'!<eys to the 5-PHASE cont.)
2-PHASE VIBRATION
5-PHASE VIBRATION
Che figures to the right visually em
phasizes the smoothness difference
between a standard step motor and
the Five-Phase motor. Both motors
are running at 60 rpm. The oscillo
scope photos are made by a11aching
a DC tacho-generator to the.shaft of
'he step moto'r and the� looking at
the output voltage from· the tacho
generator. If the step motor
move
ment were perfectly smooth, the OS·
cilloscope picture would show a flat
line. The ·closer to a flat line, the
smoother the movement.
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.
The next figure graphically shows the
difference between a standard step
motor and a Five-Phase motor. The
graph is made by measuring the max
imum peak-to-peak value from the
tacho·generator at each speed.
(Measuring the difference between
the peaks and valleys
in
the previous
figure at each speed). You can see
Five-Phase clearly makes a differ
ance.
The torque ripple in a Five-Phase
versus a standard step motor is shown
in figures to the right. The difference in
lowest to the highest torque value of a
standard step motor is 29%. The same
value for a Five-Phase is only 5%. This
six-fold dilference is one of the reasons
for the Five-Phase's super-smooth
moves.
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2-PHASE TORQUE RIPPLE
S·PHASE TORQUE RIPPLE
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Torque Ripple 29%
Torque Ripple 5%
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BASIC CHARACTERISTICS
E: excellen1 F fair
These graphs a,e ror comp313ltve vse onty
G: good
P poor
A: average
For ac1ua1 oet1ormance ditla orease see page 14
'
VIBRATION
SPEED
RESOLUTION
STEP
ACCURACY
S·Phase
G
2·Phase
F
Micro Step
G
(2·Phase)
(Low speed)
The basic characteristics comparison chart
above Is a summary or the strengths and
weaknesses of standard step motors, Five·
Phase Pentagon-Drive and a 2-phase step
motor driven with a micro-step driver. The
Five-Phase and Micro Stepper both have
good low vibration characteristics. The
Microstepper ls better than the five phase
at very tow speeds (less that Y.. rps) but the
Five-Phase is better at higher speeds
G
A
p
G
E
A
E
E
F· P
speeds (over about 1 rps) Speed charac·
leristics of a m1crostepper are poor, and
their top speeds are 1000 10 1 800 rpm,
while the Five·Phase can go to 6,000 rpm
At 1800 rpm, a 25.000 slep/revoluhon
m1crostepper would be moving al 750.000
steps per second! This would need a very
expensive controller indeed 10 run at 1h1s
speed Microsteppers have more resolu·
1,on (number of stopping positions per
RESPONSE
TORQUE
AUDIBLE
NOISE
G
E
A
F
E
p
G
G
A
revo1u11on) than a five phase. but the
accuracy of those positions 1s fair to poor,
and becomes even worse under all but the
lightest loads. M,crosteppers have poor
torque because neither phase in the motor
1s ever turned completely on at the same
time. Current 1s related to torque, so their
output toroue ,s less for a given motor
lrame s12-e
6
