基于PLC電梯控制系統(tǒng)的設(shè)計(jì)-外文翻譯

1、翻譯局部英文原文Design and Practice of an Elevator Control System Based on PLCAbstractThis paper describes the development of 2 nine-storey control system adopts PLC as controller,and uses a parallel connection dispatching rule based onminimum paper gives the basic structure,control principle and realizatio

2、n 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 the reliability and performance of the elevators.With the development of architecture technolog

3、y,the building is taller and tallerand elevators become important vertical transportation vehicles in high-rise buildings.They are responsible to transport passengers, living,working or visiting in the building,comfortable and efficiently to their destinations.So the elevator control system is essen

4、tial 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-critical issue.The traditional electrical control system of elevators is a relay-controlled system.It has the disadvantages such as com

5、plicated circuits,high fault ratio and poor dependability;and greatly affects the elevators running quality.Therefore,entrusted byan enterprise,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

6、is reliable in operation and easy for maintenance.This paper introduces the basic structure,control principle and realization method of the elevator PLC control system in detail.2.System structureThe purpose of the elevator control system is to manage movement of an elevator in response to users req

7、uests.It is mainly composed of 2 parts:2.1.Electric power driving systemThe electric power driving system includes:the elevator 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 c

8、ontacts to substitute the plenty of intermediate relays. The circuits of traction motor are reserved.Thus the original control cabinets disadvantages,such as big volume and high noise are overcome efficiently.2.2.Signal control systemThe elevators control signals are mostly realized by PLC.The input

9、 signals are:operation modes,operation control signals,car-calls,hall-calls,safety/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

10、 judgment of elevator car, choose layer and direction selection of the elevator,etc.The PLC signal control system diagram of elevator is showed in Figure 1.Figure 1 PLC signal control system diagramThe goal of the development of the control system is to control 2 elevators in a 9-storey residential

11、building.For each elevator,there is a sensor located at every floor.We can use these sensors to locate the current position of the elevator car.The elevator ar 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.Th

12、ere is another sensor on the door can detect objects when the door is closing.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

13、 segment LED to display the current location of the 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 elevatorGenerally,an elevator has three operation states: n

14、ormal mode,fire-protection 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 fi

15、re switch acts.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 elevato

16、r has 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 flo

17、or,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 panel or the fl

18、oor 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 onboard passengers traveling in the

19、 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 elevatorsIn this situation,there are two elevators to serve the t runs at 7am to 9am and 5pm

20、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 operation of two elevators will follow a certain dispatching principle.An elevator doesnt stop at a f

21、loor if another car is already stopping,or has been stopped there.The normal operation of elevators is implemented by cooperation of its electric power driving system and logic control system.3.Software designDue to the random nature of call time,call locations and the destination of passengers,the

22、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 Table1 and Table 2.Table

23、 1 Input pointsTable 2 Output pointsAbout software designing,we adopt the modularized information transmission between modules is achieved by intermediate register bit of PLC.The whole program is mainly composed of 10 modules: hall-call registration and display module,car-call registration and displ

24、ay module,the signal combination module,the hall-call cancel module,the elevator-location display module,the 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

25、 typical modules is described as follows:3.1.Hall-call registration and displayThere are two kinds of 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

26、 registration.When a passenger presses a button in the elevator car, the signal will be registered 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

27、the callscontinuous display.Figure 2 up hall-call registration and display collective selection of the calls showed in Figure3,M5.1-M5.7,M6.0 and M6.1 are auxiliary relays in PLC.They denote the stopping request signal of 1st to 9th floor respectively.The auxiliary relay M6 there is a call in a cert

28、ain floor,the stopping 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 callsThe program of this module can make the elevator

29、 response the 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.Figure 3 The combination of the callsFigure 4 The cancellation of up callsIn Fig

30、ure4,the 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.M0.1 to M0.7 denotes the car-calls stopping request signal of f

31、loor 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 is no

32、t served and the registration is remained.The cancellation of down hall-calls is reversed with up hall-calls.3.4.Elevators directionThe elevator may be moving up or down,depending on the combination of hall-cal following ladder diagram in Fig.5 illustrates that the elevator will move up. Figure 5 Up

33、 moving of the elevatorFigure5 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 connectedon.W

34、hen 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 Q3.1 which can ensure the cancellations reliability.3.5.Elevators floor-stoppingFigure6 shows the ladder diagram of the

35、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 system should send

36、 out the floor-stopping signal.4.Minimum waiting time algorithmIn 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 other is the control of a gr

37、oup 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 to move from one floor to another;t

38、o serve as many passengers as possible in a given time1.Figure 6 The elevators floor-stoppingThere 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 traffi

39、c 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 usually has very small average waiting times,but individu

40、al 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 residential buildings is relatively low and even in every floor.

41、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.Considering all of the reasons above,we adopted the “minimum waiting

42、timealgorithm to realize the 2 elevatorsparallel running4.4.1.Evaluation functionThe goal of the“minimum waiting timealgorithm is to predict the each elevators response time according to all calls,and select the elevator which has the shortest response time to serve.When there is a call,the system c

43、alculates out the function values of each elevator according the evaluation function showed in(1)and(2):J(*)=MinJ(1),J(2),J(n) (1)J(i)=Tr(i)+KTd(i)+KTo(i)i=1,2,.,n (2)J(i)is the evaluation index of each elevator;Tr(i) denotes the time of the elevator directly moving to the destination corresponding

44、the latest call from its current floor;To(i)denotes the additional acceleration and deceleration time of a floor-stop of the elevator;Td(i) denotes the average time of the passenger boarding and alighting the elevator;and K is the sum of hall-calls and car-calls.But when a hall-call and a car call c

45、orresponds the same floor,the K is only calculated one time.4.2.Calculation of minimum waiting timeIn equation(2),K is a certain value,To and Td can be obtained by means of statistics.Tr=T*L,where T denotes the average time of the elevator passing by one floor;L denotes the desired floors of the ele

46、vator from current floor to the hall-call floor.In order to calculate the L value,we defined the 2 elevators are A and B respectively;YA,YB denotes the current floor of elevator A and B respectively.H is the corresponding key value when a hall-call button is pressed,and H=floor number of the hall-ca

47、ll.We defined 4 tables for the PLC realization:up hall-call registration table,down hall-call registration table,car-call registration table of A and car-call registration table of B.When a certain call button is pressed,its floor value is recorded in corresponding table.Here we take elevator A as a

48、n example.First,define the variable MA,MB and MW.Where MA,MB denotes the extreme value of car-calls with same direction of A or Bs movement respectively.When elevator A is up-moving,set MA is equal to the maximum value in car-call registration table A;when elevator A is down-moving,set MA is equal t

49、o the minimum value in car-call registration table A.MW denotes the extreme value of hall-calls with same direction of As movement.When elevator A is up-moving and up-hall-call valueYA,set MW=0;otherwise,set MW is equal to the elevator A is down-moving and up-hall-call valueYA,set MW=0;otherwise,set

50、 MW is equal to the maximum value in down-hall-call registration table A.Thus,we can determine the L value according to YA,H, MA and MW.There are 3 situations:(1)When the hall-calls direction is opposite to elevator As movement:L=|YA-MA|+|MA-H|(3)(2)When the hall-calls direction is same as elevator

51、As movement and it is in the front of elevator A:L=|YA-H|(4)(3)When the hall-calls direction is same as the elevator As movement and it is in the back of elevator A:L=|YA-MA|+|MA-MW|+|H-MW|(5)So the i-th floors minimum waiting time can be calculated by(6)as follows:Time(i)=TL(i)+KTd(i)+KTo(i)i=1,2,.

52、,n(6)When the calls change during the operation of elevators,the system calculates the minimum waiting time of each elevator.Then it allocates the current call to the elevator which has small value.When the each elevator has the same value,then the current call is prior to elevator A.When an elevato

53、r is wrong or not in service,the system can exit the dispatching algorithm and turns to a single elevator running mode.4.3.Algorithm realizationCompared with single elevator running mode,the parallel running mode is mainly different at the processing method about hall-calls.The former uses collectiv

54、e selective control method,and the latter uses dispatch rule combined with collective selective control method.Here the system is to control a 9-storey building,so we choose two Siemens S7-200 PLCs(CPU226)and its Extensive Modules to control the single elevator respectively.And by using PPI Protocol

55、 to realize the communication between 2 PLCs.The PPI Protocol adopts master-slave communication mode,so we defined elevator A as the master and elevator B as the slave.By communication program,the 2 PLCs can exchange the massage such as the current position, hall-calls or car-calls and moving direct

56、ion.Then by using“minimum waiting timealgorithm,the system realizes the optimal operation of 2 elevators.Figure7 shows the ladder program of the car-calls extreme value calculation of elevator A.In Figure7,VB121VB130 is the register address of elevator As car-call corresponding to each floor,Q3.1 is

57、 the up-moving lamp of elevator A,and the car-calls extreme value is saved in VB120. Figure 7 The car-calls extreme value calculation of elevator AIn 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 operated for 1 year,and its operation scenarios are as follows:(1)DownPeakThis traffic condition concerns people out of the building in the morning between 7am to 9am.(2)UpPeakThis condition concerns people entering the building between 5pm to 7pm.(3)OtherIt covers the day fr