AU-X095 - Sharp Air Conditioner Service Manual (repair manual). Page 22

22

There are two thermistors TH1 and TH2 in the temperature sensor circuit. They are connected in series with resistors
R10 and R9, and the divided voltage is applied to CPU IC1 analog input pins 2 and 4. CPU IC1 performs AD conversion
on the analog voltage from these two thermistors to perform the most appropriate cycle control.
C27, C28 and R11, R12, C30, C31 are inserted to absord noise.

There is a U-phase, V-phase, W-phase, and XYZ-phase power circuit built into the IPM as the power source for the
IGBT base current. It also contains six builtin OPIC elements to drive this base current, and is  to the control signal line.

When a Low PWM signal is output from CPU IC1 pins 34 to 39, the OPIC elements inside the IPM turn ON, the IGBT
base current flows, and the IGBT goes ON. When the CPU output is HIGH, the IGBT goes OFF.

Pairs 34 and 35, 36 and 37, 38 and 39 will never go ON (Low input) simultaneously. When the output changes, there is
an interval of more than 10 

µ

s during which both are OFF.

In this way, the six IGBT ON/OFF combinations are used to apply a 3-phase AC voltage to the compressor, causing the
compressor motor to turn.

R11

R12

+

C28

C30

C31

–

+

C27

R9

R7

5V

CN8

TH1

TH2

R10

–

CPU (IC1) pin 2

CPU (IC1) pin 4

DC 380V

CN2

PM1 (IPM)

R21~26

Compressor

CPU(IC1)