Path: ...!Xl.tags.giganews.com!local-2.nntp.ord.giganews.com!nntp.supernews.com!news.supernews.com.POSTED!not-for-mail NNTP-Posting-Date: Mon, 22 Apr 2024 16:06:09 +0000 From: John Larkin Newsgroups: sci.electronics.design Subject: Re: power supply idea Date: Mon, 22 Apr 2024 09:04:21 -0700 Organization: Highland Tech Reply-To: xx@yy.com Message-ID: References: <20240422a@crcomp.net> X-Newsreader: Forte Agent 3.1/32.783 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Lines: 53 X-Trace: sv3-XMJyXWf04VG2Y/0Tz4vlTTvw0iPChqD650b9r2BFHHTEAr8nZ2R3J4FJ4hwGfxDdmbv+sxrS6C4hLZY!kGK7qSQLlFMgCqN824ur4P/UPevpz3TP5i33SFBcLP33XF1Yvyk5XLqxRVhtJgN84soqyqvXDq6T!fg5GgA== X-Complaints-To: www.supernews.com/docs/abuse.html X-DMCA-Complaints-To: www.supernews.com/docs/dmca.html X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly X-Postfilter: 1.3.40 Bytes: 3288 On Mon, 22 Apr 2024 16:32:00 +0100, John R Walliker 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.