Universal motor alternator or current generator

[Christophe]

How to make a generator or alternator with recovery engines in the most optimum and reliable way possible?

As part of my paddlewheel "project": https://www.econologie.com/forums/tambour-de ... t6303.html i need to find a generator. I think this is the case for a lot of people with a renewable energy project and I didn't want to go into the "commercial" logic of big investments.

Apparently luck smiles for me because I have recovered (with the 2 recovery drums) 2 washing machine motors, here is one of the 2:



These 2 motors are called "universal motor" with carbon (being able to work in CC and AC) which are (thank you chatelot) reversible without any modification. The purpose of the subject is to find the limits and optimum operating point in generator mode.

So I asked a few questions and had very interesting answers on this subject: https://www.econologie.com/forums/cablage-mo ... t6816.html which quickly became out of topic from which the creation of this new subject.

Here is a small summary of what has already been done or said.

The basics you need to know about universal engines in generator mode

there is not a universal transform engine is also a dynamo

the stator winding is excitation, DC comes from coal

but watch the current of excitation is roughly the same as the current product: it is not a disaster because the excitation voltage is much lower than the output voltage: a converter decoupage is essential to the excitation without loss

pifometrique example (it will make a precise measurement)
current product 200V 2A
excitation 5V 2A
but it is driving the motor rated speed: when the speed decreases the power output and lower power excitation remains constant

original method: make a generator of sinusoidal excitation electronics 50 Hz and recovered by coal power 50 Hz although the speed is variable

I've never seen use this principle but it has to serve pourais 50Hz an alternator with a turbine that spins very quickly

And here are the curves 2, how did I do it?

a) Adjustable DC excitation (9 measurement points from 0.48V to 10.30 V). Made by a laboratory 12V 3A stabilized power supply ... I do not exceed the 10.30 because the amperage reaches its maximum for the power supply!

b) Excitation on the stator, output on the rotor as indicated by Chatelot (the reverse can not be too?)

c) I activate the rotor with a small screwdriver (fully). Hoping that the speed of rotation is constant ...

d) I made a DC and AC measurement with an ultrabasic voltmeter. How much difference do you think? We must be far from the sine of 50Hz AC side ... surely for that ... Tomorrow I put the oscillo on it that I received for Christmas !!

Results:

a) Output voltage / excitation voltage


b) Output voltage / excitation power


Is there a "shady" point at 9.02 Volts in DC? I have trouble reading?

What do the experts think about electric motors / generators? In any case, a big thank you lv13r and Chatelot in absentia (if it says in this context)

Well we're off topic finally ... Here I am excited!

And chatelot (always and again) that confirms my doubt about AC measurements:

I just read a little better: you still exite in cc: the output is always in cc

and you have fallen into the trap of the little multimeter who only measures an alternace on 2 by multiplying by 2 to make good average with the other alternation which is not measured: if you put your voltmetre AC in the other meaning you will always have 0

to have the alternative it is really necessary to exite in alternative, for example with a transformer 220v has secondary 5v or 12v ...

And here are the last exchanges https://www.econologie.com/forums/post110631.html#110631

to read your curves well it would be necessary to put the tension of exitation on a linear scale: you will see that beyond a certain exitation the tension of exit does not increase in proportion: it is sign that the magnetic circuit saturates , so that the yield becomes bad

Good point is what it seemed to me (there was a maximum / optimum) because 30W excitation (for a given engine for 225W) seems really huge!

at random without tracing the curve I would say not to exceed 5v

Ok I guess there is an optimum to be determined case by case (depending on the RPM and type of windings)

Question: Does the load count? That is to say ideally should a variable excitation depending on the load?

to increase the tension it is necessary to increase the speed

it is not a type of engine adapted to low speed

Ben I'm still surprised by the results because a screwdriver turns quite weakly (I have more doc but I do not think it exceeds the 400-500 rpm) it is not a drill!

Ah my humble opinion it will suffice for what I want to do.

Today I will try to excite with 12V AC to see if it's better? And I will connect the oscilloscope!

ps: for those who want to change a generator asynchronous motor go on this topic: https://www.econologie.com/forums/moteur-asy ... t6820.html

Apparently it is enough to add a capacitor in // of the power supply (in single-phase, in three-phase it is necessary to pass in star if possible and to add 3 capacitors).

[chatelot16]

Exit in 50hz will not be better

the performance of a universal motor is better continuously than in alternative, but its behavior is different: continuously it is too good and embaled empty

in generator I think that in alternative there will be more voltage drop with the load than continuous

the only interest of making the alternative is to 220v well regulated: it is necessary to run the engine at high speed, and be content with a poor performance: the universal are especially made to be light

to make a low power it is obviously necessary to stay in direct current

[Christophe]

The fact is that I do not know yet if I will generate in 12V CC or AC ...

The choice will be imposed by itself according to the quality of the current that can be obtained with these 2 motors and the possible "treatments" of the current to make it a usable current (my "final" goal would be to supply an office of complete work (pc + printer) and for this a DC buffer battery might be essential (power peaks)).

In any case there would be an inverter on the PC.

[boubka]

I see that you talk a lot about making the alternative with a universal motor, for me it is not possible ...
have you tried?
can you confirm me your tests?

[quartz]

Good evening everyone,

I read the topic diagonally, a universal engine can produce the alternative, but you have to tinker a little.

By definition a universal motor is a motor that can be powered continuously or alternatively.

The field inductor (stator) is often in series with the rotor,
so if the current reverses periodically,
the inductive field varies at the same rate as the torque current.
So vectorially the resulting sign remains identical.

To transform a universal motor into a generator, it is necessary firstly to supply the inductors (stator) with current.
This requires changing the type of wiring, (series) between the rotor and the stator, to make them independent.
Thus we can feed the stator only,
and recover the current produced on the motor manifold.
if the inductive current is alternative, we will recover AC current on the collector is a fact.
this would be impossible with a DC motor that often has permanent magnets.

On the other hand, some industrial motors wound wound are called DC motors, because the stator pole pieces (inductor) are non-laminated steel therefore subject to eddy currents.

I have made short, that the purists do not hold me rigor.

A + + +

[boubka]

ok, but it owes a really rotted yield.
for the frequency I am dubious.
to make the alternative nothing is worth a rotor wound rings or synchronous motor in a word an alternator
we learn more about this forum that school

[chatelot16]

On the other hand, some industrial motors wound wound are called DC motors, because the stator pole pieces (inductor) are non-laminated steel therefore subject to eddy currents.

this is the main difference between a DC motor and a universal motor

the universal motor has the stator in sheet stacked like a transformer to support the alternative without too much loss

the DC motor has a solid iron stator: put it in alternating heat like an induction furnace

anyway it is impossible to make a big universal engine: in 50hz 2000w is the maximum practical

there was a network at 16hz1 / 3 to make bigger universal motor ...

[chatelot16]

other note: the internal voltage of a motor is the power supply voltage minus the resistive and inductive voltage drop

in generator the maximum internal voltage is the same: the output voltage is the internal voltage minus the voltage drops: therefore much lower than the nominal voltage in motor

it will be considered lucky if a universal motor 220v makes a generator 110v

for the asynchronous motor it is the mechanical power which is given as the nominal power: alas for the universal motor it is always the electric consumed power which is given: alas there are drills 700w which have less mechanical power than 500w

So anyway with these motor that are heavily overloaded at their rated voltage, we have to look for lower voltage operating conditions less worst, and be content with lower power

[quartz]

Yes for the performance of a universal engine generator do not expect one of the miracles,
clearly it's not done for that, they are explanations for fun !!
The coal collector itself is already a brake, so that's it.

If no it is more clever is to recycle a big stepper motor, it comes out sinus not ugly at all.
The higher the number of steps per revolution, the higher the output frequency.

But this is another story.

A + + +

[Christophe]

Ben no it's not for fun it's for that: https://www.econologie.com/forums/tambour-de ... t6303.html and I intend to go all the way ... at least try!

And if ever it works "well" with a "tinkered" alternator with a universal motor, then it may be possible to buy a real alternator of a small wind turbine for example.

Well, I'm coming back from the lab:

a) I tried an excitement 12 V AC 50Hz (same connection as yesterday): it gives nothing at all? Chatelot, what do you think?

b) I tested the 2ieme engine according to the same test as the 1er (without making a survey for the moment because there is nothing easily accessible to couple to the tree). He behaves in the same way as the other on the principle. I have the impression that it delivers at lower excitation voltage. We'll see when I find a mating room.

c) I connected a stabilized power supply on the 1er motor (that of the curves of yesterday) and 4.90V food excitement under 12.1V at max!

d) I plugged the pocket oscilloscope into it: it is rather cacaphonic voltage coming out ... Tomorrow I will make screens and find some "interesting" stuff.

There you are!