UCC27714EVM-551: Using TI evaluation module for constant power control operation.

Gaureej Gauttam

Part Number: UCC27714EVM-551
Other Parts Discussed in Thread: UCC28950, , PMP8740

I want to use UCC27714EVM-551 TI evaluation module as a constant power controlled Phase Shifted Full Bridge (PSFB), using the UCC28950 controller card provided with it.

I want suggestions on how to use the this evaluation module for the same as per following requirement:

Vout = 20-30V
Case 1) Pout = 300W (constant & controlled using the UCC28950 controller card provided)
Case 2) Pout = 100W (constant & controlled using the UCC28950 controller card provided)
This output will be fed to another converter which is supplying a pulsed load.

My aim is to use this evaluation module to work in Average Current mode control to process constant power at any instant with an output voltage which can be allowed to vary around 20-30V as per the load variation.

Can you suggest me how should I use/modify the controller for this operation?

Thanks,

Gaureej

over 2 years ago

0 Mike O' over 2 years ago

TI__Guru* 86286 points

Hello,

I am reviewing your inquiry and will get back to you shortly.

Regards,

0 Mike O' over 2 years ago in reply to Mike O'

TI__Guru* 86286 points

Hello,

I don't think, I would use average current mode control. To prevent transformer saturation you would need a DC blocking capacitor in front of the transformer.

A better approach would be to do a constant current/constant voltage design to control the output current and output voltage. The following link will bring you to a 2 kW battery charger reference design that uses this approach.

https://www.ti.com/tool/PMP8740

The following link will describe how to design buck style regulators for constant current/constant voltage. The same technique should work with the phase shifted full bridge and is a similar approach that the PMP8740 used.

https://www.ti.com/lit/an/snva829/snva829.pdf?ts=1687897186577&ref_url=https%253A%252F%252Fwww.google.com%252F

Regards,

Mike

0 Gaureej Gauttam over 2 years ago in reply to Mike O'

Prodigy 55 points

Thanks Mike,

I want to implement Average current mode control on this. Is it possible to implement using this evaluation board? Can I add DC blocking capacitor externally?

Regards,

Gaureej

0 Mike O' over 2 years ago in reply to Gaureej Gauttam

TI__Guru* 86286 points

Hello,

You will just need to add the DC blocking capacitor in series with the HBridge transformer.

The control card is setup for peak current mode and not average mode control. You could use the card for for voltage mode control. However, you are correct that it is not setup for average current mode control.

Regards,

0 Gaureej Gauttam over 2 years ago in reply to Mike O'

Prodigy 55 points

Hi,

In the datasheet of the controller card UCC28950_controller it is stated that it can be used for both peak or average current mode control. I think that after adding the DC blocking capacitor. I can make changes in the controller card so as to use it for average current mode control. Could you please confirm this?
And if possible for you, could you also share the changes that I need to make for using it as an average current mode controller?

Thanks & regards,
Gaureej

0 Mike O' over 2 years ago in reply to Gaureej Gauttam

TI__Guru* 86286 points

Hello,

The EVM was not designed for average current mode control. However, you can modify the EVM for average current mode control.

The Constant Current/Constant Voltage mode control is actually a form of average current mode control. The output is controlled with and additional feedback path. Also to control the output power will be easier with a constant output voltage. Pout = Iout*Vout.

To implement the constant current/constant voltage design can be done based on PMP8740 and snva829.

https://www.ti.com/tool/PMP8740

https://www.ti.com/lit/an/snva829/snva829.pdf?ts=1687897186577&ref_url=https%253A%252F%252Fwww.google.com%252F

Regards,

0 Gaureej Gauttam over 2 years ago in reply to Mike O'

Prodigy 55 points

Thanks.

I'll try the modification or output power control using CC/CV control. And will get back to you if I need any additional help.

Thanks,

Gaureej

0 Mike O' over 2 years ago in reply to Gaureej Gauttam

TI__Guru* 86286 points

Hello,

Thanks for letting me know.

Regards,

0 Gaureej Gauttam over 2 years ago in reply to Mike O'

Prodigy 55 points

Hello,

I want your suggestion on where can I include the DC blocking capacitor in the board as I did not find any place available in the evaluation board PCB?
Also, the reason I want to go with average current mode control not the CC/CV control is that I have a pulsed load and I want the PSFB to process only the average power. If I would use CC/CV it would process peak power.

Regards,
Gaureej

0 Mike O' over 2 years ago in reply to Gaureej Gauttam

TI__Guru* 86286 points

Hello,

I am reviewing your inquiry and will get back to you shortly.

Regards,

0 Mike O' over 2 years ago in reply to Mike O'

TI__Guru* 86286 points

Hello,

Please see my comments below.

I want your suggestion on where can I include the DC blocking capacitor in the board as I did not find any place available in the evaluation board PCB?

>The need of this DC blocking capacitance is why many designers choose to do peak current mode designs.

>You try to modify the board and air wire it in. However, that adds stray inductance and capacitance to the layout. It might be a better option to lay out a new board with room for the DC blocking capacitor.

Also, the reason I want to go with average current mode control not the CC/CV control is that I have a pulsed load and I want the PSFB to process only the average power. If I would use CC/CV it would process peak power.

> If you use CC/CV you would be controlling the DC output current with an amplifier. You would be controlling the peak current on the primary as well with this technique.

Regards,

Power management

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UCC27714EVM-551: Using TI evaluation module for constant power control operation.