Hitachi RAS-50YH4 Service Manual page 70

6. Rotor magnetic pole position detection circuit
18
19
20
Pole position
detection signal
Fig. 6-1 Rotor magnetic pole position detection circuit and voltage waveform at each point
To detect U phase, voltage at point
1/2 voltage of Vd (voltage at point
For V phase and W phase, voltage at point
at point is taken into indoor unit microcomputer, switching timing to U
C
delaying 30° from rise waveform, ignoring spike voltage. In addition, switching timing to U-transistor from W-transistor is
produced by delaying 30° from fall waveform.
For V phase and W phase, in the same way as above, drive signals are produced from voltages at point
. Phases are shifted by 120° and 240°, respectively, comparing with U phase.
E
+5V
C
C605
D
0V
C606 E
0V
C607
0V
No power Upper arm
supplied
60
U phase
terminal voltage
A
(B) reference
voltage (1/2Vd)
Detection point
Spike voltage
C
D
E
W +
Drive signal
V —
is produced by driving motor induced voltage signal (voltage at point
C
), and comparing with comparator.
B
and voltage at point
D
System power module
B
+12V
C608
R604
R605
R606
R607
0V
HIC
No power Lower arm
ON supplied ON
120 60 120
Induced voltage
Comparing process
U + V +
W — U —
are produced in the same way as above. Voltage
E
– 80 –
DC brushless
motor for compressor
A
W V U
36 33 34 35 47
No power
supplied
60
Vd 150 ~ 330
W + U +
V —
+ transistor from W + transistor is produced by
0V
) and
A
and point
D