| With the advantages of good control performance,fast response and simple operation,the hydraulic valve-controlled system is widely used in various fields of hydraulic industry.However,because the traditional high-power hydraulic valve-controlled system usually uses a constant pressure supply,output power of the system and the power demanded by the load are severely mismatched,which results in huge throttling losses,leading to lower system transmission efficiency.Facing the energy crisis and the requirements of green manufacturing technology,the theme of energy saving and high efficiency has become one of the main issues of the development of hydraulic transmission systems.Aiming at the problem of low efficiency of high-power hydraulic valve-controlled systems,this paper proposes a new type of Multi-level Pressure Switching Control System(MPSCS)capable of realizing multi-level pressure output characteristics and having energy reserve and regulation capabilities,which dose not only enable real-time matching of changing load and a variety of working conditions,but also can dynamically adjust the energy globally,so that the system achieves the purpose of high efficiency and energy saving.Aiming at the characteristics and control strategies of the MPSCS,this paper focuses on the following research work:(1)Modeling and simulation of MPSCS.This paper presents the composition,basic working principle and pressure switching control strategy of the MPSCS,puts forward the pressure switching load matching control method based on the error judgment,establishes the system mathematical model and transfer function,lists the system state space equation,theoretically deduces the energy-saving effect of the system,analyzes the energy consumption characteristics of the system and determines the value of the intermediate pressure level of the system.Compared with the traditional single pressure supply system,the control and energy consumption performance of the MPSCS are simulated and analyzed.The research results show that the MPSCS can improve the matching state between the pressure required by the load and the input pressure of the system,thus it’s able to improve the energy transfer efficiency of the system.At the same time,the existing problems of the system are pointed out,which lays a foundation for the subsequent research work.(2)Parameter sensitivity analysis of MPSCS.Based on the state space equations of the MPSCS,the sensitivity equations with time-varying parameters are derived.Taking the step displacement command as the given signal of the MPSCS,and the sensitivity equations of the displacement response to each parameter of the system are solved.By defining the sensitivity indexes,the sensitivity histogram is obtained,and the parameter sensitivity of the MPSCS under different working conditions is quantitatively analyzed.(3)Impact suppression method of MPSCS.Based on the mathematical model and state space equation of the system,this paper analyzes the causes of the system impact,puts forward the impact suppression method based on feedforward pressure compensation from the perspective of reducing the influence of disturbance momentum on the system,and deduces the corresponding mathematical model of compensation link;From the perspective of improving the anti-interference ability of the system itself,a compensation control method of feedforward pressure compensation and impact suppression based on fuzzy PID is further proposed.The effectiveness of the above two methods is verified by simulation.(4)Research on control of multi-level pressure switching pressure regulation and control system.Aiming at the problem of energy accumulation of pressure level branches in the MPSCS,a multi-level pressure switching pressure regulation and control system is proposed to regulate the pressure of each pressure level branch in the system.This paper introduces the composition and working principle of the system,analyzes the pressure state of the system pressure level branches,puts forward the use rules of the pressure regulation unit and the method of parameter matching,and adopts the mechanism modeling method to establish the mathematical model of the components and the whole system of the pressure regulation and control system.The simulation results verify the control characteristics of the multi-level pressure switching pressure regulation and control system,which effectively improve the dynamic and static characteristics of the system.(5)Test system construction and performance analysis of the MPSCS.The test system is built to verify the effectiveness of the proposed MPSCS,parameter sensitivity analysis method,impact suppression method based on feedforward pressure compensation,composite control method of feed-forward pressure compensation impact suppression based on fuzzy PID and pressure regulation and control system control method. |
