[Solved] Excitation of a car alternator

Renewable energies except solar electric or thermal (seeforums dedicated below): wind turbines, energy from the sea, hydraulic and hydroelectricity, biomass, biogas, deep geothermal energy ...
abaddon
I learn econologic
I learn econologic
posts: 15
Registration: 09/05/10, 23:02

[Solved] Excitation of a car alternator




by abaddon » 11/05/10, 19:45

Hello everybody,

well I must surely ask a question that you have seen pass thousands of times, but I do not really find a satisfactory answer to my question.

Here, I have a car alternator which has 3 terminals. 2 for the battery and one for the excitation. It is this terminal that poses my problem. I would like to know what signal should I provide to the voltage regulator that takes care of the excitation? I applied several DC voltages of different values ​​and observed that the regulator behaves a bit like a 4 Ohm resistor. I did not go beyond 12 V: 3A.

In fact, the greater the excitation current, the greater my stator voltage, but I don't really know what the regulator does and it bothers me to have a black box in the middle of my assembly ...

In fact, I thought that it was necessary to apply 12V (typically from the battery), but that means that it will permanently require 12 · 3 = 36W for excitation. On a 720W alternator it's still 5% lost just for the excitement ... it seems unacceptable.

In fact, my alternator will be used on a wind turbine assembly, but I will not modify it, because I have to carry out an assembly which can be reproduced most simply and which does not require any particular skill. I would have a transmission system that I have already pre-sized.

So .. So basically my biggest misunderstanding is: how is the voltage regulator that takes care of the excitation and what should I provide as an input signal?

Thanks a lot for your help.
Last edited by abaddon the 31 / 05 / 10, 14: 46, 1 edited once.
0 x
User avatar
zorglub
I posted 500 messages!
I posted 500 messages!
posts: 501
Registration: 24/11/09, 10:12




by zorglub » 11/05/10, 21:05

the regulator is used to regulate ...
in fact when your voltage will exceed 12 V and a few extra volts; it will de-energize the alternator which will avoid overcharging your battery
if at this time you charge the battery (eg by putting the headlights on) you will have a voltage drop which will cause your regulator to activate your alternator
this is the principle of the regulator, although some are more complicated

if you want to do without a regulator you "shunt" the positive terminal of the alternator and this 3rd terminal and you will have voltage on the alt.
in this case, a permanent charge is required for the alternator to be charged

when the watts spent unnecessarily, they correspond to the value of the impedance of the excitation winding in the alternator (R + L + C) which is normal
0 x
every morning you look naked in a large ice after 3 minutes you will see that your home and your worst picture ......
abaddon
I learn econologic
I learn econologic
posts: 15
Registration: 09/05/10, 23:02




by abaddon » 11/05/10, 21:21

Hello, thanks for the reply.
zorglub wrote:the regulator is used to regulate ...
that I thought well :-) In fact my question is: how? a bipolar mounting beast, like degenerate common transmitter followed by a common collector?

Otherwise, that did not answer my question. What voltage should be applied to the regulator?
0 x
User avatar
zorglub
I posted 500 messages!
I posted 500 messages!
posts: 501
Registration: 24/11/09, 10:12




by zorglub » 11/05/10, 21:30

well if you connect the most to your 3rd terminal you will necessarily have 12 volts
0 x
every morning you look naked in a large ice after 3 minutes you will see that your home and your worst picture ......
User avatar
zorglub
I posted 500 messages!
I posted 500 messages!
posts: 501
Registration: 24/11/09, 10:12




by zorglub » 11/05/10, 21:33

this is why permanent magnets are mounted on this kind of device ': saving lost power
0 x
every morning you look naked in a large ice after 3 minutes you will see that your home and your worst picture ......
abaddon
I learn econologic
I learn econologic
posts: 15
Registration: 09/05/10, 23:02




by abaddon » 11/05/10, 21:39

yes, totally agree with permanent magnets. But there I can not mount a permanent magnet because my wind turbine will be in operation in the bush in Africa, and if the alternator breaks, it is easier to replace it with another than to have to redo all the modification, especially since neodymium magnets do not run the bush, if I can use the expression : Cheesy:

So answer to my question, we simply connect the regulator input to + 12V. It is therefore a voltage supply and not current.

sure of that?

thank you for the answer :-)
0 x
Alain G
Econologue expert
Econologue expert
posts: 3044
Registration: 03/10/08, 04:24
x 3




by Alain G » 12/05/10, 03:01

Hi Abaddon!


Usually the case is the ground, a threaded rod to receive a large terminal is the positive and the other 2 are the excitation and the power of the dashboard voltmeter!
:D
0 x
Stepping behind sometimes can strengthen friendship.
Criticism is good if added to some compliments.
Alain
Other
Pantone engine Researcher
Pantone engine Researcher
posts: 3787
Registration: 17/03/05, 02:35
x 12




by Other » 12/05/10, 04:13

Hello

Most of the current alternators are autofeild they provide their excitation at a certain speed, there is a file + which will follow the regulator which provides before the autofield diodes, this helps starting for excitation, but without plugging it works also it does not charge at slowdown, but once initiated it charges.

There are different models, Bosh, Prestolye, the most widespread and more economical to buy is more robust it is the Delco Remy
I put them in all Gulf, Jetta, Mercedes vehicles, agricultural tractors the parts are abundant, available, inexpensive, and their power varies from 60 amperes, 80, 100 amps almost in the same mounting format.

Image
0 x
Alain G
Econologue expert
Econologue expert
posts: 3044
Registration: 03/10/08, 04:24
x 3




by Alain G » 12/05/10, 04:26

Hi André!

The diagram you have posted is for the positive mass!

On which vehicle is mass used in positive?
:?:
0 x
Stepping behind sometimes can strengthen friendship.

Criticism is good if added to some compliments.

Alain
User avatar
zorglub
I posted 500 messages!
I posted 500 messages!
posts: 501
Registration: 24/11/09, 10:12




by zorglub » 12/05/10, 07:54

sure of that?

look at the section of the wire which is used for the excitation
the intensity will be that corresponding to the section if you calculate: 5 A / mm2 approximately you will see the maximum absorbed by the excitation - anyway you can make measurements as you already made by loading the alternator and you will see that the excitation is (f) of the load with a maximum which is limited by the impedance of the winding
you may go up to 10 A. which depends on the characteristics of the alternator (see if you have information on the technical plate or on the regulator)
but the excitation varies with the charge automatically
0 x
every morning you look naked in a large ice after 3 minutes you will see that your home and your worst picture ......

Back to "hydraulic, wind, geothermal, marine energy, biogas ..."

Who is online ?

Users browsing this forum : No registered users and 169 guests