Hitachi RAS-E10H2 - Page 56

DC voltage : Low
DC current
 : High
DC voltage
 : High
DC current
 : Low
DC voltage
 : 260V
Rotation speed
DC current
0
0
IPM
DC current
P
DC
Voltage
N
Detection
resistor
U
+
V
+
W
+
U
−
V
−
W
−
U
V
W
Compressor motor
Fig. 6-8
Fig. 6-9
(3) Start current control
R003,R004,R608,R613,
detect
the
DC
voltage
at
the
power
circuit.
The
microcomputer
receives
a
DC
voltage
and
applies
correction
to
the
overload
set
value
so
the
DC
current
will
be
low
when
the
DC voltage is high.
(Since the load level is indicated by the DC voltage multiplied by DC current, R247, R248, R249 are
provided to perform the same overload judgement even when the voltage varies.)
It
is
required
to
maintain
the
start
current
(DC
current)
constant
to
smooth
the
start
of
the
DC
motor
of the compressor.
RAC-E10H2 uses software to control the start current.
The
start
current
varies
when
supply
voltage
varies.
This
control
method
copes
with
variations
in
the voltages as follows.
(1)
Turns
on
the
power
module’s
U
+
and
V
-
transistors
so
the
current
flows
to
the
motor
windings
as shown in Fig. 6-9.
(2)
Varies
the
turn-ON
time
of
the
U
+
transistor
according
to
the
DC
voltage
level
and
the
start
is
controlled so the start current is approx. 10A .
Fig. 6-10
Fig. 6-11
HIC
Microcomputer
RESET OUT.
RESET
19
7
C204
0V
R252
1
0V
8
2
3
IC5(1/2)
+
5V
D208
R287
C215
R284
R286
C225
R285
C226
R292
R289
R288
0V 0V 0V 0V
12V
12V line
12V line
5V line
5V line
Reset volage
Reset volage
Time
Time
10.9V
9.9V
12
6
0
12
6
0
Power is ON Voltage (V)
Power is OFF Voltage (V)
- 60
-