| 摘要 |
<p>A heat pump system comprises a rectifier 10, a variable frequency inverter 14, an AC motor 17, and a heat pump circuit including a compressor 18, an evaporator 30 and a condensor 26. The condensor 26 forms part of a heat exchanger 35 associated with a central heating system. The system described also includes an air temperature control circuit 40, a circuit 42 for controlling the water temperature of the central heating system, and a defrosting control circuit 41 capable of detecting frosting. The outputs of these circuits are connected to the frequency control terminal of the inverter 14 through a soil start circuit 47. In operation, the frequency of inverter 14 is controlled so as to vary the speed of the compressor to achieve a desired air temperature and the soil start circuit limits the rate at which the frequency increases so as to keep the input current below a set value. When frosting is detected, the direction of refrigerent flow is reversed by a valve 20 and the speed of motor 17 is increased. Motor 17 is stopped if the water temperature exceeds a limit value. <IMAGE></p> |
