Hitachi RAM-40QH5 Service Manual page 49

5V
Reset circuit
Overload external
judgement circuit
DC330V
or 360V
Current amplified
circuit
The following gives details of operation for each circuit:
G
7-1 Peak current cut off circuit
Fig.7-3 shows peak current cut off circuit and waveforms at each point.
DC current Id
27A
Voltage at point A
1.35V
Voltage at point
B
Ip cut circuit detects instantaneous surge current and stops inverter to protect components such as SPM.
G
As shown in diagram, when current exceeding 24A flows, voltage at point
G
is input to pin
9
voltage exceeds threshold of IC1, LO is output from pin
of microcomouter, microcomputer stops drive output.
9
When drive output of microcomputer stops, all drive outputs are set to HI, and IC1 of HIC is initialized to
G
enter drive signal waiting status. Microcomputer again outputs drive signal 3 minutes later to re-start
operation.
Reset Voltage
Chopper
signal
DC
Current
level
AX-6M01
Negative —
Terminal
DC
current
A
Detection
R24
resistor
0V
of INV-HIC, and voltage divided by R41 and R43 is input to pin
Chopper
signal
Drive
Circuit
IP signal
Peak current
cut off circuit
Detection
resistor
Fig. 7-2
SPM
HIC
IC1
R41
9 9
0V 0V
Fig. 7-3
(voltage at point
8
– 55 –
Drive
signal
Inverter
section
DC current
Control P.W.B.
B
CN14
20 9 2
R42
8
F
OC
detected by detection resistor
A
of IC1. Since this
9
). When LO is input to pin
B
Compressor
motor
9
IP cutter
Outdoor
microcomputer