With the continuous development of society, China’s urbanization process has also been developing rapidly. With the increasing height of buildings, elevators have become an indispensable means of transportation in the market economy. At present, China’s elevator manufacturing enterprises ignore the elevator’s independent development and development process, and use the main funds to introduce advanced technology from abroad.
This phenomenon will lead to the abnormal development trend of China’s elevator manufacturing enterprises.
Programmable logic controller (PLC) is widely used in elevator industry in China. In this paper, the application of PLC in elevator control system is studied and discussed from the following aspects. An elevator mainly consists of a computer room, a ladder gate, a well way, a car, a station and other systems. The system mainly includes power supply, speed limiter, switch, tractor, signal cabinet, guide wheel, control cabinet, brake brake device, power supply wiring board and machine base. The system mainly includes call box, floor station switch door, hall door, floor display and door lock.
The well system mainly consists of guide rail, buffer, distributor box, track bracket, compensation chain, lighting, speed limiter, counterweight, bottom pit and accompanying cable. The system mainly includes car, layer device, guide shoe, finger lamp, car door, door control box, safety window, alarm device and communication device. The ladder door system is composed of layer door, linkage mechanism, car door, door opener, door lock and other devices. The door opener is the power of connecting layer door and car door, and car door is composed of door boots, door fan, door knife and door guide rail bracket. At present, there are many ways to classify elevator in our country, but there are three kinds of classifications: speed, usage and control.
According to the speed, the elevator is divided into three types of elevators: high speed, medium speed and low speed. According to the usage, elevator can be divided into cargo ladder, passenger ladder, passenger and freight ladder, residential ladder, ship ladder, hospital bed ladder, sundry ladder and sightseeing ladder.
According to the control mode, elevators can be divided into buttons, signals, manual, interstorey, parallel, centralized and group control. The operation cycle of an elevator refers to the time consumed by the elevator running one week or round trip, that is, the time that the elevator starts from the base station and completes the transportation task to return to the base station again. It is worth noting that the time taken for the load to leave the elevator car is also included. The elevator is an automated system without drivers. When the elevator enters the elevator itself, the elevator will close the elevator door after a few seconds of hesitation, and then start to accelerate until it runs smoothly. In the process of operation, the control system also records the call of external floors.
Once the signal is consistent with the direction of operation, the elevator will automatically stop and open the ladder door.
When the operation is completed, the control system will automatically eliminate the signal. When all the same signals are completed, if the external hall does not have a signal to call, the elevator will be on standby, and when the reverse signal appears, the elevator will automatically change and re run. The ideal running curve of the elevator is made to satisfy the comfort of the elevator passengers. The research shows that once the acceleration exceeds one point five meters per second, the passenger will have a strange feeling. At present, China’s elevator usually uses three ideal curves, such as trapezoidal, triangular and sinusoidal waveform, but the trapezoidal curve is the most widely used because of the difficult acceleration of sinusoidal curve acceleration and the excessive acceleration of triangular curve. The essence of programmable controller is an operable digital operation system for industry. Its internal storage device can realize information storage, logical operation, timing, sequence control and other processes. It has strong applicability and anti-interference in the process of operation, so it can be used in industrial production instead of other systems. The most commonly used language for a programmable controller is ladder diagram, and the symbols of ladder diagram are very similar to the schematic diagram of relay used before.
This will greatly shorten the time for technicians to understand and familiar with trapezoidal symbols, and ladder diagram is more intuitive and operational than other curves. The programmable controller has many kinds of hardware devices because of its modular form, which enables users to choose their own configuration when using the system, and different choices will result in different systems. This is also the reason why the programmable controller replaces other relay control systems. Programmable logic controller contains thousands of programming elements, and the existence of these components is the key to achieve complex control process. In addition, when a system with strong logic and insufficient number of components is encountered, the operator can solve the problem by adding extension units. Therefore, the programming system has stronger operational performance than other systems. Programmable controller is a system specially designed for industrial production.
Therefore, it has a large number of anti-interference facilities. Isolation, shielding, battery reserve, power protection and other measures can make the system run without fault in tens of thousands of hours. Therefore, it can be directly applied to industrial production and widely recognized by enterprises. The elevator control system is mainly composed of frequency conversion speed regulating unit, conveying unit and main control unit. The main task of the system is to realize the operation of the elevator door and the traction electrical operation.
In addition, this process also completes the coordinated control of speed, current and displacement through the use of the frequency converter. At present, China’s elevator manufacturing industry will use professional programming software to complete the design of the elevator control system, and the process often uses the function module design method to design. This method first modularized the control function of the elevator system, and then designed the ladder diagram according to the specific functions of each module. By using this method, a unified combination of elevator functions can be realized, so that the whole program structure is clearer and easier to debug, and other functions can be added at any time. In this paper, the application of PLC in elevator control system is discussed in detail from elevator, PLC, control system hardware and software design. As far as China’s current situation is concerned, the development of elevator industry is not consistent with the level of urban development, and the lag of elevator production technology is the key to the occurrence of this phenomenon. Therefore, in the course of future industrial development, funds should be invested in the process of research and development of new technologies, thermostatic element rather than the purchase of high-level elevators to other countries.