DC Motor Modelling (PDF )

Running head: DC MOTOR MODELLING AND CONTROL
DC MOTOR MODELLING AND CONTROL
Name of the Student
Name of the University
Author Note

DC MOTOR MODELLING AND CONTROL1
Section A: DC Motor Modelling
1. The equivalent circuit diagram of separately excited DC motor is given below.
The field resistance Rf = 75 Ω.
Field inductance Lf = 50 H
Back emf constant Ke = 0.5
J = moment of inertia of drive = 0.2 kgm^2
B = frictional coefficient of drive system = 0.067 kgm^2/s
Here, Va = armature voltage (V)
Ia = armature current (A)
Ea = back EMF produced at the Armature
Vf = DC field voltage and If = current (A)
Te = electrical drive torque and Tl = load torques (Nm)
ω = drive speed in rads/sec.

DC MOTOR MODELLING AND CONTROL2
Ra = armature resistance, La = armature inductance, Rf = Field resistance, Lf = field
inductance.
Hence, by using the KVL analysis
Va = V(Ra) + V(La) + Ea
Va = Ia*Ra + Ia*(dIa/dt) + Ea.
Now, the value of Ra = (2*(xyz/999) + 1). Here, ‘xyz’ is 304.
Hence, Ra = 2*304/999 + 1 = 1.6086 Ω.
2. Now, the Back emf of the DC motor is given by,
Ea = Ke*If*ω.
Now, this is built in Simulink as given below.
Here, the field current If and drive speed w are maintained at 0 and field voltage is
maintained at 100 volt by a controlled voltage source.

DC MOTOR MODELLING AND CONTROL3
Plot of field current:
The dc motor parameters are entered inside the DC machine block.
Plot of armature current: