Samsung RM255BABB Training Manual page 81

CIRCUIT DESCRIPTIONS
12-9. INTERNAL REFRIGERATOR FAN MOTOR OPERATING CIRCUIT
MOTOR DRIVE CIRCUIT DESCRIPTIONS
1) This refrigerator uses BLDC MOTORS for the purpose of saving power consumption, the BLDC MOTOR is is used for
the freezing compartment, cooling compartment, and machine room motor (this motor drive circuit is a common circuit
used in other models)
2) PRINCIPLE OF OPERATION
In the above electric circuits, you may notice that the circuits are similar for each motor. For example, the F-FAN motor
is represented here. FAN motor operates in high/low speed according to conditions. To operate the F-FAN, a certain
voltage should be applied OP-AMP #13 PIN as shown in the Figure.
A certain voltage is applied OP-AMP #13 according to the operation of MICOM #37(HIGH RPM), #36(LOW
PRM). Tripled by this voltage (Gain value currently set), you may get the voltage applied the motor.
If OP-AMP #13 PIN voltage is 3V, 9V is impressed into motor by 3V x 3 = 9V formula.
3) COMPARISON IN HIGH/LOW SPEED
HIGH
LOW
* Voltage errors range within
VOLTAGE APPLIED TO MOTOR
F-FAN R-FAN C-FAN
11.1V 9.7V 9.4V
9.7V 9.7V 8.0V
0.2V.
80 80
Impressed voltage on this part X3= motor operating voltage
REMARKS
In case of normal motor operation, a certain
frequency is input to MICOM #31(F), #30(R),
#29(C), and the MICOM checks out for any
errors in motor operation based on this signal.
(Frequency (Hz) x 12 = Motor rpm)