Bldc Motor Drive Circuit; Movement Description; Fan Motor Protection - Samsung RS20NCSL Service Manual

10-7. BLDC MOTOR drive circuit

● Movement description
When F-fan is driven to LOW RPM, Resetting the MICOM #40 pin with being set #39 always links
the R705 and R707 in a parallel. At this time, the voltage is devided between a parallel resistance
value and R706, impressed to OP-AMP. It makes Q1 turn ON, F-fan drive. If F-fan is in condition
of OFF, MICOM #39 pin is reset and F-fan is stopped. In case of the Comp.-fan, it is controlled by
the same method with F-fan. But its drive voltage is different with that because there is a
difference in E1 voltage /E2 voltage due to the difference of RPM.

※ Fan motor protection

When the fan is not run because of F-fan/C-fan freezing or power cord connection part inferiority,
fan self-signal is not occurred. So MICOM decides fan abnormality. At this time, perform the fan
three seconds ON, seven seconds OFF in five times. If there is no signal during the fan ON/OFF
five times, after 10 minutes pausing repeat the three seconds ON, seven seconds OFF in
five times.
If the signal is occurred during the three seconds ON, seven seconds OFF, MICOM decides that
operation is normal and releases all motor protect functions and performs a normal function.
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