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6. Rotor magnetic pole position detection circuit
+12V
+5V
®
R101
SRI02
SRI03
®B)
att
a2
©)
ee rae
R104
rae me
ov
aes)
a
ae
os
ote
i
S)
Outdoor
microcomputer
Voltage at point ® about 260V-360V
Voltage at point
Voltage at point ©
Voltage at point ©
B: transis- "|. C'
'BY transis- | C' transis-'
"torON
:
[torON
Fig.
6 — 1
Rotor magnetic pole position detection circuit and voltage waveform at each part
e
Motor-induced voltage signal (voltage at point
© ) is phase-shifted by 90°
by passing lowpass filter
consisting of R101, R104 and C101 to make triangular wave (voltage at point
). In HIC, 3 phases of
this triangular wave are synthesized to produce composite wave (voltage at point © ). This composite
wave becomes a triangular wave with period of 1/3 times compared with original triangular wave.
e
Voltages at points
@ and © are compared by comparator to make voltage at point © .
Voltage at point © 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 falling waveform.
e
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.
— 132 -
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