Control method of heat pump water heater and heat pump water heater

Abstract

The invention relates to the technical field of control, and discloses a control method of a heat pump water heater and the heat pump water heater. The control method comprises the steps that when the heat pump water heater is in a water using state, first water temperature and second water temperature are obtained, the first water temperature is used for representing the temperature of a first area close to the top of a water tank, and the second water temperature is used for representing the temperature of a second area; the second water temperature is used for representing the temperature of a second area close to the bottom of the water tank, and if the first water temperature of the water tank meets the first preset temperature condition and the second water temperature does not meet the second preset temperature condition, target heat is determined based on the water inlet temperature, the water inlet flow and the set temperature to determine the first frequency of the compressor; if the first frequency exceeds the corresponding preset compressor frequency of the compressor at the current environment temperature, the frequency of the compressor is adjusted based on the change rate of the first water temperature, and the target frequency of the compressor is obtained; and controlling the compressor to operate at the target frequency. According to the method, the compressor frequency is adjusted under the condition that the upper water temperature meets the requirement, namely the energy efficiency is improved while the user requirement is guaranteed.

Description

Technical Field

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

[0002] Heat pump water heaters, also known as air energy water heaters, are highly efficient and energy-saving hot water supply equipment. Heat pump water heaters use electricity to drive the compressor. The high-pressure liquid working fluid passes through the expansion valve and evaporates into gas in the evaporator, absorbing a large amount of heat energy from the air. The gaseous working fluid is compressed by the compressor into a high-temperature, high-pressure liquid, and then enters the condenser to release heat and heat the water. This process is cyclically repeated to achieve water heating.

[0003] Existing heat pump water heaters usually use a single circulation mode when heating. The performance of the heat pump is usually related to the ambient temperature. When the ambient temperature is low, the heating efficiency of the heat pump will decrease, resulting in increased energy consumption. When the existing heat pump water heater is in a water-using state and needs to be supplemented with heat, the heating capacity of the heat pump is generally adjusted according to the ambient temperature. It does not comprehensively consider the remaining available hot water in the heat pump water tank, resulting in the compressor often not operating at a high-efficiency frequency under the current ambient temperature, resulting in poor energy efficiency of the heat pump, and there is still room for improvement. Summary of the invention

[0004] The technical problem solved by the present invention is to provide a control method for a heat pump water heater and a heat pump water heater, which effectively solves the problem that it is difficult to balance energy efficiency and water demand during water use.

[0005] The above technical problems are solved by the following technical solutions:

[0006] A control method for a heat pump water heater, the method comprising:

[0007] When the heat pump water heater is in a water-using state, a first water temperature and a second water temperature are obtained, wherein the first water temperature is used to characterize the temperature of a first area near the top of the water tank, and the second water temperature is used to characterize the temperature of a second area near the bottom of the water tank. If the first water temperature of the water tank meets the first preset temperature condition and the second water temperature does not meet the second preset temperature condition, the target heat is determined based on the inlet water temperature, the inlet water flow rate and the set temperature, and the first frequency of the compressor is determined based on the target heat; if the first frequency exceeds the preset compressor frequency corresponding to the compressor at the current ambient temperature, the frequency of the compressor is adjusted based on the rate of change of the first water temperature to obtain the target frequency of the compressor; and the compressor is controlled to operate at the target frequency.

[0008] Compared with the background technology, the control method of the heat pump water heater of the present invention has the following beneficial effects:

[0009] This method obtains a first water temperature of a first area near the top of the water tank and a second water temperature of a second area near the bottom of the water tank. When the heat pump is in a water-using state, if the first water temperature of the water tank meets the first preset temperature condition and the second water temperature does not meet the second preset temperature condition, it means that the water temperature at the top of the water tank meets the water-using temperature requirement and the water temperature at the bottom of the water tank does not meet the water-using temperature requirement, so there is a need for energy replenishment. First, the first frequency of the compressor is determined by the target heat. If the first frequency exceeds the preset compressor frequency corresponding to the compressor at the current ambient temperature, it means that the compressor is not operating at a high energy-efficiency frequency. On this basis, the change rate of the first water temperature is obtained to judge the hot water usage, so as to further adjust the frequency of the compressor. Therefore, when the change rate of the first water temperature is small, that is, the hot water usage is small, the compressor is allowed to be controlled to replenish heat at a high energy-efficiency frequency. When the upper water temperature meets the water-using temperature requirement, the water temperature is stabilized or the rate of decrease of the upper water temperature is delayed, thereby improving the energy efficiency of the heat pump while ensuring the user's comfort.

[0010] In one embodiment, adjusting the frequency of the compressor based on the rate of change of the first water temperature to obtain the target frequency of the compressor includes:

[0011] Acquiring the first water temperature based on a preset time interval, and determining a rate of change of the first water temperature based on a change amount of the first water temperature within the preset time interval;

[0012] Comparing the change rate of the first water temperature with a preset rate threshold to obtain a first comparison result;

[0013] Compare the first water temperature at the current moment with a third preset temperature condition to obtain a second comparison result;

[0014] The frequency of the compressor is adjusted based on the first comparison result and the second comparison result to obtain a target frequency of the compressor.

[0015] In one embodiment, adjusting the frequency of the compressor based on the first comparison result and the second comparison result to obtain the target frequency of the compressor includes:

[0016] If the first comparison result indicates that the change rate of the first water temperature is less than or equal to the preset rate threshold, and the second comparison result indicates that the first water temperature satisfies the third preset temperature condition, the target frequency is determined to be the preset compressor frequency corresponding to the current ambient temperature.

[0017] In one embodiment, adjusting the frequency of the compressor based on the first comparison result and the second comparison result to obtain the target frequency of the compressor includes:

[0018] If the first comparison result indicates that the change rate of the first water temperature is greater than the preset rate threshold, or the second comparison result indicates that the first water temperature at the current moment does not meet the third preset temperature condition, the target frequency is determined to be the first frequency.

[0019] In one embodiment, the method further comprises:

[0020] If the first water temperature does not satisfy the first preset temperature condition and the second water temperature does not satisfy the second preset temperature condition, obtaining a preset compressor frequency corresponding to the current ambient temperature;

[0021] The compressor is controlled to operate at the preset compressor frequency until the second water temperature meets a fourth preset temperature condition.

[0022] In one embodiment, determining the first frequency of the compressor based on the target heat comprises:

[0023] The first frequency of the compressor corresponding to the heat interval in which the target heat is located is determined based on a preset relationship table, wherein the preset relationship table includes a correspondence between the heat interval and the frequency of the compressor.

[0024] In one embodiment, the method further comprises:

[0025] If it is detected that the heat pump water heater has a water outflow, it is determined that the heat pump water heater is in the water use state.

[0026] In one embodiment, determining the target heat based on the inlet water temperature, the inlet water flow rate and the set temperature includes:

[0027] Determine the temperature difference based on the inlet water temperature and the set temperature;

[0028] A target heat quantity is calculated based on the temperature difference and the water inlet flow rate.

[0029] The above technical problems are solved by the following technical solutions:

[0030] A heat pump water heater, comprising:

[0031] A controller for executing any of the above-mentioned control methods for a heat pump water heater; a compressor and a water tank, wherein a water inlet temperature sensor and a water inlet flow sensor are arranged on the water inlet pipe of the water tank, and the water tank is provided with a first water tank temperature sensor and a second water tank temperature sensor.

[0032] In one embodiment, the heat pump water heater further comprises:

[0033] A four-way valve, a fan, an evaporator, an electronic expansion valve, and a condensing heat exchanger are arranged on the refrigeration cycle loop, the compressor is connected to the evaporator and the condensing heat exchanger respectively through the four-way valve, the electronic expansion valve is arranged on the pipeline between the evaporator and the condensing heat exchanger, and the evaporator is provided with a fan;

[0034] The water tank also includes a heat exchanger, a water tank outlet pipe and a heat exchanger outlet water temperature sensor; the heat exchanger outlet pipe is provided with a heat exchanger outlet water temperature sensor, the heat exchanger inlet pipe is provided with a DC water pump and a water circuit one-way valve; the water tank outlet pipe is provided with a water outlet flow sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0036] Figure 1 A schematic diagram of a heat pump water heater according to an embodiment of the present invention;

[0037] Figure 2 A schematic flow chart of a control method for a heat pump water heater according to an embodiment of the present invention;

[0038] Figure 3 The present invention is a flow chart of a control method for a heat pump water heater according to an embodiment of the present invention.

[0039] Description of reference numerals:

[0040] 1. Water tank; 2. Water tank outlet pipe; 3. First water tank temperature sensor; 4. Second water tank temperature sensor; 5. Water inlet pipe of water tank 1; 6. Water inlet pipe of heat exchanger; 7. DC water pump; 8. Water channel one-way valve; 9. Heat exchanger outlet water temperature sensor; 10. Heat exchanger outlet pipe; 11. Compressor; 12. Four-way valve; 13. Condensing heat exchanger; 14. Electronic expansion valve; 15. Evaporator; 16. Fan. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0042] In the description of the present application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0043] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0044] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "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 a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0045] According to an embodiment of the present invention, a heat pump water heater is provided. Figure 1 As shown, it includes a controller, a compressor 11 and a water tank 1. The controller is used to execute the control method of the heat pump water heater. An inlet water temperature sensor and an inlet water flow sensor are arranged on the water inlet pipe 5 of the water tank 1, and the water tank 1 is provided with a first water tank temperature sensor 3 and a second water tank temperature sensor 4.

[0046] In one embodiment, the heat pump water heater further comprises: a four-way valve 12, a fan 16, an evaporator 15, an electronic expansion valve 14, and a condensing heat exchanger 13 arranged on the refrigeration cycle. The compressor 11 is connected to the evaporator 15 and the condensing heat exchanger 13 respectively through the four-way valve 12, the electronic expansion valve 14 is arranged on the pipeline between the evaporator 15 and the condensing heat exchanger 13, and the evaporator 15 is provided with a fan 16.

[0047] The water tank 1 also includes a heat exchanger, a water tank outlet pipe 2, and a heat exchanger outlet water temperature sensor 9. The heat exchanger is arranged inside the water tank 1, the heat exchanger outlet water temperature sensor 9 is arranged on the heat exchanger outlet pipe 10, the heat exchanger inlet pipe 6 is provided with a direct current water pump 7 and a water circuit check valve 8; the water tank outlet pipe 2 is provided with an outlet water flow sensor.

[0048] The controller in the heat pump water heater provided in the embodiment of the present invention can be used to execute the control method of the heat pump water heater, and intelligently adjust the working frequency of the compressor in the heat pump water heater according to the set water temperature, water inlet flow rate and other parameters. The water tank is provided with a water inlet temperature sensor, a water inlet flow rate sensor, a first water tank temperature sensor, a second water tank temperature sensor, a heat exchanger and other components. Among them, the first water tank temperature sensor is arranged in a first area near the top of the water tank, and is used to measure the water temperature of the first area, wherein the first area is close to the water outlet pipe of the water tank, so the water temperature measured by the first water tank temperature is close to the water outlet temperature of the water tank. The second water tank temperature sensor is arranged in a second area near the bottom of the water tank, and can be used to measure the water temperature of the bottom area of ​​the water tank, wherein the water temperature of the second area is close to the water inlet pipe of the water tank, so the water temperature measured by the second water tank temperature is close to the water inlet temperature of the water tank.

[0049] When the controller receives the heating command, the four-way valve on the refrigeration cycle is switched to the heating mode, so that the high-temperature and high-pressure refrigerant discharged from the compressor enters the condensing heat exchanger. In the condensing heat exchanger, the refrigerant releases heat to the water, causing the water temperature to rise. At the same time, the condensed refrigerant becomes a low-temperature and high-pressure liquid, and enters the evaporator after throttling and reducing the pressure through the electronic expansion valve. In the evaporator, the refrigerant absorbs the heat of the surrounding environment and evaporates, becoming a low-temperature and low-pressure gas. At this time, the fan starts to accelerate the air flow around the evaporator and improve the heat exchange efficiency. The evaporated refrigerant enters the compressor again for compression, completing a heating cycle.

[0050] According to an embodiment of the present invention, a control method for a heat pump water heater is provided, which is applied to a controller of the heat pump water heater. Figure 2 As shown, the method includes:

[0051] Step S101, when the heat pump water heater is in a water-using state, obtain the first water temperature and the second water temperature. If the first water temperature of the water tank meets the first preset temperature condition and the second water temperature does not meet the second preset temperature condition, determine the target heat based on the inlet water temperature, the inlet water flow rate and the set temperature, and determine the first frequency of the compressor based on the target heat.

[0052] Among them, the first water temperature is used to characterize the temperature of the first area near the top of the water tank, and the second water temperature is used to characterize the temperature of the second area near the bottom of the water tank. When the heat pump water heater is in a water-using state, the first water temperature and the second water temperature of the water tank are detected. Specifically, the first water temperature and the second water temperature can be measured by the first water tank temperature sensor and the second water tank temperature sensor, respectively. The first preset temperature condition and the second preset temperature condition can be a set temperature threshold, or a water temperature change, etc., which are not specifically limited here. Taking the first preset temperature condition as the first preset temperature threshold and the second preset temperature condition as the second preset temperature threshold as an example, the first water temperature satisfies the first preset temperature condition, which means that the first water temperature is greater than or equal to the first preset temperature threshold, and the second water temperature does not satisfy the second preset temperature condition, which means that the second water temperature is less than the second preset temperature threshold. The first preset temperature condition can be a water temperature set by the user.

[0053] The inlet water temperature can be measured by the inlet water temperature sensor provided on the inlet water pipe, the inlet water flow rate can be measured by the inlet water flow rate sensor provided on the inlet water pipe, and the set temperature refers to the desired outlet water temperature, which can be set by the user. The target heat required to make the outlet water temperature reach the set temperature is calculated based on the inlet water temperature, the inlet water flow rate and the set temperature. The first frequency of the compressor is determined according to the target heat, and the first frequency is the operating frequency of the compressor that can provide the required target heat under the current working conditions.

[0054] Step S102: if the first frequency exceeds the preset compressor frequency corresponding to the compressor at the current ambient temperature, the frequency of the compressor is adjusted based on the change rate of the first water temperature to obtain a target frequency of the compressor.

[0055] The compressor has a corresponding optimal operating frequency under different temperature environments, that is, the preset compressor frequency. The correspondence between the ambient temperature and the preset compressor frequency is pre-stored in the controller in the form of a data table. Specifically, multiple ambient temperature thresholds can be set according to the compressor performance curve, and multiple temperature intervals can be divided based on the multiple ambient temperature thresholds. Different temperature intervals have corresponding optimal operating frequencies. After obtaining the current ambient temperature, the temperature interval in which the current ambient temperature is located is determined, and then the optimal operating frequency of the current compressor corresponding to the temperature interval can be queried, that is, the corresponding preset compressor frequency under the current ambient temperature.

[0056] The first frequency is compared with the preset compressor frequency. If the first frequency exceeds the preset compressor frequency, if the compressor runs at the first frequency, it may cause problems such as decreased energy efficiency or compressor overload. Therefore, when the first frequency exceeds the preset compressor frequency corresponding to the current ambient temperature, the frequency of the compressor is dynamically adjusted according to the rate of change of the first water temperature. The rate of change of the first water temperature is the speed at which the first water temperature rises or falls within a certain period of time. In the water tank, due to the thermophysical properties of water, hot water will be in the upper part of the water tank and cold water will be near the lower part of the water tank. As long as the upper water temperature can meet user needs, the temperature fluctuation of the outlet water will not be too large.

[0057] Step S103, controlling the compressor to operate at a target frequency.

[0058] After determining the target frequency, the controller sends a control signal to the compressor to control the compressor to operate according to the target frequency.

[0059] The control method of the heat pump water heater provided in the embodiment of the present invention includes: when the heat pump water heater is in a water-using state, if the first water temperature of the water tank meets the first preset temperature condition and the second water temperature does not meet the second preset temperature condition, then determining the target heat based on the inlet water temperature, the inlet water flow rate and the set temperature, and determining the first frequency of the compressor based on the target heat, wherein the first water temperature is used to characterize the temperature of the first area near the top of the water tank, and the second water temperature is used to characterize the temperature of the second area near the bottom of the water tank; if the first water temperature of the water tank meets the first preset temperature condition and the second water temperature does not meet the second preset temperature condition, it means that the water temperature at the top of the water tank meets the water-using temperature requirement and the water temperature at the bottom of the water tank is not enough. To meet the water temperature demand, there is a need for energy replenishment. First, the first frequency of the compressor is determined by the target heat. If the first frequency exceeds the preset compressor frequency corresponding to the current ambient temperature, it means that the compressor is not operating at a high-efficiency frequency. On this basis, the change rate of the first water temperature is obtained to judge the hot water usage, so as to further adjust the frequency of the compressor. When the change rate of the first water temperature is small, that is, the hot water usage is small, the compressor is allowed to be controlled to replenish heat at a high-efficiency frequency. When the upper water temperature meets the water temperature demand, the water temperature is stabilized or the rate of decrease of the upper water temperature is slowed down, thereby improving the energy efficiency of the heat pump while ensuring the user's comfort.

[0060] In some optional implementations, the method further includes: if it is detected that the heat pump water heater has a water outlet flow, determining that the heat pump water heater is in a water use state.

[0061] A water outlet flow sensor is also provided on the water outlet pipe of the water tank, which can detect whether there is water outlet flow. If water flow is detected, it means that the water tank is discharging water, that is, the heat pump water heater is currently in water use state.

[0062] In some optional embodiments, determining the target heat based on the inlet water temperature, the inlet water flow rate and the set temperature in the above step S101 includes: determining the temperature difference based on the inlet water temperature and the set temperature; and calculating the target heat based on the temperature difference and the inlet water flow rate.

[0063] After obtaining the inlet water temperature and the set temperature, calculate the temperature difference between the inlet water temperature and the set temperature. On the basis of determining the temperature difference and the inlet water flow rate, combined with the heat calculation formula, taking into account the specific heat capacity and density of water, the target heat is obtained by calculating the product of the temperature difference, the inlet water flow rate, the specific heat capacity and the density.

[0064] In some optional embodiments, determining the first frequency of the compressor based on the target heat in step S101 includes: determining the first frequency of the compressor corresponding to the heat interval where the target heat is located based on a preset relationship table. The preset relationship table includes a correspondence between the heat interval and the frequency of the compressor.

[0065] The preset relationship table can be stored in the controller in the form of a data table. According to experimental data or empirical values, the corresponding relationship between different heat intervals and different operating frequencies of the compressor is established, and each heat interval has a corresponding operating frequency. The preset relationship table is formulated in the system design stage based on the performance curve of the compressor, the system energy efficiency ratio, and possible user needs. The division of heat intervals can be divided according to actual needs and the power of the heat pump water heater.

[0066] After the target heat is determined, the heat interval in which the target heat is located can be searched in the preset relationship table, and then the first frequency of the corresponding compressor can be determined according to the heat interval.

[0067] Optionally, if the target heat is exactly at the boundary of a certain heat range, the system may select a corresponding frequency according to a preset rule (such as rounding up or rounding down).

[0068] According to an embodiment of the present invention, a control method for a heat pump water heater is provided, which is applied to the controller of the heat pump water heater. The method comprises:

[0069] Step S201, when the heat pump water heater is in a water-using state, obtain the first water temperature and the second water temperature. If the first water temperature of the water tank meets the first preset temperature condition and the second water temperature does not meet the second preset temperature condition, determine the target heat based on the inlet water temperature, the inlet water flow rate and the set temperature, and determine the first frequency of the compressor based on the target heat.

[0070] For details, please see Figure 1 Step S101 of the illustrated embodiment will not be described in detail here.

[0071] Step S202: If the first frequency exceeds the preset compressor frequency corresponding to the compressor at the current ambient temperature, the frequency of the compressor is adjusted based on the change rate of the first water temperature to obtain a target frequency of the compressor.

[0072] Specifically, step S202 includes:

[0073] Step S2021, obtaining the first water temperature based on a preset time interval, and determining the change rate of the first water temperature based on the change amount of the first water temperature within the preset time interval.

[0074] If the first frequency exceeds the preset compressor frequency corresponding to the compressor at the current ambient temperature, the change rate of the first water temperature is calculated. The first water temperature is periodically obtained based on a preset time interval, and the change amount of the first water temperature within the preset time interval is calculated, and the change rate of the first water temperature is determined by calculating the ratio of the change amount and the preset time interval. The change rate of the first water temperature reflects the speed at which the first water temperature rises or falls.

[0075] Step S2022: compare the change rate of the first water temperature with a preset rate threshold to obtain a first comparison result.

[0076] The preset rate threshold is a value set according to actual needs, and the first comparison result includes the magnitude relationship between the change rate of the first water temperature and the preset rate threshold.

[0077] Step S2023, comparing the first water temperature at the current moment with the third preset temperature condition to obtain a second comparison result.

[0078] The third preset temperature condition may be a specific temperature value, a water temperature range, etc. The first water temperature at the current moment is compared with the third preset temperature condition, and the second comparison result includes whether the first water temperature at the current moment meets the third preset temperature condition.

[0079] Step S2024: adjusting the frequency of the compressor based on the first comparison result and the second comparison result to obtain a target frequency of the compressor.

[0080] The frequency of the compressor is adjusted based on the first comparison result and the second comparison result, and the adjusted frequency is the target frequency.

[0081] In some optional embodiments, the above step S2024 includes: if the first comparison result indicates that the change rate of the first water temperature is less than or equal to a preset rate threshold, and the second comparison result indicates that the first water temperature satisfies a third preset temperature condition, then the target frequency is determined to be the preset compressor frequency corresponding to the current ambient temperature.

[0082] If the first comparison result indicates that the change rate of the first water temperature is less than or equal to the preset rate threshold, it indicates that the water temperature change is small or meets the set change range. The second comparison result indicates that the first water temperature meets the third preset temperature condition, indicating that the first water temperature meets the set requirements, and the compressor is controlled to operate at the preset compressor frequency corresponding to the current ambient temperature, that is, the optimal operating frequency corresponding to the current ambient temperature.

[0083] In the scenario of this embodiment, the compressor is controlled to heat with the best energy efficiency. The preset compressor frequency is set based on comprehensive consideration of factors such as the compressor performance, ambient temperature, and the energy efficiency ratio of the system, indicating the frequency at which the compressor can operate efficiently and stably in this environment.

[0084] In some optional embodiments, the above step S2024 includes: if the first comparison result indicates that the change rate of the first water temperature is greater than a preset rate threshold, or the second comparison result indicates that the first water temperature at the current moment does not meet the third preset temperature condition, then determining the target frequency to be the first frequency.

[0085] If the first preset temperature condition and the third preset temperature condition are both temperature thresholds, the third preset temperature threshold is greater than the first preset temperature threshold.

[0086] If the first comparison result indicates that the change rate of the first water temperature is greater than the preset rate threshold, it means that the water temperature is changing rapidly, which may be caused by the user using a large amount of water; if the second comparison result indicates that the first water temperature at the current moment does not meet the third preset temperature condition, it means that the current first water temperature has not yet met the user or system requirements, and the compressor is controlled to operate at the first frequency.

[0087] The change rate of the first water temperature is greater than the preset rate threshold or the first water temperature at the current moment does not meet the third preset temperature condition, indicating that in the process of forcing the equipment to heat at the best energy efficiency, the user is still continuously using water and the water consumption is large. In order to prevent large fluctuations in the outlet water temperature, the forced heat pump to heat at the best energy efficiency is ended in advance to ensure the user's water comfort.

[0088] Step S203, controlling the compressor to operate at a target frequency.

[0089] For details, please see Figure 1 Step S103 of the illustrated embodiment will not be described in detail here.

[0090] According to an embodiment of the present invention, a control method for a heat pump water heater is provided, which is applied to a controller of the heat pump water heater. Figure 3 As shown, the method includes:

[0091] Step S301: if the first water temperature does not satisfy the first preset temperature condition and the second water temperature does not satisfy the second preset temperature condition, then obtain a preset compressor frequency corresponding to the current ambient temperature.

[0092] Step S302, controlling the compressor to operate at a preset compressor frequency until the second water temperature meets a fourth preset temperature condition.

[0093] The first preset temperature condition and the second preset temperature condition can be a set temperature threshold, or a water temperature change, etc., which are not specifically limited here. Taking the first preset temperature condition as the first preset temperature threshold and the second preset temperature condition as the second preset temperature threshold as an example, if the first water temperature does not meet the first preset temperature condition, it means that the first water temperature is less than the first preset temperature threshold, and if the second water temperature does not meet the second preset temperature condition, it means that the second water temperature is less than the second preset temperature threshold. The compressor has a corresponding optimal operating frequency under different temperature environments, that is, a preset compressor frequency, and the corresponding relationship between the ambient temperature and the preset compressor frequency is pre-stored in the controller in the form of a data table. Specifically, multiple ambient temperature thresholds can be set according to the compressor performance curve, and multiple temperature intervals can be divided based on multiple ambient temperature thresholds. Different temperature intervals have corresponding optimal operating frequencies. After obtaining the current ambient temperature, the temperature interval in which the current ambient temperature is located is determined, and then the optimal operating frequency of the current compressor corresponding to the temperature interval can be queried, that is, the preset compressor frequency corresponding to the current ambient temperature.

[0094] The compressor is controlled to operate at an optimal frequency corresponding to the current ambient temperature until the lower water temperature meets the fourth preset temperature condition. If the fourth preset temperature condition is the fourth preset temperature threshold and the second preset temperature condition is the second preset temperature threshold, the fourth preset temperature threshold may be set higher than the second preset temperature threshold.

[0095] The control method of the heat pump water heater provided in this embodiment can control the compressor to maintain the operation at the optimal operating frequency, maximize the use of energy, and reduce the number of starts and stops and protect equipment components by maintaining a stable operating frequency until the lower water temperature reaches the preset conditions.

[0096] In the specific contents of the above-mentioned specific implementation methods, the various technical features can be combined in any non-contradictory manner. In order to make the description concise, not all possible combinations of the above-mentioned technical features are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0097] The specific contents of the above specific embodiments only express several embodiments of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims.

Claims

1. A control method for a heat pump water heater, characterized in that: The method comprises: When the heat pump water heater is in a water-using state, a first water temperature and a second water temperature are obtained, wherein the first water temperature is used to characterize the temperature of a first area near the top of the water tank, and the second water temperature is used to characterize the temperature of a second area near the bottom of the water tank. If the first water temperature of the water tank meets a first preset temperature condition and the second water temperature does not meet a second preset temperature condition, a target heat is determined based on the inlet water temperature, the inlet water flow rate, and the set temperature, and a first frequency of the compressor is determined based on the target heat; If the first frequency exceeds a preset compressor frequency corresponding to the compressor at the current ambient temperature, adjusting the frequency of the compressor based on the rate of change of the first water temperature to obtain a target frequency of the compressor; The compressor is controlled to operate at the target frequency.

2. The control method of the heat pump water heater according to claim 1, characterized in that: The step of adjusting the frequency of the compressor based on the rate of change of the first water temperature to obtain a target frequency of the compressor includes: Acquiring the first water temperature based on a preset time interval, and determining a rate of change of the first water temperature based on a change amount of the first water temperature within the preset time interval; Comparing the change rate of the first water temperature with a preset rate threshold to obtain a first comparison result; Compare the first water temperature at the current moment with a third preset temperature condition to obtain a second comparison result; The frequency of the compressor is adjusted based on the first comparison result and the second comparison result to obtain a target frequency of the compressor.

3. The control method of the heat pump water heater according to claim 2, characterized in that: The adjusting the frequency of the compressor based on the first comparison result and the second comparison result to obtain the target frequency of the compressor includes: If the first comparison result indicates that the change rate of the first water temperature is less than or equal to the preset rate threshold, and the second comparison result indicates that the first water temperature satisfies the third preset temperature condition, the target frequency is determined to be the preset compressor frequency corresponding to the current ambient temperature.

4. The control method of the heat pump water heater according to claim 2, characterized in that: The adjusting the frequency of the compressor based on the first comparison result and the second comparison result to obtain the target frequency of the compressor includes: If the first comparison result indicates that the change rate of the first water temperature is greater than the preset rate threshold, or the second comparison result indicates that the first water temperature at the current moment does not meet the third preset temperature condition, the target frequency is determined to be the first frequency.

5. The control method of the heat pump water heater according to claim 1, characterized in that: The method further comprises: If the first water temperature does not satisfy the first preset temperature condition and the second water temperature does not satisfy the second preset temperature condition, obtaining a preset compressor frequency corresponding to the current ambient temperature; The compressor is controlled to operate at the preset compressor frequency until the second water temperature meets a fourth preset temperature condition.

6. The control method of the heat pump water heater according to claim 1, characterized in that: The determining a first frequency of the compressor based on the target heat comprises: The first frequency of the compressor corresponding to the heat interval in which the target heat is located is determined based on a preset relationship table, wherein the preset relationship table includes a correspondence between the heat interval and the frequency of the compressor.

7. The control method of the heat pump water heater according to claim 1, characterized in that: The method further comprises: If it is detected that the heat pump water heater has a water outflow, it is determined that the heat pump water heater is in the water use state.

8. The control method of the heat pump water heater according to claim 1, characterized in that: The determining of the target heat based on the inlet water temperature, the inlet water flow rate and the set temperature includes: Determine the temperature difference based on the inlet water temperature and the set temperature; A target heat quantity is calculated based on the temperature difference and the water inlet flow rate.

9. A heat pump water heater, characterized in that: include: A controller, used to execute the control method of the heat pump water heater according to any one of claims 1 to 8; A compressor and a water tank, wherein a water inlet temperature sensor and a water inlet flow sensor are arranged on the water inlet pipe of the water tank, and the water tank is provided with a first water tank temperature sensor and a second water tank temperature sensor.

10. The heat pump water heater according to claim 9, characterized in that: Also includes: A four-way valve, a fan, an evaporator, an electronic expansion valve, and a condensing heat exchanger are arranged on the refrigeration cycle loop, the compressor is connected to the evaporator and the condensing heat exchanger respectively through the four-way valve, the electronic expansion valve is arranged on the pipeline between the evaporator and the condensing heat exchanger, and the evaporator is provided with a fan; The water tank also includes a heat exchanger, a water tank outlet pipe and a heat exchanger outlet water temperature sensor; the heat exchanger outlet pipe is provided with a heat exchanger outlet water temperature sensor, the heat exchanger inlet pipe is provided with a DC water pump and a water circuit one-way valve; the water tank outlet pipe is provided with a water outlet flow sensor.

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