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| Is this a valid method to measure the inductance of a brushed DC motor? |
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| fishandchips:
Thanks. In this case, do you think the methods presented in: http://www.dos4ever.com/inductor/inductor.html and https://electronics.stackexchange.com/questions/182116/whats-the-easy-way-to-measure-a-dc-hobby-motors-inductance may not be suitable to measure the inductance of a 12V DC motor? I am trying to get the inductance for modelling in simulink. Is it better to get a LCR meter instead? I am trying to save some money but if it is more accurate and easier to get the inductance using a LCR meter, maybe I have to buy it. |
| qibeike:
Hey, did you find a way to measure the inductance of the motor? I'm trying to model in simulink an electric vehicle too and I need the internal inductance of the motor. Thanks in advance. |
| rstofer:
The method is valid even if the frequency seems over the top. Measure the DC resistance of the winding. Then add a series resistor that will make the motor + resistor value match the generator output - probably 50 Ohms. Apply a signal, perhaps a couple of volts and measure the current by reading the voltage across the external resistor. From the voltage and current you get total impedance. You know the two resistances (motor + external resistor in series) so all you need to do is get the inductive reactance and then solve for L which is a function of frequency. http://support.ctc-control.com/customer/elearning/younkin/motorParameters.pdf Page 4 talks about it... I'm not sure if the numbers will make any sense. Try a few frequencies and see how it turns out. When I was playing with a DC motor simulation, I just picked 80 uH and called it good. It's far more important that your model tracks the physical constants of the motor. These may need to be measured with a tachometer, voltmeter and ammeter. https://web.stanford.edu/class/me161/labs/Lab06MotorConstants.pdf |
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