Photovoltaic air conditioner and its oil return control method and control device

Abstract

This invention discloses a photovoltaic air conditioner and its oil return control method and device, achieving the technical objective of improving the reliability of oil return control in photovoltaic air conditioners. The control method includes: acquiring the current real-time output power of the photovoltaic module in the photovoltaic air conditioner and the current real-time operating power of the photovoltaic air conditioner; when the current real-time output power is less than the current real-time operating power, executing the following first control mode: acquiring the current real-time frequency of the compressor of the photovoltaic air conditioner, reducing the current real-time frequency to obtain the current actual operating frequency; determining the current intermittent operating mode corresponding to the current actual operating frequency; when the current actual operating frequency is less than the oil return frequency threshold, and the interval time from the previous oil return reaches the interval time threshold, executing the oil return operation process, controlling the compressor to operate at the set oil return frequency; the interval time threshold is determined based on the continuous operating time in m consecutive intermittent operating modes.

Description

Technical Field

[0001] This invention belongs to the field of energy-saving air conditioning technology, specifically, it relates to a photovoltaic air conditioner and its oil return control method and control device. Background Technology

[0002] When an air conditioner is running, the compressor continuously circulates refrigerant oil and compressor oil through the pipeline, allowing the compressor to be lubricated by the returned oil. If the compressor cannot return oil properly, it is easy to cause insufficient lubrication of the compressor, which will aggravate wear. In severe cases, it may even cause the compressor to seize up, affecting the normal operation of the compressor and the air conditioner.

[0003] To address the issue of oil return in compressors, Chinese patent application CN114322267A discloses a control method for an air conditioner. When the operating frequency of the compressor is lower than the critical oil return frequency for a duration exceeding a preset time threshold, it is determined that the air conditioner requires oil return control. The target frequency and operating current of the compressor are determined, and the operating frequency of the compressor is adjusted according to the operating current to raise the operating frequency to the target frequency, thereby improving the oil return effect of the air conditioner.

[0004] Photovoltaic air conditioning, as an energy-saving technology, 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. However, the photovoltaic modules that provide power in photovoltaic air conditioning are greatly affected by sunlight. When sunlight is insufficient, the output power of the photovoltaic modules decreases. When the air conditioner relies solely on photovoltaic power, the output power of the photovoltaic modules may not be sufficient for the air conditioner to operate in the mode when there is sufficient power. In this case, it is usually necessary to control the compressor to operate at a reduced frequency. Furthermore, to avoid increased compressor wear caused by prolonged reduced-frequency operation, the duration of the reduced-frequency operation also needs to be controlled. Under these circumstances, both the compressor's operating frequency and continuous operating time will change. If existing technology is still used to control oil return by ensuring that the compressor's operating frequency is below the critical oil return frequency for a duration exceeding a preset time threshold, it is easy to lead to failure in oil return, resulting in low reliability of oil return control. Summary of the Invention

[0005] One of the objectives of this invention is to provide a method and device for controlling the oil return of a photovoltaic air conditioner, thereby improving the reliability of the oil return control in a photovoltaic air conditioner.

[0006] To achieve the above-mentioned objectives, the oil return control method for photovoltaic air conditioners provided by this invention adopts the following technical solution:

[0007] A photovoltaic air conditioning oil return control method, comprising:

[0008] Obtain the current real-time output power of the photovoltaic module in the photovoltaic air conditioner and the current real-time operating power of the photovoltaic air conditioner;

[0009] When the current real-time output power is less than the current real-time operating power, the first control mode is executed;

[0010] The first control mode includes:

[0011] 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;

[0012] 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.

[0013] When the current actual operating frequency is less than the oil return frequency threshold and the interval time from the previous oil return reaches the interval time threshold, the oil return operation process is executed, and the compressor is controlled to operate at the set oil return frequency; the interval time threshold is determined based on the continuous operating time in m consecutive intermittent operation modes.

[0014] In some embodiments of this application, the interval time threshold is determined based on the continuous running time in m consecutive intermittent running modes, specifically including:

[0015] Obtain the duration of each intermittent operation mode in the m consecutive intermittent operation modes, sum the m durations, and determine the sum as the interval time threshold.

[0016] In some embodiments of this application, the first control mode further includes:

[0017] Determine whether the oil return process is successful;

[0018] If so, reset the interval time to zero and restart the timer;

[0019] If not, the interval time continues to accumulate.

[0020] In some embodiments of this application, the first control mode further includes:

[0021] If the oil return process fails q times consecutively, a first prompt is issued, and then the photovoltaic air conditioner is shut down; the first prompt includes at least a prompt to restart the photovoltaic air conditioner when the set shutdown time is reached.

[0022] In some embodiments of this application, the first control mode further includes:

[0023] If the current actual operating frequency is not less than the oil return frequency threshold, 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.

[0024] In some embodiments of this application, the control method further includes:

[0025] When the current real-time output power is not less than the current real-time operating power, the second control mode is executed;

[0026] The second control mode includes:

[0027] The current real-time frequency of the compressor of the photovoltaic air conditioner is obtained. When the duration of the current real-time frequency being less than the oil return frequency threshold reaches the duration threshold, the oil return operation process is executed to control the compressor to run at the set oil return frequency.

[0028] In some embodiments of this application, the first control mode further includes:

[0029] Get the current number of times the frequency has been reduced;

[0030] When the current number of frequency reduction operations is less than a preset threshold, the process 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 is then performed.

[0031] In some embodiments of this application, the continuous running time in the intermittent operation mode is a variable value and is determined using the following formula:

[0032] T = k1 × f + k2 × n;

[0033] The downtime in the intermittent operation mode is a variable value and is determined using the following formula:

[0034] t = k3 × n;

[0035] Wherein, T is the continuous running time, t is the downtime, f is the current actual running frequency, n is the current number of frequency reduction runs, k1 is a known coefficient greater than 0, k2 is a known coefficient less than 0, and k3 is a known coefficient greater than 0.

[0036] To achieve the aforementioned objectives, the photovoltaic air conditioner oil return control device provided by this invention employs the following technical solution:

[0037] A photovoltaic air conditioner oil return control device, comprising:

[0038] The real-time output power acquisition unit is used to acquire the current real-time output power of the photovoltaic module in the photovoltaic air conditioner.

[0039] A real-time operating power acquisition unit is used to acquire the current real-time operating power of the photovoltaic air conditioner;

[0040] The execution unit is configured to execute a first control mode at least when the current real-time output power is less than the current real-time operating power;

[0041] The first control mode includes:

[0042] 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;

[0043] 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.

[0044] When the current actual operating frequency is less than the oil return frequency threshold and the interval time from the previous oil return reaches the interval time threshold, the oil return operation process is executed, and the compressor is controlled to operate at the set oil return frequency; the interval time threshold is determined based on the continuous operating time in m consecutive intermittent operation modes.

[0045] The present invention also provides a photovoltaic air conditioner, which includes the above-mentioned photovoltaic air conditioner oil return control device.

[0046] Compared with the prior art, the advantages and positive effects of the present invention are:

[0047] The photovoltaic air conditioner oil return control method and device provided by this invention, when the output power of the photovoltaic module is less than the operating power of the photovoltaic air conditioner, executes a first control mode of compressor frequency reduction operation, and determines an intermittent operation mode based on the actual operating frequency after frequency reduction. An interval time threshold is determined based on the continuous operating time in the intermittent operation mode, serving as a parameter for whether to execute the oil return process. When the actual operating frequency after frequency reduction is less than the oil return frequency threshold and the interval time since the last oil return reaches the interval time threshold, the oil return process is executed, controlling the compressor to operate at the set oil return frequency. By using the continuous operating time in the intermittent operation 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 oil return control, it can be ensured that the photovoltaic air conditioner can still smoothly enter the oil return process even in an 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, improving the rationality and reliability of the oil return control.

[0048] 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

[0049] 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 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.

[0050] Figure 1 A flowchart of an embodiment of the photovoltaic air conditioning oil return control method provided by the present invention;

[0051] Figure 2 A flowchart of another embodiment of the photovoltaic air conditioning oil return control method provided by the present invention;

[0052] Figure 3 This is a schematic diagram of one embodiment of the photovoltaic air conditioning oil return control device proposed in this invention. Implementation

[0053] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0054] 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.

[0055] First, the technical concept of this invention will be briefly described as follows:

[0056] Photovoltaic air conditioners typically use the photovoltaic (PV) power generated by PV modules to power the indoor and outdoor units of the air conditioning unit, maintaining the operation of the air conditioning system. Some PV air conditioners, in addition to using PV modules for power, are also connected to mains power. When the power output from the PV modules is insufficient, they can switch to mains power to ensure the normal operation of the air conditioning system. If the air conditioning system of a PV air conditioner only uses PV modules for power, or if it is connected to mains power but the mains power is unavailable, the PV air conditioner is an off-grid independent air conditioner. Because PV modules are greatly affected by sunlight, when sunlight is insufficient, the power output of the PV modules decreases, and the power they provide cannot meet the needs of the air conditioning system to operate in the mode when there is sufficient power. For this type of off-grid independent PV air conditioner, in order to keep the air conditioning system working, it is necessary to control the compressor to operate at a low frequency to reduce the power required by the air conditioning unit. At the same time, the low-frequency operation time of the compressor must also be adjusted to avoid the compressor running in a low-frequency state for a long time. That is, for PV air conditioners, when the output power of the PV modules is less than the operating power of the PV air conditioner, the operating frequency and continuous operating time of its compressor will change significantly. Therefore, the conventional method of controlling oil return by ensuring the compressor's operating frequency is below the critical oil return frequency for a duration exceeding a preset time threshold is not well-suited for photovoltaic (PV) air conditioners, potentially leading to oil return control failure. This is particularly problematic when the PV module's output power is less than the PV air conditioner's operating power. In light of this, this invention creatively proposes a novel PV air conditioner oil return control method. During the control process where the PV module's output power is less than the PV air conditioner's operating power, and the compressor frequency and operating time are adjusted, the method utilizes the continuous operating time in intermittent operation mode to determine the interval time threshold. The time interval between the previous oil return and reaching this threshold serves as a time reference for whether to execute oil return control. This ensures that the PV air conditioner can smoothly enter the oil return process even in intermittent operation modes with reduced frequency and insufficient continuous operating time, thus improving the reliability of PV air conditioner oil return control.

[0057] Figure 1 A flowchart of an embodiment of the photovoltaic air conditioning oil return control method proposed in this invention is shown.

[0058] like Figure 1 As shown, this embodiment uses the following process to achieve oil return control of photovoltaic air conditioner.

[0059] S11: Obtain the current real-time output power of the photovoltaic module in the photovoltaic air conditioner and the current real-time operating power of the photovoltaic air conditioner.

[0060] The current real-time output power refers to the output power of the photovoltaic module, which is obtained in real time according to the set sampling frequency; the current real-time operating power refers to the operating power required by the photovoltaic air conditioner, which is obtained in real time according to the set sampling frequency. The methods for obtaining the output power of the photovoltaic module and the real-time operating power of the photovoltaic air conditioner are implemented using existing technologies, and will not be described in detail here.

[0061] S12: When the current real-time output power is less than the current real-time operating power, execute the first control mode.

[0062] When the current real-time output power is less than the current real-time operating power, the output power provided by the photovoltaic module cannot meet the actual power demand of the photovoltaic air conditioner. When only the photovoltaic module is used for power supply, the photovoltaic air conditioner cannot operate according to the current real-time operating power; at the same time, its oil return control will be implemented in a specific manner. In this state, the photovoltaic air conditioner will be executed in the first control mode of S13-S15.

[0063] S13: Obtain the current real-time frequency of the compressor, reduce the current real-time frequency, and obtain the current actual operating frequency.

[0064] 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 determining the frequency obtained by subtracting a set frequency value from the current real-time frequency as the current actual operating frequency. The set frequency value can be a fixed frequency value or a variable frequency value.

[0065] S14: 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.

[0066] 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.

[0067] 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 S13, 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.

[0068] S15: When the current actual operating frequency is less than the oil return frequency threshold and the interval between the previous oil return reaches the interval time threshold, execute the oil return operation process and control the compressor to operate at the set oil return frequency.

[0069] The oil return frequency threshold is a preset value. If the actual operating efficiency of the compressor is less than this oil return frequency threshold, the compressor is prone to poor oil return.

[0070] The interval between the last oil return and the last return can be obtained by setting a timer.

[0071] 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, and the lower the probability of compressor oil return failure. 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.

[0072] In other embodiments, the interval time threshold is determined based on the duration of continuous operation in m consecutive intermittent operation modes, specifically including:

[0073] 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.

[0074] If the current actual operating frequency obtained by S14 is less than the oil return frequency threshold, and the interval time since the last oil return reaches the interval time threshold, the oil return operation process will be executed. Specifically, the compressor will be controlled to operate at the set oil return frequency. The set oil return frequency is a preset value, usually a frequency value higher than the oil return frequency threshold. When the compressor operates at this set oil return frequency, it can achieve a better oil return effect.

[0075] Figure 1 In this embodiment, when the output power of the photovoltaic module is less than the operating power of the photovoltaic air conditioner, a first control mode of compressor frequency reduction is executed. An intermittent operation mode is determined based on the actual operating frequency after frequency reduction, and an interval time threshold is determined based on the continuous operating time in the intermittent operation mode. This interval time threshold serves as a parameter for whether to execute the oil return process. When the actual operating frequency after frequency reduction is less than the oil return frequency threshold and the interval time since the last oil return reaches the interval time threshold, the oil return process is executed, and the compressor is controlled to operate at the set oil return frequency. Therefore, by using the continuous operating time in the intermittent operation 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 oil return control, it can be ensured that the photovoltaic air conditioner can still smoothly enter the oil return process even in an intermittent operating 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, improving the rationality and reliability of the oil return control.

[0076] Figure 2 A flowchart of another embodiment of the photovoltaic air conditioning oil return control method proposed in this invention is shown.

[0077] like Figure 2 As shown, this embodiment uses the following process to achieve oil return control of photovoltaic air conditioner.

[0078] S201: Obtain the current real-time output power P1 of the photovoltaic module in the photovoltaic air conditioner and the current real-time operating power P2 of the photovoltaic air conditioner.

[0079] For the meaning and acquisition method of current real-time output power and current real-time operating power, please refer to [link / reference]. Figure 1 Description of the embodiments.

[0080] S202: Determine whether P1≥P2 is satisfied. Based on the result, determine whether to execute S203 or S204.

[0081] S203: If S202 determines that P1≥P2, the second control mode will be executed.

[0082] Specifically, the second control mode includes: acquiring the current real-time frequency of the compressor of the photovoltaic air conditioner, and when the duration of the current real-time frequency being less than the oil return frequency threshold reaches the duration threshold, executing the oil return operation process and controlling the compressor to operate at the set oil return frequency.

[0083] For the meaning of return oil frequency threshold and set return oil frequency, please refer to [link / reference]. Figure 1 The relevant description of the embodiment. The duration threshold is a preset time threshold.

[0084] When the current real-time output power P1 of the photovoltaic module is not less than the current real-time operating power P2 of the photovoltaic air conditioner, the photovoltaic module can provide sufficient power 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. In this state, the condition for oil return control is that the duration for which the compressor's operating frequency is less than the oil return frequency is greater than a preset time threshold. When this oil return control condition is met, the oil return operation process is executed, and the compressor is controlled to operate at the set oil return frequency.

[0085] It should be understood that once the oil return is successful, the oil return control process will be terminated, and the compressor will operate at the normal target frequency.

[0086] S204: If S202 determines that P1≥P2 is not satisfied, that is, P1<P2, the first control mode will be executed, specifically, the process of S205-S217 will be executed.

[0087] S205: Obtain the current number of times the frequency is reduced and compare it with the preset number of times threshold.

[0088] The frequency reduction operation count is a preset parameter, and its value reflects the number of times the photovoltaic air conditioner reduces its frequency due to the current real-time output power being less than the current real-time operating power within a certain period of time. Its initial value is 0. When the condition of reducing the frequency due to the real-time output power being less than the real-time operating power is continuously met, its value will be incremented by 1 each time the condition is met; when the condition of reducing the frequency due to the real-time output power being less than the real-time operating power is not met, its count value will be reset to zero.

[0089] 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.

[0090] S206: Determine if the current number of frequency reduction operations exceeds a preset threshold. Execute S207 or S209 based on the determination result.

[0091] S207: If S206 determines that the current number of frequency reduction operations exceeds the preset threshold, a second prompt is issued. Then, S208 is executed.

[0092] S208: Controls the photovoltaic air conditioner to shut down.

[0093] If the number of times the frequency is reduced exceeds the preset threshold, it indicates that the photovoltaic air conditioner has repeatedly reduced its frequency because the current real-time output power is less than the current real-time operating power. 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.

[0094] Furthermore, a second prompt is issued before the photovoltaic air conditioner is shut down. This second prompt includes at least a low-power protection fault warning and a prompt to restart the photovoltaic air conditioner after the set shutdown time has been reached. Based on this prompt, the photovoltaic air conditioner user is informed of the shutdown fault and its cause, and a possible solution is provided: restart the photovoltaic air conditioner after the set shutdown time has been reached. If the sunlight conditions improve within the set shutdown time, the photovoltaic module can provide sufficient output power.

[0095] Furthermore, the second prompt is only issued when the current frequency reduction count exceeds a preset threshold, which can reduce the prompt frequency and avoid frequent prompts that would negatively impact the user experience.

[0096] It should be understood that after the photovoltaic air conditioner is turned off, the oil return process control also stops, and the timing time used to measure the oil return interval will also be reset to zero.

[0097] S209: If S206 determines that the current frequency reduction operation count is not greater than the preset count threshold, determine the current actual operating frequency, the current intermittent operation mode, and the interval time threshold.

[0098] In addition, during this process, the current frequency reduction operation count is incremented by 1 and stored as the frequency reduction operation count after the next photovoltaic air conditioner is turned on, so as to realize the automatic update of the frequency reduction operation count according to the actual frequency reduction operation status.

[0099] For the principles and implementation process of determining the current actual operating frequency, the current intermittent operating mode, and the interval time threshold, please refer to [link / reference needed]. Figure 1 The embodiments and other embodiments described above.

[0100] In some embodiments, the correspondence between the actual operating frequency and the intermittent operating mode is obtained and preset by the R&D personnel based on theoretical analysis and calculation, experimental analysis and verification, etc. The continuous operating time and downtime in the preset intermittent operating mode can be fixed values.

[0101] In some other embodiments, the continuous running time and downtime in the intermittent operation mode are both variable values.

[0102] 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.

[0103] 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.

[0104] S210: Determine whether the oil return condition is met, and execute S211 or S217 according to the determination result.

[0105] If the current actual operating frequency is less than the return oil frequency threshold and the interval between the last return oil return reaches the interval time threshold, then the return oil condition is met; otherwise, the return oil condition is not met.

[0106] S211: If S210 determines that the oil return condition is met, execute the oil return operation process and control the compressor to operate at the set oil return frequency. Then, continue to execute S212.

[0107] S212: Determine whether the oil return was successful, and execute S213 or S214 based on the result.

[0108] If the compressor operates at the set oil return frequency for the set duration, the oil return is considered successful; otherwise, the oil return is considered unsuccessful.

[0109] S213: If the oil return is successful, the interval time is reset to zero and the timer is restarted. Then, proceed to S210.

[0110] It should be understood that the interval timing process is only valid in the first control mode. That is, the interval timing is only performed in the first control mode.

[0111] S214: If the return oil fails, further determine whether the number of consecutive unsuccessful return oil attempts has reached the set number of unsuccessful attempts q, and execute S215 or S216 respectively according to the determination result.

[0112] The number of unsuccessful attempts, q, is set as a preset value.

[0113] S215: If the number of consecutive unsuccessful oil return attempts reaches the set number of unsuccessful attempts, issue the first prompt and control the photovoltaic air conditioner to shut down.

[0114] If the number of consecutive unsuccessful oil return attempts reaches the set number, it indicates that the photovoltaic module's output power is too low to meet the compressor's requirement to continuously operate at the set oil return frequency for the set duration. To avoid damage caused by unsuccessful compressor oil return, the photovoltaic air conditioner will be shut down. Furthermore, a first warning will be issued before shutting down the photovoltaic air conditioner. This first warning will at least include a prompt to restart the photovoltaic air conditioner after the set shutdown time has been reached, providing a solution to the oil return failure: restarting the photovoltaic air conditioner after the set shutdown time has elapsed. If the sunlight conditions improve within the set shutdown time, the photovoltaic module can provide sufficient output power, enabling effective compressor oil return control.

[0115] In some other embodiments, the first notification also includes a notification of an oil return failure, so that the photovoltaic air conditioner user is aware of the shutdown failure and cause of the photovoltaic air conditioner.

[0116] Furthermore, the first prompt is only issued when the number of consecutive unsuccessful oil return attempts reaches the set number, which can reduce the frequency of prompts and avoid frequent prompts that would negatively impact the user experience.

[0117] It should be understood that after the photovoltaic air conditioner is turned off, the oil return process control also stops, and the timing time used to measure the oil return interval will also be reset to zero.

[0118] S217: If the number of consecutive unsuccessful oil return attempts has not reached the set number of unsuccessful attempts, the interval time continues to accumulate. Then, proceed to S210.

[0119] S217: If S210 determines that the oil return condition is not met, control the operation of the photovoltaic air conditioner according to the current actual operating frequency and the current intermittent operation mode.

[0120] Specifically, after entering the first control mode, if the current actual operating frequency determined in process S209 is not less than the oil return frequency threshold, and / or the interval time from the previous oil return has not reached the interval time 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.

[0121] In some other embodiments, after the downtime of the photovoltaic air conditioner stops according to the current intermittent operation mode reaches the current downtime in the current intermittent operation mode, the photovoltaic air conditioner is controlled to start up. Then, the process of obtaining the current real-time output power and the current actual operating power and determining whether to execute the first control mode is executed again, so as to realize the cyclic automatic operation control of the photovoltaic air conditioner.

[0122] Figure 2 In the oil return control method of this embodiment, different oil return controls are executed when the photovoltaic module has different output power. Specifically, when the output power of the photovoltaic module is not less than the operating power of the photovoltaic air conditioner, oil return control is performed when the duration for which the compressor's operating frequency is less than the oil return frequency threshold reaches a preset duration threshold. When the output power of the photovoltaic module is less than the operating power of the photovoltaic air conditioner, an interval time threshold is determined by utilizing the continuous operating time in the intermittent operation mode. The time interval from the previous oil return reaches the interval time threshold as a time reference for whether to execute oil return control. This ensures that the photovoltaic air conditioner can still smoothly enter the oil return process even when operating in an intermittent working mode with reduced frequency and insufficient continuous operating time, thus 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, improving the rationality and reliability of the oil return control. Therefore, the oil return control of the photovoltaic air conditioner is more reasonable and reliable.

[0123] Furthermore, when the output power of the photovoltaic module is less than the operating power of the photovoltaic air conditioner, the compressor is not controlled to operate continuously at low frequency. Instead, the low-frequency operation time of the compressor is adjusted by setting the number of frequency reduction operations and intermittent operation modes, using different parameters and methods. Based on this method, controlling the photovoltaic air conditioner achieves two advantages: First, the compressor only reduces its frequency when the number of frequency reduction operations is less than a preset threshold, which reduces the compressor's frequency reduction time compared to existing technologies that indiscriminately reduce the compressor's frequency. Second, during frequency reduction operation, an intermittent operation mode corresponding to the actual operating frequency is used. The photovoltaic air conditioner runs for a period of time, then stops, and then restarts after a certain period of inactivity. The continuous operating time and the duration of the stop are closely related to the actual operating frequency, thus reasonably and reliably reducing the compressor's continuous low-frequency operation time. By adjusting the compressor's low-frequency operation time using different parameters and methods, the operation of the photovoltaic air conditioner can be maintained as much as possible while avoiding problems such as compressor wear, reduced reliability and lifespan of the compressor and photovoltaic air conditioning system, excessive noise, and loosening or even breakage of air conditioning pipes caused by prolonged low-frequency operation. This achieves a balance between the reliability of photovoltaic air conditioner operation and the comfort of using it.

[0124] Figure 3The diagram shows a structural schematic of an embodiment of the photovoltaic air conditioner oil return control device proposed in this invention, which realizes the oil return control of the photovoltaic air conditioner.

[0125] like Figure 3 As shown, the control device of this embodiment includes structural units, the functions of the structural units, and the relationships between them, as detailed below:

[0126] The control device includes:

[0127] The real-time output power acquisition unit 31 is used to acquire the current real-time output power of the photovoltaic module in the photovoltaic air conditioner.

[0128] The real-time operating power acquisition unit 32 is used to acquire the current real-time operating power of the photovoltaic air conditioner.

[0129] The execution unit 33 is used at least to execute the first control mode when the current real-time output power obtained by the real-time output power acquisition unit 31 is less than the current real-time operating power obtained by the real-time operating power acquisition unit 32.

[0130] The first control mode includes:

[0131] Obtain the current real-time frequency of the photovoltaic air conditioner's compressor, reduce the current real-time frequency to obtain the current actual operating frequency; determine the current intermittent operating mode corresponding to the current actual operating frequency based on the correspondence between the actual operating frequency and the intermittent operating mode; the intermittent operating mode includes at least continuous operating time and downtime; when the current actual operating frequency is less than the oil return frequency threshold and the interval time from the previous oil return reaches the interval time threshold, execute the oil return operation process and control the compressor to operate at the set oil return frequency; the interval time threshold is determined based on the continuous operating time in m consecutive intermittent operating modes.

[0132] The photovoltaic air conditioning oil return control device with the above structure runs the corresponding software program and performs the corresponding functions, according to... Figure 1 or Figure 2 The illustrated embodiment of the photovoltaic air conditioner oil return control method and its process are used to control the oil return of the photovoltaic air conditioner, achieving the corresponding technical effects as in the embodiment.

[0133] The photovoltaic air conditioner oil return control device described in the above embodiment is applied to a photovoltaic air conditioner to control the oil return of the photovoltaic air conditioner, thereby achieving the technical objective of improving the reliability of the photovoltaic air conditioner oil return control.

[0134] 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 conditioner oil return control method, characterized by, The control method comprises: acquiring a current real-time output power of a photovoltaic module in a photovoltaic air conditioner and a current real-time running power of the photovoltaic air conditioner; when the current real-time output power is less than the current real-time running power, executing a first control mode; the first control mode comprises: acquiring a current real-time frequency of a compressor of the photovoltaic air conditioner, reducing the current real-time frequency to obtain a current actual running frequency; according to a corresponding relationship between an actual running frequency and an intermittent running mode, determining a current intermittent running mode corresponding to the current actual running frequency; the intermittent running mode at least comprises a continuous running time and a shutdown time; when the current actual running frequency is less than an oil return frequency threshold value and an interval time from a previous oil return reaches an interval time threshold value, executing an oil return running process to control the compressor to run at a set oil return frequency; the interval time threshold value is determined according to the continuous running time in the continuous m intermittent running modes.

2. The photovoltaic air conditioner oil return control method of claim 1, wherein, the interval time threshold value is determined according to the continuous running time in the continuous m intermittent running modes, and specifically comprises: acquiring the continuous running time in each intermittent running mode in the continuous m intermittent running modes, summing up the m continuous running times, and determining the sum as the interval time threshold value.

3. The photovoltaic air conditioner oil return control method of claim 1, wherein, the first control mode further comprises: judging whether the oil return running process is successful; if yes, clearing the interval time and re-timing; if no, continuing to accumulate the interval time.

4. The photovoltaic air conditioner oil return control method of claim 3, wherein, the first control mode further comprises: if the oil return running process is unsuccessful for continuous q times, issuing a first prompt and then controlling the photovoltaic air conditioner to shut down; the first prompt at least comprises a prompt of controlling the photovoltaic air conditioner to start again when a set shutdown time is reached.

5. The photovoltaic air conditioner oil return control method of claim 1, wherein, the first control mode further comprises: if the current actual running frequency is not less than the oil return frequency threshold value and / or the interval time from the previous oil return does not reach the interval time threshold value, controlling the photovoltaic air conditioner to run according to the current actual running frequency and the current intermittent running mode.

6. The photovoltaic air conditioner oil return control method of claim 1, wherein, the control method further comprises: when the current real-time output power is not less than the current real-time running power, executing a second control mode; the second control mode comprises: acquiring a current real-time frequency of a compressor of the photovoltaic air conditioner, and when a duration of the current real-time frequency being less than the oil return frequency threshold value reaches a duration threshold value, executing an oil return running process to control the compressor to run at the set oil return frequency.

7. The photovoltaic air conditioner oil return control method of any one of claims 1 to 6, wherein, the first control mode further comprises: acquiring a current frequency reduction running number; when the current frequency reduction running number is less than a preset number threshold value, re-executing the process of acquiring a current real-time frequency of a compressor of the photovoltaic air conditioner, reducing the current real-time frequency to obtain a current actual running frequency.

8. The photovoltaic air conditioner oil return control method of claim 7, wherein, the continuous running time in the intermittent running mode is a variable value and is determined by the following formula: T=k1×f+k2×n; the shutdown time in the intermittent running mode is a variable value and is determined by the following formula: t=k3×n; Wherein, T is the continuous running time, t is the shutdown time, f is the current actual running frequency, n is the current frequency reduction operation times, k1 is a known coefficient greater than 0, k2 is a known coefficient less than 0, and k3 is a known coefficient greater than 0.

9. A photovoltaic air conditioner oil return control device, characterized by, The control device comprises: A real-time output power acquisition unit is configured to acquire a current real-time output power of a photovoltaic module in the photovoltaic air conditioner. A real-time running power acquisition unit is configured to acquire a current real-time running power of the photovoltaic air conditioner. An execution unit is configured to execute a first control mode when the current real-time output power is less than the current real-time running power. The first control mode comprises: Acquiring a current real-time frequency of a compressor of the photovoltaic air conditioner, reducing the current real-time frequency to obtain a current actual running frequency. According to a corresponding relationship between the actual running frequency and an intermittent running mode, a current intermittent running mode corresponding to the current actual running frequency is determined; the intermittent running mode at least comprises a continuous running time and a shutdown time. When the current actual running frequency is less than an oil return frequency threshold value and an interval time from a previous oil return reaches an interval time threshold value, an oil return running process is executed to control the compressor to run at a set oil return frequency; the interval time threshold value is determined according to the continuous running time in the continuous m intermittent running modes.

10. A photovoltaic air conditioner characterized by, The photovoltaic air conditioner comprises the oil return control device of the photovoltaic air conditioner according to claim 9.

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