Sharp AE-Z35PR, Service Manual

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2-12
AY-ZP35PR
2. Explanation of cluster circuit
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fan) in the air/air heat pump unit.
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).
1
3
12V
R39
Q11
Microcomputer output
1
3
Cluster unit
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.
PAM drive circuit block diagram
Reactor L5
[PAM drive circuit]
+
Microcomputer (IC1)
AC
230V
Compressor
Noise
filter
AC clock
detection
circuit
DB1
IPM
DB2
Compressor
position
detector
IGBT
drive
circuit
IGBT
Overvoltage
detection
circuit
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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).As such, by varying the ON/OFF duty of the IGBT, the output voltage is varied.
Stored energy
Reactor
L5
DB1
DB2
IGBT
IGBT ON
IGBT OFF
L6
3.2. High power factor control circuit
This circuit brings the operating current waveform closer to the waveform of commercial power supply voltage to maintain a high power
factor.
Because of the capacitor input, when the PAM circuit is OFF, the phase of the current waveform deviates from the voltage waveform as
shown below.
To prevent this deviation, a current is supplied during the periods indicated by "O" in the diagram.
To determine the length of period to supply a current, the zero-cross timing of the AC input voltage is input to the microcomputer via the
clock circuit.