Anybody here familiar with some of the stability quirks and
parasitic issues with this type of design?
I believe I'm having a damping problem with the passive power
parts.
I'd like to SPICE the loops but I don't know how to linearize
for phase/gain plotting. Know any sources?
If you have a semi working model, you can measure the gain and
phase of
the system. You normally start by making the servo control loop
way slow.
You can then inject a small signal and measure its effect.
Exactly how you are doing the hysteresis controlled version of
the
converter may make this hard to do. You may have to first
figure out
what the expected ripple on the output is and replace that with
a
generator injected into the comparitor.
Making a Cuk stable can be extra tricky because there are two
complex pole
pairs, a couple of zeros and some extra phase shift at the high
end that
doesn't have a gain decrease to go with it.
Stability may be over rated. A "hit and miss" regulator can
never be
truly stable but they perform quite well. A nice stable
waveform looks
good on a scope but makes it harder to pass the FCC. Adding
noise to the
switching frequency spreads the RF out and lowers the peaks.
Details
Hysteresis controlled
Offline
Output 100VDC@2Amps
Input 120VAC
Thanks
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[email protected] forging knowledge
..
Hello Kensmith
Thats for the info..
It's that classic cuk config that I'm stuck on.
Stability analysis with amplifiers..is easy...A bode plot is
in&out sin wave frequency, amplitude and phase at an operating
point.
But with switchers...It's like 2 operating points and then
there's a duty factor too.
I've heard that the cuk can be transformed for spice to get a
bode plot..
Some sort of averaging theory to linearize the circuit for spice
simulation. The switch and diode are replaced with linear
"boxes".
I wonder if I have to do this for the hysteresis controlled cuk?
|-R-C----|
------L------|---C----|------L---|
D A |
pulses in>>---Mosfet diode load
S C |
| | |>>triangle I ....Bode Plot??
Gnd Gnd Gnd
