2011•Journal of Zhejiang University(Engineering Science)Requires access
Oil temperature control of large hydraulic system
Gong Bin
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Abstract
A temperature control system was proposed employing proportional valve to regulate cooling water flow through a plate heat exchanger in order to retain the constant oil temperature in a large hydraulic system.Characterizing large time delay,the mathematic model of temperature variation was conducted based on laws of thermodynamics.The conventional PID control algorithm was compared with the fuzzy PID by using Matlab/Simulink.Simulation results show that the fuzzy PID strategy is independent on system model,and can efficiently improve the performance,which is easily realized with PLC.Fuzzy PID strategy was employed in the real system.Results show that the fuzzy PID controller can reach control accuracy of 45±1 ℃ under variant working conditions,which is irrespective of time delay problem and parameter variations.Compared with conventional PID controller,the fuzzy PID controller can achieve higher control accuracy,faster response and stronger robustness in oil temperature control of large hydraulic system.