【作者】 卢红影；

【导师】 姜继海；

【作者基本信息】 哈尔滨工业大学 ， 机械电子工程， 2008， 博士

【摘要】 液压变压器是在液压传动中能够实现压力转换的一种液压元件。它相当于压力转换器,通过液压变压器可以使液压执行元件(定量液压马达、液压缸)从压力耦联的液压恒压网络系统中无节流损失地获取能量。液压变压器的出现扩大了二次调节静液传动系统的应用领域。二次调节静液传动系统的工作原理决定了其负载端应该是变量执行元件。在驱动直线负载工况下,由于液压缸的活塞面积难以变化,所以在工程上常采用液压阀来进行控制,这种控制方法引入了节流损失且系统效率低,这使传统型液压变压器的应用受到了限制。对于解决该问题比较合适的方案是采用新型液压变压器来进行控制,即没有理论上的节流损失,又能够进行能量的回收与利用,为提高液压系统的效率提供了一条非常有效的途径,因此开展对新型液压变压器的研究具有十分重要的意义。在查阅大量国内外有关文献的基础上,综述了国内外液压变压器的研究现状及发展趋势,分析了液压变压器的特点,阐述了液压变压器的关键技术及研究现状,对液压变压器的应用范围作了介绍,针对目前手动型液压变压器变压频率低以及变压精度的局限性,研制出电控斜轴柱塞式液压变压器。依据液压变压器的工作原理,对液压变压器的特性进行了分析,建立了液压变压器流量、转矩和变压比的公式,为液压变压器的结构设计及仿真分析提供了理论依据。电控斜轴柱塞式液压变压器驱动的直线负载系统由三大子系统组成,即计算机控制系统、交流同步电机伺服调速系统以及液压变压器控制液压缸动力机构,分别建立了三大子系统的数学模型。为便于分析液压变压器的工作原理,提出了液压变压器平衡角的定义,并建立了液压变压器平衡角的公式。结合三大子系统的数学模型,建立了液压变压器控制角的数学模型以及液压变压器驱动直线负载系统的数学模型。为满足新型伺服系统的需求,采用机械结构优化设计的方法,完成电控斜轴柱塞式液压变压器的设计以及装配和调试,研制出可实现变压比范围为[0,2]的电控斜轴柱塞式液压变压器原理样机。结合“负负载”的概念,分析液压变压器四个象限工作的特性,并对液压变压器“负载驱动”和“驱动负载”工况下,液压变压器驱动直线负载系统中液压恒压网络系统压力、液压蓄能器流量、液压变压器控制角、能量回收和再利用效率进行了仿真和实验研究,结果表明液压变压器驱动直线负载系统具有回收和再利用负载重力势能的能力。针对液压变压器本身的复杂非线性特性,提出采用模糊自适应整定PID控制策略,并针对液压变压器驱动直线负载位置伺服系统进行仿真与实验研究。结果证明该策略能较好地补偿液压变压器的非线性特性,并可提高系统的抗负载干扰能力和系统响应的快速性。采用研制的电控斜轴柱塞式液压变压器,搭建液压变压器驱动直线负载系统的实验台,完成实验台硬件电路设计和控制软件的编程工作。在该实验台上对液压变压器的基本性能进行测试,以及分别采用PID、模糊自适应整定PID控制策略对液压变压器系统进行实验研究。实验结果表明所阐述理论正确,采用的控制策略合理可行,研制的液压变压器驱动直线负载系统实验样机是成功的。更多还原

【Abstract】 Hydraulic transformer is an important unit which can transform pressure in hydraulic transmission. It corresponds to a hydraulic pressure transformer, by which hydraulic performance unit (fixed displacement hydraulic motor and hydraulic cylinder)can gain energy without throttling losses from hydraulic constant pressure rail system. The hydraulic transformer expands the application scope of secondary regulation of hydrostatic transmission. The working principle of secondary regulation of hydrostatic transmission determines that its load must be variable unit. For the piston area of hydraulic cylinder can’t be varied, hydraulic valves are usually adopted to this system. Not only this method brings throttling loss but also causes low efficiency. As a result, the application of traditional hydraulic transformer is restraint. An optimum method to solve this problem is to adopt new hydraulic transformer, which has the advantages not only without throttling losses but also recuperation and reuse energy. It also provides with an effective method to improve the efficiency of hydraulic constant pressure rail system. So it has great valve to research on the new hydraulic transformer.After synthesizing numerous related literatures and reference materials at home and abroad, this research not only summarizes the current study status and development trend of hydraulic transformer and analyses the characteristics of the hydraulic transformer, but also expatiates on the key technology and study status of the hydraulic transformer. It also introduces the applications of the hydraulic transformer. For the low transformation and the limited transformation scope of manual operating new hydraulic transformer, the electric control bent axial piston hydraulic transformer is developed.According to the working principle of hydraulic transformer, the characteristic of hydraulic transformer is analyzed and deduced the formula of flow, torque and pressure transformation factor, which provide with theoretical basis for hydraulic transformer construction design and simulation analysis.The electric control bent axial piston hydraulic transformer driving linear system consists of three subsystems which are computer control system, alternating synchronous servo motor system and hydraulic transformer controlling hydraulic cylinder power mechanism. This study also builds mathematical models of the three subsystems.In order to analyze the working principle of the hydraulic transformer, the balance angle of hydraulic transformer is defined and built its formula. Combining with the mathematical models of three subsystems, the mathematical model of hydraulic transformer control angle is built and the hydraulic transformer driving linear load system mathematical model is also built.In order to meet the demand of new servo system, adopting optimum design method to mechanism construction, the mechanism construction design of electric control bent axial piston hydraulic transformer is completed. Also the assembly and debug of the hydraulic transformer is done. As a result the electric control bent axial piston hydraulic transformer is developed which transformation factor scope is from zero to two.By introduction“driving load”to analyze on hydraulic transformer four-quardant characteristics, simulation and experiment study are made including pressure of hydraulic constant pressure rail system, flow of hydraulic accumulator, control angle of hydraulic transformer and efficiency of energy recuperation and reuse under working condition of hydraulic transformer“load driving”and“driving load”in driving linear load system. In view of the complex nonlinear characteristic of new servo hydraulic transformer, the fuzzy adaptive tuning PID control strategy is applied to the experiment system. Simulation study is done on the new servo hydraulic transformer driving linear load position servo system. Simulation results prove that application of the fuzzy adaptive tuning PID control strategy can compensate the nonlinear characteristic of the hydraulic transformer and improve the resistibility of load disturbance and the ability of fast response to the system.Based on the developed electric control bent axial piston hydraulic transformer prototype, the hydraulic transformer driving linear load system experiment test-bed, the hardware circuit design for the system and the computer control system are built. And the control software is programmed to control the experiment prototype. Not only the characteristic of the developed hydraulic transformer is tested by experiment but also the two control strategies including PID and fuzzy adaptive tuning PID are applied to the system. The experiment result shows that not only the expatiated theory is correct and the adopted control strategy is feasible but also the prototype of hydraulic transformer driving linear system for hydraulic constant pressure rail system is successful.更多还原