fun h bridge for winch control

I would use a huge contactor. If it absolutely has to be electronic you'll need an H-bridge driver with integrated charge pump, like this:

Then probably 8 or 12 of those, plus some discrete parts:

As you can see this gets a tad expensive. Also, you need to have some safety shut-down feature to cut power when the MOSFETs weld themselves shut. Or in case of a contactor if the contacts weld together. After all, you don't want the winch to keep cranking and then pulling your Jeep up a tree :-)

Remember, you do this on your own risk, 300 amps and so much power is dangerous.

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the fun begins!

why did you pick out a fet with a relatively low Ids? some of those ixys parts go up to 700A+. is a bank of fets better than a single fet?

That depends on the size of your wallet, lottery winnings and such. The FETs I suggested are slightly above $4 a piece. Four of these would also suffice but it'll come to a grand total of 1100 bucks because they cost $275 each:

Or this one for the "bargain price" of $150 a pop, ouch:

And then you do some outdoors stuff, get into a rain storm, lightning ... *PHUT* ... hundreds of bucks gone.

I have paralleled FETs many, many times and the reason was always the same: $$$. However, you may need resistors in series with each gate, usually something around 10ohms.

Personally I'd use the traditional big old contactor :-)

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r

Oooooh..

I'm thinking the design problems are:

Being able to turn on the fets fast enough so they dont dissipate any energy in their linear region. (requires some kind of high current driver, like the one you suggested) Being able to handle whatever inductive spikes the motor might throw our way. (not sure how to do this. (can the fet body diodes take care of this?) Handling the current

Anything else?

That's pretty much it I believe. The body diode ratings are in the datasheets. They are usually very staunch, I use the body diodes in my designs a lot.

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Contactors. Four of them. Unless the OP's winch uses a reveres gear to change directions. Or four groups of FETs.

Either way, most winches are series DC motors, with the field leads brought out separately from the armature so as to facilitate reversing polarity.

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Go to Warn's site, and download the schematics from one of their winch controllers, they are simple, using four 'starter relays' of the Ford variety, a simple switch (SPDT center off), and not much else...

Resist the urge to go solid-state... Those 'starter relays' are about $10 each at the parts store.

300 amps sems like a lot! I thought the alternator only put out 60A or so? I guess they put bigger alternators in trucks and such. I've got a small winch on my truck and just use a big rocker switch. What's wrong with a even bigger switch? It's simple.

George H.

The battery and the alternator work together to supply the current to the winch.. My winch only draws 30A under no load. But under full load (8000lbs) draws 280A.

How big of a rocker switch?? Jeez how often do you use it? Most hand operated switches would not be able to handle winch current.

Yeah this is probably the best idea. But I want to go solid state just for fun. Its a neat project dont you think?

Well, that depends :-)

You can get switches rated at 1000 amps continuous.

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Fun? I don't know. But if you implement a proper PWM you could impress your friends and tell them "Hey, I can make this huge log move at exactly 5ft per minute" :-)

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Resist the urge to use starter relays. They're not rated for continuous duty like the OEM equipment is.

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r

ve

text -

Oh I've got a small winch. I think 60 A max. (I use it to raise and lower the snow plow on the front of the truck.... Speaking of which I should check that it's all still working. Not long till the snow starts to fly.)

George H.

Well, it'll definitely be a learning experience. >:->

BTW, have you figured out the reversing thing yet? If it's a permanent magnet motor, then you just swap the poles - if it's series wound (universal), you have to swap either the armature or the field, but not both.

Personally, I wouldn't bother with a solid-state controller, unless I wanted to PWM it for torque control.

Good Luck! Rich

Aiaiai! Shades of "The Gods Must Be Crazy." (or was that TGMBC II?)

Cheers! Rich

That's not how things work with 4x4s. Its "Hey, I can drag my truck out of this mudhole which I had no business driving in to begin with at exactly 5ft per minute."

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Not suitable for the application. The winch control switch is connected to the relay box with a 10 foot (or longer) cable. This way the operator doesn't have to stan next to the winch when that 5/8 inch diam cable snaps under tension.

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