变频液压站控制系统设计
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摘要
变频液压技术是一种新型节能传动技术,是将电机变频调速应用于液压系统的产物,依靠改变供电电源的频率就可实现对执行机构的速度调节,电机始终处在高效率的工作状态,改善了传统液压动力传动能量利用率不高,整机系统效率较低的问题,是一种从动力源头节能的技术。变频液压技术的应用也十分广泛,在机床、液压机械、注塑机等许多机械设备中都有广泛的应用,其推广将为我国节约大量能源。目前变频液压系统的技术还不是很成熟,存在诸如动态响应慢、低速特性差、调速精度不易保证等问题,因此仍需进一步研究。
本文设计开发了一台变频液压站样机,采用变速电机与定量泵替代传统定速电机与变量泵的驱动模式,既实现了节能,又省去复杂的变排量结构；针对系统要求,采用PLC+变频器+异步电动机的控制方式。结合技术指标,对变频液压站样机进行了元件选型和组装,建立了变频液压站的数学模型,并基于MATLAB7.0建立了仿真模型。
针对变频液压站动态响应慢、调速精度低的问题,本文通过自适应模糊PID控制算法进行改善。首先采用常规PID控制,参数用Ziegler-Nichols经验公式法整定得到,在系统数学模型的基础上用MATLAB7.0进行仿真,仿真结果表明系统稳态误差小,但存在较大超调和较长的调整时间。为了获得较好的动态特性并不失稳定精度,本文结合模糊控制调整时间短和PID无稳态误差的优点,采用模糊-PID控制,通过开关切换函数,在偏差较大时采用模糊控制,偏差较小时采用PID控制。仿真结果表明模糊-PID控制有效的解决了常规PID控制存在的问题,但由于模糊控制和PID控制的刚性切换,输出稳定之前存在波动,另外模糊控制的量化因子和比例因子是不可调的,不能适应对象的大幅度变化,鲁棒性欠佳。为此,本文设计了基于模糊规则切换和基于变论域量化因子和比例因子可调的自适应模糊PID控制器,仿真结果表明控制系统获得了良好的动态特性和稳态性能,解决了两种控制方式切换时产生的波动。
The variable frequency control hydraulic technology is a new kind of energy saving transmission technique. It is formed while the variable frequency variable speed applied to the hydraulic system. It changes actuating element speed through changing the power supply frequency. By this way, the motor is always in high efficiency. Energy is saved from the source. This technology improves the low energy efficiency of traditional hydraulic power transmission and low efficiency of the whole system. The application of variable frequency control hydraulic technology is widely applied in mechanical equipment, such as machine tools, hydraulic machines, and injection molding machines and so on. So its marketing will saves a lot of energy for our country. Now the technology of Variable Frequency Hydraulic System is not mature. There are some problems for further research, such as slow dynamic response, poor low speed characteristics, and low speed accuracy.
A prototype of variable frequency hydraulic Station was designed and built. It uses variable speed motor and fixed displacement pump to drive actuating element instead of using traditional pattern with fixed-speed motor and variable displacement pump. It not only achieves energy conservation, but also omits the complex changing displacement organization. To meet the system requirements, PLC is adopted to control it. According to technical indicators, we built the prototype of variable frequency hydraulic Station with appropriate components. Then the mathematic model is founded and the simulation model is founded based on MATLAB7.0.
To solve the problem of slow dynamic response and low speed accuracy, different control algorithms are used to improve the problem. First, conventional PID control is used in the system and the parameters are obtained by the Ziegler-Nichols empirical formula. Then simulation is carried on based on the mathematical model with MATLAB 7.0. Simulation results show that there is low steady-state error, but larger overshoot and long adjustment time in the system. In order to obtain good dynamic characteristic and the accuracy properties are not lost, fuzzy-PID control is used, which combines the advantages of fuzzy control and PID control. When the deviation is large, fuzzy control is worked. When the deviation is small PID control is worked. The two controllers switch through the switching function. Simulation result shows that the fuzzy-PID controller effectively reduces the adjustment time. But the simulation curve fluctuates before the stability output because of the rigid switch pattern. Besides quantization factors and scaling factor of fuzzy control are not adjustable, so the system cannot adapt the great changes of controlled object and has poor robustness. Thus, the self-adaptive fuzzy-PID control is designed and implemented. It is based on fuzzy switching arithmetic and the online self-tuning arithmetic with quantized and proportional factors. The simulation results show that the control system has good dynamic and static performances. It solves fluctuations generated by the switch of two control mode.
本文设计开发了一台变频液压站样机,采用变速电机与定量泵替代传统定速电机与变量泵的驱动模式,既实现了节能,又省去复杂的变排量结构；针对系统要求,采用PLC+变频器+异步电动机的控制方式。结合技术指标,对变频液压站样机进行了元件选型和组装,建立了变频液压站的数学模型,并基于MATLAB7.0建立了仿真模型。
针对变频液压站动态响应慢、调速精度低的问题,本文通过自适应模糊PID控制算法进行改善。首先采用常规PID控制,参数用Ziegler-Nichols经验公式法整定得到,在系统数学模型的基础上用MATLAB7.0进行仿真,仿真结果表明系统稳态误差小,但存在较大超调和较长的调整时间。为了获得较好的动态特性并不失稳定精度,本文结合模糊控制调整时间短和PID无稳态误差的优点,采用模糊-PID控制,通过开关切换函数,在偏差较大时采用模糊控制,偏差较小时采用PID控制。仿真结果表明模糊-PID控制有效的解决了常规PID控制存在的问题,但由于模糊控制和PID控制的刚性切换,输出稳定之前存在波动,另外模糊控制的量化因子和比例因子是不可调的,不能适应对象的大幅度变化,鲁棒性欠佳。为此,本文设计了基于模糊规则切换和基于变论域量化因子和比例因子可调的自适应模糊PID控制器,仿真结果表明控制系统获得了良好的动态特性和稳态性能,解决了两种控制方式切换时产生的波动。
The variable frequency control hydraulic technology is a new kind of energy saving transmission technique. It is formed while the variable frequency variable speed applied to the hydraulic system. It changes actuating element speed through changing the power supply frequency. By this way, the motor is always in high efficiency. Energy is saved from the source. This technology improves the low energy efficiency of traditional hydraulic power transmission and low efficiency of the whole system. The application of variable frequency control hydraulic technology is widely applied in mechanical equipment, such as machine tools, hydraulic machines, and injection molding machines and so on. So its marketing will saves a lot of energy for our country. Now the technology of Variable Frequency Hydraulic System is not mature. There are some problems for further research, such as slow dynamic response, poor low speed characteristics, and low speed accuracy.
A prototype of variable frequency hydraulic Station was designed and built. It uses variable speed motor and fixed displacement pump to drive actuating element instead of using traditional pattern with fixed-speed motor and variable displacement pump. It not only achieves energy conservation, but also omits the complex changing displacement organization. To meet the system requirements, PLC is adopted to control it. According to technical indicators, we built the prototype of variable frequency hydraulic Station with appropriate components. Then the mathematic model is founded and the simulation model is founded based on MATLAB7.0.
To solve the problem of slow dynamic response and low speed accuracy, different control algorithms are used to improve the problem. First, conventional PID control is used in the system and the parameters are obtained by the Ziegler-Nichols empirical formula. Then simulation is carried on based on the mathematical model with MATLAB 7.0. Simulation results show that there is low steady-state error, but larger overshoot and long adjustment time in the system. In order to obtain good dynamic characteristic and the accuracy properties are not lost, fuzzy-PID control is used, which combines the advantages of fuzzy control and PID control. When the deviation is large, fuzzy control is worked. When the deviation is small PID control is worked. The two controllers switch through the switching function. Simulation result shows that the fuzzy-PID controller effectively reduces the adjustment time. But the simulation curve fluctuates before the stability output because of the rigid switch pattern. Besides quantization factors and scaling factor of fuzzy control are not adjustable, so the system cannot adapt the great changes of controlled object and has poor robustness. Thus, the self-adaptive fuzzy-PID control is designed and implemented. It is based on fuzzy switching arithmetic and the online self-tuning arithmetic with quantized and proportional factors. The simulation results show that the control system has good dynamic and static performances. It solves fluctuations generated by the switch of two control mode.
引文
[1]MURRENHOFF H液压控制技术发展趋势(Ⅰ)[J].工程设计,1997,3：20-29
[2]金春花,韩东熙.液压系统效率的分析与对策.液压与气动,1999(5)：19-22
[3]AZMEIER B K, FELDMAN D G. Arbeitsbereich Konstruktionstechnik I. Electro-hydrostatic low power linear drive-system performance and controls to minimize power consumption. In:Proceedings of the3rd International Symposium on Fluid Power Transmission and Control. Beijing:International Academic,1997:113-119
[4]MANASEK R. Simulation of an electro-hydraulic load-sensing system with AC motor and frequency changer [A].Proceedings of thelst FPNI-PhD Symposium[C]. Slovakia:Slovak University of Technology,2000:311-324
[5]彭天好,徐兵,杨华勇.变频液压技术的发展及研究综述[J].浙江大学学报(工学版),2004,38(2)：215-221
[6]徐兵,杨华勇,变频驱动液压电梯控制系统综述[J],中国机械工程,2001,12(9)：1082-1086
[7]权龙,李凤兰.注塑机电液控制系统节能原理及最新技术[J].机床与液压,1999,5：6-7
[8]张健民,杨华勇,路甬祥.能量回馈式VVVF液压电梯速度控制系统研究[J],机械工程学报,2000,36(7)：61-65
[9]翁正飞.变频与电液比例技术复合调速系统及其应用.液压气动与密封,2004,(1)：21-23
[10]HERKOMMER R. Ways towards energy saving in hydraulic steering systems [A].3rd International Fluid Power Conference[C]. Aachen:Shaker Verlag,2002:465-474.
[11]王世明,李天石.交流变频容积调速回路的特性与速度控制.机床与液压,1999,(5)：22-23
[12]Jun-Koo Kang, Seung-Ki Sul. Vertical-Vibration Control of Elevator Using Estimated Car Acceleration Feedback Compensation, IEEE Transactions on Industrial Electronics, 47(1):91-99
[13]KAZUO Nakano, YUTAKA Tanaka. Energy saving type electro-hydraulic servo system [J].Journal of Fluid Control,1988,18(3):35-51
[14]YAMAMOTOI Tomoichiro. Apparatus for controlling a hydraulic elevator [P]. United States Patent:US4593792,1986-10
[15]WU H-W, LEE C-B. Self-tuning adaptive speed control of a pump/inverter-controlled hydraulic motor system [J].Journal of Systems&Control Engineering,1995,209(2): 101-114
[16]DANIEL S. Closed-loop electronic valving and the application of variable voltage variable frequency in hydraulics [J].Elevator World,1999,47(9):66-72
[17]HELBIG A. Injection moulding machine with electric hydrostatic drives [A].3rd International Fluid Power Conference[C]. Aachen:Shaker Verlag,2002:67-82
[18]SHIMOAKI Motoo. VVVF-controlled hydraulic elevators [J].Mitsubishi Electric Advance, 1992,61(12):13-15
[19]BERINGER A G. The frequency-controlled hydraulic drive [J].Elevator World,1998,46(2): 94-96
[20]Lu Yongxiang, Historical progress and prospects of fluid power transmission and control. Proceedings of the 5th International Conference on Fluid power Transmission and Control. Zhejiang University. PR. China,2001:62-68
[21]黎勉,罗勇武,查晓春,等.交流变频调速在液压系统中的应用[J].机床与液压,1997,6：15-16
[22]侯继伟.深海极端海洋环境模拟平台电液比例压力控制技术研究[D].浙江大学,2005
[23]路甬祥.流体传动与控制技术的历史进展与展望.机械工程学报,2001(37)：1-10
[24]黄昕.液压系统的节能措施[J].贵州工业大学学报(自然科学版),2001,30(4)
[25]BERINGER A G. The frequency-controlled hydraulic drive [J].Elevator World,1998,46(2): 94-96
[26]Kuang Ronghua, Rong TaiPing. A Simple Fuzzy Controller with an Adaptive PID parameter. Journal of Hua Zhong University of Science and Technology.2001,9(6):25-30
[27]DANIEL S. Closed-loop electronic valving and the application of variable voltage variable frequency in hydraulics [J].Elevator World,1999,47(9):66-72.
[28]徐兵,采用蓄能器的液压电梯变频节能控制系统研究[D].杭州：浙江大学,2001
[29]K. Grotenburg, F.Koch, I. Erlieh. Modeling and dynamic simulation of variable speed pump storage units incorporated into the German electric power system. EPE Trondheim, 2001,8(1):67-77
[30]王彩霞.模糊变频恒压控制系统的研究：[硕士学位论文].长春：长春理工大学,2002
[31]方彦军,胡静.燃油泵变频控制系统的设计与实现[J].华东电力,2003,31(12)：48-50.
[32]王吉龙.基于变频技术的液压调速系统控制方案的仿真研究：[硕士学位论文].大连：大连海事大学,2006
[33]黄镇海.液压伺服位置系统的智能控制：[硕士学位论文].秦皇岛：燕山大学
[34]HELBIG A. Injection moulding machine with electric-hydrostatic drives [A].3rd International Fluid Power Conference[C]. Aachen:Shaker Verlag,2002:67-82.
[35]HELBIG A. Injection moulding machine with electric-hydrostatic drives [A].3rd International Fluid Power Conference[C]. Aachen:Shaker Verlag,2002:67-82.
[36]林建杰.液压电梯闭式回路节能型电液控制系统研究：[博士学位论文].杭州：浙江大学,2005
[37]史志永.基于交流变频技术的变量泵.液压与气动,2003,(1)：38-41
[38]彭勇刚,洪杰.变频控制在注塑机控制器中的应用.机电工程,2002,19.(6)：21-23
[39]蔡军,曹慧英.基于PLC模糊控制的调速系统研究[J].微计算机信息(测控自动化), 2008,24(9-1)：56-57.
[40]赵文峰Matlab控制系统设计与仿真.西安电子科技大学出版社,2002.
[41]纪志成,薛花,沈艳霞.基于Matlab交流异步电机矢量控制系统的仿真建模[J].系统仿真学报,2004,16(3)：384-389.
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[46]刘金琨.先进PID控制及MATLAB仿真[M].电子工业出版社,2003.
[47]Huang Y, Yasunobu S. A General Practical Design Method for Fuzzy PID Control from Conventional PID Control [J]. Fuzzy Systems,2005(2):969-972.
[48]王立新,王迎军.模糊系统与模糊控制.北京：清华大学出版社,2003：233-253
[49]马金祥,余发山,等.一种模糊自适应PID控制器的设计与仿真.焦作工学院学报(自然科学版),2002(3)：197-200
[50]黄成静.基于模糊逻辑工具箱的控制系统.计算机仿真,2003(2)：75-78
[51]吴晓莉,林哲辉,等MATLAB辅助模糊系统设计.西安：西安电子科技大学出版社,2002.50-56
[52]陈祥彬.基于模糊PID控制和变频调速的高速液压拉伸机控制系统研究.机械与电子,2002,(1)：40-42
[2]金春花,韩东熙.液压系统效率的分析与对策.液压与气动,1999(5)：19-22
[3]AZMEIER B K, FELDMAN D G. Arbeitsbereich Konstruktionstechnik I. Electro-hydrostatic low power linear drive-system performance and controls to minimize power consumption. In:Proceedings of the3rd International Symposium on Fluid Power Transmission and Control. Beijing:International Academic,1997:113-119
[4]MANASEK R. Simulation of an electro-hydraulic load-sensing system with AC motor and frequency changer [A].Proceedings of thelst FPNI-PhD Symposium[C]. Slovakia:Slovak University of Technology,2000:311-324
[5]彭天好,徐兵,杨华勇.变频液压技术的发展及研究综述[J].浙江大学学报(工学版),2004,38(2)：215-221
[6]徐兵,杨华勇,变频驱动液压电梯控制系统综述[J],中国机械工程,2001,12(9)：1082-1086
[7]权龙,李凤兰.注塑机电液控制系统节能原理及最新技术[J].机床与液压,1999,5：6-7
[8]张健民,杨华勇,路甬祥.能量回馈式VVVF液压电梯速度控制系统研究[J],机械工程学报,2000,36(7)：61-65
[9]翁正飞.变频与电液比例技术复合调速系统及其应用.液压气动与密封,2004,(1)：21-23
[10]HERKOMMER R. Ways towards energy saving in hydraulic steering systems [A].3rd International Fluid Power Conference[C]. Aachen:Shaker Verlag,2002:465-474.
[11]王世明,李天石.交流变频容积调速回路的特性与速度控制.机床与液压,1999,(5)：22-23
[12]Jun-Koo Kang, Seung-Ki Sul. Vertical-Vibration Control of Elevator Using Estimated Car Acceleration Feedback Compensation, IEEE Transactions on Industrial Electronics, 47(1):91-99
[13]KAZUO Nakano, YUTAKA Tanaka. Energy saving type electro-hydraulic servo system [J].Journal of Fluid Control,1988,18(3):35-51
[14]YAMAMOTOI Tomoichiro. Apparatus for controlling a hydraulic elevator [P]. United States Patent:US4593792,1986-10
[15]WU H-W, LEE C-B. Self-tuning adaptive speed control of a pump/inverter-controlled hydraulic motor system [J].Journal of Systems&Control Engineering,1995,209(2): 101-114
[16]DANIEL S. Closed-loop electronic valving and the application of variable voltage variable frequency in hydraulics [J].Elevator World,1999,47(9):66-72
[17]HELBIG A. Injection moulding machine with electric hydrostatic drives [A].3rd International Fluid Power Conference[C]. Aachen:Shaker Verlag,2002:67-82
[18]SHIMOAKI Motoo. VVVF-controlled hydraulic elevators [J].Mitsubishi Electric Advance, 1992,61(12):13-15
[19]BERINGER A G. The frequency-controlled hydraulic drive [J].Elevator World,1998,46(2): 94-96
[20]Lu Yongxiang, Historical progress and prospects of fluid power transmission and control. Proceedings of the 5th International Conference on Fluid power Transmission and Control. Zhejiang University. PR. China,2001:62-68
[21]黎勉,罗勇武,查晓春,等.交流变频调速在液压系统中的应用[J].机床与液压,1997,6：15-16
[22]侯继伟.深海极端海洋环境模拟平台电液比例压力控制技术研究[D].浙江大学,2005
[23]路甬祥.流体传动与控制技术的历史进展与展望.机械工程学报,2001(37)：1-10
[24]黄昕.液压系统的节能措施[J].贵州工业大学学报(自然科学版),2001,30(4)
[25]BERINGER A G. The frequency-controlled hydraulic drive [J].Elevator World,1998,46(2): 94-96
[26]Kuang Ronghua, Rong TaiPing. A Simple Fuzzy Controller with an Adaptive PID parameter. Journal of Hua Zhong University of Science and Technology.2001,9(6):25-30
[27]DANIEL S. Closed-loop electronic valving and the application of variable voltage variable frequency in hydraulics [J].Elevator World,1999,47(9):66-72.
[28]徐兵,采用蓄能器的液压电梯变频节能控制系统研究[D].杭州：浙江大学,2001
[29]K. Grotenburg, F.Koch, I. Erlieh. Modeling and dynamic simulation of variable speed pump storage units incorporated into the German electric power system. EPE Trondheim, 2001,8(1):67-77
[30]王彩霞.模糊变频恒压控制系统的研究：[硕士学位论文].长春：长春理工大学,2002
[31]方彦军,胡静.燃油泵变频控制系统的设计与实现[J].华东电力,2003,31(12)：48-50.
[32]王吉龙.基于变频技术的液压调速系统控制方案的仿真研究：[硕士学位论文].大连：大连海事大学,2006
[33]黄镇海.液压伺服位置系统的智能控制：[硕士学位论文].秦皇岛：燕山大学
[34]HELBIG A. Injection moulding machine with electric-hydrostatic drives [A].3rd International Fluid Power Conference[C]. Aachen:Shaker Verlag,2002:67-82.
[35]HELBIG A. Injection moulding machine with electric-hydrostatic drives [A].3rd International Fluid Power Conference[C]. Aachen:Shaker Verlag,2002:67-82.
[36]林建杰.液压电梯闭式回路节能型电液控制系统研究：[博士学位论文].杭州：浙江大学,2005
[37]史志永.基于交流变频技术的变量泵.液压与气动,2003,(1)：38-41
[38]彭勇刚,洪杰.变频控制在注塑机控制器中的应用.机电工程,2002,19.(6)：21-23
[39]蔡军,曹慧英.基于PLC模糊控制的调速系统研究[J].微计算机信息(测控自动化), 2008,24(9-1)：56-57.
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