How to obtain the parameters of DC motors?

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SUMMARY

This discussion focuses on obtaining key parameters of a Tamiya geared DC motor, specifically resistance, inductance, Back EMF constant, torque constant, and voltage caused by Back EMF under higher voltage conditions. The manufacturer only provides limited data, including torque constant and dynamic resistance at recommended voltage levels. To accurately measure these parameters, a test bench equipped with a sensitive dynamometer, tachometer, voltage and current meters, an oscilloscope, and a controllable power source is essential. Caution is advised when supplying voltage above the recommended level to avoid damaging the motor.

PREREQUISITES
  • Understanding of DC motor parameters such as Back EMF constant and torque constant.
  • Familiarity with measurement tools like dynamometers and oscilloscopes.
  • Knowledge of electrical concepts including voltage, current, and resistance.
  • Experience with data logging and experiment control using a PC.
NEXT STEPS
  • Research methods to measure DC motor inductance accurately.
  • Learn how to set up a test bench for motor parameter measurement.
  • Explore the use of data logging software for automated experiment control.
  • Investigate the effects of over-voltage on DC motor performance and longevity.
USEFUL FOR

Engineers, hobbyists, and researchers involved in motor control, robotics, and electrical engineering who require detailed performance parameters for DC motors.

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Hello, I appreciate if somebody could help me to resolve this. I bought a geared DC motor from a store. I would like to obtain the following information: Resistance, Inductance, Back EMF constant, torque constant, and the voltage caused by Back EMF when the motor is supplied by a voltage input higher than the recommended one. What experiments do you recommend to obtain these values? Do I need fancy equipment to get these values by experiments?

Even I asked the company, they can only provide the following information (at the recommended voltage): torque constant, Back EMF constant, Dynamic Resistance and Motor Regulation. The guy asked the manufacturer. He said that these are all he can get and he has no idea what they mean. if I supply 4V higher than the recommended input voltage, will these provided values change a lot? Which parameter(s) stay the same?

Thank you
 
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Any identifying information on the motor - maker - product number ?
 
Just a Tamiya toys motor. The manufacturer does not seem to want to provide all the information.
 
They only give the gear ratio. I need the parameters I mentioned for modelling. Any good approach to measure the values?
 
Thanks but not sufficient to model it. I need the parameters mentioned in the original post.
 
Well I can't really see why you need any of these values but if you want to experiment then you need to build a test bench .

There would have to be at minimum some variety of very sensitive dynamometer , a tachometer , voltage and current meters , an oscilloscope and a finely controllable power source .

Problem is that any transient events like run up time to speed are going to take place so quickly that you won't be able to take reliable readings manually .

Probably best to use a PC to control the experiment and log all the data automatically .

What do you want to use the motor for ?
 
Last edited:
Applying excess voltage may well result in excess current and a burnt out motor. Be a shame to burn up your motor just as you get the parameters you want.
 

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