Heat pump unit control method and device and heat pump unit

The invention discloses a heat pump unit control method and device and a heat pump unit. The heat pump unit control method comprises the steps that the exhaust temperature of a compressor is monitored; if the exhaust temperature is larger than a first preset threshold value, the opening degree of an electronic expansion valve is increased; and the heat exchange temperature difference of an evaporator is obtained, and whether the opening degree of the electronic expansion valve continues to be increased or not is controlled according to the exhaust temperature and the heat exchange temperaturedifference. Unit control is carried out by combining the exhaust temperature of the compressor and the heat exchange condition of the evaporator, the opening degree of the electronic expansion valve can be reasonably controlled in time, unit performance can be exerted easily, the unit heat exchange efficiency can be guaranteed while exhaust temperature control is achieved, and the unit performanceis prevented from being g