Stop an universal motor electronically

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  #1  
Old 04-13-11, 04:38 PM
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Stop an universal motor electronically

Hello everybody!

I have a question which could seems easy for some but which gives me hard times.I want to know how to slow down then cut the supply of an universal motor (230VAC, 16A) and all of that electronically because this system will be in a tool and will be activated by an hypothetical sensor(then driven by tension or intensity).

If it's not clear please ask me.
 
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  #2  
Old 04-13-11, 05:00 PM
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Welcome to the forums! It isn't clear what you are doing, so we'll go ahead and ask...what are you doing? To stop a motor, the use of a half wave rectifier in the cover turns the motor into a generator with an opposite field until it reaches almost zero rpm. BUT, you are in France, voltages are different. Maybe our local/French electrician can fill you in better. Marc will be along shortly, so hang in there.
 
  #3  
Old 04-14-11, 03:35 AM
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@Chandler
In France the voltage is about 230VAC and 50 to 60 hz.
For the rectifier, I don't know how it could brake the motor and then stop it electronically in case of misuse or exceeded a certain imposed limit of intensity.
That's what I have to do and it's like a chinese puzzle...
Can you tell me how I can reach Mark or somebody who could help me?

PS: thank you for your answer
 
  #4  
Old 04-14-11, 07:16 AM
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I"m not clear on your question. It is possible to drive a "universal" motor with most lamp dimmers, (triac based semiconductor). Since universal motors can drive from either DC or AC, an electronic brake (active braking) might be more difficult than on an induction motor. Do you need to brake the motor? or just on/off/speed control?

Also, very the size of this motor. 230v @ 16 amp is a large motor. I've never seen a universal motor that large, since speed regulation is poor on universal motors and brush life would be a concern.
 
  #5  
Old 04-14-11, 11:57 AM
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oh sorry telecom I have to rectify the intensity is 8.5 Amps and not 16!
I have seen it today and it reaches 16 amps sometimes when it 's in action.
For the brake of the motor, cut the rotation of the broach of the drill electronically is my goal.
 
  #6  
Old 04-14-11, 12:38 PM
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I need to ask you why you think this is a "universal" motor? Is it brushed? Is it speced for AC or DC? Do you know what an "induction" motor is?
 
  #7  
Old 04-14-11, 02:52 PM
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I know what's is in theory an induction motor . But mine has brushes and it's a drill. It's an universal motor for sure which is working just in Vac because there are no rectifier.
I just have seen that there are two questions ,how to slow down (maybe put a resistance at the right place) and how to stop the supply (perhaps by some commutation componants...) electronically.
 
  #8  
Old 04-14-11, 06:46 PM
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I've done some dynamic braking designs, but never for a universal motor. I'm not sure there is a commonly used electronic type for braking, other than simple removal of power. Of course, a mechanical brake will work. You could use a solid state relay for power control. To slow the speed, like I said, a simple, lamp dimmer will work, if rated for the load. Alternately, a fixed power resistor will work, using various numbers and values for the desired speed. One of the characteristics with universal, series wound motors is the general lack of speed stability with load and input voltage, usually seen as a disadvantage.
 
  #9  
Old 04-14-11, 08:12 PM
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Bonjour Monsieurelec.,

Comme loin pour votre foret appuient le moteur vous peut me donner l'enseigne infomation je peux avoir une certaine idée avec cela.

Je sais que le contrôleur DC du moteur travaillera avec certains des moteurs universels mais le règlement de vitesse n'est pas très serré si attendez-vous à un certain diffrence sur la vitesse quand vous y mettez la charge.


As far for your drill press motor can you give me the nameplate infomation I may have some idea with it.

I know the DC motor controller will work with some of the universal motors but the speed regulation is not very tight so expect some diffrence on the speed when you put the load on it


Merci,
Marc
 
  #10  
Old 04-16-11, 04:01 PM
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Exclamation

Thank you guys for your replies!

I have found a way to slow down and then cut the motor.
It's a patent made in 1972 (then not yesterday).
It's just the first step because the guy used two switches (on,off) and put one RC and the stator in parallel and followed by a rectifier which work only when the switches are off to put DC in the brushes of the rotor.


I'll try it but I don't want to break it because for the sizing of the components I'll try it in a haphazardly way, if somebody got some hints?

Later i will replace the switches by some electronicals commutations componants (Mos of bipolar).

@telecom guy:
thank you for this hint and the schema kind of looks like what you describe but I have to keep it inside the tool to have a totally autonomous system(hope its possible)

@Mark:
ca fait du bien de mettre un peu de français sur le forum.
merci pour m'orienter vers le DC controller mais j'espere que ce schéma va m'aider et être une solution définitive.
Désolé je n'ai pas la plaque mais je sais que c'est un moteur de perçeuse très commun (1500W,8.5A) qui monte au max a 12,13A).
Donc j'espere que le materiel pourra le freiner.

Thanks
 
  #11  
Old 04-16-11, 04:17 PM
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I've tried to put the scheme but it didn't work so if you want to see what I found here is the adress:
DYNAMIC BRAKING FOR UNIVERSAL MOTORS
thank you
 
  #12  
Old 04-17-11, 03:20 AM
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Bonjour Monsieurelec.,

Donnez-moi un jour ou deux j'inventerai la réponse que vous cherchez.

( Give me a day or two I will come up the answer you are looking for.)

Merci,
Marc
 
  #13  
Old 04-17-11, 05:50 AM
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Merci
j'essaierai de mon coté les premières valeurs que je penserai de sécurité
 
  #14  
Old 04-17-11, 09:26 PM
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Bonjour Monsieurelec .,

J'ai oublié de vous demander cette question est ce foret appuient conduit-on la ceinture de moteur le mécanisme conduit ou que ? La raison pourquoi dû je peux le dispositif de freinant approprié inventé capable de taille.


(I forgot to ask you this question is this drill press motor is belt driven or gear driven or what? the reason why due I can able come up with proper sized braking device.)

Merci,
Marc
 
  #15  
Old 04-18-11, 02:01 AM
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Bonjour Mark,
It's not a drill press, its a normal drill with an universal motor.
Like this one:
Bien utiliser sa perceuse

Mercin de te pencher la dessus
 
  #16  
Old 04-19-11, 03:42 AM
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Bonjour Monsieurelec.,

Oh wow., Je n'ai pas y pensent pendant longtemps. Je verrai ce que je peux inventer quelque chose pour vous.

(oh wow I haven't think about it for very long time. I will see what I can come up with something for you.)

Merci,
Marc
 
  #17  
Old 01-18-12, 11:11 AM
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Hello Monsieurelec,
Would you mind also translating your french sentences to English, as Marc has done, so that others reading this forum can also understand what you are saying, and perhaps benefit?
Thank you.
 
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