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4.21 Outline of electronic expansion valve (EEV) control:
(1) Overview:
① Initial control: When the power is ON and the reference position is determined, the EEV opening is
widened within 5 minutes to let the refrigerant return, thus makes the low pressure rise easily and
avoid misdiagnosis of insufficient refrigerant and poor EEV operation as the low pressure can’t rise
after decline;
② Open loop control: After the initial control, when the temperature measured by the sensor, etc. are
unstable, the EEV opening is set according to the balance of the compressor;
③ Area control: During quasi-steady running and steady running, the EEV opening is set according to
the extent of over heat of exhaust, mainly aiming at the measure for the deviation due to open loop
control;
④ Stop control: The EEV opening is set according to the stop control;
⑤ Negative pressure countermeasure control: When the mode is switched from a mode other than
Heating to the Heating mode, the compressor is changed from OFF to ON, and the outdoor
temperature is too low (temperature measured by discharge pipe sensor (Th0-D) - temperature
measured by outdoor air temp. sensor (Th0-A) < 10℃), this control is executed for 8 minutes to
avoid negative pressure risk;
⑥ Throttle correction control of cooling & drying: Five minutes after the area control, when the actual
rotate speed of the compressor is below 24 rps and the temperature measured by the outdoor air
temp. sensor (Th0-A) meets the condition 25℃≤ Th0-A < 38℃ and the temperature measured by
the indoor heat exchanger sensor (Th1-RX) is above 10℃, this control is executed to increase the
latent heat capacity in cooling;
⑦ Condensation prevention control: When the actual rotate speed of the compressor is above 32 rps
and the value measured by the humidity sensor (HS) is above 68% for 30 minutes continuously, this
control is executed to make the actual rotate speed of the compressor reduce to below 32 rps or
make the value measured by HS reduce to below 63%.
(2) Priority of various EEV controls:
Stop control > Defrosting control > Indoor issued fixed opening control > Initial control > Protective
control > Open loop control and area control
(3) Except the special situations such as reference position control, etc., others are controlled within the
pulse range of 41-47.
4.22 Outline of compressor control:
(1) Overview of ON/OFF of cooling and heating running:
① When the outdoor running mode is Cooling or Heating, the compressor has stopped for over 3
minutes, and the compressor running signal from the indoor unit is received, the compressor will be
turned on;
② When the compressor is ON, the rotate speed of the compressor is fuzzily calculated using the
temperature of the indoor inlet air, the temperature set with the remote controller, the setting
correction temperature, etc., and the outdoor unit sends the compressor ON signal, the value of
fuzzy calculation, the actual rotate speed, etc. to the indoor unit;
③ When the outdoor running mode is Cooling or Heating, the compressor has run for over 5 minutes,
and the compressor stop signal from the indoor unit is received, the compressor will be turned off;
④ When the compressor is OFF, the outdoor unit sends the compressor OFF signal, the value of fuzzy
calculation, the actual rotate speed, etc. to the indoor unit;
⑤ In defrosting control, the compressor OFF conditions are not judged.
(2) Running range: 20-120 rps (varying depending on the model).
(3) In order to prevent the oil level of the compressor from falling and ensure that oil is supplied to the
pump of the compressor normally, enable the protection against temporary rise of rotate speed of
compressor.
(4) In order to guarantee the pressure difference for switching the 4-way valve, enable the low load for
temporary rise of rotate speed of compressor.
(5) With respect to the change rate of the actual rotate speed of the compressor, the instructed rotate speed
from the outdoor inverter to the compressor and the temperature measured by the outdoor heat
exchanger sensor (during cooling) or the temperature measured by the indoor heat exchanger sensor
(during heating) should be observed to decide the rise/fall speed of the compressor (2 rps, 1/2 rps) and
finally make the compressor operate in the appropriate working state.
4.23 Outline of outdoor fan control:
(1) The settings of rotate speed of the outdoor fan are as follows: