V*I is generally power. We assume Pin = Pout while designing a converter.
for a single in-out scheme its okay.
consider a single in multiple out scheme.
in is V*I say 10W
What will be output?
1. Is it overall output power 10W (pout1 + pout2)
2. Is it individual power 10W (pout1 = pout2 = 10W)
i have assumed a potential divider type load config.
Similarily what will be it for muliple in single output
and for multiple in and outs.
Yes, in DC-DC converter input power is equal to output power (with no presence of energy storage in between). And power rating of converter means, maximum value of input power without damaging converter.
1) for 1 input - 1 output: Pin = Pout + Ploss
2) for multi input - 1 output: Pin1 + Pin2 +... = Pout + Ploss
3) for 1 input - multi output: Pin= Pout1 + Pout2 +... + Ploss
4) for multi input - multi output: Pin1 + Pin2 +... = Pout1 + Pout2+... + Ploss
Dear Mr.Paul Davis,
Generally, the power output in DC-DC converter (for that matter almost all power converters) will be specified or the user "should find out" the output power before starting the design process. For multi-output converter, you must know the power that each converter "unit" needs to deliver. The net power output will be sum of all such individual units. Of course, the losses must be considered while computing the net input power required and other design issues. Hope this clarifies.
Dear Paul,
The total output power (all outputs summed) cannot be greater than the total input power (all inputs summed).
For a single input two output converter for example, if Pout1=10W and Pout2=5W the total Pin=15W + losses. The individual output power depends on the load you want to supply.
Thanks for your answers..
What if for a 2 in 2 output system. Pout1 = 10W Pout2 = 5W
Will the power input of 2 sources be like
1) Pin1+Pin2 = 15W
or
2) Pin1 = Pin2 = 15W
considering that both switches are not ON at same instant.
If both the sources are switched ON at same instants then it will be paralleling pf sources.
Neglecting the losses.
Which one should be correct 1 or 2 ???
From the circuit it seems that Vin2 will be a battery. Note that for the circuit to work properly, Vin2 has to be greater than Vin1 or at least equal.
Paralleling of the sources in this circuit is not really possible. Current sharing will not be good.
Thus, if one source is used at a time, the total power it will provide will be Pout1+Pout2=15W (regarding your example).