Motor as generator at low rpm high torque??
Motor as generator at low rpm high torque??
(OP)
Hello all,
I am having trouble finding a motor that can be used to power up a propeller to about 12 rpm then shut off and act as a generator with the propeller being driven by an underwater current. The obvious problem here is though we have a lot of torque, what motor can generate any significant amount of power at that low rpm? To make it even harder the motor must be able to fit in a nine inch in diameter pressure vessel. We are trying to avoid large ratio gears as much as possible to minimize loss. We are currently looking at testing a DC motor,Stepper motor, and a DC brushless to check for efficiency and amount of power produced. Has anyone ever delt with motors in a similar application and can give any suggestions?
I am having trouble finding a motor that can be used to power up a propeller to about 12 rpm then shut off and act as a generator with the propeller being driven by an underwater current. The obvious problem here is though we have a lot of torque, what motor can generate any significant amount of power at that low rpm? To make it even harder the motor must be able to fit in a nine inch in diameter pressure vessel. We are trying to avoid large ratio gears as much as possible to minimize loss. We are currently looking at testing a DC motor,Stepper motor, and a DC brushless to check for efficiency and amount of power produced. Has anyone ever delt with motors in a similar application and can give any suggestions?





RE: Motor as generator at low rpm high torque??
They generally run at pretty high RPMs. The short coming of all this is that in the ocean there are some really, seriously, large fish that will successfully attack them on a regular basis.
Are you talking large? What size propellor? How many horsepower?
RE: Motor as generator at low rpm high torque??
RE: Motor as generator at low rpm high torque??
The energy you can extract from a motor is directly related to the speed you turn it. A couple of RPM is very hard to get anything from. I don't think you can do it. You could, but you would need a very strange motor with dozens of poles which kinda makes the motor think it's turning a lot faster. But lots of poles also makes the motor's diameter explode rapidly.
In my opinion you need gears. That said since you ars sub 1HP they can be very light cogged belts like you find inside a desktop printer. They are efficient and make tight bends without a lot of energy loss.
Also because you are sub 1HP you can actually use a small high performance permanant magnet motor as your generator.
They are only 1-2 inches in dia.
I'll hunt up a recent post that had this same discussion.
Meanwhile check this:
http://www
RE: Motor as generator at low rpm high torque??
Had a simular discussion except for the fluid involved.
Not a lot of difference.
RE: Motor as generator at low rpm high torque??
RE: Motor as generator at low rpm high torque??
Check out TowerHobbies. You need to dig around a little.
This motor is 200W. See what else you can find.
Go down the page to R/C Electric motors. AND SPECIFICALLY
R/C Electric Motors - Aircraft
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Some of the listings say a lot about a motor, others say nada.
http://
This is the kind of thing I was refering to. And from a prototype point of view these places are way easier to deal with.
You could use more than one as a possibility too. Just stay away from the brushless as I don't think they will work as generators.
RE: Motor as generator at low rpm high torque??