Research On The Intelligent Technology Of Closing Course In AC Contactor With Feedback Control

With the rapid growth of China's industrial scale,the performance requirements of AC contactors are getting higher and higher,the application of intelligent control technology to improve the performance of AC contactor is of great significance.In this paper,the key technology of intelligently controlling closing course in AC contactor is studied deeply,which mainly focuses on software simulation,hardware control and so on.Firstly,the simulation model of the electromagnetic mechanism is established by the finite element simulation software,the transient magnetic field simulation function module of the simulation software is used to simulate and analyze the operation characteristics of the electromagnetic mechanism under AC voltage excitation and DC voltage excitation respectively.The results show that taking DC voltage as the coil excitation in AC contactor has obvious advantages than the AC voltage in the intelligent control.Secondly,in this paper,the planning current curve is designed and the coil current control module is designed to make the actual coil current track the planning current,so as to improve the performance of AC contactor and reduce the contact bounce.By using AC contactor,the DC excitation simulation and test of the electromagnetic mechanism are carried out.Through the analysis of the contact force of the contactor in each stage of the suction process,the suction margin of the electromagnetic mechanism in different stages is adjusted,to reduce or even eliminate the contact bounce on the premise of meeting the requirements of total closing time,and constructs a reasonable plan suction curve.In order to make the contactor operate according to the plan suction curve and realize the control easily,the dynamic equation of the electromagnetic mechanism is used to transform the planned suction curve into the planned current curve which can be used as the direct control quantity.Then,According to the characteristics of the current curve obtained by the planning,this paper completes the design of the control system through the hardware software design.The purpose of this control system is to makes coil current to track the change of current curve by closed-loop feedback control,so as to improve dynamic characteristics of the closing process in AC contactor.In the hardware design,the control system draws on the high-frequency switching power supply technology,introducing the digital-analog mixed current closed-loop control system.Experiments show that the control system not only solves the contact bounce problem of the AC contactor during the pull-in process,greatly reduces the number of contact bounce and bounce duration,and also has the functions of resisting voltage short-time drop,protection of voltage loss,which contributes to improving the reliability of the contactor.Besides,under the control of the control system,the total pull-in time compared with the original electromagnetic system has been shortened.Finally,taking into account that the long time use and frequent action will cause some problems in AC contactor,such as aging of reactive spring and movable part wear,which makes the operation characteristic change.In view of this problem,the self-tuning control system is designed.In this system,real-time correction of the planning current curve,which makes the dynamic characteristics of AC contactor always maintained in a more ideal state.The research results in this paper can provide an effective reference for the improvement and optimization of the electrical equipment with electromagnetic structure in the control technology and related theoretical research.