900 W PFC Stage Using HiperPFSTM

Posted by: harrison on 08/03/2011

Hello,
in the design report of 900 W PFC Stage Using HiperPFSTM
PFS729EG,the inductance of LPFC at full load is 237uH and 2370uH at no load.

Question No.1:
so is 237uH the calculated value at full load?
what is the percentage of ripple current?

Question No.2
while I don't see a problem with higher indctance at lower load, but this is 10:1 ratio of zero-inductance against full load inductance, is n't it too big?
I usually use 2:1.
are there any problems associated with higher inductance?

Thank you

Comments

The core used is 125u type Sendust so inductor will "swing" considerably. This is actually desirable because the converter will tend to be in continuous conduction mode over a wider load range as compared with a more linear inductor. Power factor is better when converter is operating substantially continuous over the AC input envelope.

Hello,

Thank you very much for your reply.
please have a look at the table on page 16, Inductor construction parameters, it says the core loss is only 2.07w.

I checked the specifications of the core and I got much higher core loss than it is in the table.Can you please doublr check if this 2.07w is correct?

thank you,

Thank you very much for the reply.
while reading the whole note for this PFC, the last part is about winding the toroid;
for the second ayer winding(the same for third layer), why not winding the same direction as the first layer?

the way of this winding , the second layer is counter-clockwise while the third layer is clockwise, would they cancel each other?
why it has to be split into two halves to wind this inductor?

Thank you very much