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Pancake Resolvers >> Brush Type Motors >>
Brushless DC Motors
1
S1 0
1
S2 0
on
Q1 off
+VS
-VS
CW Rotor Position - Electrical Degrees
0 60 120 180 240 300 360
(S1 ● S2)
on
Q2 off
(S1 ● S2)
on
Q3 off
(B)
on
Q4 off
(S1 ● (S1
S2)
● S2)
+
0B 3-4 0
-
+
0A 1-2 0
-
Q4
Q2
0A
2
with reference marks to which the position
sensors can be aligned.
1
Q1
3 4
0B
+VS -VS
Figure-7. Sensor output, commutation logic, and
and winding excitation waveform for a
two phase brushless DC motor.
The commutation points and output torque
for a three phase brushless motor was shown
in Figure 3.The commutation angle is 60
electrical degrees, and the winding are
switched “on” at 30 electrical degrees before
the peak torque position, and switched “off
” at 30 electrical degrees after the peak
torque position.The current polarity for
Q3
(A)
(C)
(D)
(800) 777-3393
Figure-8. Sensor output, commutation logic and
winding excitation waveform for a three phase
brushless DC motor.
each phase during each commutation segment
is shown in Figure 3B.The commutated
output torque versus motor
position(in electrical degrees) is shown in
Figure 3C.
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Commutating Brushless DC Motors