UCC28951-Q1: Feedback before the output inductor.

Joseph Francis S

Part Number: UCC28951-Q1
Other Parts Discussed in Thread: UCC28951

In full bridge ZVT converter, can i take the output feedback before the output inductor. If not why.

Then is there any problem will occur when we swap the gate signals of MOSFET A, B by C and D. since there is only series inductor change. I think it wont affect the circuit operation. But one think I need to swap the secondary gate signals. Am I right if not kindly explain. Is there any consequences in the controller.

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,

+1 Mike O' over 2 years ago in reply to Mike O'

TI__Guru* 86286 points

Hello,

You cannot take the feedback before the output inductor using the UCC28951. The control methodology was not designed to work this way.

The output inductor and output capacitor form an LC filter. This filter is used to filter/average a square wave into a usable DC output voltage. This DC output voltage is what you are trying to control.

Regards,

0 Joseph Francis S over 2 years ago in reply to Mike O'

Prodigy 130 points

Thanks for your reply,

Can you also explain the problem when we swap AB and CD mosfet signals

0 Joseph Francis S over 2 years ago in reply to Mike O'

Prodigy 130 points

The LC filter is going to filter the switching frequency only and the feedback it not going to response to the switching frequency, then what is the problem of taking feedback before LC filter

0 Mike O' over 2 years ago in reply to Joseph Francis S

TI__Guru* 86286 points

Hello,

I am reviewing your question 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 this will work. You are trying to control a square wave instead of a DC output voltage.

There is another reason for not doing this. If you don't regulate the output voltage directly you may have regulation issues due to IR drops.

I would not recommend doing this.

Regards,

Power management

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UCC28951-Q1: Feedback before the output inductor.