Electronics > Power/Renewable Energy/EV's

Ripple current rating of Film capacitor in Half Bridge SMPS?

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The attached (LTspice sim and PDF schem) is a 3.6kW Half Bridge SMPS. 3 Phase 240VAC input. 3 phase , 6 pulse rectifier, 12V, 300A output.
The Half Bridge primary side rail splitter caps each have 26Arms of ripple current in them.

They are as follows…
Film capacitor: 12uF MAB MKP 12/400 Siemens

Here is a picture of it on ebay...

A proper datasheet cannot be found. (also they dont weigh anything like 1Kg) Do you know how much ripple current they are rated for?

How did I guess that this would come round to your 3.6kW half bridge?  ::)

As I explained in your other thread yesterday... https://www.eevblog.com/forum/beginners/what-is-the-ripple-current-rating-of-this-film-capacitor/ , those are bog standard motor run capacitors - they don't specify the figures that you want, specifically, they are rated for 50/60Hz, not 20kHz. Why bother wasting peoples' time if you don't care about the answer!

If a figure isn't specified, you can't make use of it. You are asking them to operate at about 20 times the current that they would expect to see!

Please stop being treez.


Special low ESR high current term film caps are need for high freq high ripple current bridge service.

You CANNOT use a 50/60 Hz PFC or motor start cap! Thy will fail.
These are not cheap nor readily avail.

We used to parallel a bunch of the stacked foil WIMA caps for protos
The US old line cap mfg used to make them, Sangamo, AreoVox, Cornell-Dublier.

Am sure the Chinese have cloned these designs.

Can send a few photo's if I dig some out of my junkbox.....

Kind Regards,



--- Quote from: mag_therm on January 17, 2022, 08:51:55 pm ---For hobby low power homebrew inverters like this, I would recommend to try to find some snubber capacitors from industrial sized inverters.

--- End quote ---

As a relative newcomer around here you may be unaware of the 'treez' phenomenon and thus may be misleading yourself. Farringdon (who has been known by a number of user names over the years) often comes looking for free advice for his day job, which is the commercial design and production of power supplies. So there is every possibility that we're not looking, appearances aside, at a hobby project here.

Thank you,
I removed all my posts on the subject.


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