UCC28950: I have to deseing a step up/ boost converter using this controller

Zain ur Rehman

Part Number: UCC28950

Tool/software:

I am to start working on a dc dc converter, following are my requirements.

Vin; 26V, Range:20-32V

Vout: 60V, 25A, 1500W, Isolated, conduction cooling, fan-less design

Question is if it's possible to achieve a high eff psfb design given my specifications. I haven't found any ref design or paper close to what I want. Webbench generated a very non practical schematic which is not possible for e.g. 300mF input capacitance. The main issue however is leakage inductance, even SLUC222 tell me to have a Lk of -4uH. So, I am want to know what approach to design should I follow?

4 months ago

0 Ning Tan 4 months ago

TI__Genius 12795 points

Hello,

We will get back to you by tomorrow.

0 Zain ur Rehman 4 months ago in reply to Ning Tan

Prodigy 70 points

Sure

0 Mike O' 4 months ago in reply to Zain ur Rehman

TI__Guru* 86126 points

Hello,

The following link will bring you to an application note that goes through the step by step design process of a phase shifted full bridge using the UCC28950. Inside there is a link to an excel design tool that uses the same calculations as the application note. You should be able to use these tools to design a converter that is 90 to 95% efficient for your application.

https://www.ti.com/lit/pdf/slua560

Regards,

0 Zain ur Rehman 4 months ago in reply to Mike O'

Prodigy 70 points

I talked about the excel tool sluc222 and told you it gives me leakage of -4uH. A non-practical value for my design.

0 Mike O' 4 months ago in reply to Zain ur Rehman

TI__Guru* 86126 points

Hello,

If the tool gives you a shim inductance of a negative value that means your design does not need a shim inductance to achieve ZVS down to 50 % load. I would leave a place holder for one anyway just in case you want to experiment.

Regards,

0 Zain ur Rehman 4 months ago in reply to Mike O'

Prodigy 70 points

Yes but that greatly reduces the efficiency of the system. As leakage inductance will responsible for power loss.

0 Mike O' 4 months ago in reply to Zain ur Rehman

TI__Guru* 86126 points

Hello,

The device uses the energy in the leakage inductance and shim inductor to achieve ZVS. The energy is recycled and will not be dissipated.

Regards,

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UCC28950: I have to deseing a step up/ boost converter using this controller