– 140 –
The Voltage amp. circuit amplifies the DC current level detected by the detection resistor after being converted to a voltage
and supplies it to the microcomputer. Receiving this, the microcomputer converts it to a digital signal and compares it with
the internal data to judge whether or not overload control is required.
The filter consisting of R245 and C217 removes high harmonic components from the voltage generated from the DC
current flowing to the detecition resistor, and supplies it to IC4 pin IC4 forms a non-inverting voltage amp. Circuit together
with the peripheral elements.
The microcomputer stores the set values which vary sccording to the rotation speed. When the DC current level exceeds
the set value, the microcomputer enters the overload control state.
The set Value is determined by the amplification of the voltage amp. circuit.
Amplification : high DC current : low
Amplification : low DC current : high
<During overload control>
Voltage amp. circuit
Fig. 7-7
Fig. 7-6
Voltage at micro computer pin
Rotation speed of compressor
Deceleration Acceleration
Deceleration Acceleration
Commanded rotation speed
Actual rotation speed
+
+
+
+
A
B
CT1
0V
0V 0V
0V
0V
0V
0V
0V
Is
Id
Vd
AX-8T11
MAIN P.W.B.
CN14
SPM2
CN13
IC1
0V
5V
5V
Is
D104 R005
R221
C218
R222
R245
R24
N1
P2
DC Current
Direct Current
Detection Resistor
DC320-360V
R248
C205
IC4
R006
C009
C105
C217
D205
R247
R249
R253
R500
C222
D204
C224
58
7
6
5
10
9
1
5
37
59
60
61
1
2
38
39