Research On Fast Actuation Technology Of Magnetostrictive Actuator

Electromagnetic actuators are an indispensable type of driving device in industrial production,and magnetostrictive actuators have received widespread attention.The core moving part of this actuator is a magnetostrictive rod,and its maximum magnetostrictive strain can reach more than 1000ppm.Magnetostrictive actuators have the characteristics of high precision and fast response.High-speed valves,precision displacement stages,and other fields have put forward higher requirements on the output speed of magnetostrictive actuators.Magnetic circuit components in electromagnetic actuators are often good conductors of electricity,and eddy currents are generated inside them under the action of high-frequency excitation magnetic fields.Eddy current loss is an important factor that limits the high-speed action of the actuator.A common way to reduce eddy current loss is to make the entire conductor in the magnetic circuit into a partitioned insulated structure.This structure is widely used in the magnetic cores of electromagnetic motors,transformers,and other equipment.In this study,the magnetic circuit equation and the magneto-mechanical coupling transfer function of the magnetostrictive actuator are established,and theoretical analysis and simulation have verified that the equivalent conductivity of the laminated silicon steel core is lower than that of the monolithic silicon steel core,which is beneficial Reduce the eddy current loss,and then increase the effective magnetic flux in the magnetic circuit.Fifty insulating silicon steel sheets with a thickness of 0.2mm are stacked and bonded to form a laminated structure magnetic core of a magnetostrictive actuator.The structure of the coil is optimized,and an excitation coil with 8 turns and an inductance value of 1.2μH is wound with a multi-strand insulated stranded enameled wire so that under the condition of a certain driving voltage amplitude,the current rise rate is increased.The output speed of the actuator.Two magnetostrictive actuator prototypes with laminated silicon steel magnetic core and monolithic silicon steel magnetic core were produced,and the load mass of the two prototypes was 1.5g.Under the excitation of a sine wave current with an effective value of 35A(rms)and a frequency of 2kHz,the laminated silicon steel core actuator can output vibration with an amplitude of 11.1μm and a frequency of 4kHz,which is higher than the output of a monolithic silicon steel core actuator.The speed is 44.2%higher,which shows that partitioning and insulating the magnetic circuit components can effectively increase the output speed of the actuator.In addition,the relationship between the effective value of the excitation current and the amplitude of the actuator is studied.The mechanical resonance frequency of the laminated silicon steel magnetic coreactuator is simulated,and the LC series resonance circuit is used to expand the frequency band of the excitation current and improve the high-frequency performance of the actuator.Under the current excitation with the effective value of 35A(rms)and the frequency of 1kHz-4kHz,the amplitude-frequency characteristic curves of the two actuator prototypes at the vibration frequency of 2kHz-8kHz have been experimentally measured.When the vibration frequency is 4kHz,the two prototypes both output the maximum amplitude.When the vibration frequency is less than 5kHz,the amplitude of the laminated silicon steel core actuator is greater than that of the monolithic core actuator;when the vibration frequency is greater than 5kHz,the amplitude of both is smaller.The mechanical structure of the laminated silicon steel magnetic core magnetostrictive actuator proposed in this paper is simple and compact.The laminated structure reduces the high-frequency eddy current loss of the magnetic circuit components,and the resonance structure improves the high-frequency performance of the actuator.In the future,structures or materials with lower equivalent conductivity can be used to further reduce the eddy current loss of magnetic circuit elements,which provides a feasible design idea for the design of other magnetostrictive actuators used in fast actuation applications.