responsible for the development of company management, including the development of settlement and settlement standards of preparation, the business unit clearing work inspection and guidance, business settlement audit; 23, is in charge of the company business and costs calculation and nalysis of new projects and to develop standards and provide the basis for decision-making and responsible for the comprehensive economic and technical indicators and statistics, analysis, summary and reporting; 24, the company responsible for audits of various types of business contracts, the principal of contract price (purchase price, freight, taxes, etc), payment method, payment, settlement, such as the reasonableness of the data, authenticity, accuracy; 25, strict enforcement of national tax policy, is responsible for the monthly reporting, including tax calculations, statistics, go through the relevant formalities, receive invoices; 26, the company responsible for all kinds of price (including product price, material prices,Freight, engineering machinery jobs price, price, price) 's terms of market surveys, quotations, price exception report; 27, is responsible for the company's management, including conference organized by price, of historical prices, totals, etc; 28, according to the annual operating plan, annual costs and undergo decomposition, control, analysis and evaluation; responsible for costing and cost control, ensure accounting number is reasonable, correct, and complete accounting report and the company's other reports compiled and reported to work;
1 任务分析
1.1分析控制对象
三相步进电动机是一种将电脉冲信号转换成直线位移或角位移的执行元件。步进电机的输出位移量与输入脉冲个数成正比,其转速与单位时间内输入的脉冲数(脉冲频率)成正比,其转向与脉冲分配到步进电机的各相绕组的相序有关。所以只要控制指令脉冲的数量、频率及电机绕组通电相序,便可控制步进电机的输出位移量、速度和转向。步进电机具有较好的控制性能,其启动、停车、反转及其它任何运行方式改变,都在少数脉冲内完成,且可获得较高的控制精度,因而得到了广泛的应用。
1.2三相步进电机的控制要求 三相的控制要求如下:
1能对三相步进电动机的转速进行控制; ○
2可实现对三相步进电动机的正反转控制; ○
3能对三相步进电动机的步数进行控制; ○
攀枝花学院本科毕业设计(论文) 方案设计
2 方案设计
在步进电动机控制系统中,步进电动机作为一种控制用的特种电机,利用其没有积累误差的特点,广泛应用于各种控制中,其控制主要有开环、半闭环、闭环控制。
方案一:开环控制系统
指令脉冲 环形分配器 功率驱动器 步进电动机负 载输 出图2.1 开环步进电动机控制系统框图
开环控制系统没有使用位置、速度检测装置及反馈装置,因此具有结构简单、使用方便、可靠性高、制造成本低等优点。另外,步进电动机受控于脉冲量,它比直流电机或交流电机组成的开环精度高,适用于精度要求不太高的机电一体化伺服传动系统。
方案二:半闭环控制系统
指令脉冲位置比较电路速度控制电路 步进电动机负 载输 出速度反馈 速度传感器 速度传感器位置反馈
图2.2 半闭环步进电动机控制系统框图
半闭环控制系统调试比较方便,并且具有很好的稳定性,不过精度不太高,较少使用。
方案三:闭环控制系统
1
responsible for the development of company management, including the development of settlement and settlement standards of preparation, the business unit clearing work inspection and guidance, business settlement audit; 23, is in charge of the company business and costs calculation and nalysis of new projects and to develop standards and provide the basis for decision-making and responsible for the comprehensive economic and technical indicators and statistics, analysis, summary and reporting; 24, the company responsible for audits of various types of business contracts, the principal of contract price (purchase price, freight, taxes, etc), payment method, payment, settlement, such as the reasonableness of the data, authenticity, accuracy; 25, strict enforcement of national tax policy, is responsible for the monthly reporting, including tax calculations, statistics, go through the relevant formalities, receive invoices; 26, the company responsible for all kinds of price (including product price, material prices,Freight, engineering machinery jobs price, price, price) 's terms of market surveys, quotations, price exception report; 27, is responsible for the company's management, including conference organized by price, of historical prices, totals, etc; 28, according to the annual operating plan, annual costs and undergo decomposition, control, analysis and evaluation; responsible for costing and cost control, ensure accounting number is reasonable, correct, and complete accounting report and the company's other reports compiled and reported to work;指令脉冲位置比较电路速度控制电路 步进电动机负 载输 出速度反馈 速度传感器位置反馈图2.3 闭环步进电动机控制系统框图
闭环控制系统定位精度高,但调试和维修都较困难,系统复杂,成本高。 综合三种方案,根据步进电动机的特点,从制造成本与系统结构复杂程度考虑,本设计采用方案一,在开环控制系统中,用PLC控制三相步进电动机。
攀枝花学院本科毕业设计(论文) 步进电动机的选择
3 步进电动机的选择
现在比较常用的步进电机包括反应式步进电动机,永磁性步进电动机,混合式步进电动机和单相式步进电动机。
永磁式步进电动机一般为两相,转矩和体积较小,步进角一般为7.5度或15度;
反应式步进电动机一般为三相,可实现大转矩输出,步进角一般为1.5度,但噪声和振动都很大。反应式步进电动机的转子磁路由软磁材料制成,定子上有多相励磁绕组,利用磁导的变化产生转矩。
混合式步进电动机是指混合了永磁式和反应式的特点。它又分为两相和五相:两相步进角一般为1.8度,而五相步进角一般为0.72度,这种步进电动机的应用也较为广泛。
由于本设计用PLC控制三相步进电动机,故选用36BF02型反应式步进电动作为控制对象,三相步进电动的步距角为0.750/ 1.50。 此电机有如下特点:
1.反应式步进电机的精度为步进角的3-5%,且不累积。 2.反应式步进电机外表允许的最高温度在摄氏80-90度。 3.反应式步进电机的力矩会随转速的升高而下降
4.反应式步进电机低速时可以正常运转,但若高于一定速度就无法启动,并伴有啸叫声。
此外,步进电机有一个技术参数:空载启动频率,即步进电机在空载情况下能够正常启动的脉冲频率,如果脉冲频率高于该值,电机不能正常启动,可能发生丢步或堵转。在有负载的情况下,启动频率应更低。如果要使电机达到高速转动,脉冲频率应该有加速过程,即启动频率较低,然后按一定加速度升到所希望的高频(电机转速从低速升到高速)。
3
responsible for the development of company management, including the development of settlement and settlement standards of preparation, the business unit clearing work inspection and guidance, business settlement audit; 23, is in charge of the company business and costs calculation and nalysis of new projects and to develop standards and provide the basis for decision-making and responsible for the comprehensive economic and technical indicators and statistics, analysis, summary and reporting; 24, the company responsible for audits of various types of business contracts, the principal of contract price (purchase price, freight, taxes, etc), payment method, payment, settlement, such as the reasonableness of the data, authenticity, accuracy; 25, strict enforcement of national tax policy, is responsible for the monthly reporting, including tax calculations, statistics, go through the relevant formalities, receive invoices; 26, the company responsible for all kinds of price (including product price, material prices,Freight, engineering machinery jobs price, price, price) 's terms of market surveys, quotations, price exception report; 27, is responsible for the company's management, including conference organized by price, of historical prices, totals, etc; 28, according to the annual operating plan, annual costs and undergo decomposition, control, analysis and evaluation; responsible for costing and cost control, ensure accounting number is reasonable, correct, and complete accounting report and the company's other reports compiled and reported to work;
4 三相反应式步进电机工作原理
三相反应式电动机工作原理:
反应式步进电动机转子均匀分布着很多小齿,定子齿有三个励磁绕组,其几何轴线依次分别与转子错开0,?,2?(相邻两个转子齿轴线间的距离为齿距,以
33?表示),即A与齿1相对齐,B与齿2向右错开?,C与齿3向右错开2?,A'(A'与
33A是同一电极)与齿5相对齐,图3-1所示是反应式步进电机定转子的展开图。 ' 图3-1 反应式步进电机定转子展开图
如果A相通电,B、C相不通电时,由于磁场作用,齿1与A对齐,转子不受任何力;如果B相通电,A、C相不通电,则齿2应与B对齐,此时转子向右
移动?,齿3与C偏移?,齿4与A偏移2?;如果C相通电,A、B相不通
333电,则齿3应与C对齐,此时转子又向右移过?,齿4与A'偏移?;继续进
33'行下去,A相通电,B、C相不通电,则齿4与A对齐,转子又向移过?。
3这样经过A,B,C,A分别通电状态,齿4移到A相,电机转子向右转过一个齿距。如果不断地按A,B,C,A,……通电,电机就每步?,向右旋转。按
3A,C,B,A,……通电,电机就反转。
由此可见,电机的位置和速度由通电次数(脉冲数)和频率决定,而方向由通电顺序决定。
不过,出于对力矩、平稳、噪声及减小角度等方面考虑。往往采用A-AB-B-BC-C-CA-A这种通电状态,这样将原来每步?改变为?。因此本设计
36采用PLC控制三相六拍步进电动机,来实现电机的速度、正反转、以及步数的控制。
PLC控制三相步进电动机
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