基于PLC的电动挖掘机变频调速系统设计毕业设计论文_精品.doc

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 学 号 学生姓名 指导教师 完成日期 2013年 6 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 states key projects have been started, the demand of electric excavator will rise rapidly. As the heart 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 interfa