基于PLC的电梯控制系统文献

Intelligence Building

In 1980s the first intelligence mansion had been completed in America, then intelligence building has been a broadly taken attentions by the whole world. The concept of intelligence building has been put different meanings along with the development of society. The early stage intelligence building had been thought that it is equal to the intelligence mansion, but now the intelligence building not only includes the intelligence mansions but also involves intelligence residential districts. This paper mainly discusses one subsystem of intelligence building system: the elevator control system.

In intelligence residential districts the enterprise’s information managing system mainly takes charge of the things which related to the daily life, for example supervising the district equipments, managing vehicles, disposing critical situations and so on.The elevator supervising and control system is also necessary to the intelligence residential districts. How to make people feel safe, stable and comfortable and how to save energy resources and protect environments and so on are the basic requirements to the elevator control system.

PLC is a common industry control device. It is a special industry control computer which has the perfect function and simple frame. The PLC strong ability in interference and so on makes the elevator industry one after another to apply the PLC to the elevator control system, in order to replace the relay being used in traditional elevator control system. The Application of PLC in the elevator control system reduces the breakdown rate and efficiently improves the operating reliability of the elevator with safety. This paper mainly discusses the elevator control system’s working principles, the system’s software and hardware realization methods and so on.

The Working Principles of Elevator Control System are stated as follows: The spot control information is send into the PLC from the customer input devices firstly, then the PLC control cabinet is required to send out the control signal to drive the equipments according to the system demands. The elevator can then perform the homologous action according to the control request. There are velocity feedback devices in system, which adopt measure velocity generators to provide the elevator velocities and generally are installed in the tail of tow motors. So this is a feedback control system, which can improve the system’s control precision.

It is not necessary to do interface circuit in the elevator’s PLC control system. What we should do is to send the signals to PLC digital input terminals. The signals include inside and outside calling signals, floor location inspecting signals, limiting location signals, opening and shutdown the elevator door signals etc. The DC power which is provided to PLC can be used as indicator light power. The PLC output points can be directly used to control transducers for the purpose of electrical motor’s positive turn and reverse, stop and control each segment velocity and so on.

Moreover, input and output devices are needed in elevator control system, besides the PLC, system’s major control device.

The control cabinet is the control center, from which we can send out various control commands. The control cabinet often was installed in the elevator room. The electric devices and signal systems, for example the contactors, relays, capacitances, resistors, rectifiers and transformers etc, are centralized in the control cabinet. The Power of the control cabinet was

derived from control cabinet was delivered to tow electric motors. Others control lines and signal lines were separately sent to each floor junction.

The design includes two parts: hardware and software. The hardware design is the base of software. Considering that the control demands are relatively complex, we design the programs separately according to the control function. Furthermore, we follow the principle as follows: When the elevator is ascending, the ascending demands are prior to other demands.When the elevator is descending, the descending demands are prior to other demands. The Sequential Function Chart(SFC) is adopted during the boxes to form elevator’s executive circuitry design. It is a method specially used in industrial sequential control. The SFC method can describe the system’s working procedure in great detail.

When all SFC are drawn and I/O address lists are presented, we can convert the SFC to Ladder Diagram(LD). Considering the strict demands for time and for locked each other, we introduce working bits to remember working steps. We should write out the working bits control program, which can link together each step and make the pervious step as the next step restriction condition. Thus the actual outputs are the logic combination of these working steps.

The system program has been debugged completely at present. Simulated experiment enunciates that the design method is viable. Application of PLC in the elevator control system is an effective method. It can make the personnel of the industry management center to long-distance monitor and control the elevator in control center, to connect the elevator system with intelligence building industry management system by Ethernet or special-purpose network such as Lon Works. The elevator, but also can lower the elevator maintenance costs etc. It is one of the developing direction of intelligence building elevator control system.

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 spec …… 此处隐藏：6042字，全部文档内容请下载后查看。喜欢就下载吧 ……