Control method of electronic expansion valve in air conditioning system

Abstract

The invention relates to a control method of an electronic expansion valve in an air conditioner system. The control method comprises: (1) detecting intermediate temperature T1 of an evaporator and outlet temperature T2 of the evaporator when the air conditioner system is in a refrigerating mode; and detecting intermediate temperature T4 of a condenser and outlet temperature T5 of the condenser when the air conditioner system is in a heating mode; (2) calculating degree of superheat delta T, wherein the degree of superheat delta T =T2-a*T1+b when the air conditioner system is in the refrigerating mode and the degree of superheat delta T=T5-c*T4+d when the air conditioner system is in a heating mode; (3) detecting outer temperature T3 of the actual environment of the air conditioner system and setting a target degree of superheat delta Tr according to T3; (4) comparing the degree of superheat delta T with the target degree of superheat delta Tr, and enabling the control system to output control signals according to comparison results to exert PID control on the electronic expansion valve. The control method of the electronic expansion valve is convenient and accurate in calculation of the degree of superheat, is low in cost, can meet requirements of one-driven-one constant-speed variable frequency air conditioner systems and is suitable for constant-speed variable frequency multi-split air conditioner systems.

Description

technical field [0001] The invention relates to a method for controlling the opening degree of an electronic expansion valve arranged in an air conditioning system. Background technique [0002] In the prior art, the opening of the electronic expansion valve in the air-conditioning system is usually controlled by PID, and generally there are two main control methods as follows: [0003] 1. The PID closed-loop feedback control method by detecting the exhaust temperature of the compressor, as shown in the attached figure 1 shown. This method requires the evaporator intermediate temperature sensor, indoor suction temperature sensor, outside air temperature sensor, condenser intermediate temperature sensor, and exhaust temperature sensor to detect the evaporator intermediate temperature, indoor temperature, outdoor temperature, and condenser intermediate temperature. compressor discharge temperature. Firstly, the discharge temperature T of the compressor is detected, and then...

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Problems solved by technology

[0005] For the above method 1, it has the following defects: (1) The calculation of the target exhaust temperature Tr is relatively complicated; (2) If the air conditioning system is multi-connected and the electronic expansion valve is on the side of the indoor unit, this control method cannot meet the control requirements ; (3) This control method is a fuzzy control method, which requires more experiments to simulate the target exhaust temperature Tr, and its accuracy is low

As for the above method 2, it has the following disadvantages: (1) It needs a pressure sensor to detect the suction pressure of the compressor, and the cost is high; (2) If the air conditioning system is a frequency conversion side, the control method cannot meet the control requirements

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