Sharp AE-X26FR-N Service Manual page 16

AYXP26FRN
2. Explanation of cluster circuit
The cluster unit generates cluster ions, which are circulated throughout the room by the air flow created by the blower fan (indoor unit fan motor) in
the air conditioner unit.
1) When microcomputer output 1 turns "H," the IC6-1 output changes to "Lo," turning ON the SSR and applying 230 V to the cluster unit for the gen-
eration of cluster ions (positive and negative ions).
2) When the SSR is ON, monitor voltage (1 to 3.5 V) is applied to the microcomputer input.
The monitor voltage is lower than 0.1 V or higher than 4.5 V for 30 consecutive minutes, an error is detected and the cluster drive output (SSR)
remains OFF until the operation is shut down.
Note that the above condition will not cause the air conditioner to shut down in an error mode, and the air conditioning operation continues.
3) For a cluster mode change, microcomputer output 2 changes to "H," and this sets the IC6-2 output to "Lo" and turns ON the Q8 (digital transistor).
As a result, the relay inside the cluster unit is applied with 12 V, and the internal relay turns ON.
When the SSR is turned ON in this condition, more negative ions are generated to provide negative-ion-rich air.
• Cluster mode switching is usually performed in the cluster OFF (SSR = OFF) status.
AC230V
Microcomputer output 1
3. Outline of PAM circuit
3.1. PAM (Pulse Amplitude Modulation)
The PAM circuit varies the compressor drive voltage and controls the rotation speed of the compressor.
The IGBT shown in the block diagram charges the energy (electromotive force) generated by the reactor to the electrolytic capacitor for the inverter
by turning ON and OFF.
Noise
AC
filter
230V
When the IGBT is ON, an electric current flows to the IGBT via the reactor (L5) and diode bridge (DB2).
When the IGBT turns OFF, the energy stored while the IGBT was ON is charged to the voltage doubler capacitor via the diode bridge (DB1).
R75
R23
IC6-1
R20
Reactor L5
Reactor L6
AC clock
detection
circuit
[PAM drive circuit]
Microcomputer (IC1)
PAM drive circuit block diagram
12V
R76
C23
SSR
RE RN NF2 C28
DB1
+
DB2
IGBT
drive
circuit
IGBT
2 – 12
Cluster unit
8 1
5 3
3 5
2 6
1 7
IPM
Compressor
Overvoltage
Compressor
detection
position
circuit
detector