Heat pump system and control method thereof

A heat pump system, comprising:

• a compressor;
• a first flow path, which comprises a first end of the first flow path, a first heat exchanger, a first throttling device, and a second end of the first flow path in sequence;
• a second flow path, which comprises a first end of a second flow path, a second heat exchanger, a second throttling device, and a second end of the second flow path in sequence;
• a third flow path, which comprises a first end of the third flow path, a third heat exchanger, a first check valve, and a second end of the third flow path in sequence, wherein the first check valve on the third flow path only allows a fluid flowing in a direction toward the second end of the third flow path to pass through;
• wherein the second end of the first flow path, the second end of the second flow path and the second end of the third flow path are connected;
• a switching assembly, which can be switched between any two, three or four of the following connection modes:
• a first connection mode, in which the first end of the first flow path is connected to an outlet of the compressor, and the first end of the second flow path is connected to an inlet of the compressor;
• a second connection mode, in which the first end of the second flow path is connected to the outlet of the compressor, and the first end of the first flow path is connected to the inlet of the compressor;
• a third connection mode, in which the first end of the third flow path is connected to the outlet of the compressor, and the first end of the first flow path is connected to the inlet of the compressor;
• and
• a fourth connection mode, in which the first end of the third flow path is connected to the outlet of the compressor, and the first end of the second flow path is connected to the inlet of the compressor;
• and
• a control system, which enables the heat pump system to operate in any two, three, or four of a cooling mode, a heating mode, a hot water preparing mode, and a cooling heat recovery mode;
• in the cooling mode, the switching assembly is switched to the first connection mode, the first throttling device plays a throttling function, and the second throttling device is fully opened or bypassed;
• in the heating mode, the switching assembly is switched to the second connection mode, the first throttling device plays a throttling function, and the second throttling device is bypassed;
• in the hot water preparing mode, the switching assembly is switched to the third connection mode, the first throttling device plays a throttling function, and the second throttling device is in a closed state;
• and
• in the cooling heat recovery mode, the switching assembly is switched to the fourth connection mode, the second throttling device plays a throttling function, and the first throttling device is in a closed state.