Hi
I am working on a LLC converter like this:
Normally it?s running at 50% duty cycle with frequency control loop
I am just wondering what happens if I ramp up the duty cycle from 0 to 50%?
Won?t that ease up on the inrush current? Assumption is that I can target the resonant point
Cheers
Klaus
Of course, The harmonics won?t be odd any more, but should not matt er much since anything above 2 Fres will be attenuated, although the conten ts of the reactive current will be larger
Cheers
Klaus
It should work although the common method for LLC soft-start is to start at a high frequency (where the voltage gain of the whole converter is very low) and then let the frequency gradually drop down until the loop kicks in and begins regulating the frequency.
These guys are proposing both, frequency as well as duty-cycle control:
-- Regards, Joerg http://www.analogconsultants.com/
Thanks Joerg ?
Good article reference and exactly what was looking for
Cheers
Klaus
On Saturday, September 23, 2017 at 5:47:11 AM UTC+10, Klaus Kragelund wrote :
op
%?
n target the resonant point
Looks like the serial form of the Baxandall class-D converter.
-- Bill Sloman, Sydney
On Saturday, September 23, 2017 at 4:09:01 AM UTC+2, snipped-for-privacy@ieee.org wrot e:
te:
loop
50%?can target the resonant point
o work out how to inject the extra current to replace the quadrature curren t you would have got from the extra capacitance or inductance that would ha ve made the tank resonant at the frequency that you want - but it can be do ne.
It is possible to linearize the resonant converter with a trick, so feedbac k control gets a lot easier. Depends on what control IC is used
Can you elaborate on the replacement of quadrature current?
Cheers
Klaus
On Saturday, September 23, 2017 at 8:29:58 PM UTC+10, Klaus Kragelund wrote :
ote:
rote:
l loop
o 50%?
I can target the resonant point
to work out how to inject the extra current to replace the quadrature curr ent you would have got from the extra capacitance or inductance that would have made the tank resonant at the frequency that you want - but it can be done.
ack control gets a lot easier. Depends on what control IC is used
Not in any useful way, in this kind of forum. Send me an e-mail if you have a specific idea in mind.
-- Bill Sloman, Sydney
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