Renewable Energy Questions/Discussion > Automation, Controls, Inverters, MPPT, etc

Inverter Build Project.

(1/5) > >>

welshman:
As a backup inverter I plan on utilizing this casing and transformer.

I've been brainstorming lately on how to build a power board / mosfet circuit and i think i've come up with something that is new and should be interesting to see.

over the coming weeks i'll be putting this together and documenting it's build.

this is what im starting with.

Pete:
I am interested in how much Idle current that type of transformer draws. Old welding transformers like that are pretty easy to come by these days with everyone going for inverter welders. They may work out well for inverter builds. Just wondering about the looseness of the magnetic circuit and if they have horrendous idle currents.
Good luck
Pete

ClockmanFrance:
I have had a APC UPS 5000va, that would self start and would give about 3.7kw of 240vac from my 1100ah 48v battery bank.

The problem was that type of sheet laminate EW transformer was eating 200 watts from my precious batteries just running.

Now days i use a toroid wound core, and with suitable Ferrite Choke my new OzInverter Inverter now only uses about 30 watts, so far more efficient using a toroid core.

However, toroid cores and the Inverter power board need to soft start.

welshman:
ill let you all know what i get up to and how it performs.. i've ordered all the bits needed and drawn up the pbd in eagle and had it printed by pcbway. just waiting for everything to arrive. im going to try to take a few lessons learnt with the other inverter and put them into practice with this "backup" device.

the mosfet board design i've gone with is quite a bit different to the normal.  i've made sure that each pwm to the mosfets has exactly the same length of signal wire so the timings of the chips should be in sync a bit better.

the actually mosfet bridge will be something im sure you will like to look at, like i said its a radical design, fingers crossed that it makes sense in the end.


i've ripped up and inspected the relay on two powerjack control boards now and it looks like they are the culprit when blowing up mosfets. my figuring is, due to the dirty contacts on the relay, when the generator stops and slows down the pj is supposed to open the relay to hand the mains back to the inverter. but if the relay doesnt break fully and is noisy. the generator as it slows down is going to get its decaying sine imprinted slightly on the inverters own sine. iv'e bought a 100amp solid state relay to replace the standard one. the state of the contacts on the standard relay is bad enough to be causing a problem on its own. maybe it's why it took many years of switching on and off between inverter and charge multiple times times a day before it blew the first set of mosfets. who knows?

Pete:
Sounds like a good plan to swap the relays with a Solid State Relay. There may be a problem with time lag in the relays too.
Just wondering if you are going to put some delay in the SSR relay switching times to match the mechanical relays or whether you think the faster switching will not upset the mosfets more.
Look forward to reading about the build
Pete

Navigation

[0] Message Index

[#] Next page