3 phase inverter design

In message , dated Mon, 31 Jul 2006, Dave writes

These things can be obtained for money. It would be a very expensive design project to learn on. You start learning with 30 V at 1 A, otherwise you will disappear under a huge pile of zapped devices, if you don't also blow yourself up in the process.

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this is

For school of for work?? - I.M.O, if it is for work there is no point in designing such an inverter because it can be bought cheaper than it will usually cost to acquire the compontents for the prototype!

Power Electronics by Kjeld Thorborg , Prentice Hall (March 1988) , ISBN: 0136865933

Expensive - but a library library can probably get it.

It's a home project - I'll look for the book. Thanks.

For a 1 off just buy one, there are several hundred to choose from. It will likely cost you less than the price of the parts (and much less used from ebay).

Here is the 1st one I found on uk ebay, currently at 10 quid.

look on international rectifiers website.

Thanks, that looks useful.

despite the fact i am really smashed atm, you can stick you capatalistation up your arse. Any hows, i do have a 240V 10A or therabouts 1 phase to less amps 3 phase thingie with variable herz thing on the design table thing. i am in the process of trying to lay out a PCB thing, but the beer seems to delay the result. So anyways, i have a cirkoot thing that uses a PIC18F something with an International Rectumfrier IRAMS thinky that makes 3 phase motors go round in circles from a single phase thing. Hmmmm, i should find me another beer and give up. Anyhows, i need to lay out PCB and then all will smile, including my dad who is the one who wants this, yeah... The 3 phase motor is actually spinning now, but the PCb traces are way to small to be compliant. so i need to find another 100mils or thereabouts. Maybe next week.

Thanks for the pointer but unfortunately that's 230 in/out whereas I need 415V and they're rather more expensive. Besides, there's a lot more satisfaction from designing than buying - this approach may be why I rarely finish anything ;-)

That unit is what most people would call 415 out, 240 phase to neutral is

415 phase to phase.

For a 'home' job I can't imagine where you are going to get 420v single phase from (or why you would want to).

Thanks for trying to help but that inverter really is 230 input and 230 ph-ph output - normally used to drive delta-connected motors.

415 ph-ph is commonly used in machine tools with star-connected motors. 415 is easy to generate using an auto-transformer. A "standard" way to generate a synthetic 3rd phase (at 415) is to use series capacitance to the third leg of a 3ph motor; the problem is that it's only possible to fiddle the phase shift to be somewhere near right at one load condition and I need to drive a 3 speed motor (pole switched). Are you in the US? this is all fairly normal stuff in the UK.

Try

They have evaluation kits up to 3 kW, and complete schematics. It looks like the control board and power board together cost about $100 from I will be designing a special inverter for lower voltage and higher current, using PICs from They also have evaluation kits and also some good application notes on ACIMs. You can even download seminars.

I have a 480 VAC inverter rated at about 15 HP that I got on eBay. The control module was dead but I was able to locate the six optoisolators that drive the IGBTs, and I was able to generate output voltages. I powered it from a 110/440 transformer. I have not figured out the current sensing circuits yet, but I think I should be able to hook up a PIC18F2331 or similar and program it to get three phase AC. It cost $25 and a like amount for shipping. Lots of old ones like this (1989) available cheaply. I also have a very nice 2 HP GE Fuji drive (240 VAC) I got new for about $70.

Paul

If the AC adaptor doesn't say what the amperage is. 4 watts is drawing 4/12 = 333 mA (1/3 A) The resistance of the mosfet. I think the second reason is more likely, that there is no math in your crazy ranting. You will learn a lot. essential In Sales - Salespeople brings home the bacon, the rest is confusing. There's both an 8P-14, and 8PG-14. The 14 I think is rather a special part made for Satorius.

You best bet would be to start with just a screwdriver and hammer.

Google VFD (Variable Frequency Drive). There may be a few issues dealing with motors that are better addressed with these than a generic inverter. The single phase input is not typical, but it shouldn't be a show-stopper.

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Paul Hovnanian     mailto:Paul@Hovnanian.com 
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My GE Fuji AF-300 E11 Inverter is rated at 2 HP with 208 or 240 VAC three phase, but I was told that it will work at 1 HP with single phase input. This mostly is determined by the ripple in the DC link that is produced by the input rectifiers and capacitor. You might be able to push it a bit more by adding capacitance, but possibly overload the input rectifiers.

Paul