IVT 12PHR-N Service Manual page 19

2. Explanation of Plasmacluster 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) in the air to air heat pump unit.
1)When microcomputer output turns "H", the Q11 output changes to "Lo", turning ON the cluster unit for the generation of cluster ions
(positive and negative ions).
AC230V
Microcomputer output
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.
AC
230V
When the IGBT is ON, an electric current flows to the IGBT via the reactor (L1) and diode bridge (DB2).
When the IGBT turns OFF, the energy stored while the IGBT was ON is charged to the voltage capacitor via the diode bridge (DB1).
As such, by varying the ON/OFF duty of the IGBT, the output voltage is varied.
12PHR-N_S530612PHRN.indd 13
R17
R19
IC13
R18
Reactor L5
Noise
filter
AC clock
detection
circuit
[PAM drive circuit]
PAM drive circuit block diagram
Reactor
Stored energy
L5
IGBT ON
IGBT OFF
12V
SSR1
R16
C5
DB1
+
DB2
IGBT Overvoltage
drive
circuit
IGBT
Microcomputer (IC1)
DB1
DB2
IGBT
2-13
Cluster unit
5 4
1 1
6 4
2 1
IPM
Compressor
Compressor
detection
position
circuit
detector
12PHR-N
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