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TFS-2 or LCS

Posted by: samolangren on

I need to design a DC-DC converter to drive a brush DC motor. The input is regulated 380VDC and the output is 24VDC/15A. Which controller might be better for this application (easy implementation, BOM cost, etc.)?

Comments

Submitted by PI-Wrench on 04/20/2020

The LCS can deliver the power, and an LLC converter will be more efficient in this application than a 2-switch forward using the TFS-2. LLC implementation using large litz wire will be somewhat more problematic than a 2-switch forward transformer, but with the LCS, you don't need an output inductor, unlike the TFS-2 forward design..

Submitted by samolangren on 04/20/2020

Thanks for your recommendations. I have no experience on LLC resonant converter before. Not sure how technically difficult to choose the LC resonant tank. Is the transformer design similar to the regular isolation transformer? Is it available to order an evaluation board with LCS so that I can have a close look on this design?

Submitted by PI-Wrench on 04/21/2020

The PI Expert/PI XLS design suite gives you all you need to optimize an LLC design. An evaluation board is available from Digi-Key (RDK-382). I'm including links to reports for a TFS-2 design and an LCS-based design so you can compare the two approaches. The designs will require some modification to meet your needs.
TFS -
https://ac-dc.power.com/design-support/reference-designs/design-examples/der-484-300-w-forward-power-supply/

LCS -
https://ac-dc.power.com/design-support/reference-designs/design-examples/der-850-240-w-llc-cv-cc-battery-charger-power-supply-using-hiperlcs-an…