I'm not looking for very detailed explanation (although it would be welcome). I'm more looking to intuitively understand how it works.
Basically in computer PSU I have input followed by filters followed by PFC circuit followed by switch followed by transformer followed by rectified and in the end I have output filtering and consumer. From what I've read the same PWM circuit which controls the switch and regulates voltage at the output also controls the active power factor correction.
What I don't get is the way the power factor is actually corrected.
Here's a picture:
How do those two transistors work here and how would the PFC controller determine that the power factor is bad?
I know that the power factor is usually corrected with coils and capacitors and I see both here, but I don't understand what actually happens when one of the transistors starts to conduct, why two transistors are needed and how that affects the power factor.