Inductance of CIMs

[Joe Johnson]

Originally Posted by phrontist

As I understand it, a motor with a large inductance will respond... sluggishly as the magnetic feild builds. In the CIMs the effect is not terribly dramatic.

That said, the inductance needed to be included in this mathematical model, I'm told, because the power curve only provides insight to the motors behavior at a given fixed speed. It does not address how the motor responds as it accelerates.

After some futzing about with a function generator and oscilloscope our alumnus found the result he was after.

I am glad you got the data you were seeking but I am not sure it will explain the dynamic behavior you are trying to model.

In almost every case (and perhaps EVERY case in a FIRST application), the time constant of the motor's inductance is at least an order of magnitude faster than the mechanical time constant of the system.

Bottom line, the primary reason that the steady state speed-torque curves do not predict dynamic behavior of a motor+arm or a motor+robot is not that the motor current is hindered by the inductance of the motor windings but rather that the rotational velocity of the motor is hindered by the effective rotational mass of the system.

Joe J.