Does anyone knows how Battery charging in 800VAUPS

[samson.bunty1986]

Dear all,

Does anyone knows how a charging circuit designed in 800VA UPS?? I Know some what like, they will step down the 230VAC to some 15VAC and fed to mosfets. Will the charging done through drain-source diodes??? Is it so????kindly explain me how the charging happens in UPS.

 

[tpetar]

See this edaboard thread :

https://www.edaboard.com/threads/143790/


Often manufacturers use separated diode in gretz with some linear regulator such is LM317 to charge smaller batteries for smaller UPS. The form constant voltage example like 13,8V float charge. On trafo is separated windings just for charging like 18V with example 2A.


Search edaboard there is lots of circuit of inverters and UPS, you can analize circuit, there is one example :

http://www.8085projects.info/image.asp?picture=APC BACK-UPS circuit diagram.jpg

 

[samson.bunty1986]

hi tpetar,

Thanks for your reply.

The LM317 is used for 2A charging where we can use for PC back up. But,i was interested to know how the manufacturers of high capacity UPS are making the charging circuit for 12V,100AH or 150AH lead acid batteries. Please clarify my doubt.

 

[tpetar]

LM317 is limited to 1,5A current. Often UPS battery charged at 0,7A rate. Principe is the same for larger battery bank, but not with LM317, they use other parts for charging circuit to get 13,8V at higher current.

 

[samson.bunty1986]

Hi tpetar,

Correct,I have seen in my PC back up UPS. They have used LM317. For higher currents can they charge the batteries with P55N06 Mosfets????

Why am asking this is, I have seen an UPS which can charge 12V ,100AH battery with 10A. But they have connected Battery +ve terminal directly to Centre-tap Tranformer . On each end of that winding 4mosfets drain (Each Side)is connected(Total 8 mosfets both ends). The source of all mosfets are connected to B-ve terminal. Kindly help me why they have connected like that???is it for charging???

 

[tpetar]

MOSFET and battery are connected like that for UPS/Inverter purposes. For charging needs its possible to use MOSFET diodes but I think its better to make this with additional diodes/gretz and regulator.

Circuit if you have for that UPS will help explanation.

Best starting point is to see other UPS/inverter circuit, just search edaboard.

 

[samson.bunty1986]

Tpetar,

Can you please tell me What does gretz means??

I have searched edaboard for UPS charing circuit. But i dint get anywhere. Only Inverter circuits are there. But i understood about Inverter working. I just want to know the charging concept of high current charging.

 

[tpetar]

Diode in gretz configuration for full wave rectifying (gretz have four diodes) :

https://upload.wikimedia.org/wikipe...ge_alt_1.svg/557px-Diode_bridge_alt_1.svg.png


https://en.wikipedia.org/wiki/Diode_bridge

 

[samson.bunty1986]

ohhh...u mean bridge rectifier???? ok ok..thanks

 

[samson.bunty1986]

Please help me to understand how the charging happend in higher capacity UPS??? (Not for PC UPS). For a battery 12V,100AH. With charging current 10A at starting.