PWM dc motor speed controller that controll motor in both direction

[mtech]

Hi!


I need some PWM controller, that can controll motor to run in booth
direction, best would be when potmeter is in middle that motor stands, and
when we changing potmeter to each side so motor speed up in each side.


I did allready do soemthing with H bridge but mosfet's died when I put load
on it, I need smeting that could hand 10 or less A on 24V.

Thanks,

Marin

 

[mtech]

The H bridge is the correct approach. You need to figure out why things
are failing.

Check the specs on the MOSFETs to see if they need external diodes or
snubber circuits for inductive spike protection.

I did but they still fail, probably because opposite mosfet's get's some on
gate because of inductance load.

Make sure the MOSFET
drive is sufficient to turn them on quickly. Also, make sure you don't
hook up the supply backwards.

This was going from LM324 OP amp, I also did try to add tranzistors, looks
better but still same. What is you're advice about driving it?

 

[mtech]

http://www.mouser.com/Search/Refine.aspx?Ntt=*Hbridge*+*driver*&N=1323

Pick one that suits your needs.

I think none:

NO RESULTS FOUND.

 

[petrus bitbyter]

I think none:

NO RESULTS FOUND.

Just click one more on the Search button.

One other thing: You'll need to be sure that under no circumstances the high
and the low FET on the same side of the bridge conduct at the same time.
This causes a short that may fry the FETs in a very short time. Commercial
bridge drivers usually has a protection build in.

petrus bitbyter

 

[[email protected]]

Right. If one knows what they are doing, one can incorporate this into
their own design. OTOH, if someone needs me to push the 'Search' button
for them, use a commecial part. ;-)

One thing to be aware of is that you can't drive your PWM to 100% if
your high side drive
is derived via a bootstrap cap on the output. ie IR2104 driver. The
highside drive voltage will fall
and your fet will start to go into it's linear region and get VERY
hot before letting out the smoke :0)
On an 8-bit pwm I've run up to 253 out of 255 (20KHz) no problem , so
it's not as if you are loosing a lot of power
because you can't run 100%

Cheers
Rob

 

[[email protected]]

Right. If one knows what they are doing, one can incorporate this into
their own design. OTOH, if someone needs me to push the 'Search' button
for them, use a commecial part. ;-)

One thing to be aware of. If using a high side driver that uses a
bootstrap cap from the output (ie: IR2104)
you can't run your PWM to 100% If you do the output drive for the
highside will fall away and your FET will
start to be driven into it's linear region. Not a great idea if you
want to keep the smoke inside!!
I've run the PWM to 253 out of 255(8 bit) at 20Khz no problem.
cheers
Rob