Deere alternator

I'm learning about PM alternators, waiting for an aircraft 3-phase 400
Hz unit, so I ordered a single-phase John Deere rider lawn mower
replacement unit, $50 from Amazon, to play with.

https://www.dropbox.com/sh/akspv8qv4c6u2tz/AACHKKJQSkDOvP5gxZTR66F_a?dl=0

There are 12 stator coils, all in series but opposite winding
direction on alternate coils. I haven't figured out the rotor magnets,
but they are probably simple N-S-N-S radial fields.

The detent is really hard.

 

On Sat, 24 Aug 2019 11:48:14 -0700, jlarkin@highlandsniptechnology.com
wrote:

I'm learning about PM alternators, waiting for an aircraft 3-phase 400
Hz unit, so I ordered a single-phase John Deere rider lawn mower
replacement unit, $50 from Amazon, to play with.

https://www.dropbox.com/sh/akspv8qv4c6u2tz/AACHKKJQSkDOvP5gxZTR66F_a?dl=0

There are 12 stator coils, all in series but opposite winding
direction on alternate coils. I haven't figured out the rotor magnets,
but they are probably simple N-S-N-S radial fields.

The detent is really hard.

Maybe the magnets are magnetized in their long directions,
circumferential field, making a closed magnetic ring with small gaps.
That would better correspond to the very strong detents.

A pair of coils bridges a magnetic gap. One detent later, they bridge
the gap again, but the induced voltage direction is reversed.

 

[Winfield Hill]

jlarkin@highlandsniptechnology.com wrote...

On 24 Aug 2019, jlarkin@highlandsniptechnology.com wrote:

I'm learning about PM alternators, waiting for an aircraft
3-phase 400Hz unit, so I ordered a single-phase John Deere
rider lawn mower replacement unit, $50 from Amazon, to play with.

https://www.dropbox.com/sh/akspv8qv4c6u2tz/AACHKKJQSkDOvP5gxZTR66F_a?dl=0

There are 12 stator coils, all in series but opposite winding
direction on alternate coils. I haven't figured out the rotor
magnets, but they are probably simple N-S-N-S radial fields.

The detent is really hard.

Maybe the magnets are magnetized in their long directions,
circumferential field, making a closed magnetic ring with small
gaps. That would better correspond to the very strong detents.

A pair of coils bridges a magnetic gap. One detent later, they
bridge the gap again, but the induced voltage direction is reversed.

It looks like there's three coils and pole pieces per
magnet section. Is it 3-phase into the diodes? Tell
us how to understand it.


--
Thanks,
- Win

 

On 31 Aug 2019 10:44:15 -0700, Winfield Hill <winfieldhill@yahoo.com>
wrote:

jlarkin@highlandsniptechnology.com wrote...
On 24 Aug 2019, jlarkin@highlandsniptechnology.com wrote:

I'm learning about PM alternators, waiting for an aircraft
3-phase 400Hz unit, so I ordered a single-phase John Deere
rider lawn mower replacement unit, $50 from Amazon, to play with.

https://www.dropbox.com/sh/akspv8qv4c6u2tz/AACHKKJQSkDOvP5gxZTR66F_a?dl=0

There are 12 stator coils, all in series but opposite winding
direction on alternate coils. I haven't figured out the rotor
magnets, but they are probably simple N-S-N-S radial fields.

The detent is really hard.

Maybe the magnets are magnetized in their long directions,
circumferential field, making a closed magnetic ring with small
gaps. That would better correspond to the very strong detents.

A pair of coils bridges a magnetic gap. One detent later, they
bridge the gap again, but the induced voltage direction is reversed.

It looks like there's three coils and pole pieces per
magnet section. Is it 3-phase into the diodes? Tell
us how to understand it.

It's single phase, AC output, just a pair of wires connected to all 12
coils in series.

I assue that the action happens at the four gaps in the circular PM
loop, so only four sites are active at a time.

 

[Winfield Hill]

jlarkin@highlandsniptechnology.com wrote...

On 31 Aug 2019, Winfield Hill wrote:
jlarkin@highlandsniptechnology.com wrote...
On 24 Aug 2019, jlarkin@highlandsniptechnology.com wrote:

I'm learning about PM alternators, waiting for an aircraft
3-phase 400Hz unit, so I ordered a single-phase John Deere
rider lawn mower replacement unit, $50 from Amazon, to play with.

https://www.dropbox.com/sh/akspv8qv4c6u2tz/AACHKKJQSkDOvP5gxZTR66F_a?dl=0

There are 12 stator coils, all in series but opposite winding
direction on alternate coils. I haven't figured out the rotor
magnets, but they are probably simple N-S-N-S radial fields.

The detent is really hard.

Maybe the magnets are magnetized in their long directions,
circumferential field, making a closed magnetic ring with small
gaps. That would better correspond to the very strong detents.

A pair of coils bridges a magnetic gap. One detent later, they
bridge the gap again, but the induced voltage direction is reversed.

It looks like there's three coils and pole pieces per
magnet section. Is it 3-phase into the diodes? Tell
us how to understand it.

It's single phase, AC output, just a pair of wires connected to
all 12 coils in series.

I assume that the action happens at the four gaps in the
circular PM loop, so only four sites are active at a time.

Thanks, John for telling us about it. One more thing to understand.


--
Thanks,
- Win

 

On 3 Sep 2019 17:03:10 -0700, Winfield Hill <winfieldhill@yahoo.com>
wrote:

jlarkin@highlandsniptechnology.com wrote...

On 31 Aug 2019, Winfield Hill wrote:
jlarkin@highlandsniptechnology.com wrote...
On 24 Aug 2019, jlarkin@highlandsniptechnology.com wrote:

I'm learning about PM alternators, waiting for an aircraft
3-phase 400Hz unit, so I ordered a single-phase John Deere
rider lawn mower replacement unit, $50 from Amazon, to play with.

https://www.dropbox.com/sh/akspv8qv4c6u2tz/AACHKKJQSkDOvP5gxZTR66F_a?dl=0

There are 12 stator coils, all in series but opposite winding
direction on alternate coils. I haven't figured out the rotor
magnets, but they are probably simple N-S-N-S radial fields.

The detent is really hard.

Maybe the magnets are magnetized in their long directions,
circumferential field, making a closed magnetic ring with small
gaps. That would better correspond to the very strong detents.

A pair of coils bridges a magnetic gap. One detent later, they
bridge the gap again, but the induced voltage direction is reversed.

It looks like there's three coils and pole pieces per
magnet section. Is it 3-phase into the diodes? Tell
us how to understand it.

It's single phase, AC output, just a pair of wires connected to
all 12 coils in series.

I assume that the action happens at the four gaps in the
circular PM loop, so only four sites are active at a time.

Thanks, John for telling us about it. One more thing to understand.

These things usually drive a bridge rectifier and a cap, or a battery,
and are regulated by shorting the alternator. It's mostly inductive so
doesn't much mind being shorted. Open-circuit voltage could be very
high, which is why a series regulator isn't a good idea.

 

[Phil Hobbs]

On 9/3/19 8:29 PM, jlarkin@highlandsniptechnology.com wrote:

On 3 Sep 2019 17:03:10 -0700, Winfield Hill <winfieldhill@yahoo.com
wrote:

jlarkin@highlandsniptechnology.com wrote...

On 31 Aug 2019, Winfield Hill wrote:
jlarkin@highlandsniptechnology.com wrote...
On 24 Aug 2019, jlarkin@highlandsniptechnology.com wrote:

I'm learning about PM alternators, waiting for an aircraft
3-phase 400Hz unit, so I ordered a single-phase John Deere
rider lawn mower replacement unit, $50 from Amazon, to play with.

https://www.dropbox.com/sh/akspv8qv4c6u2tz/AACHKKJQSkDOvP5gxZTR66F_a?dl=0

There are 12 stator coils, all in series but opposite winding
direction on alternate coils. I haven't figured out the rotor
magnets, but they are probably simple N-S-N-S radial fields.

The detent is really hard.

Maybe the magnets are magnetized in their long directions,
circumferential field, making a closed magnetic ring with small
gaps. That would better correspond to the very strong detents.

A pair of coils bridges a magnetic gap. One detent later, they
bridge the gap again, but the induced voltage direction is reversed.

It looks like there's three coils and pole pieces per
magnet section. Is it 3-phase into the diodes? Tell
us how to understand it.

It's single phase, AC output, just a pair of wires connected to
all 12 coils in series.

I assume that the action happens at the four gaps in the
circular PM loop, so only four sites are active at a time.

Thanks, John for telling us about it. One more thing to understand.

These things usually drive a bridge rectifier and a cap, or a battery,
and are regulated by shorting the alternator. It's mostly inductive so
doesn't much mind being shorted. Open-circuit voltage could be very
high, which is why a series regulator isn't a good idea.

So it's really more like a magneto, then. Interesting!

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

On Wed, 4 Sep 2019 06:12:00 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 9/3/19 8:29 PM, jlarkin@highlandsniptechnology.com wrote:
On 3 Sep 2019 17:03:10 -0700, Winfield Hill <winfieldhill@yahoo.com
wrote:

jlarkin@highlandsniptechnology.com wrote...

On 31 Aug 2019, Winfield Hill wrote:
jlarkin@highlandsniptechnology.com wrote...
On 24 Aug 2019, jlarkin@highlandsniptechnology.com wrote:

I'm learning about PM alternators, waiting for an aircraft
3-phase 400Hz unit, so I ordered a single-phase John Deere
rider lawn mower replacement unit, $50 from Amazon, to play with.

https://www.dropbox.com/sh/akspv8qv4c6u2tz/AACHKKJQSkDOvP5gxZTR66F_a?dl=0

There are 12 stator coils, all in series but opposite winding
direction on alternate coils. I haven't figured out the rotor
magnets, but they are probably simple N-S-N-S radial fields.

The detent is really hard.

Maybe the magnets are magnetized in their long directions,
circumferential field, making a closed magnetic ring with small
gaps. That would better correspond to the very strong detents.

A pair of coils bridges a magnetic gap. One detent later, they
bridge the gap again, but the induced voltage direction is reversed.

It looks like there's three coils and pole pieces per
magnet section. Is it 3-phase into the diodes? Tell
us how to understand it.

It's single phase, AC output, just a pair of wires connected to
all 12 coils in series.

I assume that the action happens at the four gaps in the
circular PM loop, so only four sites are active at a time.

Thanks, John for telling us about it. One more thing to understand.

These things usually drive a bridge rectifier and a cap, or a battery,
and are regulated by shorting the alternator. It's mostly inductive so
doesn't much mind being shorted. Open-circuit voltage could be very
high, which is why a series regulator isn't a good idea.


So it's really more like a magneto, then. Interesting!

Cheers

Phil Hobbs

Most magnetos had a set of points to keep the coil shorted as the mag
field built up. At the critical time, about at peak current, a cam
pushed the points open and there was a voltage kick. I think the
points may have shorted only a part of the winding, to make more
voltage into the spark plug than points could break. Or there was a
separate step-up coil.

PM things like this are, when the speed over-runs the L/R time
constant, approximately AC constant-current sources. Ideal for
charging a bettery.

We're being asked to provide a 3-phase AC power source programmable
for frequency, voltage, inductance, and resistance per phase, to
simulate a PM alternator that runs an engine control computer. The
customer is tied in the currently popular security knots as regards
giving us any real numbers or waveforms to work with, so I'm reduced
to buying lawn mower repair parts.

My Yamaha 250 had a magneto ignition. It was enormous fun. I must have
crashed a few hundred times, dirt riding (illegally) in the Bonnet
Carre' Spillway and some old gravel pits and such.

https://www.facebook.com/NOLAnews/videos/time-lapse-of-bonnet-carre-spillway-opening/396304597866414/

 

Most magnetos had a set of points to keep the coil shorted as the mag
field built up. At the critical time, about at peak current, a cam
pushed the points open and there was a voltage kick. I think the
points may have shorted only a part of the winding, to make more
voltage into the spark plug than points could break. Or there was a
separate step-up coil.

PM things like this are, when the speed over-runs the L/R time
constant, approximately AC constant-current sources. Ideal for
charging a battery.

I was thinking of a bicycle magneto rather than an IC engine.

Cheers

Phil Hobbs

 

On Wed, 4 Sep 2019 08:16:37 -0700 (PDT), pcdhobbs@gmail.com wrote:

Most magnetos had a set of points to keep the coil shorted as the mag
field built up. At the critical time, about at peak current, a cam
pushed the points open and there was a voltage kick. I think the
points may have shorted only a part of the winding, to make more
voltage into the spark plug than points could break. Or there was a
separate step-up coil.

PM things like this are, when the speed over-runs the L/R time
constant, approximately AC constant-current sources. Ideal for
charging a battery.

I was thinking of a bicycle magneto rather than an IC engine.

Cheers

Phil Hobbs

OK, the constant-current effect is good there too.

 

[John Larkin]

On Fri, 6 Sep 2019 12:02:51 -0700 (PDT),
bloggs.fredbloggs.fred@gmail.com wrote:

On Saturday, August 24, 2019 at 2:48:21 PM UTC-4, jla...@highlandsniptechnology.com wrote:
I'm learning about PM alternators, waiting for an aircraft 3-phase 400
Hz unit, so I ordered a single-phase John Deere rider lawn mower
replacement unit, $50 from Amazon, to play with.

https://www.dropbox.com/sh/akspv8qv4c6u2tz/AACHKKJQSkDOvP5gxZTR66F_a?dl=0

There are 12 stator coils, all in series but opposite winding
direction on alternate coils. I haven't figured out the rotor magnets,
but they are probably simple N-S-N-S radial fields.

The detent is really hard.

I'm pretty sure Deere doesn't make engines. The small stuff is either Briggs & Stratton or Kohler, custom manu'd to Deere specs. The alternators should be the same. Looks like a bunch of stator coils in series and a PM armature. Deere and Kubota are the most expensive parts you can buy. You can get B&S and Kohler for significantly less, like maybe half price.

I got a Chinese copy replacement Deere unit, which looks very nice.
But I really need a genuine jet engine FADEC power alternator, which I
haven't been able to find for retail sale. There must be an old one
out in the rain out back somewhere.

Something like this:

https://www.oeco.com/wp-content/uploads/2015/07/5591.pdf

very different from the Deere.

I asked them what the coil inductance was, and they replied "that's
proprietary."

Looks like redundant 3-phase windings. I get to sell more simulators!

 

On Saturday, August 24, 2019 at 2:48:21 PM UTC-4, jla...@highlandsniptechnology.com wrote:

I'm learning about PM alternators, waiting for an aircraft 3-phase 400
Hz unit, so I ordered a single-phase John Deere rider lawn mower
replacement unit, $50 from Amazon, to play with.

https://www.dropbox.com/sh/akspv8qv4c6u2tz/AACHKKJQSkDOvP5gxZTR66F_a?dl=0

There are 12 stator coils, all in series but opposite winding
direction on alternate coils. I haven't figured out the rotor magnets,
but they are probably simple N-S-N-S radial fields.

The detent is really hard.

I'm pretty sure Deere doesn't make engines. The small stuff is either Briggs & Stratton or Kohler, custom manu'd to Deere specs. The alternators should be the same. Looks like a bunch of stator coils in series and a PM armature. Deere and Kubota are the most expensive parts you can buy. You can get B&S and Kohler for significantly less, like maybe half price.