TIDM-02013: CLLC output capacitance, active EMI filter

wout vanderwegen

Part Number: TIDM-02013

Tool/software:

Hi,

I have 2 questions regarding the 7.4kw OBC.

1. Do you have a calculation or documentation on how the output capacitors of the CLLC stage are sized? 600µF seems very large. When I do the simulation, 2µF to 10 µF can suffice.

2. We noticed that there is an active EMI filter included in the schematic. Is there some documentation/implementation about this part? My team is interested in trying/ testing this feature.

Kind regards,

Wout

9 months ago

0 Darwin Fernandez 9 months ago

TI__Mastermind 41800 points

Hi Wout,

1. The output cap selected based on the ripple current. It can very well be lower as long as you selected the capacitor that can support the RMS current.

2. For active EMI filters, I recommend looking at the devices below.

https://www.ti.com/power-management/power-supply-filter/overview.html

0 wout vanderwegen 9 months ago in reply to Darwin Fernandez

Prodigy 20 points

Hi Darwin,

Thanks for your answer, but could you elaborate more on the ripple current calculation? When I calculated the RMS current, it looks like the 2 ceramic capacitors used (B58031I5105M062, Irms=11A) were already enough. Also, the 2 ceramic capacitors can handle twice the RMS current compared to the 2 electrolytic capacitors (ALA8DA301CF500, Irms=4.8A), so why still use the electrolytic capacitors?

0 Darwin Fernandez 9 months ago in reply to wout vanderwegen

TI__Mastermind 41800 points

Hi Wout, the discrepancy could very well be simulation related. I recommend you design similar to what was designed on the reference design since it is a proven working solution. Or you leave footprint to have similar output capacitance to the reference design so that if needed, it can be populated.

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TIDM-02013: CLLC output capacitance, active EMI filter