Hitachi RAS-50FH5 - Rotor Magnetic Pole Position Detection Circuit

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6. Rotor magnetic pole position detection circuit
A
B
C
D
E
18
19
20
retupmocorcimroodtuO
C605
+5V
0V
HIC
0V
+12V
WV U
C608
System power module
DC brushless
motor for compressor
R604
R605
R606
R607
106R
206R
306R
406R
306R
206R 806R
305C 205C
105C
116R
016R
90
6R
0V
C606
0V
C607
0V
36
33
34
35
47
Fig. 6-1 Rotor magnetic pole position detection circuit and voltage waveform at each point
E
D
C
A
No power
supplied
Upper arm
ON
No power
supplied
No power
supplied
Lower arm
ON
60 120 60 120
Induced voltage
Comparing process
60
Vd 150 ~330
Spike voltage
U phase
terminal voltage
Drive signal
Pole position
detection signal
(B) reference
voltage (1/2Vd)
Detection point
W
+
W
+
U
+
U
+
U
Ð
V
Ð
V
Ð
W
Ð
V
+
To detect U phase, voltage at point
C
is produced by driving motor induced voltage signal (voltage at point
A
) and
1/2 voltage of Vd (voltage at point
B
), and comparing with comparator.
For V phase and W phase, voltage at point
D
and voltage at point
E
are produced in the same way as above. Voltage
at point
C
is taken into indoor unit microcomputer, switching timing to U
+
transistor from W
+
transistor is produced by
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
D
and point
E
. Phases are shifted by 120 ° and 240 , respectively, comparing with U phase.