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Amplification : iow
OC voltage : low
OC current: high
Amplification : 8.5 times
DC voltage : 260V
Amplification : high
OC voltage : high
DC current : low
DC current
G %
Rotation speed
Fig. 8-8
<During start current control>
@ Itis required to maintain the start current (DC current) constant to smooth the start of the DC motor for the
compressor.
@
The RAC-32CNH1
uses software to control the start current.
@ The start current varies when the supply voltage varies. This control method copes with variations in the
voltages as follows.
(1) Turns on the power module's U* and V transistors so the current flows to the motor windings as shown in
Fig8-9.
(2) Varies the turn-ON time of the W* transistor according to the DC voltage level and the start is controlled so
the start current is approx. 15A as shown in Fig. 8-10.
Power module
OC current
Compressor motor
DC 260-360V
Detection
tesistor
Fig. 8-9
Chopper duty: high
OC voltage: low
DC voltage: 280V
DC vottage: high
W transistor
ON-time
OC voltage (start current)
Set value
OC current
(A)
jet
Aad
Fig. 8-10
— 148 —
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