Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Bill Sloman Newsgroups: sci.electronics.design Subject: Re: power supply idea Date: Tue, 23 Apr 2024 01:09:10 +1000 Organization: A noiseless patient Spider Lines: 34 Message-ID: References: <20240422a@crcomp.net> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Injection-Date: Mon, 22 Apr 2024 17:09:11 +0200 (CEST) Injection-Info: dont-email.me; posting-host="c9cc20431de9dcd31990bf2a191dd6a3"; logging-data="1072464"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1+7BcFJ7LoFZbW0Wf4X4o+urWp6ZLiout8=" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:IPpVK17aFYPpxZChuRn5ki2Po24= Content-Language: en-US In-Reply-To: <20240422a@crcomp.net> Bytes: 2406 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. -- Bill Sloman, Sydney