proposed approaches of this dissertation have a good potential guidance and application in the engineering field of automotive engine vibration control.