| Topic: |
Science > Physics |
| User: |
"RichD" |
| Date: |
17 Dec 2006 06:02:39 AM |
| Object: |
efficiency of regenerative braking? |
What is the efficiency of regenerative braking in electric
vehicles? How much kinetic energy is recovered?
--
Rich
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| User: "werty" |
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| Title: Re: efficiency of regenerative braking? |
20 Dec 2006 10:55:53 PM |
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Batteries require at least 160 % to recharge . If you get 100 % , it
will take at least 1.6 times that energy to charge the batt' .
Electric Braking wears few parts , so its a good idea . But you must
apply
current to a rotor to make magnetic flux , to produce amperage in the
stator .
But it does work well , as our cars have alternators that are
efficient ,
taking only 20 watts rotor for 700 watts at the stator .
They have a wide speed range . Car alternators will work well
between 1000 and 10,000 RPM . I dont like 10,000 RPM for the
wear/tear
on ball bearings/needle bearings . I prefer less than 6000 .
First pick a good motor , then design braking .
BTW Wind generators can use car alt' well , keep the output in 3 phase
and above 40 volts til it reaches the batteries , then switch mode
"buck"
regulate to charge battteries .
And SCR's can be used to modify the output to run 60hz appliances .
3 phase to single phase , by switching the 3 windings at the proper
time . U need 6 SCR's for a Delta wound .
BTW , OT .. fully discharge a NimH battery ? Nikon ( S-4 digi-cam)
says
you must fully discharge their batteries occasionaly ..
What do you think ? Lead Acid batteries , sulfate , but NimH are
opposite
electrolyte , its alkaline . Is there a similar effect to sulfation
in hydroxide
in a dry AA NimH cell ?
RichD wrote:
What is the efficiency of regenerative braking in electric
vehicles? How much kinetic energy is recovered?
--
Rich
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| User: "" |
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| Title: Re: efficiency of regenerative braking? |
21 Dec 2006 06:55:22 PM |
|
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werty wrote:
Batteries require at least 160 % to recharge . If you get 100 % , it
will take at least 1.6 times that energy to charge the batt' .
Electric Braking wears few parts , so its a good idea . But you must
apply
current to a rotor to make magnetic flux , to produce amperage in the
stator .
But it does work well , as our cars have alternators that are
efficient ,
taking only 20 watts rotor for 700 watts at the stator .
They have a wide speed range . Car alternators will work well
between 1000 and 10,000 RPM . I dont like 10,000 RPM for the
wear/tear
on ball bearings/needle bearings . I prefer less than 6000 .
First pick a good motor , then design braking .
BTW Wind generators can use car alt' well , keep the output in 3 phase
and above 40 volts til it reaches the batteries , then switch mode
"buck"
regulate to charge battteries .
And SCR's can be used to modify the output to run 60hz appliances .
3 phase to single phase , by switching the 3 windings at the proper
time . U need 6 SCR's for a Delta wound .
BTW , OT .. fully discharge a NimH battery ? Nikon ( S-4 digi-cam)
says
you must fully discharge their batteries occasionaly ..
What do you think ? Lead Acid batteries , sulfate , but NimH are
opposite
electrolyte , its alkaline
Lead Acid batteries are always the wrong choice
unless you enjoy being in permanent debt to
the government.
Since the primary attraction of wind energy is that it
can reduce the cost of power meters to zero,
.. Is there a similar effect to sulfation
in hydroxide
in a dry AA NimH cell ?
RichD wrote:
What is the efficiency of regenerative braking in electric
vehicles? How much kinetic energy is recovered?
--
Rich
.
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| User: "Sorcerer" |
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| Title: Re: efficiency of regenerative braking? |
17 Dec 2006 06:33:34 AM |
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"RichD" <r_delaney2001@yahoo.com> wrote in message =
news:1166356959.797604.149450@j72g2000cwa.googlegroups.com...
| What is the efficiency of regenerative braking in electric
| vehicles? =20
High.
How much kinetic energy is recovered?
Almost all. Losses are in heating only, brakes heat a lot,=20
cables, motors and batteries very little.
.
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| User: "Bret Cahill" |
|
| Title: Re: efficiency of regenerative braking? |
17 Dec 2006 07:42:02 AM |
|
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| What is the efficiency of regenerative braking in electric
| vehicles?
High.
Isn't regenerative braking just the DC traction motors running
backwards?
An alternator that worked over a broad rpm range touted 70% efficiency
in a recent patent.
It would be interesting if they could beat that.
Bret Cahill
.
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| User: "Comboverfish" |
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| Title: Re: efficiency of regenerative braking? |
17 Dec 2006 12:03:23 PM |
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Bret Cahill wrote:
Isn't regenerative braking just the DC traction motors running
backwards?
Simply put, yes. In the current hybrid system common to several
manufactures, there are two motors in the transaxle. The larger motor
is designated for providing the majority of motive torque. The smaller
motor is used as a "starter" as it is attached directly to the engine
output, and also functions to react to the larger motor to effectively
create infinitely variable output gearing ("shifting"). To get to the
point, both motors are either energized or tapped by the HV ECU to
create torque or recharge the HV battery, respectively.
The motors don't run "backwards" but are used in reverse current flow
to charge the HV battery via an ac/dc converter that is managed by the
HV ECU. Regeneration occurs whenever the various ECUs communicate to
the HV ECU that charging is the correct strategy, be it during braking,
extended battery-only operation, startup, or whatever else I'm
forgetting.
Toyota MDT in MO
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| User: "Bret Cahill" |
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| Title: Re: efficiency of regenerative braking? |
17 Dec 2006 03:58:54 PM |
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Isn't regenerative braking just the DC traction motors running
backwards?
Simply put, yes. In the current hybrid system common to several
manufactures, there are two motors in the transaxle. The larger motor
is designated for providing the majority of motive torque. The smaller
motor is used as a "starter" as it is attached directly to the engine
output, and also functions to react to the larger motor to effectively
create infinitely variable output gearing ("shifting"). To get to the
point, both motors are either energized or tapped by the HV ECU to
create torque or recharge the HV battery, respectively.
What's the efficiency of the motor-generator in generator mode?
Is it the same at any rpm?
Bret Cahill
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| User: "Sorcerer" |
|
| Title: Re: efficiency of regenerative braking? |
17 Dec 2006 05:05:05 PM |
|
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"Bret Cahill" <BretCahill@aol.com> wrote in message =
news:1166392734.379584.125140@f1g2000cwa.googlegroups.com...
|> > Isn't regenerative braking just the DC traction motors running
| > > backwards?
|=20
| > Simply put, yes. In the current hybrid system common to several
| > manufactures, there are two motors in the transaxle. The larger =
motor
| > is designated for providing the majority of motive torque. The =
smaller
| > motor is used as a "starter" as it is attached directly to the =
engine
| > output, and also functions to react to the larger motor to =
effectively
| > create infinitely variable output gearing ("shifting"). To get to =
the
| > point, both motors are either energized or tapped by the HV ECU to
| > create torque or recharge the HV battery, respectively.
|=20
| What's the efficiency of the motor-generator in generator mode?
|=20
| Is it the same at any rpm?
Are you an engineer, stupid *****?
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| User: "Eeyore" |
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| Title: Re: efficiency of regenerative braking? |
17 Dec 2006 04:15:30 PM |
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Bret Cahill wrote:
What's the efficiency of the motor-generator in generator mode?
Probably in the same region as its efficiency as a motor but I have to say I'm
not totally sure.
Is it the same at any rpm?
The same principle applies.
Graham
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| User: "" |
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| Title: Re: efficiency of regenerative braking? |
17 Dec 2006 01:20:53 PM |
|
|
Bret Cahill wrote:
| What is the efficiency of regenerative braking in electric
| vehicles?
High.
Isn't regenerative braking just the DC traction motors running
backwards?
An alternator that worked over a broad rpm range touted 70% efficiency
in a recent patent.
It would be interesting if they could beat that.
Bret Cahill
As others here have pointed out, the motors don't run backwards, the
electrical current does. When DC electric motors run they also act as
generators. The voltage produced by the generator, sometimes called
the "back EMF" is proportional to the rpm. As the rpm goes up this
back EMF goes up and limits how high the rpm will go with no load on
the motor.
One way to make the motor charge the battery is to use a motor with
field windings and control the back EMF by controling the field
current. This same idea is used for the "voltage regulator" in many
automotive alternators.
Actually I think the most efficient systems in use today are varialbe
frequency AC systems. Many of the same ideas work and some are easier
to impliment with AC rather than DC.
Bruce
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| User: "" |
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| Title: Re: efficiency of regenerative braking? |
19 Dec 2006 03:28:51 AM |
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wrote:
Bret Cahill wrote:
| What is the efficiency of regenerative braking in electric
| vehicles?
High.
Isn't regenerative braking just the DC traction motors running
backwards?
An alternator that worked over a broad rpm range touted 70% efficiency
in a recent patent.
It would be interesting if they could beat that.
Bret Cahill
As others here have pointed out, the motors don't run backwards, the
electrical current does. When DC electric motors run they also act as
generators. The voltage produced by the generator, sometimes called
the "back EMF" is proportional to the rpm. As the rpm goes up this
back EMF goes up and limits how high the rpm will go with no load on
the motor.
One way to make the motor charge the battery is to use a motor with
field windings and control the back EMF by controling the field
current. This same idea is used for the "voltage regulator" in many
automotive alternators.
Actually I think the most efficient systems in use today are varialbe
frequency AC systems. Many of the same ideas work and some are easier
to impliment with AC rather than DC.
No they don't. Varible Frequency networks
are usually called servo motors, Which
are as often as not these days, being
replaced the computers, rather than electrical systems.
Wide area power distriubtion genarators
don't even work unless you have them synchronised
to about 60Hz +/- 0.1 Hz,
Bruce
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| User: "" |
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| Title: Re: efficiency of regenerative braking? |
19 Dec 2006 05:25:20 PM |
|
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wrote:
bsr3997@my-deja.com wrote:
Bret Cahill wrote:
| What is the efficiency of regenerative braking in electric
| vehicles?
High.
Isn't regenerative braking just the DC traction motors running
backwards?
An alternator that worked over a broad rpm range touted 70% efficiency
in a recent patent.
It would be interesting if they could beat that.
Bret Cahill
As others here have pointed out, the motors don't run backwards, the
electrical current does. When DC electric motors run they also act as
generators. The voltage produced by the generator, sometimes called
the "back EMF" is proportional to the rpm. As the rpm goes up this
back EMF goes up and limits how high the rpm will go with no load on
the motor.
One way to make the motor charge the battery is to use a motor with
field windings and control the back EMF by controling the field
current. This same idea is used for the "voltage regulator" in many
automotive alternators.
Actually I think the most efficient systems in use today are varialbe
frequency AC systems. Many of the same ideas work and some are easier
to impliment with AC rather than DC.
No they don't. Varible Frequency networks
are usually called servo motors, Which
are as often as not these days, being
replaced the computers, rather than electrical systems.
Wide area power distriubtion genarators
don't even work unless you have them synchronised
to about 60Hz +/- 0.1 Hz,
We weren't talking about networks, we were talking about motors and
controllers. There are controllers that can convert the DC from
batteries info AC and vary the frequency to control the motor's RPM.
For industrial use on grid power the controller converts the 60 Hz
input to whatever frequency it needs.
Bruce
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| User: "" |
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| Title: Re: efficiency of regenerative braking? |
21 Dec 2006 03:48:44 AM |
|
|
wrote:
zzbunker@netscape.net wrote:
wrote:
Bret Cahill wrote:
| What is the efficiency of regenerative braking in electric
| vehicles?
High.
Isn't regenerative braking just the DC traction motors running
backwards?
An alternator that worked over a broad rpm range touted 70% efficiency
in a recent patent.
It would be interesting if they could beat that.
Bret Cahill
As others here have pointed out, the motors don't run backwards, the
electrical current does. When DC electric motors run they also act as
generators. The voltage produced by the generator, sometimes called
the "back EMF" is proportional to the rpm. As the rpm goes up this
back EMF goes up and limits how high the rpm will go with no load on
the motor.
One way to make the motor charge the battery is to use a motor with
field windings and control the back EMF by controling the field
current. This same idea is used for the "voltage regulator" in many
automotive alternators.
Actually I think the most efficient systems in use today are varialbe
frequency AC systems. Many of the same ideas work and some are easier
to impliment with AC rather than DC.
No they don't. Varible Frequency networks
are usually called servo motors, Which
are as often as not these days, being
replaced the computers, rather than electrical systems.
Wide area power distriubtion genarators
don't even work unless you have them synchronised
to about 60Hz +/- 0.1 Hz,
We weren't talking about networks, we were talking about motors and
controllers.
Just by saying "motors and controllers" means you're
tallking about a network, It's just a local separable network.
There are controllers that can convert the DC from
batteries info AC and vary the frequency to control the motor's RPM.
That's only because DC is not a voltage, it's a capacitance.
For industrial use on grid power the controller converts the 60 Hz
input to whatever frequency it needs.
It's unlikely it can it convert to 100 GHz, since
that's the frequency band weather balloons use,
Bruce
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| User: "Eeyore" |
|
| Title: Re: efficiency of regenerative braking? |
21 Dec 2006 04:43:22 AM |
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"zzbunker@netscape.net" wrote:
bsr3997@my-deja.com wrote:
There are controllers that can convert the DC from
batteries info AC and vary the frequency to control the motor's RPM.
That's only because DC is not a voltage, it's a capacitance.
Do you always talk ***** ?
Graham
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| User: "" |
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| Title: Re: efficiency of regenerative braking? |
21 Dec 2006 08:36:16 AM |
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Eeyore wrote:
"zzbunker@netscape.net" wrote:
bsr3997@my-deja.com wrote:
There are controllers that can convert the DC from
batteries info AC and vary the frequency to control the motor's RPM.
That's only because DC is not a voltage, it's a capacitance.
Do you always talk ***** ?
Well it's invariant in sci.energy.
Since Bill Clinton moderates the norron group,
and sci.chem funds it with kickbacks to
the Neo Commie coommittee for the
promotion of reverse osmosis and sychronicity..
Graham
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| User: "Eeyore" |
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| Title: Re: efficiency of regenerative braking? |
21 Dec 2006 07:54:01 PM |
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"zzbunker@netscape.net" wrote:
Eeyore wrote:
"zzbunker@netscape.net" wrote:
bsr3997@my-deja.com wrote:
There are controllers that can convert the DC from
batteries info AC and vary the frequency to control the motor's RPM.
That's only because DC is not a voltage, it's a capacitance.
Do you always talk ***** ?
Well it's invariant in sci.energy.
Since Bill Clinton moderates the norron group,
and sci.chem funds it with kickbacks to
the Neo Commie coommittee for the
promotion of reverse osmosis and sychronicity..
Fine. You're an insane k00k.
No problem.
Graham
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| User: "" |
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| Title: Re: efficiency of regenerative braking? |
21 Dec 2006 08:26:49 PM |
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Eeyore wrote:
"zzbunker@netscape.net" wrote:
Eeyore wrote:
"zzbunker@netscape.net" wrote:
bsr3997@my-deja.com wrote:
There are controllers that can convert the DC from
batteries info AC and vary the frequency to control the motor's RPM.
That's only because DC is not a voltage, it's a capacitance.
Do you always talk ***** ?
Well it's invariant in sci.energy.
Since Bill Clinton moderates the norron group,
and sci.chem funds it with kickbacks to
the Neo Commie coommittee for the
promotion of reverse osmosis and sychronicity..
Fine. You're an insane k00k.
And you're a Buckeyball wannabee moron who should really
post to alt,sci.clinton rather than a newsgroup.
No problem.
Graham
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| User: "Eeyore" |
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| Title: Re: efficiency of regenerative braking? |
21 Dec 2006 09:01:43 PM |
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"zzbunker@netscape.net" wrote:
Eeyore wrote:
"zzbunker@netscape.net" wrote:
Eeyore wrote:
"zzbunker@netscape.net" wrote:
bsr3997@my-deja.com wrote:
There are controllers that can convert the DC from
batteries info AC and vary the frequency to control the motor's RPM.
That's only because DC is not a voltage, it's a capacitance.
Do you always talk ***** ?
Well it's invariant in sci.energy.
Since Bill Clinton moderates the norron group,
and sci.chem funds it with kickbacks to
the Neo Commie coommittee for the
promotion of reverse osmosis and sychronicity..
Fine. You're an insane k00k.
And you're a Buckeyball wannabee moron who should really
post to alt,sci.clinton rather than a newsgroup.
You're a clueless insane k00k.
Graham
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| User: "" |
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| Title: Re: efficiency of regenerative braking? |
22 Dec 2006 01:04:43 AM |
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Eeyore wrote:
"zzbunker@netscape.net" wrote:
Eeyore wrote:
"zzbunker@netscape.net" wrote:
Eeyore wrote:
"zzbunker@netscape.net" wrote:
bsr3997@my-deja.com wrote:
There are controllers that can convert the DC from
batteries info AC and vary the frequency to control the motor's RPM.
That's only because DC is not a voltage, it's a capacitance.
Do you always talk ***** ?
Well it's invariant in sci.energy.
Since Bill Clinton moderates the norron group,
and sci.chem funds it with kickbacks to
the Neo Commie coommittee for the
promotion of reverse osmosis and sychronicity..
Fine. You're an insane k00k.
And you're a Buckeyball wannabee moron who should really
post to alt,sci.clinton rather than a newsgroup.
You're a clueless insane k00k.
You're a fucking ozone-depleted retard
who should practice ***** surfing with Mao's Tomb.
Since Clinton only hires Massad morons.
and Bush is too coked-up to find his way to
the Humvee Shop.
Graham
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| User: "Eeyore" |
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| Title: Re: efficiency of regenerative braking? |
17 Dec 2006 08:15:12 AM |
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|
Bret Cahill wrote:
| What is the efficiency of regenerative braking in electric
| vehicles?
High.
Isn't regenerative braking just the DC traction motors running
backwards?
No.
Graham
.
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| User: "Bret Cahill" |
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| Title: Re: efficiency of regenerative braking? |
17 Dec 2006 09:13:43 AM |
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Eeyore wrote:
Bret Cahill wrote:
| What is the efficiency of regenerative braking in electric
| vehicles?
High.
Isn't regenerative braking just the DC traction motors running
backwards?
No.
How is the electricity being regenerated? By another component, say,
an alternator or DC generator mounted on the same shaft as the traction
motor?
Alternators generally aren't all that efficient off the design point
rpm.
Bret Cahill
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| User: "Eeyore" |
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| Title: Re: efficiency of regenerative braking? |
17 Dec 2006 01:48:09 PM |
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Bret Cahill wrote:
Eeyore wrote:
Bret Cahill wrote:
| What is the efficiency of regenerative braking in electric
| vehicles?
High.
Isn't regenerative braking just the DC traction motors running
backwards?
No.
How is the electricity being regenerated? By another component, say,
an alternator or DC generator mounted on the same shaft as the traction
motor?
It's called motor-generator action.
Alternators generally aren't all that efficient off the design point rpm.
Traction motors aren't alternators. What gave you that idea about the rpm anyway
?
Graham
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| User: "Bret Cahill" |
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| Title: Re: efficiency of regenerative braking? |
17 Dec 2006 03:32:35 PM |
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What gave you that idea about the rpm anyway?
You know how to brake at just one rpm?
Bret Cahill
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| User: "Sorcerer" |
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| Title: Re: efficiency of regenerative braking? |
17 Dec 2006 05:01:11 PM |
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"Bret Cahill" <BretCahill@aol.com> wrote in message =
news:1166391155.578018.201380@n67g2000cwd.googlegroups.com...
|> What gave you that idea about the rpm anyway?
|=20
| You know how to brake at just one rpm?
You know how much current it takes to accelerate a train to just=20
one rpm, clueless fuckhead?
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| User: "Bill Snyder" |
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| Title: Re: efficiency of regenerative braking? |
17 Dec 2006 05:09:15 PM |
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On Sun, 17 Dec 2006 23:01:11 GMT, "Sorcerer"
<Headmaster@hogwarts.physics_e> wrote:
"Bret Cahill" <BretCahill@aol.com> wrote in message news:1166391155.578018.201380@n67g2000cwd.googlegroups.com...
|> What gave you that idea about the rpm anyway?
|
| You know how to brake at just one rpm?
You know how much current it takes to accelerate a train to just
one rpm, clueless fuckhead?
It would depend. Do Brit trains spin on their long axis, or
end-over-end?
--
Bill Snyder [This space unintentionally left blank.]
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| User: "Y.Porat" |
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| Title: Re: efficiency of regenerative braking? |
21 Dec 2006 03:39:31 AM |
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Sorcerer wrote:
"Bret Cahill" <BretCahill@aol.com> wrote in message news:1166391155.578018.201380@n67g2000cwd.googlegroups.com...
|> What gave you that idea about the rpm anyway?
|
| You know how to brake at just one rpm?
You know how much current it takes to accelerate a train to just
one rpm, clueless fuckhead?
------------------
it i s not only for trains
it is as well or mostly for cars !!
(they are the great energy wasters and poluters !!
Y.P
-----------------------------------------
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| User: "Eeyore" |
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| Title: Re: efficiency of regenerative braking? |
17 Dec 2006 04:13:48 PM |
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Bret Cahill wrote:
What gave you that idea about the rpm anyway?
You know how to brake at just one rpm?
What *are* you talking about ?
Have you gone mad ?
Graham
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| User: "Bret Cahill" |
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| Title: Re: efficiency of regenerative braking? |
17 Dec 2006 10:12:08 PM |
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What gave you that idea about the rpm anyway?
You know how to brake at just one rpm?
What *are* you talking about ?
By definition, braking takes places over a wide range of rpms.
But generators and alternators ain't so efficient over a wide range of
rpms.
What's the solution?
Bret Cahill
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| User: "Sorcerer" |
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| Title: Re: efficiency of regenerative braking? |
17 Dec 2006 10:23:17 PM |
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"Bret Cahill" <BretCahill@aol.com> wrote in message =
news:1166415128.370364.236970@16g2000cwy.googlegroups.com...
|> > > What gave you that idea about the rpm anyway?
|=20
| > > You know how to brake at just one rpm?
|=20
| > What *are* you talking about ?
|=20
| By definition, braking takes places over a wide range of rpms.
|=20
| But generators and alternators ain't so efficient over a wide range of
| rpms.
|=20
| What's the solution?
Same as your car. Use the handbrake, idiot.
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| User: "Eeyore" |
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| Title: Re: efficiency of regenerative braking? |
17 Dec 2006 11:43:00 PM |
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Sorcerer wrote:
"Bret Cahill" <BretCahill@aol.com> wrote
|> > > What gave you that idea about the rpm anyway?
|
| > > You know how to brake at just one rpm?
|
| > What *are* you talking about ?
|
| By definition, braking takes places over a wide range of rpms.
|
| But generators and alternators ain't so efficient over a wide range of
| rpms.
|
| What's the solution?
Same as your car. Use the handbrake, idiot.
You'll need friction braking in addition to dynamic braking for rapid braking anyway.
Hence it can also be used to bring a vehicle to a stop.
Graham
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| User: "" |
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| Title: Re: efficiency of regenerative braking? |
19 Dec 2006 01:37:04 AM |
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Bret Cahill wrote:
What gave you that idea about the rpm anyway?
You know how to brake at just one rpm?
What *are* you talking about ?
By definition, braking takes places over a wide range of rpms.
But generators and alternators ain't so efficient over a wide range of
rpms.
What's the solution?
Replace the RPM's with RPS's.
Since the only cranks who even use RPMs
is GM & Asswipes Inc,
Bret Cahill
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