HEAT PUMP WATER HEATER UNIT AND CONTROL METHOD AND DEVICE THEREOF
FIG4 is a diagram illustrating the logic of a control method of a heat pump water heater unit according to another embodiment of the present disclosure
As illustrated in FIG4, when TS≥Tstop, the case that that the water of the water tank can be heated to the set temperature TS within the total time period H of the off-peak electricity when the heat pump host is turned on alone may not occur, and a case that, when both the heat pump host and the electric auxiliary heater is turned on, the water temperature of the water tank has not reached the set temperature TS while a temperature of the heat pump host has reached Tstop. At this time, the electric auxiliary heater is required to be turned on alone to continue heating the water in the water tank, such that the water temperature of the water tank can be heated to the set temperature TS within the total time period H of the off-peak electricity. That is, when TS≥Tstop, there may be two kinds of heating conditions. One is turning on the heat pump host alone for a while, then turning on both the electric auxiliary heater and the heat pump host. The other is turning on the heat pump host alone for a while, then turning on both the electric auxiliary heater and the heat pump host for a while, and finally controlling the electric auxiliary heater alone to be turned on for a while. Therefore, in this case, when calculating the first time period t, the heating condition when the electric auxiliary heater is turned on alone may be taken into consideration. For example, the remaining total time period H' of the off-peak electricity can be calculated according to a time period tde required for the water temperature of the water tank to rise by the first pre-set temperature when the electric auxiliary heater is turned on alone. For example, the remaining total time period H' of the off-peak electricity=H∗60- tde∗(TS-Tstop)-n∗TM. Then, the first time period t can be calculated according to the remaining total time period H' of the off-peak electricity, the maximum heating temperature Tstop of the heat pump host at the current outdoor ambient temperature, the water temperature T5 of the water tank. For example, the first time period t=H'/(Tstop-T5)=[H∗60-tde∗(TS-Tstop)-n∗TM]/(Tstop-T5).
diagram
5
difference temperature can be
2
pages
10
heat pump host
20
electric auxiliary heater
['1. A control method of a heat pump water heater unit, wherein the heat pump water heater unit comprises a heat pump host (10), an electric auxiliary heater (20) and a water tank (30), the control method comprises: after receiving an off-peak electricity signal, obtaining a water temperature of the water tank (30) and determining whether the water temperature of the water tank (30) is less than a set temperature; when the water temperature is less than the set temperature, controlling the heat pump host (10) to be in a turned-on state; calculating, every first pre-set time period, a time period required for the water temperature of the water tank (30) to rise by a first pre-set temperature when both the heat pump host (10) and the electric auxiliary heater (20) are turned on, and recording the time period as a first time period; determining whether the first time period is less than a second pre-set time period; and when the first time period is less than the second pre-set time period, controlling the electric auxiliary heater (20) to be in the turned-on state;  characterized in that  the control method comprises: calculating, every first pre-set time period, the time period required for the water temperature of the water tank (30) to rise by the first pre-set temperature when both the heat pump host (10) and the electric auxiliary heater (20) are turned on comprises: determining whether the set temperature is less than a maximum heating temperature of the heat pump host (10) at a current outdoor ambient temperature; when the set temperature is less than the maximum heating temperature of the heat pump host (10) at the current outdoor ambient temperature, calculating a remaining total time period of the off-peak electricity according to the first pre-set time period, and calculating the first time period according to the remaining total time period of the off-peak electricity, the set temperature, and the water temperature of the water tank (30); when the set temperature is greater than or equal to the maximum heating temperature of the heat pump host (10) at the current outdoor ambient temperature, calculating the remaining total time period of the off-peak electricity according to the first pre-set time period and a time period required for the water temperature of the water tank (30) to rise by the first pre-set  temperature when the electric auxiliary heater (20) is turned on alone, and calculating the first time period according to the remaining total time period of the off-peak electricity, the maximum heating temperature of the heat pump host (10) at the current outdoor ambient temperature, and the water temperature of the water tank (30).']