Research And Design Of Load Control System For Temperature Stress Testing Machine Based On Fuzzy PI

With the continuous emergence of high-strength concrete,the temperature stress testing machine has a higher requirement for the load control system,such as the need for high position control accuracy,high pull pressure and deformation measurement accuracy.The research group developed the temperature stress testing machine in 2008.However,the load control system of the temperature stress testing machine cannot meet the requirements of high strength concrete crack test.With the support of Innovation in Hubei Province,a load control system with high precision position control for the temperature stress testing machine is researched to meet the requirements of high strength concrete crack test.The main work accomplished and the results in this study are as follows:(1)The scheme of load control system for Temperature Stress Testing Machine is designed.According to the new design requirements of the load control system,a higher technical index is put forward.In this paper,three-phase hybrid stepping motor is selected to be the implementing agencies of the load control system.On this basis,the scheme of load control system of temperature stress testing machine is put forward,including hardware scheme design and software scheme design.(2)A vector control strategy of three-phase hybrid stepping motor based on fuzzy PI control is proposed.The simulation research of stepping motor control system is completed.Vector control and space vector pulse width modulation are introduced into the driving control of three-phase hybrid stepping motor and three closed-loop position control system of three-phase hybrid stepping motor is built.The controller of each loop is designed,and the design of fuzzy PI controller is completed Finally,the simulation model is constructed by MATLAB/Simulink simulation tool,and the control effect of fuzzy PI and conventional PI is compared,and it is verified that the fuzzy PI controller has the characteristics of fast response and strong immunity.(3)Design of hardware and software for load control system of Temperature Stress Testing Machine is completed.The hardware design includes two parts: the main power circuit design and the control circuit design.The main power circuit is composed of two modules: rectifier and inverter.The control part consists of DSP chip,voltage and current sampling circuit,pressure and deformation sampling circuit,protection circuit,speed and position detection circuit.The slave computer software consists of DSP main program,Timer T1 interrupt program design,fuzzy PI program,SVPWM program,protection interrupt program.Vector control and space vector pulse width modulation are introduced into the driving control of three-phase hybrid stepping motor,which improves the running characteristics of three-phase hybrid stepping motor and improves the dynamic and static performance of the load control system.The fuzzy PI controller is used as the position loop controller of the load control system to improve the positioning accuracy of the load control system and meet the design requirements of the current temperature stress testing machine.