Solar Power Inverter (transformer-less) - DC/DC Boost Converter

[binaryninja]

First off, I know there are several posts on this topic. I wanted to start a new thread, as many of them are old posts, and I'm looking for new info.

Secondly, is anyone familiar with TI's C2000 Renewable Energy Kit? It has a boost converter on the front-end, uses a IPM (intelligent power module), and the c2000 mcu. It's capable of 20Vdc max input from a renewable source (PV/battery) and outputs 24Vac/40W.

More importantly, I have been given the task to use the above kit as an example/ starting point to design an inverter that will have inputs from PV (up to 50Vdc) or a 12Vdc battery and output 110/60Hz and 220/50Hz AC @ 200W.

My question: Is it possible to boost a voltage from 1-50Vdc to approx. 311Vdc or 155Vdc (peak values) for input to the IPM? Using the exact boost circuit that TI uses results in a max duty cycle of almost 95%. That surely is too high. The customer wishes to keep it transformer-less. Is there any way to make this work? Also, am I correct about the input voltages to the IPM (is it peak voltage or peak-to-peak)?

I am still learning about solar power inversion and SMPS in general... please give me some insight.

 

[kabiru]

Hi,i think it's more preferable to use the boost converter to step the voltage from 12volt to 115volt then you can use h-bridge arrangement and drive your output which is going to be Ac signal 50-60Hz.

 

[dick_freebird]

You may get to "transformerless" but you will not get to
"inductorless" with any kind of efficiency or current throw.
And transformers do get you past all kinds of safety-regs
nastiness. If it's about the pennies, you need a better
class of customer.

 

[youcef2010]

Dear Binaryninja,
Some module already include a boost converter and an inverter, would you chech the attached pdf file

 

[mtwieg]

The lower your input voltage is, the harder it gets without a transformer (or tapped inductor). Getting a voltage multiplication of x10 generally is feasible, but when you get up to x20, then you start to lost efficiency, especially if your switching frequency is high.

If you want to do a step up ratio much greater than x10, you should consider using a transformer. If the transformer doesn't need to provide isolation (I think that's true in your case?), then that makes things much simpler, and your efficiency is less likely to suffer.