基于PLC电梯控制系统的设计与实践毕业论文外文翻译.doc

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1、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 1 College of information Science &Technology, Beijing University of Chemical Technology, Beijing 100029, China 2 Automa

2、tion College of Beijing Union University,Beijing,100101, China yxl_lmy , zhuqx, 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 mi

3、nimum waiting time to run 2 elevators 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

4、result showed that it enhanced the 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 transpor

5、t passengers, living, 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 th

6、ere is a safety-critical 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

7、, we have improved 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

8、 elevator PLC 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 elevator car

9、, 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. Thus the original contro

10、l 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, safety/protect signals, door open/close

11、 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 elevator, etc. The PLC signal control s

12、ystem 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 these sensors to locate the current position of t

13、he 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 closing. The elevator cars up or down movement is cont

14、rolled 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 elevator car. The first step for the development of the elevator c

15、ontrol 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-protection mode and maintenance mode. The maintenance mode has the highest priority. Only the

16、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. The elevator should turn to normal operation mode when the fire switch is reset. Under norm

17、al 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 has a set of 9 buttons on the car control panel, one for each floor. These buttons illuminate when

18、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 floor, has two buttons on the floor control panel, one to request an up- elevator, one to request a

19、 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 panel or the floor control panel are used to control the elevators motion. The elevator cannot pass a fl

20、oor 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 onboard passengers traveling in the current direction, and a hall call cannot be served by a car going in the reverse dir

21、ection. 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 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

22、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 operation of two elevators will follow a certain dispatching principle. An elevator doesnt stop at a floor if another car is already stopping cooperat

23、ion of its electric power driving system and logic control system. 3. Software design Due to the random nature of call time, call locations and the destination of passengers, the elevator control system is a typical real-time, random logic control system. Here we adopted collective selective control

24、 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 be

25、tween modules is achieved by intermediate register bit of PLC.The whole program is mainly composed of i0 modules: hall-call registration and display module, car-call registration and display module, the signal combination module, the hall-call cancel module, the elevator-location display module, the

26、floor selection module, the moving direction control module, the door open/close module, the maintenance operation module and the dispatching module under parallel running mode. The design of the typical modules is described as follows: 3.1. Hall-call registration and display There are two kinds of

27、calls in an elevator: hall-call and car-call. When someone presses a button on the floor control panel, the signal will be registered and the corresponding lamp will illuminate. This is called hall-call registration. When a passenger presses a button in the elevator car, the signal will be registere

28、d and with the corresponding lamp illuminated. This is called car-call registration. Figure2 shows the ladder diagram of up hall-calls registration and display. The self-lock principle is used to guarantee the calls continuous display.3.2. The collective selection of the calls Here the collective se

29、lection control rules are used. As showed in Figure3, M5.i-M5.7, M6.0 and M6.i are auxiliary relays in PLC. They denote the stopping request signal of ist to 9th floor respectively. The auxiliary relay M6.2 denotes the elevator drivers operation signal. When there is a call in a certain floor, the s

30、topping signal of corresponding floor will output. When the elevator is operated by the driver,the hall-calls will not be served. And the elevator cannot pass a floor at which a passenger wishes to alight. 3.3. The cancellation of the calls The program of this module can make the elevator response t

31、he hall-calls which have the same direction as the cars current direction, and when a hall-call is served,its registration will be canceled. The ladder diagram of up hall-callscancellation is showed in Figure4. Figure3 The combination of the calls Figure4 The canclellation of up calls in Figure4, th

32、e auxiliary relay M4.0 is the up moving flag of the elevator. When the current direction of the elevator is up, M4.0s contacts are closed; on the contrary, when the current direction of the elevator is down, M4.0s contacts are opened. M0.i to M0.7 denotes the car-calls stopping request signal of flo

33、or 2 to floor 8 respectively. This program has two functions: (1) Make the elevator response the normal down hall-calls when it is moving down, and when a down hall-call is served, its registration is canceled. (2) When the elevator is moving up, the corresponding floors down hall-call it passing by

34、 is not served and the registration is remained. The cancellation of down hall-calls is reversed with up hall-calls. 3.4. Elevators direction The elevator may be moving up or down, depending on the combination of hall-calls and car-calls. The following ladder diagram in Fig.5 illustrates that the el

35、evator will move up. Figure5 shows that when the calls corresponding floor is higher than the elevators current location, the elevator will go up. Here the auxiliary relay M4.0 is used as the up-moving flag. When the elevator is moving up, the up-moving lamp is illuminated, so the M4.0 is connected

36、on. When the elevator arrives the top floor, the up-moving lamp is off and the timer starts. After 0.2s, the M4.0 is disconnected, the up-moving display is off. Here we used M4.0 to replace Q3.i which can ensure the cancellations reliability. 3.5. Elevators floor-stopping Figure6 shows the ladder di

37、agram of the elevators floor-stopping function. As showed in Figure6, M6.4 is the flag of floor-stopping signal. M6.6 is the floor-stopping signal sent by the driver. M7.0 is the fire signal sent by the fire switch. And M6.7 is the forced speed changing signal. When either of these contacts act, the

38、 system should send out the floor-stopping signal. 3.6. Minimum waiting time algorithm in traffic of elevator systems, there are two types of control task usually. The one is the basic control function to command each elevator to move up or down, to stop or start and to open and close the door. The

39、other is the control of a group of elevators. The main requirements of a group control system in serving both, car and hall calls, should be: to provide even service to every floor in a building; to minimize the time spent by passengers waiting for service; to minimize the time spent by passengers t

40、o move from one floor to another; to serve as many passengers as possible in a given timei. There are many dispatching algorithms for elevators group control. Such as Nearest-neighbor Algorithm2,which the elevator always serve the closet request next; Zoning Algorithm3 which by analyzing the traffic

41、 of elevator system with unequal floor and population demand to dispatch the elevator; and Odd-even rule, which an elevator only serves the odd floor and the other only serves the even floor. The Nearest-neighbor Algorithm minimizes the length of the elevators empty move to the next request. it usua

42、lly has very small average waiting times, but individual waiting times can become quite large2. The Zoning Algorithm usually used in buildings which has heavy traffic situations, such as the office building at lunch time. Compared to the office building and shopping mall, the traffic flow of residen

43、tial buildings is relatively low and even in every floor. Secondly, people usually think of elevators as purely functional objects and the experience of riding an elevator is time waited for most of them.Furthermore, there exist immense problems when attempting to satisfy all requirements.Considerin

44、g all of the reasons above, we adopted the “minimum waiting time” algorithm to realize the 2 elevators parallel running4. 5. Conclusions In this paper, we have improved an old elevator control system by using PLC, and realized the group control of 2 elevators. The new control system has been operate

45、d for 1 year, and its operation scenarios are as follows: (1) DownPeak This traffic condition concerns people out of the building in the morning between 7am to 9am. (2) UpPeak This condition concerns people entering the building between 5pm to 7pm. (3) Other It covers the day from 6:00 to 0:00 excep

46、t the two situations above. And in this situation, there is only one elevator running. The results are expressed via an average waiting time and maximum waiting time(both given in seconds) are collected in Tables 3 and 4. Due to the nonparallel running before the reform, so the average waiting time

47、and maximum waiting time of downpeak and the uppeak are very longer than the reformed. The practice results have showed the better performance of the improved control system. References 1 Ricardo Gudwin, Fernando Gomide, Marcio (i998). “A Fuzzy Elevator Group Controller With Linear Context Adaptatio

48、n”. IEEE World Congress on Computational intelligence . Vol. 12, No. 5, pp.481-486. 2 Philipp Friese, Jorg Rambau (2006). “Online-optimization of multi-elevator transport systems with reoptimization algorithms based on set-partitioning models”. Discrete Applied Mathematics .No. 154, pp.1908-1931. 3 Zheng Yanjun, Zhang Huiqiao, Ye Qingtai, Zhu Changming. (2001). “The Research on Elevator Dynamic Zoning Algorithm and its Genetic Evolution”. Computer Engineering and Applications, No. 22, pp.58