Toshiba 4580, Service Manual

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6570/5570 SCANNER 7 - 6 Mar. 1999 © TOSHIBA TEC
7.4 Drive of the 5-Phase Stepping Motor
7.4.1 Features
Up till now, 2-phase hybrid stepping motors having a step angle of 1.8 have been regarded as being the
highest performing motors. Compared to these motors, however, 5-phase stepping motors have the
following features:
(1) A small step angle (full step: 0.72°, half-step: 0.36°) achieves a resolution 2.5 times that of conven-
tional stepping motors. As 2.5 times the number of steps can be used when moving the same dis-
tance, high-speed positioning using optimum acceleration and deceleration is now possible.
(2) Extremely small fluctuation in operating torque achieves little vibration and smooth rotation. This
makes a 5-phase stepping motor ideal for applications where uneven torque and noise are a prob-
lem.
(3) As vibrations are small even at the resonant point, special dampers are not required, and the motor
can be used in all operating ranges.
(4) The self-start frequency is roughly 2.5 times higher than that of 2-phase stepping motors, and moreo-
ver, 5-phase stepping motors do not have a resonant range. This achieves speed control with a large
variable speed ratio without the need for acceleration and deceleration.
(5) Response is much faster than that of 2-phase stepping motors, allowing higher speed setting.
(6) 4- and 5-phase excitation systems achieve excellent damping characteristics.
(7) The step angle can be varied (e.g. 0.72°, 0.36°, 0.18°) depending on the excitation system.
7.4.2 Principle of the stepping motor
The fundamental differences between a 2-phase hybrid stepping motor and a 5-phase stepping motor
are the number of stator main poles and the winding configuration. A 2-phase stepping motor is wound in
a 2-phase, 4-pole configuration, whereas a 5-phase stepping motor is wound in a 5-phase, 2-pole con-
figuration. Fig. 7.4-1 shows the relationship between stator and rotor teeth in a 5-phase stepping motor,
and the winding configuration.
Fig. 7.4-1 Structure of 5-phase Stepping Motor
A phase (blue)
Rotor
B phase (white)
C phase (brown)
(green)
(gray)
(purple)
(yellow)
(red)
E phase (orange)
D phase (black)
Stator