降压型开关液压源工作稳定性及其节能研究

【作者】 张晓峰；

【导师】 顾临怡；

【作者基本信息】 浙江大学 ， 机械电子控制工程， 2004， 硕士

【摘要】 多执行器特性是液压系统的一大特点。在大功率的工作系统中，提高液压系统的效率对于节能和节约成本是很重要的。目前的多执行器系统主要有：节流调速系统，负载敏感系统，二次调节系统，但均存在各种缺陷。 本世纪初提出的开关液压源系统可以实现在升压及降压过程中增加流量的需要，因而可以很好的适应负载的要求，是一种全新原理的节能型液压系统。作为一种压力转换装置，开关液压源可以很好地适应负载。 本文首先针对降压型开关液压源工作的稳定性问题，提出在降压型开关液压源中引入回油背压，避免系统中出现气蚀现象，提高系统工作的稳定性；其次分析带回油背压的降压型开关液压源的能耗组成，通过仿真与试验，研究负载、开关频率以及系统效率三者之间的关系；最终提出降压增流型开关液压源回油背压控制策略及其工程实现方案，达到最佳节能效果。 第一章综述在液压传动与控制系统中，具有负载适应能力的各种控制回路：压力适应回路、流量适应回路和功率适应回路，以及这些系统的优缺点；介绍新近提出的开关液压源概念及存在的问题。 第二章针对降压型开关液压源存在的气蚀现象，在降压型开关液压源结构中引入背压阀，提高系统工作的稳定性，分析带回油背压的降压增流刑开关液压源的工作原理，并对带回油背压的降压型开关液压源结构中各个元件进行建模，分析系统的动态特性。 第三章主要分析带回油背压的降压型开关液压源的能耗组成，研究背压，负载以及开关频率对系统效率的影响效果，通过仿真及试验，重点分析开关频率对带回油背压的降压型开关液压源效率的影响。 第四章根据能耗分析，针对带回油背压的降压型开关液压源的能耗特性，确定系统能耗的目标函数，通过优化背压以及开关频率这三个参数以使目标函数最小。 第五章总结全文更多还原

【Abstract】 A practical advantage of hydraulic systems is their multiple-actuator characteristic. At present, there are three kinds of multiple-actuators hydraulic systems: throttle control system, load sensing system and secondary regulation system. But there is disadvantage in each system.The switchmode hydraulic power supply, which was put forward recently, can realize the adaptation to the load of every actuator, by adjusting the supplied pressure. Through the control of PWM signal, the switchmode hydraulic power supply can output proper pressure, which is adaptive to the load. As a new theory, there are still some problems of switchmode hydraulic power supply. Switchmode hydraulic power supply can adapt to the load, but in the course of pressure buck and pressure boost, the efficiency still needs to be improved. And there is cavitation in the pressure buck switchmode hydraulic power supply.At first, this article solves the problem of the stability in the pressure buck switchmode hydraulic power supply, through introducing the return pressure into the pressure buck switchmode hydraulic power supply. Secondly, constitute of the energy loss, in the pressure buck switchmode hydraulic power supply with the return pressure, is analyzed, and it researches the relation between the frequency of the switch and the efficiency of the system, through the simulation and the; experiment. Finally, we put forward the control policy of the switch frequency and the return pressure, in order to get the optimal efficiency of the system.In chapter 1, the article summarizes all kinds of hydraulic systems, which can adapt the load, and the shortcoming of these systems. Next, the conceptionof switchmode hydraulic power supply and the limitation of this system are introduced.In chapter 2, aiming at the cavitation in the pressure buck switchmode hydraulic power supply, the relief valve is introduced in order to improve the stability of this system. In this chapter, the principle of the pressure buck switchmode hydraulic power supply with return pressure is also illuminated, and each component’s mathematical modeling is built in order to analyze the dynamic characteristic.In chapter 3, constitute of the energy loss, in the pressure buck switchmode hydraulic power supply with the return pressure, is analyzed. And we lay emphasis on analyzing the influence of switch frequency to the efficiency.In chapter 4, on the basis of the constitute of energy loss, the objective of energy loss is established. We minimize the objective, through optimizing the return pressure and switch frequency.In chapter 5, conclusion.更多还原