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Mains harmonic currents into SMPS are too large?

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grizedale

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Hello,

I have designed a 330W SMPS which runs off 90VAC via a voltage doubler. (it has no PFC because its for audio)

I have done an equivalent simulation so as to calculate the mains harmonic currents.

I am getting 5.73 Amps at the third harmonic current level....how can this be?


PAGE 8 SHOWS input current harmonic limits.............
**broken link removed**


Here is my mains input current:-
http://i51.tinypic.com/13zwcv6.jpg

......it is 3.5 Amps RMS

Here is the FFT of the above mains input current:-
http://i55.tinypic.com/33ju8v5.jpg


...the third harmonic is shown to be 4.31dB which represents 5.73 Amps RMS

calculation = 20log([3rd harm]/3.5) = 4.31dB
...then work out "3rd harm" from this, it comes out as 5.73 Amps

here is the LTSpice simulation schematic....which is just a "token" SMPS which draws 110W constant power.
http://i51.tinypic.com/11l0nx0.jpg


-So howcome i have this huge 3rd harmonic current? , which would fail me on the approvals testing
 
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