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High current H-Bridge


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I need to control a DC motor using PWM signal from a microcontroler. I found several componets easy to use but they are low current. The motor that I'm going to control works with 12V and 35 amps in pick. Once I will reverse it frequentily I think that I should make a project considering 35 amps nominal current.
I don't have experience in this kind of project, so that I need some help with circuits and components.

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Hello Kosoniscs
  35amps wow, your talking 10 or 8 gage wire. A pcb couldln't handle that kind of current so you would have to build it in modules using isolators. I'm thinking three modules. One for the low curent comos controllers, second for chopping the curent, and third for relays to handle the current. The third one would be the hardiest because you would have to find fast switching relays that you could hard wire togeather. I'm guessing that if you hang in on this site the real smart electronic guys  will come up with something.
                                  Good luck gogo

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It may also be possible to use two starter motor relays to change the polarity, and only one MOSFET as PWM motor driver. Just throwing in my dumpster diving rock bottom penny broke approach.

And if you insist on using an H-Bridge, then you may find these links usefull:

Power control, with H-Bridge concepts and schematics in design:

H-Bridge Controller IC for Automotive DC Motors (Datasheet is also available):

Brief H-Bridge Theory of Operation (Good links):

Voltage Spikes in FET based H-bridges - By Chuck McManis - 2002 (Please read this, very informative !):

Motor and General Control Schematics (Links to some good sites):

You can also Google: "MOSFET H-Bridge Schematic"


Many designs I have seen on the Internet lack sufficient protection of MOSFET's against induction spikes caused by the Motor. They are easily destroyed by insufficient precautions against this, especially via feedback into the Gate of the MOSFET.

Success with your project !


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