ac load switching

[libra]

I am trying to pwm the ac output from the wind genny(before the recitfier) as a means of controlling the genny rpm (along with the furling). This genny will be able to generate high amps. I can find 10amp triacs but nothing much larger. Is there another way to pwm the wild ac that others have used?

I would appreciate some guidance.

Libra

[cyplesma]

my first thought(without putting too much brain power into it), but maybe too late since your genny maybe already together, or at least the coils.

but maybe make the coils go a higher voltage so the amps will be less.

[dinges]

TIC263 triacs can handle 25A, from memory.

Here's the datasheet. Yes, 25A:

http://www.datasheetarchive.com/datasheet.php?article=3281561

Should be easy to get, at least, I've never had problems obtaining them. Almost as common as the TIC216 and TIC226

Larger ones probably exist too; check out farnell.com (in Europe).

Peter.

[SamoaPower]

A triac is like two SCRs in parallel with opposite polarity.

Most high power control circuits use SCRs because they can be obtained with high current ratings up to hundreds of amperes.

I think the trend today is to use FETs instead.

[ghurd]

I wondered about using triacs to fire fets...

G-

[Opera House]

Voltage losses are in this order  Worst TRIAC, SCR, TRANSISTOR, FET  Best.

[BigBreaker]

I've been mulling over a design that would use caps and FETs on wild three phase to make synchronous 120V 60hz AC and battery level DC with any surplus.  It's non trivial of course, but potentially very efficient and robust.

Remember that anything inefficient will generate a lot of heat and you'll need to dump that heat somehow-somewhere.

[pemtek]

Why do you want to switch the AC?

Surely using a high current bridge and some fets would be cheapest and easiest?

High current bridges are cheap and fets are also cheap and easier to switch than driving a bank of thyristors.

[libra]

I guess I have not made myself entirely clear. I still have a 100 amp rectifier but thought that switching the ac when shutting the genny down or as a safety feature if there were high amps ( say 50 amps on a 24v system) the pic would pulse the genny and slow it down. Yes, I will still have the furling tail but this would be a backup.

I read the mail and have seen others where the high amps have burnt the stator.

I could pulse the  rectified dc but thought that this would be easier on the diodes etc.

Appreciate learning what others have found best.

Libra