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Home Wind Turbine for electricity

Aloittaja Ron, 08.06.15 - klo:02:49

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Ron

Kremmen - what do you think of Cartti's idea of using a washing machine motor? 
It is a motor and as such taking electricity power IN. How do I get from it Electricity power OUT?

Ron

Thanks Cartti, but as a motor it takes electricity power in. How do I get from it electricity power OUT?

Kremmen

Lainaus käyttäjältä: Ron - 10.06.15 - klo:19:21
Kremmen - what do you think of Cartti's idea of using a washing machine motor? 
It is a motor and as such taking electricity power IN. How do I get from it Electricity power OUT?
Basically every motor is also a generator. you push electricity in and you get torque and rpm out. You put those in and out come voltage and current.
The motor Cartti linked would probably work nicely. It has a permanent magnet excitation so will not consume parasitic power. Just turn the shaft and you will see a voltage at the stator connections. All motors have certain characteristic constants such as rpm per volt or conversely volts per rpm if used as a generator. Withing reasonable limits you need to find a motor that produces voltages that you can use. The washing machine motor could be direct drive, i.e. it is connected directly to the drum with 1:1 "gear ratio". That means it will turn roughly somer 1600 rpm at 230 VAC (or whatever the spin cycle rpm is for the particular washing machine). If you turn the shaft at the same 1600 rpm, you will get more or less the same 230VAC out of the "generator".

Nothing sings like a kilovolt
Dr W. Bishop

Kremmen

#18
To expand my previous post a bit:

An electric machine is a converter that changes voltage and current to rotation and torque, or the other way around.
If you consider an ideal DC motor, then its speed of rotation is directly proportional to the armature voltage. Likewise its shaft torque is directly proportional to the armature current.
Since it is an ideal machine (that does not exist in real life) there are no losses anywhere. The motor will turn without consuming current, and any current through the armature will not cause a voltage loss. That being the case the ideal machine is a perfect converter between electrical and mechanical power. It is important to note that the conversion can happen in either direction - the machine won't care.

Example: An ideal DC machine is used as a motor. Let's assume its motor constant Kv is 10 rpm/volt to make calculations easy. That means that for every volt of armature voltage the shaft will turn an additional 10 rpm more.
So say we supply 100V of armature voltage; what happens? The armature and shaft accelerate until the back EMF of the motor is equal to the supply voltage. The back EMF (ElectroMotor Force or in some texts ElectroMotive Force) is the voltage produced by the machine when it turns. When the supply voltage exactly equals the back EMF the shaft speed has achieved final speed and accelerates no more. Now the motor is in balance and will continue turning until further notice.
Next we close a clutch connected to the motor shaft and start turning a load. Assume the load is something like a propeller so that the faster it turns the more torque the motor must provide. Now you can visualize that the load causes the motor speed to go down and the back EMF no longer matches the supply voltage. Since the armature resistance of an ideal machine is exactly zero, a basically infinite current will start to circulate in the armature winding. This current will induce a torque in the machine shaft and that torque will accelerate the shaft until the back EMF again matches the supply voltage. When the machine is again in balance, an armature current will circulate such that it exactly produces the torque needed to turn the shaft at the speed where back EMF matches supply voltage. This current depends on another machine constant, the torque constant Kt giving Nm / ampere.
The important point is that in an ideal machine the supply voltage and that only, determines the shaft speed. Similarly, the armature current and that only, determines the shaft torque. Also, the ideal machine is a perfect converter so that power in always equals power out. Thus the electric power in watts (==volts * amps) is always equal to the mechanical power in watts (==torque * angular speed, expressed in newtonmeters * radians/second).
In a practical machine there are all kinds of losses that cause the voltage and current to interfere but those can be compensated or ignored.

Now, you can turn all of the above around and use the machine to convert shaft speed to voltage and shaft torque to current. Of course to get current you need an electrical load just as you need a mechanical load to create torque. In a wind generator the load is usually controlled by a Power Point Controller that monitors the shaft speed (due to wind) and based on a model of the windmill tries to maximize the extracted power by causing the generator to see a heavier or lighter load. If this process is optimized, the controller is called a Maximum Power Point Tracking Controller or MPPT. (Caution: lots of the cheap Chinese MPPT controllers are not. They just advertise MPPT but don't actually implement a working MPPT algorithm. It is not trivial to do.)

Nothing sings like a kilovolt
Dr W. Bishop

TeacDance

suoraveto pesukoneen moottorista saa ihan hyvän generaattorin itse kokeilimme muutama vuosi sitten moista ja vieläkin pyörii ja tuottaa sähköä.

Suoraveto koneen moottorin testausta sorvilla
https://www.youtube.com/watch?v=3SpI7v6Mtxg

Käämit piti vaan kytkeä toisin siitä löytyy netistä suoraan kytkentä miten ne kannattaa että kierroksia ei tartte olla niin paljoa.
_________________
Tero Koskela
Ylivieska

YouTube

Kremmen

This link has some info about washing machine motors as generators like TeacDance's version. Also other potentially useful info.
Nothing sings like a kilovolt
Dr W. Bishop

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