REGULATOR/RECTIFIER

F

Fernando

Guest
I am needing a rectifier / regulator for motorcycles. The alternator
produces
AC three-phases. If somebody has circuit or can indicate me a Link where I
can
to find some thing, I thank.
Fernando
 
Fernando wrote:
I am needing a rectifier / regulator for motorcycles. The alternator
produces
AC three-phases. If somebody has circuit or can indicate me a Link where I
can
to find some thing, I thank.
Fernando
Click to expand...
Is the alternator excited by permanent magnets (always full on), or
does it have a rotating field winding (and brushes on slip rings) so
that a regulator can control it?
--
John Popelish
 
Hi,

It is a alternator excited by permanent magnets.

Tks
Fernando


"John Popelish" <jpopelish@rica.net> escreveu na mensagem
news:41793C0A.E5935298@rica.net...
Fernando wrote:

I am needing a rectifier / regulator for motorcycles. The alternator
produces
AC three-phases. If somebody has circuit or can indicate me a Link where
I
can
to find some thing, I thank.
Fernando

Is the alternator excited by permanent magnets (always full on), or
does it have a rotating field winding (and brushes on slip rings) so
that a regulator can control it?
--
John Popelish
Click to expand...
 
On Sat, 23 Oct 2004 16:01:29 +0000, Ken Smith wrote:

In article <1098531767.610295@gorgo.centroin.com.br>, Fernando
carvalho@centroin.com.br> wrote:

Hi,

It is a alternator excited by permanent magnets.

This sounds like a place where an SCR phase controlled rectifier would be
the best. Can anyone thing of a reason not to go that way?
Click to expand...
I can't really judge, until I see the circuit you come up with to
time them. :)

Good Luck!
Rich
 
On Sat, 23 Oct 2004 20:18:43 GMT, Rich Grise <rich@example.net> wrote:


This got me to thinking - what a nightmare! But, what's the ripple on
unfiltered, full-wave rectified 3-phase?
---
Click to expand...
about 5%
---




--
John Fields
 
(Ken Smith) wrote:

In article <20041023194348.02596.00002513@mb-m13.aol.com>,
ChrisGibboGibson <chrisgibbogibson@aol.com> wrote:
(Ken Smith) wrote:

[snip]

"We don't need no stinking inductors"


Have you been reading feerguy's bullshit?

"feerguy" ???? huh

I was thinking of the movieline "we don't need no stinking badges"
Click to expand...
No worries. When you're next bored do a search on feerguy or eerguy. He posts
regular bollox on here and he "don't need no stinking" anything in order to
solve all the world's energy problems (including the laws of physics
apparently).

Gibbo
 
In article <pan.2004.10.23.20.26.32.901036@example.net>,
Rich Grise <rich@example.net> wrote:
[...]
This got me to thinking - what a nightmare!
Click to expand...
Huh! Why is thinking a nightmare? :) Or did you mean the design
situation?


But, what's the ripple on
unfiltered, full-wave rectified 3-phase?
Click to expand...
Full wave 3 phase gives 6 peaks per cycle. The peaks are 60 degrees
apart. The dips are at the 30 degree points so its cos(30)=0.866

A lot less than you'd first
think!
Click to expand...
Depends on when you consider "first". If you mean in the 1960s then you
may be right that the first time I thought about it I got it wrong. My,
normally very good, memory fails me on this subject so I can't say for
sure what I first thought the ripple would be.

So, why not just rectify it and chop it?
Click to expand...
(1) It invloves more power semiconductors

(2) I didn't suggest it.

You could free-run
PWM and just filter out both components in the DC. An inductor could
do a lot of filtering at these impedance levels, too.
Click to expand...
"We don't need no stinking inductors"

If the PWM design is any good, the inductor doesn;t have to deal with the
supply voltage ripple.

--
--
kensmith@rahul.net forging knowledge
 
In article <20041023194348.02596.00002513@mb-m13.aol.com>,
ChrisGibboGibson <chrisgibbogibson@aol.com> wrote:
(Ken Smith) wrote:

[snip]

"We don't need no stinking inductors"


Have you been reading feerguy's bullshit?
Click to expand...
"feerguy" ???? huh

I was thinking of the movieline "we don't need no stinking badges"

--
--
kensmith@rahul.net forging knowledge
 
(Ken Smith) wrote:

In article <20041023195816.02596.00002517@mb-m13.aol.com>,
ChrisGibboGibson <chrisgibbogibson@aol.com> wrote:
[...]
No worries. When you're next bored do a search on feerguy or eerguy.
^^^^^^

Oh him!

He isn't even funny anymore.
Click to expand...
"anymore" ? He never was, was he?

Gibbo
 
(Ken Smith) wrote:

In article <20041023200830.02596.00002518@mb-m13.aol.com>,
ChrisGibboGibson <chrisgibbogibson@aol.com> wrote:
(Ken Smith) wrote:
[...]
No worries. When you're next bored do a search on feerguy or eerguy.
^^^^^^

Oh him!

He isn't even funny anymore.


"anymore" ? He never was, was he?

I thought it was the first time I read it. I though someone was pulling
our leg. It seemed so totally unbelievible that I took it as a joke.
Click to expand...
It's odd how different people with different personalities perceive the same
thing.

When I first read it I just assumed he was a complete cockend.

Now when I come across it again in other NGs I often wonder whether he's just
having a laugh. Which is almost the exact opposite of what you seemed to think.

Gibbo
 
In article <20041023200830.02596.00002518@mb-m13.aol.com>,
ChrisGibboGibson <chrisgibbogibson@aol.com> wrote:
(Ken Smith) wrote:
[...]
No worries. When you're next bored do a search on feerguy or eerguy.
^^^^^^

Oh him!

He isn't even funny anymore.


"anymore" ? He never was, was he?
Click to expand...
I thought it was the first time I read it. I though someone was pulling
our leg. It seemed so totally unbelievible that I took it as a joke.


--
--
kensmith@rahul.net forging knowledge
 
In article <pan.2004.10.24.04.35.29.281562@example.net>,
Rich Grise <rich@example.net> wrote:
[...]
My,
normally very good, memory fails me on this subject so I can't say for
sure what I first thought the ripple would be.

At first, you thought of the 200% ripple of the half-wave rectifier,
come on, admit it! ;-P
Click to expand...
No, its more likely that I though 50% or 70.71% or even 63% thos numbes
come up a lot so it must be one of them, right.

[..]
Yes. They tell me that people go to school for many, many years
consecutively to learn the black art of switching regulator design.
Click to expand...
I had to develop much of the theory for myself. When I started at it,
books on the subject were rare and very poorly written. In most cases,
the trick is to consider the switching section to have a "transport
delay". That is there is an increasing phase lag with increasing
frequency but not reduction in gain. In large signal cases, you also have
to consider the "mixer effects". This is where the load variation beats
against the switching frequency. These days, it is easier to use the
simple model to get close and then stuff it into spice for fine tuning.


I've
actually been in the presence of an actual human man who actually knew how
to design ferroresonant transformers.
Click to expand...

Was his name Zambre? He is a man the world will certainly miss.


--
--
kensmith@rahul.net forging knowledge
 
Fernando wrote:
Hi,

It is a alternator excited by permanent magnets.

That type is often designed with a lot of inductance, so that the
Click to expand...
current does not rise in proportion to speed, as long as there is a
significant load current. They also don't like to have a widely
varying load, but are matched to the loads designed into the bike. A
shunt regulator is common with this type or alternator. This is some
big transistor on a heat sink, connected across the alternator output
that sucks up all the excess current, once the voltage rises above
something like 14 or 15 volts.

I think this is an example of such a regulator:
http://www.cranecams.com/pdf/90002500.pdf
http://www.challengers101.com/RotaxChargeSys.html
http://homepage.sunrise.ch/mysunrise/joerg.hau/mot/voltreg.htm

If you try for a more efficient series chopper regulator, you have to
be prepared for wide voltage swings out of the alternator, almost
proportional to speed. So if it puts out 13 volts at 1000 rpm, it
might approach 100 volts at 10,000 rpm, under a light load. The
rectifiers may not like this.

--
John Popelish
 
On Sat, 23 Oct 2004 17:32:46 +0000, Ken Smith wrote:
In article <pan.2004.10.23.16.36.53.640702@example.net>, Rich Grise
On Sat, 23 Oct 2004 16:01:29 +0000, Ken Smith wrote:
In article <1098531767.610295@gorgo.centroin.com.br>, Fernando
It is a alternator excited by permanent magnets.
This sounds like a place where an SCR phase controlled rectifier would
be the best. Can anyone thing of a reason not to go that way?
I can't really judge, until I see the circuit you come up with to time
them. :)

I just discovered a problem with the basic idea. It is not very good at
living through an overload. Unless the alternator has a largish
impedance, the current can be huge and we have to wait a long time for the
SCR to get reverse biased and shut down.

To implement the phase control switch circuit, I thing we need to insert a
current sense resistor (a)in the ground side of the bridge rectifier or
(b) the positive output of the bridge.
....
Click to expand...
This got me to thinking - what a nightmare! But, what's the ripple on
unfiltered, full-wave rectified 3-phase? A lot less than you'd first
think! So, why not just rectify it and chop it? You could free-run
PWM and just filter out both components in the DC. An inductor could
do a lot of filtering at these impedance levels, too.

Good Luck!
Rich
 
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