Christophe
I just tested another universal motor which does not produce current if I do not provide a voltage on the brushes.
There are two kinds of universal motor, so you were right.
Universal motor alternator or current generator
- chatelot16
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a universal motor without any connection modification makes a dynamo with serial excitation: therefore which only makes tension if there is current: therefore which can only work under load, never empty ...
in addition so that it makes dynamo it is necessary to turn the reverse of the direction of rotation in motor
only application: fren of certain electric machine: hedge trimmer or chainsaw: in the trigger there is an inverter which crosses the connection as if to turn inside out and which short circuits everything: conclusion it brakes abruptly as soon as you let go trigger
to make a real dynamo with a universal one needs in the excitation as much current as it produces, but at lower voltage: a real dynamo has a greater number of turns in fine wire at the excitation for have a lower excitation current and a voltage closer to the nominal voltage
in addition so that it makes dynamo it is necessary to turn the reverse of the direction of rotation in motor
only application: fren of certain electric machine: hedge trimmer or chainsaw: in the trigger there is an inverter which crosses the connection as if to turn inside out and which short circuits everything: conclusion it brakes abruptly as soon as you let go trigger
to make a real dynamo with a universal one needs in the excitation as much current as it produces, but at lower voltage: a real dynamo has a greater number of turns in fine wire at the excitation for have a lower excitation current and a voltage closer to the nominal voltage
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- chatelot16
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to excite in alternative, I forgot one thing: the excitation winding is inductive: to pass the right current there needs more voltage than continuous: if the excitation generator is a transistor amp it will a disaster: so that the inductive voltage is not a loss of energy you need a resonant capacitor at 50hz with the inductance of the excitation
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Re: Universal motor in generator
bobono wrote:I just tested another universal motor which does not produce current if I do not provide a voltage on the brushes.
Well I have never tested in this "sense": I have always excited the stator and measured the voltage produced on the 2 brushes ... as recommended by Chatelot ...
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Universal motor in generator
I have just found a motor with 6 permanent magnets widely diffused which one can find for not very expensive.
Voir les photos
I have not yet tested the generator
Voir les photos
I have not yet tested the generator
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I just made measurements in TRUE RMS calculation with this velleman pps10 portable oscilloscope : https://www.econologie.com/shop/oscillos ... p-232.html
It is therefore much more significant than the previous measurements, in fact, it has nothing to do: there is almost no AC component at all! Measurement with "full" screwdriver given for 700 rpm max. I suppose we are therefore not far from 700 rpm but no more.
The component is essentially continuous, here is a screenshot of the oscilloscope for the strongest excitement (see 2nd photo):
Legend from top to bottom:
- time base
- voltage peak on the screen
- DC voltage
- AC voltage
- RMS voltage
- Hold = data Hold = screenshot
- volt by division
- Type of operation
The curves are coming!
It is therefore much more significant than the previous measurements, in fact, it has nothing to do: there is almost no AC component at all! Measurement with "full" screwdriver given for 700 rpm max. I suppose we are therefore not far from 700 rpm but no more.
The component is essentially continuous, here is a screenshot of the oscilloscope for the strongest excitement (see 2nd photo):
Legend from top to bottom:
- time base
- voltage peak on the screen
- DC voltage
- AC voltage
- RMS voltage
- Hold = data Hold = screenshot
- volt by division
- Type of operation
The curves are coming!
Last edited by Christophe the 12 / 01 / 09, 13: 28, 2 edited once.
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a) RMS output voltage / Excitation voltage at 700 rpm:
b) RMS output power assuming that the output intensity = excitation intensity (as Chatelot predicted above):
It would therefore appear that the point of best excitation for this engine and at 700 rpm is around 2 Volts? Yes No? Opinions?
b) RMS output power assuming that the output intensity = excitation intensity (as Chatelot predicted above):
It would therefore appear that the point of best excitation for this engine and at 700 rpm is around 2 Volts? Yes No? Opinions?
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From my little and miserable year of automotive electronics, I learned that it was necessary to "start" the alternator with current coming from the battery and then afterwards, when it is well started, a relay device comes to change the connection. .
Clear:
it is first necessary to seriously excite the rotor with continuous to start the alternator. And then when it is gone a relay can put it in series in the main circuit
Clear:
it is first necessary to seriously excite the rotor with continuous to start the alternator. And then when it is gone a relay can put it in series in the main circuit
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elephant Supreme Honorary éconologue PCQ ..... I'm too cautious, not rich enough and too lazy to really save the CO2! http://www.caroloo.be
Hello
If you want to get the most out of your generator it is the maximum excitation, the limit is when you reach the magnetic saturation of the poles and when you reach the maximum allowed to the rotor, which is limited to a linear speed of the collector and above all the resistance of the winding to centrifugal force (the lines seek to tear between the collector and their passage in the notches certain rotor has a hoop, others are poured into epoxy
Normally we do not use the excitation to its maximum, we modulate it to control the voltage depending on the flow and RPM
I don't know which alternator model you tried? But with a Delco Remy autofeil no need for excitement the remanent of the rotor is enough to start it.
Coin it in a vice with a piece of allen key planted in the pulley axis connect the output wire + on the field (S) and on the (F) and with a drill drives the alternator while it turns branch a light 12 volts 40watts and crampone you after the drill ..
Andre
It would therefore appear that the point of best excitation for this engine and at 700 rpm is around 2 Volts? Yes No? Opinions?
If you want to get the most out of your generator it is the maximum excitation, the limit is when you reach the magnetic saturation of the poles and when you reach the maximum allowed to the rotor, which is limited to a linear speed of the collector and above all the resistance of the winding to centrifugal force (the lines seek to tear between the collector and their passage in the notches certain rotor has a hoop, others are poured into epoxy
Normally we do not use the excitation to its maximum, we modulate it to control the voltage depending on the flow and RPM
it is first necessary to seriously excite the rotor with continuous to start the alternator. And then when it is gone a relay can put it in series in the main circuit
I don't know which alternator model you tried? But with a Delco Remy autofeil no need for excitement the remanent of the rotor is enough to start it.
Coin it in a vice with a piece of allen key planted in the pulley axis connect the output wire + on the field (S) and on the (F) and with a drill drives the alternator while it turns branch a light 12 volts 40watts and crampone you after the drill ..
Andre
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André I try a universal engine in alternator mode, you have a photo here: https://www.econologie.com/forums/moteur-uni ... t6819.html
Yes André, only on this motor, the excitation power goes up very quickly (I exceeded 30W / 3A on the excitation while the motor is given, in motor mode, at 225W) and I therefore think that it There is an optimum at the excitation voltage in order to have the best efficiency of the motor!
Otherwise I started (finally found the time !!) some load tests (20W 12V AC / DC halogen bulb) with my 2nd screwdriver which turns at 1200 rpm (I stopped at 5V of excitation to not not slam the 12V bulb which was already at 14V):
No load and load voltage at 1200 RPM:
Output power / Excitation power
Output power / excitation power ratio:
You see André, this report, on this engine, only decreases: the engine would therefore be more efficient with a weak excitation!
Anyway, I'm starting to get the impression that the power of this universal motor in generator mode will remain very low: the no-load voltage difference between 700 RPM and 1200 RPM is still significant, which gives me good hope if I raise the RPMs ... but the voltage drop at no load / load of the 1st graph is worrying. I specify
So by mounting the RPM we can therefore hope to have an interesting power? Below 100W, I start by mounting this motor as a generator on the paddle wheel. We are far from it!
So mount the RPM yes but at what technological and reliability cost? If it is to run at 3000 or 4000 rpm with poor efficiency and excitement to manage, you might as well take a car alternator (I have one waiting for a 50A test).
Output voltages between 700 and 1200 RPM depending on the excitation voltage:
Otherwise I confirm what Chatelot said above: the excitation current is very close to the output current!
Question: for an asynchronous generator what is generally the ratio: excitation power / optimum output power? What order of magnitude?
Yes André, only on this motor, the excitation power goes up very quickly (I exceeded 30W / 3A on the excitation while the motor is given, in motor mode, at 225W) and I therefore think that it There is an optimum at the excitation voltage in order to have the best efficiency of the motor!
Otherwise I started (finally found the time !!) some load tests (20W 12V AC / DC halogen bulb) with my 2nd screwdriver which turns at 1200 rpm (I stopped at 5V of excitation to not not slam the 12V bulb which was already at 14V):
No load and load voltage at 1200 RPM:
Output power / Excitation power
Output power / excitation power ratio:
You see André, this report, on this engine, only decreases: the engine would therefore be more efficient with a weak excitation!
Anyway, I'm starting to get the impression that the power of this universal motor in generator mode will remain very low: the no-load voltage difference between 700 RPM and 1200 RPM is still significant, which gives me good hope if I raise the RPMs ... but the voltage drop at no load / load of the 1st graph is worrying. I specify
So by mounting the RPM we can therefore hope to have an interesting power? Below 100W, I start by mounting this motor as a generator on the paddle wheel. We are far from it!
So mount the RPM yes but at what technological and reliability cost? If it is to run at 3000 or 4000 rpm with poor efficiency and excitement to manage, you might as well take a car alternator (I have one waiting for a 50A test).
Output voltages between 700 and 1200 RPM depending on the excitation voltage:
Otherwise I confirm what Chatelot said above: the excitation current is very close to the output current!
Question: for an asynchronous generator what is generally the ratio: excitation power / optimum output power? What order of magnitude?
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