Research On The Key Technologies Of Low-Power Proportional Electro-Mechanical Converter

As key components of electrohydraulic servo/proportional valves,the proportional electromechanical converters have played an important role in the electrohydraulic control systems of many national defense and civil industries such as aerospace,military,machine tool, mining,metallurgy and construction machinery.With the ever-increasing demands of industry sustainable development,requests for higher and broader performance of the proportional electromechanical converters have been put forward.Reducing power consumption of the proportional electromechanical converters could reduce cost and coil temperature rise to improve working stability,especially used in many industries which are short of power supply such as aerospace,deep sea,field operation,and has come to a hot topic of research on the electromechanical converters.Research on the low-power proportional electromechanical converters would help to better meet the ever-increasing needs of market and sustainable development for energy conservation.Based on theory analysis,analytical computation,numerical simulation and experimental study,the low-power proportional electromechanical converters are systematically,deep researched in the thesis.Adopting a low-power strategy by introducing double radial operating airgaps and reducing axial non-operating airgaps,a low-power uni-directional proportional solenoid for high pressure is presented.Besides,working in differential mode with the permanent polarizing and control flux interactions,a low-power bi-directional linear force motor for high pressure is presented.With magnetic circuit analysis and finite element simulation,the action mechanism and matching relations of the structural parameters are analyzed in detail.The test results indicate the solenoid has rated working range of 1.4 mm,rated output force of 96 N, high linearity,low hysteresis,good dynamic characteristics,rated stable power consumption of merely 9.5 W,and low coil temperature rise.The test results indicate the force motor has rated working range of±1 mm,rated output force of±100 N,positive magnetic spring stiffness of 10 N/mm,high linearity,low hysteresis,good dynamic characteristics,rated stable power consumption of merely 8.3 W,and low coil temperature rise.As an application example of the low-power uni-directional proportional solenoid,a low-power pilot relief valve is successfully developed,and the stable and transient characteristics of the valve are obtained by simulation and test.The main content of each chapter is summarized as following:In chapter 1,from standpoints of the electromechanical converters for the electrohydraulic servo/proportional valves and application of low-power technique in the electromagnetic valves, the research progress of the low-power proportional electromechanical converters is introduced. The structural and low-power feature,development trend of the electromechanical converters for valves are summarized.In chapter 2,based on analysis of energy conversion relation and efficiency of moving-iron type electromechanical converters,several methods for reducing power consumption are summarized.Due to the structural feature of classic moving-iron type proportional electromechanical converters,a low-power strategy is presented and applied in the specific high-pressure structure of both uni-directional proportional solenoid and bi-directional linear force motor.In chapter 3,the magnetic circuit models of two low-power proportional electromechanical converters for high pressure are established,and influences of the structural parameters or magnetic circuit parameters on static force characteristics are analyzed as the design basis.The finite element models of the converters are also established,and the action mechanism of the structural parameters are analyzed in detail.Together with the magnetic circuit analysis results, the specific structural parameters are determined,and the working features of two type converters are analyzed.Then the constitution,cause,theoretical calculation method of power loss and the coil temperature rise characteristic are analyzed.In chapter 4,the constitution,principal,error analysis and test methods of a test system for force characteristics are introduced.Influences of the amplifier performance and test methods on test results are analyzed.Based on the force and displacement characteristics test systems,the static and dynamic characteristics of two low-power proportional electromechanical converters for high pressure are measured,and compared with the simulation results.Furthermore,the power consumption and coil temperature rise characteristics of the converters are measured.In chapter 5,as an application example of low-power uni-directional proportional solenoid, a low-power pilot relief valve is developed.Based on the established simulation model,the stable and transient characteristics of the valve are obtained,and influences of the structural and performance parameters of the low-power uni-directional proportional solenoid on stable characteristics of the valve are discussed.Trough the test system for pressure control valves,the stable and transient characteristics of the low-power pilot relief valve are measured,and compared with the simulation results.In chapter 6,all achievements of the dissertation are summarized and the further research work is put forward.