Hi everyone,

We want to charge a static battery pack (around 100kWh, 680VDC nominal) from our solar array (40kWc 750VDC line bus controlled by the inverter which communicates to the power optimizers).

So one way to do it is to have a DC/DC on the 750VDC bus and make the voltage go down appropriately while controlling the current.
While that seems the right thing to do, we were wondering if just chopping the voltage with a MOSFET (Si, SiC) or IGBT would be an option?

Excuse my ignorance but what would be the problems involved? Current spikes at each "chop"? Voltage spikes?

If we also control the current (with a hall effect sensor for example), can we even think of doing a current control?

Thanks for the education!

Marc

P.S : we've actually done it on a small scale with a current limiting resistor and at small power (<10A @ 750VDC) and well... current did flow in the right direction but that's all we can say for now.

 

This is one of those things where, if you have to ask, you shouldn't be messing with it. The voltages you're working with are far beyond dangerous.

What is the current output of your array, at the voltage of the battery stack, compared to the charging specification of the batteries?