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I've done polyphase bucks, but not boost. Might be useful.
john larkin <jl@glen--canyon.com> wrote:
I've done polyphase bucks, but not boost. Might be useful.
Hmm. Polyphase is most useful at highish power levels, which is not what
IAd instantly associate with a boost converter.
The boost topology has that nasty unstable zero at higher loads. You know: >regulator goes into CCM, power demand goes up, duty cycle increases. The >power is delivered after the switch opens, so that increases the response >delay, increasing the sag, the controller overreacts,a i.e. the behavior
that slope compensation is intended to fix.
Figuring out how to do slope compensation in a polyphase converter might be
a challenge.
Cheers
Phil Hobbs
(Whose switcher designs to date are all below 20 watts)
On Wed, 13 Aug 2025 22:54:44 -0000 (UTC), Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
john larkin <jl@glen--canyon.com> wrote:
I've done polyphase bucks, but not boost. Might be useful.
Hmm. Polyphase is most useful at highish power levels, which is not what
I-Ad instantly associate with a boost converter.
The boost topology has that nasty unstable zero at higher loads. You know: >> regulator goes into CCM, power demand goes up, duty cycle increases. The
power is delivered after the switch opens, so that increases the response
delay, increasing the sag, the controller overreacts,-a i.e. the behavior
that slope compensation is intended to fix.
Figuring out how to do slope compensation in a polyphase converter might be >> a challenge.
Cheers
Phil Hobbs
(Whose switcher designs to date are all below 20 watts)
The advantage is that one might use a few small fets and inductors. I designed an 80 amp three-phase buck regulator once because a
single-phase version was burning the paint off my inductors.
john larkin <jl@glen--canyon.com> wrote:
On Wed, 13 Aug 2025 22:54:44 -0000 (UTC), Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
john larkin <jl@glen--canyon.com> wrote:
I've done polyphase bucks, but not boost. Might be useful.
Hmm. Polyphase is most useful at highish power levels, which is not what >>> I?d instantly associate with a boost converter.
The boost topology has that nasty unstable zero at higher loads. You know: >>> regulator goes into CCM, power demand goes up, duty cycle increases. The >>> power is delivered after the switch opens, so that increases the response >>> delay, increasing the sag, the controller overreacts,? i.e. the behavior >>> that slope compensation is intended to fix.
Figuring out how to do slope compensation in a polyphase converter might be >>> a challenge.
Cheers
Phil Hobbs
(Whose switcher designs to date are all below 20 watts)
The advantage is that one might use a few small fets and inductors. I
designed an 80 amp three-phase buck regulator once because a
single-phase version was burning the paint off my inductors.
Fair enough, if you can make the slope compensation work. Of course,
assuming the load regulation is adequate, you could also make the loop slow >enough that it doesnAt matter.
Cheers
Phil Hobbs
On Thu, 14 Aug 2025 11:33:00 -0000 (UTC), Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
john larkin <jl@glen--canyon.com> wrote:
On Wed, 13 Aug 2025 22:54:44 -0000 (UTC), Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
john larkin <jl@glen--canyon.com> wrote:
I've done polyphase bucks, but not boost. Might be useful.
Hmm. Polyphase is most useful at highish power levels, which is not what >>>> I?d instantly associate with a boost converter.
The boost topology has that nasty unstable zero at higher loads. You know:
regulator goes into CCM, power demand goes up, duty cycle increases. The >>>> power is delivered after the switch opens, so that increases the response >>>> delay, increasing the sag, the controller overreacts,? i.e. the behavior >>>> that slope compensation is intended to fix.
Figuring out how to do slope compensation in a polyphase converter might be
a challenge.
Cheers
Phil Hobbs
(Whose switcher designs to date are all below 20 watts)
The advantage is that one might use a few small fets and inductors. I
designed an 80 amp three-phase buck regulator once because a
single-phase version was burning the paint off my inductors.
Fair enough, if you can make the slope compensation work. Of course,
assuming the load regulation is adequate, you could also make the loop slow >> enough that it doesnrCOt matter.
Cheers
Phil Hobbs
We might have an FPGA in the loop, so we can do tricky things. Most everything seems to have an FPGA lately.