Control method and system of variable refrigerant flow (VRF) air conditioner

Abstract

The invention provides a control method and system of a variable refrigerant flow (VRF) air conditioner. The VRF air conditioner comprises an outdoor unit and a plurality of indoor units. An electronic expansion valve is mounted in each indoor unit. The control method includes: when an instruction for turning off all the indoor units of the VRF air conditioner is received, controlling the compressor of the outdoor unit to stop operation, and controlling an optional number of electronic expansion valves in all the indoor units to keep a preset openness; detecting the difference of high pressure and low pressure in the compressor, and/or recording the duration of operation stopping; when the detected pressure difference is smaller than or equal to a preset pressure value and/or the duration of operation stopping reaches preset duration, controlling the four-way valve in the outdoor unit to deenergize. By the control method, when all the indoor units of the VRF air conditioner are turned off, air flow impact noise can be avoided while air conditioner energy consumption can be lowered under the premise that the difference of the high pressure and the low pressure in the compressor is balanced.

Description

technical field [0001] The present invention relates to the technical field of air conditioners, in particular to a control method for a multi-connected air conditioner and a control system for a multi-connected air conditioner. Background technique [0002] At present, in the related art, there are mainly the following two control schemes for turning off all indoor units in the heating mode of the multi-connected air conditioner: [0003] Solution 1: Turn off all indoor units in heating mode, and when the outdoor function needs to be 0 (that is, the outdoor unit compressor stops working), the four-way valve of the outdoor unit will be powered off immediately; [0004] Solution 2: Turn off all indoor units in heating mode, and when the outdoor function is 0, the four-way valve of the outdoor unit remains powered on. [0005] However, in Solution 1, when the outdoor function is set to 0, the four-way valve is cut off immediately, and the high and low pressure inside the comp...

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Problems solved by technology

[0005] However, in Solution 1, when the outdoor function is set to 0, the four-way valve is cut off immediately, and the high and low pressure inside the compressor is switched instantaneously, which will generate very obvious airflow impact noise on the indoor unit, seriously affecting the comfort of users. , specifically, as figure 1 Shown is the time-domain spectrum of the noise from the indoor unit when the air conditioner is on standby, with strong noise at point A

In Scheme 2, since the four-way valve of the outdoor unit is always energized, although the airflow impact noise caused by the instantaneous switching of the four-way valve can be eliminated, the pressure difference between high and low pressure inside the compressor cannot be balanced, resulting in a large start-up load of the compressor. Moreover, the four-way valve is always energized, which will also cause a waste of energy.

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