Hitachi RAS-50WX8 Service Manual page 94

7. HIC and Peripheral Circuits
Fig. 7-1 shows the microcomputer and its peripheral circuits, Table 7-1, the basic operation of each circuit block,
and Fig. 7-2, the system configuration.
Detection Resistor
A
B
Table 7-1
Circuit block
Detects DC current flowing power module and during overcurrent (instantaneous value) flows,
Peak current
stops upper/lower arm drive circuits and also produces IP signal by which drive signal output is
cutoff circuit
stopped.
Compares voltage detected, amplified and input to HIC with set voltage value in microcomputer,
Set value circuit
and controls overload when set value exceeds input voltage.
Voltage amplifier Voltage-amplifies DC current level detected by the detection resistor and inputs this to
microcomputer, Internal or external overload is judged in microcomputer.
circuit
Reset circuit Produces reset voltage.
Modulates chopper signal to drive signal and stops according to presence/absence of IP signal or
Trip signal
reset signal.
synthesis circuit
R24
DC Current
N1
R41
9
0V 0V
Is
CT1
D104 R005
58
+
0V
0V
0V 0V
12V
62
+
0V
Fig. 7-1 Microcomputer (AX-8T11) and Peripheral Circuits
SPM2-HIC
IC1
OC
9
F
8
P2
21 20
10 9
CN14 CN13
1 2
C205
0V
38 39
6
7
R245
+
IC4 R248
+
5
5V
R222
R221
0V
12V
0V
2
1
+
JW10
3
IC5
R288 R252
0V 0V 0V 0V
Basic operation
– 134 –
Direct Current
DC320-360V
SPM2
1
MAIN P.W.B.
5
37
IC1
59 Vd
AX-8T11
0V
17
Ip
5V
Id
60
0V
61
Is
0V
48 RESET
0V