Impedance Matching Of Giant Magnetostrictive Transducer And Its Experimental Study

In recent years,with the advent and developme nt of rare-earth giant magnetostrictive materials,many properties of transducers,such as the output power,controllability and frequency response,have been significantly improved,which has attracted the attention and research of scholars at home and ab road.However,the impedance characteristics of giant magnetostrictive transducer are very complex,and there are great differences between the impedance parameter s of large signal and small signal.In this paper,a low-frequency high-power rare-earth giant magnetostrictive transducer and its impedance characteristics and impedance matching theory and method under the condition of large signal are studied,which provides important theoretical and practical guidance for the efficient energy transfer between the transducer and the power supply.The main work and innovation of this paper are as follows:(1)According to the impedance characteristics of the rare-earth giant magnetostrictive transducer studied in this paper,the impedance matching theory and design method are described in detail.The static i mpedance matching principle of single-tuning and double-tuning impedance matching method is simple and easy to realize.The dynamic impedance matching method based on switching capacitor can follow the change of transducer impedance.The continuous active impedance matching method can achieve dynamic,fast,continuous and accurate impedance matching,and the simulation results verify the accuracy and effectiveness of its theoretical analysis.(2)The experiment platform of longitudinal mode giant magnetostrictive transducer is designed and manufactured to simulate the impedance cha racteristics of giant magnetostrictive transducer.This paper introduces the design theory and method of each part of giant magnetostrictive transducer in detail,including the coil and magnetic circuit design,prestress mechanism design,etc.Then,the finite element magnetic field simulation analysis and modal simulation analysis by COMSOL are carried out for the giant magnetostrictive transducer designed in this paper,which verifies the rationality of the magnetic field design and mech anical structure design.(3)The principle of phase difference detection and impedance measurement method based on FFT analysis is described in detail.Compared with the classical impedance measurement method,it can realize fast sweep frequency measurement of impedance parameters of transducer under large signal,and significantly improves the anti-interference ability of harmonic and noise,and improves the measurement accuracy.According to this method,a large signal im pedance scanning experiment platform based on Lab VIEW and data acquisition card NI6361 is designed,and the impedance characteristics of the giant magnetostrictive transducer designed in this paper under the large signal are measured and compared with the small signal impedance parameters obtained by the impedance analyzer.(4)A dynamic impedance matching experiment platform based on Lab VIEW and data acquisition card NI6361 is built.It can dynamically adjust the parameters of the matching network to keep the high power factor output of the power amplifier.And the experiment results prove the effectiveness of this scheme.