Design And Simulation Of Automatic Air Conditioner For Passenger Car Based On Fuzzy Control

With the improvement of people's standards of living and the rapid development of auto industry, modern high technology and electrical technology, the people who have higher and higher standard and requirement for the riding comfort and controlling of the passenger car hope that various temperatures can be controlled at the same time to meet the different need of passengers in the car's different place, so the air conditioner need to be controlled in multiple temperature zones. At present, only advanced cars'air conditioner is computer-controlled, the ordinary ones even installed not fully functioning manual or electronically controlled air conditionering which has a number of shortcomings in the function and use. As a result, to satisfy the need of comfort and safety, it is hoped that the function of car air-conditioning devices to further improve and at the same time reduce costs and energy consumption so as to make car air-conditioning control system to achieve automation and intelligent.The features,working principles and two forms of gas distribution of car air-condition are described in detail. The two forms include full thermal type and hybrid intrusion. The first type has high precision of controlling temperature in-car at the cost of cooling capacity;The second can save cooling capacity, but its disadvantage is that warm-and cold wind can not be well mixed , so the controlling precision is lower relatively. Though combining the advantages of two forms, the passenger car automatic air conditioner's duct is preliminary designed in this paper, so that it can distribute different air flow to multiple temperature zones, improve passenger's comfort and save energy consume. According to the climate characteristics and conditions, the comfort parameters are introduced and analysis in paper as well.Fuzzy Control which is one a controlling way that can simulate human thought, language and behavior in use of fuzzy mathematics method in the process of controlling is suitable with the condition that it is difficult to set up exact mathematical model or obtain its structure parameters.It use fuzzy control rules which is based on people's experience in the control process to realize control, as a result, it can adapt to the strongly change of control parameter; apply to not only simple control but also complex nonlinear control. This method is suitable for car air-conditioning because it is a nonlinear time-varying system which appropriate temperature is difficult to clearly expressed.In paper, the error and error rate between required temperature and actual value are designed as input; in-car temperature is regulated based on fuzzy control strategy. The paper designs some controllers of car. Left and right blending damper fuzzy controller, wind speed of air-blower fuzzy controller of passenger car are designed; input and output value are fuzzed, relative control strategies are made and output curve surface of the fuzzy controller are designed in paper.According to the law of thermodynamics, the thermodynamic factors which affect temperature in-car are analyzed, a simplified car interior temperature mathematical model of the left and right-zone is established, and thermodynamic simulation model of car air-conditioning is established in Matlab/Simulink software environment. Based on different inputs, the controlling of wind speed of air-blower, open degree of left and right blending damper, the simulation system which is divided into three departments such as fuzzy controller, implementation module of left temperature zone and right temperature zone can respectively simulate and calculate the left and right two-zone temperature and make them to achieve requirements stably and rapidly. System is simulated about summer environment. The result curve proves that the compartment temperature can approach the established temperature quickly. It is turned out that the system realized the controlling of passenger car's multiple temperature zones and the fuzzy controller of automatic air conditioner for passenger car is rationally. Finally, the hardware scheme of passenger car air-conditioning's fuzzy controller is proposed in this paper, and the hardware circuit of control system with Motorola's HCS12 family of 16-bit microcontrollers MC9S12DP256 for core which is designed contains basic peripheral circuits such as power circuit, clock circuit and reset circuit, driver circuit of the left and right blending damper and air-blower, man-machine-channel module, for example, monitors, keyboards and their driver circuits. At first, controlling parameters needed are collected through a variety of temperature sensors and after A / D converted. Secondly, microprocessor does some decision-making based on requirement temperature of the left and right temperature zone and the data detected. Finally, the temperature of passenger car multiple temperature zones can be regulated by controlling the control device such as left and right blending damper and air-blower of passenger car automatic air conditioner so as to achieve the target temperature. There is components selection in detail, analysis and design for each module in the paper.