Frequency conversion control method for heat pump water heater

The invention relates to a frequency conversion control method for a heat pump water heater. The frequency conversion control method for the heat pump water heater is characterized by comprising the following steps of: performing frequency conversion control on a compressor of the heat pump water heater; performing frequency conversion control on a throttle mechanism of the heat pump water heater; performing frequency conversion control on a defrosting mechanism of the heat pump water heater; and performing frequency conversion control on an exhaust temperature of the heat pump water heater. The frequency conversion control method for the heat pump water heater has the advantages of high heating speed, few start-stop times, small temperature fluctuation of a water tank and energy conservation. At a high ambient temperature, the frequency of the compressor can be reduced and the circulating flow quantity of a system can be reduced, so that the suction pressure is reduced and the stable operation of the compressor is guaranteed. At a low ambient temperature, the circulating flow quantity of the system is increased by increasing the frequency of the compressor and the opening degree of an electronic expansion valve, the exhaust temperature is reduced and the compression ratio is reduced, so that the compressor can operate stably. In the defrosting process, the defrosting time is greatly shortened by increasing the circulating flow quantity of the system; and the frost can be removed completely, without the problem that the frost is accumulated into ice.