Frequency conversion control method for heat pump water heater

Abstract

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.

Description

technical field [0001] The invention relates to a control method, specifically a frequency conversion control method, especially a frequency conversion control method for a heat pump water heater. Background technique [0002] The fixed-frequency air source heat pump water heater is realized by controlling the start and stop of the compressor. When the temperature of the water tank reaches the set value, the compressor stops running; Start hot water. The obvious disadvantage of this control method is that the compressor starts frequently, and the starting current is large, which will have a large impact on the grid voltage. [0003] Moreover, the fixed-frequency air source heat pump water heater is generally above 35 degrees in a high temperature environment, and even above 40 degrees in some areas, and the low-pressure pressure can reach 0.7MPa or even 0.9MPa. If the suction temperature of the compressor is too high, the volume coefficient will decrease, and it is more li...

AI Technical Summary

Problems solved by technology

The obvious disadvantage of this control method is that the compressor starts frequently, and the starting current is large, which will have a large impact on the grid voltage.

[0003] Moreover, the fixed-frequency air source heat pump water heater is generally above 35 degrees in a high temperature environment, and even above 40 degrees in some areas, and the low-pressure pressure can reach 0.7MPa or even 0.9MPa. If the suction temperature of the compressor is too high, the volume coefficient will be reduced, and it is more likely to cause damage to the compressor

[0004] In addition, the heating capacity of the fixed-frequency air source heat pump at low temperatures decreases with the decrease of the ambient temperature, and the circulation flow decreases. As the temperature of the water tank increases, the exhaust temperature increases and the compression ratio of the compressor increases. If the compressor runs for a long time under the condition of such an excessive compression ratio, the lubricating oil will become thinner or even carbonized and coked, which will eventually cause the compressor to burn out

[0005] At the same time, when the fixed-frequency air source heat pump works at low temperature and runs for a long time, the finned heat exchanger will frost. Due to the small circulation flow at low temperature, the defrosting will not be complete, and ice will form on the fins for a long time. , seriously affect the heat exchange, and even cause low pressure protection in severe cases, so that the compressor stops and cannot make hot water