Air conditioner

Abstract

The air conditioner comprises an indoor unit, and the indoor unit comprises an alternating current interface, a rectification module, a sampling module and a control module; the alternating current interface is used for accessing alternating current; the rectifier module is connected with the alternating current interface, rectifies the accessed alternating current and outputs bus voltage; the sampling module is connected with the rectification module and is used for sampling bus voltage to obtain sampling data; the control module is connected with the sampling module and receives sampling data; the control module is provided with a sampling period and a time difference threshold value; acquiring sample data, wherein the sample data at least comprises sampling data of the last sampling period of the sampling time; acquiring a ripple signal of the sample data and moments of the last peak and the last trough as a first moment and a second moment; calculating a difference between the second moment and the first moment, and recording the difference as a time difference; the control module compares the time difference with a time difference threshold value and judges whether the indoor unit is powered off or not according to the comparison result. The power-off judgment speed and accuracy of the indoor unit are improved, and the cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioning, and particularly to an air conditioner. Background Art

[0002] A multi-connected air conditioner unit generally consists of one or several outdoor units connected to several direct expansion indoor units of different or the same type and capacity, forming a single refrigeration cycle system, which has the characteristic of occupying less space and is widely used in fields such as residences, commercial centers, and public buildings.

[0003] When some of the indoor units connected to the outdoor unit are powered off, in order to avoid faults of the multi-connected air conditioner unit caused by the electronic expansion valve not being fully closed, it is necessary to use the electric energy charged by the electrolytic capacitor to close the electronic expansion valve at the moment when the indoor unit is powered off. Therefore, quickly determining the power-off of the indoor unit is a necessary condition for closing the electronic expansion valve.

[0004] Currently, indoor units generally use the alternating current output by the power grid for power supply. The rated voltage output by the power grid is not constant and there will be fluctuations. In addition, when high-power products start at the user end of the power grid, the input voltage of the indoor unit will also fluctuate. Indoor units generally have a function of collecting bus voltage for low-voltage protection. In the case of low voltage, the electronic expansion valve does not need to be closed. Therefore, how to quickly and correctly identify the power-off and low-voltage states is a prerequisite for whether the electronic expansion valve is closed and is also a technical problem in the industry.

[0005] The existing technology for determining the power-off or low-voltage state of an air conditioner unit has a complex determination process, which reduces the determination speed, and there are also problems of high cost and inaccurate identification.

[0006] The above information disclosed in this background art is only used to increase the understanding of the background art of this application. Therefore, it may include prior art that is not known to those of ordinary skill in the art. Summary of the Invention

[0007] Aiming at the problems of slow determination speed, high cost, and inaccuracy in determining the power-off of the indoor unit in the background art, the present invention provides an air conditioner, which improves the speed and accuracy of determining the power-off of the indoor unit and reduces the cost.

[0008] To achieve the above-mentioned invention purpose, the present invention adopts the following technical solutions:

[0009] An air conditioner, including an indoor unit, which includes an alternating current interface, a rectification module, a sampling module, and a control module;

[0010] The alternating current interface is used to access alternating current;

[0011] The rectification module is connected to the alternating current interface and rectifies the accessed alternating current to output a bus voltage;

[0012] The sampling module is connected to the rectification module and is used to sample the bus voltage to obtain sampling data;

[0013] The control module is connected to the sampling module and receives the sampling data; the control module is set with a sampling period and a time difference threshold; sample data is obtained, which at least includes the sampling data of the last sampling period of the sampling time; a ripple signal of the sample data is obtained; the moments of the last peak and valley of the ripple signal are respectively obtained and recorded as the first moment and the second moment; the second moment is later than the first moment; the difference between the second moment and the first moment is calculated and recorded as the time difference; the control module compares the time difference with the time difference threshold and determines whether the indoor unit is powered off according to the comparison result.

[0014] According to some specific embodiments of the present application, the control module sets the sampling period as the period of the alternating current frequency.

[0015] According to some specific embodiments of the present application, a high-pass filter module is configured in the control module, and its cut-off frequency is not greater than the frequency of the alternating current;

[0016] The control module performs high-pass filtering processing on the sample data to obtain the ripple signal.

[0017] According to some specific embodiments of the present application, the sampling frequency of the sampling module configured in the control module is greater than twice the frequency of the alternating current.

[0018] According to some specific embodiments of the present application, the sampling frequency of the sampling module configured in the control module is 250 Hz.

[0019] According to some specific embodiments of the present application, when the first moment is the moment of the peak of the ripple signal, the second moment is the moment of the valley of the ripple signal or the cut-off moment of the ripple signal;

[0020] When the first moment is the moment of the valley of the ripple signal, the second moment is the moment of the peak of the ripple signal or the cut-off moment of the ripple signal.

[0021] According to some specific embodiments of the present application, when the sampling time reaches or first exceeds the duration of the sampling period, the control module first processes the sample data to obtain the ripple signal, obtains the time difference included in the ripple signal, compares the time difference with the time difference threshold, and determines whether the indoor unit is powered off.

[0022] According to some specific embodiments of the present application, when the sampling time reaches or exceeds the duration of the sampling period, for each additional sampling data received by the control module, the control module processes the sample data once to obtain the ripple signal, obtains the time difference included in the ripple signal, compares the time difference with the time difference threshold, and determines whether the indoor unit is powered off.

[0023] According to some specific embodiments of the present application, the time difference threshold includes a first time difference threshold;

[0024] The control module compares the time difference with the first time difference threshold; if the time difference reaches or exceeds the first time difference threshold, the control module determines that the indoor unit is powered off; if the time difference reaches or is less than the first time difference threshold, the control module determines that the indoor unit is normally powered.

[0025] According to some specific embodiments of the present application, the time difference threshold further includes a second time difference threshold, which is less than the first time difference threshold;

[0026] The control module compares the time difference with the first time difference threshold; when the control module determines that the indoor unit is normally powered, it compares the time difference with the second time difference threshold;

[0027] If the time difference is between the second time difference threshold and the first time difference threshold, the control module determines that the supply voltage of the indoor unit fluctuates abnormally;

[0028] If the time difference reaches or is less than the second time difference threshold, the control module determines that the indoor unit is stably powered.

[0029] The air conditioner of the present invention processes the sampling data of the bus voltage of the sampling module received by the control module to obtain a ripple signal, compares the time difference included in the ripple signal with the time difference threshold, and determines whether the indoor unit is powered off or there is an abnormal supply voltage situation according to the comparison result, without increasing hardware resources and without causing an increase in cost; processing the sampling data of at least one sampling period as sample data for processing and judgment basis, with relatively high processing and judgment efficiency, improving the efficiency and accuracy of determining whether the indoor unit is powered off or there is an abnormal supply voltage situation, solving the problem of difficult judgment of power off and low voltage, ensuring the closing of the electronic expansion valve of the indoor unit during power off, and improving the stability and reliability of the operation of the air conditioning system.

[0030] After reading the specific embodiments of the present invention in conjunction with the accompanying drawings, other features and advantages of the present invention will become clearer. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0032] Figure 1 Schematic diagram of the connection of components of an air conditioner according to an embodiment;

[0033] Figure 2 Schematic diagram of the process for judging the power supply state of the indoor unit of an air conditioner according to an embodiment;

[0034] Figure 3 Schematic diagram of the process for judging the power supply state of the indoor unit of an air conditioner according to an embodiment;

[0035] Figure 4 Schematic diagram of the process for judging the power supply state of the indoor unit of an air conditioner according to an embodiment;

[0036] Figure 5 Schematic diagram of the process for judging the power supply state of the indoor unit of an air conditioner according to an embodiment;

[0037] Figure 6 Schematic diagram of the process for judging the power supply state of the indoor unit of an air conditioner according to an embodiment;

[0038] Figure 7 Schematic diagram of the process for judging the power supply state of the indoor unit of an air conditioner according to an embodiment;

[0039] Figure 8 Schematic diagram of the process for judging the power supply state of the indoor unit of an air conditioner according to an embodiment;

[0040] Figure 9 Schematic diagram of the process for judging the power supply state of the indoor unit of an air conditioner according to an embodiment;

[0041] Figure 10 Schematic diagram of the waveform of the ripple signal of the normal power supply sample data according to an embodiment;

[0042] Figure 11 Schematic diagram of the waveform of the ripple signal of the abnormal power supply voltage fluctuation sample data according to an embodiment;

[0043] Figure 12 Schematic diagram of the waveform of the ripple signal of the power-off sample data according to an embodiment;

[0044] Figure 13 Schematic diagram of the waveform of the voltage amplitude corresponding to the frequency of the normal power supply sample data according to an embodiment;

[0045] Figure 14 Schematic diagram of the waveform of the frequency corresponding to the voltage amplitude of the abnormal power supply voltage fluctuation sample data according to the embodiment;

[0046] Figure 15 Schematic diagram of the waveform of the frequency corresponding to the voltage amplitude of the power failure sample data according to the embodiment;

[0047] Figure 16 Schematic diagram of the waveform including the sampling data when the abnormal power supply voltage occurs according to the embodiment;

[0048] Figure 17 Schematic diagram of the waveform including the sampling data when the power failure occurs according to the embodiment. Detailed implementation manners

[0049] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0050] The terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, unless otherwise stated, the meaning of "a plurality" is two or more.

[0051] In the description of the present application, it should be noted that unless otherwise clearly defined and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0052] The following disclosure provides many different embodiments or examples for implementing different structures of the present invention. To simplify the disclosure of the present invention, components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numerals and / or reference letters in different examples. This repetition is for the purpose of simplification and clarity and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0053]

Principle of Air Conditioner

[0054] An air conditioner performs a refrigeration cycle by using a compressor, a condenser, an expansion valve, and an evaporator. The refrigeration cycle includes a series of processes involving compression, condensation, expansion, and evaporation to cool or heat an indoor space.

[0055] The low-temperature and low-pressure refrigerant enters the compressor, and the compressor compresses it into a refrigerant gas in a high-temperature and high-pressure state and discharges the compressed refrigerant gas. The discharged refrigerant gas flows into the condenser. The condenser condenses the compressed refrigerant into a liquid phase, and heat is released to the surrounding environment through the condensation process.

[0056] The expansion valve expands the high-temperature and high-pressure liquid-phase refrigerant formed by condensation in the condenser into a low-pressure liquid-phase refrigerant. The evaporator evaporates the refrigerant expanded in the expansion valve and returns the refrigerant gas in a low-temperature and low-pressure state to the compressor. The evaporator can achieve a refrigeration effect by using the latent heat of evaporation of the refrigerant for heat exchange with the material to be cooled.

[0057] The outdoor unit of an air conditioner refers to the part of the refrigeration cycle including the compressor and the outdoor heat exchanger. The indoor unit of the air conditioner includes an indoor heat exchanger, and the expansion valve can be provided in the indoor unit or the outdoor unit.

[0058] The indoor heat exchanger and the outdoor heat exchanger serve as condensers or evaporators. When the indoor heat exchanger serves as a condenser, the outdoor heat exchanger serves as an evaporator, and the air conditioner serves as a heater in the heating mode; when the indoor heat exchanger serves as an evaporator, the outdoor heat exchanger serves as a condenser, and the air conditioner serves as a cooler in the cooling mode.

[0059]

Principle of Multi-Split Air Conditioning Unit

[0060] A multi-split air conditioning unit includes one or more outdoor units and a plurality of indoor units that are connected by a refrigerant link and electrically communicated with the outdoor unit; each indoor unit can be a direct expansion type indoor unit of the same or different forms and capacities.

[0061] An electronic expansion valve is provided in each indoor unit, which is used to open and connect the refrigerant when the indoor unit is turned on, and to close and cut off the refrigerant when the indoor unit is turned off.

[0062]

Air conditioner

[0063] Refer to Figure 1 , Figure 2 , Figure 3 As shown in

[0064] , the air conditioner of the present invention includes an indoor unit, which includes an AC power interface 1, a rectification module 2, a sampling module 3, and a control module 4.

[0065] The AC power interface 1 is used to access AC power; the AC power is an external AC power supply, and is accessed by the AC power interface 1 to supply power to the indoor unit.

[0066] The rectification module 2 includes a full-wave rectification circuit structure, is connected to the AC power interface 1, and is used to perform full-wave rectification processing on the AC power accessed by the AC power interface 1 and then output a bus voltage, which is a DC signal and is connected to the indoor unit bus; the DC signal of the bus voltage contains ripples with a frequency equal to the frequency of the AC power and twice the frequency of the AC power.

[0067] The sampling module 3 is connected to the rectification module 2 and is used to continuously sample the bus voltage multiple times to obtain multiple sampling data.

[0068] The control module 4 is connected to the sampling module 3 and is used to receive the sampling data. The control module 4 is provided with a sampling period and a time difference threshold S11, and obtains sample data S2; the sample data is at least a combination of the sampling data of the last sampling period in the sampling time. That is, the sampling module 3 continuously collects the sampling data of the bus voltage; the control module 4 receives each sampling data; the sampling time may be multiple complete sampling periods or multiple complete sampling periods and some incomplete sampling periods; when the sampling time is an incomplete sampling period, the sample data at least includes a combination of the sampling data of one complete sampling period calculated forward from the last moment of the sampling time.

[0069] Perform filtering processing on the sample data to obtain the ripple signal S3 of the sample data; extract the moments S41 of the last wave peak and wave valley of the ripple signal, and record them as the first moment and the second moment respectively; the second moment is later than the first moment; subtract the first moment from the second moment S5 and record it as the time difference; that is, the time difference is equal to the difference between the second moment and the first moment; that is, the time difference is the time difference between the last wave peak and the last wave valley of the ripple signal; that is, the time difference is the duration of the signal continuation from the last wave peak to the last wave valley of the ripple signal.

[0070] The air conditioner of the present invention receives the sampled data of the bus voltage collected by the sampling module 3 through the control module 4, and filters it to obtain the ripple signal of the sample data; obtains the time difference included in the ripple signal, compares the obtained time difference with the time difference threshold, and judges whether the indoor unit is powered off according to the comparison result, without increasing hardware resources and without causing an increase in the cost of the indoor unit; uses each sampled data within the sampling period as the sample data for processing and judgment basis, with multiple data volumes and low data volumes, improving the efficiency of data processing and the accuracy of judging whether the indoor unit is powered off, ensuring the accuracy and reliability of controlling the closing of the electronic expansion valve of the indoor unit when powered off, and further improving the stability and reliability of the operation of the air conditioner system.

[0071] In some specific embodiments, referring to Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 ,the time difference threshold includes a first time difference threshold. The control module 4 compares the time difference with the first time difference threshold S6; if the time difference reaches or exceeds the first time difference threshold S7, the control module 4 judges that the indoor unit is powered off S8; if the time difference reaches or is less than the first time difference threshold, the control module 4 determines that the indoor unit is normally powered S9.

[0072] The air conditioner of this embodiment can determine whether the indoor unit is powered off through a single comparison of the time difference with the first time difference threshold, improving the efficiency of judging whether the indoor unit is powered off, saving time for using the charging electric energy of the electrolytic capacitor to supply power to the control module 4 to control the closing of the electronic expansion valve of the indoor unit, ensuring that more of the charging electric energy of the electrolytic capacitor is applied to the control module 4 to control the closing of the electronic expansion valve, and improving the reliability of controlling the closing of the electronic expansion valve when the indoor unit is powered off.

[0073] In some specific embodiments, referring to Figure 1 、 Figure 2 、 Figure 3 ,the time difference threshold further includes a second time difference threshold, which is less than the first time difference threshold.

[0074] When the control module 4 determines that the indoor unit is normally powered, it compares the time difference with the second time difference threshold S10; if the time difference reaches or exceeds the second time difference threshold, the control module 4 determines that the supply voltage of the indoor unit fluctuates abnormally S92, but it can still provide the voltage for the normal operation of the indoor unit; that is, when the time difference is between the second time difference threshold and the first time difference threshold, the control module 4 determines that the supply voltage of the indoor unit fluctuates abnormally S92, and the indoor unit operates normally without controlling the closing of its electronic expansion valve. If the time difference reaches or is less than the second time difference threshold, the control module 4 determines that the indoor unit is supplied with stable voltage S91.

[0075] The air conditioner of this embodiment further determines the power supply situation when the indoor unit is powered normally by configuring a second time difference threshold to find out whether there is abnormal fluctuation in the power supply voltage of the indoor unit, and grasps the situation of the AC power supply of the indoor unit, including whether the alternating current itself is stable or whether there are high-power electrical appliances with frequent startups around the indoor unit. It can be used as a basis for judging whether to add additional protection and preventive measures, and extend the service life and operation reliability of the air conditioner.

[0076] In some specific embodiments, referring to Figure 1 , Figure 2 , Figure 3 , the indoor unit includes a circuit board; an AC interface 1, a rectification module 2, a sampling module 3, and a control module 4 are all arranged on the circuit board.

[0077] In some specific embodiments, referring to Figure 1 , Figure 2 , Figure 3 , a high-pass filter module is configured in the control module 4, and its cut-off frequency is not greater than the frequency of the alternating current, which is used to perform high-pass filtering on the sample data to obtain a ripple signal.

[0078] In some specific embodiments, referring to Figure 1 , Figure 2 , Figure 3 , the sampling frequency of the sampling module 3 configured in the control module 4 is greater than twice the frequency of the alternating current, which ensures that the ripple signal of the sample data appears aliased and distorted, affecting the accuracy of the time difference, and further affecting the judgment result of the power supply state of the indoor unit judged according to it.

[0079] In addition, by setting the sampling frequency to be greater than twice the frequency of the alternating current, the air conditioner of this embodiment enables the ripples with frequencies of the alternating current frequency and twice the alternating current frequency contained in the bus voltage to be retained, which is used to extract the time difference between the moments of its last wave peak and last wave valley, ensuring the reliability and accuracy of the judgment on whether the indoor unit is powered off.

[0080] In some specific embodiments, referring to Figure 1 , Figure 2 , Figure 3 , the sampling frequency of the sampling module 3 configured in the control module 4 is 250 Hz.

[0081] In some specific embodiments, referring to Figure 1 , Figure 2 , Figure 3 , when the indoor unit starts to run, the sampling module 3 starts sampling immediately, and the control module 4 receives the sampling data immediately.

[0082] When the sampling time reaches the duration of the sampling period, the control module 4 performs high-pass filtering on the sample data for the first time, and also obtains the time difference for the first time, compares the time difference with the time difference threshold, and determines the power supply state of the indoor unit.

[0083] That is, when the sampling time does not reach the duration of the sampling period, the control module 4 does not perform high-pass filtering on the sample data, and determines the power supply state of the indoor unit by comparing the time difference with the time difference threshold.

[0084] In some specific embodiments, referring to Figure 1 、 Figure 2 、 Figure 3 When the sampling time reaches the duration of the sampling period, for each additional sampling data received by the control module 4, high-pass filtering is performed on the latest sample data, the time difference is obtained, the time difference is compared with the time difference threshold, and it is determined whether the indoor unit is powered off.

[0085] In some specific embodiments, referring to Figure 1 、 Figure 2 、 Figure 3 Since the frequency of the ripple signal includes the AC frequency and twice the AC frequency, and the sample data is sampling data with a non-fixed sampling period; the relative positions of the last peak and valley of the ripple signal are uncertain.

[0086] And due to the abnormal fluctuation of the power supply voltage and the influence of power-off, the ripple signal may only include one peak or valley.

[0087] Therefore, when the first moment is the peak moment of the ripple signal, the second moment is the valley moment of the ripple signal or the cut-off moment of the ripple signal; when the first moment is the valley moment of the ripple signal, the second moment is the peak moment of the ripple signal or the cut-off moment of the ripple signal.

[0088] The following illustrates the embodiments of the present invention through specific examples. Referring to Figure 10 、 Figure 11 、 Figure 12 The indoor unit is powered by connecting to the AC interface 1 with 220V, 50Hz AC power. The sampling frequency of the sampling module 3 for collecting the bus voltage is 250Hz; high-pass filtering is performed on the last six sampling data (more than the five sampling data collected in one sampling period) of the sampling; the cut-off frequency of the high-pass filtering is selected as 20Hz; of course, 30Hz or 40Hz can also be selected. The first time difference threshold and the second time difference threshold are set to 0.01 s and 0.006s respectively.

[0089] Figure 10 、 Figure 11 、 Figure 12Waveform schematic diagrams of the ripple signals of the sample data during regulated power supply, abnormal voltage fluctuations, and power outages respectively; the time differences are Δt1 = 0.004 s; Δt2 = 0.008 s; Δt3 = 0.012 s respectively. Since Δt1 is less than the second time difference threshold, it is determined as regulated power supply; since Δt2 is between the second time difference threshold and the first time difference threshold, it is determined as abnormal voltage fluctuations of the power supply; since Δt3 is greater than the first time difference threshold, it is determined as a power outage.

[0090] Of course, the setting of the first time difference threshold and the second time difference threshold is determined according to factors including at least the parameters of the alternating current.

[0091] Refer to Figure 1 、 Figure 4 、 Figure 5 The present invention also discloses an air conditioner, which includes an alternating current interface 1, a rectification module 2, a sampling module 3, and a control module 4 connected in sequence; the alternating current module is used to access the alternating current for powering the indoor unit.

[0092] The rectification module 2 includes all rectification circuit structures, performs full-wave rectification on the accessed alternating current and then outputs the bus voltage, which is a DC signal and is connected to the indoor unit bus; the sampling module 3 continuously samples the bus voltage multiple times to obtain a plurality of sampling data; the control module 4 receives each sampling data.

[0093] The control module 4 is provided with a sampling period and a voltage amplitude threshold S14; obtains sample data S2, which is a combination of each sampling data in the last complete sampling period during the sampling time; the control module 4 processes the sample data to obtain the voltage amplitudes S20 at different frequencies; and then obtains the maximum value S30 of each voltage amplitude.

[0094] That is, during the sampling process of the sampling module 3, the sampling time may be a complete sampling period or include multiple complete sampling periods and partial sampling periods; when the sampling time contains an incomplete sampling period, the sample data is a combination of each sampling data included in a complete sampling period calculated forward from the last moment of the sampling time.

[0095] The control module 4 compares the maximum amplitude with the voltage amplitude threshold, and determines whether the indoor unit is powered off according to the comparison result.

[0096] The air conditioner of the present invention processes each sampling data of the bus voltage collected by the sampling module 3 through the control module 4, compares the maximum amplitude value obtained after processing with the voltage amplitude threshold, and determines whether the indoor unit is powered off according to the comparison result, without adding hardware resources and without causing an increase in cost; uses the sampling data within the latest sampling period as sample data for processing and judgment basis, and the data is a small number of multiple data, improving the processing efficiency and the accuracy of the judgment of whether the power is off, ensuring the accuracy and reliability of controlling the closing of the electronic expansion valve of the indoor unit when the power is off, and further improving the stability and reliability of the operation of the air conditioner system.

[0097] In some specific embodiments, referring to Figure 1 、 Figure 4 、 Figure 5 , the voltage amplitude threshold includes a first voltage amplitude threshold.

[0098] The control module 4 compares the maximum amplitude value with the first voltage amplitude threshold S40; if the maximum amplitude value reaches or exceeds the first voltage amplitude threshold S50, the control module 4 determines that the indoor unit is normally powered S9; if the maximum amplitude value reaches or is less than the first voltage amplitude threshold, the control module 4 determines that the indoor unit is powered off S8.

[0099] The air conditioner of this embodiment can determine whether the indoor unit is powered off by comparing the maximum amplitude value with the first voltage amplitude threshold once, improving the efficiency of the judgment of whether the indoor unit is powered off, and gaining more time for using the charging electric energy of the electrolytic capacitor to supply power to the control module 4 to control the closing of the electronic expansion valve of the indoor unit, ensuring that more of the charging electric energy of the electrolytic capacitor is applied to the control module 4 to control the closing of the electronic expansion valve, and improving the reliability of controlling the closing of the electronic expansion valve when the indoor unit is powered off.

[0100] In some specific embodiments, referring to Figure 1 、 Figure 4 、 Figure 5 , the voltage amplitude threshold further includes a second voltage amplitude threshold, which is greater than the first voltage amplitude threshold.

[0101] When the control module 4 determines that the indoor unit is normally powered S9, it compares the maximum amplitude value with the second voltage amplitude threshold.

[0102] If the maximum amplitude value reaches or is less than the second voltage amplitude threshold, that is, if the maximum amplitude value is between the first voltage amplitude threshold and the second voltage amplitude threshold S90, the control module 4 determines that the supply voltage of the indoor unit has abnormal fluctuations S92.

[0103] If the maximum amplitude value reaches or exceeds the second voltage amplitude threshold, the control module 4 determines that the indoor unit has regulated power supply S91.

[0104] The air conditioner in this embodiment further determines the power supply situation when the indoor unit is normally powered by configuring a second voltage amplitude threshold, so as to know whether there is abnormal fluctuation of the power supply voltage in the indoor unit, and master the situation of the AC power supply of the indoor unit, including whether the AC power itself is stable and whether there are high-power electrical appliances with frequent startups around the indoor unit. It can be used as a judgment basis for whether to add additional protection and preventive measures, and extend the service life and operation reliability of the air conditioner.

[0105] In some specific embodiments, referring to Figure 1 、 Figure 4 、 Figure 5 , the sampling frequency of the sampling module 3 configured in the control module 4 is greater than twice the frequency of the alternating current.

[0106] In some specific embodiments, the sampling frequency of the sampling module 3 configured in the control module 4 is 250 Hz. In some specific embodiments, the control module 4 is configured with a Fourier transform module, which obtains complex numbers with the same number as the sampling data in the sample data through Fourier transform processing of the latest sample data; calculates the voltage amplitude of each complex number at its frequency through amplitude.

[0107] Specifically,

[0108] V_f = fft(V(i,…,i+M-1))

[0109] In the formula:

[0110] V_f is a complex number array;

[0111] i is the sampling data serial number;

[0112] V(i,…,i+M-1) is an array of the i-th to the i+M-1-th sampling data;

[0113] M is the number of sampling data collected within a sampling period.

[0114] The voltage amplitude A of the sample data at different frequencies is calculated by the following formula:

[0115] A(1,…,M) = abs(V_f).

[0116] In some specific embodiments, referring to Figure 1 、 Figure 4 、 Figure 5 , the control module 4 uses the comparison method to obtain the maximum value among the voltage amplitudes, that is, the maximum amplitude value.

[0117] In some specific embodiments, referring to Figure 1 、 Figure 4 、 Figure 5, when the indoor unit starts to run, the sampling module 3 starts sampling, and the control module 4 starts receiving the sampling data.

[0118] When the sampling time reaches the duration of the sampling period, the control module 4 first processes the sample data to obtain the voltage amplitudes at different frequencies, obtains the maximum amplitude value, compares the maximum amplitude value with the voltage amplitude threshold, and determines the power supply state of the indoor unit according to the comparison result.

[0119] In some specific embodiments, referring to Figure 1 , Figure 4 , Figure 5 , when the sampling time reaches the duration of the sampling period, for each additional sampling data received by the control module 4, a Fourier transform of the latest sample data is performed, the maximum amplitude value is obtained, the maximum amplitude value is compared with the voltage amplitude threshold, and a judgment is made on whether the indoor unit is powered off.

[0120] The following illustrates the embodiments of the present invention through specific examples. Referring to Figure 13 , Figure 14 , Figure 15 , the indoor unit is powered by connecting an AC power supply of 220V, 50Hz to the AC power interface 1 and accessing the indoor unit. The sampling frequency of the sampling module 3 for collecting the bus voltage is 250Hz; Fourier transforms and voltage amplitude calculations are performed on the last five sampling data of the sampling. The first voltage amplitude threshold and the second voltage amplitude threshold are set to 1395 and 1440 respectively.

[0121] Figure 13 , Figure 14 , Figure 15 are the frequency - amplitude waveform schematic diagrams of the sample data during regulated power supply, abnormal voltage fluctuation, and power failure respectively; the maximum amplitude values are Amax1 = 1447; Amax2 = 1405; Amax3 = 1386 respectively. Since Amax1 is greater than the second voltage amplitude threshold, it is determined as regulated power supply; Amax2 is between the first voltage amplitude threshold and the second voltage amplitude threshold, it is determined as abnormal voltage fluctuation of the power supply; Amax3 is less than the first voltage amplitude threshold, it is determined as power failure. Of course, the setting of the first voltage amplitude threshold and the second voltage amplitude threshold is determined according to factors including at least the parameters of the alternating current.

[0122] In some specific embodiments, referring to Figure 1 , Figure 6 , the control module 4 is set with a sampling period, a time difference threshold, and a voltage amplitude threshold S12.

[0123] The control module 4 obtains the sample data S2, which is a combination of the sampling data of the last complete sampling period in the sampling time.

[0124] Perform high-pass filtering on the sample data to obtain the ripple signal S3; extract the moments of the last peak and the last trough of the ripple signal, and denote them as the first moment and the second moment S4 respectively; the second moment is later than the first moment; calculate the difference between the second moment and the first moment to obtain the time difference S5.

[0125] The control module 4 compares the time difference with the time difference threshold S6; if the time difference reaches or exceeds the time difference threshold S7, it is determined that the indoor unit is powered off S8; if the time difference reaches or is less than the time difference threshold, it is determined that the indoor unit is powered normally S9.

[0126] At this time, the time difference threshold is actually equal to the first time difference threshold in the above embodiment.

[0127] When the control module 4 determines that the indoor unit is powered normally S9, perform Fourier transform and amplitude calculation on the sample data to obtain the voltage amplitudes at different frequencies S20, and obtain the maximum value of each voltage amplitude S30 through the comparison method, that is, obtain the maximum amplitude value.

[0128] The control module 4 compares the maximum amplitude value with the voltage amplitude threshold S40; if the maximum amplitude value reaches or is less than the voltage amplitude threshold S50, the control module 4 determines that the power supply voltage of the indoor unit fluctuates abnormally S92.

[0129] If the maximum amplitude value reaches or exceeds the voltage amplitude threshold, the control module 4 determines that the indoor unit is supplied with stable voltage S91.

[0130] At this time, the voltage amplitude threshold is actually equal to the second voltage amplitude threshold in the above embodiment.

[0131] In some specific embodiments, referring to Figure 1 、 Figure 7 ,the control module 4 is set with a sampling period, a time difference threshold, and a voltage amplitude threshold S12.

[0132] The control module 4 obtains the sample data S2, which is a combination of the sampling data of the last complete sampling period in the sampling time.

[0133] Perform Fourier transform and amplitude calculation at different frequencies on the sample data to obtain the voltage amplitudes at different frequencies S20, and obtain the maximum value of each voltage amplitude S30 through the comparison method, that is, obtain the maximum amplitude value.

[0134] The control module 4 compares the maximum amplitude value with the voltage amplitude threshold; if the maximum amplitude value reaches or exceeds the voltage amplitude threshold S40, the control module 4 determines that the indoor unit is powered normally S9.

[0135] If the maximum amplitude value reaches or is less than the voltage amplitude threshold, the control module 4 determines that the indoor unit is powered off S8.

[0136] At this time, the voltage amplitude threshold is actually equal to the first voltage amplitude threshold in the above embodiments.

[0137] When the control module 4 determines that the power supply of the indoor unit is normal S9, it performs high-pass filtering on the sample data to obtain the ripple signal S3 of the sample data; extracts the moments of the last peak and the last valley of the ripple signal, and respectively records them as the first moment and the second moment S4; the second moment is later than the first moment; calculates the second moment minus the first moment to obtain the time difference S5.

[0138] The control module 4 compares the time difference with the time difference threshold; if the time difference reaches or exceeds the time difference threshold S7, it determines that the power supply voltage of the indoor unit fluctuates abnormally S92; if the time difference reaches or is less than the time difference threshold, it determines that the indoor unit has a regulated power supply S91.

[0139] At this time, the time difference threshold is actually equal to the second time difference threshold in the above embodiments.

[0140] Refer to Figure 1 、 Figure 8 The present invention also discloses an air conditioner, which includes an AC power interface 1, a rectification module 2, a sampling module 3, and a control module 4 connected in sequence.

[0141] The AC power interface 1 is used to connect the indoor unit to AC power and supply power to the indoor unit. The rectification module 2 includes a full-wave rectification circuit structure and is used to rectify the connected AC power and output the bus voltage, which is a DC signal and is connected to the indoor unit bus; the sampling module 3 is used to collect the bus voltage to obtain sampling data; the control module 4 receives the sampling data.

[0142] The control module 4 sets the time difference threshold, obtains the voltage threshold S13 and the sample data S2; the sample data is a combination of sampling data obtained from the latest continuous multiple samplings; calculates the average value of each sampling data of the sample data and records it as the average voltage S60; the control module 4 compares the average voltage with the voltage threshold S70; and determines whether the power supply of the indoor unit is abnormal according to the comparison result.

[0143] If the control module 4 determines that the power supply of the indoor unit is abnormal S81, the control module 4 performs filtering on the sample data to obtain a ripple signal, S3 and obtains the moments of the last peak and the last valley of the ripple signal, which are respectively recorded as the first moment and the second moment S4; the second moment is later than the first moment; the difference between the second moment and the first moment is recorded as the time difference S5; compares the time difference with the time difference threshold S6, and determines whether the abnormal power supply of the indoor unit is a power cut according to the comparison result.

[0144] The air conditioner of the present invention calculates the average voltage from the sample data composed of multiple sampling data, compares the average voltage with the voltage threshold, and determines whether the power supply of the indoor unit is abnormal according to the comparison result; when there is a power supply abnormality, that is, when there may be a power outage or abnormal voltage fluctuation in the power supply, the sample data is processed to obtain its ripple signal, and then the time difference included in the ripple signal is obtained, and the time difference is compared with the time difference threshold and further determines whether the power supply abnormality of the indoor unit is a power outage of the indoor unit or an abnormal voltage fluctuation of the power supply of the indoor unit, and finally decides whether to control the closing of the electronic expansion valve of the indoor unit, solves the problem that it is difficult to judge the power outage of the indoor unit and the low-voltage power supply, improves the accuracy and efficiency of judging the power supply abnormality of the indoor unit as a power outage or low voltage, improves the reliability and efficiency of control without increasing costs, and further improves the reliability of the operation of the air conditioner system.

[0145] In some specific embodiments, referring to Figure 1 、 Figure 8 , the control module 4 compares the average voltage with the voltage threshold S70; if the average voltage reaches or exceeds the voltage threshold S80, the control module 4 determines that the indoor unit has a regulated power supply S91; if the average voltage reaches or is lower than the voltage threshold, the control module 4 determines that the power supply of the indoor unit is abnormal S81.

[0146] In some specific embodiments, when the control module 4 determines that the power supply of the indoor unit is abnormal S81, it obtains the time difference of the sample data and compares the time difference with the time difference threshold; if the time difference reaches or exceeds the time difference threshold, the control module 4 determines that the indoor unit is powered off S8; if the time difference reaches or is less than the time difference threshold S7, the control module 4 determines that the power supply voltage of the indoor unit has an abnormal fluctuation S92.

[0147] At this time, the time difference threshold is actually equal to the first time difference threshold in the above embodiment.

[0148] In some specific embodiments, referring to Figure 1 、 Figure 8 , the control module 4 sets the sampling period, which is the period of the alternating current frequency. That is, if the alternating current frequency is F, the sampling period is 1 / F.

[0149] When the sampling time does not exceed the duration of the sampling period, the sample data is the combination of each sampling data within the entire sampling time; when the sampling time exceeds the duration of the sampling period, the sample data is the combination of each sampling data in the last complete sampling period during the sampling time.

[0150] In some specific embodiments, referring to Figure 1 、 Figure 8When the sampling time has not reached the duration of the sampling period, the voltage threshold adopts the constant value configured in the control module 4, that is, the value determined by manual setting; when the sampling time reaches or exceeds the duration of the sampling period, calculate the average value and standard deviation of each sampling data in the first sampling period of the sampling time; the voltage threshold is equal to the value obtained by calculating the difference between the average value of each sampling data in the first sampling period of the sampling time and the product of the standard deviation of each sampling data in the first sampling period of the sampling time and the coefficient.

[0151] That is, the voltage threshold can also be obtained through the following calculation.

[0152] The sampling period is the period 1 / F of the frequency of the alternating current; the sampling frequency is f; then the number of samplings M within one sampling period is calculated by the following formula.

[0153] M = round(f / F);

[0154] In the formula,

[0155] f is the sampling frequency;

[0156] F is the frequency of the alternating current;

[0157] Round is the rounding operation.

[0158] Sampling is performed when the indoor unit starts to operate; when the number of samplings is less than M, the control module 4 uses the voltage threshold of the constant value configured therein; when the number of samplings reaches or exceeds M, calculate the average value and standard deviation of each sampling data in the first sampling period of the sampling time, and calculate the voltage threshold.

[0159] Specifically,

[0160] V_t = V_m - 0.5×V_s(1)

[0161]

[0162]

[0163] In the formula:

[0164] V_t is the voltage threshold;

[0165] V_m is the average value of each sampling data in the first sampling period;

[0166] V_s is the standard deviation of each sampling data in the first sampling period;

[0167] The coefficient of the standard deviation is 0.5.

[0168] In some specific embodiments, refer to Figure 1 , Figure 8When the indoor unit starts to operate, for each additional sampling data received by the control module 4, the acquisition of the average voltage, the comparison between the average voltage and the voltage threshold, and the judgment of whether the power supply of the indoor unit is abnormal are carried out once.

[0169] In some specific embodiments, referring to Figure 1 、 Figure 8 the control module 4 is configured with a high-pass filter module to perform high-pass filtering on the sample data of abnormal power supply to obtain its ripple signal and the time difference included in the ripple signal.

[0170] In some specific embodiments, referring to Figure 1 、 Figure 8 the sampling frequency is not less than 2 times the alternating current frequency.

[0171] The embodiments of the present invention will be described below through specific examples. Referring to Figure 16 、 Figure 17 the indoor unit is powered by connecting to the alternating current interface 1 with 220V, 50Hz alternating current. The sampling frequency of the sampling module 3 for collecting the bus voltage is 250Hz; the last five sampling data of the sampling form the sample data.

[0172] Figure 16 、 Figure 17 are respectively waveform diagrams of sampling data including abnormal voltage fluctuations and power outages; the voltage threshold is 286.4V; when the average voltage of the sampling data reaches or exceeds the voltage threshold, the indoor unit supplies power stably; when the average voltage reaches or is less than the voltage threshold, the power supply is abnormal.

[0173] Referring to Figure 1 、 Figure 9 the present invention also discloses an air conditioner, which includes an alternating current interface 1, a rectification module 2, a sampling module 3, and a control module 4 connected in sequence.

[0174] The alternating current interface 1 is used to connect the alternating current to the indoor unit to supply power to the indoor unit. The rectification module 2 includes a full-wave rectification circuit structure, which is used to rectify the connected alternating current and output the bus voltage, which is a DC signal and is connected to the indoor unit bus; the sampling module 3 is used to collect the bus voltage to obtain sampling data; the control module 4 receives the sampling data.

[0175] The control module 4 sets the voltage amplitude threshold, obtains the voltage threshold S13 and the sample data S2; the sample data is a combination of sampling data obtained by the latest continuous multiple samplings; calculates the average value S60 of each sampling data of the sample data, denoted as the average voltage; the control module 4 compares the average voltage with the voltage threshold S70; judges whether the power supply of the indoor unit is abnormal according to the comparison result.

[0176] If the control module 4 determines that the power supply of the indoor unit is abnormal (S81), the control module 4 obtains the voltage amplitudes at different frequencies of the sample data (S20), and obtains the maximum value of the voltage amplitudes (S30); compares the maximum amplitude value with the voltage amplitude threshold (S40), and determines whether the abnormal power supply of the indoor unit is a power cut according to the comparison result.

[0177] The air conditioner of the present invention calculates the average voltage from the sample data composed of multiple sampling data, compares the average voltage with the voltage threshold, and determines whether the power supply of the indoor unit is abnormal according to the comparison result; when there is an abnormal power supply, that is, when there may be a power cut or abnormal voltage fluctuation in the power supply, the sample data is processed to obtain the maximum value of its amplitude, and the maximum amplitude value is compared with the voltage amplitude threshold and according to the comparison result, it is further determined whether the abnormal power supply of the indoor unit is a power cut of the indoor unit or an abnormal voltage fluctuation of the power supply of the indoor unit, and finally decides whether to control the closing of the electronic expansion valve of the indoor unit, solves the problem that it is difficult to judge the power cut and low-voltage power supply of the indoor unit, improves the accuracy and efficiency of judging the abnormal power supply of the indoor unit as a power cut or low voltage, improves the reliability and efficiency of control without increasing costs, and further improves the reliability of the operation of the air conditioner system.

[0178] In some specific embodiments, referring to Figure 1 、 Figure 9 , the control module 4 compares the average voltage with the voltage threshold (S70); if the average voltage reaches or exceeds the voltage threshold (S80), the control module 4 determines that the indoor unit has a regulated power supply (S91); if the average voltage reaches or is lower than the voltage threshold, the control module 4 determines that the power supply of the indoor unit is abnormal (S81).

[0179] In some specific embodiments, referring to Figure 1 、 Figure 9 , when the control module 4 determines that the power supply of the indoor unit is abnormal (S81), it obtains the maximum value of the amplitude of the sample data (S30) and compares the maximum value of the amplitude with the voltage amplitude threshold (S40); if the maximum value of the amplitude reaches or exceeds the voltage amplitude threshold (S50), the control module 4 determines that the power supply voltage of the indoor unit has an abnormal fluctuation (S92); if the maximum value of the amplitude reaches or is less than the voltage amplitude threshold, the control module 4 determines that the indoor unit has a power cut (S91).

[0180] In some specific embodiments, referring to Figure 1 、 Figure 9 , the control module 4 sets the sampling period, which is the period of the alternating current frequency. That is, if the alternating current frequency is F, the sampling period is 1 / F.

[0181] When the sampling time does not exceed the duration of the sampling period, the sample data is the combination of each sampling data within the entire sampling time; when the sampling time exceeds the duration of the sampling period, the sample data is the combination of each sampling data in the last complete sampling period during the sampling time.

[0182] In some specific embodiments, referring to Figure 1 , Figure 9 , when the sampling time does not reach the duration of the sampling period, the voltage threshold adopts the constant value configured in the control module 4, that is, the value determined by manual setting; when the sampling time reaches or exceeds the duration of the sampling period, calculate the average value and standard deviation of each sampling data in the first sampling period of the sampling time; the voltage threshold is equal to the value obtained by calculating the difference between the average value of each sampling data in the first sampling period of the sampling time and the product of the standard deviation of each sampling data in the first sampling period of the sampling time and a coefficient.

[0183] That is, the voltage threshold can also be obtained through the following calculation.

[0184] The sampling period is the period 1 / F of the frequency of the alternating current; the sampling frequency is f; then the number of samplings M within one sampling period is calculated by the following formula.

[0185] M = round(f / F);

[0186] In the formula,

[0187] f is the sampling frequency;

[0188] F is the frequency of the alternating current;

[0189] Round is the nearest integer operation.

[0190] Sampling is performed when the indoor unit starts to operate; when the number of samplings is less than M, the control module 4 uses the voltage threshold of the constant value configured therein; when the number of samplings reaches or exceeds M, calculate the average value and standard deviation of each sampling data in the first sampling period of the sampling time, and calculate the voltage threshold.

[0191] Specifically,

[0192] V_t = V_m - 0.5×V_s(1)

[0193]

[0194]

[0195] In the formula:

[0196] V_t is the voltage threshold;

[0197] V_m is the average value of each sampling data in the first sampling period;

[0198] V_s is the standard deviation of each sampling data in the first sampling period;

[0199] The coefficient of the standard deviation is 0.5.

[0200] In some specific embodiments, referring toFigure 1 , Figure 9 When the indoor unit starts to run, for each additional sampling data received by the control module 4, the acquisition of the average voltage, the comparison between the average voltage and the voltage threshold, and the judgment on whether the power supply of the indoor unit is abnormal are implemented once.

[0201] In some specific embodiments, referring to Figure 1 , Figure 9 , the control module 4 is configured with a Fourier transform module to perform Fourier transform on the latest sample data and calculate the amplitudes of each complex number to obtain the voltage amplitudes at different frequencies, and obtain the maximum value of each voltage amplitude, that is, the maximum amplitude value, through the comparison method.

[0202] In some specific embodiments, referring to Figure 1 , Figure 9 , the sampling frequency is not less than 2 times the alternating current frequency.

[0203] In the description of the above embodiments, the specific features, structures, materials or characteristics can be combined in a suitable manner in any one or more embodiments or examples.

[0204] The above are only the specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. An air conditioner, characterized in that, it includes an indoor unit, which includes an AC power interface, a rectification module, a sampling module, and a control module; the AC power interface is used to access AC power; the rectification module is connected to the AC power interface and rectifies the accessed AC power to output a bus voltage; the sampling module is connected to the rectification module and is used to sample the bus voltage to obtain sampling data; the control module is connected to the sampling module and receives the sampling data; the control module is set with a sampling period and a time difference threshold; obtain sample data, which at least includes the sampling data of the last sampling period of the sampling time; obtain the ripple signal of the sample data; respectively obtain the moments of the last peak and valley of the ripple signal, denoted as the first moment and the second moment; the second moment is later than the first moment; calculate the difference between the second moment and the first moment, denoted as the time difference; the control module compares the time difference with the time difference threshold and determines whether the indoor unit is powered off according to the comparison result.

2. The air conditioner according to claim 1, characterized in that, the control module sets the sampling period as the period of the AC power frequency.

3. The air conditioner according to claim 1, characterized in that, a high-pass filter module is configured in the control module, and its cut-off frequency is not greater than the frequency of the AC power; the control module performs high-pass filtering on the sample data to obtain the ripple signal.

4. The air conditioner according to claim 1, characterized in that, the sampling frequency of the sampling module configured in the control module is greater than twice the frequency of the AC power.

5. The air conditioner according to claim 4, characterized in that, the sampling frequency of the sampling module configured in the control module is 250 Hz.

6. The air conditioner according to claim 1, characterized in that, when the first moment is the moment of the peak of the ripple signal, the second moment is the moment of the valley of the ripple signal or the cut-off moment of the ripple signal; when the first moment is the moment of the valley of the ripple signal, the second moment is the moment of the peak of the ripple signal or the cut-off moment of the ripple signal.

7. The air conditioner according to claim 1, characterized in that, when the sampling time reaches or first exceeds the duration of the sampling period, the control module first processes the sample data to obtain the ripple signal, obtains the time difference included in the ripple signal, compares the time difference with the time difference threshold, and determines whether the indoor unit is powered off.

8. The air conditioner according to claim 7, characterized in that, when the sampling time reaches or exceeds the duration of the sampling period, for each additional sampling data received by the control module, it performs processing on the sample data to obtain the ripple signal, obtains the time difference included in the ripple signal, compares the time difference with the time difference threshold, and determines whether the indoor unit is powered off.

9. The air conditioner according to any one of claims 1 to 8, characterized in that, The time difference threshold includes a first time difference threshold; The control module compares the time difference with the first time difference threshold; if the time difference reaches or exceeds the first time difference threshold, the control module determines that the indoor unit is powered off; if the time difference reaches or is less than the first time difference threshold, the control module determines that the indoor unit is normally powered.

10. The air conditioner according to claim 9, wherein, the time difference threshold further includes a second time difference threshold, which is less than the first time difference threshold; the control module compares the time difference with the first time difference threshold; when the control module determines that the indoor unit is normally powered, it compares the time difference with the second time difference threshold; if the time difference is between the second time difference threshold and the first time difference threshold, the control module determines that the supply voltage of the indoor unit fluctuates abnormally; if the time difference reaches or is less than the second time difference threshold, the control module determines that the indoor unit is stably powered.

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