How do you control the speed of pmdc motor using pwm?


iceng5 years ago
PWM ( Pulse Width Modulation ) is the method of pulsing a DC Motor so very
rapidly that the mechanical inertia of the motor armature like a spinning top
continues to turn when another pulse adds DC rotational energy to the motor.

If we vary the width of the pulse ( say Wider ) the average motor energy increases and the motor speeds up ( turns faster )..

If we shorten the the pulse width the average motor energy decreases and the
motor slows down ( turns slower ).

Now you ask,
why do all this pulse work
when simply changing voltage can change motor speed ? ?

Well the motor pulses are full voltage, and the motor may be slow
but it will have the torque of a full voltage motor even at low speed :-)

A
Only if full current flows during the on period.
And inductance stops that.
Steve
Ive wanted to make a pwm generator for my heater blower in my car.
Theyre pretty cheap & seem worth buying. I just want to be able & know how...
Err. You connect the motor to the PWM generator, and vary the duty cycle.
Simples.

Steve