The Study Of The Controller For Large Flow 2D Digital Servo Valve

Electro-hydraulic servo control system due to fast response, high control precision, high power to weight ratio, etc. are widely used in aerospace, machine tools, mining, shipbuilding and other practical systems applications。In the hydraulic control system, the servo-valve due to its power amplification and signal conversion effectation,plays a key role in the performance of the entire hydraulic system。Throughout the development of the entire hydraulic systerm is inseparable from the development of the servo valve, so how to improve the performance of the servo valve, especially the large flow servo valve performance which is rapidly developed in recent years is always a major issue in the electro-hydraulic control field. With the advancement of technology digital control of the servo valve are more and more attentioned. Thelarge flow 2D servo valve due to the unique mechanical of double freedom of movement, compared to other servo valve has a strong anti-pollution, good dynamic performance, a small amount of zero leakage, simple structure, etc. Therefore, This paper conduct research to the digital control of the high flow 2D servo valve. Research contents and results are as follows:1. This paper investigates the working principle of the 2D digital servo valve, and mechanism design. in order to improve the flow of the pilot control level and 2D valve frequency response,designs the chute and high-trough groove as the pilot stage, and make the pilot stage and power level as whole of the 2D valve, then achieve spool two degrees of freedom movement. While establishing a mathematical model of the large flow 2D servo, lay the foundation to achieve the control of the 2D servo valve.2. Structural analysis for the electric-mechanical converter of the high flow 2D servo---three-phase Induction synchronous motor. Studied the several common working ways of the three-phase Induction synchronous motor and the continuous tracking control algorithm is proposed due to the contradictory of response and accuracy in the hydraulic system. While establishing a mathematical model of the three-phase induction synchronous motor, lay the foundation to achieve the control of the step motor.3. For the three-phase induction synchronous motor, using the maximum torque control method id=0 and combining space vector modulation algorithm(SVPWM), while using the three series closed-loop —current, speed, rotor angular position to achieve the precise control. Establishing a mathematical model of the id=0 method, and simulation combined with Simulink. Simulation results show that the mathematical model of the three-phase induction synchronous motors has good characteristics, Its frequency width is about 150 Hz approximately at-3dB and-90°, rising time of step response is only about 12 ms.4. Based on space vector modulation algorithms and continuous tracking control algorithm the large flow 2D servo valve controller is designed which take TMS320F2812 as the core and experiment of static and dynamic characteristics of electro-mechanical converter is performed. The experimental results illustrate that the electro-mechanical converter has excellent static and dynamic characteristics whose repeatability is less than 3%, linearity is less than 1.5%, frequency width is approximately 120 Hz at-3dB and-90°,and rising time of step response is about 15 ms.5. The test rig for performance of 2D servo valve is built. The experiments of No load flow characteristic curve, null position leakage characteristics, dynamic characteristic of 2D servo valve are performed. The experimental results reveal that the 2D digital servo valve has good performance. Its frequency width is about 100 Hz approximately at-3dB and-90°, rising time of step response is only about 17 ms, the overshoot of maximum percentage is about 8%.