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Ideas for creating a PWM for the cooling fan in a car

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Forseti

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I want to create a PWM for the cooling fan in my car. The fan I have installed is WAY loud and i want to be able to turn it into something more like a 3 speed unit and not waste power by just using resistors. The fan pulls about 30 to 40 Amps and 12 to 14 volts. What PWM design would be he best for this type in installation?
 

Forseti

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fan-pwm

Yes .. it pulls 30 to 40 amps .... its a high power high speed fan that runs 4000+ CFM . that's why I want a PWM so I can reduce it speed when full speed isn't needed because at full speed its very loud.
 

cameo_2007

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pwm fan

okie.
I dont know the answer,you can wait for some experts reply here.

but i am curious about it.So what would be the battery capacity in your car.Doesnt it get drained so quickly. And by the way why is such a high power fan in the car.Is it done normally..? is the fan coming inbuilt straight away from the manufacturer or its your add on..?
I dont know,Just a few doubts doubts.
 

Forseti

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high power pwm fan

The fan is off a 96 Lincoln Mark 8. It is a factory fan. And the PWM off the Lincoln is built into the PCM and Body control unit .... cant be modded for anything outside the original car
 

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pulse width modulation car fan

In principle, it's a buck converter of course. The alternative is in using the motor inductance as energy storage (connecting a fast free-wheeling diode and a PWM switch only) or use an external inductor and possibly a filter capacitor, supplying DC to the motor. I guess, the first variant is used in the manufacturer design, but it should be clarified, that the motor can withstand the involved additional AC current without overheating. Also this "direct chopping" method involves considerable interferences. At best, the motor voltage (waveform and frequency) should be checked in the original design.

Or just try. A PWM frequency of a few to a few ten kHz should work.
 

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