Parallel
A winding that can be connected in parallel is either an 8-lead
motor or 6-lead motor.
8-lead
Connecting the two half-windings of an 8-lead motor in parallel
allows the current to divide itself between the two coils. It does
not change the effective number of turns and therefore the
inductance remains the same. At a given drive current, the torque
characteristics will be the same for the two half-windings in
parallel as it is for one of the windings on its own.
Connecting the windings of an 8-lead motor in parallel has the
same effect as halving the total resistance. For the same power
dissipation in the motor, the current may now be increased by
40%. Therefore, the 5 amp motor will accept 7 amps with the
winding in parallel. This provides a significant increase in the
available torque.
6-lead
“Parallel” in a 6-lead motor refers to the use of one half-winding
only. The current rating of a stepper motor is determined by
allowable temperature rise. Unless the motor manufacturer’s data
states otherwise, the rating is a “unipolar” value and assumes both
phases of the motor are energized simultaneously. Therefore, a
current of 5 amps means that the motor will accept 5 amps
flowing in each half-winding.
Summary
As a general rule, parallel connection is preferred over the other
options. It produces a flatter torque curve and greater shaft
power. Series connection is useful when a high torque is required
at low speeds. It allows the motor to produce full torque at low
speeds from lower current drives.
Care should be taken to avoid overheating the motor using series
connection since its current rating is lower in this mode. Series
connection also carries a greater likelihood of resonance problems
due to high torque produced in the low speed region.
C - 6
5345/5445 Installation and Hardware Manual
Rev F
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