phytron
37
MA 2107-A005 EN
HALF STEP
The motor step resolution can be electronically multiplied by 2 by alternately energizing the
stepper motor’s phases 1, 1+2, 2 etc.. This is the HALF STEP mode. The torque,
however, is reduced in the half step mode, compared to the full step mode.
To compensate this lack of torque, the operating mode HALF STEP MODE WITH
TORQUE COMPENSATION was developed: the current is increased by
2
in the active
phase. Compared to the full step mode, the torque delivered is almost the same. Most of
the resonance is suppressed.
The following diagram shows extent and direction of the holding torques of a 4-step motor
during one revolution without and with torque compensation. In the full step position two
phases, in the half step position only one phase is energized. The total moment is the
result of superpositioning both phase moments.
The moment in the full step mode, M
FS,
as compared to the moment in the half-step mode,
M
HS
is:
M
FS
=
M
HS
×
2
This means, when a single phase is energized, the current must be increased by a
2
factor to obtain an identical torque.
Fig. 19: Holding torques without/with torque compensation