Hello,
We are designing a 3kW LLC converter (battery charger) with Vin=425VDC, and Vout = 400vdc, 3kW. (schematic below)
Please give your opinion on the core losses in the PQ3535 ferrite core that we are using as the LLC converter transformer?
(It uses ferroxcube 3C95 ferrite and is centre leg gapped for an AL value of 1000nH/N^2
The circuit is as below. (LTSpice schematic also attached)
In order to get up to 400vdc at the output the switching frequency has to go as low as 80khz.
This gives a peak B of 390mT (but this is considering the “AMIN” value of core area)
Considering the “AE” value of core area, the peak B is 333mT.
Considering the peak B of 390mT, this gives core losses of 16.3 Watts
Considering the peak B of 333mT, this gives core losses of 13.1 Watts.
The above core losses are derived from page 95 of the Ferroxcube “soft ferrites and accessories data handbook 2013”..
https://www.ferroxcube.com/FerroxcubeCorporateReception/datasheet/FXC_HB2013.pdf
Which core area value should we abide by, and are these core loss levels manageable if we mount the core by gap-padding it to the metal enclosure?
(I have always abided by “AMIN” in the past, but for this product we are extremely space constrained.)
The PQ3535 core details are on page 742 of the linked ferroxcube databook.