Study On Monitoring System For HVAC Thermostat Controller Based On ZigBee

Energy-saving is a basic requirement of sustainable economic development. As theenergy consumption of building central air-condition system accounts for a large proportionof the community, it has a great significance to achieve its energy-saving technology. Sincethe energy consumption of end devices is the main portion of the total energy consumption ofHVAC system, achieving network cluster control and intelligent management of HVAC is theimportant development direction to its energy saving. Aimed at saving the problem, the paperdesigned a remote monitoring system for HVAC based on ZigBee, after having a deeplyexperimental evaluation to ZigBee network performance. This system included the keytechnologies of network structure, node hardware design, embedded operating system,application development and monitoring platform.Firstly, on the basic of the system’s general requirements analysis, the paper designedthe framework of HVAC system, which included three layers structures about field-controllayer, network transmission layer and central monitoring layer. The field-control layerconsisted of thermostats, fan coil units and electric valve, and the network transmission layerconsisted of router and gateway. The central monitoring layer included central control stationand remote client.Secondly, the data traffic of HVAC system was analyzed. In considering the factors ofnetwork size, data payload size and background load, the experiments about ZigBee typicalnetwork performance were carried out, including transmission distance, network delay, pathcapacity, packet loss rate and network self-healing ability. The result provided a basic dataand reference for building a highly efficient and reliable large-scale ZigBee wireless network.Thirdly, the paper designed the schematic of thermostat, router and gateway. Thethermostat used the STM32F103RET6as the main MCU, and used the CC2530F256as RFmodule. The router used CC2591as front-end power amplifier module. uc/OS II real-timeoperating system and ucGUI were used to achieve embedded GUI control interface for thethermostat.Finally, the paper discussed the architecture and implementation of HVAC system,developed the central monitoring software, which could achieve temperature control, operation management, centralized monitoring, node management, energy consumptionmeasurement and report form output. Proposed time-slot data transmission mechanism andevent-triggered strategy can effectively reduce network traffic and data collision rate. Usingadaptive network register method was to achieve the node intelligent management, whileusing network state table method to achieve network fault monitoring can effectively reduceZigBee network bandwidth.