回转直动式电液伺服阀关键技术研究

【作者】 崔剑；

【导师】 丁凡；

【作者基本信息】 浙江大学 ， 机械电子工程， 2008， 博士

【摘要】 电液伺服控制系统以其功率—重量比大,系统响应快,负载刚性大,控制精度高的特点,广泛应用于冶金,矿山,船舶,工程机械,航空航天等工业控制领域。电液伺服阀作为电液伺服控制系统的核心元件,可将小功率的电信号输入精确快速的转换为大功率的液压能输出,其性能好坏直接影响伺服系统的特性及功能实现。回转直动式电液伺服阀因其具有结构简单紧凑、响应快、流量分辨率高、无加速度零飘、抗污染能力强及维护方便的性能特点,已成为流体传动及控制领域的一个重要发展方向和研究热点。提高电液伺服转阀的工作性能,能够提升电液伺服控制系统的控制特性,有助于满足日益增加的市场需求,进而推动流体传动及控制技术的进步。论文以回转直动式电液伺服阀的关键技术为研究对象,采用理论分析、解析计算、数值仿真和实验研究相结合的方法,对电液伺服转阀关键技术进行了系统、深入的分析和研究。提出了耐高压双向旋转比例电磁铁的新结构,电磁铁采用永磁励磁方式,具有环形工作气隙以及动磁式转子,偏置磁通与控制磁通相互作用,以差动方式工作;通过磁路分析和有限元仿真,阐述了电磁铁结构参数的作用机理及具体匹配关系,实验结果表明该电磁铁具有正磁弹簧刚度,最大输出转矩为±0.65 Nm,±5°时的转矩非线性和转角非线性分别小于1%和0.5%,转矩滞环和转角滞环分别小于4.5%和4%,工作带宽约为190 Hz。为提高电液伺服转阀的控制精度,论文提出了耐高压电涡流角度传感器的新结构和具体实现方案,传感器具有整体设计的导套和环形工作气隙,通过斜环状感应线圈配合半圆柱转子工作,使感应线圈阻抗和输出电压与转子角位移成比例;分析了传感器温漂的成因,提出了电涡流角度传感器无感线圈全桥回路温度补偿方法和新型差动电涡流式角度传感器结构,实现了传感器温漂的有效抑制;仿真和实验结果表明该传感器工作行程约为50°,线性段电感灵敏度为7.7×10^-4 mH/degree,电压灵敏度为9.8mV/°,40°-70°时的非线性误差小于0.8%,30℃-90℃温度范围内的传感器输出温漂由20%降至1%。结合耐高压双向旋转比例电磁铁和耐高压电涡流角度传感器,提出了不带角度反馈和带角度反馈两种形式的回转直动式电液伺服阀的结构方案,对其静、动态特性进行了仿真研究,阐述了结构参数和角度反馈对转阀工作特性的影响。有关各章内容分述如下:第一章从电—机械转换器,角度传感器和功率级液压组件的角度出发,探讨了回转直动式电液伺服阀关键技术的研究进展,分析总结了回转式电液伺服阀关键元件及转阀整体的结构特点和发展趋势。第二章对双向回转式电—机械转换器进行了结构分类,基于磁路原理建立了不同种类力矩马达的磁路模型,得出了电磁铁静态特性的解析方程式,对比分析了力矩马达的工作特点,归纳总结了励磁类型,气隙形状,转子种类和极面类型等结构要素对马达工作特性的影响;在此基础上提出了新型耐高压双向旋转比例电磁铁的结构,分析了其工作原理;并就其关键技术如耐高压结构设计,永磁材料分析和选型,软磁材料的对比选择,以及励磁线圈设计和负载弹簧选择进行了详细探讨。第三章建立了耐高压双向旋转比例电磁铁的磁路分析模型,得出了电磁铁的静、动态解析方程,分析了结构参数对电磁铁静、动态特性的影响;建立了电磁铁的有限元数值分析模型,通过仿真详细阐述了电磁铁结构参数的作用机理,结合磁路分析结果明确了电磁铁的具体结构参数,指出了电磁铁的工作特点;搭建了测试平台,实测了电磁铁的静、动态工作特性,并与仿真结果作了对比;介绍了电磁铁的功率驱动电路,对设计的PWM式双路反接卸荷式功率放大器的工作原理和特点进行了重点阐述。第四章对不同种类耐高压角度传感器的结构及性能特点进行了比较分析,归纳了感应线圈励磁方式,耐压导套结构,工作气隙类型,转子形状等结构要素对传感器工作特性的影响;在此基础上提出了新型耐高压电涡流角度传感器的结构,分析了其结构特点和工作原理;并就其关键技术如耐压导套材料选择以及驱动电路设计进行了详细论述。第五章建立了耐高压电涡流角度传感器的等效电路模型和有限元分析模型,通过仿真详细阐述了传感器结构参数的作用机理,分析了参数变化对传感器工作特性的影响,在此基础上确定了电涡流角度传感器的具体结构参数;讨论了传感器产生温漂的原因,介绍了无感线圈全桥回路温度补偿方法和新型差动电涡流式角度传感器结构:搭建了测试平台,实测了传感器的电感特性,全桥输出特性和温漂。第六章结合耐高压双向旋转比例电磁铁和耐高压电涡流角度传感器,提出了不带角度反馈和带角度反馈两种结构形式的回转直动式电液伺服阀,对其工作原理和性能特点进行了分析;建立了转阀的传递函数式,采用MATLAB构建了数值仿真模型,对转阀的静、动态特性进行了仿真研究,阐述了结构参数和角度反馈对转阀工作特性的影响。第七章概括了全文的主要研究工作和成果,并展望了今后需进一步研究的工作和方向。更多还原

【Abstract】 With large power/weigh ratio, fast response, high immunity to load variations and high level of control precision, the electrohydraulic servo control system has been widely used in many industrial applications such as metallurgy, mining, marine, construction machinery and aerospace. As key components of an electrohydraulic servo control system, the electrohydraulic servo valves can transfer low-power electrical signal to large-power hydraulic output quickly and precisely, and have a direct influence on performance and characteristics of the whole servo system. Rotary direct-drive servo valve, due to its compact structure, fast response, high flow resolution, zero acceleration drift and easy maintenance, has come to be an important trend in fluid power transmission and control. Improving the working performance of the rotary servo valve, will enhance the control performance of the electrohydraulic servo system, satisfying the market requirements and pushing advancement in techniques of fluid power transmission and control.Based on theory analysis, analytical computation, numerical simulation and experimental study, the rotary direct-drive servo valve is systematically, deep analyzed and researched in the thesis. A high-pressure bi-directional rotary proportional solenoid with permanent-magnet polarizing, ring type working air-gap and moving-magnet rotor, is put forward. It works in differential mode with the polarizing and control flux interactions. With magnetic circuit analysis and finite element simulation, the action mechanism and matching relations of the solenoid structural parameters are analyzed in detail. The experimental results indicate the solenoid has positive magnetic stiffness and output torques of±0.65 Nm with the torque non-linearity and angle non-linearity less than 1% and 0.5% respectively at±5°working range. Its torque hysteresis and angle hysteresis is less than 4.5% and 4% respectively and the frequency bandwidth is 190 Hz. For improving the control precision of the rotary servo valve, a high-pressure eddy current angle sensor is also presented. An oblique ring-shaped sensing coil and a symmetric semi-cylindrical rotor are utilized, making the coil impedance and the output voltage proportional to the angular displacements. Based on theoretical analyses of the sensor temperature drift, the differential eddy current angle sensor structure and temperature compensation method employing non-inductive coil and bridge circuit are also presented, achieving better temperature stability. The measured and simulation results show that the sensor has a linear working range of 50°with inductance sensitivity 7.7×10^-4 mH/degree and voltage sensitivity 9.8 mV/°. Its non-linearity is less than 0.8% at working range 40°-70°, and the temperature less than 1% over 30℃-90℃. Together with the high-pressure bi-directional rotary proportional solenoid and the high-pressure eddy current angle sensor, two types of rotary direct-drive servo valve, one with and one without angular displacement feedback, are raised. Based on simulation, the static and dynamic characteristics of the rotary valve are analyzed, and the influence of the structural parameters and angle feedback is also presented.The main content of each chapter is summarized as following:In chapter 1, the research progress of electrical-mechanical converter, angle sensor and rotary valve, which constituting the whole rotary direct-drive valve, is introduced. The design feature and development trend of the whole rotary direct-drive valve and its key components are summarized.In chapter 2, the bi-directional rotary electrical-mechanical converters are classified by different structures. Based on magnetic circuit principal, the magnetic circuit models of different kinds of torque motors are established, and the analytical functions describing the static characteristics of the solenoid are also deduced. The working characteristics of torque motors are compared and the effects of magnetization type, air-gap shape, rotor style and polar-face form are summarized. Then a novel high-pressure bi-directional proportional solenoid is presented, and its working principals are analyzed. The key technologies of the solenoid, including high-pressure structure design, permanent magnet material, soft magnet material, excitation coil and loading spring, are also discussed.In chapter 3, the magnetic circuit model of the high-pressure bi-directional proportional solenoid is established, and the influences of structural parameters are analyzed based on the deduced static and dynamic analytical functions. The finite element model of the solenoid is also established and the action mechanism of the solenoid structural parameters is analyzed in detail. Together with the magnetic circuit analysis results, the specific structural parameters are determined. Then the static and dynamic characteristics of the solenoid are measured and compared with the simulation results. Furthermore the power amplifiers for solenoids are introduced, and the working principals of the PWM double-way inverse-relief power amplify are analyzed.In chapter 4, the structural features and working characteristics of different kinds of high-pressure angle sensor are compared, and the effects of coil magnetization type, sleeve structure, air-gap type and rotor style on sensor characteristics are summarized. Then a novel high-pressure eddy current angle sensor is presented, and its operation principals and structural features are analyzed. The key technologies of the sensor, including the sleeve material and sensor driving circuit, are also discussed.In chapter 5, the equivalent circuit model and finite element model of the high-pressure eddy current angle sensor are established, and the action mechanism of the sensor structural parameters is analyzed in detail based on simulation. The specific structural parameters of the sensor are determined according to the FEM simulation results. Based on theoretical analyses of the sensor temperature drift, the differential eddy current angle sensor structure and temperature compensation method employing non-inductive coil and bridge circuit are also presented. The inductance, bridge circuit output and temperature drift characteristics of the sensor are measured with an experiment platform.In chapter 6, based on the high-pressure bi-directional proportional solenoid and the high-pressure eddy current angle sensor, two types of rotary direct-drive servo valve, one with and one without angular displacement feedback, are put forward. Its working principals and performance features are discussed, and the transfer functions are also given. The static and dynamic characteristics of the rotary valve are analyzed based on MATLAB numerical simulation model, then the effects of the structural parameters and angle feedback on valve performance features are discussed in detail.In chapter 7, all achievements of the dissertation are summarized and the further research work is put forward.更多还原