Defrosting control method and device of multi-split air conditioner and multi-split air conditioner

Abstract

The invention relates to the technical field of air conditioners, and provides a defrosting control method and device of a multi-split air conditioner and the multi-split air conditioner. The control method of the multi-split air conditioner comprises the steps that when it is determined that defrosting conditions are met, the running state of each outdoor fan is obtained, whether the corresponding outdoor unit is frosted or not is determined according to the running state of each outdoor fan and a preset frosting judgment condition; and when all the outdoor units are frosted, the multiple outdoor units are controlled to conduct defrosting in sequence from the high position to the low position. When the multi-split air conditioner meets the defrosting condition, heat of defrosting water generated when the outdoor unit at the high position defrosts is used for melting a frost layer at the low position, energy consumption generated when the outdoor unit at the low position defrosts is reduced, the use cost of a user is reduced, the mobility of the surface of the outdoor heat exchanger can be improved through the defrosting water, and the service life of the outdoor heat exchanger is prolonged. Incomplete defrosting caused by the fact that ice blocks are clamped between the fins of the heat exchanger is avoided, and the defrosting effect is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioners, and in particular to a defrosting control method and a control device for a multi-split air conditioner, and the multi-split air conditioner. Background Art

[0002] Multi-split air conditioners have been widely used because the number of internal and external units and output capacity can be freely adjusted according to demand. In the low temperature environment in winter, due to the large demand for heat on the indoor side, the outdoor heat exchanger often enters a frosted state. The frost layer of the outdoor heat exchanger will reduce the heat exchange efficiency, increase energy consumption, and reduce the heating effect of the indoor unit. In the related art, due to the large size of the multi-split outdoor unit heat exchanger, multiple outdoor heat exchangers are often installed in parallel to save space. The refrigerant flow and refrigerant pressure of each outdoor unit are controlled by multiple electronic expansion valves, thereby realizing the flow control of the whole machine. When defrosting multiple outdoor units of a multi-split air conditioner, if multiple outdoor heat exchangers are defrosted at the same time, the energy consumption is relatively large, which increases the user's usage cost. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the related art. To this end, the present invention proposes a defrosting control method for a multi-split air conditioner, wherein at least two of the multiple outdoor units are arranged from high to low in height direction, and when the defrosting conditions are met, the multiple outdoor units are controlled to be defrosted in sequence from high to low, and the heat of the defrosting water of the outdoor unit at a higher position can be used to melt the frost layer at a lower position, thereby reducing the energy consumption of the outdoor unit at a lower position when defrosting, and reducing the user's use cost.

[0004] The invention also provides a control device for a multi-split air conditioner.

[0005] The invention also provides a multi-split air conditioner.

[0006] According to a defrost control method for a multi-split air conditioner provided by an embodiment of a first aspect of the present invention, the multi-split air conditioner comprises a plurality of outdoor units, at least two of the plurality of outdoor units are arranged from high to low in height direction, and the control method comprises:

[0007] When it is determined that the defrosting condition is met, the operating state of each outdoor fan is obtained, and whether the corresponding outdoor unit is frosted is determined according to the operating state of each outdoor fan and a predetermined frosting determination condition;

[0008] When all of the outdoor units are frosted, the plurality of outdoor units are controlled to be defrosted in sequence from high to low positions.

[0009] According to an embodiment of the present invention, the step of controlling the plurality of outdoor units to defrost in sequence from high to low positions specifically includes:

[0010] The corresponding outdoor unit is sequentially made to enter the defrosting state and the remaining outdoor units are made to enter the non-defrosting state in the order from high to low positions, and after the corresponding outdoor unit completes defrosting, the outdoor unit at the next height position is switched to enter the defrosting state;

[0011] Among them, the opening of the electronic expansion valve of the outdoor unit in the defrost state is adjusted to a fully open opening; the opening of the electronic expansion valve of the outdoor unit in the non-defrost state is adjusted to a target opening, and the target opening is smaller than the normal operating opening of the corresponding outdoor unit; defrosting is completed when the coil temperature of the outdoor unit in the defrost state is greater than a preset temperature condition.

[0012] According to an embodiment of the present invention, the step of determining whether the defrosting condition is satisfied specifically includes:

[0013] Get the outdoor ambient temperature and the coil temperature of each outdoor unit;

[0014] Determining a defrost temperature according to the outdoor ambient temperature and a predetermined temperature determination relationship, and determining that the corresponding outdoor unit has a risk of frosting when the coil temperature is lower than the defrost temperature;

[0015] When all of the outdoor units have a risk of frost, it is determined that the defrosting condition is met.

[0016] According to an embodiment of the present invention, the step of determining the defrost temperature according to the outdoor ambient temperature and a predetermined temperature determination relationship specifically includes:

[0017] When the outdoor environment temperature is greater than or equal to the first temperature, the defrosting temperature is the first defrosting temperature;

[0018] When the outdoor environment temperature is between the first temperature and the second temperature, the defrosting temperature is the second defrosting temperature;

[0019] When the outdoor environment temperature is between the second temperature and the third temperature, the defrosting temperature is the third defrosting temperature;

[0020] When the outdoor environment temperature is lower than the third temperature, the defrosting temperature is the fourth defrosting temperature;

[0021] Among them, the first temperature, the second temperature, the third temperature, and the fourth temperature decrease in sequence, and the first defrost temperature, the second defrost temperature, the third defrost temperature, and the fourth defrost temperature decrease in sequence.

[0022] According to one embodiment of the present invention, when the outdoor ambient temperature is between the second temperature and the third temperature, a first relationship is satisfied between the outdoor ambient temperature and the defrosting temperature;

[0023] When the outdoor ambient temperature is lower than the third temperature, a second relationship is satisfied between the outdoor ambient temperature and the defrosting temperature.

[0024] According to one embodiment of the present invention, the step of obtaining the operating status of each outdoor fan and determining whether the corresponding outdoor unit is frosted according to the operating status of each outdoor fan and a predetermined frosting determination condition specifically includes:

[0025] Acquire a current rotation speed of the outdoor fan and a current operating current of the outdoor fan, and determine a theoretical operating current of the outdoor fan in a frost-free layer according to the current rotation speed and a predetermined first corresponding relationship;

[0026] Calculating a current ratio between the current operating current and the theoretical operating current;

[0027] When the current ratio is less than a first preset ratio, determining that the corresponding outdoor heat exchanger is frosted;

[0028] When the current ratio is between the first preset ratio and 1, it is determined that the corresponding outdoor heat exchanger is not frosted.

[0029] According to one embodiment of the present invention, the step of obtaining the operating status of each outdoor fan and determining whether the corresponding outdoor unit is frosted according to the operating status of each outdoor fan and a predetermined frosting determination condition specifically includes:

[0030] Acquire a current rotation speed of the outdoor fan and a current operating current of the outdoor fan, and determine a theoretical rotation speed of the outdoor fan in a frost-free layer according to the current operating current and a predetermined second corresponding relationship;

[0031] Calculating a speed ratio between the theoretical speed and the current speed;

[0032] When the speed ratio is less than a second preset ratio, determining that the corresponding outdoor heat exchanger is frosted;

[0033] When the speed ratio is between the second preset ratio and 1, it is determined that the corresponding outdoor heat exchanger is not frosted.

[0034] According to one embodiment of the present invention, the step of controlling the plurality of outdoor units to defrost in sequence from high to low positions further comprises:

[0035] Obtaining the coil temperature of each of the outdoor units;

[0036] When the coil temperature of each of the outdoor units is greater than or equal to a preset temperature threshold, the multi-split air conditioner is controlled to exit the defrosting program.

[0037] According to a second aspect of the present invention, a defrost control device for a multi-split air conditioner is provided, comprising:

[0038] An acquisition module, used for acquiring the operating state of each outdoor fan when it is determined that the defrosting condition is met, and determining whether the corresponding outdoor unit is frosted according to the operating state of each outdoor fan and a predetermined frosting determination condition;

[0039] The control module is used to control the plurality of outdoor units to defrost in sequence from high to low positions when all the outdoor units are frosted.

[0040] A multi-split air conditioner provided in accordance with an embodiment of the third aspect of the present invention comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps of the defrost control method provided in accordance with the embodiment of the first aspect of the present invention are implemented.

[0041] The above one or more technical solutions in the present invention have at least one of the following technical effects:

[0042] According to the defrost control method of the multi-split air conditioner provided by the embodiment of the present invention, the method comprises: when it is determined that the defrost condition is met, the operating state of each outdoor fan is obtained, and whether the corresponding outdoor unit is frosted is determined according to the operating state of each outdoor fan and the predetermined frosting judgment condition; when all the outdoor units are frosted, the plurality of outdoor units are controlled to be defrosted in sequence from high to low. When the multi-split air conditioner meets the defrost condition, the plurality of outdoor units are controlled to be defrosted in sequence from high to low, and the heat of the defrost water when the outdoor unit at a higher position is defrosted is used to melt the frost layer at a lower position, thereby reducing the energy consumption of the outdoor unit at a lower position when defrosting, and reducing the user's use cost. At the same time, the defrost water can effectively improve the fluidity of the surface of the outdoor heat exchanger during the flow process, thereby avoiding the situation where ice cubes are stuck between the fins of the heat exchanger and causing incomplete defrosting, and improving the defrosting effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the drawings required for use in the embodiments or related technical descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0044] Figure 1One of the flow charts of the defrost control method of a multi-split air conditioner provided in an embodiment of the present invention;

[0045] Figure 2 A second flowchart of the defrost control method for a multi-split air conditioner provided by an embodiment of the present invention;

[0046] Figure 3 A schematic structural diagram of a defrost control device for a multi-split air conditioner provided by an embodiment of the present invention;

[0047] Figure 4 A schematic structural diagram of a multi-split air conditioner provided in an embodiment of the present invention.

[0048] Reference numerals:

[0049] 301, acquisition module; 302, control module. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical solution and advantages of the invention clearer, the technical solution in the invention will be clearly described below in conjunction with the drawings in the invention. Obviously, the described embodiments are part of the embodiments of the invention, not all of the embodiments. Based on the embodiments in the invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the invention.

[0051] In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limitations on the embodiments of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0052] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0053] In the embodiments of the present invention, unless otherwise clearly specified and limited, the first feature being "above" or "below" the second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0054] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0055] In the related art, due to the large size of the heat exchanger of the multi-split outdoor unit, multiple outdoor heat exchangers are often installed in parallel to save space, and the refrigerant flow and refrigerant pressure of each outdoor unit are controlled by multiple electronic expansion valves, thereby realizing the flow control of the whole machine. When defrosting multiple outdoor units of the multi-split air conditioner, if multiple outdoor heat exchangers are defrosted at the same time, the energy consumption is large, which increases the user's cost of use.

[0056] The multi-split air conditioner involved in the embodiment of the present invention includes multiple outdoor units, which are arranged in parallel. In order to reduce the space occupied by the outdoor units, at least two of the multiple outdoor units are arranged from high to low in the height direction, that is, they are fixed by multi-layer brackets and occupy the projection area of ​​one outdoor unit on the ground.

[0057] In some cases, multiple outdoor units are installed on a multi-layer rack, for example, four outdoor units are installed on a four-layer rack, and the order from high to low refers to the order along the fourth layer, the third layer, the second layer to the first layer.

[0058] In some cases, multiple outdoor units are installed on two multi-layer racks, for example, four outdoor units are installed on two two-layer racks, and the order from high to low refers to the order from the second layer to the first layer. When multiple racks are used, each rack independently determines the high and low positions and control logic, and does not interfere with each other.

[0059] According to the first aspect of the present invention, the defrosting control method of the multi-split air conditioner is provided. Figure 1 ,include:

[0060] S100. When it is determined that the defrosting condition is met, the operating state of each outdoor fan is obtained, and whether the corresponding outdoor unit is frosted is determined according to the operating state of each outdoor fan and a predetermined frosting determination condition.

[0061] It is understandable that when the external ambient temperature and the coil temperature of the outdoor unit meet a certain relationship, it can be determined that the defrosting conditions are met, and at this time, the outdoor heat exchanger of the outdoor unit has the possibility of frosting. Secondly, when the outdoor heat exchanger has the risk of frosting, it is necessary to further verify whether the outdoor unit is frosted; when the outdoor unit is frosted, the operating state of the outdoor fan will change, and the frost layer will block the position between the coil and the fin of the outdoor heat exchanger. When the outdoor fan rotates, it does less work on the air and has less wind resistance. At this time, the corresponding working current and wind speed of the outdoor fan will change, so it can be indirectly reflected whether the outdoor unit is frosted based on this part of the change.

[0062] S110: When all outdoor units are frosted, control the plurality of outdoor units to be defrosted in order from high to low positions.

[0063] It is understandable that when the multi-split air conditioner meets the defrosting conditions, multiple outdoor units are controlled to be defrosted in order from high to low, and the heat of the defrosting water of the outdoor units at higher positions is used to melt the frost layer at lower positions, thereby reducing the energy consumption of the outdoor units at lower positions during defrosting and reducing the user's usage cost. At the same time, the defrosting water can effectively improve the fluidity of the surface of the outdoor heat exchanger during the flow process, thereby preventing ice from getting stuck between the fins of the heat exchanger and causing incomplete defrosting, and improving the defrosting effect.

[0064] In some embodiments, the step of controlling the plurality of outdoor units to defrost in sequence from high to low positions specifically includes:

[0065] S111. Make the corresponding outdoor units enter the defrost state and the remaining outdoor units enter the non-defrost state in order from high to low positions, and switch the outdoor units at the next height position to the defrost state after the corresponding outdoor units complete defrosting; wherein, the opening of the electronic expansion valve of the outdoor unit in the defrost state is adjusted to a fully open opening; the opening of the electronic expansion valve of the outdoor unit in the non-defrost state is adjusted to a target opening, and the target opening is smaller than the normal operating opening of the corresponding outdoor unit; defrosting is completed when the coil temperature of the outdoor unit in the defrost state is greater than the preset temperature condition.

[0066] It is understandable that when multiple layers of outdoor units are installed on the same bracket, the opening of the electronic expansion valve of the outdoor unit in the defrosting state is adjusted to the fully open opening, and the high-temperature refrigerant from the indoor heat exchanger is directly introduced into the outdoor heat exchanger of the outdoor unit, which can quickly increase the temperature of the outdoor heat exchanger and thus achieve efficient defrosting. The electronic expansion valves of the remaining outdoor units are adjusted to the target opening, such as zero opening, and the refrigerant in the refrigerant main pipe all flows to the outdoor unit in the defrosting state, which improves the defrosting efficiency and minimizes the interference with the indoor heat exchanger.

[0067] In order to explain its working principle, this embodiment takes a two-layer outdoor unit as an example:

[0068] When the defrosting conditions are met, the whole machine enters defrosting control. After the four-way valve is turned, the electronic expansion valves of the upper and lower outdoor units are controlled as follows:

[0069] First, when entering the defrosting condition, the electronic expansion valve of the upper outdoor unit is opened from the current valve step to 470pls (full-open step number, here only takes the full-open 470pls as an example, the 470pls mentioned in the article is not limited, when the full-open step number of the electronic expansion valve is 2000pls, it is opened to 2000pls here), and the electronic expansion valve of the lower outdoor unit is closed from the current valve step to 0pls, and this state is maintained until the heat exchanger coil temperature of the upper outdoor unit is greater than 10°C. During the process, since the refrigerant flows through the outdoor heat exchanger of the upper outdoor unit in a concentrated manner, the outdoor heat exchanger of the upper outdoor unit can melt the frost layer on the surface of the heat exchanger in a short time, and the moisture formed by the melting of the frost layer can flow downward along the heat exchanger fins, and when the heat exchanger coil temperature is greater than 10°C, it can be judged that there is no frost layer attached to the heat exchanger of the upper outdoor unit.

[0070] Secondly, when the defrosting of the heat exchanger of the upper outdoor unit is completed, the electronic expansion valves of the upper and lower outdoor units are controlled as follows: the electronic expansion valve of the upper outdoor unit is closed from 470pls to 0pls, and the electronic expansion valve of the lower outdoor unit is opened from 0pls to 470pls. During this process, the water formed by the defrosting of the heat exchanger of the upper outdoor unit will continue to flow downward and exchange heat with the frost layer formed by the lower heat exchanger. At the same time, the refrigerant of the main pipe is concentrated in the lower heat exchanger, and the lower heat exchanger is quickly exchanged with heat. When the coil temperature of the lower outdoor unit is greater than 10℃, it can be judged that there is no frost layer attached to the heat exchanger of the lower outdoor unit.

[0071] Furthermore, when the coil temperature of the lower outdoor unit is greater than 10°C, in order to prevent the refrigerant from accumulating in the outdoor unit heat exchanger module, the electronic expansion valves of the upper and lower outdoor units are all opened, that is, the electronic expansion valve of the upper outdoor unit is opened from 0pls to 470pls, and the electronic expansion valve of the lower outdoor unit remains unchanged at 470pls until the conditions for exiting defrosting are met.

[0072] In some embodiments, the step of determining that the defrosting condition is met specifically includes:

[0073] Get the outdoor ambient temperature and the coil temperature of each outdoor unit.

[0074] The defrost temperature is determined according to the outdoor ambient temperature and a predetermined temperature determination relationship, and when the coil temperature is lower than the defrost temperature, it is determined that the corresponding outdoor unit has a risk of frosting.

[0075] When all outdoor units have the risk of frost, it is determined that the defrosting conditions are met.

[0076] It is understandable that the risk of frost formation of the coil is different at different outdoor ambient temperatures, so the defrost temperature can be determined based on the outdoor ambient temperature and the predetermined temperature judgment relationship, with the defrost temperature as the judgment standard; if the coil temperature is higher than the corresponding defrost temperature, it means that the risk of frost formation of the coil is small or it is determined that there is no frost risk; if the coil temperature is lower than the corresponding defrost temperature, it means that the risk of frost formation of the coil is large or it is determined that there is a frost risk. When all the outdoor unit coils have a frost risk, it is determined that the defrost conditions are met.

[0077] In some embodiments, the step of determining the defrost temperature according to the outdoor ambient temperature and a predetermined temperature determination relationship specifically includes:

[0078] When the outdoor ambient temperature is greater than or equal to the first temperature, the defrost temperature is the first defrost temperature;

[0079] When the outdoor ambient temperature is between the first temperature and the second temperature, the defrosting temperature is the second defrosting temperature;

[0080] When the outdoor ambient temperature is between the second temperature and the third temperature, the defrosting temperature is the third defrosting temperature;

[0081] When the outdoor ambient temperature is lower than the third temperature, the defrosting temperature is the fourth defrosting temperature;

[0082] Among them, the first temperature, the second temperature, the third temperature and the fourth temperature decrease in sequence, and the first defrost temperature, the second defrost temperature, the third defrost temperature and the fourth defrost temperature decrease in sequence.

[0083] It is understandable that as the outdoor ambient temperature decreases, the corresponding defrost temperature also becomes lower, and the risk of coil frost increases. The following example illustrates:

[0084] When the outdoor ambient temperature is ≥10℃, it is not easy to frost because the outdoor ambient temperature is high. The temperature judgment value for entering defrost is -3℃, that is, the defrost temperature is -3℃;

[0085] When 10℃>outdoor ambient temperature≥0℃, the defrost temperature is -6℃;

[0086] When 0℃>outdoor ambient temperature≥-5℃, the defrost temperature is the outdoor ambient temperature minus 6℃;

[0087] When the outdoor ambient temperature is less than -5℃, the defrost temperature is the outdoor ambient temperature minus 6℃, or the defrost temperature is a fixed value of -20℃. Either of the two temperature conditions for entering defrost can be met.

[0088] In some embodiments, when the outdoor ambient temperature is between the second temperature and the third temperature, a first relationship is satisfied between the outdoor ambient temperature and the defrost temperature, for example, the defrost temperature is the outdoor ambient temperature minus 6°C; when the outdoor ambient temperature is less than the third temperature, a second relationship is satisfied between the outdoor ambient temperature and the defrost temperature, for example, the defrost temperature is the outdoor ambient temperature minus 6°C;

[0089] Among them, the first relationship and the second relationship are both positively correlated with humidity. When the humidity is higher, the difference between the defrost temperature and the outdoor ambient temperature is smaller, that is, the defrost temperature is higher; for example, when the humidity increases, the defrost temperature is the outdoor ambient temperature minus 3°C.

[0090] In some embodiments, the step of obtaining the operating status of each outdoor fan and determining whether the corresponding outdoor fan is frosted according to the operating status of each outdoor fan and a predetermined frosting determination condition specifically includes:

[0091] S101. Obtain a current rotation speed of an outdoor fan and a current operating current of the outdoor fan, and determine a theoretical operating current of the outdoor fan in a frost-free layer according to the current rotation speed and a predetermined first corresponding relationship.

[0092] S102, calculating the current ratio between the current working current and the theoretical working current.

[0093] S1031. When the current ratio is less than a first preset ratio, determine that the corresponding outdoor heat exchanger is frosted.

[0094] S1032: When the current ratio is between the first preset ratio and 1, determine that the corresponding outdoor heat exchanger is not frosted.

[0095] See also Figure 2When the coil of the outdoor unit is frosted, the frost layer will block the gap between the coil and the fin, thus affecting the air flow. For the outdoor fan, the interaction between the fan blades and the air is reduced at the same speed, the wind resistance is reduced, and the current working current of the outdoor fan to maintain the current speed is reduced. Therefore, by comparing the current working current with the theoretical working current of the outdoor unit when there is no frost layer (obtained and stored in advance through experiments), the condensation of the frost layer can be determined. The more severe the frosting, the smaller the wind resistance of the outdoor fan, and the smaller the current working current, that is, an indirect relationship between the current working current and the thickness of the frost layer is established.

[0096] Calculate the current ratio of the current working current to the theoretical working current. When the current ratio is less than the first preset ratio, it means that the thickness of the frost layer between the outdoor unit coil and the fin has reached a certain level, which may affect the heat exchange of the outdoor heat exchanger. Defrosting is required. When the current ratio is large, such as close to or equal to 1, it means that there is no frost on the outdoor unit coil, and the current operating state can be maintained without defrosting. In order to avoid the influence of external wind speed on frost determination, the first preset ratio can be 0.9, allowing for a small range of fluctuations.

[0097] In some embodiments, the step of obtaining the operating status of each outdoor fan and determining whether the corresponding outdoor fan is frosted according to the operating status of each outdoor fan and a predetermined frosting determination condition specifically includes:

[0098] S104, obtaining a current rotation speed of the outdoor fan and a current operating current of the outdoor fan, and determining a theoretical rotation speed of the outdoor fan in a frost-free layer according to the current operating current and a predetermined second corresponding relationship.

[0099] S105: Calculate the speed ratio between the theoretical speed and the current speed.

[0100] S1061. When the speed ratio is less than a second preset ratio, it is determined that the corresponding outdoor heat exchanger is frosted.

[0101] S1062: When the speed ratio is between the second preset ratio and 1, it is determined that the corresponding outdoor heat exchanger is not frosted.

[0102] It is understandable that when the coil of the outdoor unit is frosted, the frost layer will block the gap between the coil and the fin, thereby affecting the flow of air. For the outdoor fan, the interaction between the fan blades and the air is reduced at the same speed, the wind resistance is reduced, and the current working current of the outdoor fan to maintain the current speed is reduced. Under the current current working current, the theoretical speed of the outdoor fan when there is no frost layer can be determined according to the second corresponding relationship. The theoretical speed should be less than the current speed. According to the speed ratio between the theoretical speed and the current speed, the interference of the frost layer thickness between the outdoor unit coils on the wind speed can be determined. When the speed ratio is less than the second preset ratio, it means that the frost layer thickness has a greater interference with the wind speed, and it is determined that the corresponding outdoor heat exchanger is frosted and needs to be defrosted as soon as possible. When the speed ratio is between the second preset ratio and 1, it means that the frost layer has a smaller interference with the wind speed, or there is no frost layer, so it is determined that the corresponding outdoor heat exchanger is not frosted.

[0103] In some embodiments, the step of controlling the plurality of outdoor units to defrost in order from high to low positions further comprises:

[0104] Get the coil temperature of each outdoor unit.

[0105] When the coil temperature of each outdoor unit is greater than or equal to the preset temperature threshold, the multi-split air conditioner is controlled to exit the defrosting program.

[0106] It can be understood that after the outdoor units are defrosted in order from high to low, all the refrigerant in the main pipe is introduced into the bottom outdoor unit, and the temperature of other outdoor units will rise due to the closure of the electronic expansion valves, and the heat transfer of the refrigerant. When the coil temperatures of all outdoor units are greater than or equal to the preset temperature threshold, it can be proved that there will be no frost layer on the outdoor unit coil, and therefore a signal can be sent to control the multi-split air conditioner to exit the defrost program.

[0107] In the embodiment of the present invention, when the electronic device controlling the multi-split air conditioner performs an action, the controller sends a corresponding control signal, and the corresponding electronic device adjusts its own operating state according to the electronic control signal.

[0108] According to the second aspect of the present invention, the defrost control device of the multi-split air conditioner is provided. Figure 3 ,include:

[0109] The acquisition module 301 is used to acquire the operating status of each outdoor fan when it is determined that the defrosting condition is met, and determine whether the corresponding outdoor fan is frosted according to the operating status of each outdoor fan and a predetermined frosting judgment condition.

[0110] The control module 302 is used to control the plurality of outdoor units to defrost in sequence from high to low positions when all the outdoor units are frosted.

[0111] It should be noted that the above steps S100 to S110, as well as other steps, are only for the convenience of description and do not constitute a time sequence limitation for each step in the defrost control method of a multi-split air conditioner. In addition, some contents are described in detail in the defrost control method of a multi-split air conditioner provided in the first aspect embodiment, and all contents in the defrost control method of a multi-split air conditioner are also applicable to the defrost control device of a multi-split air conditioner provided in the second aspect embodiment, and in order to avoid repetition, the defrost control device of a multi-split air conditioner provided in the second aspect embodiment is not described in detail. Similarly, the contents in the above two aspects of the embodiments can be used to explain the contents of all the following aspects of the embodiments, so the repeated contents will not be repeated in the following embodiments. The defrost control device of a multi-split air conditioner provided in accordance with the embodiment of the present invention has a technical effect corresponding to the technical effect of the above-mentioned defrost control method of a multi-split air conditioner, and will not be repeated here.

[0112] A multi-split air conditioner provided in accordance with an embodiment of the third aspect of the present invention comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps of the defrost control method for the multi-split air conditioner provided in accordance with the embodiment of the first aspect of the present invention are implemented.

[0113] Figure 4 The physical structure diagram of an electronic device of a multi-split air conditioner is illustrated, and the electronic device may include: a processor (processor) 810, a communication interface (Communications Interface) 820, a memory (memory) 830 and a communication bus 840, wherein the processor 810, the communication interface 820, and the memory 830 complete mutual communication through the communication bus 840. The processor 810 can call the logic instructions in the memory 830 to execute the defrosting control method of the multi-split air conditioner, and the method includes: when it is determined that the defrosting condition is met, the operating state of each outdoor fan is obtained, and the corresponding outdoor unit is determined whether it is frosted according to the operating state of each outdoor fan and the predetermined frosting judgment condition. When all the outdoor units are frosted, the multiple outdoor units are controlled to be defrosted in sequence from high to low positions.

[0114] In addition, the logic instructions in the above-mentioned memory 830 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0115] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0116] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method 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 this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for 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.

[0117] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A defrosting control method for a multi-split air conditioner, characterized in that: The multi-split air conditioner includes a plurality of outdoor units, at least two of which are arranged from high to low in height direction, and the control method includes: When it is determined that the defrosting condition is met, the operating state of each outdoor fan is obtained, and whether the corresponding outdoor unit is frosted is determined according to the operating state of each outdoor fan and a predetermined frosting determination condition; When all of the outdoor units are frosted, the plurality of outdoor units are controlled to be defrosted in sequence from high to low positions.

2. The defrosting control method of a multi-split air conditioner according to claim 1, characterized in that: The step of controlling the plurality of outdoor units to defrost in sequence from high to low positions specifically includes: The corresponding outdoor unit is sequentially made to enter the defrosting state and the remaining outdoor units are made to enter the non-defrosting state in the order from high to low positions, and after the corresponding outdoor unit completes defrosting, the outdoor unit at the next height position is switched to enter the defrosting state; Among them, the opening of the electronic expansion valve of the outdoor unit in the defrost state is adjusted to a fully open opening; the opening of the electronic expansion valve of the outdoor unit in the non-defrost state is adjusted to a target opening, and the target opening is smaller than the normal operating opening of the corresponding outdoor unit; defrosting is completed when the coil temperature of the outdoor unit in the defrost state is greater than a preset temperature condition.

3. The defrosting control method of a multi-split air conditioner according to claim 1, characterized in that: The steps to determine the defrosting conditions include: Obtaining the outdoor ambient temperature and the coil temperature of each of the outdoor units; Determining a defrost temperature according to the outdoor ambient temperature and a predetermined temperature determination relationship, and determining that the corresponding outdoor unit has a risk of frosting when the coil temperature is lower than the defrost temperature; When all of the outdoor units have a risk of frost, it is determined that the defrosting condition is met.

4. The defrosting control method of a multi-split air conditioner according to claim 3, characterized in that: The step of determining the defrost temperature according to the outdoor ambient temperature and a predetermined temperature determination relationship specifically includes: When the outdoor environment temperature is greater than or equal to the first temperature, the defrosting temperature is the first defrosting temperature; When the outdoor environment temperature is between the first temperature and the second temperature, the defrosting temperature is the second defrosting temperature; When the outdoor environment temperature is between the second temperature and the third temperature, the defrosting temperature is the third defrosting temperature; When the outdoor environment temperature is lower than the third temperature, the defrosting temperature is the fourth defrosting temperature; Among them, the first temperature, the second temperature, and the third temperature decrease in sequence, and the first defrosting temperature, the second defrosting temperature, the third defrosting temperature, and the fourth defrosting temperature decrease in sequence.

5. The defrosting control method of a multi-split air conditioner according to claim 4, characterized in that: When the outdoor ambient temperature is between the second temperature and the third temperature, a first relationship is satisfied between the outdoor ambient temperature and the defrosting temperature; When the outdoor ambient temperature is lower than the third temperature, a second relationship is satisfied between the outdoor ambient temperature and the defrosting temperature.

6. The defrosting control method of a multi-split air conditioner according to any one of claims 1 to 5, characterized in that: The step of obtaining the operating status of each outdoor fan and determining whether the corresponding outdoor fan is frosted according to the operating status of each outdoor fan and a predetermined frosting determination condition specifically includes: Acquire a current rotation speed and a current operating current of the outdoor fan, and determine a theoretical operating current of the outdoor fan in a frost-free layer according to the current rotation speed and a predetermined first corresponding relationship; Calculating a current ratio between the current operating current and the theoretical operating current; When the current ratio is less than a first preset ratio, determining that the corresponding outdoor heat exchanger is frosted; When the current ratio is between the first preset ratio and 1, it is determined that the corresponding outdoor heat exchanger is not frosted.

7. The defrosting control method of a multi-split air conditioner according to any one of claims 1 to 5, characterized in that: The step of obtaining the operating status of each outdoor fan and determining whether the corresponding outdoor fan is frosted according to the operating status of each outdoor fan and a predetermined frosting determination condition specifically includes: Acquire the current speed and current working current of the outdoor fan, and determine the theoretical speed of the outdoor fan in a frost-free layer according to the current working current and a predetermined second corresponding relationship; Calculating a speed ratio between the theoretical speed and the current speed; When the speed ratio is less than a second preset ratio, determining that the corresponding outdoor heat exchanger is frosted; When the speed ratio is between the second preset ratio and 1, it is determined that the corresponding outdoor heat exchanger is not frosted.

8. The defrost control method for a multi-split air conditioner according to any one of claims 1 to 5, characterized in that: The step of controlling the plurality of outdoor units to defrost in sequence from high to low positions further comprises: Obtaining the coil temperature of each of the outdoor units; When the coil temperature of each of the outdoor units is greater than or equal to a preset temperature threshold, the multi-split air conditioner is controlled to exit the defrosting program.

9. A defrost control device for a multi-split air conditioner, characterized in that: include: An acquisition module, used for acquiring the operating state of each outdoor fan when it is determined that the defrosting condition is met, and determining whether the corresponding outdoor unit is frosted according to the operating state of each outdoor fan and a predetermined frosting determination condition; The control module is used to control the plurality of outdoor units to defrost in sequence from high to low positions when all the outdoor units are frosted.

10. A multi-split air conditioner, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the steps of the defrost control method for a multi-split air conditioner as described in any one of claims 1 to 8 are implemented.

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