Heat pump system and control method thereof

A heat pump system, comprising:

• a heat-source-side heat exchanger on a first flow path;
• a user-side heat exchanger on a second flow path;
• a first three-way valve and a second three-way valve arranged in parallel between the first flow path and the second flow path, wherein the first three-way valve has a first port and a second port for communicating with the first flow path and a third port for communicating with the second flow path, and the second three-way valve has a first port and a second port for communicating with the first flow path and a third port for communicating with the second flow path;
• and
• an economizer and a throttling device connected in turn between the second port of the first three-way valve and the second port of the second three-way valve, wherein the economizer and the throttling device are operably connected between the heat-source-side heat exchanger and the user-side heat exchanger.

A heat pump system, comprising:

• a heat-source-side heat exchanger on a first flow path;
• a user-side heat exchanger on a second flow path;
• a four-way valve arranged between the first flow path and the second flow path, wherein the four-way valve has a first port and a second port for communicating with the first flow path, and a third port and a fourth port for communicating with the second flow path;
• and
• an economizer and a throttling device connected in turn between the second port and the fourth port of the four-way valve, wherein the economizer directly communicates with the second port of the four-way valve.