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Comcokid - thanks, I finally got it as a result of your latest point, so you get a star! What cleared this up for me was you pointing out that it is the duty cycle of the inductor that is important, not the switch. The example circuit was just that: an example. Most of the power semis I see in...

ScottyUK - Yes! The goal is to reduce the ripple in the input capacitor. Now, the question is, will this configuration work? sreid - See above. ;)

I don't know why the two switches can't be in anti-phase, unless your definition of antiphase is 180 degrees of phase shift AND 50% duty cycle for each switch. Attached is a picture of what I am trying to imagine doing. There's no output capacitor because even at a pokey 3kHz switching...

Well, ScottyUK, that's almost the question I am asking... If the switches are paralleled and synchronous then every switch for the previous example is operated at 50% duty cycle. This is easy enough to understand, even for someone that's dead from the neck up, like me. If the switches are in...

Hmmm... I guess I'm not being clear but I don't know how else to phrase the question. Making the example as simple as possible, let's assume the electromagnet needs 170V for 100A and that the dc link is 340V (rectified/filtered 3ph. 240V) and that a buck converter running at an average duty...

Thanks for taking a shot at this, Comcokid. The multiphase buck seems to be very popular for supplying 0.8V at 100A or more to the latest generation of CPUs. The idea is to divide the current among two or more smaller buck converters so that smaller and less expensive components can be used...

That you do, sreid. Not quite what I was asking about, though...

I'm having a tough time visualizing how this might work so I thought I'd pose the idea to the resident geniuses of eng-tips :D Each phase in the typical multiphase buck converter has its own inductor which then feeds a common output capacitor while a single control loop adjusts the duty cycle...

Edit Q2: meant to write, "as the inductor/voltage source in a boost converter".

waross/TurbineGen - Adding a shunt field coil to the series motor/generator will certainly make it behave better, but wouldn't that be cheating?? :o) Anyway, TurbineGen, I am planning on doing just such a test. I have a box of 4 ohm 53W resistors which will make it convenient to increase the...

Aw, crap... I can't believe I missed that, treez... Is there a black star you can give someone for screwing the proverbial pooch, because I sure earned one on that... Yes, D2 (and D3) will conduct heavily if a battery is inserted backwards into this charger. They'll pretty much fry if the...

Hey TurbineGen, thanks for joining in. There may not be much practical application for this thread but my aim was to have some fun and stretch out the few brain cells that are still firing in a non-random fashion. That said, even though I started off wondering about how in the heck a shaded...

I can't seem to find anything out about it either... what is it used in?

Yah, yah, I hear ya.. I need to make better symbols for my EDA software. :) This actually sounds like a really interesting project to try out - seeing if a series dc motor can be made into a reliable generator, that is. Most (all, I think) SMPS topologies present a constant power load to a...

Skogsgurra - that was a quick drawing I did in my EDA software that does not, alas, have a nice symbol in it for a motor, so I cobbled one together out of circle and an inductor. Just try to pretend that's a series motor with the field and armature connected, well, in series. waross - what you...

Excellent explanation of the SR motor/generator behavior, Curt. Now that finally makes sense to me, too. And since the shaded pole motor has been dispensed with, how about your take on my understanding of how a series dc motor can be a generator? Gunnar is not the only one who is skeptical of me...

treez - D2 in the schematic already protects against the battery being connected to the charger backwards (use a Schottky for lower forward voltage drop). Leave in D1 and R3 for an "inserted wrong" indicator if you want but I'd get rid of the 2n7000, q3 and their associated components.

Hey Gunnar... I realize that *practically speaking* a shaded pole motor cannot be used as a generator; I was instead wondering how it *theoretically* could act as one. Also, just to be clear, when I referred to "inductive kickback" in a previous post it was in regards another not-so-suitable...

Talk about an exercise in futility: using an eddy current "motor" as a generator (induction disk kWHr revenue meter)! Still, it sounds like something the over-unity nuts will want to try, doesn't it? (all you have to do is spin a disk of metal in between the windings and it will magically...

Thanks for the replies so far, folks. Note that I am not contemplating actually using a shaded-pole motor as a generator, just trying to understand how it *theoretically* could be used as one! davidbeach - I'm sure there are motors which are not practical to use as generators, but according to...