What is the best topology for a 1500W OFFLINE supply/charger?

Are you allowed to let ripple appear at the batteries when they are being charged? If so, the design can be a lot simpler. Normally you would have to have quite a lot of capacitive storage.

PFC is usually done as a booster. The switching transistor requirements in the PFC stage are easier to meet if the section is making just a little more output voltage than the peak of the input.

A voltage fed push-pull forward converter is likely to be the best for the isolated section. The current fed topology has no advantage when a single output is being made. Flyback requires too much of an inductor at these powers.

What is the output voltage? The type of rectifier you use will depend a lot on that.

Push-pull with synchroneous rectification. There are a number of application notes and a bunch of datasheets at the linear technology and various other manufacturers. Have a look at the LT1922 for some intros.

Rene

Fifteen hundred watts, at 220 VAC line? That's less than ten amps. If you're charging 24V batteries, that's still only 62.5 amps. For a battery charger jock, that's trivial. What's the hangup?

I used to work for these guys, who make battery chargers and aircraft power units:

Good Luck! Rich (If you tell them "Rich sent me," please note that my surname is pronounced, "Gryce" in English, or "Greiss", in German. Thanks! :-) )

Dear Mr. Rene and Ken Thanks for your response, I would like to clarify the queries as follows The battery voltage is in the range of 48 to 72Vdc and I am allowing the ripple to appear at batteries while charging. But I must be able to reduce the current to twinkle (when batteries are charged). As you have mentioned PFC is done as boost converter, but it does not provide isolation. What I am trying to do is to use single stage that would provide PFC ( > 0.9 would do) as well as isolation so that the system would be simple. In this power range IGBTs are more feasible, so I would like to use ZCS (zero current switching) to be able to operate in 100KHz range. This will also reduce noise and its related issues. I have looked at LT9112. It does not has built-in driver and is basically designed for low voltage output. I am thinking more on the lines of parallel synchronous ZCS switcher on full or half bridge topology using IGBTs Regards Imran