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Time-proportional control: more from an on/off switch
http://asu.in.ua/viewtopic.php?f=25&t=465
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Автор:  san [ 26 серпня 2014, 00:24 ]
Тема повідомлення:  Time-proportional control: more from an on/off switch

Time-proportional control: more from an on/off switch
http://e-ditionsbyfry.com/Olive/ODE/CTL ... w=document
Цитата:
Time-proportional control, a form of pulsewidth modulation, is a mathematical technique that allows a feedback controller to use an on/off or discrete actuator as if it were a continuous actuator capable of generating control efforts anywhere between 0% and 100%. The trick is to turn the actuator on and off for periods proportional to the desired control effort.
Consider a home cooling system, for example. Most thermostats use a “bang-bang” control algorithm that compares the actual room temperature with the setpoint specified by the room’s occupants, then turns the air conditioner fully on or fully off if the temperature is more than a few degrees too high or too low. This technique causes the room temperature to fluctuate around the setpoint, but in most homes, that’s good enough.
The thermostat could achieve tighter control with a continuous actuator such as a motorized damper that would continuously allow a measured amount of chilled air into the room. Those are common in commercial HVAC applications but are typically too expensive for home use.

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