A multi-split system and a liquid return prevention control method thereof during defrosting of the multi-split system. The method includes the following steps: when the multi-split system is in heating operation, detecting gas exhaust pressure (PC), gas return pressure (PE) and gas exhaust temperature (TP) of a compressor in real time; if an outdoor unit receives a defrosting instruction, sending a defrosting signal to a diverter and heating indoor units in multiple indoor units, controlling, by means of the diverter, a throttling element (EXV2) to close before first reversing of a four-way valve and last for a pre-set time, so as to reduce the amount of a refrigerant returned to the outdoor unit; and regulating the opening of the throttling element (EXV2) according to the gas exhaust pressure (PC), gas return pressure (PE) and gas exhaust temperature (TP) during defrosting operation of the multi-split system, so that the risk of liquid return occurred to the compressor during a defrosting process, and the safety and reliability of the system are greatly improved.

The present invention relates to an outdoor system for an air conditioner. In an air conditioner which comprises at least one outdoor system, the at least one outdoor system comprises: a compressor; an outdoor heat exchanger; a pair of two-stage compression lines extending to the outside of the outdoor system; a pair of connection lines extending to the outside of the outdoor system and communicating with an indoor unit; and multiple valves for opening/closing the pair of two-stage compression lines and the pair of connection lines when the outdoor system is operated in a one-stage heating mode or two-stage heating mode.

In a motor driving apparatus having an inverter which can drive n (n being an integer not smaller than 2) motors each having a permanent magnet in its rotor, and a connection switching device for switching the connection state of the n motors, the connection switching device is operated to change the number of the motors connected to the inverter thereby to change the impedance as seen from the inverter towards the motors. When i (i being any of 2 to n) motors among the n motors are concurrently driven by the inverter, the voltage outputted by the inverter may be controlled such that the inductance values of the i motors are identical. It is possible to prevent hunting and step-out due to the phase difference between the motors driven by the inverter.

A system comprising a compressor, a first valve coupled to the compressor and coupled to a first coil, a first expansion valve coupled to the first coil, a second coil, and a second expansion valve. The second expansion valve coupled to a third coil, a second valve coupled to the compressor and the third coil. A controller operable to operate the first valve, the first expansion valve, the second expansion valve, and the second valve. The second coil is coupled to the compressor and the refrigerant flows from the second coil to the compressor.

Heat pump system (100) comprising at least one heat medium circuit (210,220,230,240,250,310,320,410,420,430,440,450,460) in turn comprising a compressor (211), an expansion valve (232,242), at least two different primary heat sources or sinks selected from outdoor air, a water body, the ground or exhaust air, at least one of two different secondary heat sources or sinks selected from indoors air, pool water and tap water, a respective temperature sensor (412,432) at each of said primary heat sources or sinks, a valve means (421,431,451) for selectively directing the primary-side heat medium to at least one of said primary heat exchanging means, and a control means (500). The invention is characterised in that, in a secondary-side heating operating mode, the temperature of said primary heat sources or sinks is measured, and in that the primary-side heat medium is directed only to available primary heat exchanging means associated with the heat sources or sinks with the highest temperature. The invention also relates to a method.

An air conditioner is disclosed. The air conditioner comprises: an indoor unit having an indoor heat exchanger installed therein; a first outdoor unit having a first outdoor heat exchanger and a first compressor installed therein; a second outdoor unit having a second outdoor heat exchanger and a second compressor installed therein; an auxiliary module which connects the indoor unit, the first outdoor unit, and the second outdoor unit; a first connection line by which the auxiliary module is connected to the first outdoor unit; a second connection line by which the auxiliary module is connected to the second outdoor unit; and a two-stage compression line by which the first outdoor unit is connected to the second outdoor unit.

Provided is an air conditioning apparatus. The air conditioning apparatus includes an outdoor unit through which a refrigerant is circulated, an indoor unit through which water is circulated, and a heat exchange device including a heat exchanger in which the refrigerant and the water are heat-exchanged with each other. The heat exchanger includes a high-pressure guide tube, a low-pressure guide tube, a liquid guide tube, a bypass tube configured to connect a bypass branch point of the high-pressure gas tube of the outdoor unit to a bypass combination point of the liquid guide tube to bypass a high-pressure refrigerant existing in the high-pressure tube to the liquid guide tube, and a bypass valve installed in the bypass tube. The outdoor unit includes a first valve device configured to guide a refrigerant compressed in the compressor to the outdoor heat exchanger and a second valve device configured to guide the refrigerant compressed in the compressor to the high-pressure guide tube of the heat exchange device.

An air conditioning apparatus may include an outdoor unit through which a first fluid, such as refrigerant circulates, an indoor unit through which a second fluid, such as water circulates, a heat exchange device which is configured to connect the outdoor unit to the indoor unit and in which the first fluid and the second fluid are heat-exchanged with each other, first to third inner tubes configured to connect the outdoor unit to the heat exchange device, and a heat storage unit connected to the first to third inner tubes.

An air conditioning apparatus may include an outdoor unit through which a first fluid, such as refrigerant circulates, an indoor unit through which a second fluid, such as water circulates, a heat exchange device which is configured to connect the outdoor unit to the indoor unit and in which the first fluid and the second fluid are heat-exchanged with each other, a first inner tube which is configured to connect the outdoor unit to the heat exchange device and through which the first fluid at high-pressure flows, a second inner tube which is configured to connect the outdoor unit to the heat exchange device and through which the first fluid at low-pressure flows, and a third inner tube which is configured to connect the outdoor unit to the heat exchange device and through which the first fluid in liquid form flows. The heat exchange device may include a bypass tube configured to bypass the second inner tube and a flow control valve provided in the bypass tube.

An air conditioner includes an outdoor heat exchanger in which N heat exchange units are spaced apart from one another sequentially in a vertical direction N expansion valves respectively connected to the N heat exchange units; N hot gas pipes respectively connected to the N heat exchange units; N hot gas valves respectively installed in the N hot gas pipes; and a controller configured to control the N expansion valves and the N hot gas valves to defrost the N heat exchange units, wherein the controller is configured to defrost a bottom heat exchange unit first, then defrost a top heat exchange unit, and defrost the heat exchange units located under the top heat exchange unit sequentially from a second highest heat exchange unit to the bottom heat exchange unit after defrosting the top heat exchange unit.