Nonlinear Modeland Experiment Research Of Magnetostrictive Vibration Generator

The vibration generator based on magnetostrictive materials can be used in the wireless sensors and other embedded,portable electronic devices,where the traditional power supply can’t directly provide electric energy.However,magnetostrictive materials have significant nonlinear characteristics and eddy current effect,so the study of the vibration generator’s nonlinear model has important theoretical and realistic significance.In this paper,first,the research situation of the vibration generator is reviewed and the development situation of magnetostrictive vibration generator is introduced emphatically.Second,aiming at the nonlinear characteristics of the Galfenol,which is a new kind of magnetostrictive material,the gibbs free energy model is used to study the nonlinear coupling relations between the magnetic induction,magnetostriction,magnetic field and stress,and a three-dimensional nonlinear model of Galfenol alloy considering the anisotropy of material is set up.Thirdly,comparisons between the calculated and experimental results verify the exactness of the proposed model of Galfenol.The constitutive equation with eddy current effect and mechanical-electro equations of the Galfenol vibration generator are combined to establish a nonlinear mechanical-magnetoelectro coupled dynamic nonlinear model with eddy current effect for the stress-driven Galfenol vibration generator.The established model of the generator is used to calculate the performances of the generator under different operating conditions(such as bias magnetic field,stress amplitude,frequency,resistance and the number of slices,etc.).Simulated results show that the model can determine the optimal bias magnetic field,the optimal load resistance and the suitable filaments for the maximum energy extraction of the generator.Fourthly,the material’s constitutive equation,the maxwell’s equations and circuit-to-field coupling are adopted to derive the expressions of the internal magnetic induction and the internal magnetic field of the generator.The finite element method is used to solve these expressions,the distribution of the internal magnetic field,the magnetic induction and the current density for the generator with eddy current effects are obtained and analyzed.Finally,the characteristic curves of a Galfenol transducer are measured,and the output electrical performances of the transducer are forecasted.These studies play an important role in the design,performance forecast and use of magnetostrictive vibration generator.