UCC28070: THD optimization

Lin Zhao

Part Number: UCC28070

Hi,

My customer adopt UCC28070 to 1.6KW power, need 5% THD, according our EVM user guide, the THD seems can't meet customer's request.

Any suggestion on how to optimize THD? could 28070 achieve 5% THD?

thanks.

over 7 years ago

0 John Griffin1 over 7 years ago

TI__Mastermind 34465 points

Hello Leo,

Yes it is possible to achieve 5%THD with the UCC28070.

You can minimise the THD by optimizing the loop characteristics of the converter, minimizing the amount of input capacitance, maximizing the amount of boost capacitance and by minimizing the amount of bias compensation that is used with the CSA,CSB signals.
Please utilize the Excel design calculator for the UCC28070 and review your circuit design and pcb layout.
You will no doubt find that the THD can be improved.

Regards

John

0 Peiyong Li over 7 years ago in reply to John Griffin1

Prodigy 100 points

Could you show us the THD data and parameters with THD optimized of TI EVM in vary load and input voltage? Thanks.

0 John Griffin1 over 7 years ago in reply to Peiyong Li

TI__Mastermind 34465 points

Hello Leo Zhao,
The EVM was designed to demonstrate to the capabilities of the UCC28070 and it was never optimized for harmonic performance.
The information you are looking for is not readily available.
Regards
John

0 Lin Zhao over 7 years ago in reply to John Griffin1

TI__Intellectual 1230 points

Hi John,

Got to know that PR779 have THD optimization and THD could reach <5% at full load, could you pls share us the detailed test report for this design? it's not able to achieve on TI.com. thanks.

http://www.ti.com/tool/PR779

0 John Griffin1 over 7 years ago in reply to Lin Zhao

TI__Mastermind 34465 points

Hi Leo,
I have been unable to locate a test report for this design. Sorry about that.
All I can suggest is that you follow the suggestions of the UCC28070 calculator and adjust the amount of bias and offset on the CSA,CSB signals as required. I notice that the PR779 does not use any compensation on the current sense signals.
Regards
John

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UCC28070: THD optimization