Page 567 - The Mechatronics Handbook

0066_Frame_C20 Page 37 Wednesday, January 9, 2002 5:49 PM

Applied voltage, V
Speed
EMF Speed
Torque
E
Torque

Armature current

FIGURE 20.59 The shunt-wound motor load characteristics.

Torque

Speed

FIGURE 20.60 The shunt-wound torque–speed characteristics.

I a

R a

Supply
V

E M

FIGURE 20.61 The series-wound motor.

suggests that the speed–armature current characteristic will take the form of a hyperbola. Similarly,
Eq. (20.25) indicates that the torque–armature current characteristic will be approximately parabolic.
These general characteristics are illustrated in Fig. 20.62, along with the derived torque–speed charac-
teristic in Fig. 20.63. The general characteristics indicate that if the load falls to a particularly low value

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