Dc Motor

SIMULATION OF ARMATURE CONTROLLED DC MOTOR IN MATLAB/SIMULINK MODELLING V = ia R + L + Eb ……… (1) Taking La-Place Transform V ( s ) = I a ( s ) [ R + sL ] + Eb ( s )……… (2) Eb = Kbω dθ dt Eb ( s ) = Kb sθ ( s )……… (3) But ω =

Substitute (3) in (2) V ( s ) = I a ( s ) [ R + sL ] + Kb sθ ( s )……… (4) d 2θ

dθ + TL dt dt 2 Assuming load torque, TL = 0

T =J

+B

T = Kt ia Kt I a ( s ) = Js 2 + Bs I a ( s) =

Js 2 + Bs ……… (5) Kt

Substitute (5) in (4) Js 2 + Bs V ( s) = [ R + sL] + Kb sθ ( s) Kt Js 2 + Bs ) ( R + sL ) + Kb Kt s ( θ (s) V ( s) = Kt

Transfer function is

θ ( s) V (s)

θ ( s) V (s)

=

Kt

( Js2 + Bs ) ( R + sL ) + Kb Kt s Kt

=

k RB = 2 s (1 + τ m s ) (1 + τ s ) + Kb s s (1 + τ m s ) (1 + τ s ) + Kb 2 s

Fig. 1. DC motor model

M-file Ra=2.5 ; % resistance in ohms La=0.5000; % inductance in H J=0.01265; % inertia constant in kg-m^2 B=8.4e-4; % friction coefficient in Nm-s Kb=1.10089; % motor constant in Vs/rad PLOT COMMANDS plot(y(:,1), y(:,3)) title('RESPONSE ') ylabel('Speed (rpm)') xlabel('Time (s)')

SIMULATION RESULT

Melvin Koshy M.Tech College of Engineering, Trivandrum E-mail: [email protected]

SIMULATION OF FIELD CONTROLLED DC MOTOR IN MATLAB/SIMULINK vf = if Rf + Lf

di dt

Va = constant dω + Bω dt T = K f if T=J

Kf Transfer function

ω (s) v f (s)

= s2 +

Lf J BL f + R f J Lf J

s+

BR f Lf J