阅读说明：本技术 热泵热水器除霜控制方法及热泵热水器 (Defrosting control method for heat pump water heater and heat pump water heater ) 是由 梁杰 陈炳泉 黄娟 杜顺祥 徐洪浩 侯梅梅 李羲龙 于 2020-08-27 设计创作，主要内容包括：本发明公开了热泵热水器的除霜控制方法,所述控制方法在环境温度、盘管温度和压缩机启动运行时间均达到预设后,进一步确定压缩机累计运行时间和/或盘管温度降幅,以压缩机累计运行时间和/或盘管温度降幅达到预设作为除霜启动的判断条件。本发明提供的除霜控制方法在现有技术的基础上,根据水箱温度和环境温度进一步确定不同工况下的压缩机累计运行时间,此外还可根据盘管温度的降幅来确定是否启动除霜,所述控制方法可以提升除霜控制的准确性,实现了按需除霜的技术目的,适合推广使用。(The invention discloses a defrosting control method of a heat pump water heater, which further determines the accumulated operation time of a compressor and/or the temperature reduction amplitude of a coil after the environmental temperature, the temperature of the coil and the starting operation time of the compressor reach preset values, and takes the accumulated operation time of the compressor and/or the temperature reduction amplitude of the coil as the judgment condition for starting defrosting. On the basis of the prior art, the defrosting control method further determines the accumulated running time of the compressors under different working conditions according to the temperature of the water tank and the ambient temperature, and can determine whether to start defrosting according to the amplitude of the temperature drop of the coil.)

1. The defrosting control method of the heat pump water heater is characterized in that after the environmental temperature, the coil temperature and the starting operation time of the compressor reach the preset values, the accumulated operation time of the compressor and/or the temperature reduction amplitude of the coil are further determined, and the accumulated operation time of the compressor and/or the temperature reduction amplitude of the coil reach the preset values to serve as judgment conditions for starting defrosting.

2. The defrosting control method of the heat pump water heater according to claim 1, wherein the control method starts defrosting when any one of the judgment conditions is reached first when the judgment conditions are met when the accumulated running time of the compressor reaches a preset value and the temperature reduction amplitude of the coil reaches a preset value at the same time;

preferably, the defrosting is started when the accumulated operation time of the compressor reaches a preset value.

3. The defrosting control method of a heat pump water heater according to claim 2, wherein the accumulated operating time of the compressor is obtained by table lookup and logical operation on the condition that the ambient temperature and the water tank temperature acquired by the heat pump water heater are used.

4. The defrosting control method of a heat pump water heater according to claim 3, wherein the accumulated operating time of the compressor is increased as the temperature of the water tank is increased at the same ambient temperature; under the same water tank temperature, the accumulated running time of the compressor tends to increase firstly and then decrease along with the decrease of the ambient temperature.

5. The defrosting control method of a heat pump water heater according to claim 4, wherein the tank temperature includes a low temperature threshold, a medium temperature threshold and a high temperature threshold, the ambient temperature includes a first threshold, a second threshold and a third threshold, the ambient temperature is gradually decreased, and the cumulative operating time of the compressor is longest when the ambient temperature is at the second threshold and the tank temperature is at the high temperature threshold; and when the temperature of the water tank is not changed, the accumulated running time of the compressor when the ambient temperature is in the first threshold condition is not greater than the accumulated running time of the compressor when the ambient temperature is in the third threshold condition.

6. The defrosting control method of a heat pump water heater according to claim 1, wherein the compressor startup operation time is an operation time of the compressor after the heat pump water heater is started up, and the compressor accumulated operation time includes the compressor startup operation time.

7. The defrosting control method of a heat pump water heater according to claim 2, wherein the accumulated operating time of the compressor is recalculated after each defrosting operation is finished.

8. The defrost control method for a heat pump water heater as recited in claim 2, wherein said decrease in said coil temperature is a decrease in said coil temperature per unit time, said unit time being calculated from a point in time when said ambient temperature, said coil temperature and said compressor startup operation time reach a predetermined value.

9. The defrosting control method of the heat pump water heater according to any one of claims 1 to 8, further comprising a condition of judging defrosting completion when the coil temperature or the defrosting operation time reaches a preset value.

10. A heat pump water heater, comprising: a memory storing an executable program and a processor executing the executable program to implement the defrosting control method of the heat pump water heater according to any one of claims 1 to 9.

Technical Field

The invention belongs to the field of heat pump water heaters, and particularly relates to a defrosting control method of a heat pump water heater.

Background

When the heat pump water heater is used, when the outdoor temperature is low and the humidity is high, the surface of the evaporator is easy to frost, so that the heat exchange is influenced, and the unit cannot run in severe cases. It is therefore necessary to initiate a defrost sequence in the event of frost formation in the evaporator.

The common defrosting control method in the prior art comprises a differential pressure control valve, a temperature difference control method, a temperature time control method and the like, wherein the temperature time control method is the most common method, the setting requirement of the control technology on defrosting parameters is higher, the parameters are single, the judgment is generally carried out through three conditions of outdoor environment temperature, coil pipe temperature and compressor running time, and defrosting action is started when the three conditions meet the conditions. However, as the heat pump water heater operates, the temperature of the water tank rises, and the frosting condition of the outdoor unit is different, for example, the frosting amount is greater than the high water temperature in the case of low water temperature, so the phenomena of non-defrosting, frostless defrosting and the like are easily caused in the prior art.

In view of the above, the present invention is particularly proposed.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a defrosting control method of a heat pump water heater, wherein the control method introduces the accumulated running time of the compressor under different working conditions obtained by calculating the temperature of a water tank and the ambient temperature and the reduction amplitude of the temperature of a coil pipe as judgment conditions on the basis of taking the ambient temperature, the temperature of the coil pipe and the running time of the compressor as judgment basis for starting defrosting in the prior art, thereby realizing the technical purpose of defrosting accurately and according to needs.

In order to solve the technical problems, the invention adopts the technical scheme that:

the invention provides a defrosting control method of a heat pump water heater, which further determines the accumulated operation time of a compressor and/or the temperature reduction amplitude of a coil after the environmental temperature, the temperature of the coil and the starting operation time of the compressor reach preset values, and takes the accumulated operation time of the compressor and/or the temperature reduction amplitude of the coil as the judgment condition for starting defrosting.

In the scheme, after the water heater in the prior art is started and operated for a period of time, the outdoor environment temperature and the evaporator coil temperature are obtained through the sensor, and when the outdoor environment temperature and the evaporator coil temperature are lower than preset values, the evaporator is considered to be frosted to influence heat transfer, so that a defrosting program is started immediately. In fact, after the water heater is started to operate for a period of time, the temperature of the water tank rises to some extent, and the frosting amount on the surface of the outdoor evaporator is reduced to some extent; and because the time period for operating the heat pump water heater is different, the outdoor ambient temperature can also change correspondingly, thereby influencing the frosting amount. Therefore, if the fixed environment temperature, the coil temperature and the running time of the compressor are adopted as defrosting starting conditions, if the temperature of the water tank is higher, defrosting can be started in advance under the condition that a frosting layer of the evaporator does not reach the condition of hindering heat transfer; it is also possible that in the case of low ambient temperature and low tank temperature, a thicker frost layer is formed on the evaporator surface, but the frost formation procedure is not initiated due to insufficient compressor run time. The invention comprehensively considers the factors, takes the accumulated running time of the compressor and the temperature reduction amplitude of the coil as newly increased judgment conditions on the basis of the existing base number, and enables the defrosting starting time to be more refined. The environment temperature is the outdoor environment temperature when the heat pump water heater works, and the coil temperature is the coil temperature of the evaporator.

According to the control method, when the accumulated running time of the compressor reaches the preset value and the temperature reduction amplitude of the coil reaches the preset value at the same time, the control method is used as a judgment condition for starting defrosting, and defrosting is started when any judgment condition is met first; preferably, the defrosting is started when the accumulated operation time of the compressor reaches a preset value.

In the above scheme, under some working conditions, for example, when the ambient temperature changes greatly or the cooling amplitude at night is large, the accumulated running time of the compressor reaches the preset weight and the temperature reduction amplitude of the coil pipe reaches the preset weight, so that the accumulated running time of the compressor and the temperature reduction amplitude of the coil pipe are used as judgment conditions for defrosting starting, and defrosting is started when any one condition is reached. And under other working conditions, for example, when the temperature of the water tank is higher, the accumulated running time of the compressor with larger weight can be used as the judgment basis for starting defrosting.

According to the control method, the accumulated running time of the compressor is obtained by looking up a table and performing logical operation on the condition that the ambient temperature and the water tank temperature acquired by the heat pump water heater are used as conditions.

In the above scheme, the table lookup includes: and obtaining an approximate compressor running time range according to the water tank temperature and the outdoor environment temperature obtained by the heat pump water heater and a table according to the running working conditions of the heat pump water heater under the conditions. The logical operation comprises: and setting different coefficients for the current water tank temperature and the outdoor environment temperature to perform weighting operation, and adding the starting operation time of the compressor to obtain the accumulated operation time of the compressor. The table lookup data and the formula called by the logic operation are stored in a memory of the heat pump water heater and are used when the processor executes the control method.

According to the control method, the accumulated running time of the compressor is increased along with the temperature rise of the water tank under the same environmental temperature; under the same water tank temperature, the accumulated running time of the compressor tends to increase firstly and then decrease along with the decrease of the ambient temperature.

According to the control method, the temperature of the water tank comprises a low temperature threshold, a medium temperature threshold and a high temperature threshold which are gradually increased, the environmental temperature comprises a first threshold, a second threshold and a third threshold which are gradually decreased, and the accumulated running time of the compressor is longest when the environmental temperature is at the second threshold and the temperature of the water tank is at the high temperature threshold; and when the temperature of the water tank is not changed, the accumulated running time of the compressor when the ambient temperature is in the first threshold condition is not greater than the accumulated running time of the compressor when the ambient temperature is in the third threshold condition.

In the scheme, the variation trends of the accumulated running time of the compressor, which are influenced by the temperature of the water tank and the ambient temperature, are different, and the accumulated running time of the compressor is increased along with the rise of the temperature of the water tank under the same ambient temperature; under the same water tank temperature, the accumulated running time of the compressor tends to increase firstly and then decrease along with the decrease of the ambient temperature. Wherein the first threshold, the second threshold, the third threshold, and the low temperature threshold, the medium temperature threshold, and the high temperature threshold all represent a temperature range as shown in the following table:

the accumulated running times a3, a6 and a9 corresponding to the high temperature threshold of the water tank temperature are respectively greater than the accumulated running times corresponding to the low temperature threshold and the medium temperature threshold in the same row on the left side of the table; and when the ambient temperature is at the second threshold, the accumulated running time of the corresponding compressor is longer, so that the accumulated running times of a4, a5 and a6 are respectively larger than the accumulated running times of the first threshold and the second threshold which are in the same column at the upper side and the lower side of the table. The accumulated running time of the compressor determined by the invention is influenced by the temperature of the water tank and the ambient temperature to have certain difference, for example, when the temperature of the water tank is at a high temperature threshold and the ambient temperature is at a second threshold, the time length of the accumulated running time a6 of the compressor is obtained by table lookup and calculation and is greater than the time length of a4, because the temperature of the water tank corresponding to a6 represents the process that the compressor is increased from low to high under the accumulation work, a6 is closer to the preset accumulated running time of the compressor, and at the moment, the frost formation amount is small because the temperature of the water tank is higher; however, if the water tank is operated at a lower temperature, the accumulated running time of the compressor is a4, although a4 is still a period of time away from the accumulated running time of the preset compressor compared with a6, the accumulated running time of the compressor at a lower water temperature is actually included in a6 and is larger in occupation, so that the accumulated running time of the compressor of the heat pump water heater at a low water tank temperature can reach the accumulated running time of the preset compressor more quickly to start defrosting and remove a large amount of frost generated due to the lower water temperature. To illustrate the above process more clearly, in this example, it is assumed that the accumulated operation time corresponding to a6 is 24min, the water tank temperature reaching the high temperature threshold actually rises from the low temperature threshold and the medium temperature threshold, and the compressor operation time is longer at the low temperature threshold, so the accumulated operation time corresponding to a4 is 20min, the accumulated operation time corresponding to a5 is 22min, which includes 20min of the accumulated operation time corresponding to a4 at the low temperature threshold, and if the preset compressor accumulated operation time is 26min, the difference between a4 of the low water tank temperature and a6 of the high water tank temperature reaching the preset compressor accumulated operation time 26min is not large, which can timely clear up a large amount of frost generated by the low water tank temperature operation. In contrast, in the prior art, a fixed defrosting interval is always used as a judgment basis for starting defrosting, in this case, if the water temperature in the water tank is always at a lower level, the frosting amount is large, and the defrosting effect may be poor when the fixed defrosting interval is reached, and if the water temperature in the water tank is always at a higher level, the frosting amount is small, and at this time, the defrosting operation is started when the fixed defrosting interval is reached, so that the consumed energy is large. The prior art does not consider the influence of the temperature of the water tank and the ambient temperature, and the condition that defrosting is started in advance or defrosting is not uniform can be generated.

According to the control method, the starting operation time of the compressor is the operation time of the compressor after the heat pump water heater is started, and the accumulated operation time of the compressor comprises the starting operation time of the compressor.

In the scheme, the ambient temperature and the coil temperature are obtained and whether defrosting is started or not is judged after the heat pump water heater is started to operate for a period of time, so that the preset compressor starting operation time is required to be used as an initial node, the method is further judged from the initial node, and the subsequently calculated accumulated compressor operation time also comprises the compressor starting operation time.

According to the control method, the accumulated running time of the compressor is recalculated after each defrosting is finished.

In the above scheme, because the compressor has intermittent operation under some working conditions, the accumulated operation time of the compressor and the accumulated operation time of the preset compressor are not equal to the defrosting interval.

According to the control method, the temperature drop amplitude of the coil pipe is the drop amplitude of the temperature of the coil pipe in unit time, and the unit time is calculated by the time point when the ambient temperature, the temperature of the coil pipe and the starting running time of the compressor reach preset values.

In the scheme, besides the accumulated running time of the compressor, the temperature reduction amplitude of the coil pipe is introduced as a judgment condition so as to deal with the condition that defrosting is started late only by the accumulated running time of the compressor under certain working conditions; the unit time is the same as the accumulated running time of the preset compressor under certain working conditions.

According to the control method, the control method further comprises the step of taking the temperature of the coil or the defrosting operation time reaching a preset value as a judgment condition for defrosting ending.

The invention also provides a heat pump water heater, comprising: the defrosting control method of the heat pump water heater is realized by the memory with the executable program and the processor executing the executable program.

After adopting the technical scheme, compared with the prior art, the invention has the following beneficial effects:

1. compared with the prior art, the defrosting control method for the heat pump water heater increases the accumulated running time of the compressor and the temperature reduction amplitude of the coil pipe as additional judgment conditions, so that the starting condition of defrosting is more precise, and the technical purpose of defrosting as required is realized;

2. the defrosting control method of the heat pump water heater provided by the invention provides a calculation mode of the accumulated running time of the compressor and a change rule thereof, provides a design scheme suitable for different environments for a defrosting control scheme of the heat pump water heater, and enlarges the application prospect;

3. according to the defrosting control method for the heat pump water heater, the temperature reduction amplitude of the coil pipe is used as a judgment condition similar to the weight of the accumulated running time of the compressor, and the technical problem that defrosting is started later only by the accumulated running time of the compressor under certain working conditions is solved.

The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention, are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention without limiting the invention to the right. It is obvious that the drawings in the following description are only some embodiments, and that for a person skilled in the art, other drawings can be derived from them without inventive effort. In the drawings:

FIG. 1 is a schematic flow chart of the method of example 1 of the present invention;

FIG. 2 is a schematic flow chart of the method of embodiment 2 of the present invention.

It should be noted that the drawings and the description are not intended to limit the scope of the inventive concept in any way, but to illustrate it by a person skilled in the art with reference to specific embodiments.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and the following embodiments are used for illustrating the present invention and are not intended to limit the scope of the present invention.

In the description of the present invention, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

As shown in fig. 1-2, the invention provides a defrosting control method for a heat pump water heater, wherein the control method further determines the accumulated operation time of a compressor and/or the temperature reduction amplitude of a coil after the environmental temperature, the temperature of the coil and the start operation time of the compressor reach preset values, so that the accumulated operation time of the compressor and/or the temperature reduction amplitude of the coil reach the preset values to serve as judgment conditions for starting defrosting. On the basis of the prior art, the defrosting control method further determines the accumulated running time of the compressors under different working conditions according to the temperature of the water tank and the ambient temperature, and can determine whether to start defrosting according to the amplitude of the temperature drop of the coil pipe.

According to the control method, on the basis that the environmental temperature, the coil temperature and the running time of the compressor are taken as the basis for judging whether defrosting is started in the prior art, the accumulated running time of the compressor under different working conditions is obtained through calculation of the water tank temperature and the environmental temperature, the calculation mode and the change rule of the accumulated running time of the compressor are provided, a design scheme which is suitable for different environments is provided for a defrosting control scheme of a heat pump water heater, and the application prospect of the defrosting control scheme is expanded.

In addition, the temperature reduction amplitude of the coil in the defrosting control method of the heat pump water heater provided by the invention is used as a judgment condition similar to the weight of the accumulated running time of the compressor, so that the technical problem that the defrosting is started late only by the accumulated running time of the compressor under certain working conditions is solved.

Example 1

In this embodiment, as shown in fig. 1, a defrosting control method for a heat pump water heater is provided, where after an ambient temperature, a coil temperature, and a compressor start-up operation time all reach preset values, the control method further determines an accumulated operation time of the compressor and/or a coil temperature reduction amplitude, and the accumulated operation time of the compressor and/or the coil temperature reduction amplitude reach the preset values to serve as a judgment condition for defrosting start-up.

In the embodiment, the water heater in the prior art adopts fixed environment temperature, coil temperature and compressor running time as defrosting starting conditions, and if the temperature of the water tank is high, defrosting can be started in advance under the condition that a frosting layer of an evaporator does not reach the condition of hindering heat transfer; it is also possible that in the case of low ambient temperature and low tank temperature, a thicker frost layer is formed on the evaporator surface, but the frost formation procedure is not initiated due to insufficient compressor run time. The invention comprehensively considers the factors, and takes the accumulated running time of the compressor and the temperature reduction amplitude of the coil as newly-added judgment conditions on the basis of the prior art, so that the defrosting starting time is more refined. The environment temperature is the outdoor environment temperature when the heat pump water heater works, and the coil temperature is the coil temperature of the evaporator.

In this embodiment, the control method starts defrosting when the accumulated operation time of the compressor reaches the preset value and the temperature reduction amplitude of the coil reaches the preset value at the same time, which are used as the judgment conditions for starting defrosting.

In this embodiment, under some working conditions, for example, when the ambient temperature changes greatly or the cooling amplitude at night is large, the accumulated running time of the compressor reaches the preset weight and the temperature reduction amplitude of the coil reaches the preset weight, so that the two are used as the judgment conditions for defrosting start, and defrosting is started when any one of the conditions is reached. The coil temperature reduction amplitude is used as a judgment condition similar to the weight of the accumulated running time of the compressor, and under certain working conditions, for example, when the environment temperature is low and the temperature of the water tank is high, the defrosting starting time is judged later only by the accumulated running time of the compressor, and at the moment, the coil temperature reduction amplitude can be used as a condition which is achieved first, so that the system is promoted to start defrosting.

In this embodiment, the accumulated running time of the compressor is obtained by looking up a table and performing logical operation on the condition of the ambient temperature and the temperature of the water tank acquired by the heat pump water heater.

In this embodiment, the table lookup includes: and obtaining an approximate compressor running time range according to the water tank temperature and the outdoor environment temperature obtained by the heat pump water heater and a table according to the running working conditions of the heat pump water heater under the conditions. The logical operation comprises: and setting different coefficients for the current water tank temperature and the outdoor environment temperature to perform weighting operation, and adding the starting operation time of the compressor to obtain the accumulated operation time of the compressor.

In the embodiment, under the same environmental temperature, the accumulated running time of the compressor is increased along with the temperature rise of the water tank; under the same water tank temperature, the accumulated running time of the compressor tends to increase firstly and then decrease along with the decrease of the ambient temperature.

In this embodiment, the temperature of the water tank includes a low temperature threshold, a medium temperature threshold and a high temperature threshold, the temperature of the environment includes a first threshold, a second threshold and a third threshold, the temperature of the environment gradually decreases, and the accumulated operation time of the compressor is longest when the temperature of the environment is at the second threshold and the temperature of the water tank is at the high temperature threshold; and when the temperature of the water tank is not changed, the accumulated running time of the compressor when the ambient temperature is in the first threshold condition is not greater than the accumulated running time of the compressor when the ambient temperature is in the third threshold condition.

In the embodiment, the variation trends of the accumulated running time of the compressor, which are influenced by the temperature of the water tank and the ambient temperature, are different, and the accumulated running time of the compressor is increased along with the increase of the temperature of the water tank under the same ambient temperature; under the same water tank temperature, the accumulated running time of the compressor tends to increase firstly and then decrease along with the decrease of the ambient temperature. As shown in the following table:

the accumulated running times a3, a6 and a9 corresponding to the high temperature threshold of the water tank temperature are respectively greater than the accumulated running times corresponding to the low temperature threshold and the medium temperature threshold in the same row on the left side of the table; and when the ambient temperature is at the second threshold, the accumulated running time of the corresponding compressor is longer, so that the accumulated running times of a4, a5 and a6 are respectively larger than the accumulated running times of the first threshold and the second threshold which are in the same column at the upper side and the lower side of the table. The accumulated running time of the compressor determined by the invention is influenced by the temperature of the water tank and the ambient temperature to have certain difference, for example, when the temperature of the water tank is at a high temperature threshold and the ambient temperature is at a second threshold, the time length of the accumulated running time a6 of the compressor is obtained by table lookup and calculation and is greater than the time length of a4, because the temperature of the water tank corresponding to a6 represents the process that the compressor is increased from low to high under the accumulation work, a6 is closer to the preset accumulated running time of the compressor, and at the moment, the frost formation amount is small because the temperature of the water tank is higher; however, if the heat pump water heater is operated at a lower water tank temperature, the obtained accumulated operation time of the compressor is a4, although a4 has a certain time compared with a6 from the preset accumulated operation time of the compressor, the accumulated operation time of the compressor at a lower water temperature is actually included in a6 and is larger in occupation, so that the accumulated operation time of the compressor at a lower water tank temperature of the heat pump water heater can reach the preset accumulated operation time of the compressor more quickly, and defrosting is started to remove a large amount of frost generated due to the lower water temperature. To illustrate the above process more clearly, in this example, it is assumed that the accumulated operation time corresponding to a6 is 24min, the water tank temperature reaching the high temperature threshold actually rises from the low temperature threshold and the medium temperature threshold, and the compressor operation time is longer at the low temperature threshold, so the accumulated operation time corresponding to a4 is 20min, the accumulated operation time corresponding to a5 is 22min, which includes 20min of the accumulated operation time corresponding to a4 at the low temperature threshold, and if the preset compressor accumulated operation time is 26min, the difference between a4 of the low water tank temperature and a6 of the high water tank temperature reaching the preset compressor accumulated operation time 26min is not large, which can timely clear up a large amount of frost generated by the low water tank temperature operation. In contrast, in the prior art, a fixed defrosting interval is always used as a judgment basis for starting defrosting, in this case, if the water temperature in the water tank is always at a lower level, the frosting amount is large, and the defrosting effect may be poor when the fixed defrosting interval is reached, and if the water temperature in the water tank is always at a higher level, the frosting amount is small, and at this time, the defrosting operation is started when the fixed defrosting interval is reached, so that the consumed energy is large. The prior art does not consider the influence of the temperature of the water tank and the ambient temperature, and the condition that defrosting is started in advance or defrosting is not uniform can be generated.

In this embodiment, the compressor starting operation time is an operation time of the compressor after the heat pump water heater is started, and the accumulated operation time of the compressor includes the compressor starting operation time.

In this embodiment, after the heat pump water heater is started to operate for a period of time, the ambient temperature and the coil temperature are obtained and whether defrosting is started or not is judged, so that the preset compressor starting operation time needs to be used as an initial node, and the method of the invention starts to perform advanced judgment from the initial node, so that the subsequently calculated accumulated compressor operation time also includes the compressor starting operation time.

In this embodiment, the accumulated operating time of the compressor is recalculated after each defrosting operation is completed.

In this embodiment, since the compressor may intermittently operate under some operating conditions, the accumulated operating time of the compressor and the preset accumulated operating time of the compressor are not equal to the defrosting interval.

In this embodiment, the coil temperature decrease amplitude is a decrease amplitude of the coil temperature in a unit time, and the unit time is calculated from a time point when the ambient temperature, the coil temperature, and the compressor start-up operation time all reach preset values.

In the embodiment, besides the accumulated running time of the compressor, the temperature reduction amplitude of the coil pipe is introduced as a judgment condition so as to deal with the condition that defrosting is started late only by the accumulated running time of the compressor under certain working conditions; the unit time is the same as the accumulated running time of the preset compressor under certain working conditions.

In this embodiment, the control method further includes taking that the temperature of the coil or the defrosting operation time reaches a preset value as a judgment condition for defrosting completion. When either of the two conditions is achieved, the defrosting operation is finished.

In this embodiment, the defrosting control method specifically includes:

s1, acquiring the temperature of an evaporator coil and the temperature of an outdoor environment after the starting running time of a compressor reaches a preset value, and then executing a step S2;

s2, when the temperature of the evaporator coil and the outdoor environment temperature are not greater than the preset value, starting a timer, and then executing the step S3;

s3, during the running of the timer, obtaining the accumulated running time of the compressor through table look-up and logic operation according to the obtained water tank temperature and the obtained environment temperature, simultaneously obtaining the amplitude reduction of the coil temperature in unit time of the timer in real time, and then executing the step S4;

s4, in the same time period, the system judges whether the accumulated running time of the compressor reaches the preset value firstly or the temperature reduction amplitude of the coil pipe reaches the preset value firstly, when any judgment result occurs firstly, the defrosting action is started, and then the step S5 is executed;

and S5, in the defrosting process, when the temperature of the coil detected by the heat pump water heater rises to a preset value or the defrosting operation time reaches a preset value, finishing the defrosting action.

Example 2

In this embodiment, based on embodiment 1, as shown in fig. 2, the judgment condition for defrosting start is adjusted, and the difference from embodiment 1 is that:

in this embodiment, the control method uses the condition that the accumulated operation time of the compressor reaches the preset value and the temperature decrease amplitude of the coil reaches the preset value as the judgment condition for starting the defrosting, and starts the defrosting when the system detects that the accumulated operation time of the compressor reaches the preset value.

In this embodiment, under some conditions, for example, when the temperature of the water tank is high, the frost formation amount of the evaporator is small, and it is only necessary to determine whether the accumulated running time of the compressor is reached as the basis for starting defrosting.

In this embodiment, the defrosting control method specifically includes:

s1, acquiring the temperature of an evaporator coil and the temperature of an outdoor environment after the starting running time of a compressor reaches a preset value, and then executing a step S2;

s2, when the temperature of the evaporator coil and the outdoor environment temperature are not greater than the preset value, starting a timer, and then executing the step S3;

s3, during the running of the timer, obtaining the accumulated running time of the compressor through table look-up and logic operation according to the obtained water tank temperature and the obtained environment temperature, simultaneously obtaining the amplitude reduction of the coil temperature in unit time of the timer in real time, and then executing the step S4;

s4, the system judges that when the accumulated running time of the compressor of the heat pump water heater reaches the preset value, the defrosting action is started, and then the step S5 is executed;

and S5, in the defrosting process, when the temperature of the coil detected by the heat pump water heater rises to a preset value or the defrosting operation time reaches a preset value, finishing the defrosting action.

Other embodiments of this example are the same as example 1.

Example 3

This embodiment provides a heat pump water heater, heat pump water heater is air source heat pump water heater, includes: a memory storing an executable program and a processor executing the executable program to implement the defrosting control method of the heat pump water heater according to embodiment 1 or 2.

Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.