Defrosting control method and device and air conditioning unit

Abstract

The invention discloses a defrosting control method and device and an air conditioning unit. The method comprises the steps that the resistivity of the evaporator is obtained; frosting parameters of the evaporator are calculated according to the resistivity; the defrosting time is determined according to the frosting parameters, and a defrosting mode is further determined after defrosting is determined; wherein different defrosting modes correspond to different defrosting speeds. By means of the defrosting control method and device, the problems that under the condition of slight frosting, energy waste is caused by the adoption of a rapid defrosting mode, or under the condition of serious frosting, the defrosting effect is poor and normal operation of the system is affected due to the adoption of a slow defrosting mode can be solved, the defrosting mode is matched with the frosting degree, and the defrosting effect is guaranteed while energy is saved.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioners, and more particularly, to a defrosting control method, device and air conditioner unit. Background Art

[0002] With the popularization of refrigeration technology, the operating efficiency and reliability of air conditioner units in low-temperature environments have become the focus of user attention. Most of the current air conditioner units on the market use temperature thermosensors to monitor the evaporator at multiple points, or set a fixed defrost entry time point based on the defrosting operation time data obtained from multiple experiments before frosting. This method has the following problems: Single defrost mode: Using a single defrost mode (such as hot gas defrost or electric heating defrost), the most optimized defrost method cannot be selected according to the frosting degree, resulting in energy waste or poor defrosting effect. Inaccurate defrost timing: Defrosting in a fixed mode may cause premature defrosting when the evaporator is not frosted, wasting energy; or defrosting may not be started when the evaporator is already severely frosted, affecting efficiency.

[0003] In view of the problem in the prior art that the air conditioner unit cannot switch the defrost mode according to the actual frosting degree, resulting in energy waste or poor defrosting effect, no effective solution has been proposed yet. Summary of the Invention

[0004] Embodiments of the present invention provide a defrosting control method, device and air conditioner unit to solve the problem in the prior art that the air conditioner unit cannot switch the defrost mode according to the actual frosting degree, resulting in energy waste or poor defrosting effect.

[0005] To solve the above technical problems, the present invention provides a defrosting control method, which includes:

[0006] Obtain the resistivity of the evaporator;

[0007] Calculate the frosting parameter of the evaporator according to the resistivity;

[0008] Determine the defrost timing according to the frosting parameter and further determine the defrost mode after determining defrosting; wherein, different defrost modes have different defrost speeds.

[0009] Further, obtaining the resistivity of the evaporator includes:

[0010] Obtain the voltage between the inlet end and the outlet end of the copper tube in the evaporator and the current flowing through the copper tube;

[0011] Calculate the resistivity of the evaporator according to the voltage, the current, the cross-sectional area of the evaporator and the length of the evaporator.

[0012] Further, calculating the frosting parameter of the evaporator according to the resistivity is achieved according to the following formula:

[0013] U = K{T / Ti*ρ k +Td / T(ρ k -ρ k-1 )};

[0014] Wherein, U is the frosting parameter, K is the proportionality coefficient; Ti is the integral time constant; Td is the differential time constant; ρ k is the resistivity of the current sampling node, ρ k-1 is the resistivity of the previous sampling node, k is the sampling node number, and T is the time interval between the current sampling node and the previous sampling node.

[0015] Furthermore, the defrosting timing is determined according to the frosting parameter, and the defrosting mode is further determined after defrosting is determined, including:

[0016] After the frosting parameter reaches a preset threshold, it is determined to start defrosting and the defrosting mode is determined to be the first defrosting mode;

[0017] After a preset duration, it is judged whether the frosting parameter decreases;

[0018] If so, it is determined to continue defrosting and the defrosting mode remains the first defrosting mode;

[0019] If not, it is determined to continue defrosting and the defrosting mode is switched to the second defrosting mode;

[0020] Wherein, the defrosting speed corresponding to the first defrosting mode < the defrosting speed corresponding to the second defrosting mode.

[0021] Furthermore, after starting defrosting, the method further includes:

[0022] Judge whether the frosting parameter is less than the preset threshold;

[0023] If so, it is determined to stop defrosting.

[0024] The present invention also provides a defrosting control device, and the device includes:

[0025] A detection module for obtaining the resistivity of the evaporator;

[0026] A calculation module for calculating the frosting parameter of the evaporator according to the resistivity;

[0027] An intelligent control module for determining the defrosting timing according to the frosting parameter and further determining the defrosting mode after defrosting is determined; wherein, the defrosting speeds corresponding to different defrosting modes are different.

[0028] Furthermore, the detection module includes:

[0029] A detection chip, whose first pin is connected to the inlet end of the copper tube of the evaporator, whose second pin is connected to the outlet end of the copper tube, and the outlet end of the copper tube of the evaporator is grounded;

[0030] A detection resistor, whose first end is connected to the power supply and whose second end is connected to the inlet end of the copper tube.

[0031] The present invention also provides an air conditioner unit, including the above-mentioned defrost control device.

[0032] The present invention also provides a computer-readable storage medium, on which a computer program is stored, and when the program is executed by a processor, the above-mentioned defrost control method is implemented.

[0033] The present invention also provides an electronic device, including:

[0034] One or more processors;

[0035] A storage device for storing one or more programs, and when the one or more programs are executed by the one or more processors, the one or more processors implement the above-mentioned defrost control method.

[0036] Applying the technical solution of the present invention, the frosting parameter of the evaporator is calculated according to the resistivity of the evaporator. Since frosting will cause a change in the resistivity of the evaporator, the frosting parameter calculated based on the change in resistivity can characterize the thickness of the frost. Then, the defrosting timing is determined according to the frosting parameter, and further, the defrosting mode is determined after determining defrosting. In the case of severe frosting, a defrosting mode with a faster defrosting speed is adopted; in the case of slight frosting, a defrosting mode with a slower defrosting speed is adopted, avoiding the problem of energy waste caused by adopting a fast defrosting mode in the case of slight frosting, or poor defrosting effect caused by adopting a slow defrosting mode in the case of severe frosting, which affects the normal operation of the system, making the defrosting mode match the frosting degree, ensuring the defrosting effect while saving energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a flowchart of the defrost control method according to an embodiment of the present invention;

[0038] Figure 2 It is a flowchart of the defrost control method according to another embodiment of the present invention;

[0039] Figure 3 It is a change diagram of the frosting parameter according to an embodiment of the present invention;

[0040] Figure 4 It is a structural block diagram of the defrost control device according to an embodiment of the present invention;

[0041] Figure 5 It is a structural diagram of the detection module according to an embodiment of the present invention;

[0042] Figure 6 It is a schematic diagram of the hardware structure of an electronic device according to an embodiment of the present invention. Detailed implementation manners

[0043] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part rather than all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0044] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The singular forms "a", "said" and "the" used in the embodiments of the present invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. "Plural" generally includes at least two.

[0045] It should be understood that the term "and / or" used herein is only a relationship describing associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " herein generally represents an "or" relationship between the associated objects before and after.

[0046] It should be understood that although the terms first, second, etc. may be used in the embodiments of the present invention to describe defrosting modes, these defrosting modes should not be limited to these terms. These terms are only used to distinguish different defrosting modes. For example, without departing from the scope of the embodiments of the present invention, the first defrosting mode may also be called the second defrosting mode, and similarly, the second defrosting mode may also be called the first defrosting mode.

[0047] Depending on the context, the words "if", "when" as used herein may be interpreted as "when...", "when...", "in response to determining" or "in response to detecting". Similarly, depending on the context, the phrase "if determined" or "if detecting (stated condition or event)" may be interpreted as "when determined", "in response to determining", "when detecting (stated condition or event)", or "in response to detecting (stated condition or event)".

[0048] It should also be noted that the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a commodity or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such commodity or device. Without further limitation, an element defined by the statement "comprising one..." does not exclude the presence of additional identical elements in the commodity or device comprising said element.

[0049] The optional embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0050] Embodiment 1

[0051] Most of the air conditioner units on the current market use a temperature thermosensitive bulb to monitor the evaporator at multiple points, or set a fixed defrost entry time point based on the defrost pre-cooling operation time data obtained through multiple experiments. This method has the following problems: single defrost mode: a single defrost mode (such as hot gas defrost or electric heating defrost) is adopted, and the most optimized defrost method is not selected according to the degree of frosting, resulting in energy waste or poor defrost effect. Inaccurate defrost timing: Fixed-mode defrost may cause premature defrost when the evaporator is not frosted, wasting energy; or defrost may not be started when the evaporator is already severely frosted, affecting efficiency.

[0052] In view of the problem that the air conditioner unit in the prior art cannot switch the defrost mode according to the actual frosting degree, resulting in energy waste or poor defrost effect, this embodiment provides a defrost control method. Figure 1 As shown in the flowchart of the defrost control method according to the embodiment of the present invention, Figure 1 the above method includes:

[0053] S101, obtain the resistivity of the evaporator.

[0054] There is a copper tube inside the evaporator. The resistivity of copper decreases as the temperature decreases. According to Matthiessen's rule, the conductivity of copper at low temperatures is mainly affected by lattice vibration. The lower the temperature, the weaker the lattice vibration and the higher the conductivity. However, after the copper tube is frosted, the ice layer will cover the surface, increasing the contact resistance, especially at the connection points. The conductivity will change from an upward trend to a downward trend after frosting. Since the resistivity and conductivity are inversely proportional, the resistivity of the evaporator will increase after frosting, and the amount of frosting is not easy to detect, while the change in resistivity is easier to detect. Therefore, the frosting situation can be characterized by the change in the resistivity of the evaporator. An algorithm can be judged based on this resistivity change trend, and the degree of frosting can be judged more accurately.

[0055] S102, calculate the frosting parameter of the evaporator according to the resistivity of the evaporator.

[0056] In order to accurately relate the change in resistivity to the frost thickness, a new quantity, the frost parameter, needs to be introduced. This frost parameter is calculated from the resistivity and is used to characterize the frost thickness. If the frost parameter increases linearly, it indicates that the frost layer is thickening at a uniform speed; if the frost parameter remains unchanged, it indicates that the frost layer has not changed; if the growth of the frost parameter slows down, it indicates that the frosting speed has decreased, that is, the defrost operation has reduced the frosting speed; if the frost parameter decreases, it indicates that the frost layer is thinning, that is, the defrost operation has played a positive role and achieved effective defrosting.

[0057] For detecting the frost layer thickness, in the prior art, there is a scheme of judging the frost layer thickness by the micro electrical signals output by two electrodes respectively installed at positions with different heights from the surface of the evaporator. However, this method can only detect the frost layer thickness at the positions where the electrodes are set, and the detection result cannot reflect the frosting situation of the entire evaporator surface. In this application, the change in resistivity is used to characterize the frost layer thickness. Frost formation at any part of the evaporator surface will cause a change in the overall resistivity of the evaporator, and the change in resistivity can reflect the overall frost thickness of the evaporator. In addition, in the prior art, there is also a scheme of setting two parallel electrodes, collecting the frost formed by the refrigeration equipment through the space between the two electrodes, and judging the frost thickness by detecting the resistance value between the two electrodes. However, the size of the electrodes needs to be the same as or larger than the evaporator, which increases the volume and occupied space of the evaporator. At the same time, since the two electrodes cover part of the surface of the evaporator, the cooling effect will be poor. In this application, by detecting the overall resistivity of the evaporator, the detection can be carried out by connecting lines at both ends of the evaporator, and the detection device will not cover the surface of the evaporator and will not increase the volume of the evaporator.

[0058] S103, determine the defrost timing according to the frost parameter and further determine the defrost mode after determining defrost; wherein, the defrost speed corresponding to different defrost modes is different.

[0059] Based on the value and change trend of the above-mentioned frost parameter, the change in the thickness of the frost layer is deduced, and then the corresponding defrost mode is adopted, that is, in the case of severe frosting, a defrost mode with a faster defrost speed is adopted; in the case of slight frosting, a defrost mode with a slower defrost speed is adopted.

[0060] The defrost control method of this embodiment calculates the frosting parameter of the evaporator according to the resistivity of the evaporator. Since frosting will cause a change in the resistivity of the evaporator, the frosting parameter calculated based on the change in resistivity can characterize the thickness of the frost. Then, the defrost timing is determined according to the frosting parameter, and the defrost mode is further determined after the defrost is determined. In the case of severe frosting, a defrost mode with a faster defrosting speed is adopted; in the case of slight frosting, a defrost mode with a slower defrosting speed is adopted, avoiding the problem of energy waste caused by adopting a fast defrost mode in the case of slight frosting, or poor defrosting effect caused by adopting a slow defrost mode in the case of severe frosting, which affects the normal operation of the system, making the defrost mode match the frosting degree, and ensuring the defrosting effect while saving energy.

[0061] The resistance value R of the evaporator can be calculated by the voltage and current at both ends of the evaporator, and the resistivity ρ = R*(A / L), where A is the cross-sectional area of the evaporator and L is the length of the evaporator. Therefore, obtaining the resistivity of the evaporator includes: obtaining the voltage V_drop between the inlet end and the outlet end of the copper tube in the evaporator and the current I flowing through the copper tube; calculating the resistivity ρ of the evaporator according to the voltage V_drop, the current I, the cross-sectional area A of the evaporator and the length L of the evaporator. That is, the resistance value R of the evaporator is calculated by V_drop / I, and then the resistivity ρ is calculated by R*(A / L). The unit of the resistivity ρ: ohm·meter (Ω·m); the unit of the resistance value R of the evaporator: ohm (Ω); the unit of the cross-sectional area A of the evaporator: square meter (m2); the unit of the length L of the evaporator: meter (m).

[0062] The thickness of the frost layer is an accumulated quantity, and the frosting speed is a process quantity. Since the frosting process still continues during the general defrost process, therefore, through the frosting speed, it is more able to truly predict the thickness of the frost at the next moment. When calculating the frosting parameter, both the resistivity of the current node and the change in the resistivity of the current node are considered, rather than only considering the resistivity of the current node, which can more accurately predict the thickness of the frost layer at the next node, and then more accurately select the defrost mode. And the change in the resistivity of the current node is related to the resistivity of the current node and the resistivity of the previous node. Therefore, calculating the frosting parameter of the evaporator according to the resistivity is realized according to the following formula: U = K{T / Ti*ρ k +Td / T(ρ k -ρ k-1 )}; where U is the frosting parameter, K is the proportionality coefficient; Ti is the integral time constant; Td is the differential time constant; ρ k is the resistivity of the current sampling node, ρ k-1 is the resistivity of the previous sampling node, k is the sampling node number, and T is the time interval between the current sampling node and the previous sampling node.

[0063] The function of the above formula is to obtain several coefficient parameters based on the variation of resistivity and frosting conditions through multiple experiments, accurately process the change in the resistivity of the evaporator copper tube within the duration T obtained by sampling, calculate the frosting parameter, and compare it with the defrosting threshold obtained through experiments to perform defrosting control.

[0064] Parameter analysis:

[0065] The proportional coefficient K is the proportional value of the frosting thickness of the sensor obtained through experiments and the actual frosting thickness on the evaporator. This proportional coefficient K is used for the conversion of thickness values.

[0066] k and k - 1 represent the current sampling node and the previous sampling node.

[0067] T is the time interval between the current sampling node and the previous sampling node, that is, the sampling period, such as sampling once every 1 s, sampling once every 500 ms, etc.

[0068] Ti is the integral time constant, and this constant value is obtained through experiments. Its function is to eliminate the steady-state error of the system and enable the algorithm to reach the value. The integral time constant Ti determines the influence degree of the integral term on the algorithm output. Larger Ti: indicates weaker integral action, slower system response speed, but better stability, suitable for situations with larger sampling periods; Smaller Ti: indicates stronger integral action, faster system response speed, but prone to overshoot and oscillation, suitable for situations with smaller sampling periods. In practical applications, it is necessary to adjust the value of Ti according to specific application scenarios and system characteristics to achieve the best control effect.

[0069] Td is the differential time constant, and this constant value is also obtained through experiments. Its function is to predict the future behavior of the algorithm, reduce the dynamic error by adjusting the control quantity in advance, and improve the response speed and stability of the system. Larger Td: indicates stronger differential action, the system reacts more sensitively to changes, can adjust the control quantity faster, but is prone to amplifying the difference between the previous and current periods, resulting in system instability, so it is suitable for systems with smaller fluctuations in frosting degree; Smaller Td: indicates weaker differential action, the system reacts slower to changes, but has better stability, suitable for systems with larger fluctuations in frosting degree. In practical applications, it is necessary to adjust the value of Td according to specific application scenarios and system characteristics to achieve the best control effect.

[0070] In this embodiment, in order to accurately reflect the frosting thickness of the next node through the resistivity and the change of resistivity, parameters such as K, T, Ti, and Td are introduced to calculate the frosting parameters. Of course, in other embodiments of the present invention, the defrosting mode can also be directly switched with reference to the frosting speed, that is, the change amount of resistivity is used as the frosting parameter, that is, U = Δρk = ρk - ρk-1, where ρk is the resistivity of the current sampling node, ρk-1 is the resistivity of the previous sampling node, and k is the sampling node number.

[0071] Considering that the frosting thickness will change after the defrosting mode is executed, in order to ensure that the defrosting speed always matches the frosting situation during the defrosting process and to ensure the energy efficiency and defrosting effect of the unit, this embodiment provides a preferred implementation manner to switch the defrosting mode according to the real-time frosting thickness of the evaporator. Specifically: determine the defrosting timing according to the frosting parameter and further determine the defrosting mode after determining the defrosting, including: after the frosting parameter reaches the preset threshold U1, determine to start defrosting and determine the defrosting mode as the first defrosting mode; after a preset time t1, judge whether the frosting parameter decreases; if so, determine to continue defrosting and determine that the defrosting mode remains the first defrosting mode; if not, determine to continue defrosting and determine that the defrosting mode switches to the second defrosting mode; where the defrosting speed corresponding to the first defrosting mode < the defrosting speed corresponding to the second defrosting mode. In this embodiment, the first defrosting mode can be the hot gas defrosting mode, that is, defrosting is performed through high-temperature refrigerant, and the second defrosting mode can be the electric heating defrosting, that is, defrosting is performed through a heating device arranged near the evaporator, and the heating device can use a PTC heating sheet.

[0072] In order to avoid starting defrosting when frosting just begins and does not affect the operation of the air-conditioning unit, resulting in waste of energy, therefore, defrosting is determined only after the frosting parameter reaches the preset threshold U1. In the initial stage of defrosting, the frosting parameter is low and the frost layer is thin. First, the first defrosting mode with a relatively slow defrosting speed is adopted. After a period of time (preset time t1), if the frosting parameter starts to decrease, it indicates that the frost layer becomes thinner and the amount of melted frost is greater than the amount of newly formed frost. The first defrosting mode can effectively defrost. In order to save energy, the first defrosting mode can continue to be used for defrosting; if the frosting parameter is still increasing, but the growth rate slows down, it indicates that although the first defrosting mode can slow down the frosting speed, it cannot effectively defrost. Therefore, the second defrosting mode with a faster defrosting speed is enabled.

[0073] In order to avoid continuing defrosting when the frost layer melts to a state where it does not affect the operation of the air-conditioning unit, resulting in waste of energy, after starting defrosting, the above method further includes: judging whether the frosting parameter is less than the preset threshold U1; if so, determine to stop defrosting; if not, continue defrosting while maintaining the current defrosting mode.

[0074] Embodiment 2

[0075] Another defrosting control method is provided in this embodiment. Figure 2 As shown in the flowchart of the defrosting control method according to another embodiment of the present invention, Figure 2 as shown, the method includes:

[0076] S1. Obtain the resistivity of the evaporator in real time.

[0077] The resistivity ρ of the evaporator = R * (A / L), where R = V_drop / I; V_drop is the voltage across the evaporator, I is the current flowing through the copper pipe, and the unit of resistivity ρ is ohm-meter (Ω·m); the unit of the resistance value R of the evaporator is ohm (Ω); the unit of the cross-sectional area A of the evaporator is square meter (m 2 ²); the unit of the length L of the evaporator is meter (m).

[0078] S2. Calculate the frosting parameter U according to the resistivity of the evaporator.

[0079] Where U = K{T / Ti * ρ k + Td / T(ρ k - ρ k-1 )}; where U is the frosting parameter, K is the proportionality coefficient; Ti is the integral time constant; Td is the differential time constant; ρ k is the resistivity of the current sampling node, ρ k-1 is the resistivity of the previous sampling node, k is the sampling node number, and T is the time interval between the current sampling node and the previous sampling node.

[0080] S3. Determine whether the frosting parameter is greater than or equal to the preset threshold U1; if not, execute step S4, if so, execute step S5.

[0081] S4. Control the air conditioner unit to operate normally without defrosting.

[0082] S5. Control the air conditioner unit to defrost and select the hot gas defrosting mode.

[0083] S6. After a preset duration, determine whether the frosting parameter decreases; if so, return to step S5, if not, execute step S7.

[0084] S7. Control the air conditioner unit to switch to the electric heating defrosting mode.

[0085] To avoid defrosting when the air conditioner unit starts to frost but the operation is not affected, resulting in waste of energy, defrosting is determined only after the frost formation parameter reaches the preset threshold U1. In the initial stage of defrosting, the frost formation parameter is relatively low and the frost layer is thin. First, the hot gas defrosting mode with a relatively slow defrosting speed is adopted. After a period of time (preset duration t1), if the frost formation parameter starts to decrease, indicating that the frost layer becomes thinner and the amount of defrosted frost is greater than the newly formed frost, the first defrosting mode can effectively defrost. To save energy, the hot gas defrosting mode can continue to be used for defrosting; if the frost formation parameter is still increasing but the growth rate slows down, it indicates that although the first defrosting mode can slow down the frost formation speed, it cannot effectively defrost. Therefore, the electric heating defrosting mode with a faster defrosting speed is enabled.

[0086] S8, determine whether the frost formation parameter is less than the preset threshold U1; if so, execute step S9, if not, execute step S10.

[0087] S9, stop defrosting.

[0088] S10, continue defrosting in the current defrosting mode.

[0089] Figure 3 As shown in the graph of the change of the frost formation parameter according to the embodiment of the present invention, Figure 3 When the frost formation parameter U reaches the preset threshold U1, the hot gas defrosting mode is adopted for defrosting. After adopting the hot gas defrosting, the growth rate of the frost formation parameter slows down, indicating that the frost formation speed is still greater than the defrosting speed and the thickness of the frost layer is still increasing, but only the growth rate becomes slower and effective defrosting is not achieved. After this situation lasts for the preset duration, the electric heating defrosting mode is turned on. At this time, the defrosting speed starts to be greater than the frost formation speed and the frost formation parameter decreases, indicating that the thickness of the frost layer decreases until the frost formation parameter is less than the preset threshold U1 and defrosting stops.

[0090] To avoid continuing defrosting when the frost layer melts to a state where it does not affect the operation of the air conditioner unit, resulting in waste of energy, after starting defrosting, it is necessary to determine whether the frost formation parameter decreases to the above preset threshold U1; if so, it is determined to stop defrosting.

[0091] The defrosting control method of this embodiment can also have a self-learning ability, which can optimize the frost formation parameter threshold and the defrosting mode selection logic according to environmental conditions and operation data, improving the adaptability and intelligent level of the system.

[0092] In this embodiment, comprehensive analysis and processing can be carried out based on the resistivity and the change data of the resistivity to dynamically adjust the defrosting mode to ensure the efficiency and reliability of the defrosting process. The system can also be set with a fault detection and diagnosis function to timely detect sensor failures or defrosting system abnormalities and take corresponding measures to ensure the stable operation of the system.

[0093] Through the above method, the present invention can achieve the following effects: First, intelligent defrost control is realized: the frosting degree of the evaporator is monitored in real time, and the defrosting timing is accurately judged, avoiding the defects of traditional fixed-mode defrosting. Second, staged defrosting is realized: the optimal defrosting mode is selected according to the frosting degree, improving the defrosting efficiency and energy utilization rate. Third, the equipment life is extended: by intelligently controlling the defrosting process, equipment damage caused by excessive defrosting or untimely defrosting is reduced, and the service life of the air-conditioning system is extended.

[0094] Embodiment 3

[0095] This embodiment provides a defrost control device. Figure 4 As shown in the structural block diagram of the defrost control device according to the embodiment of the present invention, Figure 4 shown, the defrost control device includes:

[0096] A detection module 10 for obtaining the resistivity of the evaporator.

[0097] There is a copper tube inside the evaporator. The resistivity of copper decreases as the temperature drops. According to Matthiessen's rule, the conductivity of copper at low temperatures is mainly affected by lattice vibration. The lower the temperature, the weaker the lattice vibration and the higher the conductivity. However, after the copper tube is frosted, the ice layer will cover the surface, increasing the contact resistance, especially at the connection points. The conductivity will change from an upward trend to a downward trend after frosting. Since the resistivity and conductivity are inversely proportional, therefore, after the evaporator is frosted, the resistivity will increase, and the amount of frost is not easy to detect, while the change in resistivity is easy to detect. Therefore, the frosting situation can be characterized by the change in the resistivity of the evaporator. The frosting degree can be judged through algorithmic judgment based on this resistivity change trend.

[0098] A calculation module 20 for calculating the frosting parameter of the evaporator according to the resistivity.

[0099] In order to accurately relate the resistivity change to the frost thickness, a new quantity, the frosting parameter, needs to be introduced. This frosting parameter is calculated from the resistivity and is used to characterize the frost thickness. If the frosting parameter grows linearly, it indicates that the frost layer is thickening at a uniform speed; if the frosting parameter remains unchanged, it indicates that the frost layer has not changed; if the growth of the frosting parameter slows down, it indicates that the frosting speed has slowed down, that is, the defrosting operation has reduced the frosting speed; if the frosting parameter decreases, it indicates that the frost layer is thinning, that is, the defrosting operation has played a positive role and effective defrosting has been achieved.

[0100] An intelligent control module 30 for determining the defrosting timing according to the frosting parameter and further determining the defrosting mode after determining defrosting; wherein, different defrosting modes correspond to different defrosting speeds.

[0101] Based on the numerical values and variation trends of the above-mentioned frosting parameters, the thickness variation of the frost layer is deduced, and then the corresponding defrosting mode is adopted. That is, in the case of severe frosting, a defrosting mode with a faster defrosting speed is adopted; in the case of slight frosting, a defrosting mode with a slower defrosting speed is adopted.

[0102] The defrosting control device of this embodiment calculates the frosting parameters of the evaporator by the calculation module 20 according to the resistivity of the evaporator. Since frosting will cause changes in the resistivity of the evaporator, the frosting parameters calculated based on the change of resistivity can characterize the thickness of the frost. Then, the intelligent control module 30 determines the defrosting timing according to the frosting parameters and further determines the defrosting mode after determining defrosting. In the case of severe frosting, a defrosting mode with a faster defrosting speed is adopted; in the case of slight frosting, a defrosting mode with a slower defrosting speed is adopted, avoiding the problem of energy waste caused by adopting a fast defrosting mode in the case of slight frosting, or poor defrosting effect caused by adopting a slow defrosting mode in the case of severe frosting, which affects the normal operation of the system, making the defrosting mode match the frosting degree, ensuring the defrosting effect while saving energy.

[0103] Figure 5 As shown in the structural diagram of the detection module according to an embodiment of the present invention, Figure 5 As shown, the detection module 10 includes: a detection chip 101, whose first pin is connected to the inlet end of the copper tube of the evaporator, whose second pin is connected to the outlet end of the copper tube, and the outlet end of the copper tube of the evaporator is grounded; a detection resistor Rx, whose first end is connected to the power supply and whose second end is connected to the inlet end of the copper tube.

[0104] In an embodiment of the present invention, the detection chip 101 is selected as an intelligent control chip with an ADC pin.

[0105] For detecting the thickness of the frost layer, in the prior art, there is a solution to judge the frost layer thickness based on the micro electrical signals output by two electrodes respectively installed at different heights from the surface of the evaporator. However, this method can only detect the frost layer thickness at the positions where the electrodes are set, and the detection result cannot reflect the frosting condition of the entire evaporator surface. In this application, the change in resistivity is used to characterize the frost layer thickness. Frosting at any part of the evaporator surface will cause a change in the overall resistivity of the evaporator, and the change in resistivity can reflect the overall frosting thickness of the evaporator. In addition, in the prior art, there are also two parallel electrodes. The condensed frost generated by the refrigeration equipment is accommodated in the space between the two electrodes, and the frosting thickness is judged by detecting the resistance value between the two electrodes. However, the size of the electrodes needs to be the same as or larger than the evaporator, which increases the volume and occupied space of the evaporator. At the same time, since the two electrodes cover part of the evaporator surface, the cooling effect will be poor. In this application, to detect the overall resistivity of the evaporator, the circuit can be connected to both ends of the evaporator for detection. The detection device will not cover the evaporator surface and will not increase the volume of the evaporator.

[0106] The resistance value R of the evaporator can be calculated from the voltage and current at both ends of the evaporator, and the resistivity ρ = R * (A / L), where A is the cross-sectional area of the evaporator and L is the length of the evaporator. Therefore, to obtain the resistivity of the evaporator, it includes: obtaining the voltage V_drop between the inlet end and the outlet end of the copper tube in the evaporator and the current I flowing through the copper tube; calculating the resistivity ρ of the evaporator according to the voltage V_drop, the current I, the cross-sectional area A of the evaporator, and the length L of the evaporator. That is, the resistance value R of the evaporator is calculated by V_drop / I, and then the resistivity ρ is calculated by R * (A / L). The unit of the resistivity ρ: ohm-meter (Ω·m); the unit of the resistance value R of the evaporator: ohm (Ω); the unit of the cross-sectional area A of the evaporator: square meter (m 2 ); the unit of the length L of the evaporator: meter (m).

[0107] The thickness of the frost layer is an accumulated quantity, while the frosting speed is a process quantity. Since the frosting process still continues during the general defrosting process, therefore, through the frosting speed, it is more capable of truly predicting the frost layer thickness at the next moment. When calculating the frosting parameters, considering both the resistivity at the current node and the change in the resistivity at the current node, rather than only considering the resistivity at the current node, can more accurately predict the frost layer thickness at the next node, and thus more accurately select the defrosting mode. And the change in the resistivity at the current node is related to the resistivity at the current node and the resistivity at the previous node. Therefore, to calculate the frosting parameters of the evaporator based on the resistivity, it is realized according to the following formula: U = K{T / Ti * ρ k +Td / T(ρ k -ρ k-1)}; where U is the frosting parameter, K is the proportionality coefficient; Ti is the integral time constant; Td is the derivative time constant; ρ k is the resistivity of the current sampling node, and ρ k-1 is the resistivity of the previous sampling node, k is the sampling node number, and T is the time interval between the current sampling node and the previous sampling node.

[0108] The function of the above formula is to obtain several coefficient parameters based on the variation of resistivity and frosting conditions obtained through multiple experiments, accurately process the change in resistivity of the evaporator copper tube within the duration T obtained by sampling, calculate the frosting parameter, and compare it with the defrosting threshold obtained through experiments to perform defrosting control.

[0109] Parameter analysis:

[0110] The proportionality coefficient K is the proportional value of the frosting thickness of the sensor obtained through experiments and the actual frosting thickness on the evaporator, and this proportionality coefficient K is used for the conversion of thickness values.

[0111] k and k - 1 represent the current sampling node and the previous sampling node.

[0112] T is the time interval between the current sampling node and the previous sampling node, that is, the sampling period, such as sampling once every 1 s, sampling once every 500 ms, etc.

[0113] Ti is the integral time constant, and this constant value is obtained through experiments. Its function is to eliminate the steady-state error of the system and enable the algorithm to reach the value. The integral time constant Ti determines the influence degree of the integral term on the algorithm output. When Ti is larger: it means the integral effect is weaker, the system response speed is slower, but the stability is better, which is suitable for the case of a larger sampling period; when Ti is smaller: it means the integral effect is stronger, the system response speed is faster, but it is easy to cause overshoot and oscillation, which is suitable for the case of a smaller sampling period. In practical applications, the value of Ti needs to be adjusted according to the specific application scenario and system characteristics to achieve the best control effect.

[0114] Td is the derivative time constant, and this constant value is also obtained through experiments. Its function is to predict the future behavior of the algorithm, reduce the dynamic error by adjusting the control quantity in advance, and improve the system response speed and stability. When Td is larger: it means the derivative effect is stronger, the system responds more sensitively to changes, and can adjust the control quantity faster, but it is easy to amplify the difference between the previous and current periods, resulting in system instability, so it is suitable for systems with less fluctuation in frosting degree; when Td is smaller: it means the derivative effect is weaker, the system responds slower to changes, but the stability is better, which is suitable for systems with larger fluctuation in frosting degree. In practical applications, the value of Td needs to be adjusted according to the specific application scenario and system characteristics to achieve the best control effect.

[0115] In this embodiment, in order to accurately reflect the frosting thickness of the next node through the resistivity and the change in resistivity, parameters such as K, T, Ti, and Td are introduced to calculate the frosting parameters. Of course, in other embodiments of the present invention, the defrosting mode can also be directly switched with reference to the frosting speed, that is, the change amount of the resistivity is used as the frosting parameter, that is, U = Δρ k = ρ k −ρ k-1 , where ρk is the resistivity of the current sampling node, ρk - 1 is the resistivity of the previous sampling node, and k is the sampling node number.

[0116] In order to further realize switching the defrosting mode according to the real-time frosting thickness, the intelligent control module 30 is specifically configured to: after the frosting parameter reaches the preset threshold U1, determine to start defrosting and determine that the defrosting mode is the first defrosting mode; after a preset duration t1, determine whether the frosting parameter decreases; if so, determine to continue defrosting and determine that the defrosting mode remains the first defrosting mode; if not, determine to continue defrosting and determine that the defrosting mode is switched to the second defrosting mode; where the defrosting speed corresponding to the first defrosting mode < the defrosting speed corresponding to the second defrosting mode. In this embodiment, the first defrosting mode can be the hot gas defrosting mode, that is, defrosting is performed through high-temperature refrigerant, and the second defrosting mode can be the electric heating defrosting, that is, defrosting is performed through a heating device arranged near the evaporator, and the heating device can use a PTC heating sheet.

[0117] In order to avoid starting defrosting at the beginning of frosting when it does not affect the operation of the air-conditioning unit, resulting in waste of energy, therefore, defrosting is determined only after the frosting parameter reaches the preset threshold U1. In the initial stage of defrosting, the frosting parameter is low and the frost layer is thin. First, the first defrosting mode with a relatively slow defrosting speed is adopted. After a period of time (preset duration t1), if the frosting parameter starts to decrease, it indicates that the frost layer becomes thinner and the amount of melted frost is greater than the amount of newly formed frost, indicating that the first defrosting mode can effectively defrost. In order to save energy, the first defrosting mode can be continued to defrost; if the frosting parameter is still increasing but the growth rate slows down, it indicates that although the first defrosting mode can slow down the frosting speed, it cannot effectively defrost. Therefore, the second defrosting mode with a faster defrosting speed is enabled.

[0118] In order to avoid continuing defrosting when the frost layer melts to a state where it does not affect the operation of the air-conditioning unit, resulting in waste of energy, the above-mentioned intelligent control module 30 is further configured to: after starting defrosting, determine whether the frosting parameter is less than the preset threshold U1; if so, determine to stop defrosting; if not, continue defrosting in the current defrosting mode.

[0119] Embodiment 4

[0120] This embodiment provides an air-conditioning unit, including the above-mentioned defrosting control device.

[0121] Example 5

[0122] This embodiment provides a computer-readable storage medium, on which a computer program is stored. When the program is executed by a processor, the above defrosting control method is implemented.

[0123] Example 6

[0124] This embodiment provides an electronic device, including:

[0125] One or more processors;

[0126] A storage device for storing one or more programs. When the one or more programs are executed by the one or more processors, the one or more processors implement the above defrosting control method.

[0127] Figure 6 Schematic diagram of the hardware structure of the electronic device according to an embodiment of the present invention, as Figure 6 shown, the electronic device includes:

[0128] One or more processors 610 and a memory 620, Figure 6 Taking one processor 610 as an example.

[0129] The above electronic device may further include: an input device 630, an output device 640.

[0130] The processor 610, the memory 620, the input device 630, and the output device 640 may be connected through a bus or other means, Figure 6 Taking connection through a bus as an example.

[0131] The memory 620, as a non-volatile computer-readable storage medium, can be used to store non-volatile software programs, non-volatile computer-executable programs, and modules, such as program instructions / modules corresponding to the defrosting control method in the embodiments of the present invention. The processor 610 executes various functional applications and data processing of the server by running the non-volatile software programs, instructions, and modules stored in the memory 620, that is, implements the above method embodiments.

[0132] The memory 620 may include a program storage area and a data storage area. Among them, the program storage area may store an operating device and application programs required for at least one function; the data storage area may store data created according to the use of the defrosting control device, etc. In addition, the memory 620 may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one magnetic disk storage device, a flash memory device, or other non-volatile solid-state storage devices.

[0133] The input device 630 can receive input digital or character information and generate key signal inputs related to user settings and function controls of the electronic device. The output device 640 can include display devices such as a display screen.

[0134] The one or more modules are stored in the memory 620 and, when executed by the one or more processors 610, perform the defrost control method in any of the above method embodiments.

[0135] The above electronic device product can execute the method provided by the embodiments of the present invention and has functional modules and beneficial effects corresponding to the execution of the method. For technical details not described in detail in this embodiment, reference can be made to the method provided by the embodiments of the present invention.

[0136] The electronic devices in the embodiments of the present invention exist in various forms, including but not limited to:

[0137] (1) Mobile communication devices: These devices are characterized by having mobile communication functions and mainly aim to provide voice and data communication. Such terminals include: smart phones (such as iPhone), multimedia phones, functional phones, and low-end phones, etc.

[0138] (2) Ultra-mobile personal computer devices: These devices belong to the category of personal computers, have computing and processing functions, and generally also have the characteristic of mobile Internet access. Such terminals include: PDA, MID, and UMPC devices, etc., such as iPad.

[0139] (3) Portable entertainment devices: These devices can display and play multimedia content. Such devices include: audio and video players (such as iPod), handheld game consoles, e-books, and smart toys and portable vehicle navigation devices.

[0140] (4) Servers: Devices that provide computing services. The composition of a server includes a processor, hard disk, memory, device bus, etc. Servers are similar to general computer architectures, but due to the need to provide highly reliable services, they have higher requirements in terms of processing power, stability, reliability, security, scalability, and manageability.

[0141] (5) Other electronic devices with data interaction functions, such as televisions, in-vehicle large screens, etc.

[0142] The device embodiments described above are merely illustrative. The modules described as separate components may or may not be physically separated, and the components shown as modules may or may not be physical modules, that is, they may be located in one place or distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0143] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on such an understanding, the essence of the above technical solution, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0144] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. And these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A defrost control method, characterized in that, The method includes: Obtaining the resistivity of the evaporator; Calculating the frosting parameter of the evaporator according to the resistivity; Determining the defrosting timing according to the frosting parameter and further determining the defrosting mode after determining defrosting; wherein, the defrosting speeds corresponding to different defrosting modes are different.

2. The method according to claim 1, characterized in that, Obtaining the resistivity of the evaporator includes: Obtaining the voltage between the inlet end and the outlet end of the copper tube in the evaporator and the current flowing through the copper tube; Calculating the resistivity of the evaporator according to the voltage, the current, the cross-sectional area of the evaporator and the length of the evaporator.

3. The method according to claim 1, characterized in that, Calculating the frosting parameter of the evaporator is achieved according to the following formula: U = K{T / Ti * ρ k + Td / T(ρ k - ρ k-1 )}; where U is the frosting parameter, K is the proportionality coefficient; Ti is the integral time constant; Td is the derivative time constant; ρ k is the resistivity of the current sampling node, ρ k-1 is the resistivity of the previous sampling node, k is the sampling node number, and T is the time interval between the current sampling node and the previous sampling node.

4. The method according to claim 1, characterized in that, Determining the defrosting timing according to the frosting parameter and further determining the defrosting mode after determining defrosting includes: After the frosting parameter reaches a preset threshold, determining to start defrosting and determining the defrosting mode as the first defrosting mode; After a preset time period, determining whether the frosting parameter decreases; If so, determining to continue defrosting and determining that the defrosting mode remains the first defrosting mode; If not, determining to continue defrosting and determining that the defrosting mode switches to the second defrosting mode; Wherein, the defrosting speed corresponding to the first defrosting mode < the defrosting speed corresponding to the second defrosting mode.

5. The method according to claim 4, characterized in that, After determining to start defrosting, the method further includes: Determining whether the frosting parameter is less than the preset threshold; If so, determining to stop defrosting.

6. A defrost control device, characterized in that, The device includes: A detection module, configured to obtain the resistivity of the evaporator; A calculation module, configured to calculate the frosting parameter of the evaporator according to the resistivity; An intelligent control module, configured to determine the defrosting timing according to the frosting parameter and further determine the defrosting mode after determining defrosting; wherein, the defrosting speeds corresponding to different defrosting modes are different.

7. The device according to claim 6, characterized in that, The detection module includes: A detection chip, whose first pin is connected to the inlet end of the copper tube of the evaporator, whose second pin is connected to the outlet end of the copper tube, and the outlet end of the copper tube of the evaporator is grounded; A detection resistor, whose first end is connected to the power supply and whose second end is connected to the inlet end of the copper tube.

8. An air-conditioning unit, characterized in that, Including the defrosting control device according to claim 6 or 7.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by a processor, it implements the method according to any one of claims 1 to 5.

10. An electronic device, characterized in that, Including: One or more processors; A storage device, configured to store one or more programs, and when the one or more programs are executed by the one or more processors, enabling the one or more processors to implement the method according to any one of claims 1 to 5.

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