Automotive alternator windings & rectifier

[Mike Cook]

http://www.autoshop101.com/forms/alt_bwoh.pdf

has photos of an alternator with 4 connections for windings (each of 3 phases
+ common), and the 8 diode rectifier. But wiring diagrams show only 3
connections and 6 diodes.

Where does the common winding terminal connect (there is a connection on the
rectifier plate)? Where do the other 2 diodes connect?

I handled one of these disassembled units but didn't have time to ohm out the
connections.

Thanks.

 

[amdx]

On 8/19/2013 11:49 AM, Mike Cook wrote:

http://www.autoshop101.com/forms/alt_bwoh.pdf

has photos of an alternator with 4 connections for windings (each of 3 phases
+ common),

Not one of the pages shows four connections brought out from the
windings.


>and the 8 diode rectifier.

I don't see any 8 diode rectifier.

But wiring diagrams show only 3
connections and 6 diodes.

Yup.

Where does the common winding terminal connect (there is a connection on the
rectifier plate)? Where do the other 2 diodes connect?

Common is created by the way the diodes are connected. >THAT< common is
connected to the auto frame.

I handled one of these disassembled units but didn't have time to ohm out the
connections.

Hmm.

Thanks.

Wo uld you ask your question again and maybe clarify the situation?

 

[Jim Thompson]

On Mon, 19 Aug 2013 09:49:18 -0700, Mike Cook <mcham@NOTyahoo.com>
wrote:

http://www.autoshop101.com/forms/alt_bwoh.pdf

has photos of an alternator with 4 connections for windings (each of 3 phases
+ common), and the 8 diode rectifier. But wiring diagrams show only 3
connections and 6 diodes.

Where does the common winding terminal connect (there is a connection on the
rectifier plate)? Where do the other 2 diodes connect?

I handled one of these disassembled units but didn't have time to ohm out the
connections.

Thanks.

The common point is sometimes used for fault detection.

When I was at Motorola SPD in the '60's I developed a circuit that
could detect just about any fault, shorted or open diodes and shorted
or open windings, by viewing that node. That node, BTW, is often
labeled "S". Old GM alternators brought that out as a post on the
back of the alternator (before regulators were internal... that's what
some of my patents are all about... integrating the regulator).

That was before CAD ;-) If I can find my hand drawing, I'll post it.

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Spehro Pefhany]

On Mon, 19 Aug 2013 09:49:18 -0700, Mike Cook <mcham@NOTyahoo.com>
wrote:

http://www.autoshop101.com/forms/alt_bwoh.pdf

has photos of an alternator with 4 connections for windings (each of 3 phases
+ common), and the 8 diode rectifier. But wiring diagrams show only 3
connections and 6 diodes.

Where does the common winding terminal connect (there is a connection on the
rectifier plate)? Where do the other 2 diodes connect?

The common in the Wye connection (called "Neutral Junction" in the
photo on page 18) goes to the 4th pair of diodes (and typically the
regulator). The other three pairs of winding ends ("Stator Lead Ends")
go to the other three pairs of diodes.

I handled one of these disassembled units but didn't have time to ohm out the
connections.

Thanks.

 

[Cydrome Leader]

In sci.electronics.basics Jim Thompson <To-Email-Use-The-Envelope-Icon@on-my-web-site.com> wrote:

On Mon, 19 Aug 2013 09:49:18 -0700, Mike Cook <mcham@NOTyahoo.com
wrote:

http://www.autoshop101.com/forms/alt_bwoh.pdf

has photos of an alternator with 4 connections for windings (each of 3 phases
+ common), and the 8 diode rectifier. But wiring diagrams show only 3
connections and 6 diodes.

Where does the common winding terminal connect (there is a connection on the
rectifier plate)? Where do the other 2 diodes connect?

I handled one of these disassembled units but didn't have time to ohm out the
connections.

Thanks.

The common point is sometimes used for fault detection.

When I was at Motorola SPD in the '60's I developed a circuit that
could detect just about any fault, shorted or open diodes and shorted
or open windings, by viewing that node. That node, BTW, is often
labeled "S". Old GM alternators brought that out as a post on the
back of the alternator (before regulators were internal... that's what
some of my patents are all about... integrating the regulator).

That was before CAD ;-) If I can find my hand drawing, I'll post it.

...Jim Thompson

dumb question.

what EXACTLY does the charge lamp indicate?

what triggers it to go on and off?

can it simply be removed and ignored?

 

[Mike Perkins]

On 19/08/2013 18:42, Spehro Pefhany wrote:

On Mon, 19 Aug 2013 09:49:18 -0700, Mike Cook <mcham@NOTyahoo.com
wrote:

http://www.autoshop101.com/forms/alt_bwoh.pdf

has photos of an alternator with 4 connections for windings (each
of 3 phases + common), and the 8 diode rectifier. But wiring
diagrams show only 3 connections and 6 diodes.

Where does the common winding terminal connect (there is a
connection on the rectifier plate)? Where do the other 2 diodes
connect?

The common in the Wye connection (called "Neutral Junction" in the
photo on page 18) goes to the 4th pair of diodes (and typically the
regulator). The other three pairs of winding ends ("Stator Lead
Ends") go to the other three pairs of diodes.

Not the alternators I've taken apart. The star point is typically a
crimp, and serves no other useful purpose.

The field, and regulator power, are normally taken from an additional set of
diodes, usually 3, ie one per phase, such that the regulator is
effectively isolated from the battery when the engine is not turning.

--
Mike Perkins
Video Solutions Ltd
www.videosolutions.ltd.uk

 

[tm]

"Cydrome Leader" <presence@MUNGEpanix.com> wrote in message
news:kuu98f$jtp$1@reader1.panix.com...

In sci.electronics.basics Jim Thompson
To-Email-Use-The-Envelope-Icon@on-my-web-site.com> wrote:
On Mon, 19 Aug 2013 09:49:18 -0700, Mike Cook <mcham@NOTyahoo.com
wrote:

http://www.autoshop101.com/forms/alt_bwoh.pdf

has photos of an alternator with 4 connections for windings (each of 3
phases
+ common), and the 8 diode rectifier. But wiring diagrams show only 3
connections and 6 diodes.

Where does the common winding terminal connect (there is a connection on
the
rectifier plate)? Where do the other 2 diodes connect?

I handled one of these disassembled units but didn't have time to ohm out
the
connections.

Thanks.

The common point is sometimes used for fault detection.

When I was at Motorola SPD in the '60's I developed a circuit that
could detect just about any fault, shorted or open diodes and shorted
or open windings, by viewing that node. That node, BTW, is often
labeled "S". Old GM alternators brought that out as a post on the
back of the alternator (before regulators were internal... that's what
some of my patents are all about... integrating the regulator).

That was before CAD ;-) If I can find my hand drawing, I'll post it.

...Jim Thompson

dumb question.

what EXACTLY does the charge lamp indicate?

what triggers it to go on and off?

can it simply be removed and ignored?

One cause that can light the lamp is a broken belt. You would like to know
as soon as that happens.

 

[Jim Thompson]

On Mon, 19 Aug 2013 23:20:47 +0000 (UTC), Cydrome Leader
<presence@MUNGEpanix.com> wrote:

In sci.electronics.basics Jim Thompson <To-Email-Use-The-Envelope-Icon@on-my-web-site.com> wrote:
On Mon, 19 Aug 2013 09:49:18 -0700, Mike Cook <mcham@NOTyahoo.com
wrote:

http://www.autoshop101.com/forms/alt_bwoh.pdf

has photos of an alternator with 4 connections for windings (each of 3 phases
+ common), and the 8 diode rectifier. But wiring diagrams show only 3
connections and 6 diodes.

Where does the common winding terminal connect (there is a connection on the
rectifier plate)? Where do the other 2 diodes connect?

I handled one of these disassembled units but didn't have time to ohm out the
connections.

Thanks.

The common point is sometimes used for fault detection.

When I was at Motorola SPD in the '60's I developed a circuit that
could detect just about any fault, shorted or open diodes and shorted
or open windings, by viewing that node. That node, BTW, is often
labeled "S". Old GM alternators brought that out as a post on the
back of the alternator (before regulators were internal... that's what
some of my patents are all about... integrating the regulator).

That was before CAD ;-) If I can find my hand drawing, I'll post it.

...Jim Thompson

dumb question.

what EXACTLY does the charge lamp indicate?

what triggers it to go on and off?

can it simply be removed and ignored?

It's called an "IDIOT" light for a reason... as presently implemented
it mostly tells you that the alternator is turning and has current in
the field winding.

As I designed, the circuit compared the average value of "S" with 1/2
of the "A" terminal. Deviations were correlated with fault type.

Some GM versions enable the alternator regulator to function, so you
can't remove it. (Saves GM the cost of a wire ;-)

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[David Lesher]

Mike Perkins <spam@spam.com> writes:

Where does the common winding terminal connect (there is a
connection on the rectifier plate)? Where do the other 2 diodes
connect?

That pictured alternator is one used on Hondas. ISTM it's a
Nippon-Densi or such.

I have too much experience with same. I went through 3-4
boneyard ones before I bought a rebuilt one from Retarded Auto
Parts. That brand/model alternator is nice because the diode
array unscrews easily. No unsoldering needed.

That particular alternator has 4 pairs of power diodes; the
center point of the wye has a pair from there as well.... and I
have no idea why... Jim??

That said, all recent alternators also have a diode trio of tiny
diodes. Their function is to rectify enough power to excite the
rotor. It takes a few amps to drive it. Until it's up to speed,
that excitation comes from the battery, through the red idiot
light. When the alternator is up to speed, there is 12V on the
battery side of the lamp, and 12v on the load side....and it
goes out.



--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

 

[Spehro Pefhany]

On Mon, 19 Aug 2013 22:32:24 +0100, the renowned Mike Perkins
<spam@spam.com> wrote:

On 19/08/2013 18:42, Spehro Pefhany wrote:
On Mon, 19 Aug 2013 09:49:18 -0700, Mike Cook <mcham@NOTyahoo.com
wrote:

http://www.autoshop101.com/forms/alt_bwoh.pdf

has photos of an alternator with 4 connections for windings (each
of 3 phases + common), and the 8 diode rectifier. But wiring
diagrams show only 3 connections and 6 diodes.

Where does the common winding terminal connect (there is a
connection on the rectifier plate)? Where do the other 2 diodes
connect?

The common in the Wye connection (called "Neutral Junction" in the
photo on page 18) goes to the 4th pair of diodes (and typically the
regulator). The other three pairs of winding ends ("Stator Lead
Ends") go to the other three pairs of diodes.


Not the alternators I've taken apart. The star point is typically a
crimp, and serves no other useful purpose.

Those were alternators with only six power rectifiers, right?

The field, and regulator power, are normally taken from an additional set of
diodes, usually 3, ie one per phase, such that the regulator is
effectively isolated from the battery when the engine is not turning.

The power rectifiers connected to the Wye common are used to extract
3rd harmonic power- yielding up to 10% additional current capacity-
when operating at high speed.



Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

 

[David Platt]

In article <kuur1k$917$1@reader1.panix.com>,
David Lesher <wb8foz@panix.com> wrote:

That said, all recent alternators also have a diode trio of tiny
diodes. Their function is to rectify enough power to excite the
rotor. It takes a few amps to drive it. Until it's up to speed,
that excitation comes from the battery, through the red idiot
light. When the alternator is up to speed, there is 12V on the
battery side of the lamp, and 12v on the load side....and it
goes out.

One problem with this arrangement... if the red idiot light burns out
or a wiring fault opens the circuit, the alternator won't "bootstrap"
the next time you start the car, and you won't (of course) get any
red-light warning. Dead battery, here we come.

Ask me how I know :-(

 

[Mike Cook]

Not the alternators I've taken apart. The star point is typically a
crimp, and serves no other useful purpose.

The field, and regulator power, are normally taken from an additional set of
diodes, usually 3, ie one per phase, such that the regulator is
effectively isolated from the battery when the engine is not turning.

But THAT'S why I'm asking here: this Denso alternator (used in MANY Hondas,
Toyotas, and myriad other makes) does have a common terminal connection to
the rectifier. The rectifier has EIGHT diodes.

Yes I agree that common configuration is 6 diodes. That's why I'm confused.
The system is quite populous and apparently functions. I just don't
understand how.

 

[Fester Bestertester]

One problem with this arrangement... if the red idiot light burns out
or a wiring fault opens the circuit, the alternator won't "bootstrap"
the next time you start the car, and you won't (of course) get any
red-light warning. Dead battery, here we come.

Ask me how I know :-(

That's why you LOOK at the Idiot Light when you turn the ignition switch on,
just before you start the engine. A lit ALT bulb means it is present and
functioning.

 

[Mike Perkins]

On 20/08/2013 06:33, Spehro Pefhany wrote:

On Mon, 19 Aug 2013 22:32:24 +0100, the renowned Mike Perkins
spam@spam.com> wrote:

On 19/08/2013 18:42, Spehro Pefhany wrote:
On Mon, 19 Aug 2013 09:49:18 -0700, Mike Cook
mcham@NOTyahoo.com> wrote:

http://www.autoshop101.com/forms/alt_bwoh.pdf

has photos of an alternator with 4 connections for windings
(each of 3 phases + common), and the 8 diode rectifier. But
wiring diagrams show only 3 connections and 6 diodes.

Where does the common winding terminal connect (there is a
connection on the rectifier plate)? Where do the other 2
diodes connect?

The common in the Wye connection (called "Neutral Junction" in
the photo on page 18) goes to the 4th pair of diodes (and
typically the regulator). The other three pairs of winding ends
("Stator Lead Ends") go to the other three pairs of diodes.


Not the alternators I've taken apart. The star point is typically
a crimp, and serves no other useful purpose.

Those were alternators with only six power rectifiers, right?

Yes.

The field, and regulator power, are normally taken from an
additional set of diodes, usually 3, ie one per phase, such that
the regulator is effectively isolated from the battery when the
engine is not turning.

The power rectifiers connected to the Wye common are used to extract
3rd harmonic power- yielding up to 10% additional current capacity-
when operating at high speed.

Thanks, I've learnt something today. I was aware that harmonic neutral
currents are an issue with mains supplies but never thought they might
be an advantage here.


--
Mike Perkins
Video Solutions Ltd
www.videosolutions.ltd.uk

 

[Mike Perkins]

On 20/08/2013 08:04, Mike Cook wrote:

Not the alternators I've taken apart. The star point is typically
a crimp, and serves no other useful purpose.

The field, and regulator power, are normally taken from an
additional set of diodes, usually 3, ie one per phase, such that
the regulator is effectively isolated from the battery when the
engine is not turning.

But THAT'S why I'm asking here: this Denso alternator (used in MANY
Hondas, Toyotas, and myriad other makes) does have a common terminal
connection to the rectifier. The rectifier has EIGHT diodes.

Yes I agree that common configuration is 6 diodes. That's why I'm
confused. The system is quite populous and apparently functions. I
just don't understand how.

I can find very little on the web regarding neutral point rectification
for car (Lundell) alternators, but there is a lot about 3rd harmonic
neutral currents. An example how these manifest in electrical systems
for non-linear loads.

http://static.schneider-electric.us/docs/Electrical%20Distribution/Low%20Voltage%20Transformers/Harmonic%20Mitigating/0104ED9501R896.pdf

A conventional automotive alternator uses six diodes to rectify
three-phase AC (Alternating Current) into DC (Direct Current). The
average voltage of the neutral point is 1/2 of the output DC voltage.
While a low output current flows, the voltage at the neutral point is
mostly DC, but it also includes an AC portion. As current output
increases, the AC portion increases.

When the alternator speed exceeds 2,000 to 3,000 rpm, the peak value of
this AC portion exceeds the DC output voltage.

This means that, compared with the output characteristics of the
alternator without neutral-point diodes, the output gradually increases
from midway by 10 to 15% at a normal rated alternator speed of approx.
5,000 rpm.

http://youronlinemechanic.com/alternator-with-neutral-point-voltage/

--
Mike Perkins
Video Solutions Ltd
www.videosolutions.ltd.uk

 

[Jasen Betts]

On 2013-08-19, Cydrome Leader <presence@MUNGEpanix.com> wrote:

dumb question.

what EXACTLY does the charge lamp indicate?

current into the regulator not supplied by the altenator.

> what triggers it to go on and off?

basically a working altenator.

> can it simply be removed and ignored?

you could replace it with a short circuit

--
⚂⚃ 100% natural

--- news://freenews.netfront.net/ - complaints: news@netfront.net ---

 

[Jim Thompson]

On Tue, 20 Aug 2013 04:24:20 +0000 (UTC), David Lesher
<wb8foz@panix.com> wrote:

Mike Perkins <spam@spam.com> writes:

Where does the common winding terminal connect (there is a
connection on the rectifier plate)? Where do the other 2 diodes
connect?


That pictured alternator is one used on Hondas. ISTM it's a
Nippon-Densi or such.

I have too much experience with same. I went through 3-4
boneyard ones before I bought a rebuilt one from Retarded Auto
Parts. That brand/model alternator is nice because the diode
array unscrews easily. No unsoldering needed.

That particular alternator has 4 pairs of power diodes; the
center point of the wye has a pair from there as well.... and I
have no idea why... Jim??

They are a multitude of ways to implement the "idiot light" function,
some used relays, some were a part of the regulator.

I'm in the midst of moving right now, old house sold faster than new
one's construction, so I'm stuck in a snow-bird friend's loaner with
no access to my (paper) file cabinets.

When I get back on the air I'll retrieve those drawings and post.

Keep in mind I did no automotive after about 1973, so I'm not up on
any modern approaches.

That said, all recent alternators also have a diode trio of tiny
diodes. Their function is to rectify enough power to excite the
rotor. It takes a few amps to drive it. Until it's up to speed,
that excitation comes from the battery, through the red idiot
light. When the alternator is up to speed, there is 12V on the
battery side of the lamp, and 12v on the load side....and it
goes out.

Or, like many GM alternators, the rotor was mildly magnetized to
provide "kick-start", minimum load requirement hidden by the
"daylight-safety" headlamp BS ;-)

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Cydrome Leader]

In sci.electronics.equipment Mike Perkins <spam@spam.com> wrote:

On 20/08/2013 08:04, Mike Cook wrote:
Not the alternators I've taken apart. The star point is typically
a crimp, and serves no other useful purpose.

The field, and regulator power, are normally taken from an
additional set of diodes, usually 3, ie one per phase, such that
the regulator is effectively isolated from the battery when the
engine is not turning.

But THAT'S why I'm asking here: this Denso alternator (used in MANY
Hondas, Toyotas, and myriad other makes) does have a common terminal
connection to the rectifier. The rectifier has EIGHT diodes.

Yes I agree that common configuration is 6 diodes. That's why I'm
confused. The system is quite populous and apparently functions. I
just don't understand how.

I can find very little on the web regarding neutral point rectification
for car (Lundell) alternators, but there is a lot about 3rd harmonic
neutral currents. An example how these manifest in electrical systems
for non-linear loads.

http://static.schneider-electric.us/docs/Electrical%20Distribution/Low%20Voltage%20Transformers/Harmonic%20Mitigating/0104ED9501R896.pdf

A conventional automotive alternator uses six diodes to rectify
three-phase AC (Alternating Current) into DC (Direct Current). The
average voltage of the neutral point is 1/2 of the output DC voltage.
While a low output current flows, the voltage at the neutral point is
mostly DC, but it also includes an AC portion. As current output
increases, the AC portion increases.

When the alternator speed exceeds 2,000 to 3,000 rpm, the peak value of
this AC portion exceeds the DC output voltage.

This means that, compared with the output characteristics of the
alternator without neutral-point diodes, the output gradually increases
from midway by 10 to 15% at a normal rated alternator speed of approx.
5,000 rpm.

http://youronlinemechanic.com/alternator-with-neutral-point-voltage/

Here's a diagram of what the above link failed to clearly explain

http://autonopedia.org/renewable-energy/generators/alternator-secrets/

so somehow tapping neutral is good. I guess those two diodes bypass
current flowing int coils the wrong way or something? As to how speed
matters, I'm not following that.

 

[Mike Perkins]

On 21/08/2013 00:47, Cydrome Leader wrote:

In sci.electronics.equipment Mike Perkins <spam@spam.com> wrote:
On 20/08/2013 08:04, Mike Cook wrote:
Not the alternators I've taken apart. The star point is typically
a crimp, and serves no other useful purpose.

The field, and regulator power, are normally taken from an
additional set of diodes, usually 3, ie one per phase, such that
the regulator is effectively isolated from the battery when the
engine is not turning.

But THAT'S why I'm asking here: this Denso alternator (used in MANY
Hondas, Toyotas, and myriad other makes) does have a common terminal
connection to the rectifier. The rectifier has EIGHT diodes.

Yes I agree that common configuration is 6 diodes. That's why I'm
confused. The system is quite populous and apparently functions. I
just don't understand how.

I can find very little on the web regarding neutral point rectification
for car (Lundell) alternators, but there is a lot about 3rd harmonic
neutral currents. An example how these manifest in electrical systems
for non-linear loads.

http://static.schneider-electric.us/docs/Electrical%20Distribution/Low%20Voltage%20Transformers/Harmonic%20Mitigating/0104ED9501R896.pdf

A conventional automotive alternator uses six diodes to rectify
three-phase AC (Alternating Current) into DC (Direct Current). The
average voltage of the neutral point is 1/2 of the output DC voltage.
While a low output current flows, the voltage at the neutral point is
mostly DC, but it also includes an AC portion. As current output
increases, the AC portion increases.

When the alternator speed exceeds 2,000 to 3,000 rpm, the peak value of
this AC portion exceeds the DC output voltage.

This means that, compared with the output characteristics of the
alternator without neutral-point diodes, the output gradually increases
from midway by 10 to 15% at a normal rated alternator speed of approx.
5,000 rpm.

http://youronlinemechanic.com/alternator-with-neutral-point-voltage/

Here's a diagram of what the above link failed to clearly explain

http://autonopedia.org/renewable-energy/generators/alternator-secrets/

so somehow tapping neutral is good. I guess those two diodes bypass
current flowing int coils the wrong way or something? As to how speed
matters, I'm not following that.

If you consider that at any time 2 windings will be supplying one
polarity of current and the remaining winding the other polarity, you
can see the neutral point is going to move in the direction dictated by
the two windings. At higher currents, and higher frequencies, the
inductance of the winding causes an increasing voltage to appear at the
neutral point.

--
Mike Perkins
Video Solutions Ltd
www.videosolutions.ltd.uk

 

[Don Kelly]

On 19/08/2013 10:33 PM, Spehro Pefhany wrote:

The power rectifiers connected to the Wye common are used to extract
3rd harmonic power- yielding up to 10% additional current capacity-
when operating at high speed.

That doesn't make sense to me. One advantage of 3 phase is the
elimination of triplen harmonics. Now, with a 3 phase bridge-will there
be a significant 3rd harmonic voltage? Certainly,if the wye neutral is
not connected to the DC ground, there is no 3rd harmonic current and
power. Generally this is a good thing.
Somehow, I appear to be missing something-could you elucidate? A circuit
diagram and analysis would help.

--
Don Kelly
remove the cross to reply