1、PDF外文：http:/ 3765 字 附录 英文原文 2008 Workshop on Power Electronics and intelligent Transportation System Design and Practice of an Elevator Control System Based on PLC Xiaoling Yang1,2,Qunxiong Zhu1,Hong Xu1 &
2、nbsp; 1 College of information Science &Technology, BeijingUniversity of Chemical Technology, Beijing 100029, China 2 Automation College of BeijingUnionUniversity,Beijing,100101, China &
3、nbsp; yxl_lmy , , Abstract This paper describes the development of 2 nine-storey elevators control system for a residential building. The control system adopts PLC as controller, and uses a parallel connection dispatching rule based on "minimum waiting time" to run 2 elev
4、ators in parallel mode. The paper gives the basic structure, control principle and realization method of the PLC control system in detail. it also presents the ladder diagram of the key aspects of the system. The system has simple peripheral circuit and the operation result showed that it enhanced t
5、he reliability and performance of the elevators. 1. 1ntroduction With the development of architecture technology, the building is taller and taller and elevators become important vertical transportation vehicles in high-rise buildings. They are responsible to transport passengers, living
6、, working or visiting in the building, comfortable and efficiently to their destinations. So the elevator control system is essential in the smooth and safe operation of each elevator. it tells the elevator in what order to stop at floors, when to open or close the door and if there is a safety-crit
7、ical issue. The traditional electrical control system of elevators is a relay-controlled system. it has the disadvantages such as complicated circuits, high fault ratio and poor dependability； and greatly affects the elevators running quality. Therefore, entrusted by an enterprise, we have improved
8、electrical control system of a relay-controlled elevator in a residential building by using PLC. The result showed that the reformed system is reliable in operation and easy for maintenance. This paper introduces the basic structure, control principle and realization method of the elevator PLC
9、 control system in detail. 2. System structure The purpose of the elevator control system is to manage movement of an elevator in response to users requests. it is mainly composed of 2 parts: 2.1. Electric power driving system The electric power driving system includes: the e
10、levator car, the traction motor, door motor, brake mechanism and relevant switch circuits. Here we adopted a new type of LC series AC contactors to replace the old ones, and used PLCs contacts to substitute the plenty of intermediate relays. The circuits of traction motor are reserved. T
11、hus the original control cabinets disadvantages, such as big volume and high noise are overcome efficiently. 2.2. Signal control system The elevators control signals are mostly realized by PLC. The input signals are: operation modes, operation control signals, car-calls, hall-calls, safe
12、ty/protect signals, door open/close signal and leveling signal, etc. All control functions of the elevator system are realized by PLC program, such as registration, display and elimination of hall-calls or car-calls, position judgment of elevator car, choose layer and direction selection of the elev
13、ator, etc. The PLC signal control system diagram of elevator is showed in Figure 1. 2.3. Requirements The goal of the development of the control system is to control 2 elevators in a 9-storey residential building. For each elevator, there is a sensor located at every floor. We can use t
14、hese sensors to locate the current position of the elevator car. The elevator car door can be opened and closed by a door motor. There are 2 sensors on the door that can inform the control system about the doors position. There is another sensor on the door can detect objects when the door is closin
15、g. The elevator cars up or down movement is controlled by a traction motor. Every floor, except the first and the top floor, has a pair of direction lamps indicating that the elevator is moving up or down. Every floor, has a seven segment LED to display the current location of the
16、 elevator car. The first step for the development of the elevator control is to define the basic requirements. informally, the elevators behavior is defined as follows. (1) Running with a single elevator Generally, an elevator has three operation states: normal mode, fire-protectio
17、n mode and maintenance mode. The maintenance mode has the highest priority. Only the maintenance mode is canceled can the other operation modes be implemented. The next is fire-protection mode, the elevator must return to the bottom floor or base station immediately when the fire switch acts.
18、The elevator should turn to normal operation mode when the fire switch is reset. Under normal operation mode, the control systems basic task is to command each elevator to move up or down, to stop or start and to open and close the door. But is has some constraints as follows: Each elevator ha
19、s a set of 9 buttons on the car control panel, one for each floor. These buttons illuminate when they are pressed and cause the elevator to visit the corresponding floor. The illumination is canceled when the corresponding floor is visited by the elevator. Each floor, except the first and the top fl
20、oor, has two buttons on the floor control panel, one to request an up- elevator, one to request a down-elevator. These buttons illuminate when they are pressed. The illumination is canceled when an elevator visits the floor, then moves in the desired direction. The buttons on the car control p
21、anel or the floor control panel are used to control the elevators motion. The elevator cannot pass a floor if a passenger wants to get off there. The elevator cannot stop at a floor unless someone wants to get off there. The elevator cannot change direction until it has served all onboar
22、d passengers traveling in the current direction, and a hall call cannot be served by a car going in the reverse direction. if an elevator has no requests, it remains at its current floor with its doors closed. (2) Parallel running with two elevators in this situation, there
23、are two elevators to serve the building simultaneously. it runs at 7am to 9am and 5pm to 7pm every day. When an elevator reaches a level, it will test if the stop is required or not. it will stop at this level when the stop is required. At the same time, to balance the number of stops, the op
24、eration of two elevators will follow a certain dispatching principle. An elevator doesnt stop at a floor if another car is already stopping cooperation of its electric power driving system and logic control system. 3. Software design Due to the random nature of call time, call locations
25、 and the destination of passengers, the elevator control system is a typical real-time, random logic control system. Here we adopted collective selective control method with siemens PLC S7-200 CPU226 and its extension modules. There are 46 input points and 46 output points in the system. The i/O points are showed in Tablei and Table 2. About software designing, we adopt the modularized method to write ladder diagram programs. The information transmission between modules is achieved by intermediate register bit of PLC.
