石家庄铁道大学毕业设计
基于PLC的电动挖掘机变频调速控制
系统设计
Design of the Variable Frequency Control System
of the Electric Excavator Based on PLC
2013 届 机械工程 学院 专 业 测控技术与仪器
完成日期 2013年 6 月11 日
摘要
电动挖掘机价格低，耗能少，无污染，在矿山、交通、建筑尤其是城建市政现场施工中应用广泛。随着国家各项重点工程的的相继开工，电动挖掘机的需求量将迅速增涨。变频调速系统作为挖掘机的“心脏”，直接影响挖掘机的工作效率，所以研究电动挖掘机的变频调速系统对节能和环保具有重要意义。
论文分析了传统发动机作为动力的调速系统，设计了用电动机和变频器替代传统发动机作动力的调速控制系统总体方案。进行了系统建模和PID参数整定。由PLC输出控制信号到变频器，变频器将电动机转速调整到相应的数值，转速传感器反馈转速信号给PLC，构成闭环控制系统。利用GX Developer软件设计了：手动调速、自动调速、自动怠速、PID调节、AD、DA、看门狗等模块。用Protel软件设计了PLC和变频器的相关接口电路、电源电路、转速测量电路、抗干扰电路。进行了PLC、AD和DA模块、变频器、电动机、转速传感器的选型。使用MCGS组态软件设计了人机交互界面，操作和维护方便。
在实验室搭建了控制系统平台，对部分硬软件进行了调试，效果良好，达到了设计要求。
关键词：电动挖掘机、步进电机、变频器、PLC、组态软件。
Abstract
Electric excavators have many advantages：Low cost, low power consumption and less pollution. It is widely used in mining, transportation, construction, especially in urban construction. With the state's key projects have been started, the demand of electric excavator will rise rapidly. As the \of the excavator, Frequency control system directly affects the efficiency of the excavator, so it is important for energy-saving and environmental protection to study the frequency control system of electric excavator.
In this paper we analyzed the traditional control system in which engine is the power, an overall program is designed that motor and converter replace traditional engine-powered speed control system. Systematic modeling and PID parameter tuning are conducted. PLC output control signals to the inverter, the inverter will adjust the motor’s speed to an appropriate value, the speed sensor feedbacks speed signal to the PLC, a closed loop control system is formed. We designed a few blocks with the GX Developer programming software: Manual control, automatic control, automatic idle speed, PID regulation, AD, DA, watchdog modules. With Protel software we designed the PLC and inverter relevant interface circuit, power circuit, speed measuring circuit, anti-jamming circuit. A selection of PLC, AD and DA modules, inverter, motor, speed sensor is conducted. A Human Machine Interface is designed with MCGS configuration software, operation and maintenance are easy.
A control system platform is built in the laboratory, a debugging is carried out on part of hardware and software, design requirements are achieve with good effect.
Key words: electric excavator、stepper motor、inverter、PLC、configuration software.
目录
第1章 绪论 ......................................................................................................................... 1
1.1 课题来源以及重要意义 ......................................................................................... 1 1.2 国内外研究现状 ..................................................................................................... 1
1.2.1 国内发展及现状 ........................................................................................... 1 1.2.2 国外发展及现状 ........................................................................................... 2 1.3 关键技术与技术难点 ............................................................................................. 3 第2章 主要技术指标和主要功能 ..................................................................................... 5
2.1 技术指标 ................................................................................................................. 5 2.2 主要功能 ................................................................................................................. 5 2.3 预期达到的成果及其形式 ..................................................................................... 6 第3章 总体设计方案 ......................................................................................................... 7
3.1 设计思想 ................................................................................................................. 7 3.2 技术路线 ................................................................................................................. 7 3.3 设计原理 ................................................................................................................. 7 第4章 控制系统数学模型建立和PID参数整定 ............................................................. 1
4.1 控制系统数学模型建立 ......................................................................................... 1
4.1.1 输出电压与转速差的转换模型 ................................................................... 1 4.1.2 变频器模型建立 ........................................................................................... 1 4.1.3 电动机模型建立 ........................................................................................... 2 4.1.4 系统传递函数 ............................................................................................... 2 4.2 PID 参数整定 .......................................................................................................... 3 第5章 硬件设计 ................................................................................................................. 5
5.1 电路设计 ................................................................................................................. 5
5.1.1 变频器和PLC的相关接口电路 .................................................................. 5 5.1.2 变量泵转速检测电路 ................................................................................... 6 5.1.3 供电电路设计 ............................................................................................... 7 5.1.4 抗干扰设计 ................................................................................................... 8 5.1.5 触摸屏设计 ................................................................................................... 8 5.2 硬件选型 ................................................................................................................. 9
5.2.1 PLC选型 ........................................................................................................ 9 5.2.2 电动机的选型 ............................................................................................. 11 5.2.3 变频器的选型 ............................................................................................. 11 5.2.4 AD/ DA模块选型 ........................................................................................ 12 5.2.5 转速传感器的选型 ..................................................................................... 13
第6章 软件设计 ............................................................................................................... 17
6.1 软件设计语言和准备工作 ................................................................................... 17 6.2 程序模块 ............................................................................................................... 18
6.2.1 转速控制 ..................................................................................................... 18
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