240VAC 60Hz split phase inverter

Dec 28, 2007 8 Replies
J

Hi,



I have a circuit with two 220Volt DC rails (+-220VDC) feeding into a



100kHz h-bridge to generate two 120VAC 60Hz rails (after LC filtering), for 240VAC split phase power.

For controlling this I think the half bridges should be controlled independently to generate each 120VAC rail. So that would be two PWM controller IC's running in parallel I guess? I was thinking of using two UC3842's for this, and feeding the voltage feedback pins



60Hz sinewave to generate the AC outputs. Is there a better way to do this? The circuitry using two of these IC's seems pretty complex.

Here's the circuit:



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cheers, Jamie


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P

You clearly need to understand what you are doing, before you hurt yourself...

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J

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thanks for the reply, I will make sure to have rubber gloves on hand during testing.

cheers, Jamie

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J

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I only gave myself one 140VAC shock (off a variac/ATX powersupply) while making this 30V to 500V input, 10V output flyback powersupply:

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so I think 240VAC will be ok, especially wearing rubber gloves this time :)

cheers, Jamie

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P

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You very clearly need to understand what you are doing, before you hurt yourself... I looked at your schematic, and what I saw was an accident waiting to happen. But, if you survive, let us know how it comes out.

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T

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Where does the +/- 220 VDC come from? How much power at 240 VCT AC do you need?

Tam

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J

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Hi,

The +/- 220 VDC is from a SMPS with a centertapped secondary fed through a rectifier and LC filtered. Maximum power at 240VAC is 3.6kW. I am thinking it would be best to do the split phases separately, with one PWM controller per half bridge, also that would allow for easily adding one more phase and put them 120 degrees apart for 3phase power.

cheers, Jamie

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T

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3.6KW is more than anyting I have done; so, Can't add anything useful there. The other point was, can't the SMPS that is generating the +/- 220 VDC output the AC instad? Connect a raised 60 Hz sine wave to the reference input, make it piece wise linear, or run it at 60 Hz and filter the output. (60 Hz transformer will probably be way too expensive).

Tam

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J

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Hi,

IF you generate the 60Hz with the SMPS that is generating the +- 220VDC, it won't be able to handle uneven phase loads as well as if the phases are generated independently, but it would be easier.. might have to do that if I can't find a good bipolar half bridge driver IC to generate each phase independently.

cheers, Jamie

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