DC DC bidirectional converter

1

So I have designed this bidirectional dc dc converter to charge and discharge a battery model into a load. The battery model is extracted from the link below:

https://www.plexim.com/support/application-examples/976

However, my model’s performance is incorrect despite adjusting the pi control of the current. In buck mode, the converter doesn’t operate. Can someone point out the mistake, and is there anything else to adjust in terms of the battery model other than the voltage and capacity parameters?

DC DC Current control.plecs (128 KB)

2

Your model is quite convoluted, not sure what the problem is. I don’t think you need two controllers to start with. You can add those if you need different performance for charge / discharge. Also, I would suggest to use MOSFETs in a totem-pole configuration instead of IGBTs.

Your problem can be solved way simpler. See attached minimum working model.

Cheers

Falk

bat.plecs (81.5 KB)

3

Thanks Falk for the reply. I had a look at the model and I have a couple questions in regards to that. Would it be possible if you can briefly explain how the model operates of the model? My concern is that the dc dc bidirectional model is to be connected to a bidirectional ac to dc converter through a dc link. How would such an operation work with this model?

Thanks,

Michel

4

Hi Michel,

The model is a simple synchronous buck converter where I strapped on an I-type controller for low performance current regulation. I would have to guide you to the “Single-Phase Battery Charger” demo model found in the PLECS documentation for grid connected battery systems.

For your research I can suggest the books “Fundamentals of Power Electronics” written by Erickson / Maksimovic and the book “Grid Converters for Photovoltaic and Wind Power Systems”.

Cheers

Falk

5

Yeah I had a look previously at the single phase battery charger; however, it seemed quite complex with different ac dc and dc dc structures than the ones I used. The bidirectional flow wasn’t implemented either. Is your model able to be adjusted to behave as a buck boost converter with constant current and constant voltage modes?

I also included a buck model. I get the correct charging voltage; however, my current is too high (800A) where as my desired one is 20A. Any suggestions in regards to that?

dc dc buck.plecs (113 KB)