脉冲MIG焊全数字化控制系统研制
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摘要
随着工业自动化程度和焊接工艺要求的提高,弧焊电源的数字化控制已成为焊接领域的发展方向。脉冲MIG焊以其轴向性好、飞溅小、焊缝成形美观等特有的优点在焊接领域得到了广泛的应用。全数字化控制的弧焊电源具有灵活性好、控制精度高和响应速度快等特点,能极大提高脉冲MIG焊的控制水平。
本文首先对脉冲MIG焊的熔滴过渡行为进行了研究,分析了脉冲电流各参数的作用,并提出了对焊接电流和电压的双闭环控制方案。其中电流环采用变参数的数字PI控制,使得电流快速跟随给定;电压环采用平均电压闭环控制,实现电弧的稳定调节。
本文结合当前嵌入式技术和EDA技术发展的最新成果,选用ColdFireV2核微控制器MCF5213CAF80和FPGA EP1C6T144C8设计了脉冲MIG逆变电源的全数字化控制系统,搭建了该系统的硬件平台。其中MCF5213CAF80作为主控制器,负责电压环控制和焊接事务管理;FPGA作为协处理器,负责电流环的控制以及数字PWM模块的设计。两者通过在FPGA内部实现的并行总线接口进行数据的交换。
在研究脉宽调制工作机理的基础上,本文采用高速计数器法,利用VHDL语言在FPGA内部实现了数字PWM模块。较之采用专用PWM芯片设计的模拟PWM控制方式,数字PWM简化了控制系统与功率变换电路的接口,提高了系统的响应速度和稳定性。另外,本文将实时嵌入式操作系统μC/OS-Ⅱ移植到MCF5213CAF80中,各个任务可以进行独立设计,使得焊机的事务管理更加方便。
本文最后对所设计的全数字控制系统进行了测试,包括A/D转换精度测试、保护电路测试、PWM输出波形测试以及焊接过程波形控制效果测试。实验表明,该系统能够实现精确的电流波形控制和弧压闭环控制,为后续复杂的工艺研究和专家库的建立打下了坚实的基础。
With the development of industrial automation and welding process requirements, the digital control arc welding inverter power source has become the trend in welding field. Pulsed MIG welding is widely used for its characteristics of good direction transition, less material splash and nice welding appearance. Full-digital control arc welding inverter power source can greatly enhance the level of pulsed MIG welding for good flexibility, high control accuracy and quick system response.
At first, this paper studies the types of droplet transition in pulsed MIG welding, then analyzes the functions of the pulsed current parameters, finally proposes a dual-loop control method for welding current and welding voltage. Parameter-varying PI algorithm is applied to the current loop to adjust the welding current. The system uses the average welding voltage to keep the arc stable.
This paper has designed full-digital control system for pulsed MIG welding inverter power source by establishing hardware platform using ColdFire V2 core microcontroller MCF5213CAF80 and EP1C6T144C8. The main controller, MCF5213CAF80, is responsible for voltage-loop control and welding affairs management; and EP1C6T144C8, the coprocessor, realizes the current-loop control and digital PWM module. These two controllers communicate with each other through the parallel bus interface built in FPGA.
Based on the digital PWM mechanism, this paper introduces a High-Speed Counter Method to design the digital PWM module in FPGA implemented by VHDL. Compared with analog PWM mode using dedicated PWM chips, this method simplifies the interface between control circuits and power conversion circuits, as well as enhancing the system's security and stability. Furthermore, the portability of real-time embedded operating systemμC/OS-Ⅱon MCF5213CAF80 makes it possible to design tasks independently and more convenient to manage welding affairs.
Finally, this paper does some tests for the control system, including A/D conversion accuracy test, PWM output waveform test and control results test of welding process. Experiments prove that the system can control the current waveforms and average arc voltage precisely. The study helps to establish a solid foundation for subsequent complex research and expert system.
本文首先对脉冲MIG焊的熔滴过渡行为进行了研究,分析了脉冲电流各参数的作用,并提出了对焊接电流和电压的双闭环控制方案。其中电流环采用变参数的数字PI控制,使得电流快速跟随给定;电压环采用平均电压闭环控制,实现电弧的稳定调节。
本文结合当前嵌入式技术和EDA技术发展的最新成果,选用ColdFireV2核微控制器MCF5213CAF80和FPGA EP1C6T144C8设计了脉冲MIG逆变电源的全数字化控制系统,搭建了该系统的硬件平台。其中MCF5213CAF80作为主控制器,负责电压环控制和焊接事务管理;FPGA作为协处理器,负责电流环的控制以及数字PWM模块的设计。两者通过在FPGA内部实现的并行总线接口进行数据的交换。
在研究脉宽调制工作机理的基础上,本文采用高速计数器法,利用VHDL语言在FPGA内部实现了数字PWM模块。较之采用专用PWM芯片设计的模拟PWM控制方式,数字PWM简化了控制系统与功率变换电路的接口,提高了系统的响应速度和稳定性。另外,本文将实时嵌入式操作系统μC/OS-Ⅱ移植到MCF5213CAF80中,各个任务可以进行独立设计,使得焊机的事务管理更加方便。
本文最后对所设计的全数字控制系统进行了测试,包括A/D转换精度测试、保护电路测试、PWM输出波形测试以及焊接过程波形控制效果测试。实验表明,该系统能够实现精确的电流波形控制和弧压闭环控制,为后续复杂的工艺研究和专家库的建立打下了坚实的基础。
With the development of industrial automation and welding process requirements, the digital control arc welding inverter power source has become the trend in welding field. Pulsed MIG welding is widely used for its characteristics of good direction transition, less material splash and nice welding appearance. Full-digital control arc welding inverter power source can greatly enhance the level of pulsed MIG welding for good flexibility, high control accuracy and quick system response.
At first, this paper studies the types of droplet transition in pulsed MIG welding, then analyzes the functions of the pulsed current parameters, finally proposes a dual-loop control method for welding current and welding voltage. Parameter-varying PI algorithm is applied to the current loop to adjust the welding current. The system uses the average welding voltage to keep the arc stable.
This paper has designed full-digital control system for pulsed MIG welding inverter power source by establishing hardware platform using ColdFire V2 core microcontroller MCF5213CAF80 and EP1C6T144C8. The main controller, MCF5213CAF80, is responsible for voltage-loop control and welding affairs management; and EP1C6T144C8, the coprocessor, realizes the current-loop control and digital PWM module. These two controllers communicate with each other through the parallel bus interface built in FPGA.
Based on the digital PWM mechanism, this paper introduces a High-Speed Counter Method to design the digital PWM module in FPGA implemented by VHDL. Compared with analog PWM mode using dedicated PWM chips, this method simplifies the interface between control circuits and power conversion circuits, as well as enhancing the system's security and stability. Furthermore, the portability of real-time embedded operating systemμC/OS-Ⅱon MCF5213CAF80 makes it possible to design tasks independently and more convenient to manage welding affairs.
Finally, this paper does some tests for the control system, including A/D conversion accuracy test, PWM output waveform test and control results test of welding process. Experiments prove that the system can control the current waveforms and average arc voltage precisely. The study helps to establish a solid foundation for subsequent complex research and expert system.
引文
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[5]T.Maruyama,M.Okada,Y.Hida.Current waveform control in gas shielded arc welding for robotic systems[J].Research and Development,1993,43(1):27-30.
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[9]胡特生.电弧焊[M].北京:机械工业出版社,1994.
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[11]李峰,李亮玉,李香.国内全数字化焊机的研究现状[J].焊接技术,2006,35(4):6-8.
[12]M.Amin.Synergic Pulse MIG Welding[J].Metal Construction,1981,13(6):349-353.
[13]W.G.Essers,M.R.M.Van Gompel.Arc Control with Pulsed GMA Welding[J].Welding Journal,1984,63(6):26-32.
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[43]梁为民.微机应用系统的干扰与抗干扰技术[J].电子工程师,2001,27(6):30-31.
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[46]周华彬.混合信号DSP控制PMIG/DPMIG逆变焊机的研制[D].北京:北京工业大学,2005.
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[2]周志敏,周纪海,纪爱华.逆变电源实用技术[M].北京:中国电力出版社,2005.
[3]黄石生.弧焊电源及其数字化控制[M].北京:机械工业出版社,2006.
[4]H.Yamamoto,S.Harada,T.Ueyama.Improved current control makes inverters the power sources of choice[J].Welding Journal,1997,76(2):47-49.
[5]T.Maruyama,M.Okada,Y.Hida.Current waveform control in gas shielded arc welding for robotic systems[J].Research and Development,1993,43(1):27-30.
[6]郝伟.微机控制脉冲MIG焊接电源的研制[D].兰州:甘肃工业大学,2002.
[7]姜焕中.电弧焊与电渣焊[M].北京:机械工业出版社,1995.
[8]姜伟雁,张九海,赵崇仪.MIG(MAG)脉冲焊熔滴的过渡行为[J].焊接学报,1994,15(1):50-58.
[9]胡特生.电弧焊[M].北京:机械工业出版社,1994.
[10]柯利涛,黄石生,蒋东等.脉冲MIG焊逆变电源的研究现状[J].电焊机,2006,36(6):1-4.
[11]李峰,李亮玉,李香.国内全数字化焊机的研究现状[J].焊接技术,2006,35(4):6-8.
[12]M.Amin.Synergic Pulse MIG Welding[J].Metal Construction,1981,13(6):349-353.
[13]W.G.Essers,M.R.M.Van Gompel.Arc Control with Pulsed GMA Welding[J].Welding Journal,1984,63(6):26-32.
[14]吴开源,陆沛涛,李阳等.脉冲MIG焊控制的研究现状与展望[J].电焊机,2003,33(2):1-4.
[15]李正军编著.计算机测控系统设计与应用[M].北京:机械工业出版社, 2004.
[16]彭海燕,黄石生,蒋东等.脉冲MIG焊熔滴过渡控制的发展现状[J].焊接技术,2007,36(1):6-9.
[17]韩国明.焊接工艺理论与技术(第2版)[M].北京:机械工业出版社,2007.
[18]王伟明.逆变式GMA单脉冲和双脉冲焊机数字控制系统研究[D].北京:北京工业大学,2004.
[19]马德.数字控制铝合金双脉冲MIG焊工艺的研究[D].北京:北京工业大学,2004.
[20]李芳.全数字IGBT逆变脉冲MIG/MAG焊接电源的研究[D].兰州:兰州理工大学,2004.
[21]徐德进.微机控制多功能IGBT逆变焊机的研制[D].兰州:甘肃工业大学,2003.
[22]陈克选,朱艳红,李春旭等.基于双MCU的脉冲MIG焊数字化焊机[J].电焊机,2006,36(12):51-55.
[23]宋东风,胡绳荪,卢亚静.基于DSP的脉冲MIG焊数字化控制系统[J].电焊机,2006,36(2):48-51.
[24]阎涛,刘嘉,周华彬等.基于ADSP-21990的数字焊接电源研制[J].电焊机,2005,35(11):61-64.
[25]李晶皎,王爱侠,张广渊.ColdFire系列32位微处理器与嵌入式Linux应用[M].北京:北京航空航天大学出版社,2005.
[26]Freescale Semiconductor.CodeWarrior Development Studio Help System[EB/OL].http://www.freescale.com,2007.
[27]Unis Ltd.Processor Expert Help for CodeWarrior Plug-in for Freescale ColdFire[EB/OL].htttp://www.processorexpert.com,2007.
[28]Freescale Semiconductor.Expanding ColdFire Portfolio-Enabling Designs With Low Power and Connectivity[EB/OL].htttp://www.freescale.com,2007.
[29]Freescale Semiconductor.ColdFire-Embedded Controllers[EB/OL].http://www.freescale.com,2007.
[30]Freescale Semiconductor.68K/ColdFire V2 Core Architecture[EB/OL].http://www.freescale.com,2007.
[31]宋万杰,罗丰,吴顺君.CPLD技术及其应用[M].西安:西安电子科技大学出版社,1999.
[32]潘松,黄继业.EDA技术与VHDL(第2版)[M].北京:清华大学出版社,2007.
[33]李洪伟,袁斯华.基于Quartus Ⅱ的FPGA/CPLD设计[M].北京:电子工业出版社,2006.
[34]Freescale Semiconductor.MCF5213 ColdFire Integrated Microcontroller Reference Manual[EB/OL].http://www.freescale.com,2007.
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[36]王继红,王志鹏.磁珠在开关电源EMC设计中的应用[J].通信电源技术,2004,21(5):20-22.
[37]Altera Corporation.Cyclone Device Handbook,Volume 1[EB/OL].http://www.altera.com,2007.
[38]Altera Corporation.Cyclone EP1C6 Device Pin Information[EB/OL].http://www.altera.com,2003.
[39]Altera Corporation.USB-Blaster Download Cable User Guide[EB/OL].http://www.altera.com,2006.
[40]Analog Devices.AD7862-Simultaneous Sampling Dual 250kSPS 12-Bit ADC[EB/OL].http://www.analog.com/,1996.
[41]王瑞.电磁兼容技术在逆变弧焊机中的应用[J].电焊机,2001,31(3):41-42.
[42]白同云.电磁兼容设计[M].北京:北京邮电大学出版社,2001.
[43]梁为民.微机应用系统的干扰与抗干扰技术[J].电子工程师,2001,27(6):30-31.
[44]康军,赵伟.微机化仪器电磁兼容性设计[J].电测与仪表,2002,39(444):13-18.
[45]MarkImontrose,刘元安.电磁兼容和印刷电路板[M].北京:人民邮电 出版社,2002.
[46]周华彬.混合信号DSP控制PMIG/DPMIG逆变焊机的研制[D].北京:北京工业大学,2005.
[47]江思敏.VHDL数字电路及系统设计[M].北京:机械工业出版社,2006.
[48]刘瑞新.VHDL语言与FPGA设计[M].北京:机械工业出版社,2004.
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