The intelligent fan control circuitTechnical field
The present invention relates to a kind of control circuit of fan, specifically is the control circuit that is used for the fan of communications equipment or communications equipment room.
Background technique
Often will use fan in communications equipment room and the communications equipment dispels the heat, the fan of using in existing communications equipment or the communications equipment room, its control circuit has only simple unlatching and breaking circuit, when control circuit is started working, no matter ambient temperature how much, fan all is free of discontinuities operation in a day 24 hours, and energy consumption is very big.
The model utility content
The purpose of this utility model provides a kind of intelligent fan control circuit, and running or stall that it can control fan according to scene temperature reach purpose of energy saving.
The technical solution of the utility model is such: the control circuit of intelligent fan, comprise the temperature sensing circuit, singlechip control chip, scale operation circuit and the switching circuit that are electrically connected successively, and the output terminal of said switching circuit connects fan.
The used temperature sensor of said temperature testing circuit is temperature sensing chip DS18B20.
The aforementioned proportion arithmetic circuit comprises operational amplifier and peripheral cell thereof, the output terminal that the positive polarity input pin connection reference voltage source of this operational amplifier, negative polarity input pin connect above-mentioned singlechip control chip.
Said switching circuit comprises the triode and the field effect transistor of the output terminal that is connected in the aforementioned proportion arithmetic circuit successively, and fan is connected in the drain electrode of field effect transistor.
After adopting such scheme, the control circuit of intelligent fan of the present utility model, gather current temperature by temperature sensing circuit, read current temperature value by singlechip control chip, convert this temperature value to electrical signal by singlechip control chip and input to the scale operation circuit, the passing ratio arithmetic circuit judges that temperature is higher or lower than setting value, if this temperature is higher than setting value, then switching circuit conducting, the fan entry into service, if this temperature is lower than setting value, then not conducting of switching circuit, fan shuts down.Compared with prior art, whether the running that the utility model can be controlled fan according to scene temperature reaches purpose of energy saving.And this circuit adopts the comparison operation circuit as fan gating work control, because comparison circuit does not have the gating threshold state, the application of threshold state is more stable.
Description of drawings
Fig. 1 is circuit theory diagrams of the present utility model.
Embodiment
The control circuit of intelligent fan of the present utility model as shown in Figure 1, comprises temperature sensing circuit, singlechip control chip, scale operation circuit and switching circuit.
Temperature sensing circuit is mainly by temperature sensing chip T1 (DS18B20, be set at the sampling of 12 megadyne temperature degree, minimum temperature resolution is 0.0625 degree), resistance R 8 and capacitor C 10 constitute, the output terminal of temperature sensing chip T1 is connected to the input end of singlechip control chip IC2;
The scale operation circuit mainly is made of operational amplifier IC1 and peripheral circuit thereof; Resistance R 3 and resistance R 4 are serially connected with between 8V power supply and the ground, and IC1 provides reference potential for operational amplifier; The positive polarity input pin of operational amplifier IC1 is connected on the connection end point of resistance R 3 and resistance R 4; The negative polarity input pin of operational amplifier IC1 is connected in the output terminal of singlechip control chip IC2;
Switching circuit comprises triode Q1 (NPN) and field effect transistor M1, the base stage of triode Q1 is connected in the output terminal of operational amplifier IC1 by resistance R 7, the collector electrode of triode Q1 is connected to the grid of field effect transistor M1, the source electrode of field effect transistor M1 is connected to the 27V power supply, be connected with resistance R 1 between the source electrode of field effect transistor M1 and the grid, the drain electrode of field effect transistor M1 connects fan.
During work, gather current temperature by temperature sensing chip T1, IC2 reads current temperature value by singlechip control chip, convert this temperature value to negative polarity input pin that electrical signal inputs to operational amplifier IC1 by singlechip control chip IC2, when if operational amplifier IC1 negative polarity input pin level is higher than the positive polarity input pin, operational amplifier IC1 exports high level, be carried in the voltage on the triode Q1 base stage, make triode Q1 conducting, the source level of field effect transistor M1 is its conduction value, be on state, it is fan power supply that the electric current that power supply provides is able to by field effect transistor M1, the fan work that brings into operation.Otherwise, when the negative polarity input pin level of operational amplifier IC1 is lower than the positive polarity pin, operational amplifier IC1 output low level, being carried on the triode Q1 base stage is low level, makes triode Q1 be in cut-off state, triode Q1 resistance approach infinity, the source level of field effect transistor M1 is near zero, be in cut-off state, the electric current that power supply provides can't be the fan power supply by field effect transistor M1, and fan quits work.
Singlechip control chip IC2 can set the temperature that will control by upper-position unit, when the temperature that samples as temperature sensing chip T1 is higher than institute's controlling temperature scope, then keep fan running, by fan temperature is controlled, limit control fan, limit feedback sample temperature, limit control temperature, up to temperature stabilization at institute's controlling temperature.
Compared with prior art, whether the running that the utility model can be controlled fan according to scene temperature reaches energy-conservation purpose. And this circuit adopts the comparison operation circuit as fan gating job control, because comparison circuit does not have the gating critical condition, the application of critical condition is more stable.