Photovoltaic air conditioner and oil return control method thereof

Abstract

The application discloses a photovoltaic air conditioner and an oil return control method thereof. The oil return control method comprises the following steps: acquiring an operating frequency of a compressor of the photovoltaic air conditioner when the compressor is working; when a 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 application can improve the reliability of oil return control of the photovoltaic air conditioner.

Description

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. Summary of the Invention

[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.

[0005] To achieve the above-mentioned objectives, the present invention employs the following technical solution: A photovoltaic air conditioner oil return control method, comprising: 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.

[0006] In some embodiments of this application, during the oil return operation, the oil return operation frequency is determined based on the maximum photovoltaic power value, and the compressor is controlled to continuously operate at the oil return operation frequency for a second duration.

[0007] In some embodiments of this application, 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.

[0008] In some embodiments of this application, the first control mode further 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.

[0009] In some embodiments of this application, the first control mode further 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.

[0010] In some embodiments of this application, 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.

[0011] In some embodiments of this application, performing the photovoltaic multi-power peak scan to obtain the photovoltaic maximum power point specifically includes: 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.

[0012] In some embodiments of this application, 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.

[0013] Another object of the present invention is to provide a photovoltaic air conditioner, including an air conditioner body and a photovoltaic module, wherein the air conditioner body includes a compressor, and the photovoltaic air conditioner also includes a controller configured to execute the above-described photovoltaic air conditioner oil return control method.

[0014] Another object of the present invention is to provide a computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, the above-described photovoltaic air conditioner oil return control method is implemented.

[0015] Compared with the prior art, the advantages and positive effects of the present invention are: The photovoltaic air conditioner and its oil return control method provided by this invention perform a photovoltaic multi-power peak scan when the compressor's operating frequency is lower than a set first frequency value for a duration that reaches a first duration. This scan obtains the maximum power value of the photovoltaic maximum power point. The maximum power value is then compared with the oil return power value. If the maximum power value is less than the oil return power value, oil return operation control is implemented. By employing this control method, multi-power peak scanning is performed only when the compressor is continuously operating at low frequency, effectively avoiding the complexity of performing multi-power peak scanning under all operating conditions and the instability caused by inaccurate scanning. When the maximum power value obtained from the scan is less than the oil return power value, it indicates that the photovoltaic module's output power is low, thus forcibly executing oil return control. This prevents subsequent difficulties in normal oil return due to insufficient output power provided by the photovoltaic module, improving the reliability of the air conditioner's oil return control and thereby enhancing the operational stability of the photovoltaic air conditioner.

[0016] Other features and advantages of the present invention will become clearer after reading the detailed embodiments of the invention in conjunction with the accompanying drawings. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart of one embodiment of the photovoltaic air conditioning oil return control method of the present invention; Figure 2 This is a flowchart of another embodiment of the photovoltaic air conditioning oil return control method of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0020] It should be noted that the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they can be implemented by those skilled in the art. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0021] Figure 1 The diagram shows a flowchart of one embodiment of the photovoltaic air conditioner oil return control method of the present invention. 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 electrical energy for the operation of the air conditioner body.

[0022] like Figure 1 As shown, the photovoltaic air conditioner in this embodiment uses the following method for oil return control.

[0023] S11: Obtain the operating frequency of the compressor when the photovoltaic air conditioner is working.

[0024] 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.

[0025] While obtaining the operating frequency of the compressor, the operating time of each operating frequency must also be accumulated and recorded. When obtaining the operating frequency in step S11, the duration of the compressor operating at that operating frequency can also be obtained simultaneously.

[0026] The operating frequency obtained in step S11 is compared with a first frequency value, and the duration of this operating frequency is compared with a first duration. If 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 corresponding to the photovoltaic maximum power point. Both the first frequency value and the first duration are preset known values, and their specific values ​​can be set according to the photovoltaic air conditioning structure and oil return requirements. The method for obtaining the maximum power value of the photovoltaic maximum power point by performing a photovoltaic multi-power peak scan can be implemented using existing technologies.

[0027] S13: When the maximum power value is less than the return oil power value, execute the return oil operation process.

[0028] The oil return power value is a known value, usually set at the factory when the air conditioner leaves the factory. After obtaining the maximum power value of the photovoltaic maximum power point in step S12, it is compared with the oil return power value. If the maximum power value is less than the oil return power value, the oil return operation process will be executed. The oil return operation process is a known process, specifically controlling the compressor to operate at the oil return frequency, with the aim of allowing the compressor to be lubricated using the returned oil.

[0029] If the maximum power value of the photovoltaic module is less than the oil return power value, it indicates that the power provided by the photovoltaic module is low. To prevent insufficient output power from the photovoltaic module due to reasons such as a further decrease in the power provided or the inability to continuously output at the maximum power value, which would make it difficult for the oil to return normally, the air conditioner will be forced to execute the oil return control process. This improves the reliability of the air conditioner's oil return control and thus improves the operational stability of the photovoltaic air conditioner. Furthermore, the photovoltaic multi-power peak scanning is performed only when the compressor is running at a continuous low frequency, effectively avoiding the complexity of performing multi-power peak scanning under all operating conditions and the instability of air conditioner operation caused by inaccurate scanning.

[0030] In some embodiments, the oil return operating frequency used during the oil return operation is a set value, which is a fixed value. During oil return operation, the compressor is controlled to run continuously at the oil return operating frequency.

[0031] In other embodiments, during the oil return operation, the oil return operating frequency is determined based on the maximum photovoltaic power value, and the compressor is controlled to continuously operate at the determined oil return operating frequency for a second duration. The second duration is a set time value. By determining the oil return operating frequency based on the maximum photovoltaic power value, the oil return operating frequency can be made a variable value that is adapted to the maximum photovoltaic power value, thereby fully utilizing the maximum photovoltaic power value to obtain as much oil return as possible and improving the oil return effect. This embodiment does not limit the specific method for determining the oil return operating frequency based on the maximum photovoltaic power value.

[0032] Figure 2 The diagram shows a flowchart of another embodiment of the photovoltaic air conditioning oil return control method of the present invention. Specifically, it is a flowchart of an embodiment of the oil return control method when the maximum power value of the photovoltaic maximum power point obtained through photovoltaic multi-power peak scanning is not less than the oil return power value. If the photovoltaic maximum power value is less than the oil return power value, a method will be adopted. Figure 1 The method in this embodiment performs oil return control.

[0033] like Figure 2 As shown, the photovoltaic air conditioner in this embodiment uses the following method for oil return control.

[0034] S21: Obtain the real-time target operating power of the photovoltaic air conditioner when the maximum power value is not less than the return oil power value.

[0035] When the compressor operating frequency is less than a first frequency value for a duration that reaches the first duration, and the maximum power value of the photovoltaic maximum power point obtained by scanning is not less than the oil return power value, the real-time target operating power of the photovoltaic air conditioner is acquired. The real-time target operating power is the operating power required by the photovoltaic air conditioner, which is acquired in real time according to the set sampling frequency. The acquisition method adopts existing technology and will not be specifically described or limited here.

[0036] S22: When the maximum power value is less than the real-time target operating power, execute the first control mode.

[0037] The real-time target operating power obtained in step S21 is compared with the maximum power value of the photovoltaic maximum power point 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 demand of the photovoltaic air conditioner. In this case, the photovoltaic air conditioner cannot operate according to the real-time target operating power. At the same time, its oil return control also needs to be carried out in a specific way to ensure the reliability of oil return. In this state, the photovoltaic air conditioner will be executed in the following first control mode.

[0038] S23: Obtain the current real-time frequency of the compressor, reduce the current real-time frequency, and obtain the current actual operating frequency.

[0039] The compressor's current real-time frequency is the target frequency determined according to the conventional method for photovoltaic air conditioning. In some embodiments, reducing this current real-time frequency to obtain the current actual operating frequency involves subtracting a set frequency value from the current real-time frequency and determining this 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 system cannot meet the power requirements of the air conditioner, the compressor's actual operating frequency is reduced to match the photovoltaic power output in order to ensure stable operation without stopping the air conditioner.

[0040] S24: Based on the correspondence between the actual operating frequency and the intermittent operating mode, determine the current intermittent operating mode corresponding to the current actual operating frequency.

[0041] The system has a pre-defined correspondence between actual operating frequencies and intermittent operating modes, where each intermittent operating mode includes at least continuous operating time and shutdown time. The continuous operating time is the duration the photovoltaic air conditioner operates continuously after entering this intermittent operating mode. It should be understood that the photovoltaic air conditioner will shut down after the continuous operating time has elapsed. The shutdown time is the duration of shutdown after the continuous operating time has elapsed after entering this intermittent operating mode. It should be understood that the photovoltaic air conditioner will restart operation after the shutdown duration has elapsed.

[0042] The preset correspondence between actual operating frequencies and intermittent operating modes includes at least one corresponding intermittent operating mode for different actual operating frequency values, corresponding to one continuous operating time and one downtime. After obtaining the current actual operating frequency in S23, the intermittent operating mode corresponding to the current actual operating frequency can be obtained according to the preset correspondence between frequency and intermittent operating mode, and determined as the current intermittent operating mode. Then, the continuous operating time and downtime in the current intermittent operating mode are respectively determined as the current continuous operating time and the current downtime.

[0043] S25: 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, execute the oil return operation process.

[0044] The second frequency value is a preset value. If the actual operating frequency of the compressor is less than this second frequency value, poor oil return in the compressor is likely to occur. In some embodiments, the second frequency value is the compressor's oil return frequency threshold, and this value is less than the first frequency value.

[0045] The interval between the last oil return and the last return can be obtained by setting a timer and accumulating the time.

[0046] The interval time threshold is a dynamically variable value, specifically determined based on the continuous operating time in m consecutive intermittent operation modes. Furthermore, the interval time threshold is positively correlated with the continuous operating time in the m consecutive intermittent operation modes. The purpose of determining the interval time threshold in this way is that the longer the continuous operating time in the intermittent operation mode, the higher the actual operating frequency of the compressor generally is, and the lower the probability of compressor oil return failure generally is. Therefore, the forced oil return interval time can be increased, reducing the impact of forced oil return on the normal operation of the photovoltaic air conditioner.

[0047] In other embodiments, the interval time threshold is determined based on the duration of continuous operation in m consecutive intermittent operation modes, specifically including: The method involves obtaining the duration of each intermittent operation mode in m consecutive intermittent operation modes, summing the m durations, and using the sum as the interval time threshold. This method ensures a positive correlation between the interval time threshold and the duration of each of the m consecutive intermittent operation modes, and also provides a convenient and quick way to obtain the interval time threshold.

[0048] When the current actual operating frequency determined in step S24 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 will be executed. For the specific execution process of the oil return operation, please refer to the description in the foregoing embodiments.

[0049] In the above embodiments, when the maximum power value that the photovoltaic module can provide is not less than the oil return power value of the photovoltaic air conditioner, but less than the real-time target operating power of the photovoltaic air conditioner, the first control mode of compressor frequency reduction operation is executed. This ensures that the oil return can still be successfully started in the intermittent working mode where the power value provided by the photovoltaic module is insufficient, forcing the air conditioner to operate at a reduced frequency and the continuous operating time is insufficient. This ensures the oil return effect of the photovoltaic air conditioner and avoids instability caused by the inability to operate with oil return. Moreover, in the first control mode, the intermittent operating mode is determined based on the actual operating frequency after frequency reduction, and the interval time threshold is determined based on the continuous operating time in the intermittent operating mode as a parameter for whether to execute the oil return process. When the actual operating frequency after frequency reduction is less than the second frequency value and the interval time since the last oil return reaches the interval time threshold, the oil return process is executed. Thus, by using the continuous operating time in the intermittent operating mode to determine the interval time threshold and using the interval time since the last oil return reaching the interval time threshold as a time reference for whether to execute the oil return control, it can be ensured that the photovoltaic air conditioner can still smoothly enter the oil return process in the intermittent working mode with frequency reduction and insufficient continuous operating time, ensuring the oil return effect of the photovoltaic air conditioner. Moreover, the interval time threshold is dynamically adjusted according to the actual operating duration corresponding to the actual operating frequency of the photovoltaic air conditioner, which improves the rationality and reliability of the oil return control.

[0050] In some other embodiments, if the current actual operating frequency is not less than the second frequency value, and / or the interval between the last oil return and the previous oil return has not reached the interval threshold, then there is no need for forced oil return control; the photovoltaic air conditioner can be controlled directly based on the current actual operating frequency and the current intermittent operating mode. Specifically, the photovoltaic air conditioner is controlled to operate at the current actual operating frequency, with the continuous operating time being the current continuous operating time; then the photovoltaic air conditioner is controlled to stop, with the stop time being the current stop time; after the stop time reaches the current stop time, the photovoltaic air conditioner is controlled to restart.

[0051] In some other embodiments, the first control mode further includes: obtaining the current number of frequency reduction operations; when the current number of frequency reduction operations is less than a preset threshold, executing the process in S23 of obtaining the current real-time frequency of the photovoltaic air conditioner's compressor, reducing the current real-time frequency, and obtaining the current actual operating frequency.

[0052] The frequency reduction operation count is a preset parameter, which reflects the number of times the photovoltaic air conditioner reduces its frequency within a certain period of time because the maximum power output of the photovoltaic module is less than the real-time target operating power of the air conditioner. Its initial value is 0. As long as the maximum power output of the photovoltaic module is continuously less than the real-time target operating power of the air conditioner, its value will increase by 1 each time the condition is met; if the condition of reducing the frequency due to the maximum power output of the photovoltaic module being less than the real-time target operating power of the air conditioner is not met, its count will be reset to zero.

[0053] The current frequency reduction operation count is the value of the frequency reduction operation count acquired in real time when entering the first control mode. After acquiring the current frequency reduction operation count, it is compared with a known preset count threshold. The preset count threshold is a known value.

[0054] If the current frequency reduction operation count is less than the preset threshold, the current real-time frequency of the photovoltaic air conditioner compressor will be obtained, the current real-time frequency will be reduced, the current actual operating frequency will be obtained, and subsequent processing procedures such as determining the intermittent operation mode will be performed based on the current actual operating frequency.

[0055] In some other embodiments, if the number of times the frequency is reduced exceeds a preset threshold, it indicates that the photovoltaic air conditioner has repeatedly reduced its frequency because the maximum power output by the photovoltaic module is less than the target operating power of the air conditioner. This state indicates that the current lighting conditions are poor, and the photovoltaic module cannot provide sufficient output power in a short period of time. To protect the photovoltaic air conditioner and prevent the compressor from running at low frequency for a long time, the photovoltaic air conditioner will be shut down.

[0056] In some other embodiments, the continuous running time and downtime in the intermittent operation mode are both variable values.

[0057] For the variable continuous operating time in intermittent operation mode, the following formula is used to determine it: T = k1 × f + k2 × n. Where T is the continuous operating time, f is the current actual operating frequency, n is the current number of frequency reduction operations, k1 is a known coefficient greater than 0, and k2 is a known coefficient less than 0. That is, the continuous operating time is jointly determined by the current actual operating frequency and the current number of frequency reduction operations, and the continuous operating time is positively correlated with the current actual operating frequency and negatively correlated with the current number of frequency reduction operations. Controlling the photovoltaic air conditioner based on this determined continuous operating time can further improve the balance between the reliability of photovoltaic air conditioner operation and the comfort of using it.

[0058] For the variable downtime in intermittent operation mode, the following formula is used to determine it: t = k3 × n. Where t is the downtime, n is the current number of frequency reduction operations, and k3 is a known coefficient greater than 0. That is, the downtime is determined based on the current number of frequency reduction operations, and the two are positively correlated. Determining the downtime in this way allows for adaptive adjustment based on the output power status of the photovoltaic modules, minimizing the low-frequency operation time of the compressor and further improving the reliability of the photovoltaic air conditioner.

[0059] In some other embodiments, in the first control mode, it is also determined whether the oil return process is successful. In some embodiments, if the compressor operates continuously at the oil return frequency for a set duration, such as a second duration, the oil return is considered successful. Otherwise, the oil return is considered unsuccessful. If the oil return is determined to be successful, the interval time is reset to zero and the timing restarts. 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 the oil return is determined to be unsuccessful, the interval time continues to accumulate.

[0060] In some other embodiments, when the maximum power value corresponding to the maximum power point of the photovoltaic module obtained by scanning is not less than the oil return power value and 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 reduce its frequency due to insufficient power supply from the photovoltaic module. Under this condition, a second control mode will be executed to control the compressor to return oil in the conventional manner, avoiding forced oil return from affecting 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 current real-time frequency is less than a second frequency value for a duration reaching a third duration. The third duration is a known value.

[0061] In other embodiments, to improve scanning speed and accuracy, photovoltaic multi-power peak scanning is performed to obtain the photovoltaic maximum power point, specifically including: On the photovoltaic power-voltage curve, the operating point where the voltage is the open-circuit voltage is used 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 search method employs existing technologies, such as the perturbation-observation method.

[0062] The difference voltage is determined based on the first voltage, and the difference voltage is less than the first voltage. The specific determination method is preset.

[0063] The operating point where the voltage equals the voltage difference is used as the new starting point for 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.

[0064] The sum of the voltage corresponding to the most recent peak power point and the voltage difference is used as the voltage of the next search starting point; Before continuing the search, first 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 the search; until the difference between the first voltage and the voltage of the next search starting point is less than the difference voltage, then stop the search.

[0065] 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, the operating point whose voltage equals the voltage of the next search starting point is used as the new search starting point to continue the search. After finding the peak power point, it is taken as the most recent peak power point, and the voltage and power corresponding to the peak power point are recorded. Then, the sum of the voltage corresponding to the peak power point and the difference voltage is used as the voltage of the next search starting point, and the above voltage judgment process is repeated.

[0066] After the search stops, the point with the highest power among all the peak power points found is determined as the photovoltaic maximum power point.

[0067] In the aforementioned multi-power peak scanning process, since the operating point with voltage equal to the voltage difference is used as the new search starting point, the magnitude of the voltage difference limits the search range. Furthermore, the sum of the voltage corresponding to the most recent peak power point and the voltage difference is used as the voltage of the next search starting point; therefore, the magnitude of the voltage difference also determines the distance between the next search starting point and the most recent peak power point. Before continuing the search, it is necessary to determine whether the difference between the first voltage and the voltage of the next search starting point is less than the voltage difference; therefore, the magnitude of the voltage difference also determines whether to end the search. Thus, it is clear that the magnitude of the voltage difference plays a crucial role in the multi-power peak scanning process, affecting both the search speed and the search accuracy.

[0068] In some embodiments, a method for calculating the difference voltage based on the first voltage can be determined based on experiments or experience.

[0069] In some other embodiments, determining the difference voltage based on the first voltage specifically includes: The number N of solar panels connected in series in the photovoltaic array is obtained. A differential voltage is determined based on a first voltage and the number N, with the differential voltage positively correlated with the first voltage and negatively correlated with the number N. The more solar panels connected in series in the photovoltaic array, the greater the photovoltaic output power, but also the greater the susceptibility to environmental influences and the more peak power points. Setting the differential voltage to be negatively correlated with the number N of solar panels—a larger number N results in a smaller differential voltage—increases the search range and search frequency, thereby improving the search speed and accuracy of the maximum power point.

[0070] Other embodiments of the present invention also provide a photovoltaic air conditioner, which includes an air conditioner body and a photovoltaic module, the air conditioner body including a compressor. The photovoltaic air conditioner also includes a controller configured to... Figure 1 or Figure 2 The photovoltaic air conditioner oil return control method embodiment and other embodiments are used to control the photovoltaic air conditioner oil return, achieving the corresponding technical effects of each method embodiment.

[0071] Other embodiments of the present invention also provide a computer storage medium on which a computer program is stored, and when the computer program is executed by a processor, it implements... Figure 1 Implementation examples Figure 2 The embodiments and other embodiments of the photovoltaic air conditioning oil return control method, and achieve the technical effects of the corresponding embodiments.

[0072] The aforementioned computer storage media can be implemented using any type of volatile or non-volatile storage device 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 media can be any available storage medium accessible to general-purpose or special-purpose computers.

[0073] In some embodiments, a computer storage medium is coupled to a processor, enabling the processor to read information from and write information to the storage medium. Alternatively, the storage medium can be an integral part of the processor. Both the processor and the storage medium can reside in application-specific integrated circuits (ASICs). Of course, the processor and storage medium can also exist as discrete components in the device.

[0074] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions claimed by the present invention.

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; 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.

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 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.

4. The photovoltaic air conditioning oil return control method according to claim 1, 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.

5. 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 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.

6. The photovoltaic air conditioning oil return control method according to any one of claims 1 to 5, 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.

7. The photovoltaic air conditioning oil return control method according to claim 6, 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.

8. 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 7.

9. 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 7.

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