压电式高速开关阀控液压缸位置系统

针对开关阀控液压缸位置分辨率低、响应慢的问题，设计了压电式高速开关阀控液压缸位置系统。首先，建立开关阀控液压缸位置系统模型，分析了PWM载波频率对开关阀流量特性的影响规律，采用基于差动流量的双阀结构，实现液压缸负载流量的非线性补偿，减小开关阀死区对系统静、动态性能的影响。然后，分析双阀控制式液压缸系统负载脉冲流量的影响因素，得到了开关阀控液压缸位置抖振的产生机理，比较基于脉冲流量的PWM、PAM、PFM控制方法。最后，依据压电式高速开关阀流量特性，提出了PWM+PAM的复合控制方法，根据误差信号及其变化，调节占空比和流量幅值，实现液压缸位置的快速、精确控制。仿真及实验结果表明:系统定位精度将近1%，为高速开关阀及其控制系统应用提供了理论基础。 

Hydraulic cylinder position system controlled by piezoelectric high-speed on-off valve

Aimed at low position resolution and slow response of on-off valve controlled cylinder, a hydraulic cylinder position system controlled by piezoelectric high-speed on-off valve was designed. Firstly, the position system model of on-off valve was built in order to analyze the influence of PWM carrier frequency on the on-off valve flow characteristics. The system structure based on differential flow of double valve is adopted to realize the nonlinear compensation of hydraulic cylinder load flow, which reduced the influence of dead zone on the static and dynamic performance. Then, mechanism and principle of on-off valve controlled hydraulic cylinder position chattering are obtained by analyzing the influence factors of load pulse flow of double valve controlled hydraulic cylinder system, and PWM, PAM and PFM control methods based on the pulse flow are compared.Finally, considering the piezoelectric high-speed on-off valve flow characteristics, a composite control method with PWM and PAM is proposed, which helps the system realize fast and accurate position control by adjusting the duty cycle and flow amplitude according to the error signal and change. Simulation and experimental results show that the positioning accuracy is nearly 1%, which provides a theoretical basis for the application of high-speed on-off valve and control system.