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ERPM, the RPM on the motor does not change

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hopeingod
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ERPM, the RPM on the motor does not change

My name is Oleksandr, I live in Ukraine. I am 35 years old, I have cerebral palsy and I use an electric wheelchair. I want to replace the DC motors of the collector type on the baldes in the electric cart. For this, I bought the controllers and I want to increase the revolutions on the motors because the kv is quite low, a little more than two/ When changing the ERPM, the RPM on the motor does not change, it changes depending on the voltage, so please advise. how can i change RPM programatically via vesc tool. thank you

electricfox
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Hello Oleksandr, not really sure what you are asking for exactly. If you want the existing motors to spin faster you will need higher voltage. You can not change the ERPM by VESC by changing ERPM Limit in this case, except you are using field weakening. Field weakening is not usable for all kinds of motors and you have to take care of some settings and know what you are doing, especially when the vehicle carries you. You are using a brushless motor right?

hopeingod
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Good day

Thanks for the answer.

I'm sorry that maybe I didn't ask the question correctly, I don't have very good knowledge of electrical engineering.

My electric cart has a collector motor that is now broken. With such characteristics, 24 V, 3000 rpm. The electric motor transmits rotation to the wheel through a gearbox. According to the recommendation of my electronics acquaintance, it is better to replace the collector motor with a collector-less (bldc) controller, the best option is VESC. .

I bought a wesk controller and asked a friend to test it for suitability for motor control and the possibility of putting it on an electric wheelchair.

We tested the controller with the 8318 kv120 engine. When measuring kV, we got 100 kV instead of KV-120 declared by the manufacturer. That is, 20% less than declared by the manufacturer.

I have not yet bought a motor for an electric cart. If you buy a bloods motor with characteristics of 24 V and 3000 rpm, then with such settings of the controller, the maximum revolutions will be 2500 rpm.. And this will affect the maximum speed on the wheelchair. I use maximum speed on a flat road.

Therefore, the question arises how to programmatically achieve the kV declared in the technical characteristics of the engine, without weakening the magnetic field. What settings to pay attention to?

I will be grateful if you send information on the optimal settings of the controller for the bloods engine.

I am sending videos and photos of kV measurements and our calculations.

 

https://www.youtube.com/shorts/7gMkNXgqiqQ

Thank you for the answer.

electricfox
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Ok so you want to move from an brushed to an brushless motor. With using FOC (compared to RC Model ESC's) its typical to loose some percentage of max speed, also because VESC uses max 95% cuty cycle. Manufacturers specify values they can not hold. Your test was without load, so under load you will loose even more RPM, not only KV rating, but also voltage sag of your battery. As long as you don`t hit the max ERPM Limit in VESctool (standart 100kERPM) the RPM you achieved is correct and you can not change it to higher RPM. You will need a different motor or higher voltage.

hopeingod
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Good day again. We thank you for your prompt response. Now it is clear to us that it is necessary to order a motor with higher revolutions or to change the voltage. Max ERPM Limit remains unclear. max ERPM Limit is a software limit, or a controller, or an engine limit?
In our controller ERPM is 150,000.

electricfox
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Read here about ERPM: https://vesc-project.com/node/183

hopeingod
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Thanks for the answer. After carefully reading the information on the link you sent me, everything is clear. Only I could not find where the limit parameter is changed in the program. Because the Vesc-Tool 6_ERPM Limit picture does not open. Please tell me where the ERPM limit changes ?