Re: DC Motor at low speed
What PWM does, is to reduce the average voltage applied to the motor. As a result the torque-speed characteristic goes down. When you connect the motor to a load, that require a certain torque (actually it has it’s own torque-speed characteristic) the equilibrium point will be at a lower speed.
But you could simply reduce the applied voltage instead of PWM!
PWM has it’s advantages, depends what you have available and how complicated you want to make this thing.
You should give more details though:
What motor is it: permanent magnet, series, shunt?
What power?
How complicated is the project? Just something in your garage or you want a PC controlled driver?