I am trying to find Lf (field inductance), Rf(field resistance) and Laf(mutual inductance) values of my PM DC machine. I read quite some books and can not find an answer (I am not in this tech area). Anyone know how to do it? Thanks
Um, does the "PM" signify that the field is permanent magnet?
Those parameters do not exist in a Permanent Magnet machine because there is no field winding. What do you want those parameters for? Or, is this a trick question on a test or something? Bob
: ) That's not a trick question. Let me detail the situation: I have a PM DC motor at hand; while I am trying to simulate it in Matlab/Simulink. Simulink provides a toolbox that contains quite some electric machines. Unfortunately,there's no PM DC motor model provided. So, I want to use the model for seperately excited DC motor instead. That model requires Lf (field inductance), Rf(field resistance) and Laf(mutual inductance) values. That's the story.
Any simulation will be somewhat unrealistic if a non-existant coil is entering into the calculations. You can fudge some numbers like Lf=1H, Rf=1k and something for mutual inductance, what, I don't know. But what you really want to know and the program should take into consideration is the flux density in the gap, Bg. If you actually have the motor, what do you want to simulate it for? Just measure what the motor does, speed-torque curve, etc. The actual device is the ultimate analog computer and should need no simulation. Every parameter of a motor is directly measureable. Bob
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