Isolated MPPT DC DC Converter

[abhinand rd]

Hello,

I want to design an isolated DC DC converter for MPPT stage of solar system.

Output Power: 7kW

Input Voltage 14V-57V

Output Voltage = 12/24/48 Configurable based on the battery.

I am confused as to which topology I need to go with.

Is phase shifted full bridge converter a good choice?

I checked flyback buck boost converter, Can a reliable flyback converter be designed to handle 7kW power.

Can anyone please help me arrive at a correct topology for this application and any reference design if possible.



Thanks!

 

[Easy peasy]

Interesting requirement - do you realise 7kW @ 14VDC in is 500 amps ?

and you want variable output voltages too - at 12V out, 7kW = 583 amps DC, 48V = 146A DC

so the output has to be able to go from 12VDC to 48VDC AND 583A to 146A

Perhaps you could do 14 x 500W flybacks ? each up to 36ADC in and 42ADC out ... ? ( not such a great idea )

A pre-ceeding step up stage or stages to 75V say, sounds like a good idea,

So 5 x 100A boosters to get you to 75V, then a phased array of buck converters, say 10 of, to provide the 583ADC @ 12V, or 146ADC @ 48V

Or, if you want isolated, say 10 x resonant H bridges, to provide the 583ADC / 12V to 146ADC/48VDC

kind regards,

 

[cupoftea]

Yes, as Easy Peasy says with the Boosters then bucks...

With the Bucks, you need a lot in parallel...so i would simply give them all an output voltage demand which falls with output current....ie, 25V demand when on light load, but say 23V demand when on full load.....if they all have this algorithm, then you can happily parallel them, and they will all share very well the load current....but if you need exactly 24V than of course you cannot do this.

Then there are other ways of paralleleing.... you could simply make each have an output current limiter which limits at "maximum current"......then they will all end up sharing in the end....though one "odd one out" might be on light load while all the others are pumping away at their max load.....probably doesnt really matter (?).

Of course, other ways of paralleling are master/slave, ...or one error amplifier guiding all of them.....or transconductance error amplifiers in each...whhose outputs can be connected together since they are current sources.

So yes.....paralleled converters seems the way for you

 

[Easy peasy]

Bucks was an example, the OP wants isolated,

a 10 phase boost converter, followed by a 10 phase resonant down converter would be an elegant solution, each single stage is easy to assemble and test independent of the others.

You could have 10 x isolated Cuk converters - but I don't recommend.