Research On Key Technologies Of Moving-coil Proportional Electromagnet

As key components of electrohydraulic servo valves, the moving coil proportional electromagnet plays an important role in the electro-hydraulic control system of areas such as national defense and civil industries. Its performance directly affects the quality of the control system. Existing research on moving-coil proportional electromagnet is discrete and lack of systematic, which make it difficult to show its overall structural characteristics systematically. Then the structure cannot be used efficiently, which would affect the design of the solenoid. It is beneficial to improve the performance, by systematic and scientific research on the moving-coil electromagnet, better satisfy the booming market demand, and promote the development of related technology while application area expanded.The key technologies of moving-coil proportional electromagnet are deeply researched in the thesis, for the target of improving the static and dynamic performance, based on theory analysis, numerical simulation and experimental study. The thesis first delves into the structural characteristics of moving-coil proportional electromagnet, and then establishes the magnetic circuit model and numerical model based on magnetic circuit analysis method. On this basis, combined with finite element analysis method, the finite element simulation model is established. Then based on the magnetic circuit analysis and finite element simulation method, the effect of various structural parameters is presented in detail, with which the theoretical model is optimized. The prototype of optimal structure is manufactured and the test system is established. Then the coil temperature rise characteristic, force-stroke characteristic and current-force characteristic are obtained by test research. The results of the test show that the solenoid has rated working range of 4mm, rated output force of 4.3N, and a step-response time of less than 5ms, which proved to be a good dynamic characteristic. The results of experiment are accordant with that of simulation, with which the theoretical model is verified. Subsequently, based on the verified theoretical model, further explore on moving-coil electromagnet is made, mainly include the effect of shaped structure to the solenoid. Asymmetric pole shoe and shaped magnet are designed, and analyzed by modeling. The results show better characteristics that traditional with an increase of 9.98% in the output force.The main content of each chapter is as following:In chapter 1, from standpoints of the electrical-mechanical converters for the electro-hydraulic servo/proportional valves, the research progress on the key technologies of moving-coil proportional electromagnet is introduced. The classification, structural and development trend of the electrical-mechanical for valves are summarized.In chapter 2, structural of moving-coil proportional electromagnet is proposed, and its work principle is analyzed. Based on the magnetic circuit and finite element method, which respectively based on the laws of magnetic circuit and magnetic field theory, the moving-coil proportional electromagnet is analyzed. The magnetic circuit model which based on magnet excitation, the dynamic model and the finite element model of the moving-coil proportional electromagnet are established. And then the expression of output force of the moving-coil proportional electromagnet is obtained. Based on the magnetic circuit analysis method, the action mechanism and ways of influence of the structural parameters to the characteristics of the electromagnet is deeply researched, by the use of finite element analysis software. Optimum direction of the structure is analyzed. Then the structural parameters of the moving-coil proportional electromagnet, which are optimized, are determined. The static characteristics simulation curves of the moving-coil proportional electromagnet are obtained.In chapter 3, the prototype of the moving-coil proportional electromagnet is developed. In order to obtain its characteristics, the test system of the electromagnet is established, of which the principal and constitution, the performances and test methods of the electromagnet, are introduced. Based on the test system, experimental study of the prototype is made. The static and dynamic characteristics of the electromagnet are obtained, while the coil temperature rise is verified. The test results of the prototype are compared with the simulation results, with which the finite element model is verified.In chapter 4, the way to improve output force characteristics of moving-coil proportional electromagnet is summarized. The effect to the characteristics of electromagnet of shaped structural parameters has been further explored. The structure of moving-coil proportional electromagnet, which is further optimized with shaped structural parameters, is determined. And the simulation results are compared with before, with which the effect of shaped structure to the characteristics of electromagnet is proved to be good.In chapter 5, all achievements of the dissertation are summarized and the further research work is put forward.