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UCC28950: UCC28950 for Synchronous rectified PSFB with primary energy storage inductor topology

Miguel GONZALEZ
Prodigy 70 points
Part Number: UCC28950

Hello,


I am designing a railway application battery charger of 1.6kW.

The maximum output voltage is 30V and the maximu current is 54A.

I found in this reference:

Zhao C. , Wu X. , Yao W. , Qian Z. “Synchronous rectified soft-switched phase-shift full-bridge converter with primary energy storage inductor” in Proc. Applied Power Electronics Conference and Exposition 2008 581 - 586

a PSFB topology that could be good  option for my design.

I would like to know if the UCC28950 can be used to control this topology and if you have any experience on it.

I have not found any application note or reference design about it.

Thank you for your help

  • 0
    TI__Intellectual 2910 points
    Hi Miguel,

    Thank you for your interest in UCC28950. I have contacted the applications engineering team for this device so that they can inform you on whether this device can be used in the application you describe or recommend a different product/approach from our portfolio.

    - Daniel
  • 0 in reply to Daniel Ruiz
    TI__Mastermind 25570 points
    Hello Miguel

    I don't have the APEC proceedings to hand but there are some articles published in the IEEE transactions by C Zhao 'Synchronous Rectified Soft-Switched Phase-Shift Full-Bridge Converter with Primary Energy Storage Inductor' which I'll assume describes the same basic idea.

    The short answer is yes - I think that the UCC28950 could be used to control this topology. Basically what Zhao et al are describing is a standard PSFB converter operated in BCM at max load condition or in DCM in all other conditions. The primary energy storage inductor (TI uses the term 'shim inductor') is used to force ZVS at turn-on and turn-off is done at ZCS.
    From the point of view of the UCC28950 the most important thing is that the system is operated at a constant frequency. Among other things this means that BCM is achieved only at a single operating point, DCM of course can be achieved across a wider range of operating points.

    They show a demonstrator at 300W which is only 20% of your intended power level. I think that the usual problems with operating in DCM will emerge at 1.6kW - that is that the peak currents will become too high and give you too much I2R loss. Normally at this power level CCM mode is used to minimise the peak currents - at the expense of higher switching losses of course. On balance CCM is probably a better option at this power level.

    I'd suggest that you evaluate their technique at 1.6KW and look at the conduction losses and switching losses in DCM, BCM and CCM and make a final decision based on what you find. Bear in mind that all of the designs I am aware of at or near to your power level are using the UCC28950 in the 'conventional' (CCM) mode - but please don't let that stop you doing your analysis.

    Please let me know if you need any further help - and my apologies for the delay in getting back to you.

    Regards
    Colin