Unit FourteenControl and Building Automation SystemWhat is an intelligent building?Schematic Diagram of an Intelligent Building SystemUp to now, there has not been a universally accepted definition for an Intelligent Building.Most existing definitions of IB around the world centre on the need for a building to be suitable for the occupants to work and live in safely, comfortably, effectively and efficiently.“Intelligent building is something that make stupid people feel not as stupid as they are”.Intelligent Building can bring usReduced Resource ConsumptionBoth home and building technology offer tremendous potential savings through intelligent controls.Optimized Convenience and More ComfortApart from minimizing consumption costs, private home owners will be interested in higher levels of convenience, safety and security.Smart Home is an integration of various systems at home such as security, home automation, lighting control, CCTV and entertainment system which is coordinated by a smart home controller and controlled by users using various centralized command interfaces such as a touch screens, keypads, universal remote controllers, internet browser, telephone, and even your LCD TV screen.Smart Home SystemsCCTV: Closed Circuit TelevisionCCTV: China Central TelevisionOn/off ControlThe control device can be positioned only to a maximum or minimum state (e.g., on or off). Because On/off control is simple and inexpensive, it is used extensively for both industrial and commercial control. A typical home thermostat that starts and stops a furnace is an example of On/off action.Floating ControlDead (neutral) zone盲区 停滞区In floating control, the controller can perform only two operations moving the controlled device toward either its open or closed position, usually at a constant rate. Generally, a neutral zone between the two positions allows the controlled device to stop at any position when the controlled variable is within the differential of the controller. When the controlled variable falls outside the differential of the controller, the controller moves the controlled device in the proper direction.openshutTimeUpper limitLower limitneutral zoneTemperatureValveset pointcontrolled variableproportional band outputoffsetProportional control requires a continuously variable output of the controlled device. The control system produces an output which is proportional to the error signal, i.e. the difference between the value of the controlled variable and the set point.Proportional control signalresponseIntegral controlDerivative control signalresponseProportional plus Integral (PI) ControlProportional-Integral-Derivative (PID) ControlProportional Action.Closed loop controlFeedbackA closed loop or feedback control measures actual changes in the controlled variable and actuates the controlled device to bring about a change. The corrective action continues until the variable is brought to a desired value within the design limitations of the controller. This arrangement of having the controller sense the value of the controlled variable is known as feedback.Example of Feedback ControlRoom Air Temperature ControlOpen loop controlAn open loop control does not have a direct link between the value of the controlled variable and the controller. An open loop control anticipates the effect of an external variable on the system and adjusts the set point to avoid excessive offset. An example is an outdoor thermostat arranged to control heat to a building in proportion to the calculated load caused by changes in outdoor temperature. In essence, the designer presumes a fixed relationship between outside air temperature and the heat requirement of the building and specifies control action based on the outdoor air temperature. The actual space temperature has no effect on this controller. Because there is no feedback on the controlled variable (space temperature), the control is an open loop.Single-Seated Valves Double-Seated Valves单座阀 双座阀Three-Way Mixing Valves Three-Way Diverting Valves三路混合阀 三路换向阀SensorsTemperature Sensors Humidity SensorsPressure Transmitters and TransducersFlow Rate Sensors Indoor Air Quality SensorsLighting Level SensorsControllersPneumatic Receiver-ControllersElectric/Electronic ControllersDigital ControllersThermostats1. Control ModesOn/Off control Proportional control Floating control Integral control Derivative controlVariation and Combination of basic modes 2. Open and closed loop control open loop control closed loop control3. Building Automation Systems3.1 General3.2 Basic Considerations3.3 Computer Based Systems Frequently used words and phrases:control mode 控制模式 On/Off Control 开/关控制 Proportional control 比例控制 Floating control