3uF Film cap hides mains harmonics fail?

[cupoftea]

Hi,
Just Tested a 150W Single Stage PFC'd SMPS for mains harmonics.
It passed over 100-265VAC.
However, i suspect that the pass was by way of the high value film capacitors in use in the primary side.
The AC filter consists of nothing more than a 3uF film cap at the front end, and then a 47uH inductor of 2A rating

47uH indcutor

https://www.we-online.com/components/products/datasheet/7447720470.pdf.

...Then downstream of the mains bridge , there is a 5u6 film cap.

Do you think these high value film caps could be masking an otherwise Mains Harmonics fail?

(just asking, will try a sim myself , but unsure whether EN61000-3-2 uses Blackman windowing or whatever for the FFT)

 

[cupoftea]

Actually, the FFT of a 150W PFC sim shows that a 3uF cap at the front end very very slightly improves Mains Harmonics......adding capacitance downstream of that, ie, downstream of the filter inductors, makes the harmonics worse. At 150W, its amazing how badly distorted the mains input current waveform can be and yet it still complys with class A Mains Harmonics.

 

[Easy peasy]

Class A - yes

 

[Easy peasy]

That's a lot of C for an 150W psu - the power factor must be quite leading ....

 

[cupoftea]

Thanks Yes, from the LTspice sim used, the PF was <0.8...with the 3uF X2 cap and the 5u6 post bridge cap.