DC universal motor

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thierrylah
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DC universal motor




by thierrylah » 30/09/13, 01:24

Good evening,
Following my Project Rocket Stove I would need a circular saw on battery to cut the branches to measure directly in the woods.


For that I would like to supply direct current to my universal motor of my circular saw which currently works in alternating current 220V I would like to know if it is feasible in a reliable way and what would be the DC voltage which I should apply in a way what it spins at 4200 rpm

The motor is a 2000 W

The battery supply will be lithium (that of my electric ATV with trailer / workbench)

In trade it has Ryobi type solutions but I find it unfortunate the lack of power in the technical characteristics.

I also find that the batteries are expensive compared to the autonomy which gives me especially that that of my bike are cheaper and more versatile.

Thank you to everyone who can help me with this project

thierry
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crash
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by crash » 30/09/13, 09:47

As a general rule, it seems to me that this type of motor are DC motors but 50hz suitable for the domestic electrical network. To be able to use a battery as a source of energy, it will therefore be necessary to use an inverter between the battery and the motor. The inverter will convert 12v (DC) to 220v-50hz (AC). Pay attention to the maximum current demanded by the motor, otherwise there is a risk of gun damage to the inverter.

If you could provide us with more information on the engine (photo of the latter and that of the cartridge, this will better inform you.

Hoping to have been useful.
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by dirk pitt » 30/09/13, 11:41

no need for an inverter if it is a universal carbon motor. they work both alternately and continuously.
on the other hand the problem is the tension.
it should be supplied with 230V DC
another problem (of size) power and autonomy.
a 2000W saw will require a BIG battery.
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by elephant » 30/09/13, 11:46

Besides 230 V DC, it can be very dangerous, both in short circuit and electrocution.

I understand that you don't want to use a gasoline engine, but I really think that to solve your problem, it's a whim.
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by BobFuck » 30/09/13, 18:23

Walking around with a 230V battery could be expensive, heavy and dangerous.

In addition a universal motor has a fairly rotten efficiency (like 30-40%) while a brushed DC motor (the classic of the portable electric on battery) will be more in the 60-80%, therefore twice the cutting on the same battery.

Cutting branches with a circular saw, it also seems to me a great way to amputate ...

anti amputation chainsaw:
http://www.youtube.com/watch?v=qkp08PEhhno
(it doesn't seem to cut very quickly ...)

special amputation chainsaw:
http://www.youtube.com/watch?v=u17ll043Ld8

otherwise you have:

- electric hand
- arm saw

and for small branches (like 3cm), ratchet pruning shears (or electric for girls)

Personally I would take a thermal chainsaw, or an arm saw (just to do a little sport).
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by chatelot16 » 30/09/13, 19:30

a universal motor works well in direct current but not 220V, it's too much

the stator inductance limits the current at 50Hz, continuously a lower voltage is required

I already used a 220V drill on a 110V battery, it gave it about the same power as in 220V but with some problem:

direct current is more difficult to cut than the alternative: the switch ends up welding! the drill no longer stops!

other drawback: in dc the universal motor has a less stable speed than in 50 Hz: when empty it takes off and turns at a huge speed
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by thierrylah » 30/09/13, 23:41

thank you for your answers,

crash @ I preferred to avoid inverter !!

The motor has 2 coals, the rotor and the stator are wound, I deduced that it is a universal motor here is some photo

Image

Image

Image

My Rocket Stove works with branches of Ø 5cm and length of 30 cm, I prefer to carve them on site to reduce the size and facilitate transport (electric mountain bike + trailer / workbench)

I work in the building I find it more practical to cut the wood with a circular saw mount upside down on an iron plate as in this photo

Image

I live in Italy in a mountain area ([url = http: //mw2.google.com/mw-panoramio/photos/medium/73386190.jpg] Turania [url]) very supplied with wood and not always easy to access (mule track) that's why I chose mountain biking as a means of transport

chatelot16 @
Isn't there a way to prevent that switch from soda?

That the motor is running dry is it not possible to manage it with a voltage converter?
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thierrylah
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by thierrylah » 30/09/13, 23:46

thank you for your answers,

crash @ I preferred to avoid inverter !!

The motor has 2 coals, the rotor and the stator are wound, I deduced that it is a universal motor here is some photo

Image

Image

Image

My Rocket Stove works with branches of Ø 5cm and length of 30 cm, I prefer to carve them on site to reduce the size and facilitate transport (electric mountain bike + trailer / workbench)

I work in the building I find it more practical to cut the wood with a circular saw mount upside down on an iron plate as in this photo

Image

I live in Italy in a mountain area Turania very supplied with wood and not always easy to access (mule track) that's why I chose mountain biking as a means of transport

chatelot16 @
Isn't there a way to prevent that switch from soda?

That the motor is running dry is it not possible to manage it with a voltage converter?
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by chatelot16 » 01/10/13, 00:01

to avoid boiling the switch it must be replaced by a contactor suitable for direct current

DC contactors have large arc blowing systems much more bulky than at 50Hz

to avoid empty embalming would require a voltage variator is a servo which reduces the voltage when the speed increases, and where to find a variator powered by continuous 220v?

while 220V 50Hz continuous converter are cheap and high efficiency current stuff

if it is only for the circular saw a cheap model pseudo sinus which is a square tension is enough, but it is better to buy a true sinus, being able to be used for more thing

what would be your source of direct current?

attention to the electrical network on high voltage battery: in the event of a short circuit the ordinary fuse for 50Hz does not have a sufficient breaking capacity: the electric arc passes through and the current continues to flow ... ditto for the circuit breaker ... all wiring habits are to be revised
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by chatelot16 » 01/10/13, 01:31

cut the small branches in the woods when the wood cutters are finished, I already did it to heat me for whole winters

the most effective way I found is the chopping block and the ax

no electricity or petrol and faster
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