Re: power supply idea

On Mon, 22 Apr 2024 16:32:00 +0100, John R Walliker
<jrwalliker@gmail.com> wrote:

On 22/04/2024 16:09, Bill Sloman wrote:

On 22/04/2024 10:57 pm, Don wrote:

John Larkin wrote:

>
If one had, say, a 48 volt power bus, you could hang a half-bridge
switcher to ground, and a lowpass filter out. If the drive has duty
cycle n, the output voltage is 48*n. So we have a programmable power
supply with no feedback, which will be stable into any load.
>
The load regulation will be mediocre, but we could almost sell it
as-is.
>
So now, sense the output voltage and compute the error against the
target, run through a slowish integrator, and tweak the PWM to get
zero output voltage error. Gross transient response is basically the
response of the output filter, with some modest drool from the
integrator.
>
We can constrain the influence range of the integrator, just enough to
give the regulation that we need. That limits output swing in case the
feedback is wrong, as one could get from a botched remote sense
connection.
>
https://www.dropbox.com/scl/fi/2fysyvkl4eim7vujhaobh/FFINT_PS_1.jpg?rlkey=rug6yi3cgemi9vvbz8apgboqi&raw=1

>
Is your "spread spectrum" dodad supposed to mitigate EMI?

 
It smears it out over a range of frequencies, and makes it look better
on the screen - no big frequency spikes, but many more smaller ones.
 
"Mitigate" depends on how the hash messes up your particular system.
 

>
Yes, but the only one that most designers care about is the EMC
receiver at the compliance test lab.
>
John

It won't reduce ripple or fast switching spikes, which is what my
users might care about. It would improve the peaks on a spectum
analyzer, which is what regulators (government regulators, not voltage
regulators) care about.

Actually, the DC power that one sees on an airplane or in a car is
nastier than anything I can reasonably make, even on purpose. So my
concern is stability and not blowing anything up.