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Variable frequency hydraulic technology is a new type of energy-efficient drive technology, the motor speed control is applied to the product of the hydraulic system, rely on to change the frequency of the power supply can be achieved to adjust the speed of the implementing agencies, the motor is always in the state of high-efficiency to improve the traditional hydraulic power the drive energy utilization is not high, the lower the efficiency of the whole system, is an energy-efficient technologies from the power source. A wide range of variable frequency hydraulic technology applications, has a wide range of applications in machine tools, hydraulic machinery, injection molding machines and other mechanical equipment, the promotion will save a lot of energy in China. Variable frequency hydraulic technology is not very mature, slow to respond to problems such as dynamic, low-speed characteristics, speed accuracy is difficult to guarantee such issues, and therefore need further research. Design and development, a variable frequency hydraulic station prototype, using a variable speed motor with dosing pumps instead of the traditional fixed-speed motor and variable pump drive mode, both to achieve energy saving, but also eliminates the need for complex variable displacement structure; system requirements, PLC inverter induction motor control. Combined with technical indicators, component selection and assembly of inverter prototype hydraulic station, a mathematical model of the variable frequency hydraulic station, and the establishment of a simulation model based on MATLAB7.0. This paper, adaptive fuzzy PID control algorithm to improve the dynamic response of slow speed and low accuracy for variable frequency hydraulic station. First, conventional PID control parameters tuning with the empirical formula of the Ziegler-Nichols method, with MATLAB7.0 on the basis of the mathematical model of the system simulation, the simulation results show that the system steady-state error is small, but there are larger overshoot and a longer period of adjustment time. Not lose stability accuracy in order to obtain a better dynamic characteristics, combination of fuzzy control to adjust short time the advantages of non-steady-state error and PID, fuzzy-PID control, function switch in deviation when using fuzzy control deviation smaller when using PID control. The simulation results show that the fuzzy-PID control effectively solve the existing problems of the conventional PID control, but due to the rigid switching fuzzy control and PID control, stable output fluctuations before, another fuzzy control quantization factors and the scale factor is not adjustable, you can not substantial changes to adapt to the object, and poor robustness. To this end, this paper designed based on fuzzy rules switch and adjustable variable domain of quantification factor and the scale factor based adaptive fuzzy PID controller, the simulation results show that the control system has good dynamic characteristics and steady-state performance, solve two fluctuations in the control mode switching.
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