Matching to the impedance of an alternator.

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Annoy me by showing how my description of alternator behavior, the solution to your "puzzle", is wrong. Hell, annoy me by saying anything intelligent about alternators.

I've probably designed about 1600 different circuit boards, sold maybe $250e6 worth of gear I designed, created maybe 5000 person-years of jobs, and I have one patent.

I do have the rights to use the patent.

John

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I suspect that due to the inductance of the source impedance, it would be a good idea to pull sinusoidal current (PFC front end). Adding series capacitance to the converter would also help in being able to pull more current from the dynamo. Being able to tune that capacitance as load and dynamo speed change could be nice.

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Conjugate matching is interesting, but if you null out the inductance, current will be limited only by copper loss, and you *could* fry the windings. Besides, that would be hard to do over a frequency range.

We'll wait for Jim's solution to the problem.

John

voltage.

Yes, of course. I meant to say that the voltage and frequency track. Both increase with shaft speed.

John

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I didn't peep, I just observed that it was happening. I never joined a frat.

And I seem to recall that it was you who was pontificating about non-conservation last year... thus my laughter.

Oh, yes, before I forget... kiss my ass. ...Jim Thompson

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Doesn't it trouble you to be using chips I designed? ...Jim Thompson

Weeks ago

Not really.

Speak for yourself.

Remember: "its not what you know - its who you know", he probably had a troupe of interns he could send off on assignments while he claimed the credit.

Bear in mind its only a bicycle lighting set we're talking about here - not Jodrel Bank!

The original objective is to down convert the voltage so the current draw is less - which allows the voltage to rise in the first place.

If the balance is right, this aproximates to matching the load for the maximum Po that the dynamo (alternator) can provide.

The dynamo I'm experimenting with came into existence about 1910 or shortly thereafter - in the absence of solid state switching regulators; the designer resorted to regulating the output by shunting it with a pair of 6V bulbs that added up to 0.3A in the hope they wouldn't blow if you pedalled faster.

I believe the alternator Po will "flourish" if the voltage is allowed to "stretch its legs" so to speak, but I still want to end up with a voltage appropriate for charging a 3-cell SLA battery - hence the step down with a buck regulator.

A three-phase PM synchronous motor sure as hell will...

"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

AKA: A troupe of interns sent off on assignments.

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Why would I care who designed a chip if it works? I doubt that you get any revenue when I use a 12 cent part that you designed some of, for hire, a zillion years ago; whereas I get a lot of revenue, every time. I wouldn't much care if I drove on a road that you helped pave, either.

You sure have weird ideas about what matters.

I'm thinking that you actually know very little about electronics, or physics, or optics, or electromagnetecs, or thermo, because you never say anything sensible about them. I think people figure out what they want done, and hire you as sort of a high-tech wallpaperer, to put the transistors down.

So, say something intelligent about alternators.

John

That would be a lot of very big nonpolarized caps and a lot of high-current, high-voltage switches. And if you do it really well, you can fry the alternator windings.

Cool, post a schamatic.

John

OK, but keep in mind the thing about free lunches. As you match the impedance better, the alternator will deliver more power, and you'll have to pedal harder. OK on downhills, as recovered dynamic braking.

John

Its only a 1.8W alternator and I'm not expecting that big a 'free lunch' - just a little extra going into the SLA to cover occasional use of a 3W Cree.

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So go for partial conjugate matching.

The AZM PECL parts you use are relatively recent vintage.

Me? I'm not weird. But you sure are :-)

You're the one having trouble coping with conservation.

Bwahahahahahaha! That last NY project... I ended up being the system architect. Rather nicely done. The Cadence team, brought in to do the overall simulations, including the inserted microprocessor (purchased IP, and not simulatable in PSpice), thought my work was marvelous.

There's a world of difference between automotive alternators and bicycle "dynamos".

Oh, yes, before I forget, Kiss MY Ass :-) ...Jim Thompson