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电梯控制方法可编程序控制器(PLC)的优缺点浅析

发布时间:2019-12-31 18:04

  摘要:随着我国的经济发展,PLC的应用正不断的普及,同时带动着传统控制检测的更新,其应用极为广泛。电梯作为现代高层建筑的一种交通工具,与人们的生活密切相关,随着生活水平的提高,也有了电梯运行的安全、效率、舒适性等要求,电梯得到了快速发展,目前常用的方法有两种控制电梯的方法,一它是由传统的继电器控制系统;第二控制方式是使用可编程控制器PLC取代继电器控制系统。比较优势和所设计的控制系统由传统的继电器和PLC控制系统的缺点,体现了PLC的优点在使用S7-200 PLC控制电梯,使用的编程语言来实现电梯的自动运行控制功能,从而大大提高了电梯的可靠性。

  可编程序控制器(PLC)因其结构简单、可靠性高、维护方便等优点,可用于电梯控制。利用PLC S7-200 PLC控制电梯的四层,对四层电梯的PLC控制系统设计直观的描述。详细介绍了PLC控制的四层电梯的设计要求,并列出了输入输出点。

  关键词:可编程控制器;S7-200;PLC;四层电梯

  由继电器组成的顺序控制系统是最早的一种实现电梯控制的方法。但是,进入九十年代,随着科学技术的发展和计算机技术的广泛应用,人们对电梯的安全性、可靠性的要求越来越高,继电器控制的弱点就越来越明显。

  电梯继电器控制系统故障率高,大大降低了电梯的可靠性和安全性,经常造成停梯,给乘用人员带来不便和惊忧。且电梯一旦发生冲顶或蹲底,不但会造成电梯机械部件损坏,还可能出现人身事故。

  可编程序控制器(PLC)最早是根据顺序逻辑控制的需要而发展起来的,是专门为工业环境应用而设计的数字运算操作的电子装置。PLC的最大特点在于:电气工程师已不再电气的硬件上花费太多的心计,只要将按钮开关或感应器的输入点连接到PLC的输入点上就能解决问题,通过输出点连接接触器或继电器来控制大功率的启动设备,而小功率的输出设备直接连接就可以。

  PLC的内部包含了具有中央处理器的CPU,并带有外部I/O口扩展的I/O接口地址和存储器三大块组成,CPU的核心是由一个或者多个累加器组成,它们具有逻辑的数学运算能力,并能读取程序存储器的内容通过计算后去驱动相应的存储器和I/O接口;I/O口将内部累加器和外部的输入和输出系统连接起来,并将相关的数据存入程序存储器或者数据存储器中;存储器可以将I/O口输入的数据存入存储器中,并在工作时调转到累加器和I/O接口上,存储器分程序存储器ROM和数据存储器RAM,ROM可以将数据永久的存入存储器中,而RAM只能作为CPU计算时临时计算使用的缓冲空间。

  PLC的抗干扰是极其优秀的,我们根本不用去关心它的使用寿命和工作场合的恶劣,这些所有的问题已不再成为我们失败的主题,而留给我们的是关心如何来利用PLC的内部资源为我们加强设备的控制能力,使我们的设备更加的柔性。

  PLC的语言并不是我们所想象的汇编语言或C语言来进行编程,而是采用原有的继电器控制的梯形图,使得电气工程师在编写程序时很容易就理解了PLC的语言,而且很多的非电气专业人士也对PLC很快认识并深入。

  鉴于其种种优点,目前电梯的继电器控制方式己逐渐被PLC控制所代替。同时,由于电机交流变频调速技术的发展,电梯的拖动方式己由原来直流调速逐渐过渡到了交流变频调速。因此,PLC控制技术加变频调速技术己成为现代电梯行业的一个热点。

  1.PLC控制电梯的优点:

  (1)在电梯控制中采用了PLC用软件实现对电梯运行的自动控制,可靠性大大大提高。

  (2)去掉了选层器及大部分继电器,控制系统结构简单,外部线路简化。

  (3)PLC 可实现各种复杂的控制系统,方便地增加或改变控制功能。

  (4)可进行故障自动检测与报警显示,提高运行安全性,并便于检修。

  (5)用于群控调配和管理,并提高电梯运行效率。

  (6)更改控制方案时不需改动硬件接线。

  2.电梯变频调速控制的特点:

  随着电力电子技术、微电子技术和计算机控制技术的飞速发展,交流变频调速技术的发展也十分迅速。电动机交流变频调速技术是当今节电、改善工艺流程以提高产品质量和改善环境、推动技术进步的一种主要手段。变频调速以其优异的调速性能和起制动平稳性能、高效率、高功率因数和节电效果,广泛的适用范围及其它许多优点而被国内外公认为最有发展前途的调速方式。

  交流变频调速电梯的特点:

  (1)能源消耗低。

  (2)电路负载低,所需紧急供电装置小。

  在加速阶段,所需起动电流小于2.5 倍的额定电流。且起动电流峰值时间短。由于起动电流大幅度减小,故功耗和供电缆线直径可减小很多。所需的紧急供电装置的尺寸也比较小。

  (3)可靠性高,使用寿命长。

  (4)舒适感好。

  电梯运行是跟随最佳给定的速度曲线运行的。其特性可适应人体感受,并保证运行噪声小,制动平稳。

  (5)平层精度高。

  (6)运行平稳无噪声在轿厢内,机房内及邻近区域确保噪声小。因为其系统中采用了高时钟频率。始终产生一个不失真的正弦波供电电流。电动机不会出现转距脉动。因此,消除了振动和噪声。

  3. 电梯控制技术。

  所谓电梯控制技术是指电梯的传动系统及操纵系统的电气自动控制。作为我国 2 0 世纪 70 年代电梯的主要标志是交流双速电梯。其调速方法是采用改变电梯牵引电动机的极对数,两种或两种不同级对数的绕组,其中极数少的绕组称为高速绕组,极数多的绕组称为低速绕组。高速绕组用于电梯的起动及稳速运行,低速绕组用于制动及电梯的维修。

  80 年代初,VVVF变频变压系统控制的电梯问世。它采用交流电动机驱动,却可以达到直流电动机的水平,目前控制速度已达 6 米/秒。它的体积小,重量轻,效率高,节省能源等几乎包括了以往电梯的所有优点。是目前最新的电梯拖动系统。

  电梯在垂直运行过程中,有起点站也有终点站。对于三层楼以上的建筑物的电梯,起点站和终点站之间还没有停靠站,起点站设在一楼,终点站设在最高楼。设在一楼的起点站称为基站,起点站和终点站称为两端站,两端站之间称为中间站。

  各站厅外设有召唤箱,箱上设置有供乘用人员召唤电梯用的召唤按钮或触钮,一般电梯在两端站的召唤箱上各设置一只按钮或触钮。中间层站的召唤箱各设置两只按钮或触钮。对于无司机控制的电梯,在各层站的召唤箱上均设置一只按钮或触钮。而电梯的轿厢内部设置有(杂物电梯除外)操纵箱。操纵箱上设置有手柄开关或与层站对应的按钮或触钮,操纵箱上的按钮或触钮城内指令按钮或触钮。外指令按钮或触钮发出的电信号称为外指令信号,内指令按钮或触钮发出的电信号成为内指令信号。20世纪80年代中期后,触钮已被微动按钮所取代。作为电梯基站的厅外召唤箱,除设置一只召唤按钮或触钮外,还设置一只钥 匙开关,以便下班关电梯时。司机或管理人员把电梯开到基站后,可以通过专用钥匙扭动该钥匙开关。把电梯的厅门关闭妥当后,自动切断电梯控制电源或动力电源。

  4.PLC 控制电梯的设计。

  随着城市建设的不断发展,高层建筑不断增多,电梯在国民经济和生活中有着广泛的应用。电梯作为高层建筑中垂直运行的交通工具已与人们的日常生活密不可分。实际上电梯是根据外部呼叫信号以及自身控制规律等运行的,而呼叫是随机的,电梯实际上是一个人机交互式的控制系统,单纯用顺序控制或逻辑控制 是不能满足控制要求的,因此,电梯控制系统采用随机逻辑方式控制。目前电梯 的控制普遍采用了两种方式,一是采用微机作为信号控制单元,完成电梯信号的采集、运行状态和功能的设定,实现电梯的自动调度和集选运行功能,拖动控制则由变频器来完成; 第二种控制方式用可编程控制器(PLC)取代微机实现信号集选控制。从控制方式和性能上来说,这两种方法并没有太大的区别。国内厂家大多选择第二种方式,其原因在于生产规模较小,自己设计和制造微机控制装置成本较高;而PLC可靠性高,程序设计方便灵活,抗干扰能力强、运行稳定可靠等特点,所以现在的电梯控制系统广泛采用可编程控制器来实现。

  5.电梯控制系统。

  电梯的控制主要是指对电梯在运行过程中的运行方向、轿内指令、层站召唤、负载信号、楼层显示、安全保护等指令信息进行管理,操纵电梯实行每个控制环节的方式和手段。

  电梯的用途不同,可以有不同的载荷,不同的速度及不同的驱动方式和控制方式。即使相同用途的电梯,也可采用不同的操纵控制方式。但电梯不论使用何种控制方式,所要达到的目标是相同的,即根据轿厢内指令信号、层站召唤信号而自动进行逻辑判定,决定出哪一台电梯接受信号,自动定出电梯的运行方向,并按照指令要求通过电气自动控制系统完成预定的控制目的。

  电梯控制系统分类。

  从控制系统的实现方法来看,电梯的控制系统经历了继电器电梯控制、可编程序控制器(PC机)、单片微机控制、多微机控制多种形式,这些控制方式代表了不同时期电梯控制系统的主流,并且随着大规模集成电路和计算机技术的发展而逐步推陈出新,这些控制系统在目前的在用电梯中都有存在。

  PLC控制系统:PLC是可编程序控制器的简称,它是一种数字运算操作的电子系统。它采用可编程序的存储器存储执行逻辑运算、顺序控制、定时、计数和算术运算等操作指令,并可通过数字式或模拟式输入和输出。

  用PLC控制电梯的方法是,将电梯中发出的指令信号诸如基站的电源钥匙、轿内选层指令、层站召唤、各类安全开关、位置信号等都作为PLC的输入,而将其它的执行元件如接触器、继电器、轿内和层站指示灯、通讯设施等作为PLC的输出部分。

  根据电梯的操纵控制方式,确定程序的编制原则。程序设计可以按照继电器逻辑控制电路的特点来完成,也可以完全脱离继电器控制电路重新按电梯的控制功能进行分段设计。前者程序设计简单,有现成的控制线路作依据,易掌握;后者可以使相同功能的程序集中在一起,程序占用量少。

  PLC用于电梯的控制系统具有可靠性高,稳定性好;编程简单,使用方便;维护检修方便等优点。

  现在PLC产品,品种齐全,已成系列化,输入输出点数从30点一直到8千多点乃至更多。完全可以满足不同层高的电梯控制要求。

  Abstract

  Peng D. The Application of PLC in Elevator Control System[J]. Journal of Nanchang Institute of Aeronautical Technology, 2000.

  With the development of China's economy, PLC applications are constantly popular, while driving the traditional control of the update, its application is extremely extensive. The elevator as a modern high-rise building a means of transport, and people's lives are inseparable, with the improvement of people's living standards, the elevator running safety, efficiency, comfort and other requirements also rose, making the elevator got Rapid development, the current way of controlling the elevator commonly used in two ways, one is composed of traditional relay control system; the second control method is to replace the PLC with programmable logic controller control system. The purpose of this design is to compare the advantages and disadvantages of the control system composed of the traditional relay and the control system of the PLC. The advantages of the PLC are reflected, and the S7-200 PLC is used to control the elevator, and the programming language is used to realize the Elevator automatic operation of the control function, which greatly improve the reliability of the elevator.

  Programmable controller (PLC) because of its simple structure, high reliability and easy maintenance, etc., can be very good for elevator control. Through the use of programmable controller S7-200 PLC control four-story elevator work, intuitive description of the four-story elevator PLC control system design method. Details of the four-story elevator through the PLC design requirements, the specific list of the input and output points, and gives the system ladder design.

  Key words: Programmable control devices;S7-200;PLC;Four-story elevator

  Composed by the order of relay control system is a realization of the first elevator control method. However, to enter the nineties, with the development of science and technology and the widespread application of computer technology, the safety of elevators, reliability of the increasingly high demand on the relay control weaknesses are becoming evident.

  Elevator control system relays the failure rate high, greatly reduces the reliability and safety of elevators, and escalators stopped often to take with the staff about the inconvenience and fear. And the event rather than taking the lift or squat at the end of the lift will not only cause damage to mechanical components, but also personal accident may occur.

  Programmable Logic Controller (PLC) is the first order logic control in accordance with the needs of developed specifically for industrial environment applications to operate the electronic digital computing device. The PLC biggest characteristics lie in: The electrical engineering teacher already no longer electric hardware up too many calculations of cost, as long as order the importation that the button switch or the importation of the sensors order to link the PLC up can solve problem, pass to output to order the conjunction contact machine or control the start equipments of the big power after the electric appliances, but the exportation equipments direct conjunction of the small power can.

  PLC internal containment have the CPU of the CPU, and take to have an I/ O for expand of exterior to connect a people's address and saving machine three big pieces to constitute, CPU core is from an or many is tired to add the machine to constitute, mathematics that they have the logic operation ability, and can read the procedure save the contents of the machine to drive the homologous saving machine and I/ Os to connect after pass the calculation; The I/ O add inner part is tired the input and output system of the machine and exterior link, and deposit the related data into the procedure saving machine or data saving machine; The saving machine can deposit the data that the I/ O input in the saving machine, and in work adjusting to become tired to add the machine and I/ O to connect, saving machine separately saving machine RAM of the procedure saving machine ROM and dates, the ROM can do deposit of the data permanence in the saving machine, but RAM only for the CPU computes the temporary calculation usage of hour of buffer space.

  The PLC anti- interference is very and excellent, our root need not concern its service life and the work situation bad, these all problems have already no longer become the topic that we fail, but stay to our is a concern to come to internal resources of make use of the PLC to strengthen the control ability of the equipments for us, make our equipments more gentle.

  PLC language is not we imagine of edit collected materials the language or language of Cs to carry on weaving the distance, but the trapezoid diagram that the adoption is original after the electric appliances to control, make the electrical engineering teacher while weaving to write the procedure very easy comprehended the PLC language, and a lot of non- electricity professional also very quickly know and go deep into to the PLC.

  Given its advantages, at present, the relay control the lift has been gradually replaced by PLC control. At the same time, AC variable frequency motor speed control technology, the way the lift drag speed has been a gradual transition form DC to AC frequency converter. Thus, PLC control technology increases VVVF Elevator modern technology has become a hot industry.

  1. PLC elevator control advantages:

  (1) Used in elevator control PLC, with so ware for automatic control of lift operation, reliability greatly increased.

  (2) Layer was removed and majority of the relay, the control system structure is simple, simplify the external circuit.

  (3) PLC can be a variety of complex control system, easy to add or change control functions.

  (4) PLC can be automated fault detection and alarm display to improve the operation of security and ease of maintenance.

  (5) For the group control the allocation and management, and improve the efficiency of elevator operation.

  (6)Do not need to change the control scheme changes when the hardware connection.

  2. VVVF elevator control characteristics.

  With the power electronics, microelectronics and computer technology to control the rapid development of technology, communication technology VVVF also a very rapid rate. AC variable frequency motor speed control technology is the power to improve the process in order to improve product quality and improving the environment and promoting technological progress as a primary means. Frequency of its excellent performance and the speed brake from a smooth performance, high efficiency, high power factor and power-saving of a broad scope of application and many other advantages of being at home and abroad recognized as the most promising approach speed.

  Exchange characteristics of VVVF Elevator:

  (1) low energy consumption.

  (2) low load circuit, the re emergency power supply device of small.

  In the acceleration stage, the required start-up current of less than 2.5 times the rated current. Peak starting current and time is short. Since the starting current is drastically reduced, so power consumption and power supply cable diameter can be reduced a lot. Required for emergency power supply devices are also relatively small size.

  (3) high reliability and long service life.

  (4) good comfort.

  Elevator operation is best to follow the speed curve of a given operation. Their characteristics can be adapted to human feelings, and to ensure that noise operation, smooth brake Ping layer and high precision.

  (5) stable noise-free.

  (6) In the car, the engine room and adjacent areas to ensure that noise. Because their systems use a high clock frequency. Always produce a true sine wave power supply current yet. Motor torque ripple does not appear. Therefore, to eliminate vibration and noise.

  3. Elevator control technology.

  The so-called elevator control technology refers to the elevator drive system and electrical control system of automatic control. 70 as the 20th century in China’s elevator were marked by the exchange of two-speed elevator. Its speed is used to change the elevator traction motor of the very few, two or mute-level approach to the number of windings, very few of them as high-speed winding of the winding, a very few number of windings as the low-speed winding. Windings for high-speed elevator-speed start-up and running, low-speed windings for braking and the maintenance of elevators.

  The early 80s, VVVF inverter controlled variable lift system available. It uses AC motor drivers, are able to reach the level of DC motor, control the speed of the current has reached 6 m/sec. Its small size, light weight, high efficiency, energy saving, inc1uding the past almost all the advantages of the lift. Is the latest elevator drive system

  Operation in vertical lift, there is also the starting point of the terminus station. For more than three-story elevator buildings, the starting point of the terminal stations and stops between the had not, the starting point for these stations at the first floor of the terminal located at the highest floor. Starting point in the first floor of the station known as base stations, known as the starting point at both ends of the terminal stations and stations at both ends of intermediate stops between stations.

  Outside the station has a call box, box set are used by staff for elevator call button or touch the call button, the general ends of the lift stations in the call box on the Settings button or touch of a button. 1iddle layer of the station set up the call box button or touch button 2. No drivers for the control of elevators, at various stations are set up calls me on a button or touch button. Elevator car and the internal settings (except for debris elevator) to manipulate me. Control box switch on the handle or set up stations and the corresponding layer of buttons or touch-button control box on the touch-control button or command button or touch the city button. Outside the command button or touch-button issue as the signal outside the command signal, within the command button or touch-button issue within the signal as a command signal. 80 In the mid-20th century, the touch button has been replaced by micro-button.

  As the elevator call box outside the base station, in addition to set up a call button or touch button, but a1so set a key switch in order to work the elevator clearance. Drivers or management staff to open the elevator to the base station can wriggle through a dedicated key to the key switch. Close the elevator in place to autocratically cut off the elevator control power supply or power supply.

  4. PLC Control Elevator Design.

  With the continuous development of urban construction, the increasing high-rise buildings, elevators and life in the national economy has a broad application. Elevator high-rise buildings as a means of transport in the vertical run of daily life have been inextricably linked with people. In fact the lift is based on external call control signals, as well as the laws of their own, such as running, and the cal1 is random, the lift is actually a man-machine interactive control system, simple to use control or logic control order can not meet the control requirement, and therefore, elevator control system uses a random control logic. Elevator control is current1y generally used in two ways, first, the use of computer as a signal control unit, the completion of the lift signal acquisition, operation and function of the se, to achieve the lift and set the autocratic scheduling function to run the election, drag the control from inverter to complete; the second control mode with programmable logic controller (PLC) to replace the computer control signal sets the election. From the control and performance, these two types of methods and there is no significant difference. Most of the domestic manufacturers to choose the second approach, because the smaller scale of production there design and manufacture of high cost of computer control devices; and PLC high reliabi1ity, convenient and flexible program design, anti-interference ability, stable and reliable operation of the characteristics of Therefore, the elevator control system is now widely used to realize programmable control.

  5. Lift control system.

  Lift control system is used to manipulate each control process by managing such commands as running direction, car call, landing call, load signal, landing indication, safety protection.

  Lifts in different applications have different load, speed and drive / control modes. Lifts in same application may also have different control mode. Whatever control mode is adopted, the objective is the same, to be specific, according to car call and landing call, lift control system will execute automatic logic judgment to determine which lift will receive signal, which direction lift will run towards and complete programmed control objective through electrical automatic system based on command.

  Types of lift control system.

  Control system development chronicle indicates that there has appeared many control modes, such as such as relay control, PLC, single computer control, multiple-computer control. Prevailing in different era, these control modes are still employed in lifts now due to massive integrated circuit and computer technology development.

  PLC control system.

  As abbreviation of programmable logic controller, PLC is an electronic system featuring digital computation. It adopts programmable EPROM to execute logic computation, order control, timing, number counting, arithmetic computation, besides, it can input and output through digital or analogy modes.

  The mechanism of PLC control is as follows: input of PLC includes such command signals, as power key to home landing, car call, landing call, various safety switches, position signal, while output of PLC includes contactor, relay, indicators of car / landings and communication unitary, indicators inside car and switch, position signal, are input to PC, while other executing com.

  Programming principle is determined by lift control mode. Programming can either be made according to relay logic control circuit or individually in different phases according to lift control functions after completely separating from relay control circuit. Based on the ready made control circuit, the former is simple and easy to master, while the latter involves less programs by integrating programs of small function.

  Used in lift control system, PLC has such advantages, as high reliability, stability, easy programming, user-friendliness, convenient maintenance & inspection.

  Nowadays, there is a wide range and series of programmable logic controllers. Input / output points range from 30 to 8000 or above, so as to meet lift control requirements with different landing number.


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