Hi all, I am finding myself in the position where I want to use some reasonably high power for various projects and experiments, however I don't want to have to use the grid to for example run a Tesla Coil at 1000 Watts input for fun.

I have a few options as I see it, I've got a 1000 watt (2000 surge) inverter that failed without any of the protections shutting it down, it has a pair of HF transformers with push pull primaries, each one should be able to handle 500 Watts at the appropriate frequency and output 240 v or more, so the first stage of the plan is to make a small DC to DC converter that has a three wire output ( maybe two separate two wire outputs can have the outputs stacked), a simple oscillator - driver a pair of mosfets for each transformer input and a 3 Amp FR bridge rectifier at the output and I could have a 500 Watt 240 volt DC output from each one which I could stack for a three wire supply for half bridge switching or I could parallel them for Full H Bridge switching. Of course the FWBR's would charge appropriate capacitors but not necessarily in the actual power supply, on the board with the switching circuit maybe. These little transformers are only about 30 mm x 50 mm x 50 mm so quite small.

Now a question, if I power two separate transformers from the same battery could it be more problematic than using a separate battery for each transformer since the outputs might be stacked ? I figured that the higher inverter output would exert more stress on it's primary windings and circuit due to being double the voltage if powered from the same battery. Or would it be OK to run two inverters from the same battery and stack the two 240 volts FWBR outputs ? I have four appropriately large identical batteries.

I'll post an image of the destroyed inverter circuitry, it seems one of the IRF460 mosfets at the output stage failed (the gate resistor is smoked and the driver chip exploded) then it would seem that the transformers went ballistic trying to keep supplying power and melted the IRF1404 mosfets switching them along with one of the MUR TO220 diodes. Some other resistors are smoked and another chip blew out ect., but the transformers look ok although I have not tested them yet or removed them from the board.

It used IRFP460's and IRF460's in the output H bridge. Some other good parts are still oK and I have taken some bits already. 

The idea is to build a power supply so that if it does fail I can fix it/upgrade it, I hope to ensure no operational failures by using simple protections.

With that done I would then look at using the power supplies to run HV transformers and such fun things with lots of input power of my own harnessing.

Two identical stackable stand alone units would be more useful but require more parts.

Or I could use a large center tapped steel core transformer at 400 Hz or something, but I doubt the power handling capability of the ones I have and they're too darn big.

Cheers

   

Here are some scope shots from the primary of a transformer switched at about 400 Hz, first by a half H bridge (first two shots) then the same transformer switched by a full H bridge ( I used 24 volts and two primaries in series for the full H bridge). I decided to prototype a full H bridge since I just tried a HHB and see any differences before I put the proto-board away. It's a small 20 VA toroid transformer with a 220 uF load which charges in a flash of the current needle, idle input power is very low of course.

To me the full H bridge looks better, but maybe much the same. Dead time is about 22 or so microseconds as can be easily seen in the first shots. I think I've worked out the parts list, I need a few things.

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