Hitachi RAM-60QH4 Manuel De Service page 90

6. Rotor magnetic pole position detection circuit
R601
18
C605
0V
19
C606
0V
20
C607
0V
When the DC brushless motor is rotated, it also operates as power generator, generating reverse electromotive force
according to number of rotations. This reverse electromotive force is voltage-divided by R503 - R505 and R608 -
R610, and appears as point A voltage. IC3 compares and digitalizes point
DC voltage (Vd) is voltage-divided by R501, R502 and R611), and inputs this to microcomputer as position detection
signals for points C , D
signals, in order to control the rotation of the brushless motor.
＋ ＋ ＋
−
− −
+5V
+12V
R603
R602
3
C
＋
1
−
D
＋
2
−
E
＋
13
−
＋
14
−
12
IC3
0V
Fig. 6-1 Rotor magnetic pole position detection circuit
and E . Microcomputer switches inverter using optimum timing based on position detection
Inverter
R502
R501
R604 B
R605
7
6
R606
5
R607
4
11
10
R611
9
8
– 102 –
W V U
R505
R504 R503
A
R608
R609 R610
0V
voltage with point voltage (in which
A B
DC brushless motor
for compressor