User manual

PoStep60 user manual
9
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4.4.2 Stepper motor connections
The drive will work with 4-wire, 6-wire or 8-wire stepper motors.
Figure 3: Stepper motor wiring options
4.4.2.1 4-wire motors (type A)
are truly bipolar, and can only be run as such.
4.4.2.2 6-wire motors
can be wired two ways to work with the bipolar drive.
The first is half-winding (type B): In this method, one end wire, and the center-tap wire of the phase
is used. The other end is insulated and left unused. This method uses unipolar nameplate current
specifications, and will produce nameplate torque.
The second is series winding (type C): In this configuration, the center-tap is insulated, and unused.
This method uses all of the wiring per phase, but has double the number of wire turns as halfwinding
or unipolar mode. Because of this, the amperage requirement becomes half the nameplate rating.
Because the wire in the coil can handle more current than ‘half’, motor manufacturers will often
“boost” the torque rating by specifying currents up to 71% of unipolar rated current while running in
series mode. This is fine for FULL step motor drives, but not necessarily so good for microstepping
drives. Using this much can smear microstepping smoothness and accuracy. Any extra torque
achieved by this method will generally be lost to machine vibrations due to loss of microstepping
smoothness. The best performance will be somewhere between the 50% and 71% current rating.
CAUTION!
To avoid malfunctions please make sure the phase winds are connected correctly.
Resistance between leads of different phases is usually > 100kΩ. Resistance between
leads of the same phase is usually < 100Ω.
NOTE!
Simple method of finding correct pairs of each winding wires is as follows (before
proceeding none of the motor wires should be connected): take two random wires
and short circuit them. Try rotating the stepper axis. If the pair is matching the
resistance while trying to rotate the motor is much higher comparing to when none
of the wires is short circuited.
NOTE!
On the motor connector on the PoStep board there is a shield pin available (in the
middle). Please use proper shielding techniques for best performance.
type A
type B
type C
type D
type E