Development Of Control System On Frequency Conversion And Energy Saving Of Central Air Conditioning's Water Circulation

The paper is based on a practical application on embedded system which gets computer software's copyright certificate.It is the object of project to control fans and pumps real-timely in water circulation of central air conditioning (for short: WCCAC). Through states and parameters design, it realizes the work of relay and transducer.The hardware of WCCAC frequency conversion and energy saving control system is controlled by the MCU——MC68HC908GP32, which is produced by Freescale company . It contains fan module, led module, RS485 communication module, JB8 parallel port's simulation communication module and power module. In the design of hardware, the paper uses anti-jamming design to ensure a steady signal; uses photoelectric segregation to limit system noise and reduce the interfere from ground; uses filtering and averaging a set of numbers to ensure the veracity of the signals from sensor.The software part includes MCU design and PC design. MCU software design follows the criteria for software programming of embedded system, finishing the design of system initialization, data acquisition, automatically logic control and hardware driver of relay, transducer and communicating. PC design accords to object oriented programming, realizing the design of real time control, device test, AD acquisition's physical quantity correction, date, energy consumption and system configuration modules. Corresponding to these modules, we design interfaces which can display current operating states and is easy to use and maintenance. After the design and test of software and hardware, we have had a field debugging. Comparing with usual operating, our control system can save 32% electric energy which satisfies our custom greatly.There are four main innovations in this subject. First, sufficiently designing the control system according to the principle of software engineering improves maintainability and portability of system. Second, sufficiently using flash on-line programming under user mode realizes the automatically recovery when the electricity goes off and improves the robustness of system. Third, sufficiently considering the dynamic design of PC interface improves the immediacy and vitality of management. Finally sufficiently using user-defined agreement improves the validity and steady of communication.