Haier KFR-25GW air conditioner control circuit schematic diagram

The control circuit of Haier KFR-25GW air conditioner uses CM93C-OQ57 emblem processor as the main control chip, as shown in the figure.
    1.
    The AC 220 V mains power supply of the microprocessor is stepped down by transformer T01, rectified by D01 and filtered by C2 to obtain a DC voltage of approximately +12 V. The voltage is divided into
two outputs, one is used to power the relay, and the other is stabilized by the 7805 three-terminal voltage regulator and outputs a stable voltage of +5 V to power the Emblem processor.
    2. Basic circuit of CPU
    (1) +5 V power supply circuit. The +5 V DC stable voltage output by the 7805 three-terminal voltage regulator is sent to the @ pin of the microprocessor (@ pin is grounded
), so that the microprocessor has normal power supply.
    (2)Reset circuit. The reset voltage of the microprocessor is input from the @ pin, and the reset voltage is generated by the T600D circuit. When the +5 V voltage is less
than 4.5 V, T600D outputs low level; when the +5 V voltage is higher than 4.5 V, T600D outputs high level. Since there is a process to establish the +5 V voltage
, the power supply to the reset terminal lags behind the +5 V voltage, allowing the microprocessor to complete the reset action.
    (3) Clock oscillation circuit. The internal oscillation circuit of the microprocessor and the quartz crystal connected to the @ pin and @ pin form a clock signal generator.
Its oscillation frequency is 6.0 MHz, which provides an accurate clock signal for the microprocessor.
    3. Microprocessor signal input circuit
    The microprocessor has the following 7 input signals:
    (1) Remote control signal. The control signal received by the remote control receiving circuit is amplified, filtered and shaped before being sent to the @ pin of the microprocessor.
    (2) Emergency operation control input signal. One end of the emergency button sw is connected to ground, and the other end is connected to the @ pin of the microprocessor through R45. When
the button is pressed, the @ pin inputs a low level, and the air conditioner performs the emergency operation function (usually when detecting the air conditioning pipe).
    (3) Room temperature sensor input signal. The room temperature sensor ROOM TH - terminal is connected to +5 V voltage, and the other terminal is connected to R31 and R33.
The room temperature signal divided by these two resistors is input by the @ pin of the microprocessor. A capacitor C16 is connected in parallel to both ends of the sensor ROOMTH. At
normal temperature, the voltage at the input terminal of the temperature sensor is about 2V.
    (4) Indoor pipe temperature sensor input signal. The output signal of the indoor temperature transmitter PIPE TH is divided by the resistors R30 and R32 and then
input by the @ pin of the microprocessor. This voltage signal reflects the temperature of the indoor unit coil. Under normal circumstances, the input
voltage of the indoor temperature sensor is about 3V.
    (5) Exchange zero-crossing detection signal. In order to prevent the thyristor from being damaged, it must be turned on near the zero point of the alternating current during control, and the microprocessor
must input a signal that reflects the zero point of the alternating current. This signal is generated by DQ1, etc., and is input from the @ pin of the microprocessor.
    (6) Compressor filter signal. In order to prevent the air conditioner from being damaged due to AC overcurrent , the signal input circuit is equipped with an overcurrent protection circuit,
which is composed of transformer CT1, etc. The detected compressor overcurrent signal is input by the @ pin of the microprocessor. :
    (7) Indoor fan motor speed detection signal. In order to accurately control the indoor fan motor speed, the fan motor must
feed back a running speed signal to the microprocessor. This signal is generated by the Hall element of the indoor fan motor, amplified by the transistor DQ2 via CHrr and then
input from the @ pin of the microprocessor.
    4． Microprocessor output control
    (1) indicator light control circuit. This circuit is composed of DQ4~DQ6, etc., which are controlled by the @, @, @ pins of the microprocessor respectively.
Among them, the @ foot controls the power light LD31, which is green; the @ foot controls the timing light LD32, which is yellow; the @ foot controls the compressor
operation indicator light LD33. is green. When the corresponding pin of the microprocessor outputs a high level, the virtual indicator light will light up.
    (2) Buzzer control circuit. Buzzer PB, R3, R4, IC3, DQ3 and the @ pin of the microprocessor form a buzzer control circuit.
When the power is turned on and the main chip receives a valid control signal and outputs various commands, the @ pin outputs a low level. After being inverted
twice the PB emits a buzzing sound, indicating that the operation signal has been take over.
    (3) Compressor control circuit. The @ pin of the microprocessor is the compressor work control signal output terminal. The high level output by this pin
is input to IC3 through R27. After being inverted, it outputs a low level to energize the RL1 relay coil and its contacts are closed, which is compression. power supply; otherwise, the compressor
does not work.
    (4) Indoor and outdoor fan motor control circuit. The @ and @ pins of the microprocessor are the indoor fan motor and outdoor fan motor
control terminals respectively. When the @ and @ pins output low-level control signals according to the set value, the light-emitting tube of the optocoupler thyristor emits a pulse signal. The optocoupler thyristor
controls the operation of the indoor and outdoor fan motors according to the instructions of the microprocessor. The @ pin of the microprocessor is the indoor fan motor speed detection
end. The speed signal detected by the Hall element is input to the @ pin of the microprocessor through DQ2, so that the microprocessor controls
the speed of the indoor fan motor.
    (5) Four-way valve control circuit. The ④ pin of the microprocessor is the control end of the four-way valve. In cooling mode, this pin outputs low level, and then
outputs high level after being inverted by IC3. There is no current in the coil in RL2, and the four-way valve does not operate: during heating mode. Contrary to the above control process, pin ④ outputs
high level, relay RL2 is closed, and the four-way switch reverses direction due to receiving power.
    (6) The air deflector control circuit uses the @, ⑤, ⑦, and @ pins of the microprocessor to control the swing of the air deflector. When the wind deflector is set to
swing state with the remote control, the @, @, ⑦, ⑧ pins output high level in sequence, and then output low level in sequence after being inverted by IC3, so that the four coils of the swing
motor LP sequentially It works when there is electricity, but not when it is not.
    5. Protection circuit
    The protection circuit of the air conditioner includes an overcurrent protection circuit composed of CTI, etc. and an overload protector installed on the top of the compressor.