ABCDA
Figure 5.34: Energizing Two Phases Simultaneously
Figure 5.35: Timing Diagram, Half-Stepping Motor
Both phases will pull equally on the motor will move the rotor only
half of the full step. If the phases are always energized two at a time,
the motor still makes full steps. But, if the user alternates one and two
phases being activated simultaneously, the result is that the motor will
move only half a step at a time. This method of driving a stepper
motor is called half-stepping. The advantage is that we can get double
the resolution from the same motor with very little effect on the
driver's side. The timing diagram for half-stepping is shown in
(
Figure 5.35).
A
12345678
B
C
D
Now, what happens if we energize the same two phases
simultaneously but with different currents? For example, lets say that
phase A has the full current and phase B only half. This means that
phase A will pull the rotor tooth twice as strongly as B does. The rotor
tooth will stop closer to A, somewhere between the full step and the
half step positions (
Figure 5.36).
Figure 5.36: Energizing Two Phases with Different Intensities
ABCDA
5-28 Section 5 – Motion Control Tutorial
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