nickskethisniks said  

I can be wrong, but A quick look at the  bottom of your PCB and the position of your gate resistors/components indicate wrong connections,

Just about everything I posted before WAS wrong and I have not found a way to delete it. I have everything now exactly as the example "wiseguy" posted for me. The only changes I made are noted in my last post. I`m sure I have it all wired correctly now. I get good results up to 150vdc input.

Now is the time to implement the EGS002 changes for their less thanperfect overcurrent behaviour.

I will post some links later if you need them - as I have ties for the next day or so but their is plenty of information on the BS and the net on what changes need to be made if you do some searches.

There are products out there that use the EGS002 and they apparently work well without the mods being made, there must be a secret about how they do it.  But as you have found  like many others here that the mods are required to stop FETs blowing.

I believe this is accurate now.

Ok, sorry, my bad, I forgot that part apparently...

Did the irf740 mosfets blow without load? Maybe your layout is not optimal (you can't expect good things when combining power and high frequencies on a protoboard) that there are high voltage spikes over drain/source or on the gates. Chance is that higher voltage rated mosfets could survive that, but this would not take away the cause.

You want to probe the gate/source and drain/source of the mosfets, also look for cross conduction but this will be hard without the right tools.

  nickskethisniks said  

also look for cross conduction but this will be hard without the right tools.

I blew all my 46NF30 and IRF740s with a load and without. The IRFP460n were just a cheap ebay find and I have not tried them yet but would expect to blow them too if I don`t solve my problem 1st. I have learned so much just on this thread and my component placement is far from ideal. No doubt I have a lot of cross conduction. I might just start all over and build it right this time. I was looking for something simple to just play around with my gen project but if I can`t make it work I would try a wiseguy build or a ozinverter or something else. Maybe use a transformer. I`m open to all suggestions from all here.

Poida showed what he did to the EGS002 card to stop it blowing mosfets  here

I would not give up yet without first trying the EGS002 Mods.

There is another entry by "Tinker" now Murphy Friend on how to Mod the card - I can't advise if they are the same or if one is better than the other - I have never modded a card.
Tinker mods are here

So hopefully someone else can advise you of the best method to make your EGS002 FET friendly.  Whilst your breadboard may not be the neatest, I do not believe it is what is stopping you from generating AC instead of just dead FETs.

  wiseguy said  

Now is the time to implement the EGS002 changes for their less thanperfect overcurrent behaviour.....

....their is plenty of information on the BS and the net on what changes need to be made if you do some searches..

I took your advise and did find much info on other sites dealing with issues like mine. I have a notepad full of things to try and ways to test I was unaware of. I will study the links you provided and the next time I post I will know more based on newly acquired info. Keep the advise coming. I pay attention. Thanks everyone !

If FET's are blowing without a load consistently then it's possible the dead-time is too short for the FET's.  Perhaps you should set the dead-time on the egs002 to max for now.  It's difficult to know for sure unless you can scope the uppper and lower FET's simultaneously.

Also, be aware that, unlike the common usage of egs002 on this forum, you are using it for direct high voltage switching which is risky given that there is not adequate creepage and clearance between the high and low voltage pins.
Edited 2024-05-12 04:52 by analog8484

Much good news to report for today. After unsoldering a few things and testing all my runs with an ohm meter I proceeded with the "poida fix" provided in the link. Bingo.. solved most of my issues. "rusty" told me about this 2 weeks ago but I didn`t have a spare board at the time. Wish I would have done it then, I could have saved myself a few bucks. I am now able to reach my target input voltage of 175-180vdc. Trim pot is to the gnd. side and I have 28vac with a 40watt bulb as a load. Pin15 is at 4.5vdc. Bulb is glowing orange. Slowly, I turn the pot and increase my AC to about 60-65 vac. Bulb is bright, waveform is stable.  Nothing getting warm. Pin15 is now at 2.8vdc. Turn the pot more to about 70vac and pin15 is down to just under 2vdc. Go just a little more and pin15 drops to 1.5-1.8vdc and the board shuts down.  Haven`t blown a single fet (IRF740) all day.  I am certain the remaining issue is in the control circuit now. R19 is at 100K. For R21 I began with a 56K with some control. I tried 68K and it was worse with very little control. I have a 50k in there now. Should I try a 47 or 43K next ? I did quite a bit of testing, although nothing to drastic. Ramp the voltage up and down, applied the load on and off at various voltages. No issues. Max amps never exceeded 1 amp. I would expect thing to heat up a bit as I add more power and load when I get the IRFP460 mosfets. Very encouraging day. Almost there !

  wiseguy said  

There is another entry by "Tinker" now Murphy Friend on how to Mod the card - I can't advise if they are the same or if one is better than the other - I have never modded a card.
Tinker mods are here

Well, that link goes back many years . I do remember that the EGS002 mod worked well but I would not consider the schematic shown - we, the forum here, have moved on by a long way since back then.
There are still some EGS002 boards in the bottom of my old projects box but I would not dream about using them now. The new inverter designs here are much more reliable (they only blow up if one does something stupid like shorting something) .

Can you post a picture of the inductor you used?
I can't believe changing the resistor will do much at this point.

  nickskethisniks said  

Can you post a picture of the inductor you used?
I can't believe changing the resistor will do much at this point.

I admit I don`t know a thing about chokes. Bought this one because it will handle 10 amps and was rated 3.3mH. Didn`t know how to hook it up either. Got only 1 side wired in series now. Tried wiring the other side in with jumpers and also bifilar (that totally changed the waveform). This choke is probably wrong. I could make about what ever I need as I got a lot of small ferrite torrids. I just know as I turn the AC voltage higher,pin 15 decreases in voltage till the board drops out.



 
Edited 2024-05-13 01:41 by ramblin

It looks like you have a common mode choke, this one will have a very low saturation point/current, they can't store a lot of energy and this function is what you want. So this would probably mean why you are blowing up mosfets. Saturation means no inductance and so just a piece of wire, and high current peaks thru your mosfets as result, because of the 2,2uf on the output, this forms a very low impedance/resistance for the 10khz H-bridge output.

Find something with iron powder or better sendust material, or gapped ferrite cores.
It has a lot more windings, 100windings are very common most of the time and they can store energy, crude said to fill the gaps of the pwm.

Most info on this site about inductors are in the inverter or mppt controller threads, but the used inductance is much lower.  

This manufacturer has lots of goodies:
https://www.micrometals.com/

For example MS-184075-2 is a common used core material used for this kind of application, although 10khz is low and you might better of with a gaped silicon steel core, most often used in grid tied inverters.

We would need some numbers to help you make a decision, I think voltage/current output and switching frequency are the mean parameters we need to calculate something for you.

Or you said earlier you have some things laying around, look for some cores in a scrap bin and post some pictures, maybe there is something usable.
Edited 2024-05-13 06:23 by nickskethisniks

I knew I messed up on the choke. With that explanation I see how bad. Most of my surplus are going to be ferrites (lots of ferrites) about the same size as pictured now. But I do have these big ones. (2) 18 ga. steel, 150 strips each, insulated on 1 side, at 1.5 lbs apiece.   And this Micrometals, T650-52 powdered iron toroid.  On a chance it could be used as is, Its wrapped 1st with 130 turns of 16 ga. solid copper, silver plated, teflon coated wire. 2nd wrap is (3) evenly spaced (120deg.) of 20 ga. solid copper, silver plated, teflon coated, 41 turns each (could be tied together) for total 123 turns.

That T650-52 core should work ok, try 10 turns of suitably thick copper wire for the primary current you are expecting, 10T gives approx 40uH. Leave the other wires there disconnected if you want to use them for some other purpose.

Cheers
Mike

That 650 core gives 405nH/n^2, formula is L=405 X n^2
130 windings will give you almost 7mH, 82 windings wil give you 2.7mH

Inductance will drop a bit when loaded but the core you have is a monster so this will be peanuts.

If your not rewinding it, you could do like mike suggested, wind over the existing windings or use 82 (41+41 in series) windings this will be good for testing. Later on you can try something different this will have probably higher  no load losses Vs a smaller (optimised one)because it's 5kg.