Multi F Four-Way Ceiling Cassette Service Manual

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Only for training and service purposes

LGE Internal Use Only

Part 3 Basic Control

Basic principle is to control the rpm of the motor by changing the working frequency of the compressor.

Three phase voltage is supplied to the motor and the time for which the voltage will supplied is controlled by IPM

(intelligent power module).

Switching speed of IPM defines the variable frequency input to the motor.

1. Normal operation

Fuzzy control : Maintain evaporating temperature (Te) to be constant on cooling mode and constant condensing temper-

ature (Tc) on heating mode by fuzzy control to ensure the stable system performance.

2. Compressor control

Cooling and heating load

System capacity

Linear control

Inverter linear control as cooling and heating load increasing

Actuator Cooling operation Heating operation Stop state

Compressor Fuzzy control Fuzzy control Stop

Fan Fuzzy control Fuzzy control Stop

EEV

Super heating

fuzzy control

Super heating & Sub cooling

fuzzy control

Min. Pulse

EEV operates with fuzzy control rules to keep the degree of superheat (about 2~3℃) at the evaporator outlet status.

The degree of superheat = Tsuction – Tevaporation

Tsuction : temperature at suction pipe sensor(℃)

Tevaporation : evaporation temperature (℃)

3. EEV( Electronic Expansion Valve) control

※ 14,16k Models

Frequency that corresponds to each rooms capacity will be determined according to the difference in the tempera-

ture of each room and the temperature set by the remote controller.

There are various factors determining the frequency.

※ 14, 16k Models

Capacity steps of compressor are decided by summation of capacity code, outdoor temp., indoor temp., step com-

pensation of temperature difference indoor temp. and setting temp.

※ 14, 16k Models

EEV operates with PI control rules to keep the degree of superheat at the evaporator inlet and outlet status.