Multi-connected system and its control method

Abstract

The invention discloses a multi-online system and a control method thereof. The control method comprises the following steps that when the outdoor environment temperature is smaller than first preset temperature and the starting total capacity of the multi-online system operating in a pure refrigeration mode is smaller than first preset capacity, the exhaust superheating degree of a compressor is obtained; whether the exhaust superheating degree is smaller than first preset superheating degree or not is judged; if the exhaust superheating degree is smaller than the first preset superheating degree and continues for first preset time, an outdoor fan is controlled to be turned off, and the opening degrees of a first throttling element and a second throttling element are controlled and adjusted to be small; the opening degree of the indoor throttling element of an inner refrigeration unit in a startup mode is controlled to preset initial opening degree through. By the adoption of the method, the inner refrigeration unit is not frequently switched to a freezing-prevention mode by decreasing the refrigerant amount flowing through the started inner refrigeration unit and decreasing the liquid state refrigerant flowing back to the outdoor unit as much as possible, a very good refrigeration effect is achieved, and it is ensured that the compressor has a safer exhaust superheating degree state.

Description

technical field [0001] The invention relates to the technical field of air conditioners, in particular to a control method of a multi-connection system and a multi-connection system. Background technique [0002] The multi-connected system has four modes: pure cooling, pure heating, main cooling and main heating. Among them, the main cooling mode and the main heating mode can use the condensation heat and evaporation heat of the system at the same time, which greatly improves the energy efficiency of the system. [0003] However, when the system is running in pure cooling mode, when the outdoor temperature and indoor temperature are relatively low, and the system load is relatively small, it will lead to frequent anti-freeze standby of the cooling indoor unit, the risk of liquid compression of the compressor, and the long-term no discharge of the compressor. Gas superheat and other issues will affect the reliability of the system. Contents of the invention [0004] The p...

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Problems solved by technology

[0003] However, when the system is running in pure cooling mode, when the outdoor temperature and indoor temperature are relatively low, and the system load is relatively small, it will lead to frequent anti-freeze standby of the cooling indoor unit, the risk of liquid compression of the compressor, and the long-term no discharge of the compressor. Gas superheat and other issues, thus affecting the reliability of the system

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