Dear sir,
I am working on UPS, i can make 340V DC from 12V battery, now my target is to convert 340V dc to 220V 50Hz ac, but i don't know how to do it. I need help regarding this matter
Sincerly,
Zahid Islam

 

Do you need someone to design it for you or do you have an idea?

Pardon me if I'm being harsh, but I never encouraged designing for someone else's merit. Lately, this forum is getting requests on that order. I hope I'm not being uninviting.

 

I concur with Cumesoftware. This is a forum, not a design service.

If you wish to read about those concepts which will help you design and build your own inverter, I suggest Irving Gottleib's Power Supplies, Switching Regulators, Inverters, and Converters.

 

Oh, and how have you resolved the problem of cell discharge mismatch?

 

I concur with Cumesoftware. This is a forum, not a design service.
...

Or a DOD service, as I used to call it (Design on Demand).

However, why are you using 340V DC. Is there any specific reason? Since you are working on a UPS, I presume that you are getting that voltage from a battery. I think that 12V and 24V are more common in that situation, and far more easy to work with. However I see that 340V DC comes from a rectified 220V AC mains and it is understandable that you don't wish to loose efficiency. However, rectifying 220V without an isolation transformer is dangerous, if that is your case.

 

I dont have any schematics to share, but I used to repair 18 and 36 kW motor controllers for military AC units that could rectify 208v 3-phase into @300VDC, then used PWM and two hefty inductors to produce 208 3 phase again. The advantage? It could convert 50, 60, or 400Hz to 61 Hz Power. It could even (the 18 kW unit) handle a temporary loss of phase and still work! I guess they went with 61Hz out to reduce harmonic issues. The company has been since bought out, but was called Keco Industries when I worked there. Maybe if you search the internet, you can find a used or salvage unit to play with or modiify. They had some large FREDs (Fast Recovery Epitaxial Diodes), MOSFETS, and huge half wave rectifiers (3 for each phase, outputing into a common DC bus rail.) It had a soft start function for ramping a AC compressor up to speed while reducing inrush current. Anyway, just an idea.