汽车学院毕业设计科技文献翻译汽车学院毕业设计科技文献翻译Applied to the electrical system programmable logic controller PLC应用于电气系统的可编程序控制器应用于电气系统的可编程序控制器姓姓 名名 专专 业业 电气工程及其自动化电气工程及其自动化 学学 号号 班班 级级 四四 班班 指导教师指导教师 2013 年 4 月 1Applied to the electrical system programmable logic controller PLCThis article mainly introduces the electrical system, research methods are effective and simple to state sequence programming controller provides a control pneumatic actuator motion and gas apparatus dynamic system. The project of a specific controller for pneumatic applications join the study of automation design and the control processing of pneumatic systems with the electronic design based on microcontrollers to implement the resources of the controller.1. IntroductionThe automation systems that use electro-pneumatic technology are formed mainly by three kinds of elements: actuators or motors, sensors or buttons and control elements like valves. Nowadays, most of the control elements used to execute the logic of the system were substituted by the Programmable Logic Controller (PLC). Sensors and switches are plugged as inputs and the direct control valves for the actuators are plugged as outputs. An internal program executes all the logic necessary to the sequence of the movements, simulates other components like counter, timer and control the status of the system.With the use of the PLC, the project wins agility, because it is possible to create and simulate the system as many times as needed. Therefore, time can be saved, risk of mistakes reduced and complexity can be increased using the same elements.A conventional PLC, that is possible to find on the market from many companies, offers many resources to control not only pneumatic systems, but all kinds of system that uses electrical components. The PLC can be very versatile and robust to be applied in many kinds of application in the industry or even security system and automation of buildings.Because of those characteristics, in some applications the PLC offers to much resources that are not even used to control the system, electro-pneumatic system is one of this kind of application. The use of PLC, especially for small size systems, can be very expensive for the automation project.An alternative in this case is to create a specific controller that can offer the exactly size and resources that the project needs 3, 4. This can be made using microcontrollers as the base of this controller.The controller, based on microcontroller, can be very specific and adapted to only one kind of machine or it can work as a generic controller that can be programmed as a usual PLC and work with logic that can be changed. All these 2characteristics depend on what is needed and how much experience the designer has with developing an electronic circuit and firmware for microcontroller. But the main advantage of design the controller with the microcontroller is that the designer has the total knowledge of his controller, which makes it possible to control the size of the controller, change the complexity and the application of it. It means that the project gets more independence from other companies, but at the same time the responsibility of the control of the system stays at the designer hands2. Electro-pneumatic systemOn automation system one can find three basic components mentioned before, plus a logic circuit that controls the system. An adequate technique is needed to project the logic circuit and integrate all the necessary components to execute the sequence of movements properly.For a simple direct sequence of movement an intuitive method can be used 1, 5, but for indirect or more complex sequences the intuition can generate a very complicated circuit and signal mistakes. It is necessary to use another method that can save time of the project, make a clean circuit, can eliminate occasional signal overlapping and redundant circuits. The presented method is called step-by-step or algorithmic 1, 5, it is valid for pneumatic and electro-pneumatic systems and it was used as a base in this work.The method consists of designing the systems based on standard circuits made for each change on the state of the actuators, these changes are called steps. 3The first part is to design those kinds of standard circuits for each step, the next task is to link the standard circuits and the last part is to connect the control elements that receive signals from sensors, switches and the previous movements, and give the air or electricity to the supply lines of each step. In Figs. 1 and 2 the standard circuits are drawn for pneumatic and electro-pneumatic system 8. It is possible to see the relations with the previous and the next steps. 3. The method applied inside the controller The result of the method presented before is a sequence of movements of the act