Control method of heat pump water system

Abstract

The invention relates to a heat pump water system, in particular to a control method of the heat pump water system, and aims to solve the problem that the energy efficiency of the system cannot be ensured while stable output of hot water is ensured in the conventional heat pump water system. In order to achieve the purpose, the heat pump water system comprises a water tank, an air source heat pump unit, an auxiliary heating device, a first temperature sensor and a second temperature sensor. The air source heat pump unit and the auxiliary heating device are used for providing heat for the water tank, the first temperature sensor is used for detecting first water temperature, and the second temperature sensor is used for detecting second water temperature of the water tank at the position different from that of the first temperature sensor. The control method comprises the steps that when the heat pump unit is in a heating mode, a first temperature, a first water temperature, a second water temperature and an outdoor environment temperature are obtained; calculating a first temperature difference value between the first water temperature and the second water temperature and a second temperature difference value between the set water temperature and the first water temperature; based on the first temperature difference value, the second temperature difference value and the outdoor environment temperature, starting and stopping of the auxiliary heating device are controlled.

Description

Technical Field

[0001] The present invention relates to the field of heat pump water systems, and in particular provides a control method for a heat pump water system. Background Art

[0002] Air source heat pump water systems are gaining increasing attention as an efficient and environmentally friendly way to provide hot water. Compared with traditional hot water heating methods, air source heat pump water systems offer significant energy savings and are environmentally friendly.

[0003] However, air-source heat pump water systems often face slow heating speeds in practical applications. To address this, auxiliary heating devices (such as electric or gas heaters) are introduced to provide additional heat. However, current control strategies for air-source heat pump water systems cannot adequately address changes in ambient temperature and fluctuations in water demand, and are unable to simultaneously ensure stable hot water output and improve overall system energy efficiency.

[0004] Accordingly, the art requires a new control method for a heat pump water system to solve the problem that the existing heat pump water system cannot ensure stable hot water output while also ensuring system energy efficiency. Summary of the Invention

[0005] The present invention aims to solve the above technical problem, that is, to solve the problem that the existing heat pump water system cannot ensure the stable output of hot water while also ensuring the energy efficiency of the system.

[0006] In a first aspect, the present invention provides a control method for a heat pump water system, characterized in that the heat pump water system includes: a water tank; an air source heat pump unit, used to directly or indirectly provide heat to the water tank in a heating mode; an auxiliary heating device, used to provide heat to the water tank in an on state; a first temperature sensor, used to detect a first water temperature of the water tank; a second temperature sensor, used to detect a second water temperature of the water tank at a position different from the first temperature sensor; an ambient temperature sensor, used to detect the outdoor ambient temperature; the control method includes: when the heat pump unit is in a heating mode, obtaining the first water temperature, the second water temperature and the outdoor ambient temperature; calculating a first temperature difference between the first water temperature and the second water temperature and a second temperature difference between the set water temperature and the first water temperature; and controlling the opening and closing of the auxiliary heating device based on the first temperature difference, the second temperature difference and the outdoor ambient temperature.

[0007] When the demand for water is high, a large amount of hot water in the water tank will be used in a short period of time, resulting in a lower water temperature in the water tank. After the hot water is used, cold water is replenished into the water tank, and uneven temperature distribution in the water tank may occur. The first temperature difference value of the present invention can reflect whether the hot water has stratification or uneven temperature, the second temperature difference value can reflect the high and low water temperature in the water tank, and the outdoor ambient temperature can reflect the heating efficiency of the heat pump. The auxiliary heating device can heat the water tank evenly when needed to avoid local overcooling, ensure the uniformity and rapid temperature reaching of the water temperature in the entire water tank, and control the opening and closing of the auxiliary heating device in combination with the heating efficiency of the heat pump, and optimize energy efficiency and save energy. Therefore, combining the above three to reasonably control the opening and closing of the auxiliary heating device can ensure that the water temperature in the water tank reaches the temperature quickly, maintain the stability of the hot water supply, and at the same time maximize the overall energy efficiency of the system and reduce unnecessary energy consumption.

[0008] In an optional technical solution of the control method of the above-mentioned heat pump water system, the first temperature sensor is arranged at the upper part of the water tank, and the second temperature sensor is arranged at the lower part of the water tank; a heating structure is provided at the lower part of the water tank, and the auxiliary heating device includes a first heating element and a second heating element, the first heating element is used to heat the heating structure or the first heating element is constituted as the heating structure, and the second heating element is used to heat the water tank as a whole; the step of "controlling the opening and closing of the auxiliary heating device based on the first temperature difference value, the second temperature difference value and the outdoor ambient temperature" further includes: controlling the opening and closing of the first heating element and the second heating element based on the first temperature difference value, the second temperature difference value and the outdoor ambient temperature.

[0009] Large temperature differences within the water tank are primarily manifested in uneven temperature distribution between the upper and lower parts of the tank, with higher temperatures in the upper part and lower parts. Therefore, the first heating element is primarily responsible for heating the cold water area in the lower part of the tank to prevent uneven temperature distribution within the tank; the second heating element is responsible for heating the entire tank to ensure that the overall temperature within the tank reaches the desired level. Therefore, by monitoring the first and second temperature differences and the outdoor ambient temperature, the system activates and deactivates the first and second heating elements based on actual demand and environmental changes, ensuring efficient and stable output of hot water from the tank while also controlling system energy consumption.

[0010] In the optional technical solution of the control method of the above-mentioned heat pump water system, the step of "controlling the opening and closing of the first heating element and the second heating element based on the outdoor ambient temperature, the first temperature difference value and the second temperature difference value" further includes: comparing the first temperature difference value with the first preset temperature value; comparing the second temperature difference value with the second preset temperature value; comparing the outdoor ambient temperature with the third preset temperature value; and controlling the opening and closing of the first heating element and the second heating element based on the comparison result.

[0011] By introducing a comparison between the first, second, and third preset temperature values, more precise heating regulation can be achieved. This can better adapt to different seasons and usage scenarios, avoid overheating or underheating, and ensure the stability of hot water supply while effectively saving energy.

[0012] In the optional technical solution of the control method of the above-mentioned heat pump water system, the step of "controlling the opening and closing of the first heating element and the second heating element based on the comparison result" further includes: when the first temperature difference value is less than the first preset temperature value, controlling the first heating element to be closed; based on the comparison result between the second temperature difference value and the second preset temperature value, and the comparison result between the outdoor ambient temperature and the third preset temperature value, controlling the opening and closing of the second heating element.

[0013] When the first temperature difference is less than the first preset temperature value, it proves that the water temperature difference between the upper and lower parts of the water tank is not large, and the heat distribution is relatively uniform. Therefore, the first heating element can be turned off to avoid overheating and unnecessary energy waste. In this case, the water temperature of the water tank and the heating efficiency of the air source heat pump unit are judged by comparing the second temperature difference with the second preset temperature value, and the outdoor ambient temperature with the third preset temperature value. Combining these two situations, it is determined whether the second heating element used to increase the overall water temperature of the water tank needs to be turned on, so as to optimize energy utilization and ensure the overall energy efficiency of the system while ensuring that the water temperature in the water tank reaches the temperature.

[0014] In the optional technical solution of the control method of the above-mentioned heat pump water system, the step of "controlling the second heating element to be turned on and off based on the comparison result of the second temperature difference value and the second preset temperature value, and the comparison result of the outdoor ambient temperature and the third preset temperature value" further includes: when the second temperature difference value is less than the second preset temperature value, if the outdoor ambient temperature is less than the third preset temperature value, the second heating element is controlled to be turned on; if the outdoor ambient temperature is greater than or equal to the third preset temperature value, the second heating element is controlled to be turned off; and / or when the second temperature difference value is greater than or equal to the second preset temperature value, the second heating element is controlled to be turned on.

[0015] When the second temperature difference is less than the second preset temperature value, but the outdoor ambient temperature is less than the third preset temperature value, it proves that although the water temperature in the water tank has reached the target temperature, the heating efficiency of the air source heat pump unit is low. Due to the insufficient heating capacity of the air source heat pump unit, the water temperature in the water tank may decrease. In order to avoid the temperature fluctuations that may be caused, the second heating element is controlled to be turned on to compensate for the impact of the low heating efficiency of the heat pump. When the second temperature difference is less than the second preset temperature value and the outdoor ambient temperature is greater than or equal to the third preset temperature value, it proves that the water temperature in the water tank has reached the target temperature and the heating efficiency of the air source heat pump unit is also high. In order to avoid energy waste, the second heating element is controlled to be turned off in this case. When the second temperature difference is greater than or equal to the second preset temperature value, it proves that the water temperature in the water tank is low and has not reached the expected target temperature. In this case, regardless of the heating efficiency of the air source heat pump unit, the second heating element is controlled to be turned on so that the overall water temperature in the water tank reaches the target temperature as soon as possible to ensure a stable and continuous supply of hot water.

[0016] In the optional technical solution of the control method of the above-mentioned heat pump water system, the step of "controlling the opening and closing of the first heating element and the second heating element based on the comparison result" further includes: when the first temperature difference value is greater than or equal to the first preset temperature value, if the second temperature difference value is greater than or equal to the second preset temperature value, controlling the first heating element to turn on; based on the comparison result between the outdoor ambient temperature and the third preset temperature value, controlling the opening and closing of the second heating element.

[0017] When the first temperature difference is greater than or equal to the first preset temperature value, and the second temperature difference is greater than or equal to the second preset temperature value, it indicates that the water temperature difference between the upper and lower parts of the water tank is large, and the water temperature inside the water tank is also low. Therefore, it is necessary to turn on the first heating element to reduce the temperature difference of the water in the water tank and avoid unstable water temperature caused by local overheating or overcooling. In order to increase the water temperature in the water tank while taking energy conservation into account, it is necessary to consider the heating efficiency of the air source heat pump unit to determine whether to turn on the second heating element.

[0018] In the optional technical solution of the control method of the above-mentioned heat pump water system, the step of "controlling the opening and closing of the second heating element based on the comparison result between the outdoor ambient temperature and the third preset temperature value" further includes: if the outdoor ambient temperature is lower than the third preset temperature value, the second heating element is controlled to be turned on; if the outdoor ambient temperature is greater than or equal to the third preset temperature value, the second heating element is controlled to be turned off.

[0019] When the outdoor ambient temperature is lower than the third preset temperature value, the heating efficiency of the air source heat pump unit is usually poor and cannot effectively increase the water tank temperature. Therefore, turning on the second heating element can effectively supplement heat, increase the overall temperature of the water tank, ensure that the water temperature meets the standard, and avoid insufficient heating of the system due to the outdoor temperature being too low. When the outdoor ambient temperature is greater than or equal to the third preset temperature value, the heating efficiency of the air source heat pump unit is better and can fully utilize the external heat to heat the water tank, so there is no need to turn on the second heating element. Turning off the second heating element can avoid unnecessary energy waste and improve the overall energy efficiency of the system.

[0020] In the optional technical solution of the control method of the above-mentioned heat pump water system, the step of "controlling the opening and closing of the first heating element and the second heating element based on the comparison result" further includes: when the first temperature difference value is greater than or equal to the first preset temperature value, if the second temperature difference value is less than the second preset temperature value, controlling the second heating element to be closed; based on the comparison result between the outdoor ambient temperature and the third preset temperature value, controlling the opening and closing of the first heating element.

[0021] When the first temperature difference is greater than or equal to the first preset temperature value, and the second temperature difference is less than the second preset temperature value, it indicates that the water temperature difference between the upper and lower parts of the water tank is large, but the water temperature in the water tank has reached the desired temperature. Since the water temperature in the water tank has reached the desired temperature, the second heating element that controls the heating of the entire water tank is turned off to avoid overheating and unnecessary energy waste. Since the air source heat pump unit can also heat the water in the lower part of the water tank, the heating efficiency of the air source heat pump unit is judged by comparing the outdoor ambient temperature with the third preset temperature value, and based on this, it is determined whether to turn on the first heating element in the lower part of the water tank. This can avoid a large difference in water temperature between the upper and lower parts of the water tank while also taking into account the optimal use of energy.

[0022] In the optional technical solution of the control method of the above-mentioned heat pump water system, the step of "controlling the opening and closing of the first heating element based on the comparison result between the outdoor ambient temperature and the third preset temperature value" further includes: if the outdoor ambient temperature is lower than the third preset temperature value, the first heating element is controlled to be turned on; if the outdoor ambient temperature is greater than or equal to the third preset temperature value, the first heating element is controlled to be turned off.

[0023] When the outdoor ambient temperature is less than the third preset temperature value, the air-source heat pump unit's heating efficiency is generally poor, failing to effectively heat the water in the lower portion of the water tank. The effect of reducing the local temperature difference in the water within the water tank is not significant. Therefore, controlling the first heating element to turn on can compensate for the air-source heat pump unit's insufficient heating efficiency and ensure a stable and continuous supply of hot water. When the outdoor ambient temperature is greater than or equal to the third preset temperature value, the air-source heat pump unit's heating efficiency is high, fully heating the water in the lower portion of the water tank. Therefore, controlling the first heating element to turn off can avoid unnecessary energy waste and improve the system's overall energy efficiency.

[0024] In an optional technical solution of the control method of the above-mentioned heat pump water system, the second heating element is arranged in the middle of the water tank; and / or the heat pump water system also includes a heat exchange path structure, the heat exchange path structure is configured to be able to exchange heat with the heat exchanger of the air source heat pump unit, the heating structure is configured as a heat exchange coil, the heat exchange coil is connected to the heat exchange path structure, the first heating element is configured as an electric heating box, and the electric heating box is connected to the pipeline between the heat exchange path structure and the heat exchange coil. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The preferred embodiments of the present invention are described below with reference to the accompanying drawings, in which:

[0026] Figure 1 2. It is a structural diagram of the air source heat pump unit of the heat pump water system of the present invention;

[0027] Figure 2 It is a structural schematic diagram of the water tank of the heat pump water system of the present invention;

[0028] Figure 3 This is a main flow chart of the control method of the heat pump water system of the present invention;

[0029] Figure 4 It is a possible logic diagram of the control method of the heat pump water system of the present invention.

[0030] Description of reference numerals:

[0031] 1-water tank; 11-water inlet pipe; 12-water outlet pipe; 2-air source heat pump unit; 21-compressor; 22-first heat exchanger; 23-throttling element; 24-second heat exchanger; 3-first heating element; 4-second heating element; 5-first temperature sensor; 6-second temperature sensor; 7-heat exchange path structure; 8-heat exchange coil. DETAILED DESCRIPTION

[0032] Preferred embodiments of the present invention are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely intended to illustrate the technical principles of the present invention and are not intended to limit the scope of protection of the present invention. Those skilled in the art may adjust these embodiments as needed to suit specific applications.

[0033] It should be noted that, in the description of the present invention, the terms "upper" and "lower" refer to the upper and lower parts of the heat pump water system in the use state based on the height direction. In addition, it should be noted that, in the description of the present invention, unless otherwise clearly stipulated and limited, the terms "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances. In addition, the terms "first", "second" and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0034] The present invention provides a control method for a heat pump water system. Figure 1 and Figure 2 As shown, the heat pump water system includes a water tank 1, an air source heat pump unit 2, an auxiliary heating device, a first temperature sensor 5, a second temperature sensor 6, and an ambient temperature sensor. The air source heat pump unit 2 is used to directly or indirectly provide heat to the water tank 1 in heating mode. The auxiliary heating device is used to provide heat to the water tank 1 when it is turned on. The first temperature sensor 5 is used to detect a first water temperature in the water tank 1. The second temperature sensor 6 is used to detect a second water temperature in the water tank 1 at a different location from the first temperature sensor 5. The ambient temperature sensor is used to detect the outdoor ambient temperature. The first temperature sensor 5 and the second temperature sensor 6 are arranged at different locations in the water tank 1. For example, the first temperature sensor 5 is arranged at the upper part of the water tank 1 so that the first temperature sensor 5 detects the first water temperature in the upper part of the water tank 1; the second temperature sensor 6 is arranged at the lower part of the water tank 1 so that the second temperature sensor 6 detects the second water temperature in the lower part of the water tank 1.

[0035] It is understandable that the air source heat pump unit 2 includes a compressor 21, a first heat exchanger 22, a throttling element 23 (such as an electronic expansion valve or a capillary tube, etc.), and a second heat exchanger 24, which are connected in sequence to form a closed loop. The second heat exchanger 24 absorbs heat from the outdoor environment to evaporate the refrigerant and convert it from a liquid into a low-temperature, low-pressure gas. The compressor 21 then compresses these gases to form a high-temperature, high-pressure gas. The high-temperature, high-pressure gas refrigerant is sent to the first heat exchanger 22. The hot gas refrigerant transfers its heat directly or indirectly to the water tank 1, causing the refrigerant to cool and condense into a liquid. The condensed high-pressure liquid refrigerant is decompressed through the expansion valve and quickly becomes a low-temperature, low-pressure liquid. It is then sent back to the second heat exchanger 24 to restart the cycle. Among them, the ambient temperature sensor is set on the outdoor side, for example, on the outdoor casing equipped with the second heat exchanger 24 or directly placed outdoors.

[0036] When the first heat exchanger 22 directly provides heat to the water tank 1, the first heat exchanger 22 can constitute a coil or other heat exchange structure, etc., which can be arranged in the lower part or other position of the water tank 1, or wrapped around the outer wall of the water tank 1, etc. When the first heat exchanger 22 indirectly provides heat to the water tank 1, the heat pump water system can also include a heat exchange path structure 7 and a heat exchange coil 8. The heat exchange path structure 7 is connected to the heat exchange coil 8 to form a closed loop. The heat exchange coil 8 is arranged in the lower part of the water tank 1, or wrapped around the outer wall of the lower part of the water tank 1. The heat exchange path structure 7 is configured to be able to exchange heat with the first heat exchanger 22, so as to transfer the heat emitted by the first heat exchanger 22 to the water in the water tank 1 through the heat exchange path structure 7 and the heat exchange coil 8 in sequence. Among them, the specific forms in which the heat exchange path structure 7 is configured to be able to exchange heat with the first heat exchanger 22 include various forms. For example, the heat exchange path structure 7 and the first heat exchanger 22 together constitute a shell and tube heat exchange structure, a plate heat exchanger or a spiral coil heat exchanger, etc. As long as the heat exchange path structure 7 can exchange heat with the first heat exchanger 22, the adjustment of its specific form does not deviate from the principle of the present invention and is within the scope of protection of the present invention. In addition, it should be noted that the implementation method of the first heat exchanger 22 indirectly providing heat to the water tank 1 is not limited to the one described above. For example, the heat pump water system may include a heat exchange refrigerant pipe, the first heat exchanger 22 and the heat exchange refrigerant pipe form a closed loop, and the heat exchange refrigerant pipe is arranged in the water tank 1, etc.

[0037] As one possible embodiment, the auxiliary heating device includes a first heating element 3 and a second heating element 4. The first heating element 3 can be configured as an electric heating enclosure. It is understood that the electric heating enclosure includes a cavity and an electric heating element (such as a heating wire or heating rod, etc.) mounted therein. The cavity is connected to the pipeline between the aforementioned heat exchange path structure 7 and the heat exchange coil 8. A circulation pump can be installed in this pipeline to promote liquid circulation in the circuit. When the first heating element 3 is turned on, it heats the liquid in the cavity. The heated liquid then flows into the heat exchange coil 8, thereby heating the water in the lower portion of the water tank 1. Alternatively, the first heating element 3 can be configured as a heating rod that can be directly inserted into the lower side wall of the water tank 1; or the first heating element 3 can be configured as a heating wire that can be wrapped around the lower side wall of the water tank 1. The second heating element 4 can heat the entire water tank 1. For example, the second heating element 4 can be located in the middle of the water tank 1 so that when the second heating element 4 is turned on, it can heat the water in both the upper and lower portions of the water tank 1. Specifically, the second heating element 4 can be configured as a heating rod and arranged in the middle of the water tank 1; or the second heating element 4 can be configured as a heating wire, which is wound around the middle of the water tank 1. It should be noted that the second heating element 4 is not limited to being arranged in the middle of the water tank 1. As long as it can heat the water tank 1 as a whole, its arrangement can be adjusted. For example, the second heating element 4 is configured as a heating wire, which is wound around the upper and lower parts of the outer wall of the water tank 1 at the same time. These adjustments do not deviate from the principles of the present invention and are within the scope of protection of the present invention. Possibly, the heat pump water system also includes an inlet pipe 11 and an outlet pipe 12, the inlet pipe 11 is connected to the bottom of the water tank 1, and the outlet pipe 12 is connected to the upper part of the water tank 1.

[0038] like Figure 3 As shown, the control method of the heat pump water system of the present invention includes the following steps:

[0039] Step S100: When the air source heat pump unit is in a heating mode, a first water temperature, a second water temperature and an outdoor ambient temperature are obtained.

[0040] When the air source heat pump unit is in heating mode, the first heat exchanger releases heat and transfers the heat to the water in the water tank.

[0041] Step S200: Calculating a first temperature difference between the first water temperature and the second water temperature and a second temperature difference between the set water temperature and the first water temperature.

[0042] It is understood that the set water temperature refers to a set target water temperature. For example, a heat pump water system may include an adjustment panel with a digital display on which a user can enter the desired set water temperature. Alternatively, the heat pump water system controller may be connected to a user's mobile phone or other terminal, allowing the user to set the water temperature via a mobile phone application or web interface.

[0043] Step S300: Based on the first temperature difference value, the second temperature difference value and the outdoor ambient temperature, the auxiliary heating device is controlled to be turned on and off.

[0044] Possibly, step S300 further includes:

[0045] Step S301: comparing a first temperature difference value with a first preset temperature value.

[0046] Step S302: comparing the second temperature difference value with a second preset temperature value.

[0047] Step S303: comparing the outdoor ambient temperature with a third preset temperature value.

[0048] Step S304: Based on the comparison result, controlling the on and off of the first heating element and the second heating element.

[0049] In step S301, the first temperature difference represents the difference in water temperature between the upper and lower parts of the water tank, indicating whether the heat distribution within the water tank is uniform. For example, it indicates the stratification of hot and cold water within the water tank. The first preset temperature value is an indicator of the temperature difference within the water tank. When the first temperature difference is greater than or equal to the first preset temperature value, it indicates that the local temperature difference in the water tank is large. When the first temperature difference is less than the first preset temperature value, it indicates that the local temperature difference in the water tank is small and the hot water distribution is relatively uniform. The first preset temperature value can be adjusted according to actual application to meet different usage requirements. It can be 3°C, 5°C, etc. This embodiment does not impose any specific restrictions on the value of the first preset temperature value.

[0050] In step S302, the second temperature difference represents the difference between the set water temperature and the water tank temperature. The second preset temperature value is an indicator of the water temperature inside the water tank. When the second temperature difference is greater than or equal to the second preset temperature value, the water tank temperature is low. When the second temperature difference is less than the second preset temperature value, the water tank temperature is warm. The second preset temperature value can be adjusted to meet different application requirements and can be 15°C or 10°C. This embodiment does not impose any specific restrictions on the value of the first preset temperature value.

[0051] In step S303, the outdoor ambient temperature has a direct impact on the operating efficiency of the air-source heat pump unit. The third preset temperature value represents an indicator of whether the air-source heat pump unit has entered a low-efficiency mode. When the outdoor ambient temperature is greater than or equal to the third preset temperature value, the air-source heat pump unit's heating efficiency is high. When the outdoor ambient temperature is less than the third preset temperature value, the air-source heat pump unit's heating efficiency is low. The third preset temperature value is typically 0°C, but this value can be adjusted based on regional climate conditions and specific system design requirements. For example, in warm climates (such as southern or subtropical regions), winter outdoor ambient temperatures typically remain high and may not experience extremely low temperatures. Therefore, the third preset temperature value can be set to 5°C or 10°C. That is, when the outdoor ambient temperature falls below this value, the system deems the heat pump unit's heating efficiency to have decreased. In cold climates (such as northern or extremely cold regions), winter temperatures are lower, often falling below 0°C, or even reaching -10°C or lower. In such cases, the system design may allow for the use of lower preset temperature values, such as -5°C or -10°C, to accommodate local climate conditions.

[0052] When the demand for water is high, a large amount of hot water in the water tank will be used in a short period of time, resulting in a lower water temperature in the water tank. After the hot water is used, cold water is replenished into the water tank, which may cause uneven temperature distribution in the water tank. Or the water temperature in the water tank is unevenly distributed due to the natural convection principle of hot water rising and cold water sinking. By comparing the first temperature difference value, the second temperature difference value, the outdoor ambient temperature and the corresponding preset temperature values (the first preset temperature difference value, the second preset temperature difference value, and the third preset temperature value), it is possible to comprehensively judge the local temperature difference of the water in the water tank, the high and low water temperature in the water tank, and the heating efficiency of the air source heat pump unit. Combining the above three situations to comprehensively control the opening and closing of the auxiliary heating device, the water tank can be evenly heated when needed to avoid local overcooling, ensure the uniformity of the water temperature in the entire water tank and rapid temperature reaching, and optimize energy efficiency and save energy.

[0053] In step S304, the following three implementations may be included. It should be noted that the following three implementations may be combined into a whole solution, or may be combined into a solution in pairs, or may be independent solutions.

[0054] In a first embodiment, when the first temperature difference is less than a first preset temperature value, the first heating element is controlled to be turned off. Based on a comparison between the second temperature difference and the second preset temperature value, and a comparison between the outdoor ambient temperature and a third preset temperature value, the second heating element is controlled to be turned on and off.

[0055] When the first temperature difference is less than the first preset temperature value, it proves that the water temperature difference between the upper and lower parts of the water tank is not large, and the heat distribution is relatively uniform. Therefore, the first heating element can be turned off to avoid overheating and unnecessary energy waste. In this case, the water temperature of the water tank and the heating efficiency of the air source heat pump unit are judged by comparing the second temperature difference with the second preset temperature value, and the outdoor ambient temperature with the third preset temperature value. Combining these two situations, it is determined whether the second heating element used to increase the overall water temperature of the water tank needs to be turned on, so as to optimize energy utilization and ensure the overall energy efficiency of the system while ensuring that the water temperature in the water tank reaches the temperature.

[0056] Furthermore, when the second temperature difference is less than the second preset temperature value, if the outdoor ambient temperature is less than the third preset temperature value, the second heating element is controlled to be turned on; if the outdoor ambient temperature is greater than or equal to the third preset temperature value, the second heating element is controlled to be turned off. When the second temperature difference is less than the second preset temperature value, but the outdoor ambient temperature is less than the third preset temperature value, it proves that although the water temperature in the water tank has reached the temperature, the heating efficiency of the air source heat pump unit is low. Due to the insufficient heating capacity of the air source heat pump unit, the water temperature in the water tank may decrease. In order to avoid the possible temperature fluctuations, the second heating element is controlled to be turned on to compensate for the impact of the low heating efficiency of the heat pump. When the second temperature difference is less than the second preset temperature value and the outdoor ambient temperature is greater than or equal to the third preset temperature value, it proves that the water temperature in the water tank has reached the temperature and the heating efficiency of the air source heat pump unit is also high. In order to avoid energy waste, the second heating element is controlled to be turned off in this case. When the second temperature difference is greater than or equal to the second preset temperature value, it proves that the water temperature in the water tank is low and has not reached the expected target temperature. In this case, regardless of the heating efficiency of the air source heat pump unit, the second heating element is controlled to be turned on so that the water temperature of the entire water tank reaches the temperature as quickly as possible to ensure a stable and continuous supply of hot water.

[0057] The second implementation method: when the first temperature difference is greater than or equal to the first preset temperature value, if the second temperature difference is greater than or equal to the second preset temperature value, the first heating element is controlled to turn on; based on the comparison result between the outdoor ambient temperature and the third preset temperature value, the second heating element is controlled to turn on and off.

[0058] When the first temperature difference is greater than or equal to the first preset temperature value, and the second temperature difference is greater than or equal to the second preset temperature value, it indicates that the water temperature difference between the upper and lower parts of the water tank is large, and the water temperature inside the water tank is also low. Therefore, it is necessary to turn on the first heating element to reduce the temperature difference of the water in the water tank and avoid unstable water temperature caused by local overheating or overcooling. In order to increase the water temperature in the water tank while taking energy conservation into account, it is necessary to consider the heating efficiency of the air source heat pump unit to determine whether to turn on the second heating element.

[0059] Possibly, if the outdoor ambient temperature is less than a third preset temperature value, the second heating element is controlled to turn on; if the outdoor ambient temperature is greater than or equal to the third preset temperature value, the second heating element is controlled to turn off. When the outdoor ambient temperature is less than the third preset temperature value, the heating efficiency of the air source heat pump unit is usually poor, and the water tank temperature cannot be effectively increased. Therefore, turning on the second heating element can effectively supplement heat, increase the overall temperature of the water tank, ensure that the water temperature meets the standard, and avoid insufficient heating of the system due to the outdoor temperature being too low. When the outdoor ambient temperature is greater than or equal to the third preset temperature value, the heating efficiency of the air source heat pump unit is better, and the external heat can be fully utilized to heat the water tank, so there is no need to turn on the second heating element. Turning off the second heating element can avoid unnecessary energy waste and improve the overall energy efficiency of the system.

[0060] The third implementation method: when the first temperature difference is greater than or equal to the first preset temperature value, if the second temperature difference is less than the second preset temperature value, the second heating element is controlled to be turned off; based on the comparison result between the outdoor ambient temperature and the third preset temperature value, the first heating element is controlled to be turned on and off.

[0061] When the first temperature difference is greater than or equal to the first preset temperature value, and the second temperature difference is less than the second preset temperature value, it indicates that the water temperature difference between the upper and lower parts of the water tank is large, but the water temperature in the water tank has reached the desired temperature. Since the water temperature in the water tank has reached the desired temperature, the second heating element that controls the heating of the entire water tank is turned off to avoid overheating and unnecessary energy waste. Since the air source heat pump unit can also heat the water in the lower part of the water tank, the heating efficiency of the air source heat pump unit is judged by comparing the outdoor ambient temperature with the third preset temperature value, and based on this, it is determined whether to turn on the first heating element in the lower part of the water tank. This can avoid a large difference in water temperature between the upper and lower parts of the water tank while also taking into account the optimal use of energy.

[0062] Possibly, if the outdoor ambient temperature is less than a third preset temperature value, the first heating element is controlled to be turned on; if the outdoor ambient temperature is greater than or equal to the third preset temperature, the first heating element is controlled to be turned off. When the outdoor ambient temperature is less than the third preset temperature value, the heating efficiency of the air source heat pump unit is generally poor, and the water in the lower part of the water tank cannot be effectively heated efficiently. The effect of reducing the local temperature difference of the water in the water tank is not obvious. Therefore, controlling the first heating element to be turned on can make up for the insufficient heating effect of the air source heat pump unit and ensure a stable and continuous supply of hot water. When the outdoor ambient temperature is greater than or equal to the third preset temperature value, the heating efficiency of the air source heat pump unit is better and can fully heat the water in the lower part of the water tank. Therefore, controlling the first heating element to be turned off can avoid unnecessary energy waste and improve the overall energy efficiency of the system.

[0063] It should be noted that although the present invention is described using the example of a first temperature sensor being located at the upper portion of the water tank and a second temperature sensor being located at the lower portion, this is not intended to limit the scope of protection of the present invention. As long as the first and second temperature sensors are located at different positions in the water tank to detect local temperature differences within the water tank, their specific arrangements can be adjusted. For example, the first temperature sensor could be located in the middle of the water tank and the second temperature sensor could be located at the lower portion of the water tank. Such adjustments do not deviate from the principles of the present invention and are within the scope of protection of the present invention.

[0064] A possible implementation of the heat pump water system of the present invention is described below, which specifically includes the following steps:

[0065] Step S401: Determine whether the first water temperature minus the second water temperature is less than 3° C. If so, proceed to step S402. If not, proceed to step S406.

[0066] Step S402: Determine whether the set water temperature minus the first water temperature is less than 15° C. If so, proceed to step S403. If not, proceed to step S405.

[0067] Step S403: Determine whether the outdoor ambient temperature is less than 0°C. If so, execute step S405. If not, execute step S404.

[0068] Step S404: controlling the first heating element to be turned off, and controlling the second heating element to be turned off.

[0069] Step S405: controlling the first heating element to be turned off and controlling the second heating element to be turned on.

[0070] Step S406: Determine whether the set water temperature minus the first water temperature is less than 15° C. If so, execute step S410. If not, execute step S407.

[0071] Step S407: Determine whether the outdoor ambient temperature is less than 0°C. If so, proceed to step S408. If not, proceed to step S409.

[0072] Step S408: controlling the first heating element to turn on; controlling the second heating element to turn on.

[0073] Step S409: controlling the first heating element to turn on; controlling the second heating element to turn off.

[0074] Step S410: Determine whether the outdoor ambient temperature is less than 0°C. If so, execute step S409. If not, execute step S404.

[0075] Although the various steps in the above embodiment are described in the above-mentioned order, those skilled in the art will understand that in order to achieve the effect of this embodiment, different steps do not have to be executed in such an order. They can be executed simultaneously (in parallel) or in a reverse order. For example, step S301, step S302 and step S303 can be executed in any order or in parallel. These simple changes are within the scope of protection of the present invention.

[0076] Those skilled in the art will appreciate that the heat pump water system described above includes other known structures, such as a processor, a controller, and a memory. The memory includes, but is not limited to, random access memory, flash memory, read-only memory, programmable read-only memory, volatile memory, non-volatile memory, serial memory, parallel memory, or registers. The processor includes, but is not limited to, a CPLD / FPGA, a DSP, an ARM processor, a MIPS processor, and the like. To unnecessarily obscure the embodiments of the present disclosure, these known structures are not shown in the accompanying drawings. The memory is suitable for storing multiple program codes, which are suitable for being loaded and executed by the processor to execute the control method of the heat pump water system.

[0077] Thus far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present invention.

Claims

1. A control method for a heat pump water system, characterized in that: The heat pump water system comprises: water tank; an air source heat pump unit, configured to directly or indirectly provide heat to the water tank in a heating mode; an auxiliary heating device, used for providing heat to the water tank when in an on state; a first temperature sensor, configured to detect a first water temperature of the water tank; a second temperature sensor, configured to detect a second water temperature of the water tank at a position different from that of the first temperature sensor; Ambient temperature sensor, used to detect outdoor ambient temperature; The control method includes: When the air source heat pump unit is in a heating mode, obtaining the first water temperature, the second water temperature, and the outdoor ambient temperature; Calculating a first temperature difference between the first water temperature and the second water temperature and a second temperature difference between a set water temperature and the first water temperature; Based on the first temperature difference value, the second temperature difference value and the outdoor ambient temperature, the auxiliary heating device is controlled to be turned on and off.

2. The control method of the heat pump water system according to claim 1, characterized in that: The first temperature sensor is arranged at the upper part of the water tank, and the second temperature sensor is arranged at the lower part of the water tank; A heating structure is provided at the lower portion of the water tank, and the auxiliary heating device includes a first heating element and a second heating element, wherein the first heating element is used to heat the heating structure or the first heating element is configured as the heating structure, and the second heating element is used to heat the entire water tank; The step of “controlling the on / off of the auxiliary heating device based on the first temperature difference, the second temperature difference and the outdoor ambient temperature” further includes: Based on the first temperature difference value, the second temperature difference value and the outdoor ambient temperature, the first heating element and the second heating element are controlled to be turned on and off.

3. The control method of the heat pump water system according to claim 2, characterized in that: The step of “controlling the on / off of the first heating element and the second heating element based on the outdoor ambient temperature, the first temperature difference value, and the second temperature difference value” further includes: comparing the first temperature difference value with a first preset temperature value; comparing the second temperature difference value with a second preset temperature value; Comparing the outdoor ambient temperature with a third preset temperature value; Based on the comparison result, the first heating element and the second heating element are controlled to be turned on and off.

4. The control method of the heat pump water system according to claim 3, characterized in that: The step of “controlling the on / off of the first heating element and the second heating element based on the comparison result” further includes: When the first temperature difference is less than the first preset temperature, controlling the first heating element to be turned off; Based on the comparison result between the second temperature difference value and the second preset temperature value, and the comparison result between the outdoor ambient temperature and the third preset temperature value, the second heating element is controlled to be turned on and off.

5. The control method of the heat pump water system according to claim 4, characterized in that: The step of “controlling the second heating element to be turned on and off based on a comparison result between the second temperature difference value and the second preset temperature value, and a comparison result between the outdoor ambient temperature and the third preset temperature value” further includes: When the second temperature difference is less than the second preset temperature value, if the outdoor ambient temperature is less than the third preset temperature value, the second heating element is controlled to be turned on; if the outdoor ambient temperature is greater than or equal to the third preset temperature value, the second heating element is controlled to be turned off; and / or When the second temperature difference is greater than or equal to the second preset temperature value, the second heating element is controlled to turn on.

6. The control method of the heat pump water system according to claim 4 or 5, characterized in that: The step of “controlling the on / off of the first heating element and the second heating element based on the comparison result” further includes: When the first temperature difference is greater than or equal to the first preset temperature value, if the second temperature difference is greater than or equal to the second preset temperature value, control the first heating element to turn on; Based on the comparison result between the outdoor ambient temperature and the third preset temperature value, the on / off of the second heating element is controlled.

7. The control method of the heat pump water system according to claim 6, characterized in that: The step of “controlling the on / off of the second heating element based on a comparison result between the outdoor ambient temperature and the third preset temperature value” further includes: If the outdoor ambient temperature is lower than the third preset temperature value, the second heating element is controlled to be turned on; if the outdoor ambient temperature is greater than or equal to the third preset temperature value, the second heating element is controlled to be turned off.

8. The control method of the heat pump water system according to claim 4 or 5, characterized in that: The step of “controlling the on / off of the first heating element and the second heating element based on the comparison result” further includes: When the first temperature difference is greater than or equal to the first preset temperature value, if the second temperature difference is less than the second preset temperature value, controlling the second heating element to be turned off; Based on the comparison result between the outdoor ambient temperature and the third preset temperature value, the on / off of the first heating element is controlled.

9. The control method of the heat pump water system according to claim 8, characterized in that: The step of “controlling the on / off of the first heating element based on a comparison result between the outdoor ambient temperature and the third preset temperature value” further includes: If the outdoor ambient temperature is lower than the third preset temperature value, the first heating element is controlled to be turned on; if the outdoor ambient temperature is greater than or equal to the third preset temperature value, the first heating element is controlled to be turned off.

10. The control method of the heat pump water system according to claim 2, characterized in that: The second heating element is arranged in the middle of the water tank; and / or The heat pump water system also includes a heat exchange path structure, which is configured to exchange heat with the heat exchanger of the air source heat pump unit. The heating structure is configured as a heat exchange coil, and the heat exchange coil is connected to the heat exchange path structure. The first heating element is configured as an electric heating box, and the electric heating box is connected to the pipeline between the heat exchange path structure and the heat exchange coil.

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