Split Phase Motor/Generator

[Doug Goncz]

In an earlier thread, "Inpedance Protection of Ceiling Fan Motor" (sic), and
other threads here and in other newsgroups, I have considered the possiblity of
using a split phase capacitor run AC motor as a generator.

I have assembled the motor to my bicycle and it runs the cranks just fine. I
don't intend to build an AC motor powered bicycle with it. After all, what
would you do when the required extension cord pulled out of the wall? It is
useful to have an AC motor on a bicycle. When in the shop for maintenance, all
one need do is plug in the motor and spend a few minutes tuning the
transmission for maximum shift efficiency, saving much time.

From my EET 350 (Fundamentals of Electrical Technology) textbook, "Introduction
to Electricity, Electronics, and Electromagnetism", I see that the torque curve
as a function of speed is sharply sloped near synchronous speed and understand
that it pretty much reflects across the speed axis into the region of negative
(that is, applied) torque, allowing the motor to act as a generator.

I plan to use AC excitation but don't understand how to connect the load so
that the generator will drive it. Certainly the impedance of the wall socket is
very low, while the impedance of my onboard sine wave inverter, which supplies
AC excitation to the motor, may be higher or lower. In any case, I suspect the
impedance of this impedance protected motor to be rather high.

The proposed loads are two: one, a highly efficient white LED signal light
donated by John Viselli at Dialight for this R&D project, and two, an even more
efficient high pressure sodium fixture to be purchased at The Home Depot or
from Grainger when the LED light goes on line.

The LED light is 8W, and is entirely suitable for use as a road headlight, with
its trapezoidal beam pattern, sealed construction, and easy mounting into a
fairing. It can be mounted directly to the motor, for now, it is so light. I
have fabricated one such adapter already, and two model adapters of foam to
carry the "guts" of a simlar light, a green LED traffic light. These weigh
grams.

The sodium fixture is a little heavier, but not too bad. It is rated 35 W and
is entirely suitable for navigating difficult terrain at night, at high speeds.
It's a flood light.

I finished the plastic shell for the road wheel powered DC motor/generator the
other day. This generator will power the inverter, and the inverter will excite
the AC generator. Rider power will be transormed by the generator into AC power
to power the lamp. That's a jump from 60 Hz mechanical power to 60 Hz AC, then
around 33 octaves to visible light. No, this isn't a perpetual motion machine
or a dynamic brake. The AC motor is being used as a generator with AC
excitation supplied by the inverter, which is in turn supplied by the 30 VDC,
12 A stall motor/generator. There's very little drag in the mechanicals. There
are losses, though. Compared to a CVT hub, these losses are acceptable. That
is, ridability has not been affected. I road with the AC generator on chain
drive for several miles the other day. I didn't generate any power but losses
were low.

So how do I establish load sharing between the inverter and AC generator?

That is, how do I excite the generator and seamlessly make use of the generated
power?




Yours,
Doug Goncz ( ftp://users.aol.com/DGoncz/incoming )
Student member SAE for one year.
I love: Dona, Jeff, Kim, Mom, Neelix, Tasha, and Teri, alphabetically.
I drive: A double-step Thunderbolt with 657% range.

 

[Tim Wescott]

In an earlier thread, "Inpedance Protection of Ceiling Fan Motor" (sic), and
other threads here and in other newsgroups, I have considered the possiblity of
using a split phase capacitor run AC motor as a generator.

I have assembled the motor to my bicycle and it runs the cranks just fine. I
don't intend to build an AC motor powered bicycle with it. After all, what
would you do when the required extension cord pulled out of the wall? It is
useful to have an AC motor on a bicycle. When in the shop for maintenance, all
one need do is plug in the motor and spend a few minutes tuning the
transmission for maximum shift efficiency, saving much time.

From my EET 350 (Fundamentals of Electrical Technology) textbook, "Introduction
to Electricity, Electronics, and Electromagnetism", I see that the torque curve
as a function of speed is sharply sloped near synchronous speed and understand
that it pretty much reflects across the speed axis into the region of negative
(that is, applied) torque, allowing the motor to act as a generator.

I plan to use AC excitation but don't understand how to connect the load so
that the generator will drive it. Certainly the impedance of the wall socket is
very low, while the impedance of my onboard sine wave inverter, which supplies
AC excitation to the motor, may be higher or lower. In any case, I suspect the
impedance of this impedance protected motor to be rather high.

The proposed loads are two: one, a highly efficient white LED signal light
donated by John Viselli at Dialight for this R&D project, and two, an even more
efficient high pressure sodium fixture to be purchased at The Home Depot or
from Grainger when the LED light goes on line.

The LED light is 8W, and is entirely suitable for use as a road headlight, with
its trapezoidal beam pattern, sealed construction, and easy mounting into a
fairing. It can be mounted directly to the motor, for now, it is so light. I
have fabricated one such adapter already, and two model adapters of foam to
carry the "guts" of a simlar light, a green LED traffic light. These weigh
grams.

The sodium fixture is a little heavier, but not too bad. It is rated 35 W and
is entirely suitable for navigating difficult terrain at night, at high speeds.
It's a flood light.

I finished the plastic shell for the road wheel powered DC motor/generator the
other day. This generator will power the inverter, and the inverter will excite
the AC generator. Rider power will be transormed by the generator into AC power
to power the lamp. That's a jump from 60 Hz mechanical power to 60 Hz AC, then
around 33 octaves to visible light. No, this isn't a perpetual motion machine
or a dynamic brake. The AC motor is being used as a generator with AC
excitation supplied by the inverter, which is in turn supplied by the 30 VDC,
12 A stall motor/generator. There's very little drag in the mechanicals. There
are losses, though. Compared to a CVT hub, these losses are acceptable. That
is, ridability has not been affected. I road with the AC generator on chain
drive for several miles the other day. I didn't generate any power but losses
were low.

So how do I establish load sharing between the inverter and AC generator?

That is, how do I excite the generator and seamlessly make use of the generated
power?

The only way I can think of that doesn't use great big transformers is
to use a 4-quadrant inverter so that power flowing into the inverter
will appear as DC current coming _out_.

Then load share between the DC generator and the light.

 

[colin]

In an earlier thread, "Inpedance Protection of Ceiling Fan Motor" (sic), and
other threads here and in other newsgroups, I have considered the possiblity of
using a split phase capacitor run AC motor as a generator.

I have assembled the motor to my bicycle and it runs the cranks just fine. I
don't intend to build an AC motor powered bicycle with it. After all, what
would you do when the required extension cord pulled out of the wall? It is
useful to have an AC motor on a bicycle. When in the shop for maintenance, all
one need do is plug in the motor and spend a few minutes tuning the
transmission for maximum shift efficiency, saving much time.

From my EET 350 (Fundamentals of Electrical Technology) textbook, "Introduction
to Electricity, Electronics, and Electromagnetism", I see that the torque curve
as a function of speed is sharply sloped near synchronous speed and understand
that it pretty much reflects across the speed axis into the region of negative
(that is, applied) torque, allowing the motor to act as a generator.

I plan to use AC excitation but don't understand how to connect the load so
that the generator will drive it. Certainly the impedance of the wall socket is
very low, while the impedance of my onboard sine wave inverter, which supplies
AC excitation to the motor, may be higher or lower. In any case, I suspect the
impedance of this impedance protected motor to be rather high.

The proposed loads are two: one, a highly efficient white LED signal light
donated by John Viselli at Dialight for this R&D project, and two, an even more
efficient high pressure sodium fixture to be purchased at The Home Depot or
from Grainger when the LED light goes on line.

The LED light is 8W, and is entirely suitable for use as a road headlight, with
its trapezoidal beam pattern, sealed construction, and easy mounting into a
fairing. It can be mounted directly to the motor, for now, it is so light. I
have fabricated one such adapter already, and two model adapters of foam to
carry the "guts" of a simlar light, a green LED traffic light. These weigh
grams.

The sodium fixture is a little heavier, but not too bad. It is rated 35 W and
is entirely suitable for navigating difficult terrain at night, at high speeds.
It's a flood light.

I finished the plastic shell for the road wheel powered DC motor/generator the
other day. This generator will power the inverter, and the inverter will excite
the AC generator. Rider power will be transormed by the generator into AC power
to power the lamp. That's a jump from 60 Hz mechanical power to 60 Hz AC, then
around 33 octaves to visible light. No, this isn't a perpetual motion machine
or a dynamic brake. The AC motor is being used as a generator with AC
excitation supplied by the inverter, which is in turn supplied by the 30 VDC,
12 A stall motor/generator. There's very little drag in the mechanicals. There
are losses, though. Compared to a CVT hub, these losses are acceptable. That
is, ridability has not been affected. I road with the AC generator on chain
drive for several miles the other day. I didn't generate any power but losses
were low.

So how do I establish load sharing between the inverter and AC generator?

That is, how do I excite the generator and seamlessly make use of the generated
power?

As was said before, i dont think an induction motor is at all suitable for a
stand alone generator, its ok if you have a AC supply, but if you want to
power a load independantly you need an exciting voltage supply wich is not
only almost powerfull enough in itself to power the load anyway but cope
with corecting the power factor of the generator, ie produced curent is not
in phase with voltage. its all very messy tbh.

Im sure you would be better off just using one DC motor/generator that was
big enough, and use an inverter for 60hz power if needed. maybe get an old
car dc dynamo? ive seen some powerfull permanent magnet motors used in
washing machines, also maybe you could power the sodium lamp from DC using a
converter/inverter to drive the lamp directly.

if youve got some realy strong magnets lying around maybe you could take the
induction motor apart and put them in the rotor, might make an ok generator
then although probably not a very good motor, as stall curent might well
demagnetize the magnets.

Colin =^.^=

 

[Terry Given]

possiblity of


It is


socket is



As was said before, i dont think an induction motor is at all suitable for a
stand alone generator, its ok if you have a AC supply, but if you want to
power a load independantly you need an exciting voltage supply wich is not
only almost powerfull enough in itself to power the load anyway but cope
with corecting the power factor of the generator, ie produced curent is not
in phase with voltage. its all very messy tbh.

thats not true. so-called "self-excited induction generators" have been
around for years, and they work - for a 3ph SCIM just slap a star of
caps across the output, and spin the shaft. Remanent flux in the iron of
the machine acts like an (albeit weak) permanent magnet, generating a
small stator voltage, enabling the resultant stator current to generate
rotor flux, thereby bootstrapping the whole machine. cap selection is of
course rather important.

IEE trans. industry apps. has published dozens (prob. hundreds) of
papers over the last few years on SEIGs. Just recently they published a
couple of papers on drives for split-phase IMs - with an active drive,
no caps are required.

Frede Blaabjerg, F. Lungeneanu, K. Skaug & M. Tonnes wrote an article in
the July/August 2004 IEE trans industry apps magazine "Two-phase
induction motor drives" which has a whole bunch of really good info on
TPIMs. they have a decent reference list at the end of the articel.

As for generator power factor etc - the "generator" has some finite
(inductive) output impedance - often up to 30%. choose the IM wisely
grasshopper...

Im sure you would be better off just using one DC motor/generator that was
big enough, and use an inverter for 60hz power if needed. maybe get an old
car dc dynamo? ive seen some powerfull permanent magnet motors used in
washing machines, also maybe you could power the sodium lamp from DC using a
converter/inverter to drive the lamp directly.

if youve got some realy strong magnets lying around maybe you could take the
induction motor apart and put them in the rotor, might make an ok generator
then although probably not a very good motor, as stall curent might well
demagnetize the magnets.

people who build their own motors soon discover that building a reliable
motor isnt that easy.

Colin =^.^=

cheers
Terry

 

[colin]

thats not true. so-called "self-excited induction generators" have been
around for years, and they work - for a 3ph SCIM just slap a star of
caps across the output, and spin the shaft. Remanent flux in the iron of
the machine acts like an (albeit weak) permanent magnet, generating a
small stator voltage, enabling the resultant stator current to generate
rotor flux, thereby bootstrapping the whole machine. cap selection is of
course rather important.

Interesting, how well does this lend itself to a single phase capacitor
start induction motor like the one the OP has already incorporated into his
bike?

Out of interest I just tried with a small fan motor and range of caps and
spun the motor up with a dc motor with a rubber wheel, with no cap I got
1vac , at best the capacitor increased the output to about 1.5vac, with a
bigger capacitor the output fell. i suspect that with a single phase motor
this isnt going to do anything, and i suspect the only reason the output
increased was due to resonance. maybe with a capacitor start motor you can
use the second winding although i tried this with a large motor and it wasnt
very sucesfull i can only spin this by hand.

As for generator power factor etc - the "generator" has some finite
(inductive) output impedance - often up to 30%. choose the IM wisely
grasshopper...

unfortunatly chioce is limited here (to 1) and its impedance protected so is
designed to have enough inductance to limit the curent at 110v to a safe
value at stall.

people who build their own motors soon discover that building a reliable
motor isnt that easy.

true, i have built quite a few mainly for experiments with micro
stepping/switched reluctance etc, but have mainly used existing motor cages
and bearings etc and just replaced the various magnetic bits, but wasnt
meant as a totaly serious sugestion, just brainstorming, but thinking about
it and looking at the pictures, if u had some reasonably sized dc motors and
took the magnets out and cut slots in the armature ...as i see you already
have it in bits, it might well outperform other forms of excitation using
this motor, but the th OP idea of being able to easily replace the fan motor
becomes untenable.

Colin =^.^=

 

[Doug Goncz]

Today I connected the main phase to AC and spun the rotor. It continued to spin
while energized.

Later, I will try energizing the split phase with AC, driving the shaft with
the pedals and taking AC from the main phase.

Thanks to knight in shining armor Terry.

Off to the library or to ieee.org....


Yours,
Doug Goncz ( ftp://users.aol.com/DGoncz/incoming )
Student member SAE for one year.
I love: Dona, Jeff, Kim, Mom, Neelix, Tasha, and Teri, alphabetically.
I drive: A double-step Thunderbolt with 657% range.

 

[Doug Goncz]

Dear Terry,

Would you think the Surplus Center's #10-1134 225 rpm split phase capacitor run
impedance protected ceiling fan motor would make a decent human powered
generator?

http://surpluscenter.com/item.asp?UID=2004101315154496&catname=&qty=1&item
=10-1134

Oh, dear, that link looks long. Is it breaking in any reader's reader?

I have had the shaft of this motor machined to accept my standard 8 tooth
pinion for bicycle chain, the same one I use on the DC motor/generator. It is
mounted over the cranks, near them, and chain wrap is low, only some 30
degrees, to reduce pedaling drag and improve chain retention over bumps. The
drive cog is 51 teeth, matching the custom gearing on the right, giving a motor
speed near 225 rpm, with variations in peadling speed right about the human
range of, for non-racers like me, 40-90 rpm producing proportional changes in
motor speed.

I can try two things.

One, run an inverter from the road wheel driven DC motor generator, and excite
one phase of the motor, drawing power from the other when the cranks are
turned, possibly, through coupling, even when they are not turned.

Two, use the DC supply to hit both phases of the motor with the secondary
winding's phase shift capacitor in place, in order to excite the rotor, and
then open the DC circuit, continue pedaling, and place the load on line.
Lindsay Technical Books has a publication, Alternator Secrets, that says this
will work. The author claims a split phase motor with phase shift capacitor is
suited to generator operation.

Googling

"self-excited induction generators"

From: Terry Given [email protected]

produces 185 hits, and you have my deepest thanks for naming this beast.

IEE trans. industry apps. has published dozens (prob. hundreds) of
papers over the last few years on SEIGs. Just recently they published a
couple of papers on drives for split-phase IMs - with an active drive,
no caps are required.

Hot on the trail....

As for generator power factor etc - the "generator" has some finite
(inductive) output impedance - often up to 30%. choose the IM wisely
grasshopper...

Yes, this impedance protected motor is perfectly shaped for bicycle
application, but has high impedance. I am going with the shape to start,
finding key components like that is my business, and making them work my
profession.

But hey, anybody, save me some time here if you can. If it can't work, say why.

people who build their own motors soon discover that building a reliable
motor isnt that easy.

Yes, I find the one-moving part plus bearings idea of this motor suitable for
my intended applciation. Much less complicated than the DC generator it is to
replace.


Yours,
Doug Goncz ( ftp://users.aol.com/DGoncz/incoming )
Student member SAE for one year.
I love: Dona, Jeff, Kim, Mom, Neelix, Tasha, and Teri, alphabetically.
I drive: A double-step Thunderbolt with 657% range.

 

[Doug Goncz]

Hello all. I have read Google: "self-excited induction generator" to about 10%.

I found:

Electrical Construction and Maintenance

Guidelines for engine-generator application designs.


by Lawrie, Robert J. | May 01 '96


on Keep Media.

----------------------------------------------------

Induction generator

The construction of an induction generator is essentially the same as that of
an induction motor: Both have a squirrel-cage rotor and wound stator. When this
machine is driven above its designed synchronous speed, it becomes a generator;
at less than synchronous speed, it functions as a motor. Because the induction
generator does not have an exciter, it must operate in parallel with the
utility. This outside power source provides the reactive power for generator
operation. Also, its frequency is automatically locked in with the utility.

An induction generator is a popular choice for use when designing cogeneration
systems, where it will operate in parallel with the utility. This type of
generator offers certain advantages over a synchronous generator. For example,
voltage and frequency are controlled by the utility; thus voltage and frequency
regulators are not required. In addition, the generator construction offers
high reliability and little maintenance. Also, a minimum of protective relays
and controls are required. Its major disadvantage is that it normally cannot
operate alone as a standby/emergency generator in such an application.

---------------------------------------------------


Yours,
Doug Goncz ( ftp://users.aol.com/DGoncz/incoming )
Student member SAE for one year.
I love: Dona, Jeff, Kim, Mom, Neelix, Tasha, and Teri, alphabetically.
I drive: A double-step Thunderbolt with 657% range.

 

[Tony Williams]

Hello all. I have read Google: "self-excited induction
generator" to about 10%.

Induction generator

[snip]

There was a thread here (a year or so ago) that described
an interesting application of that "asynchronous generator".

It was about a conveying system, (in Australia?), that
carried ore for miles, up and down hills, but overall it
was downhill.

The whole system was driven by induction motors, which took
megawatts to get the ore moving, but once everything was up
to speed, the conveyer drove the motors. The motors then
became generators, and nicely acted as speed limiters for
the conveying system.

 

[Rich Grise]

Hello all. I have read Google: "self-excited induction
generator" to about 10%.

Induction generator

[snip]

There was a thread here (a year or so ago) that described
an interesting application of that "asynchronous generator".

It was about a conveying system, (in Australia?), that
carried ore for miles, up and down hills, but overall it
was downhill.

The whole system was driven by induction motors, which took
megawatts to get the ore moving, but once everything was up
to speed, the conveyer drove the motors. The motors then
became generators, and nicely acted as speed limiters for
the conveying system.

And if they let the intake end go empty for too long, it breaks
the siphon, right? ;-)

A two-mile, electric rock siphon. What will they think of next?

Cheers!
Rich

 

[Tony Williams]

And if they let the intake end go empty for too long, it breaks
the siphon, right? ;-)

I think if the 'syphon' reduced then the induction
motors would automatically slip back to motoring.

 

[Rich Grise]

I think if the 'syphon' reduced then the induction
motors would automatically slip back to motoring.

For some reason, that brings to mind the sound of a carny ride
motor lugging when the ride starts or pulls G's & like that. ;-)

Cheers!
Rich

 

[Terry Given]

Hello all. I have read Google: "self-excited induction generator" to about 10%.

I found:

Electrical Construction and Maintenance

Guidelines for engine-generator application designs.


by Lawrie, Robert J. | May 01 '96


on Keep Media.

----------------------------------------------------

Induction generator

The construction of an induction generator is essentially the same as that of
an induction motor: Both have a squirrel-cage rotor and wound stator. When this
machine is driven above its designed synchronous speed, it becomes a generator;
at less than synchronous speed, it functions as a motor. Because the induction
generator does not have an exciter, it must operate in parallel with the
utility. This outside power source provides the reactive power for generator
operation. Also, its frequency is automatically locked in with the utility.

An induction generator is a popular choice for use when designing cogeneration
systems, where it will operate in parallel with the utility. This type of
generator offers certain advantages over a synchronous generator. For example,
voltage and frequency are controlled by the utility; thus voltage and frequency
regulators are not required. In addition, the generator construction offers
high reliability and little maintenance. Also, a minimum of protective relays
and controls are required. Its major disadvantage is that it normally cannot
operate alone as a standby/emergency generator in such an application.

---------------------------------------------------


Yours,
Doug Goncz ( ftp://users.aol.com/DGoncz/incoming )
Student member SAE for one year.
I love: Dona, Jeff, Kim, Mom, Neelix, Tasha, and Teri, alphabetically.
I drive: A double-step Thunderbolt with 657% range.

yep. And if you dont have a grid, the add-on caps provide the reactive
current path.

Cheers
Terry