Control method for oil return of DC inverter compressor

Abstract

The invention discloses a control method for oil return of a DC inverter compressor, which comprises the following steps of: (1) initially supplying power to start the machine, and setting the opening of an electronic expansion valve according to the number of the started indoor units; (2) adopting different upconvert methods according to the target frequency of the compressor; (3) if an air conditioning unit starts for 10 minutes, starting oil return circulation; and (4) after oil return, if the machine is in a heating mode, judging whether the temperature of an outdoor coil is less than or equal to -12DEG C, if so, beginning defrosting circulation, and starting a conventional automatic adjustment mode after defrosting, otherwise, starting the conventional automatic adjustment mode, and if the machine is not in the heating mode, directly starting the conventional automatic adjustment mode; and (5) when a stop command is received, adopting different stop modes according to different operating frequencies of the compressor. Compared with the conventional methods, the method has the characteristic of effectively solving the problem of oil starvation in the starting process, normally running process and stopping process of the compressor.

Description

Technical field: [0001] The invention relates to a method for controlling the oil return of a DC frequency conversion compressor, in particular to a method for controlling the oil return of a DC frequency conversion compressor used in a VRV air conditioning system. Background technique: [0002] The full name of the VRV air-conditioning system is Varied Refrigerant Volume, referred to as VRV. It is a variable refrigerant flow air-conditioning system. It uses refrigerant as the delivery medium. An indoor unit consisting of a direct evaporative heat exchanger, throttling device and fan. An outdoor unit can deliver refrigerant liquid to several indoor units through pipelines. By controlling the refrigerant circulation volume of the compressor and the refrigerant flow rate entering the indoor heat exchangers, the indoor cooling and heating load requirements can be met in real time. The VRV system has many advantages such as energy saving, comfort, and stable operation, and each...

AI Technical Summary

Problems solved by technology

At this time, the operating frequency of the DC inverter compressor suddenly rises sharply from low frequency to high frequency, which will cause a large amount of lubricating oil in the oil pool of the compressor to be thrown out of the compressor, resulting in a shortage of oil in the compressor;

[0004] 2. Under the condition of extremely low outdoor temperature (below -15°C) in winter, if the air conditioner unit is turned on after a long shutdown, the lubricating oil in the oil pool of the compressor will also be discharged from the compressor within a period of time after the startup , causing the compressor to lack oil;

[0005] 3. Turn on one indoor unit after sleeping for a long time at low temperature (below 2°C). If the load of this indoor unit is also low (below 30%), since the opening degree of the corresponding electronic expansion valve is set at 150 step or 200 steps, after the compressor is turned on, the lubricating oil in the compressor is discharged more, and the lubricating oil returned to the compressor is less, which will also cause the compressor to lack oil;

[0006] 4. When the indoor temperature of the DC inverter VRV air conditioning system needs to be shut down after reaching the set temperature, the operating frequency of the compressor will drop directly from high frequency to zero frequency, which will also cause the compressor to lack oil