Calculating current from a permanent magnetic DC Motor

[Vauxdvihl]

Hi friends,

i have a permanent magnetic DC Motor and i want to calculate the current flowing through the motor.

The motor is driven by a pulse voltage (pulse width varies, frequency is close).

I have nothing found on the web.
May be that somebody have done it before.

Thank you very much

Regards

 

[jorgito]

Hello,
1.- You can set up a electromechanical model of your motor. Get L, R and Kv (speed constant) an feed it with your power pulses.

2.- You can measure your motor's Kv and remember that *IN COHERENT UNITS* Kv is aproximately numericaly equal to Ki (torque constant) wich is, usualy much difficult to measure.

3.- No name plate in your motor?

I hope this help
Regards

 

[Vauxdvihl]

Thanks for your answer !

Do you have some papers about the first point ??

Regards

 

[jorgito]

Sorry, no papers....
Maybe using Google you can get something usefull.
I've done it some 20 years ago using SPICE and CSMP running in a IBM370.
Any decent control systems book will give you a mathematical model for a DC motor.
best regards

 

[flatulent]

another method

Another round about method would be to use the efficiency of the motor. Mecanical power out = efficiency x electrical power in. The efficiency should be one of the rated parameters from the data sheet.

 

[Vauxdvihl]

OK thanks a lot !

I will try the ways you've posted

Thanks

Regards