DC Motor

AFAIK, any dc motor as long as you don't exceed the current rating.

http://www.electronics-tutorials.ws/blog/pulse-width-modulation.html

Thanks! I am looking atbanradiator fan motor that I want to speed up as the temp climbs.

You have absolutely no idea about this topic, do you?

Larger power dc units should need interface. PWM could be the simplest frequency drive, you know.

I have a just little, you know.

This kid has guts.

PWM and IGBT interface for a drive

That's what I was thinking, but it confused me cause some mfgs advertise their fans as proportional and others don't mention it.

I have to assume a few points because you neglected to tell us:-

1) The fan you want to use is a nominal vehicle 12 volt version.

2) The vehicle system voltage is 12 volts

3a) you want to increase the voltage from the PWM to the motor to increase speed further...

OR

3b) You want to control the fan's speed using a PWM between say half and full speed.

The point 3a) above will usually overheat the motor and seriously reduce motor life.

The point 3b) above will usually work far better. The motor size and the amount of air moved needs to be adequate at the "low speed" point. Maybe a larger fan and or motor will be required to achieve that....

Due to a serious lack of information from the OP, my guesses above could be way off....

Like the old saying GIGO!! Garbage In, Garbage Out!!

Make sure that the motor used can easily handle the current and the load placed upon it!!

Excellent guess work there....or not.

I'm thinking along the same lines, although why and exactly what is still being kept very secret by the OP.

Sometimes I feel like CR4 is mistaken as a community of virtual clairvoyants.....

Some guesses are priceless.

Your assumptions are correct, and I am working with scenario 3(b). I just want to proportionally speed the motor up to what it's is capable of (rated current). I understand I need to size the fan for the HP needed and CMF needed to keep the application from failing. The questions still holds true even without his in formation. Can any DC motor be driven with a PWM to achieve proportional rpm? Thanks.

OK, you're going to insist on a simple answer with minimal information given. Here you go. Here's my answer:

NO! One should not drive any DC motor with any PWM driver circuit.

Now I guess you will ask me for more information. Sorry, but my answer is still no.

You know google and youtube, has lots of info about it. I think you are capable of doing research by the way you post.

You start always with the demand CFM, then the fan then the fan motor, then your driver (PWM or Inverter- this does depend on size)

Off the top of my head;

The PWM frequency should be at least 5x the commutation rate; there should be a minimum of 5 PWM pulses when a brush is on any commutation contact as the motor spins. If not you will get "motor boating" of the motor; the motor speed will vary periodically at some sub-harmonic of the combination of the commutation and PWM frequencies, usually very noticeable but not dangerous.

Or add some capacitance to the output of the PWM generator to smooth the waveform

"Can all DC motors be driven variably with a PWM" No.

Some DC motor designs will not tolerate Pulse Width Modulation control.

This can result in erratic motor speed and/or catastrophic motor failure depending on motor load, motor speed, and applied voltage level.

Contact the motor OEM for correct, safe answers to your questions.

If you choose not to contact the OEM and instead decide to experiment, be sure to wear appropriate personal protective equipment and properly guard the experiment so that no personnel are exposed to risk during testing of the motor.

Keep in mind that some symptoms of motor failure may be significantly delayed so be sure the test method and test time length matches the application requirements.

Good luck and stay safe!

• Don't do it with a series-wound motor.
• Bear in mind that all a PWM control does is reduce the speed of the motor below its maximum speed.
• An on-off control, much as is used on vehicle cooling systems and room temperature regulation ("thermostat"), may be all that is needed.