– 74 –
6. Rotor Magnetic Pole Position Detection Circuit
(_
£
£
£ £
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
000
0
0
0
0
00
0
0
0
0
0
0
0
00
0
0
000
0
0
0
0
0
0
0
0
0
0
0
00
0
0
+
-
+
-
+
-
A
B
C
D
)
(_
HIC
R101
R102 R103
C104
C105
C106
C103
C102
C101
R106R105
R104
63
61
60
62
59
58
57
Outdoor
microcomputer
_
5V
0V
+ 12V
+
zzz
+
zzz
+
zzz
+
zzz
+
zzz
+
zzz
4
3
Voltage at point
C
Voltage at point
D
0.6V
Voltage at point
B
B
-
transis-
tor ON
C
-
transis-
tor ON
B
+
transis-
tor ON
C
+
transis-
tor ON
Voltage at point
A
about 230V
Fig. 6
-
1 Rotor magnetic pole position detection circuit and voltage waveform at each part
● Motor-induced voltage signal (voltage at point A ) is phase-shifted by 90° by passing lowpass filter
consisting of R101, R104 and C101 to make triangular wave (voltage at point B ). In HIC, 3 phases of
this triangular wave are synthesized to produce composite wave (voltage at point C ). This composite
wave becomes a triangular wave with period of 1/3 times compared with original triangular wave.
● Voltages at points B and C are compared by comparator to make voltage at point D.
Voltage at point D is taken into microcomputer and timing of switching from V
–
transistor to W
–
transistor
is made by rising waveform, and timing of switching from V
+
transistor to W
+
transistor is made by failling
waveform.
● For other 2 phases (V phase and W phase), the operation is the same and phases are shifted by 120°
and 240° respectively compared with U phase waveform.
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