Matching to the impedance of an alternator.

On Sun, 15 Jan 2012 03:10:52 GMT, Ralph Barone
address_is_at_invalid.invalid> wrote:

John Larkin <jjlarkin_at_highNOTlandTHIStechnologyPART.com> wrote:
On Sat, 14 Jan 2012 16:06:37 -0700, Jim Thompson
To-Email-Use-The-Envelope-Icon_at_On-My-Web-Site.com> wrote:

On Sat, 14 Jan 2012 13:48:05 -0800, John Larkin
jjlarkin_at_highNOTlandTHIStechnologyPART.com> wrote:

On Sat, 14 Jan 2012 11:39:04 -0800 (PST), whit3rd <whit3rd_at_gmail.com
wrote:

On Monday, January 9, 2012 9:30:17 PM UTC-8, josephkk wrote:

[about shorting a generator's terminals]
... remember
that current and voltage are out of phase in capacitors or inductors
connected across line voltage don't you? (No real power but plenty of
VAR.)

Return to considering a normal generator / alternator / dynamo operating
into a short circuit. Does a current flow? What is the phase between the
current and the voltage induced in the winding? Why?

The generator, operating into a short, cogs. That is, the feel
of the rotor as you turn it is alternately a spring-like retarding force
and then a spring-like advancing force. A pedaling
operator will feel a vibration, more than a rotation resistance.

Right. The force curve on the magnet poles is almost 90 degrees from
the velocity curve, so the torque is sinusoidal and averages close to
zero. Conservation of Energy survives intact. If the coil has a
substantially resistive load, the electrical and mechanical phase
angles shift, real power is dissipated, and it takes real torque to do
that.


In the case of a bicycle-type generator, power efficiency is TERRIBLE
and you cannot usefully apply an external short to the unit, because
there's significant resistance internal to the windings.

Well, efficiency is always zero into a shorted load. But if the
open-circuit voltage is, say, 30 volts RMS, and it's driving a lamp at
6 volts, it's running almost shorted. I conjecture that driving torque
increases from a dead short to a lamp-like (low voltage) load. Torque
will probably peak around the resistive load that drops the output
voltage to half its open-circuit value, because that's about when the
most power is generated.


If any serious attempt is to be made at power efficiency in a
bicycle-powered generator, it'll be with an automotive style
generator, using a controlled field winding and low-impedance
current-output windings. The idea of using permanent magnet
dynamos works well for reliability and ease of manufacture,
but isn't good for efficient charging of a battery. I'm dubious that
electronic regulation, on this small scale, will improve matters.

Lots of motorcycles and aircraft generators use PM fields, and have
regulators. It's common to short the output with a thyristor to
regulate.

John


Blah! Blah! Blah! Schadenfreude, Schadenfreude, dork, dork, dork ;-)

Schematic release at maximum Schadenfreude ;-)


You've lost your mind; second childhood for sure.

One symptom is that you can't understand electronics any more.

John

Jim and John, please make some attempt to act your age (which is
embarrassing for me to say, since I suspect I'm younger than either of
you).

I'm just over a month away from celebrating my 18th Birthday

...Jim Thompson

Jim Thompson <To-Email-Use-The-Envelope-Icon_at_On-My-Web-Site.com> wrote:
On Sun, 15 Jan 2012 03:10:52 GMT, Ralph Barone
address_is_at_invalid.invalid> wrote:

John Larkin <jjlarkin_at_highNOTlandTHIStechnologyPART.com> wrote:
On Sat, 14 Jan 2012 16:06:37 -0700, Jim Thompson
To-Email-Use-The-Envelope-Icon_at_On-My-Web-Site.com> wrote:

On Sat, 14 Jan 2012 13:48:05 -0800, John Larkin
jjlarkin_at_highNOTlandTHIStechnologyPART.com> wrote:

On Sat, 14 Jan 2012 11:39:04 -0800 (PST), whit3rd <whit3rd_at_gmail.com
wrote:

On Monday, January 9, 2012 9:30:17 PM UTC-8, josephkk wrote:

[about shorting a generator's terminals]
... remember
that current and voltage are out of phase in capacitors or inductors
connected across line voltage don't you? (No real power but plenty of
VAR.)

Return to considering a normal generator / alternator / dynamo operating
into a short circuit. Does a current flow? What is the phase between the
current and the voltage induced in the winding? Why?

The generator, operating into a short, cogs. That is, the feel
of the rotor as you turn it is alternately a spring-like retarding force
and then a spring-like advancing force. A pedaling
operator will feel a vibration, more than a rotation resistance.

Right. The force curve on the magnet poles is almost 90 degrees from
the velocity curve, so the torque is sinusoidal and averages close to
zero. Conservation of Energy survives intact. If the coil has a
substantially resistive load, the electrical and mechanical phase
angles shift, real power is dissipated, and it takes real torque to do
that.


In the case of a bicycle-type generator, power efficiency is TERRIBLE
and you cannot usefully apply an external short to the unit, because
there's significant resistance internal to the windings.

Well, efficiency is always zero into a shorted load. But if the
open-circuit voltage is, say, 30 volts RMS, and it's driving a lamp at
6 volts, it's running almost shorted. I conjecture that driving torque
increases from a dead short to a lamp-like (low voltage) load. Torque
will probably peak around the resistive load that drops the output
voltage to half its open-circuit value, because that's about when the
most power is generated.


If any serious attempt is to be made at power efficiency in a
bicycle-powered generator, it'll be with an automotive style
generator, using a controlled field winding and low-impedance
current-output windings. The idea of using permanent magnet
dynamos works well for reliability and ease of manufacture,
but isn't good for efficient charging of a battery. I'm dubious that
electronic regulation, on this small scale, will improve matters.

Lots of motorcycles and aircraft generators use PM fields, and have
regulators. It's common to short the output with a thyristor to
regulate.

John


Blah! Blah! Blah! Schadenfreude, Schadenfreude, dork, dork, dork ;-)

Schematic release at maximum Schadenfreude ;-)


You've lost your mind; second childhood for sure.

One symptom is that you can't understand electronics any more.

John

Jim and John, please make some attempt to act your age (which is
embarrassing for me to say, since I suspect I'm younger than either of
you).

I'm just over a month away from celebrating my 18th Birthday

...Jim Thompson

And if I was also born in a leap year, I would be 11. That wouldn't
necessarily give me license to act 11.

Jim Thompson <To-Email-Use-The-Envelope-Icon_at_On-My-Web-Site.com> wrote:
On Sun, 15 Jan 2012 15:36:30 -0600, John Fields
jfields_at_austininstruments.com> wrote:

[snip]

---
If JT has the answer to your question, and you want that answer, why
would you not care to ask for, pay homage to, and graciously accept
his word instead of biting off your nose to spite your face?

I also ran the dynamo model into a _perfect_ auto-transformer, varying
inductance all the way up to 100H, hunting for success. As I posted,
the results look very much like a power-limited source.

'Tis a shame they built it that way to avoid any electronics.

Larkin will sink his own boat, I don't have to do it. He can keep
lying, but I have the whole thread in time sequence.

...Jim Thompson

The excess inductance was a good idea when bicycle dynamos were invented,
but I agree that it just gets in the way now. It would be nice to design a
"proper" dynamo then have a small box of electronics that takes care of
voltage regulation and power management. You could then have separate
outputs for accessory power, lighting power and battery charging, each with
their own power management algorithm.

On Mon, 16 Jan 2012 03:02:43 GMT, Ralph Barone
address_is_at_invalid.invalid> wrote:

Jim Thompson <To-Email-Use-The-Envelope-Icon_at_On-My-Web-Site.com> wrote:
On Sun, 15 Jan 2012 03:10:52 GMT, Ralph Barone
address_is_at_invalid.invalid> wrote:

John Larkin <jjlarkin_at_highNOTlandTHIStechnologyPART.com> wrote:
On Sat, 14 Jan 2012 16:06:37 -0700, Jim Thompson
To-Email-Use-The-Envelope-Icon_at_On-My-Web-Site.com> wrote:

On Sat, 14 Jan 2012 13:48:05 -0800, John Larkin
jjlarkin_at_highNOTlandTHIStechnologyPART.com> wrote:

On Sat, 14 Jan 2012 11:39:04 -0800 (PST), whit3rd
whit3rd_at_gmail.com
wrote:

On Monday, January 9, 2012 9:30:17 PM UTC-8, josephkk wrote:

[about shorting a generator's terminals]
... remember
that current and voltage are out of phase in capacitors or
inductors
connected across line voltage don't you? (No real power but
plenty of
VAR.)

Return to considering a normal generator / alternator / dynamo
operating
into a short circuit. Does a current flow? What is the phase
between the
current and the voltage induced in the winding? Why?

The generator, operating into a short, cogs. That is, the feel
of the rotor as you turn it is alternately a spring-like retarding
force
and then a spring-like advancing force. A pedaling
operator will feel a vibration, more than a rotation resistance.

Right. The force curve on the magnet poles is almost 90 degrees from
the velocity curve, so the torque is sinusoidal and averages close
to
zero. Conservation of Energy survives intact. If the coil has a
substantially resistive load, the electrical and mechanical phase
angles shift, real power is dissipated, and it takes real torque to
do
that.


In the case of a bicycle-type generator, power efficiency is
TERRIBLE
and you cannot usefully apply an external short to the unit,
because
there's significant resistance internal to the windings.

Well, efficiency is always zero into a shorted load. But if the
open-circuit voltage is, say, 30 volts RMS, and it's driving a lamp
at
6 volts, it's running almost shorted. I conjecture that driving
torque
increases from a dead short to a lamp-like (low voltage) load.
Torque
will probably peak around the resistive load that drops the output
voltage to half its open-circuit value, because that's about when
the
most power is generated.


If any serious attempt is to be made at power efficiency in a
bicycle-powered generator, it'll be with an automotive style
generator, using a controlled field winding and low-impedance
current-output windings. The idea of using permanent magnet
dynamos works well for reliability and ease of manufacture,
but isn't good for efficient charging of a battery. I'm dubious
that
electronic regulation, on this small scale, will improve matters.

Lots of motorcycles and aircraft generators use PM fields, and have
regulators. It's common to short the output with a thyristor to
regulate.

John


Blah! Blah! Blah! Schadenfreude, Schadenfreude, dork, dork, dork ;-)

Schematic release at maximum Schadenfreude ;-)


You've lost your mind; second childhood for sure.

One symptom is that you can't understand electronics any more.

John

Jim and John, please make some attempt to act your age (which is
embarrassing for me to say, since I suspect I'm younger than either of
you).

I'm just over a month away from celebrating my 18th Birthday :-)

...Jim Thompson

And if I was also born in a leap year, I would be 11. That wouldn't
necessarily give me license to act 11.

I'm not.

On Mon, 16 Jan 2012 03:02:42 GMT, Ralph Barone
address_is_at_invalid.invalid> wrote:

Jim Thompson <To-Email-Use-The-Envelope-Icon_at_On-My-Web-Site.com> wrote:
On Sun, 15 Jan 2012 15:36:30 -0600, John Fields
jfields_at_austininstruments.com> wrote:

[snip]

---
If JT has the answer to your question, and you want that answer, why
would you not care to ask for, pay homage to, and graciously accept
his word instead of biting off your nose to spite your face?

I also ran the dynamo model into a _perfect_ auto-transformer, varying
inductance all the way up to 100H, hunting for success. As I posted,
the results look very much like a power-limited source.

'Tis a shame they built it that way to avoid any electronics.

Larkin will sink his own boat, I don't have to do it. He can keep
lying, but I have the whole thread in time sequence.

...Jim Thompson

The excess inductance was a good idea when bicycle dynamos were invented,
but I agree that it just gets in the way now. It would be nice to design a
"proper" dynamo then have a small box of electronics that takes care of
voltage regulation and power management. You could then have separate
outputs for accessory power, lighting power and battery charging, each with
their own power management algorithm.

Indeed! It would be so easy!

...Jim Thompson

Jim and John, please make some attempt to act your age (which is
embarrassing for me to say, since I suspect I'm younger than either of
you).

I'm just over a month away from celebrating my 18th Birthday

...Jim Thompson

And if I was also born in a leap year, I would be 11. That wouldn't
necessarily give me license to act 11.

I'm not.

...Jim Thompson

Jim Thompson <To-Email-Use-The-Envelope-Icon_at_On-My-Web-Site.com> wrote:
On Mon, 16 Jan 2012 03:02:42 GMT, Ralph Barone
address_is_at_invalid.invalid> wrote:

Jim Thompson <To-Email-Use-The-Envelope-Icon_at_On-My-Web-Site.com> wrote:
On Sun, 15 Jan 2012 15:36:30 -0600, John Fields
jfields_at_austininstruments.com> wrote:

[snip]

---
If JT has the answer to your question, and you want that answer, why
would you not care to ask for, pay homage to, and graciously accept
his word instead of biting off your nose to spite your face?

I also ran the dynamo model into a _perfect_ auto-transformer, varying
inductance all the way up to 100H, hunting for success. As I posted,
the results look very much like a power-limited source.

'Tis a shame they built it that way to avoid any electronics.

Larkin will sink his own boat, I don't have to do it. He can keep
lying, but I have the whole thread in time sequence.

...Jim Thompson

The excess inductance was a good idea when bicycle dynamos were invented,
but I agree that it just gets in the way now. It would be nice to design a
"proper" dynamo then have a small box of electronics that takes care of
voltage regulation and power management. You could then have separate
outputs for accessory power, lighting power and battery charging, each with
their own power management algorithm.

Indeed! It would be so easy!

...Jim Thompson

For some people... I'm far enough away from electronics design (and more
importantly, mass production electronics assembly) that my best bet is for
one of you folks to design and market said device.

The real snag is that the hub dynamo, if the model paper presented by
Marcel is correct, is actually _almost_ a perfect constant POWER
source... sure acts like that under a lamp load, see:

Message-ID: <f4b16699qk6hi6u4lpthe7acbgi2j1r8ke_at_4ax.com

for details.

But I have suspicions about the accuracy of the model. If someone
will send me such a hub dynamo I'll characterize it as a _non-linear_
device, which is what I suspect it really is... not a linear lump as
presently represented.

On Sun, 15 Jan 2012 15:36:30 -0600, John Fields
jfields_at_austininstruments.com> wrote:

[snip]

---
If JT has the answer to your question, and you want that answer, why
would you not care to ask for, pay homage to, and graciously accept
his word instead of biting off your nose to spite your face?

I also ran the dynamo model into a _perfect_ auto-transformer, varying
inductance all the way up to 100H, hunting for success. As I posted,
the results look very much like a power-limited source.

'Tis a shame they built it that way to avoid any electronics.

Larkin will sink his own boat, I don't have to do it. He can keep
lying, but I have the whole thread in time sequence.

The excess inductance was a good idea when bicycle dynamos were invented,
but I agree that it just gets in the way now. It would be nice to design a
"proper" dynamo then have a small box of electronics that takes care of
voltage regulation and power management. You could then have separate
outputs for accessory power, lighting power and battery charging, each with
their own power management algorithm.

The excess inductance was a good idea when bicycle dynamos were invented,
but I agree that it just gets in the way now. It would be nice to design a
"proper" dynamo then have a small box of electronics that takes care of
voltage regulation and power management. You could then have separate
outputs for accessory power, lighting power and battery charging, each with
their own power management algorithm.

Indeed! It would be so easy!

Equivalent? I'm discussing electronics and he's making goofy noises.

On 2012-01-14, Jim Thompson <To-Email-Use-The-Envelope-Icon_at_On-My-Web-Site.com> wrote:

The real snag is that the hub dynamo, if the model paper presented by
Marcel is correct, is actually _almost_ a perfect constant POWER
source... sure acts like that under a lamp load, see:

Message-ID: <f4b16699qk6hi6u4lpthe7acbgi2j1r8ke_at_4ax.com

for details.

But I have suspicions about the accuracy of the model. If someone
will send me such a hub dynamo I'll characterize it as a _non-linear_
device, which is what I suspect it really is... not a linear lump as
presently represented.

can't be constant power:
peopole run two headights in series off them for twice the illumination.

hmm, series:

use a relay to put the battery in series with the lamp when there's
enough speed (use a diode pump driven by the altenator to power the relay)
short the bottom diode when there's enough charge.