Hi All
I am looking at creating a cascaded boost converter (Power 300W) (two boost converters), the first of which takes in 12V and outputs 50V @ 6A and the second takes in the 50V and outputs 120V @ 2.5A. I was thinking of using the following controller to do this from TI: LM5022. I wanted to enquire firstly if this is a good idea, if not has anyone got any suggestions?

I also wanted to enquire about inductor and capacitor choices I have followed the worked example and seem to be getting very unusual current values for an inductor I'm getting a peak current of near 100A which seems really unusual to me when comparing this with an online calculator from coil craft I get a much lower peak current around 25/26A, can anyone suggest which value I should trust, (I copied the switching frequency from the example of 500kHz). I also wanted to enquire what approach I should take with regards to selecting capacitors anyone have any suggestions for this? Any help would be greatly appreciated.

Kind Regards

Art

 

Why two cascaded converters?

 

Why two cascaded converters?

It was a topology that was recommended

 

Why two cascaded converters?

Do you not think it's suitable? I'm trying to find a way I can do this easily with a boost driver IC, if you have any suggestions they would be warmly welcome

 

I would go with a TL494 and a push-pull output with a transformer 10:1 ratio or slightly more , problem is that 300W is going to take 25Amp or more on 12V ..

 

Do you not think it's suitable?

I woukd have thought a ten times step-up could be achieved more easily with a single converter..... but I have no practical experience of building them, so other members here are bettter placed to advise you.

 

It might be worth looking of the possibility of using a ready made 12 volt DC to 110 AC converter and modifying it. They work by first stepping the 12 volt DC up to a DC voltage somewhat higher than 110 volts. The switching is done at this high voltage to generate the stepped waveform to imitate the RMS value of a sine wave. I suspect (But don't know.) that the DC voltage is not as high as the peak value of a sine wave. The DC before it is converted to the stepped AC might be near the voltage you want.

Les.