【作者】 丁海港；

【导师】 赵继云；

【作者基本信息】 中国矿业大学 ， 机械电子工程， 2014， 博士

【摘要】 传统的液压马达调速系统有两种基本形式：阀控和泵控。阀控响应快但效率低，适用于对快速性要求较高的中小功率场合；泵控效率高但响应慢，适用于大功率和对快速性要求不高的场合。近年来，阀-泵联合控制得到了迅速发展，其充分发挥了阀控与泵控各自的优势。论文提出了一种崭新的阀-泵并联控制系统，即阀-泵并联变结构调速系统，在调速过程中控制模式随控制要求而变，可实现大功率液压调速系统的综合性能，即低速平稳快速启停、快速调节负载干扰、全程高效率。论文的主要工作和研究成果如下：（1）总结和分析了国内外目前阀-泵联合控制系统的工作原理和特点，并指出目前的阀-泵联合控制方式难以实现上述综合性能。（2）设计了阀-泵并联变结构调速系统，其关键点有两点，一是阀可以根据控制要求处于补油或泄油两种状态，以使系统处于补油或泄油式阀-泵并联两种控制模式，二是可以通过改变Kvp，调节阀控与泵控在速度控制中的比重；建立了阀-泵并联变结构调速系统的数学模型，分析了系统的参数，并指出传统的泵控系统加入阀控后，液压固有频率不变，但总泄漏系数明显增大，导致系统阻尼比显著增大且随阀的工作点（阀开口及系统压力）而变化，同时导致系统刚度下降，易受负载干扰。（3）设计了开式以及闭式阀-泵并联变结构控制系统的结构，建立了补油式和泄油式阀-泵并联控制闭式系统的流量平衡方程，分析了各流量之间的关系，指出在闭式阀-泵并联变结构调速系统中，补油回路及冲洗回路是必需的，不能因有阀控补油就取消补油回路，同时冲洗回路除了有热交换的作用还有平衡系统流量的作用。建立了液压模拟系统与实际系统之间参数匹配的理论基础，指出为模拟实际系统的动态特性，应分别按照泵排量、马达排量、转动惯量三个参数来配置模拟系统，本实验系统是以煤矿液压提升机这种大功率大惯量液压系统为例而建立的模拟系统。（4）提出了阀控权重Kv和泵控权重Kp的概念，并依据不同的Kv和Kp，建立了传统泵控、阀控与阀-泵并联控制之间的联系；为了判别阀与泵在联合调速中的作用，建立了阀-泵权重比的概念，即Kvp=Kv:Kp，并通过该权重比以及阀控状态，判别系统处于何种控制模式。（5）提出了补油式和泄油式阀-泵并联两种控制模式，研究了不同权重比对控制特性的影响，并获得了阀-泵并联控制的规律：在不同的权重比（Kvp=1:0～0:1）下，系统响应速度呈金字塔形，两头慢（阀控和泵控），中间快（阀-泵并联控制），因此无论对于指令信号，还是负载干扰的快速响应，阀-泵并联控制比单独泵控或阀控响应都快；因阀控的开环增益大于泵控，对于相同的权重之和（Kv+Kp），以阀控为主的系统响应快于以泵控为主；阀与泵的流量之比与阀-泵权重比成正比；补油式比泄油式阀-泵并联控制更具优势，因为前者使系统的阻尼比更稳定，这有利于系统的预测与控制，并且还可通过提高Ps，进一步提高响应速度和增大速度刚度，更适用于对负载干扰的快速调节，仿真与实验结果表明，此处取Kvp=1:0.2较合适。（6）研究了不同控制模式下大惯量系统的低速特性。泄油式阀控或泄油式并联阀控通过增加可控的泄漏，增大系统的阻尼比，以增强低速平稳性，而且由阀控泄漏引起的阻尼比的增加，可补偿因摩擦负斜率（Stribeck效应）引起的阻尼比的下降，进一步增强了系统的低速稳定性。阀初始电压对提高低速特性至关重要，建立了阀初始电压的理论公式，并研究了不同油温，不同开口对系统低速特性的影响，获得了泄油式阀控在启停低速阶段的控制规律，同时实验表明，只要阀初始电压设置在理论值附近，均能获得满意的低速特性，这使泄油式阀控具有操作性和实用性，且此处取Kvp=1:0.1较合适。（7）建立了阀-泵并联变结构调速系统的AMEsim仿真模型以及基于虚拟仪器技术的实验系统，研究了一个调速周期内的阀-泵并联变结构调速特性。仿真与实验结果表明，在调速过程中，不同控制模式之间切换平滑连续，阀和泵的工作状态符合预期；通过改变不同调速阶段的控制模式，实现了大功率液压马达调速系统的综合性能，即在低速段采用泄油式并联阀控，实现了大惯量的平稳快速启停，在高速段采用补油式并联阀控，实现了对负载干扰的快速调节，在加速和减速段泵提供主要流量，充分了发挥泵控的高效的优势。阀-泵并联变结构控制，利用阀控及泵控双通道，建立了控制结构(模式)依控制要求而变的灵活的控制机制，通过改变阀-泵权重比，使阀控与泵控协调工作，充分发挥了阀控、泵控各自的优势，丰富了液压系统的调速方式，使电液控制系统更具灵活性和适应性，可实现大功率液压调速系统的综合性能，如低速平稳快速启停、快速调节负载干扰、全程高效率。更多还原

【Abstract】 Traditional hydraulic motor speed servos have two basic types: valve control andpump control. The valve control system responds fast to valve and load inputs, but isless efficient, so this arrangement is only suitable to applications required rapidresponse with low power. The pump control system is more efficient since both flowand pressure are closely matched with load requirement, but responds slowly，so thisarrangement is only suitable to the applications required high power with slowresponse. Recently, the valve-pump combination control is rapidly developing, whichallows full play to advantages of valve control and pump control. This paper proposeda totally new valve-pump parallel control system, that is valve-pump parallel variablestructure control systems for motor speed servo with large power. Control mode willvary with control requirement during speed regulation process, and the proposedsystem will achieve comprehensive performance for hydraulic motor speed systemwith large power, such as low-speed performance, rapid response to load variation andhigh efficiency.Main work and achievements are as following:(1) Overview the principle and feature of valve-pump combination systems, andpoint out those existing valve-pump combination systems cannot achieve abovecomprehensive performance.(2) Design the valve-pump parallel variable structure control systems, and there aretwo key points, one is that the control valve can work at leaking status andreplenishing status, and then the system can be under leaking valve-pump parallelcontrol mode and replenishing valve-pump parallel control mode; the other is toregulate effect of valve and pump control by varying Kvp; establish the mathematicalmodels of the proposed system under different control modes, analyze systemparameters, which indicate that the system natural frequency doesn’t change, whenintroducing valve control into traditional pump control system, but total leakingcoefficients and damping ratios become greater and vary widely with operating points(valve opening and load pressure), and which will decrease velocity stiffness andmake system more susceptible to disturbances.(3) Design the structure of open circle system and closed circle system invalve-pump parallel variable structure control, establish balance flow equations ofclosed circle system under the replenishing valve-pump parallel control (RVPC) mode and leaking valve-pump parallel control (LVPC) mode, then analyze the relationshipof different flow, and point out that in the closed circle system of the valve-pumpparallel variable structure control, both the replenishing circuit and flushing circuit arenecessary, and replenishing circuit should not be canceled because of the exiting ofthe replenishing controlled by the valve, and the flushing circuit has the function ofbalancing system flow besides heat exchanging. Establish the foundation of parametermatching between hydraulic simulation systems and practical systems，and point outthat to simulate the practical system, should configure the simulation systemaccording to pump displacement, hydraulic motor displacement and inertia,respectively. The test system is established according to a hydraulic hoist unsed incoal, which is a kind of hydraulic system with high power and high inertia.(4) Propose the concept of valve weight（Kv） and pump weight（Kp）, establishthe relationship of traditional control method (valve control and pump control) andvalve-pump parallel control; Propose the concept of valve-pump weight ratio, that isKvp=Kv:Kp, to judge which mode plays a leading role in control process and whichcontrol mode is in.(5) Establish RVPC and LVPC modes, and study the influence of different Kvponsystem dynamic performance, and obtain some laws of valve-pump parallel control:the response is pyramidal when Kvp=1:0～0:1, and is slow at two sides (valve controland pump control) and rapid at middle (valve-pump parallel control), so thevalve-pump parallel control responds faster than single valve control and pumpcontrol both for input singal and load disturbance; the system mainly controlled valveresponds faster than that mainly controlled pump for the same sum of Kvand Kp,because open loop gain of valve control is greater than that of pump control; the ratioof valve and pump flow is proportional to Kvp; compared with the leaking valve-pumpparallel, the replenishing valve-pump parallel control has more advantages, becausethe latter can make damping ratio more stable, which contributes system predictionand control, in addition it can further improve response and velocity stiffness byraising Ps, and is more suitable to achieve rapid response to load disturbance.Simulation and experiment show that Kvp=1:0.2is preferable.(6) Study low velocity performance under different modes. Leaking valve controland leaking parallel valve control obtain good low velocity performance by increasingcontrollable leakages to increase damping ratios. Moreover, the increase of dampingratios caused by leakage controlled by the valve just compensates the reduction of damping ratios due to the friction negative slop (Stribeck effect), which furtherenhances low velocity performance. The valve initial voltage is essential to lowvelocity performance, and then is proposed. Study the influence of different initialvoltages and temperatures on low velocity performance. The experiment results showa sound low velocity performance could be obtained, if the initial voltage is set aroundthe theoretical value, which makes leaking parallel valve control more practical ataspect of improving low velocity performance.(7) Establish a simulation mode on AMEsim platform and set up a test system onLabView platform by virtual instrument technology, and study dynamic performanceof valve-pump variable structure control in a duty circle. Both simulation andexperiment results show that comprehensive performance is achieved by changingcontrol modes in control process, the leaking parallel valve control mode is applied tostart and stop stages and improves low velocity performance, the replenishing parallelvalve control mode is applied to the uniform stage with high speed and achieves fastresponse to load disturbance, the parallel pump control mode is applied to accelerationand deceleration stages and makes full use of its high efficiency; control modes switchsmoothly and both the variations of valve and pump are continuous and matchprevious supposition.In all, the valve-pump parallel variable mode control establishes a flexible controlmechanism by using two channels of valve control and pump control, where controlmodes vary with control requirement, which make the valve coordinate the pump, andmake full use of advantages of valve control and pump control, and enriches thecontrol modes of hydraulic speed regulation systems, and makes electro-hydraulicsystems more flexible and suitable, and could achieve comprehensive performance ofhydraulic speed regulation systems with large power, such as low-speed performance,rapid response to load variation and high efficiency.更多还原