Hi everyone,

I have a DC motor that I want to use as a generator, the generator is connected to a wind turbine, however I would want to control the input speed on the generator. I have seen several posts saying that you have to load the generator and the speed will decrease, however if I measure the voltage output of the generator at 500 rpm it is 2.5V with no load, and right after i add a resistor the voltage drops to 0.1V... any help would be appreciated.

Thank you in advance

 

hi.
Please post details of the motor type, Part No: etc..
E

 

hi.
Please post details of the motor type, Part No: etc..
E

HRS550S-12670
DC12V-AT944
I could not find any datasheet for it.

 

hi,
Is it this type.?
https://gimsonrobotics.co.uk/catego...s/hrs-550s-dc-36mm-motor-12v-and-18v-versions

E

 

hi,
Is it this type.?
https://gimsonrobotics.co.uk/catego...s/hrs-550s-dc-36mm-motor-12v-and-18v-versions

E

yes this is it

 

What power are you hoping to produce?
And why do you need to control the speed? Surly the aim of a wind generator would be to get the most power you can out of it?
The motor you have chosen may not be the best to use.

and right after i add a resistor the voltage drops to 0.1V

What was the resistor value? That is pretty important to determine if this motor is ok for the job.
And as you increase the load current, the speed will decrease. The energy to produce the current has to come from somewhere.
For a toy level wind generator, I had an old stepper motor driving a 3 phase diode bridge. It was a garden ornament, just running LEDs.
Fisher and Paykel washing machine motors have well been used for significant power generators, wind, water and motor driven.

 

I do want to use it for wind turbine control, the reason i used this motor is simply because due to the current situation it is the only one available that rotates higher than 1000 rpm. That being said, the resistor value is between 1ohm to 20k ohm. Any suggestions for motors and resistor values for a max rotation of 1000 rpm?

 

If your output goes to 0.1V with a 20K resistor on it, you need to find a better motor.

Still, I do not know why you need to limit the RPM.
And no one can tell you what resistor value to uses as it is just not that easy. There are just too many variables.
If you do need to limit the RPM for some reason, first you will have to be able to read the RPM. Then, some controller, like an Arduino, could switch load resistors, or as this is a low powered device, just drive a power transistor to load the output down to limit the speed.
You may find though, even with a short on the motor, in strong winds, the speed may exceed you wanted RPM.

Can you please explain why you need to limit the RPM?????

And it is really worth while finding a brushless motor, like a stepper or BLDC motor as there is a lot less to wear out.
And you will get more output at lower speed with one of those.

 

If your output goes to 0.1V with a 20K resistor on it, you need to find a better motor.

Still, I do not know why you need to limit the RPM.
And no one can tell you what resistor value to uses as it is just not that easy. There are just too many variables.
If you do need to limit the RPM for some reason, first you will have to be able to read the RPM. Then, some controller, like an Arduino, could switch load resistors, or as this is a low powered device, just drive a power transistor to load the output down to limit the speed.
You may find though, even with a short on the motor, in strong winds, the speed may exceed you wanted RPM.

Can you please explain why you need to limit the RPM?????

And it is really worth while finding a brushless motor, like a stepper or BLDC motor as there is a lot less to wear out.
And you will get more output at lower speed with one of those.

the reason to limit rpm is to be able to find different torque values at different speeds so I can obtain a graph of Torque vs Tip Speed Ratio for a constant wind speed.

 

the reason to limit rpm is to be able to find different torque values at different speeds so I can obtain a graph of Torque vs Tip Speed Ratio for a constant wind speed.

And just where is this "constant wind speed" located? In my area the wind varies in speed and direction almost constantly. To find torque and the horsepower from it why not a "prony brake"? https://en.wikipedia.org/wiki/Prony_brake A prony brake is the basis of a dynamometer just old school.

Have you seen this or any of the other hits on Google for wind generator torque? https://www.hbm.com/en/3108/torque-measurement-in-wind-turbines/

 

And just where is this "constant wind speed" located? In my area the wind varies in speed and direction almost constantly. To find torque and the horsepower from it why not a "prony brake"? https://en.wikipedia.org/wiki/Prony_brake A prony brake is the basis of a dynamometer just old school.

Have you seen this or any of the other hits on Google for wind generator torque? https://www.hbm.com/en/3108/torque-measurement-in-wind-turbines/

the tests are done in a wind tunnel thats why you can get a constant wind speed. Now the turbine yields 0.05 N.m, and such torque sensors are way to expensive... so thats why