Hitachi RAM-35QH5, Service Manual

Page: 49 / 78

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Drive
signal
Chopper
signal
Chopper
signal
DC
Current
level
AX-6M01
DC current
Detection
resistor
5V
DC330V
or 360V
Reset circuit
Overload external
judgement circuit
Current amplified
circuit
Drive
Circuit
IP signal
Reset Voltage
Peak current
cut off circuit
Outdoor micro computer
T
rip signal
synthesis circuit
Compressor
motor
Inverter
section
Fig. 7-2
●
The following gives details of operation for each circuit:
7-1 Peak current cut off circuit
Fig.7-3 shows peak current cut off circuit and waveforms at each point.
●
Ip cut circuit detects instantaneous surge current and stops inverter to protect components such as SPM.
●
As shown in diagram, when current exceeding 24A flows, voltage at point
A
detected by detection resistor
is input to pin
9
of INV-HIC, and voltage divided by R41 and R43 is input to pin
9
of IC1. Since this
voltage exceeds threshold of IC1, LO is output from pin
8
(voltage at point
B
). When LO is input to pin
9
of microcomouter, microcomputer stops drive output.
●
When drive output of microcomputer stops, all drive outputs are set to HI, and IC1 of HIC is initialized to
enter drive signal waiting status. Microcomputer again outputs drive signal 3 minutes later to re-start
operation.
DC current Id
Voltage at point
1.35V
27A
Voltage at point
A
B
A
—
Fig. 7-3
Detection
resistor
Negative
Terminal
DC
current
0V
R24
R41
0V
R43
0V
OC
R42
SPM
HIC
Control P.W.B.
IC1
CN14
IP cutter
Outdoor
microcomputer
F
C43
9 9
8
20 9 2 9
B