PWM motor control

Thread Starter

Tobias

Joined May 19, 2008
158
I am wanting to control a 24v motors speed. I am using a PIC 16F886 with a P type MOSFET. Using the CCP1 output to control the MOSFET with HPWM. What is a good frequency to use? Any suggested MOSFET part numbers?

Thanks
 

SgtWookie

Joined Jul 17, 2007
22,230
Why a P-ch MOSFET?

It would be easier to use an N-ch MOSFET; that way you can switch the low side of the load. Besides, N-ch MOSFETs have better specs than their complementary P-ch versions.

If you are wanting to go higher than a few hundred Hz, you're going to need a gate driver IC.

What is the motor's current at stall?
 

SgtWookie

Joined Jul 17, 2007
22,230
If you have the PWM above 25kHz, it will be beyond audio range, so you won't hear it. However, it takes a fairly capable gate driver to turn a MOSFET on and off quickly at those speeds.

At low PWM speeds, you'll have more losses in the motor, and you'll hear the motor "sing". However, you can get by without a gate driver.

I don't see stall current listed. Highest current shown is 7.14A near the bottom. Stall current will be several times that.
 

Thread Starter

Tobias

Joined May 19, 2008
158
Thanks, I will look around for a N-Type MOSFET IC Driver schematic. Any suggestions on MOSFET and drivers?
 
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