Photovoltaic air conditioner and oil return control method therefor

Abstract

Disclosed in the present invention are a photovoltaic air conditioner and an oil return control method therefor. The oil return control method comprises: acquiring an operating frequency of a compressor of a photovoltaic air conditioner during operation; when the duration of the operating frequency being less than a first frequency value reaches a first duration, performing photovoltaic multi-power peak scanning to obtain a maximum power value of a photovoltaic maximum power point; and when the maximum power value is less than an oil return power value, executing an oil return operation process. The present invention can be used to improve the reliability of oil return control of photovoltaic air conditioners.

Description

Photovoltaic air conditioning and its oil return control method Technical Field

[0001] This invention belongs to the field of energy-saving air conditioning technology, specifically, it relates to photovoltaic air conditioners and their oil return control methods. Background Technology

[0002] When an air conditioner is running, the compressor continuously circulates refrigerant oil and compressor oil through pipelines, allowing the compressor to be lubricated by the returned oil. If the compressor cannot return oil properly, it can easily lead to insufficient lubrication and increased wear, and in severe cases, it can even cause the compressor to seize up, affecting the normal operation of the compressor and the air conditioner. To solve the compressor oil return problem, existing technology usually determines that the air conditioner needs oil return control when the compressor's operating frequency is lower than the critical oil return frequency for a duration exceeding a preset time threshold.

[0003] Photovoltaic air conditioning, as an energy-saving type of air conditioner, has been widely applied in various fields such as production and daily life due to the increasing urgency of energy conservation and emission reduction needs and the continuous maturation of photovoltaic technology. Photovoltaic air conditioners utilize the photovoltaic array in the photovoltaic module to convert solar energy into electrical energy to provide the energy required for their operation. However, the output power of the photovoltaic array is greatly affected by the environment. If the photovoltaic array is shaded, not only will the maximum power of the photovoltaic array decrease, but multiple peak power points will also appear, affecting the stability of the photovoltaic array's power output. If the output power of the photovoltaic array cannot meet the target power of the air conditioner, in order to avoid the air conditioner from shutting down, the compressor is usually controlled to operate at a reduced frequency to maintain the operation of the air conditioner. The instability of the photovoltaic array's power output and the compressor's reduced frequency operation due to the low output power of the photovoltaic array reduce the reliability of traditional compressor oil return control, and may even lead to the inability to meet the oil return control conditions and thus prevent oil return, affecting the normal operation of the compressor and the photovoltaic air conditioner. Technical issues

[0004] One of the objectives of this invention is to provide a method for controlling the oil return of photovoltaic air conditioners, so as to improve the reliability of the oil return control of photovoltaic air conditioners. Technical solutions

[0005] To achieve the above-mentioned objectives, the present invention employs the following technical solution:

[0006] A photovoltaic air conditioning oil return control method, comprising:

[0007] Obtain the operating frequency of the compressor in the photovoltaic air conditioner;

[0008] When the duration of the operating frequency being less than the first frequency value reaches the first duration, a photovoltaic multi-power peak scan is performed to obtain the maximum power value of the photovoltaic maximum power point.

[0009] When the maximum power value is less than the oil return power value, an oil return operation process is performed.

[0010] In some embodiments of the present application, in the oil return operation process, an oil return operation frequency is determined according to the maximum power value, and the compressor is controlled to operate at the oil return operation frequency for a second duration.

[0011] In some embodiments of the present application, the method further comprises:

[0012] When the maximum power value is not less than the oil return power value, a real-time target operation power of the photovoltaic air conditioner is obtained;

[0013] When the maximum power value is less than the real-time target operation power, a first control mode is performed as follows:

[0014] A current real-time frequency of the compressor of the photovoltaic air conditioner is obtained, the current real-time frequency is reduced to obtain a current actual operation frequency;

[0015] According to a corresponding relationship between the actual operation frequency and an intermittent operation mode, a current intermittent operation mode corresponding to the current actual operation frequency is determined; the intermittent operation mode at least includes a continuous operation time and a shutdown time;

[0016] When the current actual operation frequency is less than a second frequency value, and an interval time from a previous oil return reaches an interval time threshold value, an oil return operation process is performed; the interval time threshold value is determined according to a continuous operation time in m consecutive intermittent operation modes.

[0017] In some embodiments of the present application, the first control mode further comprises:

[0018] It is judged whether the oil return operation process is successful;

[0019] If yes, the interval time is cleared and re-timed;

[0020] If no, the interval time continues to accumulate.

[0021] In some embodiments of the present application, the first control mode further comprises:

[0022] If the current actual operation frequency is not less than the second frequency value, and / or the interval time from the previous oil return does not reach the interval time threshold value, the photovoltaic air conditioner is controlled to operate according to the current actual operation frequency and the current intermittent operation mode.

[0023] In some embodiments of the present application, the method further comprises:

[0024] When the maximum power value is not less than the oil return power value and the maximum power value is not less than the current real-time running power, a second control mode is executed as follows:

[0025] The current real-time frequency of the compressor of the photovoltaic air conditioner is obtained, and when the duration that the current real-time frequency is less than the second frequency value reaches a third duration, an oil return running process is executed.

[0026] In some embodiments of the present application, the photovoltaic multi-power peak scanning is performed to obtain the photovoltaic maximum power point, specifically including:

[0027] On the photovoltaic power-voltage curve, a working point with a voltage of open circuit voltage is taken as an initial search point, and searching is performed in a direction of decreasing voltage, a first peak power point is searched, and a first voltage and a first power corresponding to the first peak power point are recorded.

[0028] A difference voltage is determined according to the first voltage; the difference voltage is less than the first voltage.

[0029] A working point with a voltage equal to the difference voltage is taken as a new search starting point to continue searching, a subsequent searched peak power point is recorded as a most recent peak power point, and a voltage and a power corresponding to the most recent peak power point are recorded.

[0030] A sum of the voltage corresponding to the most recent peak power point and the difference voltage is taken as a voltage of a next search starting point.

[0031] It is judged whether a difference between the first voltage and the voltage of the next search starting point is less than the difference voltage; if not, a working point with a voltage equal to the voltage of the next search starting point is taken as a new search starting point to continue searching; until the difference between the first voltage and the voltage of the next search starting point is less than the difference voltage, the searching is stopped.

[0032] After the searching is stopped, a point with a maximum power among all searched peak power points is determined as the photovoltaic maximum power point.

[0033] In some embodiments of the present application, the difference voltage is determined according to the first voltage, specifically including:

[0034] The number N of series-connected cell panels of the photovoltaic array is obtained, the difference voltage is determined according to the first voltage and the number N, and the difference voltage is positively correlated with the first voltage and negatively correlated with the number N.

[0035] Still another object of the present application is to provide a photovoltaic air conditioner, comprising an air conditioner body and a photovoltaic module, the air conditioner body comprising a compressor, and the photovoltaic air conditioner further comprising a controller configured to execute the photovoltaic air conditioner oil return control method.

[0036] Another object of the present application is to provide a computer readable storage medium, having stored thereon a computer program which, when executed by a processor, implements the photovoltaic air conditioner oil return control method described above. Advantages

[0037] Compared with the prior art, the advantages and positive effects of the present application are:

[0038] The photovoltaic air conditioner and its oil return control method provided by the present application, when the running frequency of the compressor during operation is less than the first frequency value for a duration of the first duration, will perform photovoltaic multi-power peak scanning to obtain the maximum power value of the photovoltaic maximum power point, and compare the maximum power value with the oil return power value. When the maximum power value is less than the oil return power value, oil return operation control will be performed. By using this control method, multi-power peak scanning is performed again under the condition of continuous low-frequency operation of the compressor, effectively avoiding the complexity of multi-power peak scanning under any working condition and the instability of air conditioner operation caused by inaccurate scanning. When the maximum power value obtained by scanning is less than the oil return power value, it indicates that the output power of the photovoltaic module is low, and then forced oil return control is performed to avoid the difficulty of normal oil return due to insufficient output power provided by the photovoltaic, improve the reliability of air conditioner oil return control, and further improve the operation stability of the photovoltaic air conditioner.

[0039] Other features and advantages of the present application will become more apparent after reading the detailed description of the application in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0041] Fig. 1 is a flowchart of one embodiment of the photovoltaic air conditioner oil return control method of the present application;

[0042] Fig. 2 is a flowchart of another embodiment of the photovoltaic air conditioner oil return control method of the present application. Embodiments of the present application

[0043] In order to make the purpose, technical solutions and advantages of the present application more clear, the present application will be further described in detail below in conjunction with the drawings and embodiments.

[0044] It should be explained that the technical solutions among various embodiments of the present application can be combined with each other, but it must be based on that a person skilled in the art can realize, when the combination of the technical solutions appears contradictory or unachievable, it should be considered that the combination of the technical solutions does not exist, and is not within the protection scope required by the present application.

[0045] Fig. 1 shows a flow chart of one embodiment of the present application photovoltaic air conditioner oil return control method. In this embodiment, the photovoltaic air conditioner includes an air conditioner body and a photovoltaic module, the air conditioner body includes a compressor, and the photovoltaic module provides power for the operation of the air conditioner body.

[0046] As shown in Fig. 1, the photovoltaic air conditioner of this embodiment uses the following method for oil return control.

[0047] S11: Obtain the operating frequency of the compressor of the photovoltaic air conditioner when the compressor is working.

[0048] S12: When the duration of the operating frequency being less than the first frequency value reaches the first duration, perform photovoltaic multi-power peak scanning to obtain the maximum power value of the photovoltaic maximum power point.

[0049] While obtaining the operating frequency of the compressor when the compressor is working, the working time of each operating frequency is also recorded. When the operating frequency is obtained in step S11, the duration of the compressor working at this operating frequency can also be obtained at the same time.

[0050] Compare the operating frequency obtained in step S11 with the first frequency value, and at the same time, compare the duration of the operating frequency with the first duration. If the duration of the operating frequency being less than the first frequency value reaches the first duration, perform photovoltaic multi-power peak scanning to obtain the maximum power value corresponding to the photovoltaic maximum power point. The first frequency value and the first duration are both known values, and the specific values can be set according to the structure of the photovoltaic air conditioner and the oil return requirement. The method of performing photovoltaic multi-power peak scanning to obtain the maximum power value of the photovoltaic maximum power point can be realized by using the existing technology.

[0051] S13: When the maximum power value is less than the oil return power value, execute the oil return operation process.

[0052] The oil return power value is a known value, which is usually set when the air conditioner is manufactured. After obtaining the maximum power value of the photovoltaic maximum power point in step S12, compare it with the oil return power value. If the maximum power value is less than the oil return power value, execute the oil return operation process. The oil return operation process is a known process, which is to control the compressor to operate at the oil return frequency, so that the compressor can be lubricated by oil return.

[0053] If the maximum power value of the photovoltaic is less than the oil return power value, it indicates that the power value provided by the photovoltaic module is low. In order to avoid the output power provided by the photovoltaic being insufficient due to the reasons such as the power provided by the photovoltaic continuously reducing or the photovoltaic being unable to continuously output at the maximum power value, and thus making it difficult for the subsequent oil return, the air conditioner is forced to perform the oil return control process, so as to improve the reliability of the oil return control of the air conditioner, and thus improve the operation stability of the photovoltaic air conditioner. Moreover, the photovoltaic multi-power peak value scanning is performed under the condition that the compressor continuously operates at a low frequency, so as to effectively avoid the complexity of the multi-power peak value scanning under any working condition and the instability of the air conditioner operation caused by inaccurate scanning.

[0054] In some embodiments, the oil return operation frequency adopted in the oil return operation process is a set value, which is a fixed value. When the oil return operation is performed, the compressor is controlled to continuously operate at the oil return operation frequency.

[0055] In some other embodiments, during the oil return operation process, the oil return operation frequency is determined according to the maximum power value of the photovoltaic, and the compressor is controlled to continuously operate at the determined oil return operation frequency for a second duration. The second duration is a set time value. By determining the oil return operation frequency according to the maximum power value of the photovoltaic, the oil return operation frequency can be a variable value, and is a frequency value that is adapted to the maximum power value of the photovoltaic, so as to achieve the maximum oil return by fully utilizing the maximum power value of the photovoltaic, and improve the oil return effect. The specific method of determining the oil return operation frequency according to the maximum power value of the photovoltaic is not limited in this embodiment.

[0056] FIG. 2 shows a flowchart of another embodiment of the oil return control method of the photovoltaic air conditioner according to the present application. Specifically, it is a flowchart of an embodiment of the oil return control method when the maximum power value of the maximum power point of the photovoltaic obtained by the photovoltaic multi-power peak value scanning is not less than the oil return power value. If the maximum power value of the photovoltaic is less than the oil return power value, the method of the embodiment of FIG. 1 is adopted to perform the oil return control.

[0057] As shown in FIG. 2, the photovoltaic air conditioner of this embodiment adopts the following method to perform the oil return control.

[0058] S21: When the maximum power value is not less than the oil return power value, the real-time target operation power of the photovoltaic air conditioner is obtained.

[0059] When the operation frequency of the compressor is less than the first frequency value for a duration reaching the first duration, and the maximum power value of the maximum power point obtained by the scanning is not less than the oil return power value, the real-time target operation power of the photovoltaic air conditioner is obtained. The real-time target operation power is the operation power required by the photovoltaic air conditioner obtained in real time according to the set sampling frequency, and the obtaining method is realized by using the prior art, which is not specifically described and limited herein.

[0060] S22: When the maximum power value is less than the real-time target operation power, the first control mode is performed.

[0061] The real-time target operating power obtained in step S21 is compared with the maximum power value of the maximum power point of the photovoltaic module obtained through scanning. If the maximum power value is less than the real-time target operating power, it indicates that the output power provided by the photovoltaic module cannot meet the actual power requirement of the photovoltaic air conditioner, and the photovoltaic air conditioner cannot operate according to the real-time target operating power. At the same time, the oil return control also needs to be taken in a specific way to ensure the reliability of oil return. In this state, the following first control mode is executed on the photovoltaic air conditioner.

[0062] S23: Obtain the current real-time frequency of the compressor, reduce the current real-time frequency, and obtain the current actual operating frequency.

[0063] The current real-time frequency of the compressor is the target frequency of the compressor determined in the conventional manner of the photovoltaic air conditioner. In some embodiments, reducing the current real-time frequency to obtain the current actual operating frequency is to determine the frequency obtained by reducing the current real-time frequency by a set frequency value as the current actual operating frequency. The set frequency value can be a fixed frequency value or a variable frequency value. Since the power provided by the photovoltaic module cannot meet the power requirement of the air conditioner, the actual operating frequency of the compressor is reduced to match the output power of the photovoltaic module to ensure that the air conditioner can operate stably without stopping.

[0064] S24: Determine the current intermittent operation mode corresponding to the current actual operating frequency according to the correspondence between the actual operating frequency and the intermittent operation mode.

[0065] The correspondence between the actual operating frequency and the intermittent operation mode is preset, and the intermittent operation mode at least includes a continuous operation time and a shutdown time. The continuous operation time is the time during which the photovoltaic air conditioner continuously operates after entering the intermittent operation mode. It should be understood that after the continuous operation time of the photovoltaic air conditioner reaches the continuous operation time, the photovoltaic air conditioner will stop. The shutdown time is the shutdown duration of the photovoltaic air conditioner after the continuous operation time reaches the continuous operation time. It should be understood that after the continuous operation time of the photovoltaic air conditioner reaches the continuous operation time, the photovoltaic air conditioner will start operating again.

[0066] The preset correspondence between the actual operating frequency and the intermittent operation mode at least includes that different actual operating frequency values have a corresponding intermittent operation mode, corresponding to a continuous operation time and a shutdown time. After the current actual operating frequency is obtained in S23, the corresponding intermittent operation mode of the current actual operating frequency can be obtained according to the preset correspondence between the frequency and the intermittent operation mode, and determined as the current intermittent operation mode. The continuous operation time and the shutdown time in the current intermittent operation mode are determined as the current continuous operation time and the current shutdown time, respectively.

[0067] S25: when the current actual running frequency is less than the second frequency value and the interval time from the last oil return reaches the interval time threshold, an oil return operation process is performed.

[0068] The second frequency value is a preset value, and if the actual running frequency of the compressor is less than the second frequency value, the problem of poor oil return of the compressor is prone to occur. In some embodiments, the second frequency value is an oil return frequency threshold of the compressor, and the value is less than the first frequency value.

[0069] The interval time from the last oil return can be obtained by setting a timing time to accumulate the timing.

[0070] The interval time threshold is a dynamically variable value, which is determined according to the continuous running time in the m consecutive intermittent operation modes. Moreover, the interval time threshold and the continuous running time in the m consecutive intermittent operation modes are in a positive correlation relationship. The purpose of determining the interval time threshold in this way is that the longer the continuous running time in the intermittent operation mode, the higher the actual running frequency of the compressor is generally, and the lower the probability of poor oil return of the compressor is generally. Therefore, the forced oil return interval time can be increased, and the influence of forced oil return on the normal operation of the photovoltaic air conditioner can be reduced.

[0071] In other embodiments, the interval time threshold is determined according to the continuous running time in the m consecutive intermittent operation modes, and specifically includes:

[0072] The continuous running time in each intermittent operation mode in the m consecutive intermittent operation modes is obtained, the m continuous running times are summed, and the sum is determined as the interval time threshold. By using this method to determine the interval time threshold, the interval time threshold and the continuous running time in the m consecutive intermittent operation modes are in a positive correlation relationship, and the interval time threshold can be obtained conveniently and quickly.

[0073] When the current actual running frequency determined in step S24 is less than the second frequency value and the interval time from the last oil return reaches the interval time threshold, the oil return operation process is performed. The specific execution process of the oil return operation process is described in the foregoing embodiments.

[0074] In the above embodiment, when the maximum power value that can be provided by the photovoltaic module is not less than the oil return power value of the photovoltaic air conditioner, but is less than the real-time target operating power of the photovoltaic air conditioner, the first control mode of compressor frequency reduction operation is executed to ensure that the photovoltaic air conditioner can be successfully started for oil return in the intermittent operation mode with insufficient power provided by the photovoltaic module and insufficient continuous operation time, and to ensure the oil return effect of the photovoltaic air conditioner and avoid instability of the air conditioner caused by failure to return oil. In the first control mode, the intermittent operation mode is determined according to the actual operating frequency after frequency reduction, the interval threshold is determined according to the continuous operation time in the intermittent operation mode, and the interval threshold is used as a parameter for determining whether to execute the oil return operation process. When the actual operating frequency after frequency reduction is less than the second frequency value and the interval time from the previous oil return reaches the interval threshold, the oil return process is executed. Thus, by using the continuous operation time in the intermittent operation mode to determine the interval threshold and using the interval time from the previous oil return reaching the interval threshold as a time reference for determining whether to execute the oil return control, it can be ensured that the photovoltaic air conditioner can be successfully started for oil return in the intermittent operation mode with insufficient continuous operation time after frequency reduction, and the oil return effect of the photovoltaic air conditioner can be ensured. Moreover, the interval threshold is dynamically adjusted according to the actual operation duration corresponding to the actual operating frequency of the photovoltaic air conditioner, thereby improving the rationality and reliability of the oil return control.

[0075] In other embodiments, if the current actual operating frequency is not less than the second frequency value and / or the interval time from the previous oil return does not reach the interval threshold, the forced oil return control is not required, and the photovoltaic air conditioner can be directly controlled to operate according to the current actual operating frequency and the current intermittent operation mode. Specifically, the photovoltaic air conditioner is controlled to operate at the current actual operating frequency with a continuous operation time of the current continuous operation time, then the photovoltaic air conditioner is controlled to stop operating with a stop time of the current stop time, and the photovoltaic air conditioner is controlled to start operating again after the stop time reaches the current stop time.

[0076] In other embodiments, the first control mode further includes: obtaining the current frequency reduction operation times; and executing the process of obtaining the current real-time frequency of the compressor of the photovoltaic air conditioner, reducing the current real-time frequency, and obtaining the current actual operating frequency in S23 when the current frequency reduction operation times are less than a preset number threshold.

[0077] In the above embodiment, the frequency reduction operation times are used as a preset parameter, and the value thereof reflects the number of times that the photovoltaic air conditioner is operated at a reduced frequency due to the maximum power value output by the photovoltaic module being less than the real-time target operating power of the air conditioner within a certain time. The initial value thereof is 0, and the value thereof is increased by 1 each time the condition that the maximum power value output by the photovoltaic module is less than the real-time target operating power of the air conditioner is met. When the condition that the maximum power value output by the photovoltaic module is less than the real-time target operating power of the air conditioner is not met, the number of times is reset to 0.

[0078] The current frequency reduction operation times is the value of the frequency reduction operation times obtained in real time when entering the first control mode. After obtaining the current frequency reduction operation times, it is compared with the known preset times threshold. The preset times threshold is a known value.

[0079] If the current frequency reduction operation times is less than the preset times threshold, the current real-time frequency of the compressor of the photovoltaic air conditioner is obtained, the current real-time frequency is reduced to obtain the current actual operation frequency, and the subsequent processing process such as the intermittent operation mode is determined according to the current actual operation frequency.

[0080] In some other embodiments, if the current frequency reduction operation times is greater than the preset times threshold, it indicates that the photovoltaic air conditioner has been frequency-reduced for many times because the maximum output power of the photovoltaic module is less than the target operation power of the air conditioner. This state indicates that the current illumination condition is poor, and the photovoltaic module cannot provide sufficient output power in a short time. In order to protect the photovoltaic air conditioner and avoid long-time low-frequency operation of the compressor, the photovoltaic air conditioner is controlled to be shut down.

[0081] In some other embodiments, the continuous operation time and the shutdown time in the intermittent operation mode are both variable values.

[0082] For the variable continuous operation time in the intermittent operation mode, the following formula is used to determine: T=k1xf+k2xn. Wherein, T is the continuous operation time, f is the current actual operation frequency, n is the current frequency reduction operation times, k1 is a known coefficient greater than 0, and k2 is a known coefficient less than 0. That is, the continuous operation time is determined by the current actual operation frequency and the current frequency reduction operation times, and the continuous operation time is positively correlated with the current actual operation frequency and negatively correlated with the current frequency reduction operation times. Controlling the photovoltaic air conditioner based on the continuous operation time determined in this way can further improve the balanced performance between the reliability of the photovoltaic air conditioner operation and the comfort of using the photovoltaic air conditioner.

[0083] For the variable shutdown time in the intermittent operation mode, the following formula is used to determine: t=k3xn. Wherein, t is the shutdown time, n is the current frequency reduction operation times, and k3 is a known coefficient greater than 0. That is, the shutdown time is determined according to the current frequency reduction operation times, and the two are positively correlated. Determining the shutdown time in this way can adaptively adjust the shutdown time according to the output power state of the photovoltaic module, reduce the low-frequency operation time of the compressor as much as possible, and further improve the reliability of the photovoltaic air conditioner operation.

[0084] In some other embodiments, in the first control mode, it is also determined whether the oil return operation process is successful. In some embodiments, if the compressor continues to operate at the oil return operation frequency for a set duration, for example, reaches a second duration, it is determined that the oil return is successful. Otherwise, it is determined that the oil return is unsuccessful. If it is determined that the oil return is successful, the interval time is cleared and the timing is restarted. It should be understood that the interval time timing process is only valid in the first control mode. That is, the interval time is only timed in the first control mode. If it is determined that the oil return is unsuccessful, the interval time continues to accumulate the timing.

[0085] In some other embodiments, when the maximum power value corresponding to the maximum power point of the scanned photovoltaic module is not less than the oil return power value, and is also not less than the real-time target operating power, the photovoltaic module can provide sufficient electrical energy to the photovoltaic air conditioner, and the photovoltaic air conditioner does not need to operate at a reduced frequency due to insufficient power supply from the photovoltaic module. In this working condition, the second control mode is executed to control the compressor to return oil in a conventional manner, avoiding forced oil return to affect the normal operation of the photovoltaic air conditioner. The second control mode includes: obtaining the current real-time frequency of the compressor of the photovoltaic air conditioner, and executing the oil return operation process when the duration of the current real-time frequency being less than the second frequency value reaches a third duration. The third duration is a known value.

[0086] In some other embodiments, in order to improve the scanning speed and scanning accuracy, photovoltaic multi-power peak scanning is performed to obtain the photovoltaic maximum power point, which specifically includes:

[0087] On the photovoltaic power-voltage curve, the working point with the voltage being the open circuit voltage is taken as the initial search point, and the search is performed in the direction of decreasing voltage. The first peak power point is searched, and the first voltage and the first power corresponding to the first peak power point are recorded. The search method is realized by using the existing technology, for example, by using the perturbation and observation method.

[0088] The difference voltage is determined according to the first voltage, and the difference voltage is less than the first voltage. The specific determination method is pre-set.

[0089] The working point with the voltage equal to the difference voltage is taken as the new search starting point to continue the search. The subsequent searched peak power point is recorded as the most recent peak power point, and the voltage and power corresponding to the most recent peak power point are recorded.

[0090] The sum of the voltage corresponding to the most recent peak power point and the difference voltage is taken as the voltage of the next search starting point;

[0091] Before continuing the search, it is first determined whether the difference between the first voltage and the voltage of the next search starting point is less than the difference voltage. If not, the working point with the voltage equal to the voltage of the next search starting point is taken as the new search starting point to continue the search. Until the difference between the first voltage and the voltage of the next search starting point is less than the difference voltage, the search is stopped.

[0092] It should be understood that if the difference between the first voltage and the voltage of the next search starting point is not less than the difference voltage, and the search is continued at the working point with the voltage equal to the voltage of the next search starting point, after the peak power point is searched, the voltage and power corresponding to the peak power point are recorded as the latest peak power point. Then, the sum of the voltage corresponding to the peak power point and the difference voltage is taken as the voltage of the next search starting point, and the voltage judgment process is performed again.

[0093] After the search is stopped, the point with the maximum power among all the searched peak power points is determined as the photovoltaic maximum power point.

[0094] In the above multi-power peak scanning process, since the search is continued at the working point with the voltage equal to the difference voltage, the size of the difference voltage plays a role in limiting the search range. Moreover, the sum of the voltage corresponding to the latest peak power point and the difference voltage is taken as the voltage of the next search starting point, so the size of the difference voltage also plays a role in determining the distance of the next search starting point from the latest peak power point. Before the search is continued, it is also judged whether the difference between the first voltage and the voltage of the next search starting point is less than the difference voltage, so the size of the difference voltage also plays a role in determining whether the search is ended. It can be seen that the size of the difference voltage plays a very important role in the multi-power peak scanning process, and is related to the speed and accuracy of the search.

[0095] In some embodiments, the method for determining the difference voltage according to the first voltage can be determined according to experiments or experience.

[0096] In some other embodiments, the difference voltage is determined according to the first voltage, specifically including:

[0097] The number N of the series-connected cell panels of the photovoltaic array is obtained, and the difference voltage is determined according to the first voltage and the number N, and the difference voltage is positively related to the first voltage and negatively related to the number N. The more the number of the series-connected cell panels of the photovoltaic array, the greater the power output by the photovoltaic array, the greater the influence of the environment, and the more the peak power points. The difference voltage is set to be negatively related to the number N of the cell panels, the greater the number N, the smaller the difference voltage, which can increase the search range and the search frequency, and further improve the search speed and the search accuracy of the maximum power point.

[0098] Some other embodiments of the present application also provide a photovoltaic air conditioner, which comprises an air conditioner body and a photovoltaic module, and the air conditioner body comprises a compressor. The photovoltaic air conditioner further comprises a controller configured to perform the photovoltaic air conditioner oil return control according to the processes of the embodiments of the photovoltaic air conditioner oil return control method shown in FIG. 1 or FIG. 2 and other embodiments, so as to achieve the technical effects corresponding to the method embodiments.

[0099] Other embodiments of the present application also provide a computer storage medium, which stores a computer program. When the computer program is executed by a processor, the photovoltaic air conditioner oil return control method of the embodiments of FIG. 1, FIG. 2 and other embodiments is implemented, and the technical effects of the corresponding embodiments are achieved.

[0100] The computer storage medium described above can be implemented by any type of volatile or nonvolatile storage devices or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk or optical disk. The computer storage medium can be any available storage medium that can be accessed by a general-purpose or special-purpose computer.

[0101] In some embodiments, the computer storage medium is coupled to the processor, so that the processor can read information from the storage medium and write information to the storage medium. Of course, the storage medium can also be an integral part of the processor. The processor and the storage medium can be located in an application specific integrated circuit (ASIC). Of course, the processor and the storage medium can also exist as discrete components in the device.

[0102] The above embodiments are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing embodiments, the technical solutions recorded in the foregoing embodiments can still be modified by those of ordinary skill in the art, or some technical features can be replaced by equivalent ones; and these modifications or replacements do not make the corresponding technical solutions deviate from the spirit and scope of the technical solutions claimed by the present application.

Claims

1. A photovoltaic air conditioning oil return control method, characterized in that, The method includes: Obtain the operating frequency of the compressor in the photovoltaic air conditioner; When the duration of the operating frequency being less than the first frequency value reaches the first duration, a photovoltaic multi-power peak scan is performed to obtain the maximum power value of the photovoltaic maximum power point. When the maximum power value is less than the return oil power value, the return oil operation process is executed.

2. The photovoltaic air conditioning oil return control method according to claim 1, characterized in that, During the oil return operation, the oil return operation frequency is determined based on the maximum power value of the photovoltaic system, and the compressor is controlled to run continuously at the oil return operation frequency for a second duration.

3. The photovoltaic air conditioning oil return control method according to claim 1, characterized in that, The method further includes: When the maximum power value is not less than the oil return power value, the real-time target operating power of the photovoltaic air conditioner is obtained; When the maximum power value is less than the real-time target operating power, the following first control mode is executed: Obtain the current real-time frequency of the compressor of the photovoltaic air conditioner, reduce the current real-time frequency, and obtain the current actual operating frequency; Based on the correspondence between the actual operating frequency and the intermittent operating mode, the current intermittent operating mode corresponding to the current actual operating frequency is determined; the intermittent operating mode includes at least continuous operating time and downtime. When the current actual operating frequency is less than the second frequency value and the interval between the previous oil return reaches the interval time threshold, the oil return operation process is executed; the interval time threshold is determined based on the continuous operating time in m consecutive intermittent operation modes.

4. The photovoltaic air conditioning oil return control method according to claim 3, characterized in that, The first control mode also includes: Determine whether the oil return process is successful; If so, reset the interval time to zero and restart the timer; If not, the interval time continues to accumulate.

5. The photovoltaic air conditioning oil return control method according to claim 3, characterized in that, The first control mode also includes: If the current actual operating frequency is not less than the second frequency value, and / or the interval time from the previous oil return has not reached the interval time threshold, the photovoltaic air conditioner is controlled to operate according to the current actual operating frequency and the current intermittent operating mode.

6. The photovoltaic air conditioning oil return control method according to claim 3, characterized in that, The method further includes: When the maximum power value is not less than the return oil power value, and the maximum power value is not less than the current real-time operating power, the following second control mode is executed: The current real-time frequency of the compressor of the photovoltaic air conditioner is obtained, and when the duration during which the current real-time frequency is less than the second frequency value reaches a third duration, the oil return operation process is executed.

7. The photovoltaic air conditioning oil return control method according to any one of claims 1 to 6, characterized in that, The photovoltaic multi-power peak scan is performed to obtain the photovoltaic maximum power point, specifically including: On the photovoltaic power-voltage curve, the operating point with the open-circuit voltage is taken as the initial search point. The search proceeds in the direction of decreasing voltage until the first peak power point is found. The first voltage and the first power corresponding to the first peak power point are recorded. The difference voltage is determined based on the first voltage; the difference voltage is less than the first voltage. The operating point where the voltage equals the voltage difference is used as the new search starting point to continue the search. The peak power point found in the subsequent search is recorded as the most recent peak power point, and the voltage and power corresponding to the most recent peak power point are recorded. The sum of the voltage corresponding to the most recent peak power point and the difference voltage is used as the voltage of the next search starting point; Determine whether the difference between the first voltage and the voltage of the next search starting point is less than the difference voltage; if not, take the operating point with a voltage equal to the voltage of the next search starting point as the new search starting point and continue searching; until the difference between the first voltage and the voltage of the next search starting point is less than the difference voltage, then stop searching; After stopping the search, the point with the highest power among all the peak power points found is determined as the photovoltaic maximum power point.

8. The photovoltaic air conditioning oil return control method according to claim 7, characterized in that, Determining the difference voltage based on the first voltage specifically includes: The number N of the photovoltaic array connected in series is obtained, and the difference voltage is determined based on the first voltage and the number N. The difference voltage is positively correlated with the first voltage and negatively correlated with the number N.

9. A photovoltaic air conditioner, comprising an air conditioner body and a photovoltaic module, wherein the air conditioner body includes a compressor, characterized in that, The photovoltaic air conditioner also includes a controller, which is configured to execute the photovoltaic air conditioner oil return control method according to any one of claims 1 to 8.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the photovoltaic air conditioning oil return control method according to any one of claims 1 to 8.

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