Heat pump and control method therefor

A heat pump, comprising:

• an outdoor unit comprising a compressor for that compresses a first refrigerant, a first outdoor heat exchanger that exchanges heat between the first refrigerant and outdoor air, an expansion mechanism that expands the first refrigerant, and a second outdoor heat exchanger that exchanges heat between the first refrigerant and a second refrigerant;
• a first refrigerant pipe that connects the compressor, the first outdoor heat exchanger, and the expansion mechanism, and through which the first refrigerant flows;
• a pressure sensor disposed in the first refrigerant pipe;
• a second refrigerant pipe that is connected to the second outdoor heat exchanger, and through which the second refrigerant flows;
• an indoor heat exchanger that is disposed in the second refrigerant pipe, and exchanges heat between indoor air and the second refrigerant;
• a controller configured to determine a supply of the second refrigerant by determining a flow rate of the second refrigerant based on surging occurring in a pressure of the first refrigerant measured by the pressure sensor;
• and
• a compressor injection pipe connected to the compressor and a compressor injection valve disposed in the compressor injection pipe, wherein the controller supplies the second refrigerant when the compressor injection valve is not opened.

A heat pump, comprising:

• an outdoor unit comprising a compressor for that compresses a first refrigerant, a first outdoor heat exchanger that exchanges heat between the first refrigerant and outdoor air, an expansion mechanism that expands the first refrigerant, and a second outdoor heat exchanger that exchanges heat between the first refrigerant and a second refrigerant;
• a first refrigerant pipe that connects the compressor, the first outdoor heat exchanger, and the expansion mechanism, and through which the first refrigerant flows;
• a pressure sensor disposed in the first refrigerant pipe;
• a second refrigerant pipe that is connected to the second outdoor heat exchanger, and through which the second refrigerant flows;
• an indoor heat exchanger that is disposed in the second refrigerant pipe, and exchanges heat between indoor air and the second refrigerant;
• a controller configured to determine a supply of the second refrigerant by determining a flow rate of the second refrigerant based on surging occurring in a pressure of the first refrigerant measured by the pressure sensor;
• a boiler which is disposed in parallel with the outdoor unit, and heats a second refrigerant;
• and
• a third refrigerant pipe which connects the boiler and the indoor heat exchanger, and through which the second refrigerant flows, wherein the controller operates the boiler and supplies the second refrigerant to the indoor heat exchanger, when it is determined that the flow rate of the second refrigerant is insufficient.