Control method and system for opening degree of electronic expansion valve, and electrical equipment

Abstract

The invention relates to a control method and system for the opening degree of an electronic expansion valve, and electrical equipment. The control method comprises the following steps: the opening degree of the electronic expansion valve is obtained according to compressor performances and required working conditions of operation; the electronic expansion valve is opened according to pre-opening degree, and a preset time is kept; when the preset time is reached, whether pre-opening degree adjusting conditions are met or not is judged, if the pre-opening degree adjusting conditions are met, adjustment and control are performed on the pre-opening degree of the electronic expansion valve according to preset rules until a pre-opening degree exit condition is met, and the electronic expansion valve is controlled for automatic adjustment; if the pre-opening degree adjusting conditions are not met, the electronic expansion valve is directly controlled for automatic adjustment. According to the method provided by the invention, in the starting of a machine set, the system is enabled to be stable as fast as possible, and unnecessary fluctuations are reduced, so as to enable the machine set to be transited into a stable state smoothly.

Description

technical field [0001] The invention relates to the technical field of electronic expansion valves, in particular to a method, system and electrical equipment for controlling the pre-opening degree of an electronic expansion valve. Background technique [0002] Compared with the mechanical throttling device, the electronic expansion valve has great advantages. Although the cost will be relatively high, it avoids the cumbersome and unstable adjustment of the mechanical device, and also increases the flexibility of control. Electronic expansion valves have been widely used in large central air conditioners. The electronic expansion valve control method widely adopts PID control, which is adjusted according to the target value and change trend of the suction superheat or exhaust superheat, so that the system suction superheat or exhaust superheat is finally stabilized near the target value, but when the unit starts At this time, the opening speed of the electronic expansion va...

AI Technical Summary

Problems solved by technology

The electronic expansion valve control method widely adopts PID control, which is adjusted according to the target value and change trend of the suction superheat or exhaust superheat, so that the system suction superheat or exhaust superheat is finally stabilized near the target value, but when the unit starts At this time, the opening speed of the electronic expansion valve is affected, resulting in insufficient opening, and the temperature changes slowly and the pressure changes quickly, which makes the adjustment of the superheat degree distorted, and the superheat degree can only stabilize after a period of time after a large fluctuation. The common method is to fix the electronic expansion valve in advance before starting. Expansion valve opening, followed by PID control

[0003] However, the fixed opening has limitations, because under some working conditions, especially under some extreme working conditions, the fixed opening value may deviate from the actual needs, or the opening is not enough or the opening is too large, especially When the unit is started at low temperature or frequently started, the fluctuation of the opening of the electronic expansion valve may seriously affect the operation of the unit, resulting in low pressure of the unit or waiting for liquid.

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