The HVAC Controller Base On Embedded System With Intelligent Control

Embedded System is the new developing direction of the technology in IT field after Network technology. With the outstanding features of small size, strong performance, low power consumption, high reliability, and domain-oriented applications, Embedded System is widely used in the various fields of national defense, consumer electronics, information appliances, network communications, industrial control, etc.The paper discusses the traditional PID control and its parameters tuning by analyzing the characteristics and problems of the HVAC PLC control system, in order to find the solution to the problems that the PID control parameters tuning is very laborious, time-consuming, difficult to achieve networking, can't use Internet remote control. The paper also propose to use the embedded intelligent controller of the HVAC based on fuzzy PID control system to meet the non-linear, large inertia, time-varying parameters of the HVAC control system. What's more, this can implement HVAC control parameters setting in an easy, fast and stable way, also can meet the standards of the hardware and software interfaces for the maturing Internet remote Web control.On the basis of the study of Samsung S3C2440A embedded chips bases on ARM920T core, the paper designs input and output, AD conversion, DA conversion interface circuits for the specific application. The paper also analyses the traditional PID control algorithm, and then we can achieves a fuzzy PID controller with chilled water of the HVAC system based on it. As for software design, we use open-source linux operating system to achieve cutting, compiling and transplanting of it, then compiling and transplanting of the related drivers of the target board. Ultimately, we realize the application system interface design using the Qtopia and Qt/E embedded graphics environment, the program of fuzzy PID, AD and DA conversion using C++ programming environment, cross-compiling in the linux embedded environment to achieve the hardware and software design of the HVAC controller based on embedded system with intelligent control.The operational tests show that the embedded HVAC controller has friendly interface, and the application of fuzzy PID can solve the problems with parameter tuning. So it is entirely possible to replace the company's current PLC control system with it.