| Air-condition is a typical heat exchange system. Its construction and process of heat exchange are very complex. Compared with air-conditions in buildings,the bus air-conditions work in the bad conditions and we have much more difficulties in the control of them. First,the heat load of bus air conditions always changes and it is difficult to define the controlling parameters. Second,the drop of temperature in railway carriage must be quickly. Finally,we can not use electric power but the engine of bus or subsidiary engine to drive air compressors of bus air conditions. Because the change range of turnaround speed of engine is very wide,that brings difficulties in controlling the rate of flow of cold-producing medium.In the control of bus air-conditions,preventing evaporator from freezing to make the air-conditions work with high efficiency and controlling the temperature of railway carriage are the basic tasks in air-condition control. In our country,most buses still use CCTXV system and CCOT system to control air-conditions. These ways have not a higher accuracy in control. They will short down the working life of air compressor because they are always started or stopped when we want to make the railway carriage stay in a fixed temperature. Now,automatic and intelligent control systems are being applying in bus air-conditions control. In this way,computers control the work of air compressor,the turnaround speed of fan,the open degrees of wind controlled doors and so on. This controlling way can make the passengers feel much comfortable and make the bus air-conditions work with a high efficiency.In this thesis,a single-chip microcomputer fuzzy controlling system with MCU:AT89C51 is designed to deal with the bus whole air-condition composed with refrigerating system and heating system. Via controlling the open of temperature door,turnaround speed of evaporator fan and subsidiary engine,it can control temperature of railway carriage. Via starting and stopping air compressor,it can make the ice of evaporator melt. This controlling system can display the temperature of railway carriage,control temperature with multi-grade setting and modify controlling parameters on line.The algorithm of fuzzy controller is revising factor (a)consulted on line fuzzy control with integral link. The input of controlling system are temperature deviation(E) and deviation changing rate(EC). The output of system(u) is occupying parameter of adjusting pulse. All of them are transformed into fuzzy number. In fact,the control of revising factor consulted on line is composed by two fuzzy controller. One is double input and single output fuzzy system with controlling construction of IF E AND EC THEN a . The other is the double input and single output fuzzy system with controlling construction of IF E AND EC THEN occupying parameter of adjusting pulse. The fuzzy algorithm can be summered with such formula:The fuzzy controller with revising factor is a adapting fuzzy controller. It realize self-adjusting of controlling rules on line. To improve the controlling quality of this system,it permit user modify controlling parameters. User can input integral coefficient - Kt. Scaling coefficient can be adjusted by controlling system accordingto E and adjusting scale inputted by user. In the thesis,the stability of this double input and single output fuzzy system is analysed with language model and simulate this kinds of fuzzy controller. The result displays this fuzzy controller has better controlling quality than PID or other controlling ways.The circuit is composed by four parts. First is interface circuit between person and machine. It obtains 8155,LED display,simply keyboard. Second is store circuitcomposed by single-chip microcomputer-AT89C51 and EEPROM -AT93C66. The third is sample circuit composed by three digital temperature sensor-DS1820. The final is output circuit. AT93C66 is three wires micro-wire serial bus EEPROM. It is used to store setting parameters and working state,such as temperature of railway carriage,scaling... |
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