北京航空航天大学毕业设计(论文)第I页基于plc的中央空调自动控制系统设计摘要中央空调系统是现代大型建筑物不可缺少的配套设施之一，电能的消耗非常大，约占建筑物总电能消耗的50%。通常中央空调系统中冷冻主机的负荷能随季节气温变化自动调节负载，而与冷冻主机相匹配的冷冻泵、冷却泵却不能自动调节负载，几乎长期在100%负载下运行，造成了能量的极大浪费，也恶化了中央空调的运行环境和运行质量。本文首先介绍了中央空调的结构和工作原理，然后采用西门子的S7—200PLC作为主控制单元，利用传统PID控制算法，通过西门子MM440变频器控制水泵运转速度，保证系统根据实际负荷的情况调整流量，实现恒温控制，同时又可以节约大量能源。关键词：PLC；中央空调；控制I北京航空航天大学毕业设计(论文)第II页DesignofautomaticcontrolsystemforcentralairconditioningsystembasedonPLCAbstractThecentralairconditioningsystemisoneofthenecessarysupportingfacilitiesofmodernlarge-scalebuildings.Theconsumptionofelectricenergyisverylarge,whichaccountsforabout50%ofthetotalenergyconsumption.Thefrozenhostusuallyinthecentralair-conditioningsystemloadcanautomaticallyaccordingtothechangeoftemperatureandloadregulation,refrigerationpumpandcoolingpumpmatchedwiththefrozenhostcanautomaticallyadjusttheload,almostrun100%underloadoperation,resultinginagreatwasteofenergy,butalsoworsentheoperationenvironmentandoperationqualityofCentralairconditioning.Thispaperfirstintroducesthestructureandworkingprincipleofcentralairconditioning,thenuseSIEMENSS7200PLCasthemaincontrolunit,usingthetraditionalPIDcontrolalgorithm,throughtheSIEMENSMM440invertercontrolpumpspeedensuresystemaccordingtotheactualsituationtoadjustloadflow,realizeconstanttemperaturecontrol,butalsocansavealotofenergy.Keywords：PLC;centralairconditioning;controlII北京航空航天大学毕业设计(论文)第III页目录摘要................................................................................................................................I1绪论.............................................................................................................................11.1课题的研究背景..............................................................................................11.2国内外中央空调控制系统的研究现状..........................................................22中央空调控制的原理.................................................................................................42.1中央空调系统的结构和原理..........................................................................42.2中央空调电机的软启动原理及应用..............................................................43中央空调控制系统的硬件设计.................................................................................63.1变频器的原理..................................................................................................63.2西门子MM440变频器性能介绍...................................................................63.2.1主要特征...............................................................................................73.2.2控制性能的特点...................................................................................73.3PLC选型...........................................................................................................73.4人机界面设计..................................................................................................83.5系统硬件设计................................................................................
