Compressor overcurrent protection method and refrigerator

Abstract

The application discloses a kind of compressor overcurrent protection method and refrigerator, the compressor overcurrent protection method includes: according to the operating data of compressor, the rotational speed of the compressor is compared with the rated current relationship of construction;The current rotational speed of the compressor is detected, and the current rated current corresponding to the current rotational speed is obtained according to the comparison relationship;Current rated current is set overcurrent protection value, and whether the compressor appears overcurrent fault is judged according to the size relationship between the input current of the compressor and overcurrent protection value.Compared with prior art, the rated current of the compressor under different rotational speeds can be determined, and the overcurrent protection value under the rotational speed is obtained, whether the compressor appears overcurrent fault is judged by real-time detection of the input current of the compressor, and the operating reliability of the compressor is improved.

Description

Technical Field

[0001] This invention relates to the field of compressor control, and in particular to a compressor overcurrent protection method and a refrigerator. Background Technology

[0002] When a refrigerator has problems such as a dirty condenser, excessively high ambient temperature, or carbon buildup on the compressor pump valve plates, its input current will exceed the rated current, resulting in overcurrent. If it operates under overcurrent for a long time, the compressor may burn out due to overheating.

[0003] Existing overcurrent protection methods typically involve setting an overcurrent protection value through variable frequency drive software. This value is empirically derived based on the compressor's displacement, and to prevent malfunctions, it is often set too high. However, compressor operating parameters (such as speed) vary under different operating conditions, and the compressor's rated current also differs at different speeds. This causes the overcurrent protection value to change. If a fixed (too high) overcurrent protection value is set using existing technologies, the reliability of using this value to determine whether an overcurrent fault has occurred when the compressor's operating conditions change will decrease. This could lead to situations where an overcurrent has occurred but cannot be detected.

[0004] Therefore, how to design a compressor overcurrent protection method and a refrigerator that can set overcurrent protection values ​​according to different operating conditions of the compressor, thereby improving the operating reliability of the compressor, is a technical problem that the industry urgently needs to solve. Summary of the Invention

[0005] In view of the problem that the reliability of the judgment result is low when using a fixed overcurrent protection value to determine whether the compressor has an overcurrent fault in the existing technology, this invention proposes a compressor overcurrent protection method and a refrigerator.

[0006] The technical solution of this invention is to propose a compressor overcurrent protection method, comprising:

[0007] Based on the compressor's operating data, a correlation between the compressor's speed and rated current is established;

[0008] The current speed of the compressor is detected, and the current rated current corresponding to the current speed is obtained according to the reference relationship;

[0009] The overcurrent protection value is set according to the current rated current, and the compressor is judged to have an overcurrent fault based on the relationship between the compressor's input current and the overcurrent protection value.

[0010] Furthermore, based on the compressor's operating data, a correlation is established between the compressor's speed and rated current, including:

[0011] The compressor is controlled to jump from its lowest speed to its highest speed by a preset speed range.

[0012] Record the rated current after each change in the compressor's speed;

[0013] The correlation was constructed based on the recorded rated current and compressor speed.

[0014] Furthermore, the overcurrent protection value is set according to the current rated current, including:

[0015] The overcurrent protection value is set to a preset multiple of the current rated current;

[0016] When the compressor's running time exceeds a first preset time, the preset factor is reduced.

[0017] When the compressor's operating time is less than the second preset time, the preset multiplier is increased.

[0018] Furthermore, determining whether the compressor has an overcurrent fault based on the relationship between the compressor's input current and the overcurrent protection value includes:

[0019] Determine whether the input current of the compressor is greater than the overcurrent protection value;

[0020] If so, the compressor is determined to have an overcurrent fault.

[0021] Furthermore, when the compressor speed is within the first speed range, determining whether the compressor has an overcurrent fault based on the relationship between the compressor's input current and the overcurrent protection value also includes:

[0022] When the input current of the compressor is less than the overcurrent protection value, the speed of the compressor is increased, and the input current of the compressor is re-evaluated to see if it is greater than the overcurrent protection value.

[0023] If so, the compressor is determined to have an overcurrent fault;

[0024] If not, then when the compressor temperature is higher than the first threshold temperature, it is determined that the compressor has an overcurrent fault.

[0025] Furthermore, when the compressor speed is within the second speed range, determining whether the compressor has an overcurrent fault based on the relationship between the compressor's input current and the overcurrent protection value also includes:

[0026] When the input current of the compressor is less than the overcurrent protection value, the speed of the compressor is reduced, and the input current of the compressor is re-evaluated to see if it is greater than the overcurrent protection value.

[0027] If so, the compressor is determined to have an overcurrent fault;

[0028] If not, then when the compressor temperature is higher than the second threshold temperature, it is determined that the compressor has an overcurrent fault.

[0029] Furthermore, the first speed range is 1200RPM~3600RPM, and the second speed range is 3600RPM~4500RPM.

[0030] Furthermore, before determining whether the compressor has an overcurrent fault based on the relationship between the compressor's input current and the overcurrent protection value, the compressor overcurrent protection method further includes: sampling the compressor's input current using a sliding window algorithm;

[0031] The sliding window algorithm is set to a window length of 10 sampling points.

[0032] Furthermore, when it is determined that the compressor has an overcurrent fault, the compressor overcurrent protection method further includes:

[0033] Determine whether the duration for which the input current is greater than the overcurrent protection value has reached a third preset time;

[0034] If so, then a shutdown operation will be performed on the compressor.

[0035] The present invention also proposes a refrigerator having a compressor and a controller, wherein the controller performs the above-described compressor overcurrent protection control method.

[0036] Compared with the prior art, the present invention has at least the following beneficial effects:

[0037] In this invention, the overcurrent protection value of the compressor is set according to the current speed of the compressor, so that the overcurrent protection value set in this invention can adapt to different operating conditions of the compressor. This avoids the problem of low reliability of overcurrent fault judgment results caused by setting a single fixed overcurrent protection value, thus solving the overcurrent protection problem of the compressor and extending the service life of the compressor. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is an overall flowchart of the overcurrent protection method of the present invention;

[0040] Figure 2 This is a flowchart illustrating how the compressor of the present invention determines whether an overcurrent fault has occurred at the current speed.

[0041] Figure 3 A flowchart illustrating the overcurrent protection value settings in this invention;

[0042] Figure 4 This is a flowchart illustrating how to determine whether an overcurrent fault has occurred in the compressor when the compressor speed is within the first speed range, as described in this invention.

[0043] Figure 5 This is a flowchart illustrating how to determine whether an overcurrent fault has occurred in the compressor when the compressor speed is in the second speed range in this invention.

[0044] Figure 6 This is a flowchart of the input current sampling process in this invention. Detailed Implementation

[0045] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0046] Therefore, a feature pointed out in this specification is used to describe one feature of one embodiment of the invention, and does not imply that every embodiment of the invention must have the described feature. Furthermore, it should be noted that this specification describes many features. Although certain features may be combined to illustrate possible system designs, these features may also be used in other combinations not explicitly stated. Therefore, unless otherwise stated, the described combinations are not intended to be limiting.

[0047] The principles and structure of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0048] Prolonged overcurrent operation of a compressor can lead to overheating and burnout. Existing overcurrent protection schemes typically use variable frequency drive software to set a fixed overcurrent protection value. The compressor's input current is then used to determine if an overcurrent fault has occurred. To prevent false alarms, this protection value is usually set relatively high. However, the compressor's rated current varies under different operating conditions, and the corresponding overcurrent protection value will also change. Relying solely on a fixed overcurrent protection value to determine the presence of an overcurrent fault will result in unreliable judgments.

[0049] To address the above problems, this invention proposes a compressor overcurrent protection method. Please refer to [link / reference]. Figure 1 It includes the following steps:

[0050] Based on the compressor's operating data, a correlation was established between the compressor's speed and rated current.

[0051] Detect the current speed of the compressor and obtain the current rated current corresponding to the current speed according to the reference relationship;

[0052] Set the overcurrent protection value according to the current rated current, and determine whether the compressor has an overcurrent fault based on the relationship between the compressor's input current and the overcurrent protection value.

[0053] As can be seen from the above steps, the overcurrent protection value is set based on the current rated current, which in turn is determined based on the current rotational speed. Therefore, the overcurrent protection value set in this invention is actually matched to the current rotational speed. The compressor's current rotational speed also corresponds to different operating conditions of the compressor. Thus, the overcurrent protection value set in this invention is actually matched to the compressor's operating conditions, enabling the invention to obtain an appropriate overcurrent protection value for each operating condition.

[0054] By setting the overcurrent protection value according to this scheme, the reliability of overcurrent fault judgment can be reduced by setting a single fixed overcurrent protection value.

[0055] It should be noted that the compressor operating data here can be historical operating data of the compressor, by obtaining the historical data of the compressor to summarize the relationship between the compressor speed and the rated current, or it can be experimental data before the relationship is established, by adjusting the current speed of the compressor in advance to change the operating conditions of the compressor, conducting multiple experiments and recording data to obtain the above relationship.

[0056] The above-mentioned operating data in this invention is derived from the implementation data. It is obtained by controlling the compressor to operate at multiple different speeds and recording the corresponding rated current.

[0057] Specifically, based on the compressor's operating data, a correlation is established between the compressor's speed and rated current, including:

[0058] The compressor is controlled to gradually transition from its lowest speed to its highest speed by a preset speed range.

[0059] Record the rated current after each change in compressor speed;

[0060] A correlation was established based on the recorded rated current and compressor speed.

[0061] Here, "jump operation" means controlling the compressor to run at different speeds. In this invention, the jump operation starts from the lowest speed of the compressor. Each time the compressor runs, its speed increases by a preset speed increment compared to the previous run, until the compressor reaches its maximum speed.

[0062] In a specific embodiment of the present invention, the minimum speed of the compressor is 1200 RPM, the maximum speed of the compressor is 4500 RPM, and the preset speed amplitude is set to 30 RPM. Accordingly, the jump operation mode in the present invention can be:

[0063] The compressor is controlled to run at an initial speed of 1200 RPM. Then, it is controlled to run at 1230 RPM for the second time, 1260 RPM for the third time, 1290 RPM for the fourth time, and so on. Each time the compressor is controlled to run at an initial speed, the speed is increased by 30 RPM compared to the previous time, until the compressor runs at 4500 RPM, and then the above control is stopped.

[0064] The preset speed amplitude can be set according to actual measurement needs. If a more accurate value is needed, the preset speed amplitude can be appropriately reduced. At this time, the speed of the compressor each time it runs is less different from the previous speed, but the corresponding detection quantity will also increase after the preset speed amplitude is reduced.

[0065] During the aforementioned jump-operation control, the rated current needs to be recorded after each speed jump of the compressor to obtain the correlation between the compressor speed and the rated current. For example, when the compressor is running at 1200 RPM, the rated current is recorded once; when the compressor is running at 1230 RPM, the rated current is recorded again, and so on until the compressor is running at 4500 RPM, at which point the rated current is recorded once more. In this way, a rated current can be obtained for each speed of the compressor, and this correspondence is the correlation relationship described above.

[0066] Based on this comparison relationship, when the present invention performs control in the subsequent process, after obtaining the current speed of the compressor, it can obtain a current rated current corresponding to the current speed, which can then be used to set the overcurrent protection value of the compressor at the current speed.

[0067] Based on the above settings, the present invention can obtain the above-mentioned comparison relationship, which can reflect the rated current corresponding to most of the compressor's speeds. Therefore, after obtaining the current speed, the present invention can set a matching overcurrent protection value, and this overcurrent protection value has been verified by the aforementioned jump operation, making it more reliable.

[0068] In some other embodiments of the present invention, in order to obtain a more detailed comparison relationship, a corresponding fitting curve can be generated by using multiple sets of comparison parameters of the compressor speed and rated current, and the regression equation of the fitting curve can be obtained. In this way, even if the current speed of the compressor does not have a direct corresponding data in the previously recorded multiple sets of data, the rated current with high reliability corresponding to the current speed can be obtained by using the regression equation.

[0069] After obtaining the above correlation, the current rated current can be determined based on the compressor's current speed. Then, by detecting the compressor's input current, it can be determined whether the compressor has an overcurrent fault. Please refer to [link / reference]. Figure 2 This is the flowchart corresponding to this part of the logic. The determination of the current rated current is that after obtaining the current speed of the compressor, the corresponding current rated current is obtained according to the corresponding relationship.

[0070] Then the input current is checked, which is the compressor's input current.

[0071] Finally, the current comparison judgment is performed. In this process, the overcurrent protection value needs to be determined based on the current rated current. Then, the compressor is judged to have an overcurrent fault by comparing the input current and the overcurrent protection value.

[0072] Through the above solution, the present invention can solve the overcurrent protection problem of the compressor and extend the service life of the compressor.

[0073] Furthermore, the overcurrent protection value is set according to the current rated current in this invention, including:

[0074] Set the overcurrent protection value to a preset multiple of the current rated circuit;

[0075] If the compressor's running time exceeds the first preset time, the preset multiplier is reduced.

[0076] When the compressor's running time is less than the second preset time, the preset multiplier is increased.

[0077] Here, lowering the preset multiplier means reducing the overcurrent protection value, and increasing the preset multiplier means increasing the overcurrent protection value. In this invention, the overcurrent protection value is adjusted according to the running time because the compressor's input current will be relatively high when the compressor is in the initial stage of startup or when the load is large. This is a normal phenomenon, and the overcurrent protection value can be appropriately increased to avoid misjudgment at this time. However, when the compressor has been running for a long time, the compressor operation is relatively stable, and the compressor's input current tends to be stable. Under normal circumstances, the input current at this time will be close to the rated current, so the overcurrent protection value can be appropriately reduced.

[0078] Therefore, based on the above, the present invention reduces the overcurrent protection value when the compressor's running time is greater than the first preset time, and increases the overcurrent protection value when the compressor's running time is less than the second preset time.

[0079] In a preferred embodiment of the present invention, the preset multiple is set to 1.6. In the prior art, the overcurrent protection value is also set according to the rated current, which is generally set to 1.5 to 2 times the rated current.

[0080] In this invention, the preset multiple is set to 1.6, which is a common compromise value. At this preset multiple, it can effectively prevent damage caused by sudden load changes or internal faults, and will not be too sensitive to affect the normal use of the compressor.

[0081] The first preset time is set to 6 hours, and the second preset time is set to 30 minutes. When the compressor runs for more than 6 hours, the preset multiplier can be reduced to 1.4. When the compressor runs for less than 30 minutes, the preset multiplier can be increased to 1.7.

[0082] Based on the above logic, the process of setting the overcurrent protection value in this invention can be as follows: first, obtain the current speed of the compressor, and then obtain the current rated current corresponding to the current speed according to the reference relationship. Here, the current rated current is set to Ix. When the compressor's running time is within 30 minutes, the overcurrent protection value can be set to 1.4Ix.

[0083] Then, when the compressor runs for more than 30 minutes but less than 6 hours, set the overcurrent protection value to 1.6Ix;

[0084] Finally, when the compressor runs for more than 6 hours, the overcurrent protection value is set to 1.7Ix;

[0085] Please see Figure 3 The specific process for setting the overcurrent protection value in this invention is as follows: First, the running time of the compressor is determined. Then, it is determined whether the running time of the compressor is less than a first preset time. If so, the overcurrent protection value is increased. If not, it is determined whether the running time of the compressor is greater than a second preset time. If so, the overcurrent protection value is adjusted.

[0086] Based on this configuration, the present invention can further improve the intelligence level of overcurrent protection and reduce the false alarm rate.

[0087] Furthermore, in this invention, determining whether the compressor has an overcurrent protection fault based on the relationship between the compressor's input current and the overcurrent protection value includes:

[0088] Determine if the compressor's input current exceeds the overcurrent protection value;

[0089] If so, the compressor is determined to have an overcurrent fault.

[0090] Based on these steps, the present invention can accurately determine whether the compressor has an overcurrent fault, thus solving the overcurrent protection problem of the compressor and extending its service life.

[0091] As mentioned above, the overcurrent protection value of the compressor in this invention is actually set based on the compressor speed. To avoid potential abnormalities at different speeds, after determining the overcurrent protection value, if it is determined that the compressor is operating normally within the current speed range, the compressor speed is also adjusted to prevent the occurrence of the potential abnormality. If the compressor input current is still less than the overcurrent protection value after the compressor speed adjustment, the compressor can be considered to be operating normally. Otherwise, it indicates that there may be a potential fault and an early warning is required.

[0092] Specifically, in this invention, the compressor speed range is divided into a first speed range and a second speed range. Then, different compressor speed adjustment methods are executed in the first speed range and the second speed range respectively to avoid the above-mentioned potential abnormal situations. Here, the first speed range is set to 1200RPM~3600RPM and the second speed range is 3600RPM~4500RPM.

[0093] This setting is because when the compressor is at around 3600 RPM, it is the safe operating speed for most household inverter compressors, and it is also the optimal operating range for the compressor under inverter control, which can balance cooling capacity and energy consumption performance.

[0094] When the compressor is running at a low speed, less than 3600 RPM, the rated current of the compressor is relatively low, and the operating state can be optimized by increasing the compressor speed.

[0095] When the compressor is running at a high speed, greater than 3600 RPM, it indicates that the compressor may have entered a high load or high energy consumption state. At this time, more stringent control measures are required, such as reducing the compressor speed and detecting changes in the rated current.

[0096] Therefore, this invention divides the compressor's speed range into a first speed range and a second speed range with 3600 RPM as the boundary, and then executes different speed adjustment schemes in different speed ranges, which can optimize the compressor's operating state to a certain extent.

[0097] Please see Figure 4 In this invention, when the compressor speed is within the first speed range, the method for determining whether the compressor has an overcurrent fault based on the relationship between the compressor's input current and the overcurrent protection value also includes:

[0098] When the compressor's input current is less than the overcurrent protection value, increase the compressor's speed and re-evaluate whether the compressor's input current is greater than the overcurrent protection value.

[0099] If so, then the compressor is determined to have an overcurrent fault;

[0100] If not, then if the compressor temperature is higher than the first threshold temperature, the compressor is determined to have an overcurrent fault.

[0101] Please see Figure 5 In this invention, when the compressor speed is in the second speed range, the method for determining whether the compressor has an overcurrent fault based on the relationship between the compressor's input current and the overcurrent protection value also includes:

[0102] When the compressor's input current is less than the overcurrent protection value, reduce the compressor's speed and re-evaluate whether the compressor's input current is greater than the overcurrent protection value.

[0103] If so, then the compressor is determined to have an overcurrent fault;

[0104] If not, then if the compressor temperature is higher than the second threshold temperature, the compressor is determined to have an overcurrent fault.

[0105] This invention, by adjusting the compressor speed within the first and second speed ranges when the input current is less than the overcurrent protection value and making further judgments, can avoid whether the compressor is experiencing momentary fluctuations or continuous overload. Furthermore, by combining the compressor temperature with the above judgments, the accuracy of overcurrent fault judgment can be further guaranteed.

[0106] The first and second threshold temperatures are set according to the actual operating conditions of the compressor, and are generally set at 80~90 degrees Celsius.

[0107] Please see Figure 6 Before determining whether the compressor has an overcurrent fault based on the relationship between the compressor's input current and the overcurrent protection value, the compressor overcurrent protection method in this invention further includes: sampling the compressor's input current using a sliding window algorithm;

[0108] The sliding window algorithm sets the window length to 10 sampling points.

[0109] In this invention, a sliding window algorithm is used to smooth the input current sampling data during the input current detection stage, which can avoid misjudgments caused by instantaneous current fluctuations. The window length is set to 10 sampling points, and the average value is taken as the current input current, thereby improving the stability and reliability of the judgment.

[0110] Furthermore, when an overcurrent fault is determined in the compressor, the compressor overcurrent protection method of the present invention further includes:

[0111] Determine whether the duration for which the input current exceeds the overcurrent protection value has reached the third preset time;

[0112] If so, the compressor will be shut down.

[0113] This part of the invention is designed to set a shutdown delay judgment mechanism when the compressor needs to be shut down due to overcurrent protection. The shutdown operation is only performed after the current has been continuously exceeding a third preset time, so as to avoid malfunctions caused by momentary interference.

[0114] In a preferred embodiment of the present invention, the third preset time can be set to 3 seconds.

[0115] The present invention also proposes a refrigerator having a compressor and a controller, the controller performing the above-described compressor overcurrent protection method.

[0116] Compared with the prior art, the present invention has at least the following beneficial effects:

[0117] In this invention, the overcurrent protection value of the compressor is set according to the current speed of the compressor, so that the overcurrent protection value set in this invention can adapt to different operating conditions of the compressor. This avoids the problem of low reliability of overcurrent fault judgment results caused by setting a single fixed overcurrent protection value, thus solving the overcurrent protection problem of the compressor and extending the service life of the compressor.

[0118] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A compressor overcurrent protection method, characterized in that, include: Based on the compressor's operating data, a correlation between the compressor's speed and rated current is established; The current speed of the compressor is detected, and the current rated current corresponding to the current speed is obtained according to the reference relationship; The overcurrent protection value is set according to the current rated current, and the compressor is judged to have an overcurrent fault based on the relationship between the compressor's input current and the overcurrent protection value. When the compressor speed is within the first speed range, determining whether the compressor has an overcurrent fault based on the relationship between the compressor's input current and the overcurrent protection value also includes: When the input current of the compressor is less than the overcurrent protection value, the speed of the compressor is increased, and the input current of the compressor is re-evaluated to see if it is greater than the overcurrent protection value. If so, the compressor is determined to have an overcurrent fault; If not, then when the compressor temperature is higher than the first threshold temperature, it is determined that the compressor has an overcurrent fault.

2. The compressor overcurrent protection method according to claim 1, characterized in that, Based on the compressor's operating data, a correlation is established between the compressor's speed and rated current, including: The compressor is controlled to jump from its lowest speed to its highest speed by a preset speed range. Record the rated current after each change in the compressor's speed; The correlation was constructed based on the recorded rated current and compressor speed.

3. The compressor overcurrent protection method according to claim 1, characterized in that, Set the overcurrent protection value according to the current rated current, including: The overcurrent protection value is set to a preset multiple of the current rated current; When the compressor's running time exceeds a first preset time, the preset factor is reduced. When the compressor's operating time is less than the second preset time, the preset multiplier is increased.

4. The compressor overcurrent protection method according to claim 1, characterized in that, Determining whether the compressor has an overcurrent fault based on the relationship between the compressor's input current and the overcurrent protection value includes: Determine whether the input current of the compressor is greater than the overcurrent protection value; If so, the compressor is determined to have an overcurrent fault.

5. The compressor overcurrent protection method according to claim 1, characterized in that, When the compressor speed is in the second speed range, determining whether the compressor has an overcurrent fault based on the relationship between the compressor's input current and the overcurrent protection value also includes: When the input current of the compressor is less than the overcurrent protection value, the speed of the compressor is reduced, and the input current of the compressor is re-evaluated to see if it is greater than the overcurrent protection value. If so, the compressor is determined to have an overcurrent fault; If not, then when the compressor temperature is higher than the second threshold temperature, it is determined that the compressor has an overcurrent fault.

6. The compressor overcurrent protection method according to claim 5, characterized in that, The first speed range is 1200RPM~3600RPM, and the second speed range is 3600RPM~4500RPM.

7. The compressor overcurrent protection method according to claim 1, characterized in that, Before determining whether the compressor has an overcurrent fault based on the relationship between the compressor's input current and the overcurrent protection value, the compressor overcurrent protection method further includes: sampling the compressor's input current using a sliding window algorithm; The sliding window algorithm is set to a window length of 10 sampling points.

8. The compressor overcurrent protection method according to claim 4, characterized in that, When it is determined that the compressor has an overcurrent fault, the compressor overcurrent protection method further includes: Determine whether the duration for which the input current is greater than the overcurrent protection value has reached a third preset time; If so, then a shutdown operation will be performed on the compressor.

9. A refrigerator having a compressor and a controller, the controller performing the compressor overcurrent protection method as described in any one of claims 1 to 8.

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