Path: ...!2.eu.feeder.erje.net!feeder.erje.net!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: John R Walliker <jrwalliker@gmail.com>
Newsgroups: sci.electronics.design
Subject: Re: power supply idea
Date: Mon, 22 Apr 2024 16:32:00 +0100
Organization: A noiseless patient Spider
Lines: 38
Message-ID: <v05vr8$qc8s$1@dont-email.me>
References: <q42b2jlb2r37otmia4acdbgkdjb9r1aovn@4ax.com>
 <20240422a@crcomp.net> <v05uim$10nag$2@dont-email.me>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Injection-Date: Mon, 22 Apr 2024 17:30:49 +0200 (CEST)
Injection-Info: dont-email.me; posting-host="06340866ad211c76e38de90fd553948e";
	logging-data="864540"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX18kYKJ1KlonqMgKO9iiWAv+Wpds0BqqDOw="
User-Agent: Mozilla Thunderbird
Cancel-Lock: sha1:I1vuyW8visFZZYNQv5Xz0VDrfyw=
Content-Language: en-GB
In-Reply-To: <v05uim$10nag$2@dont-email.me>
Bytes: 2649

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