About charging voltage control for battery

Kandyman

Dear Wolfspeed,

I have a question about how to adjust the charging voltage in battery charging mode.

The explanation in the document explains that the gain (battery voltage) is adjusted by PFM-PS in CLLC. Is it correct? 

In the case of CLLC PFM-PS control, I know that it has a very narrow gain range. so, is it possible to control the battery charging voltage(200-800Vdc) only with the CLLC PFM-PS controller while maintaining effective efficiency in the AC/DC DC fixed voltage state?

I wonder how to control the wide battery charging voltage.

TBhatia

Hello Kandyman, thank you for your message. A member of our technical team is looking into your questions and we will respond shortly. 

In the meantime, can you provide the document you're referring to?

Kandyman

Dear TBhatia,

I refered to the document below.

• CRD-22AD12N : Design Challenges and Considerations of Wolfspeed 22kW High Efficiency Bi-directional ACDC Converter Jan 2021.pdf
• CRD-22DD12N : Wolfspeed 22kW High Efficiency Bi-directional DCDC Converter online Oct.pdf

However, the question is asked because there is no clear explanation of where and how to control the wide voltage range in the above document.

The purpose of the question is how to control the battery charging voltage. For example, controlling battery charging voltage with DC/DC gain control in AC/DC fixed output voltage state? Or is it AC/DC voltage and DC/DC gain control at the same time... I'd like to know about that.

Best Regards,

minook

FrankWei

Hello Kandyman,

if you fix the DC output voltage of the PFC stage, and a constant output power is required for 200-800Vdc output, it is not easy to have it with the CLLC by PFM-PS control. you can consider to have configurable output connections from two converters. what do you think? thanks.

Regards,

Frank

Kandyman

It is known that the CLLC resonant type is not efficient at low voltage levels in a wide range

such as 200 ~ 800Vdc due to narrow voltage gain.

So, I want to know about some approach direction.

Please give me some hints. ^^

FrankWei

Hi Kandyman,

Yes. you are right. It is known that the CLLC resonant type is not efficient at low voltage levels in a wide range. normally, two converters is required to get the 200-800V output. for 200-400, two outputs are in parallel. for 400-800, two outputs are in serials. In this design, it is special. we reconfigured the full bridge CLLC into a half bridge CLLC for low voltage output. the gain can be reduced to 50% naturally. you may contact Wolfspeed sales team. if Wolfspeed component is in your bom, with an agreement, it is OK to leverage the IP. thank you.

Regards,

Frank

TBhatia

Hi, I hope that this answered your question. I will close this discussion for now but if you have a follow up question, please "Start a New Discussion" and we would be glad to support you further.