The invention relates to an air source
heat pump unit capable of realizing continuous
heat supply. The air source
heat pump unit comprises a compressor unit, an indoor water heat exchange unit, a quasi-second-stage compression unit, an outdoor air heat exchange unit and a
defrosting branch unit. According to the air source
heat pump unit disclosed by the invention, the new technical scheme of quasi-second-stage compression, water-side double-stage heat exchange, and multi-
branch heat taking and alternating
defrosting, of an air source heat pump under the working condition of low environment temperature is adopted, firstly, a compressor is additionally provided with an air supplementing port, and a middle
plate heat exchanger is additionally arranged in a
system, so as to form heat pump circulation with the quasi-second-stage compression; secondly, double-stage heat exchange is adopted for the indoor water heat exchange unit, and two stages of heat exchangers are arranged, so as to furthest increase the temperature of circulating water, and the temperatures of supply and return water; and finally, an outdoor air
heat exchanger of the air source heat pump is configured to be at leasttwo branched heat taking and
defrosting systems capable of independently running, and defrosting operation is carried out on a
fluorine-air heat exchange mechanism in each
branch in an alternating manner one by one, so that alternating accurate defrosting and continuous
heat supply are realized.