| Compared with traction elevators,hydraulic elevators have the advantages of large load,high safety,low failure rate and small space utilization ratio.At present,most hydraulic elevators adopt two kinds of control modes: volume speed regulation and throttling speed regulation.But the main control valve of the elevator with throttling speed regulation mode mainly depends on the imported valve,which greatly increases the manufacturing cost of the system.In order to research the new hydraulic elevator system,to reduce the cost of the system,the team made a test platform of P-Q valve controlled hydraulic elevator itself.This system adopts a kind of throttling speed regulation mode which takes P-Q valve as elevator speed control valve.However,in the actual operation process,there is a large shock in the starting and stopping stage of the hydraulic elevator,which seriously affects the ride comfort.In view of the above problems existing in actual operation,this paper revolves around the main control valve proportional pressure flow compound valve,establishing the model of P-Q valve cylinder control system by using the modeling method of power bonding diagram and deriving the state equation according to the established power bond graph model,which explained the physical meaning of each component.Based on the mathematical model,the dynamic response of P-Q valve cylinder control system is analyzed in detail with the help of AMESim software.The flow curve of P-Q valve outlet is mainly compared with the inlet flow curve of plunger cylinder.According to the comparison of inlet pressure and outlet pressure of P-Q valve,the load-sensitive regulation characteristic of the valve is verified,which provides a certain theoretical basis for the research on the response of P-Q valve control system in common use.Hydraulic elevator is a typical speed control system.At present,most hydraulic elevators use closed loop PID control.The traditional feedback control methods of hydraulic elevator mainly include three types: rotor speed feedback control,hydraulic cylinder flow feedback control and car displacement feedback(speed feedback)control.In order to pursue better control mode,in this paper,based on PID closed loop control method,two ways of hydraulic cylinder flow feedback control and car displacement feedback control are modeled by AMESim software.The system pressure,flow rate and car velocity curves of the hydraulic elevator under the uplink and downlink conditions are also analyzed.Through comparative analysis,the control method using flow feedback is obviously better,but the lift car's downward control is still not ideal.Hydraulic elevator is a electro-hydraulic compound drive system with variable load,variable cavity and large inertia,the traditional PID control is difficult to effectively control the speed of hydraulic elevator.In order to solve this problem,the fuzzy PID controller is designed by using AMESim and MATLAB/simulink interface technology,and the system is modeled and simulated.The simulation results show that the hydraulic elevator system with straight top P-Q valve controlled by fuzzy PID control technology is stable in pressure,and the flow and velocity curves of the system are closer to the ideal velocity curve,which has certain theoretical significance for the stability control and speed optimization research of the hydraulic elevator with straight top.In order to provide data support for straight top P-Q valve-controlled hydraulic elevator,the overall scheme of measuring the key parameters of hydraulic elevator is put forward,the sensor and data acquisition card are selected in detail,and the measurement system for testing based on Labview is designed.The load sensitivity of P-Q valve is analyzed by measuring the inlet and outlet pressure of P-Q valve,the flow rate of P-Q valve outlet and the inlet flow rate of plunger cylinder are measured to provide data support for theoretical analysis in Chapter 3.Based on the paper,in order to solve the problem of starting and stopping oscillation in elevator operation process,a solution is put forward based on a detail study of the hydraulic elevator system with straight top P-Q valve control,and the comparative simulation analysis is carried out.A better speed control method is found,which provides a theoretical basis and reference for hydraulic elevator speed control. |
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