Research Of2D Electro-Hydraulic Proportional Direction Valve And Its Digital Controller

The electro-hydraulic proportional valve not only can realize the complex control functions, but also has the advantages of strong anti pollution ability, low cost, quick response. As this reason, electro-hydraulic proportional valve is widely used in the electro-hydraulic control system which is always applied in the field of machinery, metallurgy, shipbuilding, textile and so on. Proportional control amplifier is the core of the electro-hydraulic proportional control system. Its performance and reliability have great effect on the performance and stability of the whole control system.In this paper, the structure of a new type of2D electro-hydraulic proportional direction valve-2D electro-hydraulic proportional direction valve with a simplified full-bridge pilot and a pretended spool-is proposed. Its working principle and the step response characteristic of the pilot stage of this valve are discussed. A simplified hydraulic bridge is utilised in this valve. As this line, the structure of the2D electro-hydraulic proportional direction valve can be greatly simplified. In addition, a digital proportional control amplifier based on STC12C5A60S2is proposed and developed. By using PWM anti-unloading power driver circuit and using software to achieve some functions previously realized by hardware, the flexibility of the system has been improved and the total performance in steady and dynamic states has also been greatly improved.This thesis is divided into six chapters, the specific contents arc as follows:The first chapter introduces the development and the research status of electro-hydraulic proportional direction valve and proportional control amplifier. Then the main research contents and the significance of the thesis arc expounded.The second chapter presents the structure of the2D electro-hydraulic proportional direction valve with a simplified full-bridge pilot and a pretended spool. Its working principle is described in detail. Then the structure of electric-mechanical converter which is always used in electro-hydraulic proportional valve-the ratio electromagnet-is clarified. In the end of this chapter, you will learn how the ratio electromagnet works.In the third chapter, a dynamic mathematical model of the pilot stage of the2D electro-hydraulic proportional direction valve with a simplified full-bridge pilot and a pretended spool is established. Then studying the step response characteristics of this valve by using simulation software-Matlab. In addition, a mathematical model of the ratio electromagnet is also established and its working principle is discussed further.The forth chapter the overall scheme of the system-the digital proportional control amplifier based on STC12C5A60S2-is briefly introduced. Then various hardware modules of the digital proportional amplifier, including the main control module, the input interface circuit, the power amplifier circuit, are described in detail. At last, the design of the program of the digital proportional amplifier, including flutter signal generation subroutine, current PID control subroutine, input and display subroutine are specifically described.In the fifth chapter, we built an experimental platform to study the input and output characteristics of the digital proportional control amplifier and the performance of the dither compensation for hysteresis. The experimental results show that:firstly, the digital proportional control amplifier has good Input and output characteristics and the performance of dither compensation for hysteresis is good. It can realize the control of the2D electro-hydraulic proportional directional valve. Secondly, if we choose appropriate frequency and amplitude of the flutter signal, the hysteresis of the2D electro-hydraulic proportional direction valve will be largely reduced and the static characteristics of the2D electro-hydraulic proportional direction valve will be improved to a great extent.The six chapter summarizes the major research work and the phase achievements, and gives some suggestions on the further development of the research work.