Pump controlled motor electrohydraulic servo systems are much used in circumstances where high power drive is needed. This kind of system has the advantage of energy-saving. But, it also has some defects that have to ...Pump controlled motor electrohydraulic servo systems are much used in circumstances where high power drive is needed. This kind of system has the advantage of energy-saving. But, it also has some defects that have to be improved. Microcomputer control of a pump controlled motor electrohydraulic servo system is studied. A PID controller is first adopted on the closed loop control system, and experimental results are obtained. Then, a model reference adaptive controller is designed and realised on the same system applying a single board microcomputer. Experimental results show that the dynamic properties of the adaptive control system is much better than those of the PID system under different inertia load conditions.展开更多
Conventional vacuum control in a milking system is accomplished by using a vacuum pump, sized for the maximum air flows into the milking system, running at a full speed. The difference between the pump capacity and th...Conventional vacuum control in a milking system is accomplished by using a vacuum pump, sized for the maximum air flows into the milking system, running at a full speed. The difference between the pump capacity and the necessary flow of air is compensated by allowing air to enter the system through a regulator. The solution presented in this paper uses a VFD （variable frequency driver） in order to drive the vacuum pump at a controlled speed, so that the air removed equals the air entering the milking system. The VFD technology is able to adjust the rate of air removal from the milking system, by changing the speed of the vacuum pump motor. The VFD is controlled by a computer using a virtual instrument in order to emulate a PID （proportion integration differentiation） regulator. The tests aimed to evaluate the vacuum regulator characteristics and vacuum stability. A statistical analysis of the experimental results was performed and it showed that there was a significant difference between the experimental results obtained for the two methods of vacuum regulation （with vacuum regulator and VFD controller respectively）. The experimental results proved that the used of the VFD controller led to a higher vacuum stability in terms of the error between the set vacuum value and the achieved values.展开更多
With the rapid development of the global economy,more and more attention has been paid to the energy conservation of construction machinery.The hydraulic system is the key component of construction machinery,and impro...With the rapid development of the global economy,more and more attention has been paid to the energy conservation of construction machinery.The hydraulic system is the key component of construction machinery,and improving its energy utilization rate has become an important means to achieve energy conservation.In conventional valve-controlled or pump-controlled hydraulic systems of construction machinery,controllability and energy-saving performance typically cannot be considered at the same time.The pump-valve coordinated system combines the energy-saving characteristics of the pump-controlled system and the high-precision and high-frequency response of the valve-controlled system,which has the potential to become a primary research direction of electro-hydraulic systems.This review summarizes the recent research progress in energy-saving technologies based on pump-valve coordinated systems.Particularly,we discuss the structures of hydraulic systems in different categories of construction machinery,various control methods of the electro-hydraulic system,novel hydraulic hybrid energy regeneration systems,and key components.In addition,future directions and challenges of the pump-valve coordinated systems are described,such as independent metering system(IMS),common pressure rail(CPR),and hybrid power source(HPS).展开更多
基金The Project Supported by Doctoral Programme Foundation of Institution of Higher Education
文摘Pump controlled motor electrohydraulic servo systems are much used in circumstances where high power drive is needed. This kind of system has the advantage of energy-saving. But, it also has some defects that have to be improved. Microcomputer control of a pump controlled motor electrohydraulic servo system is studied. A PID controller is first adopted on the closed loop control system, and experimental results are obtained. Then, a model reference adaptive controller is designed and realised on the same system applying a single board microcomputer. Experimental results show that the dynamic properties of the adaptive control system is much better than those of the PID system under different inertia load conditions.
文摘Conventional vacuum control in a milking system is accomplished by using a vacuum pump, sized for the maximum air flows into the milking system, running at a full speed. The difference between the pump capacity and the necessary flow of air is compensated by allowing air to enter the system through a regulator. The solution presented in this paper uses a VFD （variable frequency driver） in order to drive the vacuum pump at a controlled speed, so that the air removed equals the air entering the milking system. The VFD technology is able to adjust the rate of air removal from the milking system, by changing the speed of the vacuum pump motor. The VFD is controlled by a computer using a virtual instrument in order to emulate a PID （proportion integration differentiation） regulator. The tests aimed to evaluate the vacuum regulator characteristics and vacuum stability. A statistical analysis of the experimental results was performed and it showed that there was a significant difference between the experimental results obtained for the two methods of vacuum regulation （with vacuum regulator and VFD controller respectively）. The experimental results proved that the used of the VFD controller led to a higher vacuum stability in terms of the error between the set vacuum value and the achieved values.
基金Project supported by the Zhejiang Provincial Natural Science Foundation of China(No.LR19E050002)the National Key R&D Program of China(No.2019YFB2004604)+2 种基金the National Natural Science Foundation of China(Nos.51821093 and 51708493)the Key R&D Program of Zhejiang Province(Nos.2018C01020 and 2018C01060)the Youth Funds of the State Key Laboratory of Fluid Power and Mechatronic Systems(No.SKLoFP_QN_1804),China。
文摘With the rapid development of the global economy,more and more attention has been paid to the energy conservation of construction machinery.The hydraulic system is the key component of construction machinery,and improving its energy utilization rate has become an important means to achieve energy conservation.In conventional valve-controlled or pump-controlled hydraulic systems of construction machinery,controllability and energy-saving performance typically cannot be considered at the same time.The pump-valve coordinated system combines the energy-saving characteristics of the pump-controlled system and the high-precision and high-frequency response of the valve-controlled system,which has the potential to become a primary research direction of electro-hydraulic systems.This review summarizes the recent research progress in energy-saving technologies based on pump-valve coordinated systems.Particularly,we discuss the structures of hydraulic systems in different categories of construction machinery,various control methods of the electro-hydraulic system,novel hydraulic hybrid energy regeneration systems,and key components.In addition,future directions and challenges of the pump-valve coordinated systems are described,such as independent metering system(IMS),common pressure rail(CPR),and hybrid power source(HPS).
