Question about online UPS

[Jetach]

I was just wondering if an online UPS uses a transformer?

I know the line interactive UPS does, but I was not too sure about the online UPS. I need a UPS that can supply 2kW for about 30 minutes.

The transformer acts as a voltage regulator correct? I am a little confused, any information about this would be helpful.

 

[HMS1021]

A transformer is not a regulator.
Say I have 100v and want to light a 5v light bulb.
1.) I could use a resistor but it would get hot wasting a lot of power to drop 95v.
2.) I can wind 100 turn of wire on the 100v side and 5 turns on the output and this will give me my 5v and this is a transformer. They can be over 98% efficient but with lots of copper wire and an iron core can be both heavy and expensive.
3.) The third option is I can switch on the 100v for 5% of the time and off for 95% and with some capacitors and inductors smooth the on off pulse into a steady 5v to light my bulb. Switching power supplies can be 98% efficient. They can also be light and low cost. Since there is switching the switching noise, while filtered, can make a transformer preferable in some application.

Of the 3 only 2 works well in reverse. What's this have to do with a UPS? To have your 2kv for 30 sec you must store the power. The two common technologies are batteries and possibly capacitors. Both technologies are low voltage and DC.
So, you have a 12v battery but want 2kv. You will need a transformer with a 167:1 turn ratio, actually a few more due to losses. Transformers require AC so you will need switching devices to switch the battery voltage. If you need precisely 2kv it is efficient to sense the 2kv and use that to control the on to off ratio of the switching circuit associated with the battery. This is called regulation.

Ps you will likely want to keep the 12v battery charged using 110v or 220v so see 2 or 3 above.

 

[poweraces]

most of the ON-line UPS now they don't use transformer (xfomerless) specially from 1KV-15kv or 20KVA single phase On-line ups, instead of transformer hey used IGBT. If you need 2KW for 30min theirs a lot of On-line UPS in the market.

 

[Jetach]

most of the ON-line UPS now they don't use transformer (xfomerless) specially from 1KV-15kv or 20KVA single phase On-line ups, instead of transformer hey used IGBT. If you need 2KW for 30min theirs a lot of On-line UPS in the market.

How does an IGBT take over that of a transformer? I'm sure there are drawbacks and benefits for using each one.

 

[ALERTLINKS]

You can skip transformer if your DC_bus volage is relative to required AC output. IGBT's are only used for convering DC to AC.

 

[poweraces]

How does an IGBT take over that of a transformer? I'm sure there are drawbacks and benefits for using each one.

from the article: Transformerless UPS systems utilize Insulated Gate Bipolar Transistor (IGBT) for all power conversion processes (AC/DC converter, DC/DC chopper and the DC/AC inverter). IGBTs are much faster than the traditional thyristor and can be controlled by simply toggling an on/off gate signal using a digital signal processor and a field programmable gate array as opposed to waiting for a zero crossing. When the gate signal is removed, the IGBT turns off. The combination creates a series of pulses to re-shape existing voltages (conversion from AC to DC and from DC back to AC)