Throttle opening degree control method for varied-frequency air-conditioner

Abstract

The invention discloses a throttle opening degree control method for a varied-frequency air-conditioner. The method comprises the following steps of: S1) making an electronic expansion valve standby at the opening degree of P0; S2) determining a frequency band Fn of a compressor frequency value according to the compressor frequency value and a corresponding initial target opening degree Pn; adjusting the opening degree of the electronic expansion valve to be Pn; if the frequency of a compressor is increased, adjusting the opening degree of the electronic expansion valve to be the initial target opening degree corresponding to a real-time frequency; and if the frequency of the compressor is reduced, adjusting the opening degree of the electronic expansion valve to be the initial target opening degree corresponding to the real-time frequency after a delay of 60 seconds; and S3) after the electronic expansion valve is operated for t minutes at the opening degree of Pn, modifying the opening degree of the electronic expansion valve every other m seconds. By the method, the optimum efficiency of the operation of a refrigeration system can be ensured at various frequencies and under various working conditions.

Description

technical field [0001] The invention relates to the technical field of frequency conversion air conditioners, and more specifically relates to a control method for throttling opening of frequency conversion air conditioners. Background technique [0002] In the refrigeration system of the inverter air conditioner, the throttling part is an essential part. Compared with the traditional capillary tube, the electronic expansion valve has the advantages of high flow adjustment accuracy and large adjustment range, which can meet the flow requirements under various working conditions, especially in the inverter air conditioning system, it can control the refrigerant with the change of frequency Inverter air conditioners with low frequency can obtain higher capacity and energy efficiency, so electronic expansion valves are widely used in inverter air conditioners. [0003] In the inverter air conditioning system, most of the existing electronic expansion valve control methods use ...

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Problems solved by technology

[0004] First of all, the compressor of an inverter air conditioner can operate at a low frequency of about 10Hz, or at a high frequency above 100Hz. Under such a wide operating range, there is a large difference in superheat

[0005] Secondly, whether it is an outdoor heat exchanger or an indoor heat exchanger, the flow path generally does not have one in and one out. As long as it is a multi-flow heat exchanger, distribution will inevitably occur when operating in a wide frequency range. However, the temperature sampling only samples one of the flow paths. Obviously, when the refrigerant flow distribution is uneven, the obtained superheat cannot reflect the real situation of the air conditioning system, and the opening control of the electronic expansion valve will deviate, or even appear. The more the adjustment becomes more chaotic, the system energy efficiency will be reduced and the abnormal protection

[0006] In addition, the indoor and outdoor units of inverter air conditioners are at least 3-4 meters apart, and at most 20-30 meters or even farther. The suction temperature is sampled on the outdoor side, and the evaporation side temperature is sampled on the indoor side during cooling. Affected by the external temperature will also cause a large deviation in the sampling of the superheat, which will cause a deviation in the opening control of the electronic expansion valve

[0007] Obviously, the current control method that relies solely on superheat to control the opening of the electronic expansion valve is not the best method for controlling the flow of the inverter air conditioner.

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