Page 99 - Servo Motors and Industrial Control Theory -

92 5 Stepping Servo Motors

Fig. 5.1 Principal operation Stator
of a permanent magnet rotor
stepping motor B’ A

permanent
magnet
N

Y Y’

S
B

A’

Fig. 5.2 Stepping motor with stator
rotor energized externally
Electromagnet
A
B'

A' B

5.2 Stepping Motors with Small Step Angle

If the rotor and stator of stepping motors are made of laminated steels with many
teeth, a very small angle can be achieved. A step angle of 1.8 or 0.9° stepping mo-
tors are readily available in the market. The permanent magnet is buried in the rotor.
This is shown in Fig. 5.4.