Control method of air source heat pump water system and air source heat pump water system

Abstract

The invention relates to an air source heat pump water system, in particular to a control method of the air source heat pump water system and the air source heat pump water system, and aims to solve the problem that frequent shutdown is easily caused by instantaneous rise of high pressure during heating of an existing air source heat pump water system. In order to achieve the purpose, the control method comprises the steps that in a heating mode, a high-pressure side parameter value is obtained; and when the high-pressure side parameter value is increased in the preset adjusting interval, the frequency of the compressor is controlled to be reduced or unchanged, and the rotating speed of the outdoor fan is controlled to be reduced. When the high-pressure side parameter value falls into the preset adjusting interval and continues to rise, it is proved that the system has the risk that the high-pressure pressure is instantaneously too high, due to the fact that the instantaneous high-pressure pressure duration time is short, the rotating speed of the outdoor fan is controlled to be reduced while the frequency of the compressor is controlled to be forbidden to rise, and the system can be effectively operated while it is guaranteed that the system operates effectively. And instant overhigh pressure of the high pressure can be timely handled, so that frequent shutdown of the system is avoided.

Description

Technical Field

[0001] The present invention relates to an air source heat pump water system, and specifically provides a control method for an air source heat pump water system and an air source heat pump water system. Background Art

[0002] In recent years, air source heat pump water systems have been widely used in various buildings and facilities. Especially in scenarios with high heating demand in winter and relatively strict requirements for environmental temperature, they have demonstrated significant energy-saving effects. However, during actual use, problems frequently occur in the high-pressure regulation of air source heat pump water systems in the heating state, and the phenomenon of transiently excessive high pressure is likely to occur within a short period. Especially when the external air temperature is not particularly low but users have relatively high requirements for the outlet water temperature, high-pressure regulation becomes more difficult.

[0003] The high-pressure problem of the heat pump water system often shows transience. However, the current control logic has a relatively lagging response speed to high-pressure changes, making it difficult for the system to respond in a timely manner, resulting in frequent shutdowns, which has an adverse impact on the operating stability of the equipment and further reduces the user experience.

[0004] Correspondingly, there is a need in the art for a new control method for an air source heat pump water system and an air source heat pump water system to solve the problem that the existing air source heat pump water system is prone to frequent shutdowns due to transient increases in high-pressure during heating. Summary of the Invention

[0005] The present invention aims to solve the above technical problems, that is, to solve the problem that the existing air source heat pump water system is prone to frequent shutdowns due to transient increases in high-pressure during heating.

[0006] In a first aspect, the present invention provides a control method for an air source heat pump water system, characterized in that the control method includes: in the heating mode, obtaining the high-pressure side parameter value; when the high-pressure side parameter value increases within a preset adjustment range, controlling the frequency of the compressor to decrease or remain unchanged, and controlling the rotational speed of the outdoor fan to decrease; wherein the high-pressure side parameter is the high-pressure value or the saturation temperature value corresponding to the high-pressure value.

[0007] In the heating mode of the air source heat pump water system, the outdoor heat exchanger is actually an evaporator, while the indoor heat exchanger acts as a condenser and exchanges heat with the water tank to heat the water in the water tank. If the compressor frequency is controlled to remain unchanged or decrease, that is, the increase of the compressor frequency is prohibited, the rising speed of the high-pressure side pressure can be slowed down. If the rotational speed of the outdoor fan is controlled to decrease, the air flow rate through the evaporator decreases, the heat exchange effect of the evaporator will decline, the amount of gaseous refrigerant decreases, and the load on the compressor is reduced, thereby effectively suppressing the rising trend of the high-pressure. When the high-pressure side parameter value falls within the preset adjustment range and continues to rise, it proves that the system has a risk of transient excessive high pressure. Since the duration of the transient high pressure is short, therefore, while the present invention controls the compressor frequency from increasing, it also controls the rotational speed of the outdoor fan to decrease, so as to make a timely response to the transient excessive high pressure while ensuring the effective operation of the system, effectively suppressing the rise of the high-pressure, and avoiding frequent system shutdowns.

[0008] In an alternative technical solution of the control method of the above air source heat pump water system, the step of "when the high-pressure side parameter value rises within the preset adjustment range, controlling the rotational speed of the outdoor fan to decrease" further includes: when the high-pressure side parameter value rises within the range greater than the first preset value and less than the second preset value, controlling the rotational speed of the outdoor fan to decrease periodically; and / or when the high-pressure side parameter value rises within the range greater than or equal to the second preset value and less than the third preset value, controlling the rotational speed of the outdoor fan to decrease to the preset minimum rotational speed.

[0009] When the high-pressure side parameter value rises within the range greater than the first preset value and less than the second preset value, by periodically reducing the rotational speed of the outdoor fan and combining with prohibiting the increase of the compressor frequency, the rising of the system high-pressure can be stably suppressed, the stability of the system can be improved, and the service life of the equipment can be extended. When the high-pressure side parameter value rises within the range greater than or equal to the second preset value and less than the third preset value, it proves that the rising trend of the high-pressure has not been effectively suppressed and there is a risk of breaking through the adjustment range. In this case, controlling the rotational speed of the outdoor fan to immediately drop to the minimum, combined with the reduction of the compressor frequency, effectively reduces the system load, and quickly slows down or suppresses the rising trend of the high-pressure, avoiding frequent system shutdowns.

[0010] In an alternative technical solution of the control method of the above air source heat pump water system, the step of "when the high-pressure side parameter value rises within the preset adjustment range, controlling the compressor frequency to decrease or remain unchanged" further includes: when the high-pressure side parameter value rises within the range greater than the first preset value and less than the second preset value, controlling the compressor frequency to decrease or remain unchanged; when the high-pressure side parameter value rises within the range greater than or equal to the second preset value and less than the third preset value, controlling the compressor frequency to decrease.

[0011] Among them, the first preset value serves as the lower limit of the high-pressure side parameter value, and the third preset value serves as the upper limit of the high-pressure side parameter value, thereby forming a preset adjustment range. If the high-pressure side parameter value falls within this range and rises within this range, adjustment needs to be carried out in a timely manner to prevent the high-pressure side parameter value from continuing to rise outside the adjustment range, which may lead to shutdown. In addition to controlling the speed of the outdoor fan to decrease within the adjustment range in the present invention, the compressor frequency can also be continuously controlled to decrease until the high-pressure side parameter value no longer rises. Or the adjustment range is divided into a first range of "greater than the first preset value and less than the second preset value" and a second range of "greater than or equal to the second preset value and less than the third preset value". When the compressor frequency falls within the first range and is on an upward trend, the frequency of the compressor can be controlled to remain unchanged, and the speed of the outdoor fan can be controlled to decrease to slow down or prevent the upward trend of the high-pressure side parameter value; if the high-pressure side parameter value continues to rise and falls within the second range, not only the speed of the outdoor fan needs to be controlled to decrease, but also the compressor frequency needs to be controlled to decrease until the high-pressure side parameter value no longer rises.

[0012] In an alternative technical solution of the above control method for an air-source heat pump water system, the step of "when the high-pressure side parameter value rises within the range of greater than or equal to the second preset value and less than the third preset value, control the compressor frequency to decrease" further includes: when the high-pressure side parameter value rises within the range of greater than or equal to the second preset value and less than the fourth preset value, control the compressor frequency to periodically decrease by a first preset amplitude; when the high-pressure side parameter value rises within the range of greater than or equal to the fourth preset value and less than the third preset value, control the compressor frequency to decrease by a second preset amplitude; after the compressor frequency decreases by the second preset amplitude, control the compressor frequency to periodically decrease by the first preset amplitude; where the second preset amplitude is greater than the first preset amplitude.

[0013] By dividing the decrease of the compressor frequency into two stages, that is, when the high-pressure side parameter value rises within the range of greater than or equal to the second preset value and less than the fourth preset value, controlling the compressor frequency to periodically decrease by a first preset amplitude can moderately reduce the compressor frequency, which is beneficial to the stable operation of the system. At the same time, reducing the speed of the outdoor fan to the lowest speed can effectively suppress the upward trend of the high pressure. When the high-pressure side parameter value rises within the range of greater than or equal to the fourth preset value and less than the third preset value, the system high-pressure still rises and is already close to the alarm value. Therefore, stronger control measures need to be taken. At this time, controlling the compressor frequency to decrease by the second preset amplitude in a timely manner, that is, reducing the compressor frequency by a larger amplitude, can significantly reduce the working load of the compressor in a shorter time and more quickly suppress the continuous rise of the high pressure, and the system can more effectively avoid the high pressure reaching the alarm value or entering a dangerous state. To avoid oscillations or instability caused by over-adjustment, the system will continue to periodically decrease by the first preset amplitude after reducing the second preset amplitude to maintain the balance of the system.

[0014] In the optional technical solution of the control method of the above-mentioned air source heat pump water system, the control method also includes: when the high-pressure side parameter value is greater than or equal to a second preset value and lasts for a first preset time, executing the compressor frequency update step: obtaining the outdoor ambient temperature; based on the outdoor ambient temperature, determining the maximum frequency of the compressor, and controlling the operating frequency of the compressor not to exceed the maximum frequency.

[0015] During heating operation, the second heat exchanger on the outdoor side will exchange heat with the outdoor air, and the outdoor ambient temperature will affect the evaporation pressure of the refrigerant. There is a close synergistic relationship between the frequency of the compressor and the evaporation pressure, and the two together have a significant impact on the high pressure pressure of the system. Therefore, based on the outdoor ambient temperature, the maximum frequency of the compressor is determined, and then the operating frequency of the compressor is controlled not to exceed the maximum frequency, which can prevent the system high pressure from rising sharply, prevent the high pressure protection from being frequently triggered and causing the system to shut down, and optimize the energy efficiency ratio.

[0016] In an optional technical solution of the control method of the above-mentioned air source heat pump water system, the higher the temperature range of the outdoor ambient temperature is, the lower the corresponding maximum frequency of the compressor is.

[0017] If the outdoor ambient temperature is high, the evaporation pressure is already at a high level. At this time, if the compressor frequency is too high, it will cause a substantial increase in the refrigerant circulation flow rate, a sharp increase in the compressor exhaust volume, and then the system's high-pressure pressure will rise rapidly, exceeding the safe range that the system can withstand, and it is very easy to cause serious problems such as the activation of the high-pressure protection device, causing the system to shut down. Therefore, the higher the temperature range of the outdoor ambient temperature of the present invention, the lower the corresponding maximum frequency of the compressor, which can effectively prevent the occurrence of the above problems. On the contrary, in a low-temperature environment, a lower evaporation pressure is combined with a not-low compressor frequency to maintain the system's high-pressure pressure in a reasonable range, ensuring the stable, efficient and safe operation of the heat pump water system.

[0018] In an optional technical solution of the control method of the above-mentioned air source heat pump water system, the control method further includes: when the high-pressure side parameter value is less than or equal to the difference between the second preset value and the preset positive buffer value, exiting the compressor frequency update step.

[0019] The above scheme can effectively avoid the system from excessively limiting the operating frequency of the compressor when the high-pressure pressure returns to normal or is at a lower level, resulting in an unnecessary reduction in the system's heating efficiency. The existence of the positive buffer value allows the compressor frequency update step to be exited only when the high-pressure side parameter value is lower than the second preset value to a certain extent, ensuring that the system returns to normal after the high-pressure pressure is stably reduced to a safe range, effectively preventing repeated fluctuations in the high-pressure side pressure, and ensuring the smooth and reliable operation of the heat pump water system.

[0020] In an alternative technical solution of the above control method for an air-source heat pump water system, the control method further includes: when the high-pressure side parameter value is greater than the maximum value within the adjustment range and lasts for a second preset time, controlling the heat pump water system to shut down.

[0021] In an alternative technical solution of the above control method for an air-source heat pump water system, the control method further includes: when the high-pressure side parameter value is greater than the maximum value within the adjustment range and lasts for a second preset time, sending an alarm message.

[0022] When the high-pressure side parameter value exceeds the maximum value of the adjustment range for a long time, it indicates that the heat pump water system is in a serious high-pressure abnormal state. Continuing to operate may cause excessive pressure on each component of the system, leading to serious faults such as compressor damage and pipeline rupture, and even triggering safety accidents. By shutting down in time, irreversible damage to the heat pump water system due to excessive high-pressure can be effectively avoided, the maintenance cost and risk can be reduced, and the service life of the system can be extended. Sending an alarm message can timely remind the maintenance personnel of the system abnormality so that corresponding countermeasures can be taken in time.

[0023] On the other hand, the present invention also provides an air-source heat pump water system, including: a processor; a memory, the memory being adapted to store a plurality of program codes, and the program codes being adapted to be loaded and run by the processor to execute the control method for the air-source heat pump water system according to any one of the above.

[0024] After the air-source heat pump water system adopts the above control method, it can make timely responses to the instantaneous excessive high-pressure while ensuring the effective operation of the system, effectively suppress the rise of the high-pressure, and avoid frequent shutdowns of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The following describes the preferred embodiments of the present invention with reference to the drawings, in which:

[0026] Figure 1 is a schematic structural diagram of the air-source heat pump water system of the present invention;

[0027] Figure 2 is a main flow chart of the control method for the air-source heat pump water system of the present invention;

[0028] Figure 3 is a possible logic diagram of the control method for the air-source heat pump water system of the present invention.

[0029] Description of the reference numerals:

[0030] 1 - air-source heat pump unit; 11 - compressor; 12 - throttling element; 13 - second heat exchanger; 14 - temperature sensor; 15 - pressure sensor; 2 - water circulation pipeline; 3 - plate heat exchanger. Detailed implementation manners

[0031] The preferred implementation manners of the present invention will be described below with reference to the accompanying drawings. Those skilled in the art should understand that these implementation manners are only used to explain the technical principle of the present invention and are not intended to limit the protection scope of the present invention. Those skilled in the art can make adjustments according to needs to adapt to specific application scenarios.

[0032] 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 air source heat pump water system based on the height direction in the use state. In addition, it should also be noted that in the description of the present invention, unless otherwise clearly specified 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 specific situations. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0033] The present invention provides a control method for an air source heat pump water system. As Figure 1 shown, the heat pump water system includes an air source heat pump unit 1 and a water storage structure. The water storage structure may include a water circulation pipeline 2 structure and / or a water tank, etc. The air source heat pump unit 1 includes a compressor 11, a first heat exchanger, a throttling element 12 (such as an electronic expansion valve or a capillary tube, etc.), and a second heat exchanger 13 that are sequentially connected to form a closed loop. In the heating mode, the second heat exchanger 13 absorbs heat from the outdoor environment to evaporate the refrigerant from a liquid into a low-temperature and low-pressure gas. Then the compressor 11 compresses these gases to form a high-temperature and high-pressure gas. The high-temperature and high-pressure gas refrigerant is sent into the first heat exchanger, and the hot gas refrigerant directly or indirectly transfers its heat to the water storage structure, causing the refrigerant to cool and condense into a liquid. The condensed high-pressure liquid refrigerant is decompressed by the expansion valve and quickly becomes a low-temperature and low-pressure liquid, and then is sent back to the second heat exchanger 13 to start a new cycle.

[0034] Among them, there are various ways for the first heat exchanger to exchange heat with the water storage structure, and the present invention does not make specific limitations on it. For example, when the water storage structure includes a water circulation pipeline 2 structure, a part of the water circulation pipeline 2 structure and the first heat exchanger form a sleeve-type heat exchange structure, a plate heat exchanger 3, or a spiral coil heat exchanger, etc. One end of the water circulation pipeline 2 structure can be configured as an inlet, and the other end can be configured as an outlet. When the water storage structure is configured as a water tank, the first heat exchanger can be configured as a coil or other heat exchange structures, etc. The coil can be wound around the outer wall of the water tank or arranged inside the water tank, etc.

[0035] As a possible implementation, the air source heat pump water system further includes a temperature sensor 14 and a pressure sensor 15. The temperature sensor 14 is used to detect the outdoor ambient temperature. It can be set on the outdoor housing where the second heat exchanger 13 is installed or directly placed outdoors, etc. The pressure sensor 15 is arranged on the pipeline on the side of the compressor exhaust port to detect the high-pressure value of the system.

[0036] The control method of the air source heat pump water system of the present invention will be introduced below. As Figure 2 shown, it specifically includes the following steps.

[0037] Step S100: In the heating mode, obtain the high-pressure side parameter value.

[0038] Step S200: When the high-pressure side parameter value rises within the preset adjustment range, control the frequency of the compressor to decrease or remain unchanged, and control the rotational speed of the outdoor fan to decrease.

[0039] It can be understood that when the air source heat pump water system is in the heating mode, the first heat exchanger releases heat and transfers the heat to the water storage structure to heat the water. Among them, the high-pressure side parameter is the high-pressure value detected by the pressure sensor, or the saturation temperature value corresponding to the high-pressure value. The saturation temperature value corresponding to the high-pressure value can be calculated through thermodynamic formulas, physical property tables or state equations. For a specific refrigerant, a known high-pressure value corresponds to a fixed saturation temperature value. Therefore, by detecting the high-pressure value at the compressor exhaust port, the system can look up the high-pressure value - saturation temperature value relationship table of the refrigerant or use the state equation of the refrigerant to calculate the corresponding saturation temperature.

[0040] Controlling the compressor frequency to remain unchanged or decrease, that is, prohibiting the compressor frequency from rising, can slow down the rising speed of the high-pressure side pressure. Controlling the rotational speed of the outdoor fan to decrease, the air flow rate through the evaporator decreases, the heat exchange effect of the evaporator will decline, the amount of gaseous refrigerant decreases, and the load on the compressor is reduced, thereby effectively suppressing the rising trend of the high-pressure pressure. When the high-pressure side parameter value falls within the preset adjustment range and continues to rise, it proves that the system has a risk of instantaneous excessive high-pressure pressure. Since the duration of the instantaneous high-pressure pressure is short, therefore, while the present invention controls the compressor frequency from rising, it also controls the rotational speed of the outdoor fan to decrease, so that while ensuring the effective operation of the unit, it can promptly respond to the instantaneous excessive high-pressure pressure in a timely manner, effectively suppressing the rising of the high-pressure pressure and avoiding frequent shutdowns of the system.

[0041] Possibly, step S200 further includes: when the high-pressure side parameter value increases within the range greater than the first preset value and less than the second preset value, controlling the frequency of the compressor to decrease or remain unchanged; when the high-pressure side parameter value increases within the range greater than or equal to the second preset value and less than the third preset value, controlling the frequency of the compressor to decrease. Wherein, the first preset value serves as the lower limit of the high-pressure side parameter value, and the third preset value serves as the upper limit of the high-pressure side parameter value, thereby forming a preset adjustment range. If the high-pressure side parameter value falls within this range and rises within this range, adjustment needs to be carried out in a timely manner to prevent the high-pressure side parameter value from continuing to rise outside the adjustment range, which may lead to shutdown. In addition to controlling the speed of the outdoor fan to decrease within the adjustment range, the present invention can also continuously control the frequency of the compressor to decrease until the high-pressure side parameter value no longer rises. Or divide the adjustment range into a first range of "greater than the first preset value and less than the second preset value" and a second range of "greater than or equal to the second preset value and less than the third preset value". When the compressor frequency falls within the first range and is in an upward trend, the frequency of the compressor can be controlled to remain unchanged, and the speed of the outdoor fan can be controlled to decrease to slow down or prevent the upward trend of the high-pressure side parameter value; if the high-pressure side parameter value continues to rise and falls within the second range, not only the speed of the outdoor fan needs to be controlled to decrease, but also the frequency of the compressor needs to be controlled to decrease until the high-pressure side parameter value no longer rises.

[0042] Among them, the first preset value represents the upper limit of the normal level of the high-pressure side parameter value, and the third preset value represents the upper limit at which the high-pressure side parameter value being too high may cause system failures. When the high-pressure side parameter value is greater than the first preset value, it means that the high-pressure exceeds the safe operating range. When the high-pressure side parameter value is greater than the third preset value, it means that the high-pressure is too high and the system may shut down. The value of the second preset value is between the first preset value and the third preset value, and it can divide the adjustment range. Different control strategies for preventing the high-pressure side parameter value from rising can be implemented in different ranges. The present invention does not limit the specific values of the first preset value, the second preset value, and the third preset value, and they can be reasonably adjusted according to the design requirements of the air-conditioning system, refrigerant type, working environment, and safety standards, etc. For example, when the high-pressure side parameter value is the saturation temperature value, the first preset value is 55°C, the second preset value is 58°C, and the third preset value is 65°C. Or the first preset value is 52°C, the second preset value is 56°C, and the third preset value is 63°C, etc. When the high-pressure side parameter value is the high-pressure value, the specific values of the first preset value, the second preset value, and the third preset value can be the corresponding high-pressure values respectively.

[0043] As a possible implementation manner, when the high-pressure side parameter value increases within the range greater than the first preset value and less than the second preset value, the speed of the outdoor fan is controlled to decrease periodically. When the high-pressure side parameter value increases within the range greater than or equal to the second preset value and less than the third preset value, the speed of the outdoor fan is controlled to decrease to the preset minimum speed.

[0044] When the parameter value on the high-pressure side increases within the range greater than the first preset value and less than the second preset value, by periodically reducing the rotational speed of the outdoor fan and combining with prohibiting the increase of the compressor frequency, the increase of the system high-pressure can be smoothly suppressed, the stability of the system can be improved, and the service life of the equipment can be extended. When the parameter value on the high-pressure side increases within the range greater than or equal to the second preset value and less than the third preset value, it proves that the upward trend of the high pressure is not effectively suppressed and there is a risk of breaking through the adjustment range. In this case, control the rotational speed of the outdoor fan to be immediately reduced to the lowest, and combine with the reduction of the compressor frequency to effectively reduce the system load, and as soon as possible slow down or suppress the upward trend of the high pressure to avoid frequent shutdown of the system.

[0045] Among them, the present invention does not limit the specific implementation manner of periodically reducing the rotational speed of the outdoor fan. For example, the outdoor fan has a total of 5 gears, the outdoor fan reduces 1 gear every 20 seconds, or the outdoor fan reduces 200 revolutions every 15 seconds. The value of the lowest rotational speed of the outdoor fan can also be adjusted. The lowest rotational speed of the outdoor fan can be determined based on the design specifications of the equipment itself. Usually, the lowest operating rotational speed will be given in the equipment manual or technical parameter table, or it can also be designed according to the energy efficiency and noise of the heat pump water system. Exemplarily, the lowest rotational speed of the outdoor fan can be 600 revolutions or 800 revolutions, and the highest rotational speed can be 1400 revolutions or 1600 revolutions.

[0046] As a possible implementation, the second interval of "greater than or equal to the second preset value and less than the third preset value" can be divided into a first sub-interval of "greater than or equal to the second preset value and less than the fourth preset value" and a second sub-interval of "greater than or equal to the fourth preset value and less than the third preset value". When the high-side parameter value increases within the first sub-interval, the frequency of the compressor is controlled to periodically decrease by a first preset amplitude. When the high-side parameter value increases within the second sub-interval, the frequency of the compressor is controlled to decrease by a second preset amplitude. After the frequency of the compressor decreases by the second preset amplitude, the frequency of the compressor is controlled to periodically decrease by the first preset amplitude. Wherein, the second preset amplitude is greater than the first preset amplitude. Possibly, when the high-side parameter value increases within the first sub-interval, the outdoor fan speed is controlled to decrease to the preset minimum speed. The present invention does not limit the specific value of the fourth preset value, as long as it is greater than the second preset value and less than the third preset value. In order to leave time for the high-pressure response, the fourth preset value is preferably located in the middle part between the second preset value and the third preset value. For example, when the high-side parameter value is the saturation temperature value, the first preset value is 55°C, the second preset value is 58°C, and the third preset value is 65°C, the fourth preset value can be 63°C. When the first preset value is 52°C, the second preset value is 56°C, and the third preset value is 63°C, the fourth preset value can be 60°C. When the high-side parameter value is the high-pressure value, the specific value of the fourth preset value can be the high-pressure value corresponding to the above values.

[0047] By dividing the reduction of the compressor frequency into two stages, that is, when the high-side parameter value increases within the first sub-interval, the frequency of the compressor is controlled to periodically decrease by the first preset amplitude, the frequency of the compressor can be moderately reduced, which is beneficial to the stable operation of the system. At the same time, reducing the outdoor fan speed to the lowest speed can effectively suppress the rising trend of the high pressure. When the high-side parameter value increases within the second sub-interval, the system high-pressure is still rising and is already close to the alarm value. Therefore, stronger control measures need to be taken. At this time, controlling the frequency of the compressor to decrease by the second preset amplitude in time, that is, reducing the frequency of the compressor by a larger amplitude, can significantly reduce the working load of the compressor in a shorter time and more quickly suppress the continuous increase of the high pressure, and the system can more effectively avoid the high pressure reaching the alarm value or entering a dangerous state. In order to avoid oscillations or instability caused by over-regulation, the system will continue to periodically decrease by the first preset amplitude after reducing by the second preset amplitude to maintain the balance of the system.

[0048] Among them, the present invention does not limit the specific implementation manner of periodically reducing the frequency of the compressor by the first preset amplitude. For example, the compressor frequency is reduced by 15% every 30s. Or the compressor frequency is reduced by 10% every 20s, etc. The specific period and amplitude can be set according to the response speed of the system, etc., to ensure system stability and effective suppression of the system high pressure. For the second preset amplitude, it is usually 30%-40%, for example, 40%, but it can also be adjusted according to the actual high pressure demand and system design. When selecting the second preset amplitude, the working efficiency of the compressor and the safety of the system can be considered. A larger amplitude (such as 40%) can quickly suppress the rapid rise of the high pressure, but too large an amplitude may cause the system to respond too quickly and affect stability. Therefore, this value needs to ensure effective control of the high pressure while ensuring the reliable operation of the system.

[0049] As a possible implementation manner, the control method of the present invention further includes: when the high-pressure side parameter value is greater than or equal to the second preset value and lasts for the first preset time, performing a compressor frequency update step: obtaining the outdoor ambient temperature; based on the outdoor ambient temperature, determining the maximum frequency of the compressor, and controlling the operating frequency of the compressor not to exceed the maximum frequency.

[0050] The present invention does not limit the specific value of the first preset time, which can be determined according to the actual operating conditions and control requirements of the system. For example, in some systems that are more sensitive to the change of high pressure and have higher control precision requirements, the first preset time can be set to a smaller value, such as 3 seconds to 5 seconds; while for some large-scale heat pump water systems with larger thermal inertia, the first preset time can be appropriately extended to 10 seconds to 15 seconds. The setting of the first preset time can give a certain buffer time at the initial stage when the system shows an abnormal high pressure trend, so as to more accurately judge whether the high pressure state is a short-term fluctuation or a continuous abnormality.

[0051] During the heating operation, the second heat exchanger on the outdoor side exchanges heat with the outdoor air, and the outdoor ambient temperature affects the evaporation pressure of the refrigerant. There is a close cooperative relationship between the frequency of the compressor and the evaporation pressure, and both have a significant impact on the high pressure of the system. Therefore, based on the outdoor ambient temperature, determining the maximum frequency of the compressor and then controlling the operating frequency of the compressor not to exceed the maximum frequency can prevent the high pressure of the system from rising sharply, prevent the high pressure protection from being frequently triggered resulting in system shutdown, and can optimize the energy efficiency ratio.

[0052] As a possible implementation, the higher the temperature range of the outdoor ambient temperature, the lower the corresponding maximum frequency of the compressor. If the outdoor ambient temperature is relatively high, the evaporation pressure is already at a relatively high level. At this time, if the compressor frequency is too high, it will cause a significant increase in the refrigerant circulation flow rate and a sharp rise in the compressor discharge volume, thereby rapidly increasing the high-pressure of the system and exceeding the safe range that the system can withstand, easily triggering serious problems such as the activation of the high-pressure protection device and causing the system to shut down. Therefore, the higher the temperature range of the outdoor ambient temperature in the present invention, the lower the corresponding maximum frequency of the compressor, which can effectively prevent the occurrence of the above problems. On the contrary, in a low-temperature environment, only by matching a relatively low evaporation pressure with a not-too-low compressor frequency can the high-pressure of the system be maintained within a reasonable range, ensuring the stable, efficient and safe operation of the heat pump water system.

[0053] For example, when the outdoor ambient temperature > 10°C, control the operating frequency of the compressor not to exceed 60% of the preset maximum frequency. When 0°C < outdoor ambient temperature ≤ 10°C, control the operating frequency of the compressor not to exceed 80% of the preset maximum frequency. When -7°C < outdoor ambient temperature ≤ 0°C, control the operating frequency of the compressor not to exceed 90% of the preset maximum frequency. When the outdoor ambient temperature < -7°C, control the operating frequency of the compressor not to exceed 100% of the preset maximum frequency. It should be noted that the above values of the maximum frequency of the compressor under different outdoor ambient temperatures are not fixed and can be flexibly adjusted according to various factors.

[0054] As a possible implementation, when the high-pressure side parameter value is less than or equal to the difference between the second preset value and the preset positive buffer value, the compressor frequency update step is exited. Thereby, it can effectively avoid that when the high-pressure pressure returns to normal or is at a low level, the system still over-limits the operating frequency of the compressor, resulting in an unnecessary reduction in the heating efficiency of the system. Among them, the compressor frequency update step is exited only when the high-pressure side parameter value is less than or equal to the difference between the second preset value and the preset positive buffer value, which can provide a reasonable transition interval for the control of the system high-pressure side parameter value. When the high-pressure side parameter value is close to the second preset value, if there is no positive buffer value, the system may immediately exit the compressor frequency update step when the high-pressure side parameter value is just equal to the second preset value, such as causing the compressor frequency to rise rapidly, and then the high-pressure side parameter value quickly rises back to the dangerous area, causing the system to frequently switch between limiting and releasing the limit on the compressor frequency, which not only affects the stability of the system operation, but also increases the wear and energy consumption of the equipment. The existence of the positive buffer value means that the compressor frequency update step will be exited only when the high-pressure side parameter value is lower than the second preset value to a certain extent, such as when the difference is 56°C (58°C-2°C). This ensures that the system will return to normal after the high-pressure pressure is stably reduced to a safe range, effectively preventing repeated fluctuations in the high-pressure side pressure and ensuring the stable and reliable operation of the heat pump water system. Generally speaking, the positive buffer value ranges from 1°C to 5°C, such as 2°C.

[0055] Furthermore, the compressor frequency update step is exited only when the high-pressure side parameter value is less than or equal to the difference between the second preset value and the preset positive buffer value, and lasts for the third preset time. To ensure that the high-pressure side parameter continuously and stably meets the above interval conditions for a period of time, the operating state of the heat pump water system is relatively stable, thereby avoiding premature exit from the update step due to misjudgment, and ensuring reliable operation and precise control of the entire system. Among them, the present invention does not limit the specific value of the third preset time, which can be adjusted according to actual conditions or experiments. For example, it can be 30 seconds or 20 seconds, etc.

[0056] In summary, when the high-pressure side parameter value is greater than or equal to the second preset value and lasts for the first preset time, the compressor frequency update step is executed according to the outdoor ambient temperature to determine the maximum frequency of the compressor. Combined with the control of the outdoor fan speed and the compressor frequency, the three can jointly stabilize the system high-pressure pressure and avoid failures caused by high-pressure abnormalities; and can optimize the energy efficiency ratio to ensure stable and efficient operation of the system.

[0057] As a possible implementation, the control method of the present invention further includes: when the high-pressure side parameter value is greater than the maximum value within the adjustment range and lasts for a second preset time, controlling the heat pump water system to shut down. Further, an alarm message is also sent. When the high-pressure side parameter value exceeds the maximum value of the adjustment range for a long time, it indicates that the heat pump water system is in a serious high-pressure abnormal state. Continuing to operate may cause excessive pressure on each component of the system, leading to serious faults such as compressor damage and pipeline rupture, and even causing safety accidents. By shutting down in time, irreversible damage to the heat pump water system due to excessive high-pressure can be effectively avoided, the maintenance cost and risk can be reduced, and the service life of the system can be extended. Sending an alarm message can promptly remind the maintenance personnel of the system abnormality so that corresponding countermeasures can be taken in time. Among them, the present invention does not limit the specific value of the second preset time. For example, if the heat pump water system is more sensitive to high-pressure abnormalities, the value of the second preset time can be smaller, such as 3 seconds to 5 seconds, for example, 3 seconds; if the change of the high-pressure side parameter is relatively slow, the second preset time can be appropriately extended to 8 seconds to 12 seconds.

[0058] Possibly, when the high-pressure side parameter value is less than the minimum value within the adjustment range, when the high-pressure side parameter value no longer rises within the adjustment range, or when it is greater than the maximum value within the adjustment range but the duration is less than 3 seconds, control the normal operation of the compressor frequency and the outdoor fan speed. For example, the compressor can operate based on the standard frequency curve initially set in the heating mode; or it can be dynamically adjusted based on factors such as the temperature difference between the outdoor environment temperature and the water temperature set by the user. If the temperature difference is large, the compressor frequency is increased, and if the temperature difference is small, the compressor frequency can be decreased. The outdoor fan speed can operate based on the preset standard speed, or adjust the outdoor fan speed based on factors such as the high or low temperature of the outdoor coil.

[0059] As a possible implementation, as Figure 3 shown, the control method of the air source heat pump water system of the present invention includes the following steps:

[0060] Step S301: In the heating mode, obtain the saturation temperature Pd_t corresponding to the high-pressure.

[0061] Step S302: Determine whether Pd_t is rising within the range of (55°C - 65°C)? If so, execute Step S303; if not, execute Step S310.

[0062] Step S303: Determine whether Pd_t ≥ 58°C holds? If so, execute Step S304; if not, execute Step S308.

[0063] Step S304: Determine whether it lasts for 5 seconds? If so, execute Step S309; if not, execute Step S305.

[0064] Step S305: Determine whether Pd_t≥63°C holds. If so, execute Step S306; if not, execute Step S307.

[0065] Step S306: Control the frequency of the compressor to decrease by 40%. After the frequency of the compressor decreases by 40%, control the frequency of the compressor to decrease by 15% every 30 s; control the rotational speed of the outdoor fan to decrease to a preset minimum rotational speed.

[0066] Step S307: Control the frequency of the compressor to decrease by 15% every 30 s, and control the rotational speed of the outdoor fan to decrease to a preset minimum rotational speed.

[0067] Step S308: Control the frequency of the compressor to remain unchanged or decrease, and control the rotational speed of the outdoor fan to decrease by one gear every 20 s.

[0068] Step S309: Determine the maximum frequency of the compressor based on the outdoor ambient temperature, and control the operating frequency of the compressor not to exceed the maximum frequency, and then execute Step S305.

[0069] Step S310: Determine whether Pd_t≥65°C holds. If so, execute Step S311; if not, execute Step S313.

[0070] Step S311: Determine whether it lasts for 3 s. If so, execute Step S312; if not, execute Step S313.

[0071] Step S312: Control the heat pump water system to stop operating, and send an alarm message.

[0072] Step S313: The compressor frequency and the rotational speed of the outdoor fan operate normally.

[0073] Those skilled in the art can understand that the above air source heat pump water system includes some other well-known structures, such as a processor, a controller, a memory, etc. Among them, the memory includes but is not limited to a random access memory, a flash memory, a read-only memory, a programmable read-only memory, a volatile memory, a non-volatile memory, a serial memory, a parallel memory, or a register, etc. The processor includes but is not limited to a CPLD / FPGA, a DSP, an ARM processor, a MIPS processor, etc. For the purpose of not unnecessarily obscuring the embodiments of the present disclosure, these well-known structures are not shown in the drawings. The memory is adapted to store multiple program codes, and the program codes are adapted to be loaded and run by the processor to execute the control method of the heat pump water system.

[0074] So far, the technical solution of the present invention has been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A control method for an air source heat pump water system, characterized in that The control method includes: In the heating mode, obtain the high-pressure side parameter value; When the high-pressure side parameter value rises within a preset adjustment range, control the frequency of the compressor to decrease or remain unchanged, and control the rotational speed of the outdoor fan to decrease; Wherein, the high-pressure side parameter is the high-pressure value or the saturation temperature value corresponding to the high-pressure value.

2. The control method of the air source heat pump water system according to claim 1, characterized in that The step of "when the high-pressure side parameter value rises within a preset adjustment range, control the rotational speed of the outdoor fan to decrease" further includes: When the high-pressure side parameter value rises within the range greater than the first preset value and less than the second preset value, control the rotational speed of the outdoor fan to decrease periodically; and / or When the high-pressure side parameter value rises within the range greater than or equal to the second preset value and less than the third preset value, control the rotational speed of the outdoor fan to decrease to a preset minimum rotational speed.

3. The control method of the air source heat pump water system according to claim 1 or 2, characterized in that The step of "when the high-pressure side parameter value rises within a preset adjustment range, control the frequency of the compressor to decrease or remain unchanged" further includes: When the high-pressure side parameter value rises within the range greater than the first preset value and less than the second preset value, control the frequency of the compressor to decrease or remain unchanged; When the high-pressure side parameter value rises within the range greater than or equal to the second preset value and less than the third preset value, control the frequency of the compressor to decrease.

4. The control method of the air source heat pump water system according to claim 3, characterized in that The step of "when the high-pressure side parameter value rises within the range greater than or equal to the second preset value and less than the third preset value, control the frequency of the compressor to decrease" further includes: When the high-pressure side parameter value rises within the range greater than or equal to the second preset value and less than the fourth preset value, control the frequency of the compressor to decrease periodically by a first preset amplitude; when the high-pressure side parameter value rises within the range greater than or equal to the fourth preset value and less than the third preset value, control the frequency of the compressor to decrease by a second preset amplitude; after the frequency of the compressor decreases by the second preset amplitude, control the frequency of the compressor to decrease periodically by the first preset amplitude; Wherein, the second preset amplitude is greater than the first preset amplitude.

5. The control method of the air source heat pump water system according to claim 3, characterized in that The control method further includes: When the high-pressure side parameter value is greater than or equal to the second preset value and lasts for a first preset time, execute the compressor frequency update step: Obtain the outdoor ambient temperature; Based on the outdoor ambient temperature, determine the maximum frequency of the compressor, and control the operating frequency of the compressor not to exceed the maximum frequency.

6. The control method of the air source heat pump water system according to claim 5, characterized in that The higher the temperature range where the outdoor ambient temperature is located, the lower the corresponding maximum frequency of the compressor.

7. The control method of the air source heat pump water system according to claim 5, characterized in that The control method further includes: When the high - voltage side parameter value is less than or equal to the difference between the second preset value and the preset positive buffer value, exit the compressor frequency update step.

8. The control method of the air - source heat pump water system according to claim 1, characterized in that: The control method further includes: When the high - voltage side parameter value is greater than the maximum value within the adjustment range and lasts for a second preset time, control the heat pump water system to stop.

9. The control method of the air - source heat pump water system according to claim 8, characterized in that: The control method further includes: When the high - voltage side parameter value is greater than the maximum value within the adjustment range and lasts for a second preset time, send an alarm message.

10. An air source heat pump water system, characterized in that, Comprising: A processor; A memory, the memory is adapted to store multiple program codes, and the program codes are adapted to be loaded and run by the processor to execute the control method of the air - source heat pump water system according to any one of claims 1 to 9.

Images