Control method of heat pump unit

Abstract

The invention relates to the technical field of heat pump units, particularly provides a control method of a heat pump unit, and aims to solve the problem that the heat pump unit has a frost crack risk due to limitation of single-point detection. In order to achieve the purpose, the control method of the heat pump unit comprises the steps that when a water flow switch is in an on state, whether the heat pump unit meets the anti-freezing mode condition or not is judged, and if yes, the heat pump unit is controlled to execute the anti-freezing mode. The condition that the water inlet temperature is smaller than the preset water inlet temperature and / or the temperature change rate of the water inlet temperature before and after the set time is larger than the preset change rate serves as the condition for triggering the anti-freezing mode, the frost crack risk of the unit can be judged more accurately, the safety and reliability of the heat pump unit are improved, and the anti-freezing effect is improved. The limitation that whether the anti-freezing mode condition is met or not is judged only depending on a single water temperature detection point is overcome, and the problem that a unit has the frost crack risk due to insufficient single-point detection is solved.

Description

Technical Field

[0001] The present invention relates to the field of heat pump units, and specifically provides a control method for a heat pump unit. Background Art

[0002] A heat pump unit is an energy-saving device that uses high-level energy to make heat flow from a low-level heat source (such as air, water, etc.) to a high-level heat source. It can effectively utilize low-grade heat energy that is difficult to apply and has the beneficial effect of energy conservation, so it is widely used in production and life. However, due to the characteristic that the heat pump unit uses water as a heat transfer medium, when it operates in winter, especially when the water temperature in the water circulation loop is too low, there is a risk of freezing and cracking of the unit.

[0003] Currently, to solve the above problems, it is usually necessary to detect the inlet water temperature of the water circulation loop and judge whether there is a risk of freezing and cracking of the unit according to the inlet water temperature. However, the existing anti-freezing solutions usually judge based on the water temperature at a certain point. Although this single-point detection method is simple, due to the uneven distribution of water temperature in the loop, single-point detection may not be able to capture potential low-temperature points. When these undetected low-temperature points reach the anti-freezing conditions, the unit may not be able to respond in time, resulting in problems such as freezing and cracking of the unit.

[0004] Therefore, a new technical solution is needed in this field to solve the above problems. Summary of the Invention

[0005] In order to solve at least one problem in the prior art, that is, to solve the problem that the heat pump unit has a risk of freezing and cracking due to the limitation of single-point detection, the present application provides a control method for a heat pump unit. The heat pump unit includes a water circulation loop, and a water flow switch is arranged on the water circulation loop. The control method includes:

[0006] When the water flow switch is in a conducting state, judge whether the heat pump unit meets the anti-freezing mode conditions;

[0007] When the anti-freezing mode conditions are met, control the heat pump unit to execute the anti-freezing mode;

[0008] Among them, the anti-freezing mode conditions include at least one of the following conditions:

[0009] The inlet water temperature of the water circulation loop is less than the preset inlet water temperature;

[0010] The temperature change rate of the inlet water temperature of the water circulation loop before and after the first set time is greater than the preset change rate.

[0011] In a preferred technical solution of the above control method, the step of "controlling the heat pump unit to execute the anti-freezing mode" further includes:

[0012] Obtain the outlet water temperature of the water circulation loop;

[0013] Calculate the difference between the outlet water temperature and the inlet water temperature;

[0014] Compare the difference with a preset difference;

[0015] Based on the comparison result, determine the anti-freezing mode of the heat pump unit;

[0016] Control the heat pump unit to execute the corresponding anti-freezing mode.

[0017] In a preferred technical solution of the above control method, when a water pump is provided on the water circulation loop, the anti-freezing mode includes a first mode and a second mode. The first mode is that the water pump operates at a first operating frequency, and the second mode is that the water pump operates at a second operating frequency;

[0018] Wherein, the first operating frequency is less than the operating frequency of the water pump when the heat pump unit is in the normal mode, and the second operating frequency is greater than the operating frequency of the water pump when the heat pump unit is in the normal mode.

[0019] In a preferred technical solution of the above control method, the step of "based on the comparison result, determine the anti-freezing mode of the heat pump unit" further includes:

[0020] When the difference is greater than the preset difference, control the heat pump unit to operate according to the first mode;

[0021] When the difference is less than or equal to the preset difference and greater than 0°C, control the heat pump unit to operate according to the second mode.

[0022] In a preferred technical solution of the above control method, the control method further includes:

[0023] When the difference is less than or equal to 0°C, control the water pump to stop running.

[0024] In a preferred technical solution of the above control method, when "control the water pump to stop running" or after that, it further includes:

[0025] Send a reminder to remind the user to repair the water pump.

[0026] In a preferred technical solution of the above control method, the control method further includes:

[0027] When the water flow switch is in the off state, obtain the running current and no-load current of the water pump

[0028] Compare the running current and the no-load current;

[0029] Based on the comparison result, determine whether there is water flow in the water circulation loop;

[0030] When there is water flow in the water pump, determine whether the heat pump unit meets the anti-freezing mode condition.

[0031] In the preferred technical solution of the above control method, the step of "based on the comparison result, determine whether there is water flow in the water pump" further includes:

[0032] When the operating current is greater than the no-load current, determine that there is water flow in the water circulation loop.

[0033] In the preferred technical solution of the above control method, before the step of "determine whether the heat pump unit meets the anti-freezing mode condition", it further includes:

[0034] Obtain the ambient temperature;

[0035] Compare the ambient temperature with the preset ambient temperature;

[0036] When the ambient temperature is less than the preset ambient temperature, determine whether the heat pump unit meets the anti-freezing mode condition.

[0037] In the preferred technical solution of the above control method, after the step of "control the heat pump unit to execute the anti-freezing mode", it further includes:

[0038] Every second set time, determine whether the heat pump unit meets the condition for exiting the anti-freezing mode;

[0039] When the heat pump unit meets the condition for exiting the anti-freezing mode, control the heat pump unit to exit the anti-freezing mode;

[0040] Among them, the conditions for exiting the anti-freezing mode include the following two conditions:

[0041] The inlet water temperature is greater than or equal to the preset inlet water temperature;

[0042] The temperature change rate of the inlet water temperature within the third set time is less than or equal to the preset change rate.

[0043] Those skilled in the art can understand that for the control method of the heat pump unit in this application, by using the inlet water temperature being less than the preset inlet water temperature, and / or the temperature change rate of the inlet water temperature before and after the set time being greater than the preset change rate as the conditions for triggering the anti-freezing mode, it can help to more accurately determine the risk of freezing and cracking faced by the unit, improve the safety and reliability of the heat pump unit, overcome the limitation of relying only on a single water temperature detection point to determine whether the anti-freezing mode condition is met, and solve the problem of freezing and cracking of the unit caused by insufficient single-point detection.

[0044] Furthermore, when the unit meets the anti-freezing mode conditions, by determining the anti-freezing mode of the unit according to the magnitude of the difference value and the preset difference value, and controlling the unit to execute the corresponding anti-freezing mode, the anti-freezing strategy can be optimized, and the safety, reliability and stability of the unit can be improved.

[0045] Furthermore, by setting the anti-freezing mode to the first mode and the second mode, and the adjustment methods of the pump operation frequency are different under different modes, the anti-freezing mode of the unit becomes more reasonable.

[0046] Furthermore, by comparing the difference value with the preset difference value to determine the anti-freezing mode of the unit, the unit can operate according to the determined anti-freezing mode, realizing the adaptive adjustment of the anti-freezing mode of the unit according to the inlet and outlet water temperatures.

[0047] Furthermore, when the inlet water temperature is greater than or equal to the outlet water temperature, by controlling the pump to stop running, it is convenient to repair the pump and improve the safety of the pump.

[0048] Furthermore, when the water flow switch is in the off state, by comparing the operating current and no-load current of the pump, it is possible to judge whether there is water flow in the circuit, thereby improving the accuracy of the detection result of the water flow state in the water circulation circuit, reducing the misjudgment of the water flow in the water circulation circuit, and improving the reliability of the unit.

[0049] Furthermore, when the ambient temperature is less than the preset ambient temperature, by judging whether the heat pump unit meets the anti-freezing mode conditions, the accuracy of judging the anti-freezing mode conditions can be improved, and the stability and reliability of the unit can be enhanced.

[0050] Furthermore, by accurately judging the anti-freezing situation of the unit according to the magnitude of the temperature change rate of the inlet water temperature before and after the set time and the preset change rate, and timely exiting the anti-freezing mode when the temperature change rate is less than or equal to the preset change rate, it is possible to avoid affecting the comfort of users due to long-term operation of the anti-freezing mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings, in which:

[0052] Figure 1 is the flowchart of the control method of the heat pump unit of the present application;

[0053] Figure 2 is the system diagram of the heat pump unit of the present application;

[0054] Figure 3 is the logic diagram of a possible implementation manner of the control method of the heat pump unit of the present application.

[0055] Description of the reference numerals:

[0056] 1. Water circulation loop; 2. Target flow switch; 3. Water pump; 4. Indoor heat exchanger. Detailed implementation manners

[0057] The preferred implementation manners of the present application 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 application and are not intended to limit the protection scope of the present application.

[0058] It should be noted that in the description of the present application, the terms indicating directions or positional relationships such as "upper", "lower", "inner", "bottom", "end", etc. are based on the directions or positional relationships shown in the drawings. This is only for convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present application.

[0059] In addition, it should also be noted that in the description of the present application, unless otherwise clearly specified and limited, the terms "set", "connected", "communicated" 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, a direct connection, or an indirect connection through an intermediate medium, and it can be the communication inside two elements. For those skilled in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0060] First, in combination with Figure 1-2 , the control method of the heat pump unit of the present application will be introduced. Among them, Figure 1 is the flowchart of the control method of the heat pump unit of the present application. Figure 2 is the system diagram of the heat pump unit of the present application.

[0061] As Figure 1 shown, the heat pump unit includes a water circulation loop 1, and a water flow switch is provided on the water circulation loop 1. Among them, the on-off state of the water flow switch can judge the water flow rate in the water circulation loop 1, that is, when there is water flow in the water circulation loop 1, the water flow switch is in the on state, and when there is no water flow in the water circulation loop 1, the water flow switch is in the off state. However, when the water flow switch is in the on state, that is, when there is water flow in the water circulation loop 1, there is a problem of uneven temperature distribution of the water flow, so that it is impossible to accurately judge whether the unit meets the anti-freezing mode condition only by detecting the water temperature at a single point, resulting in the problem that the unit still has a risk of freezing and cracking.

[0062] Among them, the present application does not limit the specific type of the water flow switch, as long as the water flow switch can detect the water flow rate in the water circulation loop 1. For example, the water flow switch can be a target flow switch 2.

[0063] As Figure 2As shown, to solve the above problems, the control method of the heat pump unit of the present application includes:

[0064] S101. When the water flow switch is in the conducting state, determine whether the heat pump unit meets the anti-freezing mode condition. For example, the water flow switch can be a target flow switch 2. When the target flow switch 2 is in the conducting state, it indicates that there is water flow in the water circulation loop 1. In a low-temperature environment, the water circulation loop is prone to icing problems. Therefore, when there is water flow, a temperature sensor can be configured on the water inlet side of the water circulation loop 1, that is, on the water inlet side of the indoor heat exchanger 4. Through the temperature sensor, the water inlet temperature of the water circulation loop 1 can be detected, and whether the anti-freezing mode condition is met can be determined according to the magnitude of the water inlet temperature.

[0065] S102. When the anti-freezing mode condition is met, control the heat pump unit to execute the anti-freezing mode. For example, when the unit meets the anti-freezing mode condition, to reduce the risk of the unit being frozen and cracked, it is necessary to control the heat pump unit to execute the anti-freezing mode to ensure the stable operation of the unit.

[0066] Among them, the anti-freezing mode condition includes at least one of the following conditions:

[0067] 1) The water inlet temperature of the water circulation loop 1 is less than the preset water inlet temperature. For example, a temperature sensor can be configured on the water inlet side of the water circulation loop 1. Through the temperature sensor, the water inlet temperature T ewi1 of the water circulation loop 1 can be obtained. After obtaining the water inlet temperature T ewi1 of the water circulation loop 1, by comparing whether the difference between the water inlet temperature T ewi1 and the preset water inlet temperature T ewi1 ` is greater than 0, or by comparing whether the ratio between the two is greater than 1, the magnitudes of the two can be compared to determine whether the anti-freezing mode condition is met. Therefore, when T ewi1 < T ewi1 `, it can be used to determine that the heat pump unit meets the anti-freezing mode condition.

[0068] 2) The temperature change rate of the water inlet temperature of the circulation loop 1 before and after the first set time is greater than the preset change rate. For example, to avoid the problem that the unit still has a risk of being frozen and cracked because a single water temperature detection point cannot accurately determine whether the unit meets the anti-freezing mode condition, it is necessary to obtain the water inlet temperatures T ewi1 and T ewi2 before and after the unit operates for the first set time. By calculating the difference between T ewi1 and T ewi2The difference is obtained, and this difference is compared with the first set time to obtain the temperature change rate K1 of the inlet water temperature before and after the first set time. When K1 > K1`, it indicates that the water temperature distribution of the water flow is uneven and the temperature fluctuation is relatively large. Since the antifreeze cracking problem only exists when the unit operates in winter, the application environment of the entire control method is winter. Without considering the magnitude of the inlet water temperature and the preset inlet water temperature, using K1 > K1` can also be used to determine that the heat pump unit meets the conditions for the antifreeze mode.

[0069] By using the inlet water temperature being less than the preset inlet water temperature, and / or the temperature change rate value of the inlet water temperature before and after the set time being greater than the preset change rate as the condition for triggering the antifreeze mode, this application can help more accurately determine the frost cracking risk faced by the unit, improve the safety and reliability of the heat pump unit, overcome the limitation of relying only on a single water temperature detection point to determine whether the antifreeze mode conditions are met, and solve the problem of the unit having a frost cracking risk due to insufficient single-point detection.

[0070] It should be noted that this application can use only the inlet water temperature of the water circulation loop 1 being less than the preset inlet water temperature as the antifreeze mode condition, or use the temperature change rate value of the inlet water temperature before and after the first set time being greater than the preset change rate as the antifreeze mode condition, or use both the inlet water temperature of the water circulation loop 1 being less than the preset inlet water temperature and the temperature change rate of the inlet water temperature before and after the first set time being greater than the preset change rate as the antifreeze mode condition. Additionally, the unit mentioned in this application refers to the heat pump unit.

[0071] The preferred implementation manners of the control method of the heat pump unit of this application are introduced below.

[0072] In one implementation manner, before the step of "judging whether the heat pump unit meets the antifreeze mode conditions", it further includes:

[0073] Obtain the ambient temperature;

[0074] Compare the magnitude of the ambient temperature and the preset ambient temperature;

[0075] When the ambient temperature is less than the preset ambient temperature, judge whether the heat pump unit meets the antifreeze mode conditions.

[0076] It should be noted that when the ambient temperature is too low, it is easy to increase the frost cracking risk faced by the unit. Therefore, before judging whether the unit meets the antifreeze mode conditions, the ambient temperature can be compared with the preset ambient temperature, and when the ambient temperature is less than the preset ambient temperature, judge whether the unit meets the antifreeze mode conditions.

[0077] For example, taking the ambient temperature as Ta and the preset ambient temperature Ta` as 0 °C for illustration. When Ta < 0 °C, it indicates that the ambient temperature is relatively low, and at this time, the unit faces a relatively high risk of freezing and cracking. To further determine whether the unit needs to execute the anti-freezing mode, it is also necessary to determine whether the unit meets the anti-freezing mode conditions, such as the inlet water temperature and / or the change rate of the inlet water temperature to determine whether the unit meets the anti-freezing mode conditions. When Ta ≥ 0 °C, it indicates that the ambient temperature is relatively high, and at this time, the unit faces a relatively low risk of freezing and cracking, and there is no need to judge the anti-freezing mode conditions, and the normal working mode of the unit can be maintained.

[0078] In one implementation manner, the step of "controlling the heat pump unit to execute the anti-freezing mode" further includes:

[0079] Obtain the outlet water temperature of the water circulation loop 1;

[0080] Calculate the difference between the outlet water temperature and the inlet water temperature;

[0081] Compare the size of the difference with the preset difference;

[0082] Based on the comparison result, determine the anti-freezing mode of the heat pump unit;

[0083] Control the heat pump unit to execute the corresponding anti-freezing mode.

[0084] Among them, the outlet water temperature T of the water circulation loop 1 ewo , refers to Figure 1 the temperature on the outlet side of the indoor heat exchanger 4 in . When the unit meets the anti-freezing mode conditions, by calculating the difference ΔT between the outlet water temperature and the inlet water temperature, the heating capacity of the unit can be judged. When the difference ΔT is larger, it indicates that the heating capacity of the unit is larger, and when the difference ΔT is smaller, it indicates that the heating capacity of the unit is smaller. According to the heating capacity of the unit, execute the corresponding anti-freezing mode to ensure that the unit can improve the comfort of users while operating stably.

[0085] Furthermore, when a water pump 3 is provided on the water circulation loop 1, the anti-freezing mode includes a first mode and a second mode. The first mode is that the water pump 3 operates at a first operating frequency, and the second mode is that the water pump 3 operates at a second operating frequency;

[0086] The anti-freezing mode includes a first mode and a second mode. When these two modes are operating, the operating frequency of the water pump 3 is different. In the first mode, the operating frequency of the water pump 3 is low, and in the second mode, the operating frequency of the water pump 3 is high. This is related to the heating capacity of the unit. When the heating capacity of the unit is relatively high, the water pump 3 can achieve the purpose of anti-freezing by operating at the first operating frequency. When the heating capacity of the unit is relatively high, the water pump 3 needs to operate at the second operating frequency to achieve the purpose of anti-freezing. Among them, the first operating frequency is less than the operating frequency of the water pump 3 when the unit is in the normal mode, and the second operating frequency is greater than the operating frequency of the water pump 3 when the unit is in the normal mode. Therefore, the first operating frequency is less than the second operating frequency. In addition, the water pump 3 can be arranged at the inlet side of the water circulation loop 1, that is, the inlet side of the indoor heat exchanger 4, as shown in Figure 2 It is shown and arranged at the inlet side of the water circulation loop 1, that is, the inlet side of the indoor heat exchanger 4, so that the water flow can enter the indoor heat exchanger 4 through the water pump 3.

[0087] For example, in one embodiment, the step of "determining the anti-freezing mode of the heat pump unit based on the comparison result" further includes:

[0088] When the difference is greater than the preset difference, control the heat pump unit to operate according to the first mode;

[0089] When the difference is less than or equal to the preset difference and greater than or equal to 0 °C, control the heat pump unit to operate according to the second mode.

[0090] For example, taking the difference as ΔT and the preset difference ΔT` as 10 °C for illustration. When ΔT > 10 °C, it indicates that the heating capacity of the unit is high. Reducing the operating frequency of the heat pump will not cause the risk of the unit being frozen and cracked. Therefore, the unit can be controlled to operate according to the first mode. When 0 °C < ΔT ≤ 10 °C, it indicates that the heating capacity of the unit is low. Reducing the operating frequency of the heat pump will not cause the risk of the unit being frozen and cracked. Therefore, the unit can be controlled to operate according to the second mode.

[0091] In one embodiment, the control method further includes:

[0092] When the difference is less than or equal to 0 °C, control the water pump 3 to stop operating.

[0093] For example, taking the outlet water temperature as T ewo , and the difference as ΔT for illustration. When ΔT ≤ 0 °C, it indicates that the inlet water temperature is greater than or equal to the outlet water temperature T ewo . Since the unit is in the heating mode, according to the heating working principle of the unit, the inlet water temperature must be lower than the outlet water temperature T ewo . If the inlet water temperature is higher than the outlet water temperature T ewo , then there is an abnormality in the water pump 3. Therefore, it is necessary to control the water pump 3 to stop operating and further check and diagnose the water pump 3.

[0094] Further, simultaneously with or after "controlling the water pump 3 to stop running", it further includes:

[0095] Sending a reminder to remind of the maintenance of the water pump 3.

[0096] To facilitate reminding the user to timely maintain the water pump 3, a reminder can be sent simultaneously with or after controlling the water pump 3 to stop running, so as to avoid more serious consequences caused by failure to handle in time.

[0097] In one embodiment, the control method further includes:

[0098] When the water flow switch is in the off state, obtaining the operating current and no-load current of the water pump 3

[0099] Comparing the magnitudes of the operating current and the no-load current;

[0100] Based on the comparison result, determining whether there is water flow in the water circulation loop 1;

[0101] When there is water flow in the water pump 3, determining whether the heat pump unit meets the anti-freezing mode condition.

[0102] It should be noted that the water flow switch has limitations in some cases. Especially when the water flow rate in the water circulation loop 1 is relatively small, the water flow switch cannot detect the water flow, and at this time the water flow switch is in the off state. To accurately determine whether there is water flow in the water circulation loop 1, it is necessary to rely on the operating current of the water pump 3 as the judgment basis. Specifically, when the water pump 3 is in the no-load state, since there is no water flow passing through, its load is relatively light, so the current value will remain at a relatively low level. And when the water pump 3 starts to work and there is water flow passing through, the water pump 3 needs to overcome the pipeline resistance, lift the water level, etc., thereby causing the current value to rise. Therefore, by judging the magnitude relationship between the actual current and the no-load current, it can be determined whether there is water flow in the water circulation loop 1. When there is water flow in the water circulation loop 1, the steps when the water flow switch is in the on state can be followed.

[0103] Specifically, the step of "based on the comparison result, determining whether there is water flow in the water pump 3" further includes:

[0104] When the operating current is greater than the no-load current, determining that there is water flow in the water circulation loop 1.

[0105] For example, taking the operating current as I and the no-load current as I 空载Taking the current I as 1A and the water flow switch as the target flow switch 2 for illustration. When I > 0.1A, it indicates that there is water flow in the water circulation loop 1. When there is water flow in the water circulation loop 1, the steps where the target flow switch 2 is in the conducting state can be followed. When I ≤ 0.1A, it indicates that no water flows through the water pump 3, so there is no water flow in the water circulation loop 1 and anti-freezing is not required.

[0106] In one implementation, after the step of "controlling the heat pump unit to execute the anti-freezing mode", it further includes:

[0107] Every second set time, determine whether the heat pump unit meets the condition for exiting the anti-freezing mode;

[0108] When the heat pump unit meets the condition for exiting the anti-freezing mode, control the heat pump unit to exit the anti-freezing mode;

[0109] Among them, the condition for exiting the anti-freezing mode includes the following two conditions:

[0110] The inlet water temperature is greater than or equal to the preset inlet water temperature;

[0111] The temperature change rate of the inlet water temperature before and after the third set time is less than or equal to the preset change rate.

[0112] Among them, the third set time can be the same as the first set time or different from the first set time. In addition, in order to accurately determine whether the unit meets the condition for exiting the anti-freezing mode, it is necessary to simultaneously use the inlet water temperature being greater than or equal to the preset inlet water temperature and the temperature change rate of the inlet water temperature before and after the set time being less than or equal to the preset change rate as the conditions for exiting the anti-freezing mode.

[0113] For example, taking the anti-freezing mode as the first mode, the second set time as 10 min, the third set time as 5 min, the preset inlet water temperature as 0 °C, and the preset change rate K` as 1 for illustration. After controlling the unit to execute the first mode for 10 min, it is necessary to obtain the inlet water temperature T again ewi3 , and compare this inlet water temperature T ewi3 with the preset inlet water temperature T ewi `. When T ewi3 > 0 °C, it indicates that the water flow temperature on the inlet side of the water circulation loop 1 is relatively high. To avoid the limitation of single-point detection, after controlling the unit to execute the first mode for 5 min, obtain the inlet water temperature T again ewi4 , calculate the difference K2 of the inlet water temperature before and after the third set time, and compare this difference K2 with the inlet water temperature before the first set time to obtain the temperature change rate K`. When K2 ≤ K`, the unit meets the condition for exiting the anti-freezing mode, and then control the unit to operate in the normal mode.

[0114] The following combines with Figure 3, a possible operation process of the control method of the heat pump unit of the present application will be briefly described. Figure 3 It is a logic diagram of a possible implementation manner of the control method of the heat pump unit of the present application.

[0115] S201. Obtain the operating state of the target flow switch 2, and then execute S202.

[0116] S202. Determine whether the target flow switch 2 is in the conducting state? If so, execute S203; if not, execute S221.

[0117] S203. Obtain the ambient temperature Ta, and then execute S204.

[0118] S204. Determine whether Ta < 0°C holds? If it holds, execute S205; otherwise, execute S203.

[0119] S205. Obtain the inlet water temperature T of the water circulation loop 1 ewi1 , and then execute S206.

[0120] S206. Determine whether T ewi1 < 0°C holds? If it holds, execute S207; otherwise, execute S213.

[0121] S207. Obtain the outlet water temperature T of the water circulation loop 1 ewo , and then execute S208.

[0122] S208. Calculate the difference ΔT between the outlet water temperature T ewo and the inlet water temperature, and then execute S209.

[0123] S209. Determine whether ΔT > 10°C holds? If it holds, execute S210; if 0°C < ΔT ≤ 10°C, execute S211; if ΔT ≤ 0°C, execute S212.

[0124] S210. Reduce the operating frequency of the water pump 3 and operate at the first operating frequency, and then execute S216.

[0125] S211. Increase the operating frequency of the water pump 3 and operate at the first operating frequency, and then execute S216.

[0126] S212. Control the water pump 3 to stop running and issue a reminder.

[0127] S213. After running for 5 minutes, obtain the inlet water temperature T again ewi2 , and then execute S214.

[0128] S214. Calculate the temperature change rate K1 of the inlet water temperature before and after the first set time, and then execute S215.

[0129] S215. Determine whether K1 > 1 holds. If it holds, execute S207; otherwise, execute S203.

[0130] S216. Every 10 minutes, obtain the inlet water temperature T ewi3 , and then execute S217.

[0131] S217. After running for 5 minutes, obtain the inlet water temperature T again ewi4 , and then execute S218.

[0132] S218. Calculate the temperature change rate K2 of the inlet water temperature before and after the third set time, and then execute S219.

[0133] S219. Determine whether K2 ≤ 1 holds. If it holds, execute S220; otherwise, execute S216.

[0134] S220. Control the water pump 3 to operate at the operating frequency in the normal mode, and then execute S201.

[0135] S221. Obtain the operating current I and no-load current I of the water pump 3 空载 , and then execute S222.

[0136] S222. Determine whether I > 1A holds. If it holds, execute S203; otherwise, execute S221.

[0137] Those skilled in the art can understand that although some of the embodiments described herein include certain features included in other embodiments rather than other features, the combination of the features of different embodiments means that it is within the scope of this application and forms different embodiments. For example, in the claims of this application, any one of the claimed embodiments can be used in any combination.

[0138] So far, the technical solutions of this application have 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 this application is obviously not limited to these specific embodiments. Without departing from the principle of this application, 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 all fall within the protection scope of this application.

Claims

1. A control method for a heat pump unit, characterized in that, The heat pump unit includes a water circulation loop, and a water flow switch is arranged on the water circulation loop. The control method includes: When the water flow switch is in the on state, determine whether the heat pump unit meets the anti-freezing mode condition; When the anti-freezing mode condition is met, control the heat pump unit to execute the anti-freezing mode; Wherein, the anti-freezing mode condition includes at least one of the following conditions: The inlet water temperature of the water circulation loop is less than the preset inlet water temperature; The temperature change rate of the inlet water temperature of the water circulation loop before and after the first set time is greater than the preset change rate.

2. The control method according to claim 1, wherein The step of "controlling the heat pump unit to execute the anti-freezing mode" further includes: Obtain the outlet water temperature of the water circulation loop; Calculate the difference between the outlet water temperature and the inlet water temperature; Compare the size of the difference with the preset difference; Based on the comparison result, determine the anti-freezing mode of the heat pump unit; Control the heat pump unit to execute the corresponding anti-freezing mode.

3. The control method according to claim 2, characterized in that, When a water pump is arranged on the water circulation loop, the anti-freezing mode includes a first mode and a second mode. The first mode is that the water pump operates at a first operating frequency, and the second mode is that the water pump operates at a second operating frequency; Wherein, the first operating frequency is less than the operating frequency of the water pump when the heat pump unit is in the normal mode, and the second operating frequency is greater than the operating frequency of the water pump when the heat pump unit is in the normal mode.

4. The control method according to claim 3, characterized in that, The step of "based on the comparison result, determine the anti-freezing mode of the heat pump unit" further includes: When the difference is greater than the preset difference, control the heat pump unit to operate according to the first mode; When the difference is less than or equal to the preset difference and greater than 0°C, control the heat pump unit to operate according to the second mode.

5. The control method according to claim 4, characterized in that The control method further includes: When the difference is less than or equal to 0°C, then control the water pump to stop operating.

6. The control method according to claim 5, characterized in that Simultaneously or after "controlling the water pump to stop operating" further includes: Send a reminder to remind to repair the water pump.

7. The control method according to claim 1, wherein The control method further includes: When the water flow switch is in the off state, obtain the operating current and no-load current of the water pump; Compare the size of the operating current and the no-load current; Based on the comparison result, judge whether there is water flow in the water circulation loop; When there is water flow in the water pump, judge whether the heat pump unit meets the anti-freezing mode condition.

8. The control method according to claim 7, characterized in that The step of "based on the comparison result, judge whether there is water flow in the water pump" further includes: When the operating current is greater than the no-load current, determine that there is water flow in the water circulation loop.

9. The control method according to claim 1, wherein Before the step of "judging whether the heat pump unit meets the anti-freezing mode condition" further includes: Obtain the ambient temperature; Compare the size of the ambient temperature with the preset ambient temperature; When the ambient temperature is less than the preset ambient temperature, judge whether the heat pump unit meets the anti-freezing mode condition.

10. The control method according to claim 1, wherein After the step of "controlling the heat pump unit to execute the anti-freezing mode" further includes: Every second set time, judge whether the heat pump unit meets the condition for exiting the anti-freezing mode; When the heat pump unit meets the condition for exiting the anti-freezing mode, control the heat pump unit to exit the anti-freezing mode; Wherein, the condition for exiting the anti-freezing mode includes the following two conditions: The inlet water temperature is greater than or equal to the preset inlet water temperature; The temperature change rate of the inlet water temperature around the third set time is less than or equal to the preset change rate.

Images