OK, I've read this thread every day, and after about 30 seconds, my mind goes to blah blah blah.
Might as well get something out of it, so QUESTIONS:
1. What the heck is PWM -- I can read the words, but WHY would anyone want a PWM?
2. Is PWM what gives a "slow start" to a fan?
3. How do you know if you have a brushless fan motor?
4. When would I want PWM?
5. How do I know if I have a PWM?
6. Is the Dakota Digital PAC-2700 fan controller a PWM?
Thanks.
It doesn't vary the voltage, it varies the duty cycle of the voltage, i.e. square wave, 0-12V
1. PWM = Pulse Width Modulation as in the sentence above. Why? Variable speed control.
2. Not necessarily, but is usually part of the design of a PWM controller. It is referred to as a "soft start".
3. Google the part number.
There are 4 main types of DC motors:
- Permanent Magnet DC Motors. The permanent magnet motor uses a permanent magnet to create field flux. ...
- Series DC Motors. In a series DC motor, the field is wound with a few turns of a large wire carrying the full armature current. ...
- Shunt DC Motors. ...
- Compound DC Motors.
4. When you want to vary the speed according to temperature.
5. Don't know what you know or don't know.
6. If it's variable speed, it's PWM. Variable as in ~10 rpm to max rpm & anywhere in between.
BTW#1, this is not an online class in electrical engineering even if I am qualified to teach it, which I am (LOL).
Google "PWM dc electric motor", then you can teach the class.
1st hit on Google:
BTW#2 Electric cars use AC motors. The battery voltage must be converted from DC to AC. Speed control is not PWM.
The two primary ways to
control the speed of a single-
phase AC motor is to either change the frequency of the line voltage the
motor sees or by changing the voltage seen by the
motor, thereby changing the rotational
speed of the
motor.
Electric cars & all industrial equipment use 3-phase electric motors. Lesson #2, some other time.
BTW#3 Your alternator is a poly-phase (more than 3) generator. A motor can be a generator & a generator an become a motor. Electricity can create magnetism & conversely, magnetism can create electricity. High school physics.