I have a 12V motor that I am trying to drive with a PWM signal from a PIC, and I've successfully gotten the circuit to work with an NTE 2986 N-Channel MOSFET. I just have a few questions that came up while I was doing the research on figuring out how to do this (this is my first PWM motor project).
How do we determine the proper frequency of the PWM? I first had the PWM set at 2KHz which did not drive the motor very well, made the MOSFET get hot, and the motor whined at low RPMs. After doing some reading, I hear that most DC motors should be run at 20KHz with PWM, which I set and now the motor seems to work just fine, no whining, and the MOSFET doesn't get hot.
The other question is, what determines the value of the capacitor (bypass capacitor?) that you run in this circuit? I haven't actually put one in yet, but I'm reading values somewhere around 1000uF and rated for twice the voltage that the motor runs at.
Last question, how does putting the diode in parallel with the motor help with anything?
I apologize if any of these questions seem stupid
How do we determine the proper frequency of the PWM? I first had the PWM set at 2KHz which did not drive the motor very well, made the MOSFET get hot, and the motor whined at low RPMs. After doing some reading, I hear that most DC motors should be run at 20KHz with PWM, which I set and now the motor seems to work just fine, no whining, and the MOSFET doesn't get hot.
The other question is, what determines the value of the capacitor (bypass capacitor?) that you run in this circuit? I haven't actually put one in yet, but I'm reading values somewhere around 1000uF and rated for twice the voltage that the motor runs at.
Last question, how does putting the diode in parallel with the motor help with anything?
I apologize if any of these questions seem stupid