# Dc Servo Motor MX-106TR(2) Modelling- Finding Motor Parameters by Calculation

#### Josef

Happy new year.

I was asked to model your motor, using MATLAB but however I do not have motor parameters.

I need the following parameters :

1. Inertia of motor armature
2. Motor torque constant
3. Backemf constant
4. Motor induction
5. Armature resistance
Using you performance graph available at your page, that’s my result:

1. Choosing Torque 1.20Nm, Current 0.8A, Efficiency 42% from the performance table
2. Assuming inductance of the armature are very small nearly zero, so backemf becomes voltage supplied - resistance x current armature, by that Ke=backemfvoltage/speed so ke=0.2681 v/rpm
3. By using the value chosen I found, the torque coefficient kt= torque/current =1.5Nm/A.
4. To find the inertia, I had to find the acceleration so, I rotate the motor at 41rpm during 30s so the acceleration is 0.002 rev/s2
5. Since this is equivalent to 1.20Nm torque so, Inertia J=1.20/0.0022 =54.05Nm/rev/s2
6. Since B viscous friction is very small assumed it to be 0,08
7. L (inductance) assumed to be 0.1
8. I measured R to be 2.44, devide by 2 , we have 1.22 ohms.

I need you to confirm that either my values or assumptions are make sense.

Thank you
Josef Neto