Research On Fuzzy Control Method For Constant Flow Of Variable Speed Hydraulic Power Source

With the development of variable frequency motor speed regulation technology, variable speed pump-controlled hydraulic power system emerges in industrial applications gradually. It changes the motor speeds by the variable frequency motor speed regulation technology, since the motor is connected by the shaft coupling with the pump, the input speed of the pump is changing, as the displacement of the gear pump is a definite number, the output flow of the pump varies as the speed linearly, achieving the purpose of the hydraulic motor’s speed control. Although the variable speed hydraulic pump- controlled system has the advantages of simple structure, wide speed range, reliability, energy saving and environmental protection, easy to implement precise closed-loop control, it shows a great potential in the large load and power conditions of high flow and inertia systems. While the load conditions change rapidly, due to the strong coupling characteristic of flow and pressure when the load changes, the flow controlling is instability, the static and dynamic response and steady-state accuracy of the system is low, using the traditional PID control method is not conducive to achieve good control effect, therefore, it has a high research value to improve the static and dynamic response of the system from the perspective of the control methods.In this paper, we focus on the research of fuzzy control in the precise flow control of variable speed hydraulic power systems in different typical conditions, experimental results show that fuzzy control can achieve precise flow control of variable speed hydraulic power source, the same with PID control, it has a better steady-state accuracy and is more suitable for applications where load dramatic changes. The main studies are as follows:1.According to the characteristics of variable speed hydraulic power system, at the request of constant flow control of the power source, using MATLAB simulation software to study PID control and fuzzy control of the system in various typical conditions, get the simulation results and comprehensive evaluation of the two methods;2.Described the hardware and software components of variable speed pump-controlled hydraulic power systems in detail, complete the control program of the system based on the platform of LabVIEW8.6;3.Done the flow control experiments of the permanent magnet motor-driven hydraulic power source in typical conditions based on virtual instrument control platform, to conduct a comprehensive evaluation of dynamic characteristics and steady state accuracy under different control strategies.4.Make the motor speed as the controlled object directly, programming to realize the fuzzy control of the motor speed in the variable speed pump-controlled motor system, demonstrated the feasibility of fuzzy control in the precise control of motor speed.