5. Overload control ciricuit (OVL control circuit)
¥ Overload control is to decrease the speed of the compressor and reduce the load when the load on the air conditioner
increases to an overload state, in order to protect the compressor, electronic components and power breaker.
¥ Overloads are judgement by comparing the DC current level and set value.
¥ Fig. 5-1 shows the overload control system configuration and Fig. 5-2 is a characteristic diagram of overload judgement
values. There are two judgement methods-external judgement which mompares the externally set value with the DC
current value regardless of the rotation speed and internal judgement which compares the set value that according to the
rotation speed programmed in the micro computer software with the DC current value.
Detection
resistor
CT
0V
0V
To power module
negative terminal
DC current
DC current
Rotation speed data
DC voltage
Voltage amp.
circuit
(Internal judgement)
Judgement OVL
with respect to
externally set
value
Judgement OVL
according to the rotation
speed
Motor control
process
Selects data according
to the rotation speed and
DC voltage.
OVL start current data
A/D
convarter
A/D
convarter
AX-6N00 micro computer
Fig. 5-1 Overload Control System Configuration
Fig. 5-2
Judgement value according to the rotation speed
(internal judgement value)
External judgement value
Rotation speed
A/D
convarter
(R503)
RC filter circuit
Translation
Primary
- 300 -
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