Hitachi RAS-E10H2 Service Manual page 53

〜
approx.
DC 235 V
Current
transformer
Detailed description for the operation of each circuit is given here.
6-1. Peak current cutoff circuit
Fig. 6-3 shows the peak current cutoff circuit and waveforms at each section.
DC current Id
25A
Voltage at point
A
◯ ◯ ◯
0.6V
Voltage at point
B
◯ ◯ ◯
Ip cut circuit detects instantaneous large current and operates to protect various parts, such as IPM,
by stopping inverter.
When current exceeding 25A flows as shown in the diagram, voltage at point
detection resistor, is divided by R906 and R905, and then input to IPM pin
threshold value, IMP pin
microcomputer, microcomputer will stop drive output, and self-diagnosis lamp will enter a 2-time
blinking mode. When peak current is detected, IPM holds lower arm output off status for a fixed
period (approx. 4 msec.), and then enters drive signal standby mode. Microcomputer outputs drive
signal 3 minutes later to restart operation.
5V, 12V
Reset voltage
Reset circuit
DC voltage
Dividing resistor
Input current
DC current
Current amplifier
circuit
I P M
DC current
is set to Lo (voltage at point
24
◯ ◯ ◯
Chopper
signal
Drive circuit
Peak current
Ip signal
cutoff circuit
Detection
resistor
Fig. 6-2
Ａ
Detection resistor
N
Ｒ ０ ０ １
Ｒ ９ ０ ６
０ Ｖ
０ Ｖ
２ ２ ２ ２ ６ ６ ６ ６
F０
２ ２ ２ ２ ４ ４ ４ ４
Fig. 6-3
) . When Lo signal is input to pin
◯ ◯ ◯ B
- 57 -
◯ ◯ ◯
＋
Drive signal
◯ ◯ ◯
−
DC current DC current
０ Ｖ
(Main P.W.B.)
HIC
５ Ｖ
1 1 1 1 ２ ２ ２
Ｂ
０ Ｖ
, detected by
◯ ◯ ◯ A
. . Since this exceeds
◯ ◯ ◯ ◯ ◯ 26
Compressor
motor
Outdoor
microcomputer
1 1 ５ ５
Ｉ
Ｐ
of
15
◯ ◯ ◯