D+A组合控制多泵源液压系统泵阀复合控制研究

针对传统大功率多泵液压阀控系统中由于泵源输出与负载流量需求不匹配，导致液压系统传动效率低下的问题，在数字泵PCM控制概念的基础上提出一种基于数字+模拟（D+A）组合控制多泵源液压系统。通过流量区域划分方法，给出该系统的构型原则，其中定量泵组排量比采用二进制编码，由1台变量泵补偿定量泵的阶跃流量差值；建立多泵源液压系统流量状态矩阵，通过求解得到泵组的控制信号；为了减少阶跃流量冲击对系统控制特性的影响，提出多泵源液压系统泵阀复合控制策略，并对该系统输出特性进行试验研究。试验结果表明在泵阀复合控制策略下，多泵源液压系统具有良好的动静态特性和节能效果。正弦位置跟随精度达到±0.1 mm，滞后约为100 ms；由于采用D+A组合流量控制和比例溢流阀压力控制，始终使多泵源液压系统输出的流量和压力分别高于负载所需要流量10 L/min和压力2 MPa，使该系统的溢流和节流损失大大降低。

Pump-valve Compound Control Performance of D+A Combined Multi-pump Controlled System

Due to the mismatch between the pump output and the load flow demand in the traditional high-power multi-pump hydraulic valve controlled system, the hydraulic system transmission efficiency is low. Based on the concept of PCM control of digital pump, a hydraulic control system combined with digital and analog control is proposed. Through the flow area division method, the configuration principle of this system is given, in which the fixed pumps' displacement ratio uses a binary-coding, and the step flow difference of the fixed pump is compensated by 1 variable pump. The flow state matrix of this system is established, and the control signals of pumps are obtained through solving this matrix. In order to reduce the control characteristics impact of the system due to the step flow, a pump-valve compound control strategy is proposed, and the output characteristics of the system are tested under this control strategy. The results show that under this control strategy, the multi-pump hydraulic system has good dynamic and static characteristics, as well as an energy saving effect. The sinusoidal displacement tracking accuracy is up to ±0.1 mm with a lag of approximately 100 ms. Due to the use of D+A combined flow control and proportional relief valve pressure control, the output flow and pressure of the multi-pump hydraulic system are always higher than the load required flow of 10 L/min and the load required pressure of 2 MPa, respectively. So that the overflow and throttle losses of the system are greatly reduced.