单片机控制逆变埋弧焊机系统设计

【作者】 吴荣；

【导师】 李鹤岐；

【作者基本信息】 兰州理工大学 ， 材料加工工程， 2004， 硕士

【摘要】 本文首先介绍了埋弧自动焊的特点、发展历史、目前国内外的研究现状。接着阐述微机技术与逆变技术相结合在焊接领域中的深远影响，并针对传统埋弧焊机体积大、控制电路复杂、可靠性差等问题，提出了采用单片机控制IGBT逆变埋弧焊机的研究方向。本论文主要介绍了所研制的单片机控制逆变埋弧焊机的组成结构和控制原理。分别就电源主电路、脉宽调制电路、驱动电路、保护电路、显示电路以及送丝和小车行走电路做了详细的分析，并从软硬件两个方面给予了系统的阐述。逆变电路选取IGBT为主控开关功率转换器件，采用输出功率较大的全桥式逆变结构，配以高频变压器和输出电抗器组成了本系统的主电路系统，讨论了高频变压器的设计要点，IGBT的特性与使用时的注意事项，并对IGBT、整流二极管等关键元件采取了阻容保护性措施：控制电路以16位高性能单片机80C196KC为核心，对整个埋弧焊系统进行控制，文中采用脉宽调制方法来控制焊机的输出外特性，脉宽调制信号由PWM专用芯片SG3525组成的脉宽调制电路产生，焊接过程中单片机实时采样焊接电流和电压，并与预置值进行比较，其偏差经单片机PI离散运算后输出相应的控制量来调节PWM芯片的输出脉宽，进而调整输出电流，以此来达到控制焊机外特性的目的。针对常用的SCR-M调速系统存在调节范围窄、线性度差等缺点，本文设计了脉宽调制型送丝和小车调速系统，送丝系统的PWM脉冲由PWM专用芯片SG3524产生，应用电弧电压反馈的变速送丝调节原理，采用PI控制算法，实现了送丝速度的闭环控制，通过对送丝速度的调节保持电弧电压的稳定。小车行走机构的PWM脉冲直接由单片机的HSO 0产生，小车行走速度的调节采用开环控制。本文还详细阐述了单片机外围电路的功能、作用等，并针对可能出现的过流、过热、过压／欠压等故障，设计了相应的保护电路。系统软件采用模块化设计方案，文中详细介绍了程序结构以及各子程序模块的功能和设计，并且针对埋弧焊多任务控制特点，通过软件优化设计，合理协调了各控制任务。在焊机的主电路、控制电路和软件部分都进行了可靠性与抗干扰设计，系统分析了可能影响焊机正常工作的各种干扰及其产生原因，并在原理图设计、PCB制作以及程序编制的过程中采取了相应的硬件、软件抗干扰措施。本文对埋弧焊控制系统的实施方案、组成部分进行了调试分析，得到了初步的结果，并给出了在试验过程中记录的数据与相关波形，调试结果表明：所设计的埋弧焊控制系统电路简单，控制精度高，抗干扰能力强，人机对话明了，操作方便，工作稳定可靠，能够满足逆变埋弧自动焊电源与过程控制的要求，提高了焊机的综合性能及自动化程度。另外，针对本焊机的后续研究工作提出了进一步完善的建议。最后，在单电源单丝埋弧焊的基础上，结合几种双(多)丝埋弧焊方法的特点，提出了双电源串列双丝埋弧焊系统的设计方案，为以后进一步研究高效化埋弧焊奠定了一定的基础。更多还原

【Abstract】 The application, history, actuality and foreground of SAW-tech are firstly introduced in the introduction part of this paper. The far-reaching affects of micro-chip technique combined with inverter technique on the development of welding machine are follow set forth. According to the shortcomings of traditional SAW, a direction of studying on microprocessor control IGBT inverter for submerged arc welding is put forward.The component parts and control principle of pulsed SAW inverter power source are mainly introduced in the paper. The main circuit, pulse width modulation circuit, drive circuit, safeguard circuit as well as wire feeding and tractor circuits are respectively analyzed. Hard ware and soft ware are both expatiated systematically.The main circuit is made up of rectifier, filter, high-frequency transformer, output reactor, and full-bridge inverter, where 4 IGBT are adopted. The key points in designing high-frequency transformer, as well as the characteristics of IGBT are discussed. At the same time, in order to obtain accurate and real-time control, high performance 16-bit microprocessor 80C196KC is adopted for control kernel. In the power source, a PWM technology and the current feedback PI algorithm is used to adjust the output volt-ampere characteristic of power source. The digital signal from microprocessor are firstly converted into analogy signal, which is then modulated by pulse width modulate (PWM) chip SG3525 into two pulses not overlapped each other. At last the pulses are used to spring IGBT after they are magnified. The PWM switch powers are applied in wire feeding and tractor speed control system. The voltage feedback PI algorithm is used to adjust wire-feed speed, which is controlled with closed-loop. The pulses are respectively produced by PWM chip SG3524 and HSO.O of MCU. In addition, the functions of peripheral circuit are given. The safeguard circuit mainly consists of over-current, over-heat, over-voltage and low-voltage circuits. The system control software is made up of modular subroutines, the function of each subroutine is introduced in detail. According to the control characteristic of much tasks of SAW, some optimization designs are used in software, which have coordinated each controlled procedure rationally.Reliability and noise resistance designs are also covered. In order to reduce their bad infections, some hardware and software measures are adopted The experiment results indicates: The control system has many advantages such as simple circuit, high control precision, strong anti-interference ability, intelligible man-machine dialogue and reliable performance. It can meet the request of power source and process control of SAW and has improved comprehensive performance of the welder and automatic degree.At last, the design of double electrodes SAW and some improved advices are put forward in allusion, which are expected to make the whole system more reliable and more ideal.更多还原