Hitachi RAS-E10H2 - Reversing Valve Control Circuit Details

Intelligent
po
wer
module
sw
itches
po
wer
supply
current
according
to
position
of
the
compressor
motor
rotor
.
The
sw
itching order is as sho
wn in Fig.
3-2.
At point E :
U
+
is ON,
V
–
is ON (circuit in Fig.
–
is ON (circuit in Fig.
–
3-1)
is ON (circuit in Fig. 3-1) is ON (circuit in Fig.
At point F :
U
+
is chopped (OFF),
V
–
is ON (circuit in Fig.
–
is ON (circuit in Fig.
–
3-4)
is ON (circuit in Fig. 3-4) is ON (circuit in Fig.
N = 60/2 X 1/T
Fig.
3-3
sh
ow
s
v
oltage
wave
fo
rm
at
each
point
sho
wn
in
Figs
.
3-1
and
3-4.
F
irst
half
of
upper
ar
m
is
chopper
, second half is ON, and first half of lo
wer ar
m is chopper
, second half is ON.
U
–
diode
–
diode
–
→
Point A (Fig. 3-4)
When power is supplied U
+
→
V
–
, because of that U
+
is chopped, current flows as shown below;
(1) When U
+
transistor is ON: U
+
transistor
→
U coil
→
V coil
→
V
–
transistor
–
transistor
–
→
DC current
detection resistor
→
Point B (Fig. 3-3)
(2) When U
+
transistor is OFF: (by inductance of motor coil) U coil
→
V coil
→
V
–
transistor
–
transistor
–
→
V
T
ime
W
T
V
U
V
Upper arm
transistor
Lower arm
transistor
W
W
U
E F
E F
+ +
W
+ +
W
+
+
- -
V
- -
V
-
Fig. 3-2 Switching order of power module
Fig. 3-3 Voltage waveform at each point
U
transistor chopped
Chopping period (208µ sec.)
Chopping period
T
transistor ON
◯
◯
B
◯
◯
◯
A
◯
U
280V
-300V
V
oltage at
Voltage atV
Upper arm transistor
Upper arm transistor
Upper arm transistor
Upper arm transistor
Current at
ON
+
-
Upper Upper arm transistor is controlled to ON/OFF
by
2.5kHz - 5kHz chopper signal. Rotation speed of
the compressoris proportional to duty ratio (ON time/ ON time + OFF time) of this chopper signal.Time
T in Fig. 3-2 shows the
sw
itching period, and relation with rotation speed (N) of the compressor
issh
ow
n
by
fo
rm
ula below;
Table 3-1
Ip (peak current cut)
LD301
Blinks 2
times
Blinks 3
times
Blinks 4
times
LD301
LD301
Self-diagnosis
Self-diagnosis lamp
and mode
Abnormal low speed
rotation
Switching incomplete
- 50
-