Transfer Function of DC Motor

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I do not see parameters like motor viscous friction constant for example
 

Depends on the data sheet completeness. Most important parameters are emf and torque constants. They can be derived from a good datasheet. Also friction constant from the no-load current. Rotor inertia and inductance are rarely specified and must be measured or estimated.
 

I have attached the image of DC motor datasheet. Could you please guide, how to calculate motor viscous friction constant ,electromotive force constant
 

Hi,

It's not a motor, it's a generator.

Klaus
 

No it's a motor (see item 20). Item 7 specifies the power supply.

The datasheet clarifies that the motor has among other features variable excitation and a compound winding, thus the simple DC motor model derived in the link in post #1 doesn't apply. Refer to an electrical machines text book for a detailed analysis.
 

Hi,

Indeed you are right. I misinterpreted the "generator" and "excitation" ...

Klaus
 

Yes, It is separately excited dc motor. Would viscous friction and emf depend on type of motor(simple or compound).
 

Sketch a complete equivalent circuit of the motor with all windings. You'll realize that there more parameters involved than with the simple PMDC motor analyzed in the post #1 link.

There are no parameters in the above datasheet that allow estimation of friction constant.
 

ok. Now one last question. I wanted to know the dimension normalization in a typical DC motor control system. For example inertia is usuallyt given in kg-m2 and speeds are usually rad/s. Can we subsititute these values as it is or any conversion is required?
 

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