Abstract: An air conditioning system and a defrosting control method and device thereof including: obtaining defrosting exit time determined in previous defrosting, and controlling the air conditioning system to perform this defrosting according to the defrosting exit time determined in the previous defrosting; in this defrosting process of the air conditioning system, obtaining the temperature of an outdoor environment, and obtaining the temperature of an outlet of an outdoor heat exchanger; determining the temperature of the outdoor environment and the temperature of the outlet of the outdoor heat exchanger; and if the temperature of the outlet of the outdoor heat exchanger is lower than a first preset temperature and lasts a preset time and the temperature of the outdoor environment is lower than a second preset temperature, obtaining forced defrosting time serving as the defrosting exit time of the next defrosting of the air conditioning system, and storing the time.

Abstract: A multi-unit air conditioning system includes an outdoor unit, a first indoor unit, a second indoor unit, a third indoor unit, and a mode conversion device. The outdoor unit includes an outdoor-unit controller and a selector. The first indoor unit includes a first indoor-unit controller. The second indoor unit includes a second indoor-unit controller. The selector is configured to send a first selection signal or a second selection signal. The outdoor-unit controller is configured to control the outdoor unit, the first indoor-unit controller and the second indoor-unit controller to operate under a first control mode according to the first selection signal. The outdoor-unit controller is configured to control the outdoor unit, the first indoor-unit controller and the second indoor-unit controller to operate under a second control mode according to the second selection signal.

Abstract: Disclosed are an air conditioning system and its pressure ratio control method and device. The method includes: acquiring an actual pressure ratio of the compressor every preset time period in operation of the air conditioning system; judging whether the actual pressure ratio is greater than or equal to the first pressure ratio corresponding to a current level; controlling the compressor to downshift one level for operation if the actual pressure ratio is greater than or equal to the first pressure ratio corresponding to the current level; further judging whether the actual pressure ratio is less than the second pressure ratio corresponding to the current level if the actual pressure ratio is less than the first pressure ratio corresponding to the current level; and controlling the compressor to upshift one level for operation if the actual pressure ratio is less than the second pressure ratio corresponding to the current level.

Abstract: Provided are a control method and control device of an air conditioner and an air conditioner. The control method of the air conditioner includes: when a starting capacity of an indoor unit is lower than or equal to a capacity threshold value and a low-voltage protection signal is received, an opening degree of an electronic expansion valve is adjusted. By applying the technical solution provided in embodiments of the present disclosure, when the starting capacity of the indoor unit is low, a shutdown of the air conditioner caused by a false alarm of the low-voltage protection signal due to the fact that an operating load of the air conditioner is low and the opening degree of the electronic expansion valve is low can be avoided, frequent false shutdown caused by the fact that the starting capacity of the indoor unit of the air conditioner is low is avoided, the reliability of the air conditioner can be effectively improved, and the comfort of a user for using the air conditioner is further improved.

Abstract: The control method and system for the variable-frequency compressor includes: acquiring an operation current and an operation frequency of the variable-frequency compressor; determining that the operation current is greater than or equal to a preset frequency-limited current, and reducing the operation frequency to a preset frequency-limited frequency so as to enable the variable-frequency compressor to enter a frequency-limited mode; detecting an operation current at the moment of the variable-frequency compressor every preset duration; determining that the operation current at the moment meets a preset up-conversion condition, and increasing an operation frequency at the moment of the variable-frequency compressor by a preset up-conversion frequency step size until the variable-frequency compressor retreating from the frequency-limited mode; and determining that the operation current at the moment does not meet the preset up-conversion condition, and controlling the variable-frequency compressor to maintain

Abstract: It is provided a cold-air-avoidance control method and apparatus of an indoor unit of a multi-split air conditioning system, the multi-split air conditioning system includes an outdoor unit and a plurality of indoor units, and the cold-air-avoidance control method includes: obtaining a saturation temperature corresponding to a high pressure of the outdoor unit; obtaining an entrance temperature and a return air temperature of a heat exchanger of each heating indoor unit, and controlling an operating status of the heating indoor unit according to the saturation temperature, the entrance temperature and the return air temperature. With the method according to the present disclosure, reliability and accuracy of controlling the heating indoor unit can be improved, such that the effect of the cold-air-avoidance control is improved, and a more comfortable heating process is provided.

Abstract: Provided are a control method and control device of an air conditioner and an air conditioner. The control method of the air conditioner includes: when a starting capacity of an indoor unit is lower than or equal to a capacity threshold value and a low-voltage protection signal is received, an opening degree of an electronic expansion valve is adjusted. By applying the technical solution provided in embodiments of the present disclosure, when the starting capacity of the indoor unit is low, a shutdown of the air conditioner caused by a false alarm of the low-voltage protection signal due to the fact that an operating load of the air conditioner is low and the opening degree of the electronic expansion valve is low can be avoided, frequent false shutdown caused by the fact that the starting capacity of the indoor unit of the air conditioner is low is avoided, the reliability of the air conditioner can be effectively improved, and the comfort of a user for using the air conditioner is further improved.

Abstract: Provided are a control method and a control system for a variable-frequency compressor, an air conditioner and a computer readable storage medium.

Abstract: Disclosed are an air conditioning system and its pressure ratio control method and device. The method includes acquiring an actual pressure ratio of the compressor every preset time period in operation of the air conditioning system; judging whether the actual pressure ratio is greater than or equal to the first pressure ratio corresponding to a current level; controlling the compressor to downshift one level for operation if the actual pressure ratio is greater than or equal to the first pressure ratio corresponding to the current level; further judging whether the actual pressure ratio is less than the second pressure ratio corresponding to the current level if the actual pressure ratio is less than the first pressure ratio corresponding to the current level; and controlling the compressor to upshift one level for operation if the actual pressure ratio is less than the second pressure ratio corresponding to the current level.

Abstract: Disclosed is an air conditioner oil return control method, which includes the steps of: detecting that a power-on operation state of an outdoor unit at present meets a preset condition and a duration of the power-on operation state reaches a first preset duration, controlling the outdoor unit to perform an oil return operation, and setting the start-stop times as an initial value; after completing the oil return operation, detecting whether a start-stop operation occurs in the outdoor unit; updating the start-stop times when the start-stop operation occurs in the outdoor unit; and when updated start-stop times reach a preset number and the outdoor unit is in a starting operation state at present, controlling the outdoor unit to perform the oil return operation. Also disclosed are an air conditioner and a computer readable storage medium.

Abstract: It is provided a cold-air-avoidance control method and apparatus of an indoor unit of a multi-split air conditioning system, the multi-split air conditioning system includes an outdoor unit and a plurality of indoor units, and the cold-air-avoidance control method includes: obtaining a saturation temperature corresponding to a high pressure of the outdoor unit; obtaining an entrance temperature and a return air temperature of a heat exchanger of each heating indoor unit, and controlling an operating status of the heating indoor unit according to the saturation temperature, the entrance temperature and the return air temperature. With the method according to the present disclosure, reliability and accuracy of controlling the heating indoor unit can be improved, such that the effect of the cold-air-avoidance control is improved, and a more comfortable heating process is provided.

Abstract: A controlling method of a multi-unit air conditioning system in the present disclosure includes: S1: sending a first selection signal, or a second selection signal; S2: controlling the multi-unit air conditioning system to operate under a first control mode according to the first selection signal; S3: controlling the multi-unit air conditioning system to operate under a second control mode according to the second selection signal; S4: receiving a mode-on signal; S5: determining whether a second operating mode is the same as the first operating mode, if no, entering step S6; S6: turning on an indoor-unit fan of the first indoor unit and sending a mode conversion signal to the outdoor-unit controller; S8: converting an operating mode of the outdoor unit; S9: controlling the first indoor unit to operate under the first operating mode; S10: controlling operation of the second indoor unit according to the parameters of the first operating mode.