Study On Dynamic Characteristics Of Hydraulic System Of Double Hoist

Whether it is water control,shipping locks,power plants,flood control must be used to gate,and the opening and closing of the gate to use a special mechanical device-hoist.Compared with Windlass type hoist of bulky and same capacity,the weight of the hydraulic hoist is much lighter,and simple layout of hydraulic structure,we can save a lot of investment.Especially in the case of a large number of orifice,the advantage is more obvious.Due to smooth operation,the system can easily realize stepless speed regulation,automatic overload protection,easy to connect with computer,intelligent control and so on,hydraulic hoist shows its obvious superiority.But,hydraulic hoist as the main direction of the gate opening and closing at the same time,it is also faced with the system dynamic performance is not ideal,the system synchronization accuracy is not high,poor stability of the balance loop,and many other problems to be solved.Therefore,this article embarks from the question,a new synchronous circuit structure is adopted to complete the design of control strategy and improve the dynamic performance of the system and the stability of the balance loop.First of all,this paper briefly introduces the working principle,research status and main problems of hydraulic system of hoist,and expounds the research background and significance of this paper.In the second chapter,the working principle of the system key element A11 VO proportional variable pump and the FD type one-way throttle balance valve are described in detail.Based on the transfer function method,the mathematical models of the two key components are established.The influence of the main structural parameters on the dynamic characteristics of the system is analyzed.Based on the open-loop gain,a feasible method to improve the stability of the system is proposed.The third chapter makes a brief introduction to the hydraulic system simulation software AMESim.The two core components of the synchronous circuit and the balance circuit are established by using the HCD Library: the A11 VO proportional variable pump and the simulation model of FD type one-way throttle valve.The accuracy of the model is verified,and the method to restrain the pressure shock of the proportional pump outlet,to stabilize the pressure,to improve the stability of the system and to speed up the adjustment time of the balance circuit system is obtained.In the fourth chapter,the function of the PID control algorithm and the parameter tuning method are introduced in detail.The AMESim simulation model of hydraulic system of hoist is built.The PID controller is designed based on the system model.valve and test curve were analyzed,it is concluded that the buffer overflow valve type can reduce the pressure of the hydraulic rotary motor,to improve its operating performance,so as to improve the service life of the system of hydraulic components.After the introduction of the PID controller in the system,the simulation results show that the system can achieve more accurate displacement following the step load and 1 cylinder step speed.Observe the control effect and dynamic performance of PID controller.The fifth chapter introduces the working principle of feedforward compensation controller,in the case of load disturbance,PID control effect is not very ideal,the feedforward compensation control strategy to eliminate the disturbance caused by load change.The transfer function block diagram of the synchronous circuit module of the hoist hydraulic system is established.The simulation results show that,under the same bias load disturbance,the feed forward PID control has obvious improvement compared with the PID control.