Highest power level of Boundary Conduction Mode Boost PFC?

[grizedale]

Hello,

I do Boost Power Factor Corrector with Vout = 385VDC.

V(in) = 90-265VAC.

What is the maximum power that this BCM mode can do.

I need it to provide 220W to its output, is this too much for a BCM boost PFC?

 

[mtwieg]

There's no "limit" inherently with the TCM/BCM operation. As long as your input filter is good enough, you can deal with any amount of ripple in the input current. And if you design the magnetics properly they should be able to deal with the ripple as well.

There's no simple answer to the question. It's just a matter of compromising different parts of the design.

But anyways, 220W doesn't sound like much at all. Do some calculations on that the input ripple current will look like, then take a look at what kind of input filtering is necessary to meet injected ripple specifications. If that filter is acceptable in terms of cost and size, then celebrate.

Oh and also, TI recently came out with some cool interleaved PFC controllers. The UCC28060 and UCC28061 are TCM controllers. The interleaving allows more power to be transmitted while lowering input and output ripple, allowing for smaller filters. They're specified for up to 800W. I used the UCC28070, which is the CCM version, and it works very nicely at 15KW.

 

[grizedale]

With 90VAC mains, the BCM PFC input current peaks up to 9 Amps......surely this is way too much to filter out?

 

[mtwieg]

That depends entirely on what kind of filter you're willing to design and build. And the peak current isn't really relevant; more like the RMS ripple current and frequency spectrum of the ripple.