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December 03, 2016, 10:48:00 22:48


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Author Topic: PFC and THD Design  (Read 1050 times)
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SANEMB
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« on: December 04, 2012, 05:49:35 05:49 »

I have to make the design for High PFC and Low THD,Please suggest me.how to do calculation.

Right now in my led driver for 18 W output,i got pF around 0.8632 and THD is 18.00

Please i want to reduce thd below 10 and PF>=0.936 please suggest.

Do the needful.
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xenix
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« Reply #1 on: December 04, 2012, 01:30:32 13:30 »

Do you already have a pfc in your led driver? I mean, do you want to increase performance of your pfc or do you want to build a new one?
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SANEMB
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« Reply #2 on: December 04, 2012, 04:07:00 16:07 »

yes ,i have already pfc in driver. now after changing with line filer inductor now i got the pf around the  0.932 but the thd remains same.

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xenix
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« Reply #3 on: December 04, 2012, 04:11:58 16:11 »

Do you have scope and a current probe to capture the line current waveform? If you can share, perhaps we can solve the problem easier.
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enzine
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« Reply #4 on: December 04, 2012, 08:00:42 20:00 »

...i got pF around 0.8632 and THD is 18.00...


How do you measure pF and THD?
In the case of a distorted waveform is not easy to perform these measures properly.

Ciao
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Finzi
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« Reply #5 on: December 04, 2012, 09:45:02 21:45 »

The PFC is directly affected by the level of THD. in general, these kind of drivers present a capacitive load characteristic ( that's why increasing the inductor line's filter increases the PFC. To reduce the THD you'll have to use a second order line filter (L - C) with the cut frequency near and above the line frequency.
But, you might have other ways to improve your drivers performance. Drivers with PFC presents better performance when they operate at +40% of nominal load. If you increase the load I think you'll get better results.
You may try both ideas.
« Last Edit: December 08, 2012, 03:23:50 03:23 by Finzi » Logged
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