Is Ex-Treadmill DC Motor is good for wind turbine ?

Thread Starter

meowsoft

Joined Feb 27, 2021
471
Is Ex-Treadmill DC Motor is good for wind turbine ?
3HP 220v DC, 12.8a, 3500RPM, do you think that is good ?
Output expected is about 12v-36v DC
Also how many wind speed I need to rotate that turbines for about 572 rotation per minute ?
Please give advice....
 

MaxHeadRoom

Joined Jul 18, 2013
23,649
DC motor makes a good generator.
It will generate approx. 220vdc at 3500rpm
So it should be fairly easy to rotate at 570.
The wind speed required will depend on load and impeller design.
 

Thread Starter

meowsoft

Joined Feb 27, 2021
471
DC motor makes a good generator.
It will generate approx. 220vdc at 3500rpm
So it should be fairly easy to rotate at 570.
The wind speed required will depend on load and impeller design.
Do you think that motor is good ?, and it is good to connect load directly with constant power buck converter ?, load is 12v DC and 24v DC
 

MisterBill2

Joined Jan 23, 2018
9,308
A permanent magnet DC motor can certainly serve as a Dc generator. That much is completely true. But most treadmill motors are used in a dry environment, while usually windmills are subject to wet weather. So keeping water out of the motor will require some effort.
A much bigger concern is the voltage/current ratio, especially relative to the 12 volt and 24 volt application. If this is a wound-field motor then the control scheme will need to be a bit different. And we have no information as to which type of motor it is. So the very first question is about the motor field? Wound with field coils? or permanent magnet fields?
 

Externet

Joined Nov 29, 2005
1,662
Will likely need gearing/pulleys to multiply rpm to turn the generator at a higher speed. For serious use, implement brake, can be by pulling a string from ground level.
 

Thread Starter

meowsoft

Joined Feb 27, 2021
471
A permanent magnet DC motor can certainly serve as a Dc generator. That much is completely true. But most treadmill motors are used in a dry environment, while usually windmills are subject to wet weather. So keeping water out of the motor will require some effort.
A much bigger concern is the voltage/current ratio, especially relative to the 12 volt and 24 volt application. If this is a wound-field motor then the control scheme will need to be a bit different. And we have no information as to which type of motor it is. So the very first question is about the motor field? Wound with field coils? or permanent magnet fields?
That is 220v DC not 12 or 24
 

MisterBill2

Joined Jan 23, 2018
9,308
I know that the original application rating is 220 volts, and that the desired output in the new application is 12 to 36 volts, from post #1. And I am presuming hat the specified 572 RPM is the speed calculated to deliver that lower voltage. So while the 12.8 amps current will not be an isue, the actual power will be quite a bit less than what the 3HP rating will suggest. And still no answer about if itis a permanent magnet motor or a wound field motor. That matters because controlling the output of a wound-field generator is rather easy and simple, while controlling the output from a permanent magnet generator requires a lot more external circuitry, such as a switching mode regulated inverter.
 

Thread Starter

meowsoft

Joined Feb 27, 2021
471
I know that the original application rating is 220 volts, and that the desired output in the new application is 12 to 36 volts, from post #1. And I am presuming hat the specified 572 RPM is the speed calculated to deliver that lower voltage. So while the 12.8 amps current will not be an isue, the actual power will be quite a bit less than what the 3HP rating will suggest. And still no answer about if itis a permanent magnet motor or a wound field motor. That matters because controlling the output of a wound-field generator is rather easy and simple, while controlling the output from a permanent magnet generator requires a lot more external circuitry, such as a switching mode regulated inverter.
But question it is that better than AC generator ?!
 

MisterBill2

Joined Jan 23, 2018
9,308
Certainly the are quite different, AC voltages can be changed with a transformer, which is very simple and convenient, but transformers can be quite expensive to purchase, and in the larger capacities they are both large and heavy. A free treadmill motor is much less costly, and depending on the use of the output it may be much easier to use. If the intended application is charging a storage battery system, then using a free generator and a self-built regulator will be the least expensive way to go.
With a 12 volt output and 12 amps current the power level will be within the realms of an easily constructed switchmode power package. And if you are able to construct a turbine blade able to spin the motor at the 3500 RPM speed it could work to feed the resulting 220 volts directly into the input DC point of a standard switcher power supply, and get whatever voltage you want.
So which is the better choice, AC or DC, depends on a number of things.
 

MisterBill2

Joined Jan 23, 2018
9,308
At one point one of my friends investigated converting a Mopar alternator into a PM alternator by replacing the field coil in the armature with a ceramic magnet. The challenge is getting the armature to come apart so that the coil can be replaced with the magnet. I wonder if others have tried that with alternators that could be more easily modified.
 

Thread Starter

meowsoft

Joined Feb 27, 2021
471
@MisterBill2 do you know to make 3 phase step up transformer DIY ?, how about winding configuration ?, I want to make from small to step up 12v/20.8v to 220v/380v, but start from only about 1A secondary
 

Thread Starter

meowsoft

Joined Feb 27, 2021
471
@MisterBill2 do you know to make 3 phase step up transformer DIY ?, how about winding configuration ?, I want to make from small to step up 12v/20.8v to 220v/380v, but start from only about 1A secondary
It is right for 35 turn for 12v primary and 641 turn for secondary ?, and what's wire size I need ?, is 3.0mm for primary and only 0.4mm for secondary is right ?
12v/20.8v 18amp (per phase winding)
220v/380v 1amp (per phase winding)
 

MisterBill2

Joined Jan 23, 2018
9,308
The afe and imple way to achieve a 3-phase transformation is three separate transformers. Then connect them in either a "wye" or a delta arrangement. For the wire size, first find power and voltage, then determine the current. That will determine the wire diameter. There is much literature available about transformer design and building, but note that part of that is aimed at the minimum cost direction rather than maximum efficiency.
 
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