– 44 –
Intelligent power module switches power supply current according to position of the compressor motor
rotor.
The switching order is as shown in Fig. 4-2.
At point
E
: U+ is ON, V- is ON (circuit in Fig. 4-1)
At point
F
: U+ is chopped (OFF), V- is ON (circuit in Fig. 4-4)
Fig. 4-2 Switching order of power module
Upper arm transistor is controlled to ON/OFF by 4.8kHz chopper signal. Rotation speed of the compressor
is proportional to duty ratio (ON time/ ON time + OFF time) of this chopper signal.
Time T in Fig. 4-2 shows the switching period, and relation with rotation speed (N) of the compressor is
shown by formula below;
N = 60/2 X 1/T
Fig. 4-3 shows voltage waveform at each point shown in Figs. 4-1 and 4-4. First half of upper arm is
chopper, second half is ON, and first half of lower arm is chopper, second half is ON.
Fig. 4-3 Voltage waveform at each point
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
→
DC current detection
resistor
→
Point
B
(Fig. 4-1)
(2) When U+ transistor is OFF: (by inductance of motor coil) U coil
→
V coil
→
V- transistor
→
U- diode
→
Point
A
(Fig. 4-4)
V
Time
W
T
V
U
V
Upper arm
transistor
Lower arm
transistor
W
U
E
F
+
+
+
+
-
-
-
U
transistor chopped
Chopping period
T
transistor ON
U
280V-300V
Voltage at
Upper arm transistor
Current at
ON
+
-
Chopping period (208µ sec.)
Summary of Contents for Summit RAC-35YH6
Page 17: ... 15 CONSTRUCTION AND DIMENSIONAL DIAGRAM MODEL RAS 35FH6 INDOOR UNIT ...
Page 22: ...RAS 35FH6 CIRCUIT DIAGRAM 20 08A392_05_RAS_35FH6_20 21_A2_E 2008 2 22 18 40 20 ...
Page 25: ... 23 button 25 26 26 27 28 26 RAS 35FH6 08A392_07_RAS_35FH6_23_A3_E 2008 3 7 10 07 23 ...
Page 92: ... 90 PARTS LIST AND DIAGRAM INDOOR UNIT MODEL RAS 35FH6 ...
