发布时间 : 星期六 文章PLC控制电梯外文翻译 - 图文更新完毕开始阅读
IV. SOFTWARE PROCESS
A. Main Program
Control system proposed from this paper was a system of collective selective control. The modular programming methods were used to classify various properties of output signal, medium registers were used to connect different modules to transmit information. System software could be divided into some follow modules, that is, floor detection circuit module, seven segment LED display floor circuit module, elevator direction selection circuit module, deceleration point signal generator circuit modules, on/off door of elevator car lateral circuit module, button memory lights display circuit module and the other modules. In the floor detection circuit module, floor encoding were read into and memory signals were saved in the corresponding registers until the floor
changes. LED display was controlled in the seven segment display circuit module. Elevator up or down judgments in response to call the elevator were completed in the elevator direction selection circuit module. Main program flow chart of system software was shown in figure 5. B. Floor Display Program
Elevator will running in the deceleration state when current floor consistent with target detection floor. During the process of operation, elevator will go through many floor detection points. Deceleration notification will be emitted only when elevator reach the detect point of goal floor. After receive deceleration notification signal, elevator had started slow down. The flow chart of floor display program was shown in figure 6.
PLC output ports were directly connected with seven- segment LED, which need not external hardware decoder. Seven-segment LED was compiled by PLC software to directly display floor number. The seven-segment LED digital tube was commonly used, which is a digital distribution in a plane by a number of light-emitting diodes or liquid crystal segments to form a variety of digital code. Seven-segment LED digital tube was distributed in a plane. Digital codes of floor were composed by some light-emitting diodes or liquid crystal segments. Seven segment LED display circuit was shown as figure 7.
In the display circuit of seven-segment code, input pin a, b, c, d, e, f, g of LED were connected with 24V power supply, then the corresponding section will be lighted, the control terminals Y10 -Y16 of programmable logic controller will be closed or open, which could control on or off state to appear the corresponding value in the appropriate section of LED. Digital display of values and correspond pins were shown in table I. Among them, output state I was defined as bright field of the seven segments LED; output state 0 was defined as dark field of the seven segments LED.
V. CONCLUDES
Variable frequency speed-regulation and programmable logic controller technology were used to transform old elevator. The reliability of the elevator was improved through reasonable equipment selection, parameter setting and software design. The elevators after transformation have obvious advantages such as structure compact, low noise, high efficiency, simply
maintenance and low failure rate. The elevator based on variable frequency speed- regulation and programmable logic controller technology have improve passenger comfort and reliable.
Maintenance costs and power consumption of motor were reduced significantly. But there are still many areas for improvement: (I) Changed with fluctuate in traffic; the functions of select direction of elevator were optimized to achieve the purpose of efficient transport of passengers. (2)
Emergency approaches will be increased in the fault conditions. These problems will to be perfect in the future.
ACKNOWLEDGMENT
First and foremost, I would like to show my deepest gratitude to my supervisor, Dr. Zhang. a respectable, responsible and resourceful scholar, who has provided me with valuable guidance in every stage of the writing of this thesis. I shall extend my thanks to Mr. Wang for all his kindness and help. I would also like to thank all my teachers who have helped me to develop the
fundamental and essential academic competence. My sincere appreciation also goes to all my friends for their encouragement and support.
采用 PLC 技术的电梯变频调速系统
摘要：本文提出了基于 PLC 测定的变频调速调节系统。首先，对控制系统的整体结构 进行了测定。选择变频器和可编程逻辑控制器，来完成变频调速调节。其次，设定变 频器的系统硬件参数。选择 PLC 的驱动点和 I/O 端子的分配，旋转编码器与 PLC 的接 口连接。最后，在软件设计的基础上，完成软件流程图和梯形图程序，分析出电梯设 计系统的方法。
关键词：变频调速；可编程逻辑控制器；电梯控制系统。
一、引 言
在早期的中国，人的力量被用来作为简单的起重设备，直到现在，北方地区的一些农村手动提取井水的升降装置仍在使用。因此，中国是世界上最早的在电梯的原型[1]方面有建树的国家之一。1854 年，来自美国的格雷夫斯在纽约水晶宫世博会上向世界展示了他的发明，这是史上第一部安全电梯[2]。此后，电梯在世界上得到了广泛的应用。
在现代生活和经济活动中，电梯已经成为了城市的标志。电梯作为重要的垂直运输工具，尤其是在高层建筑中。继电器控制系统曾被用于常规的电梯中，其控制功能和信号处理由硬件来实现。许多的电气元件来共同控制电器[3]。在过去的几年，电梯的生产技术愈发成熟，已形成系列产品。随着经济社会的快速发展和生活质量的提高，由传统的 DC 转换器和继电器控制的电梯，缺点越来越明显，暴露出诸多问题：（1）传统的电梯控制系统故障率较高，主要是由于多次接触，复杂的布线电路。此外，电接点易燃，这可能会导致接触不良。（2）电机控制器与硬件接线根据常用的方式，难以实现更复杂的控制功能，也就是难以提高系统控制的性能。（3）电磁机构和接触点动作慢，机械和电磁惯性大。因此，系统的控制精度难以提高。（4）传统的电梯控制系统也存在一些缺点，如结构庞大，能耗高，机械噪声大等。（5）由于线路复杂、故障率高，必然导致控制系统维护量大、成本高。结果表明，我们应该来完成传统的电梯控制系统的完全改造。
二、变频器参数设定
电梯作为垂直运输的工具，属于位能负载设备，并需要频繁启动和停止[4]。电梯随着载客量，向上、向下变化，电机的最小负荷而变化。当电梯在无负载或重负载下，电机在发电状态。同样地，电机具有最大负载时，在重负载上行或无负载下行状态时，电机处于用电状态。因此，电动机的运行轴[5]的四个象限中。传统的电梯由牵引电动机驱动，电机的工作状态的变化，由接触器实现。在定子电路的串联电阻或串联电抗，且电动机的速度控制由双速异步电动机来完成，不能满足乘客的舒适性。用 PLC 来取代传统继电器控制模式，它可以在电机拖动过程中，从直流调速的模式逐步过渡到交流变频调速。 A.变频器的选择
变频器可以实现电压频率的转换，它可以转换交流与固定频率，交流电压频率调节后供给电机使用。考虑从电梯的控制要求和可靠性，本次设计使用安川 VS-616G5数字变频器。在速度控制系统的电梯中 PG 卡和旋转编码器必须配备于 VS-616G5 变频器，以供给电动机速度控制和反馈动作[7]。通过电机同轴连接的旋转编码器来检测电机的转速。A，B 分别表示为两相旋转编码器的脉冲输出。当 A 相脉冲超前 B 相脉冲 90 度时，电动机正向旋转的状态。类似的，当 A 相脉冲滞后 B 相脉冲 90 度时，电动机操作的反向旋转状态。根据 A，B 脉冲的相序，确定电机的旋转方向。测量电机转速的同时也可以测量出 A，B 脉冲频率或周期。反馈信号发送到 VS-61605 通过 PG卡到变频器[8]。图一所示的脉冲波形 A，B。
B.变频器容量的计算和制动电阻
我们定义电梯曳引机的电机功率为 P1，运行的电梯速度为 V1，起重量为 W1，W2，额外的重量 W3，重力加速度为 G，电源逆变器是 P.随着的最大负载在电梯上升[9]的过程中，牵引功率为 P2。
其中，F1 为摩擦力，
δ 可忽略不计。变频器的功率 P
接近电梯电源 P1，安全性能，必须考虑牵引功率 P2。 P=1.5P2，因此，我们可以得知经验值，
此时，变频器的容量约为 15KW。
随着电梯潜在的能量的加载，可变的频率速度调控系统应该有一个制动函数，因为电梯可能在操作过程中产生可再生的能量。当系统速度控制中使用了 VS-616G5，必须配置制动电阻器。当电梯被用在减速过程时，所述电动从发电状态，反馈到变频器的发电状态。DC 从 AC-DC-AC 逆变器可以增加,当同步速度下降时。制动电阻器的作用是反馈信号抑制直流电压。可再生能源的被消耗了在制动电阻上，通过所述制动单元的制动模式，该模式具有较低的成本和良好的结果。
能源消耗制动电阻器 R2，制动的电流 I z 的值不超过该的变频器电流的二分之一。其中，U0 被定义为变频器额定电压，R2 大于 30 欧姆。因为制动电阻不是长期工作的，电源可能小于所消耗的功率。