Hitachi RAS-50YH4 Service Manual page 80

11. Outdoor DC Fan Motor control circuit.
Main P.W.B
FM-15V
5V
4 1
PQ102
3 2
0V
This model uses DC Fan Motor which has a controller circuit in the Motor.
●
This DC Fan Motor will rotate by control voltage apply to Vsp input. (Voltage range: 1.7 to 7V DC)
●
Vsp high : Faster ; Vsp low : slower ; Vsp lower than 1.7V : stop
Motor will output FG pulse by following this motor revolution.
●
Outdoor Microprocessor will output PWM control signal from FMCHOP terminal by following the instruction
●
from indoor Microprocessor.
This PWM control signal will convert to Vsp voltage by smoothing circuit (Q101 & RC filter)
●
Fan motor will start to rotate when Vsp was proceeding over than 1.7V, and generate FG pulse by rotation
●
speed.
FG pulse will feed back to Outdoor Microprocessor through PQ102.
●
PQ102 is the isolator between Microprocessor circuit and DC Fan Motor circuit, which has to match the Fan
●
Motor revolution with instructed revolution. Such as...
FG feedback: Faster – Instruction: Slower ... Decrease pulse width
FG feedback: Slower – Instruction: Faster ... Increase pulse width
FG pulse is also used for Fan Motor failure detection
●
Microprocessor will monitor FG pulse 30 seconds after start the fan motor. If there is no signal detected, it
●
will consider that the Fan Motor was malfunction and stop the operation. In this case, LD302 on control PWB
will blink 12 times. (Fan Motor lock detected)
R107 and IC4 are used for Fan Motor over current
●
System power module
+
3 2 1
CN12
1 2 3
2A-FUSE
C101
FM-15V
R107
Q101
D101
+
R101
R102
FM-0V
Ap 7V
5V
t
33.3KHz
5V
T/2
T
U
V
+ +
W
1 2 3 4 5
RC Filter
1
2
3
0V
4
Vcc
5
PWM control voltage
6
FG Pulse
7
CN6
HIC
R108
FM-0V 0V
0V
R283
61
60
59
R242
Fig. 11-1
– 90 –
Power supply for DC fan motor from smoothing
capacitor in system power module
VSD
BOARD
DC Fan motor with control board
12V
C208
0V
8
IC4
R244
2
–
1
+
3
+
R246
0V 0V
R297
Q201
R298
0V
Motor coil
Microcomputer
65
75
FM–60˚ el
15
FG Pulse
input