Frequency converter overcurrent suppression method and device, motor control system and storage medium

Abstract

The invention discloses a frequency converter overcurrent suppression method and device, a motor control system and a storage medium, and relates to the technical field of motor control, and the frequency converter overcurrent suppression method comprises the steps: obtaining a difference value between a three-phase current effective value of a motor controlled by a frequency converter and a preset current amplitude limiting value, and obtaining a current error; under the condition that the current error is greater than zero, determining a target reduction amount of a torque current instruction output to the motor by the frequency converter according to the current error; the current error is positively correlated with the target reduction amount; and according to the target reduction amount, reducing the instruction value of the torque current instruction to obtain a target torque current instruction, and controlling the motor to operate according to the target torque current instruction. The safety and reliability of the frequency converter and the motor can be improved.

Description

Technical Field

[0001] This application relates to the field of motor control technology, and in particular to a method, device, motor control system and storage medium for suppressing overcurrent in a frequency converter. Background Technology

[0002] A frequency converter is an electronic device used to regulate the speed of a motor. It converts the power supply frequency into a frequency suitable for the motor. In industrial production, frequency converters are widely used in motor control systems to achieve precise motor control, thereby improving production efficiency and quality.

[0003] However, during the use of frequency converters, overcurrent problems may occur due to factors such as circuit design, motor parameter design, and changes in motor load. Overcurrent in frequency converters can damage both the frequency converter and the motor it controls, thereby affecting the safety and reliability of both the frequency converter and the motor. Summary of the Invention

[0004] The main objective of this application is to provide a method, device, motor control system, and storage medium for suppressing overcurrent in a frequency converter, aiming to improve the safety and reliability of the frequency converter and the motor.

[0005] To achieve the above objectives, this application provides an overcurrent suppression method for a frequency converter, the method comprising:

[0006] The difference between the effective value of the three-phase current of the motor controlled by the frequency converter and the preset current limit value is used to obtain the current error.

[0007] When the current error is greater than zero, the target reduction amount of the torque current command output by the frequency converter to the motor is determined based on the current error; the current error is positively correlated with the target reduction amount.

[0008] Based on the target reduction amount, the command value of the torque current command is reduced to obtain the target torque current command, and the motor is controlled to run according to the target torque current command.

[0009] In one embodiment, the step of determining the target reduction amount of the torque current command output by the frequency converter to the motor based on the current error includes:

[0010] The target reduction amount of the torque current command is obtained by multiplying the current error by a preset reduction ratio coefficient. The reduction ratio coefficient is greater than zero and less than or equal to a preset coefficient threshold.

[0011] In one embodiment, the step of reducing the command value of the torque current command according to the target reduction amount to obtain the target torque current command includes:

[0012] The target reduction amount is limited to obtain the limited target reduction amount;

[0013] Based on the target reduction amount after limiting, the command value of the torque current command is reduced to obtain the target torque current command.

[0014] In one embodiment, the step of determining the target reduction amount of the torque current command output by the frequency converter to the motor based on the current error includes:

[0015] Using the current error as an index, the reduction amount corresponding to the current error is found in a preset relationship table and used as the target reduction amount of the torque current command.

[0016] In one embodiment, before the step of reducing the command value of the torque current command according to the target reduction amount to obtain the target torque current command, the method further includes:

[0017] Determine whether the target reduction amount is greater than a preset reduction amount threshold;

[0018] If the target reduction amount is greater than the preset reduction amount threshold, the command value of the torque current command is reduced according to the preset reduction amount threshold to obtain the target torque current command;

[0019] If the target reduction amount is less than or equal to the preset reduction amount threshold, the step of reducing the torque current command value according to the target reduction amount to obtain the target torque current command is executed.

[0020] In one embodiment, prior to the step of controlling the motor to operate according to the target torque current command, the method further includes:

[0021] Determine whether the command value of the target torque current command is less than a preset command threshold;

[0022] If the command value of the target torque current command is less than the preset command threshold, the command value of the target torque current command is adjusted to the preset command threshold, and the motor is controlled to run according to the adjusted target torque current command.

[0023] If the command value of the target torque current command is greater than or equal to the preset command threshold, the step of controlling the motor to run according to the target torque current command is executed.

[0024] In one embodiment, the step of reducing the command value of the torque current command according to the target reduction amount to obtain the target torque current command includes:

[0025] If the command value of the torque current command is greater than zero, the command value of the torque current command is reduced by subtracting the command value of the torque current command from the target reduction amount, thereby obtaining the target torque current command;

[0026] If the command value of the torque current command is less than zero, the command value of the torque current command is reduced by adding the command value of the torque current command to the target reduction amount, thereby obtaining the target torque current command.

[0027] Furthermore, to achieve the above objectives, this application also provides an inverter overcurrent suppression device, the device comprising:

[0028] The data acquisition module is used to acquire the effective value of the three-phase current of the motor controlled by the frequency converter and the difference between it and the preset current limit value to obtain the current error.

[0029] The data processing module is used to determine, based on the current error, the target reduction amount of the torque current command output by the frequency converter to the motor when the current error is greater than zero; the current error is positively correlated with the target reduction amount.

[0030] The overcurrent suppression module is used to reduce the command value of the torque current command according to the target reduction amount, obtain the target torque current command, and control the motor to run according to the target torque current command.

[0031] In addition, to achieve the above objectives, this application also provides a motor control system, which includes a frequency converter and a motor, and is used to implement the steps of the frequency converter overcurrent suppression method described above.

[0032] In addition, to achieve the above objectives, this application also provides a storage medium, which is a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, it implements the steps of the inverter overcurrent suppression method as described above.

[0033] In addition, to achieve the above objectives, this application also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the inverter overcurrent suppression method described above.

[0034] This application provides an overcurrent suppression method for a frequency converter. First, the effective value of the three-phase current of the motor controlled by the frequency converter is obtained, and the difference between it and the preset current limit value is used to obtain the current error. If the current error is greater than zero, it indicates that there is a risk of overcurrent in the frequency converter. Then, based on the current error, the target reduction amount of the torque current command output by the frequency converter to the motor can be determined. The current error is positively correlated with the target reduction amount. Then, based on the target reduction amount, the command value of the torque current command is reduced to obtain the target torque current command, and the motor is controlled to run according to the target torque current command.

[0035] Therefore, when there is a risk of overcurrent in the frequency converter, this application appropriately reduces the torque current command value output by the frequency converter to the motor based on the current error. The adjusted torque current command effectively controls the three-phase current output of the motor within a relatively safe range, thereby avoiding overcurrent problems in the frequency converter and improving the safety and reliability of both the frequency converter and the motor. Attached Figure Description

[0036] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0037] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 A schematic flowchart of the inverter overcurrent suppression method provided in the first embodiment of this application;

[0039] Figure 2 This is a schematic diagram of the overall process of the inverter overcurrent suppression method provided in the embodiments of this application;

[0040] Figure 3 This is a schematic diagram illustrating the control principle of the inverter overcurrent suppression method provided in the embodiments of this application;

[0041] Figure 4 This is a schematic diagram of the current waveform before overcurrent suppression provided in an embodiment of this application;

[0042] Figure 5 This is a schematic diagram of the current waveform after overcurrent suppression provided in an embodiment of this application;

[0043] Figure 6 This is a schematic diagram of the module structure of the inverter overcurrent suppression device involved in the embodiments of this application;

[0044] Figure 7This is a schematic diagram of the module structure of the motor control system involved in the embodiments of this application.

[0045] The purpose, features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0046] It should be understood that the specific embodiments described herein are merely illustrative of the technical solutions of this application and are not intended to limit this application.

[0047] To better understand the technical solution of this application, a detailed description will be provided below in conjunction with the accompanying drawings and specific implementation methods.

[0048] A frequency converter is an electronic device used to regulate the speed of a motor. It converts the power supply frequency into a frequency suitable for the motor. In industrial production, frequency converters are widely used in motor control systems to achieve precise motor control, thereby improving production efficiency and quality.

[0049] However, during the use of frequency converters, overcurrent problems may occur due to factors such as circuit design, motor parameter design, and changes in motor load. Overcurrent in frequency converters can damage both the frequency converter and the motor it controls, thereby affecting the safety and reliability of both the frequency converter and the motor.

[0050] Based on this, this application provides an overcurrent suppression method for frequency converters. First, the effective value of the three-phase current of the motor controlled by the frequency converter is obtained, and the difference between it and the preset current limit value is used to obtain the current error. If the current error is greater than zero, it indicates that there is a risk of overcurrent in the frequency converter. Then, based on the current error, the target reduction amount of the torque current command output by the frequency converter to the motor can be determined. The current error is positively correlated with the target reduction amount. Then, based on the target reduction amount, the command value of the torque current command is reduced to obtain the target torque current command, and the motor is controlled to run according to the target torque current command.

[0051] Therefore, when there is a risk of overcurrent in the frequency converter, this application appropriately reduces the torque current command value output by the frequency converter to the motor based on the current error. The adjusted torque current command effectively controls the three-phase current output of the motor within a relatively safe range, thereby avoiding overcurrent problems in the frequency converter and improving the safety and reliability of both the frequency converter and the motor.

[0052] The subject of the inverter overcurrent suppression method of this application can be a motor control system that includes an inverter and a motor, or an inverter or a device with inverter function, or other devices that include an inverter. This embodiment does not specifically limit this.

[0053] The inverter overcurrent suppression method of this application can be applied to fields such as air conditioning and automobiles, both of which rely on inverters for precise motor control to perform specific functions. In the air conditioning application, the inverter overcurrent suppression method of this application can be implemented simultaneously while the inverter adjusts the motor speed to achieve precise control of the air conditioner's cooling or heating capacity, thus suppressing the inverter's overcurrent. In the automotive application, since functions such as starting, acceleration, and high-speed driving all rely on inverters for precise motor control, the inverter overcurrent suppression method of this application can be implemented simultaneously in the automotive process where inverters are used to control the motor to achieve the corresponding functions, thereby suppressing the inverter's overcurrent.

[0054] The following description uses a motor control system as the main actuator to illustrate the various embodiments.

[0055] Based on this, this application proposes a first embodiment of an inverter overcurrent suppression method, please refer to... Figure 1 The inverter overcurrent suppression method includes steps S10 to S30:

[0056] Step S10: Obtain the effective value of the three-phase current of the motor controlled by the frequency converter and the difference between it and the preset current limit value to obtain the current error.

[0057] It should be noted that when converting the three-phase current signal into an equivalent DC current signal, the value of this DC current signal is the effective value of the three-phase current. The current limit value refers to an upper limit value of the current set during motor operation to protect the motor and its control system (such as the frequency converter) from damage. When the motor's operating current exceeds this limit value, the control system will take corresponding measures (such as reducing the output voltage, cutting off the power supply, etc.) to limit the current, ensuring that the motor operates within a safe current range. The current limit value can be flexibly set by the user according to the actual product parameters of the frequency converter, or it can be a default value; this embodiment does not specifically limit this.

[0058] Additionally, it should be noted that before executing step S10, the effective value of the three-phase current of the motor controlled by the frequency converter needs to be obtained first. To obtain the effective value of the three-phase current of the motor controlled by the frequency converter, the current values ​​of each of the three phases of the motor can be obtained first through current sensors; then, the sum of the average values ​​of each current value is calculated; finally, the square root of the calculated sum is taken to obtain the effective value of the three-phase current of the motor. The content of this part related to step S10 can be represented by the following formula:

[0059]

[0060] Where Is_err is the current error, Iu is the motor current value in phase u, Iv is the motor current value in phase v, Is is the motor current value in phase w, and Is_limit is the current limit value.

[0061] When obtaining the difference between the effective value of the three-phase current of the motor controlled by the frequency converter and the preset current limit value, it can be obtained in real time or periodically at certain time intervals. This embodiment does not specifically limit this. Generally, in order to better avoid the problem of overcurrent in the frequency converter, the real-time acquisition method is usually adopted.

[0062] Step S20: When the current error is greater than zero, determine the target reduction amount of the torque current command output by the frequency converter to the motor based on the current error; the current error is positively correlated with the target reduction amount.

[0063] It should be noted that the target reduction amount refers to the torque and current command that the frequency converter outputs to the motor at the current moment, and the magnitude of the command value that needs to be reduced. The current error is positively correlated with the target reduction amount; that is, the larger the current error, the larger the target reduction amount.

[0064] Understandably, the effective value of the motor's three-phase current is determined by the value of the torque current command. Specifically, the larger the absolute value of the torque current command, the larger the effective value of the motor's three-phase current. However, a larger effective value of the motor's three-phase current also results in a larger current error. Therefore, when reducing the torque current command value output by the frequency converter to the motor to prevent overcurrent problems, the required reduction in command value is also greater. Thus, to ensure a good overcurrent suppression effect, the current error must be positively correlated with the target reduction amount when suppressing overcurrent in the frequency converter.

[0065] In one possible implementation, step S20 may include step S21:

[0066] Step S21: Calculate the product of the current error and the preset command value reduction ratio to obtain the target reduction amount of the torque current command; the command value reduction ratio is greater than zero and less than or equal to the preset coefficient threshold.

[0067] It should be noted that the command value reduction ratio is a scaling factor used when determining the target reduction amount of the torque current command based on the current error. The command value reduction ratio can be flexibly set by the user according to the actual operating conditions of the motor, or it can be a default value; this embodiment does not impose specific limitations on it.

[0068] Additionally, it should be noted that to ensure the determined target reduction amount can correctly decrease the torque current command value without increasing it, the command value reduction ratio needs to be set to be greater than zero. Furthermore, to prevent motor vibration caused by excessive current adjustment, the command value reduction ratio needs to be set to be less than or equal to a preset threshold. Therefore, the command value reduction ratio needs to be greater than zero and less than or equal to the preset threshold. The preset threshold can be flexibly set by the user according to actual conditions, or it can be a default value; this embodiment does not specifically limit this. For example, the preset threshold can be set to 2.

[0069] Although the command value reduction ratio can be set to any value from 0 to a preset threshold, in actual use, when the motor control system uses the set command value reduction ratio to determine the target reduction amount, an inappropriate setting may result in the determined target reduction amount being too large or too small. A target reduction amount that is too large can easily cause motor vibration; a target reduction amount that is too small will result in poor overcurrent suppression. Therefore, to ensure a good overcurrent suppression effect without causing motor vibration, the optimal value between 0 and the preset threshold can be determined through debugging, and this value can be used as the final command value reduction ratio. This will optimally achieve the goal of "achieving a good overcurrent suppression effect without causing motor vibration."

[0070] In another feasible implementation, step S20 may include step S22:

[0071] Step S22: Using the current error as an index, find the reduction amount corresponding to the current error in the preset relationship table, and use it as the target reduction amount of the torque current command.

[0072] It should be noted that the relationship table is used to record different current errors and the reduction amount that has a mapping relationship with each current error. The relationship table can be a fixed table or a table that can be flexibly updated according to the actual situation; this embodiment does not impose a specific limitation on this.

[0073] In this embodiment, by pre-setting a table to record different current errors and a table showing the reduction amount that is mapped to each current error, the target reduction amount can be determined directly by looking up the table when needed, thus improving the efficiency of determining the target reduction amount.

[0074] It is understandable that, regarding the two feasible implementation methods of step S20 provided above, although the method using a relational table is more efficient, the amount of data that a relational table can record is limited. Therefore, it is only applicable to determining the target reduction amount for a portion of the current errors (i.e., the current errors recorded in the table). While the method of determining the target reduction amount through calculation is not as efficient as the relational table method, it is applicable to various current error situations, thus having a wider range of applications and ensuring the accuracy of the determined target reduction amount. Therefore, in practical use, users can flexibly choose the method for determining the target reduction amount according to their actual needs.

[0075] The above are only two feasible implementation methods of step S20 provided in this embodiment. This embodiment does not specifically limit the specific implementation method of step S20.

[0076] Step S30: Based on the target reduction amount, reduce the command value of the torque current command to obtain the target torque current command, and control the motor to run according to the target torque current command.

[0077] It should be noted that the target torque current command is the torque current command after reducing the command value.

[0078] In one feasible implementation, step S30 may include steps S31 to S32:

[0079] Step S31: If the command value of the torque current command is greater than zero, the command value of the torque current command is reduced by subtracting the command value of the torque current command from the target reduction amount to obtain the target torque current command.

[0080] It is understandable that if the torque current command value is greater than zero, it indicates that the torque current command is a positive current command, and the larger the positive current command value, the larger the motor current. Therefore, by subtracting the torque current command value from the target reduction amount, the torque current command value can be reduced to obtain the target torque current command.

[0081] Step S32: If the command value of the torque current command is less than zero, the command value of the torque current command is reduced by adding the command value of the torque current command to the target reduction amount, thereby obtaining the target torque current command.

[0082] Understandably, if the torque current command value is less than zero, it indicates a negative current command. A negative current command, with a larger value, results in a smaller motor current. Since the target reduction is greater than zero, the torque current command value needs to be added to the target reduction to decrease the torque current command value and obtain the target torque current command.

[0083] For example, the contents of steps S31 to S32 above can be represented by the following formula:

[0084] Iqcmd=Iqcmd0-Iqcmd_Adj*sign(Iqcmd0)

[0085] Where Iqcmd is the command value of the target torque current command, Iqcmd0 is the command value of the torque current command, Iqcmd_Adj is the target reduction amount, and sign(Iqcmd0) is used to characterize the positive or negative sign of the torque current command.

[0086] This embodiment provides an overcurrent suppression method for frequency converters. First, the effective value of the three-phase current of the motor controlled by the frequency converter is obtained, and the difference between it and the preset current limit value is used to obtain the current error. If the current error is greater than zero, it indicates that there is a risk of overcurrent in the frequency converter. Then, based on the current error, the target reduction amount of the torque current command output by the frequency converter to the motor can be determined. The current error is positively correlated with the target reduction amount. Then, based on the target reduction amount, the command value of the torque current command is reduced to obtain the target torque current command, and the motor is controlled to run according to the target torque current command.

[0087] Therefore, in this embodiment, when there is a risk of overcurrent in the frequency converter, the torque current command value output by the frequency converter to the motor will be appropriately reduced according to the current error. This adjusted torque current command effectively controls the three-phase current output of the motor within a relatively safe range, thereby avoiding overcurrent problems in the frequency converter and improving the safety and reliability of both the frequency converter and the motor.

[0088] Based on the first embodiment described above, a second embodiment of the inverter overcurrent suppression method of this application is proposed. In the second embodiment, step S30 may include steps S301 to S302:

[0089] Step S301: Limit the target reduction amount to obtain the target reduction amount after limiting.

[0090] It should be noted that the purpose of the limiting process is to ensure that the reduction in the target amount is not lower than a specific value (e.g., zero).

[0091] Step S302: Based on the target reduction amount after limiting, reduce the command value of the torque current command to obtain the target torque current command.

[0092] Understandably, if the target reduction amount of the torque current command is less than zero, it will actually increase the torque current command value, thereby increasing the risk of overcurrent in the inverter. Therefore, this embodiment limits the target reduction amount to ensure that the target reduction amount of the subsequent torque current command will not be less than zero. This ensures that when the motor operates according to the target torque current command, the three-phase current output of the motor can be effectively controlled within a relatively safe range, thus avoiding overcurrent problems in the inverter and improving the safety and reliability of both the inverter and the motor.

[0093] Based on the first and / or second embodiments described above, a third embodiment of the inverter overcurrent suppression method of this application is proposed. In the third embodiment, before step S30: reducing the command value of the torque current command according to the target reduction amount to obtain the target torque current command, steps S031 to S033 may be included:

[0094] Step S031: Determine whether the target reduction amount is greater than the preset reduction amount threshold;

[0095] It should be noted that the preset reduction threshold is the maximum value that can be reduced in a single torque current command, provided that the motor does not vibrate. The preset reduction threshold can be flexibly set by the user according to the actual situation, or it can be a default value. This embodiment does not impose specific limitations on it.

[0096] Step S032: If the target reduction amount is greater than the preset reduction amount threshold, reduce the command value of the torque current command according to the preset reduction amount threshold to obtain the target torque current command.

[0097] In one feasible implementation, if the target reduction amount is determined by multiplying the calculated current error by a preset command value reduction ratio, then after step S032, the command value reduction ratio can be further reduced to obtain a new command value reduction ratio. The system is then controlled to subsequently determine the target reduction amount according to the new command value reduction ratio.

[0098] Step S033: If the target reduction amount is less than or equal to the preset reduction amount threshold, execute the step of reducing the torque current command value according to the target reduction amount to obtain the target torque current command.

[0099] In this embodiment, a preset reduction threshold limits the maximum reduction value of the torque current command that can be applied in a single operation. Therefore, if the determined target reduction amount is greater than the preset reduction threshold, the torque current command value will be reduced according to the preset reduction threshold, not the target reduction amount, to obtain the target torque current command. This ensures that the change in motor current will not be excessive when the motor is controlled to run according to the target torque current command, avoiding motor vibration and improving the stability of motor operation. Conversely, if the determined target reduction amount is less than or equal to the preset reduction threshold, the torque current command value can be reduced normally according to the target reduction amount to obtain the target torque current command.

[0100] Based on the first, second, and / or third embodiments described above, a fourth embodiment of the inverter overcurrent suppression method of this application is proposed. In the fourth embodiment, before controlling the motor to run according to the target torque current command in step S30, steps S034 to S036 may be included:

[0101] Step S034: Determine whether the command value of the target torque current command is less than the preset command threshold.

[0102] It should be noted that the preset command threshold is the minimum command value that the torque current command must reach to ensure the normal operation of the motor.

[0103] Step S035: If the command value of the target torque current command is less than the preset command threshold, adjust the command value of the target torque current command to the preset command threshold, and control the motor to run according to the adjusted target torque current command.

[0104] Step S036: If the command value of the target torque current command is greater than or equal to the preset command threshold, execute the step of controlling the motor to run according to the target torque current command.

[0105] Understandably, if the torque current command used to control motor operation is too small, the torque generated by the motor will be insufficient to meet the load demand, leading to a decrease in speed and affecting the motor's efficiency. Furthermore, if the motor operates for an extended period with insufficient torque and decreased speed, it may generate excessive heat due to excessive friction of internal components and low energy conversion efficiency. Poor heat dissipation could lead to overheating or even damage to the motor. Therefore, this embodiment limits the minimum required torque current command value for controlling motor operation by setting a preset command threshold. Thus, if the target torque current command value is less than the preset command threshold, the target torque current command value must be adjusted to the preset command threshold before using it to control the motor, thereby ensuring normal motor operation. Conversely, if the target torque current command value is greater than or equal to the preset command threshold, it can be used directly to control the motor.

[0106] For example, to help understand the overall implementation flow of the inverter overcurrent suppression method obtained by combining the first and second embodiments described above, please refer to... Figure 2 and Figure 3 , specifically:

[0107] First, the effective value of the three-phase current of motor M is obtained through the current sensor. Then, the current error is obtained by subtracting the effective value of the three-phase current from the current limit value Is_Limit of the frequency converter. Next, the current error is multiplied by the reduction ratio coefficient Kp of the command value, and the result of the multiplication is limited to obtain the target reduction amount. After that, according to the target reduction amount, the command value of the torque current command is reduced to obtain the target torque current command, and the motor is controlled to run according to the target torque current command.

[0108] in, Figure 3 The content outside the dashed box, apart from obtaining the effective value of the three-phase current from the motor M, and after limiting, reducing the torque current command value according to the target reduction amount to obtain the target torque current command, and controlling the motor to run according to the target torque current command, is not part of the content required for the inverter overcurrent suppression method of this application, and therefore is not elaborated.

[0109] Furthermore, to aid in understanding the inverter overcurrent suppression method of this application, please refer to the following for the overcurrent suppression effect on the inverter. Figure 4 and Figure 5 Specifically, before overcurrent suppression, the motor current will appear as follows: Figure 4 The waveform shown indicates a maximum peak current of 92A, exceeding the inverter's maximum safe current, thus causing an overcurrent. After overcurrent suppression, the motor current will appear as follows: Figure 5 The waveform shown is such that the maximum peak current is 88A, which does not exceed the inverter's maximum safe current, thus preventing overcurrent in the inverter.

[0110] It should be noted that this example is only for the purpose of assisting in understanding this application and does not constitute a limitation on the inverter overcurrent suppression method of this application. Any simple modifications based on this technical concept are within the protection scope of this application.

[0111] This application also provides an overcurrent suppression device for a frequency converter. Please refer to... Figure 6 The inverter overcurrent suppression device includes:

[0112] The data acquisition module 10 is used to acquire the effective value of the three-phase current of the motor controlled by the frequency converter and the difference between it and the preset current limit value to obtain the current error.

[0113] Data processing module 20 is used to determine the target reduction amount of the torque current command output by the frequency converter to the motor based on the current error when the current error is greater than zero; the current error is positively correlated with the target reduction amount.

[0114] The overcurrent suppression module 30 is used to reduce the command value of the torque current command according to the target reduction amount, obtain the target torque current command, and control the motor to run according to the target torque current command.

[0115] Optionally, the data processing module 20 is also used for:

[0116] The target reduction amount of the torque current command is obtained by multiplying the current error by the preset reduction ratio of the command value; the reduction ratio of the command value is greater than zero and less than or equal to the preset coefficient threshold.

[0117] Optionally, the data processing module 20 is also used for:

[0118] Using the current error as an index, the corresponding reduction amount is found in a preset relationship table and used as the target reduction amount for the torque current command.

[0119] Optionally, the overcurrent suppression module 30 is also used for:

[0120] The reduction in the target is limited to obtain the reduced target amount.

[0121] Based on the target reduction amount after the amplitude limit, the command value of the torque current command is reduced to obtain the target torque current command.

[0122] Optionally, the overcurrent suppression module 30 is also used for:

[0123] Determine whether the target reduction amount is greater than the preset reduction amount threshold;

[0124] If the target reduction amount is greater than the preset reduction amount threshold, the torque current command value is reduced according to the preset reduction amount threshold to obtain the target torque current command.

[0125] If the target reduction amount is less than or equal to the preset reduction amount threshold, execute the step of reducing the torque current command value according to the target reduction amount to obtain the target torque current command.

[0126] Optionally, the overcurrent suppression module 30 is also used for:

[0127] Determine whether the command value of the target torque current command is less than the preset command threshold;

[0128] If the value of the target torque current command is less than the preset command threshold, the value of the target torque current command is adjusted to the preset command threshold, and the motor is controlled to run according to the adjusted target torque current command.

[0129] If the value of the target torque current command is greater than or equal to the preset command threshold, the step of controlling the motor to run according to the target torque current command is executed.

[0130] Optionally, the overcurrent suppression module 30 is also used for:

[0131] If the value of the torque current command is greater than zero, the value of the torque current command is reduced by subtracting the value of the torque current command from the target reduction amount, thus obtaining the target torque current command.

[0132] If the value of the torque current command is less than zero, the value of the torque current command is reduced by adding the value of the torque current command to the target reduction amount, thus obtaining the target torque current command.

[0133] The inverter overcurrent suppression device provided in this application embodiment can improve the safety and reliability of the inverter and motor. Compared with the prior art, the beneficial effects of the inverter overcurrent suppression device provided in this application embodiment are the same as the beneficial effects of the inverter overcurrent suppression method provided in the above embodiments, and will not be repeated here.

[0134] This application also provides a motor control system, please refer to... Figure 7 The motor control system includes a frequency converter 101 and a motor 102. The motor control system can be used to implement the steps of the frequency converter overcurrent suppression method in the above embodiments.

[0135] It should be noted that the motor 102 can be a permanent magnet synchronous motor, an asynchronous motor, etc., and this embodiment does not specifically limit it. Furthermore, Figure 7 The motor control system shown is merely an example and does not impose any limitation on the functionality and scope of use of the embodiments of this application.

[0136] The motor control system provided in this application embodiment can improve the safety and reliability of the frequency converter and the motor. Compared with the prior art, the beneficial effects of the motor control system provided in this application embodiment are the same as those of the frequency converter overcurrent suppression method provided in the above embodiments, and other technical features in this motor control system are the same as those disclosed in the methods of the above embodiments, and will not be repeated here.

[0137] The above description is merely a specific implementation of the embodiments of this application, but the protection scope of the embodiments of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the protection scope of the embodiments of this application. Therefore, the protection scope of the embodiments of this application should be determined by the protection scope of the above claims.

[0138] This application also provides a computer-readable storage medium storing a computer program that can run on a processor. The computer program is used to execute the inverter overcurrent suppression method in the above embodiments.

[0139] The computer-readable storage medium provided in this application embodiment may be, for example, a USB flash drive, but is not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or any combination thereof. More specific examples of computer-readable storage media may include, but are not limited to: electrical connections with one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In this embodiment, the computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, system, or device. The program code contained on the computer-readable storage medium may be transmitted using any suitable medium, including but not limited to: wires, optical cables, RF (Radio Frequency), etc., or any suitable combination thereof.

[0140] The aforementioned computer-readable storage medium may be included in the frequency converter or may exist independently and not assembled into the frequency converter.

[0141] The aforementioned computer-readable storage medium carries one or more programs. When the aforementioned one or more programs are executed by the frequency converter, the frequency converter: obtains the difference between the effective value of the three-phase current of the motor controlled by the frequency converter and the preset current limit value to obtain the current error; when the current error is greater than zero, determines the target reduction amount of the torque current command output by the frequency converter to the motor based on the current error; the current error is positively correlated with the target reduction amount; and reduces the command value of the torque current command based on the target reduction amount to obtain the target torque current command, and controls the motor to run according to the target torque current command.

[0142] Computer program code for performing the operations of this disclosure can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0143] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0144] The modules described in the embodiments of this application can be implemented in software or hardware. The names of the modules do not necessarily limit the functionality of the unit itself.

[0145] The computer-readable storage medium provided in this application embodiment stores computer-readable program instructions for executing the above-described inverter overcurrent suppression method, which can improve the safety and reliability of the inverter and the motor. Compared with the prior art, the beneficial effects of the computer-readable storage medium provided in this application embodiment are the same as the beneficial effects of the inverter overcurrent suppression method provided in the above embodiments, and will not be repeated here.

[0146] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the inverter overcurrent suppression method described above.

[0147] The computer program product provided in this application can improve the safety and reliability of frequency converters and motors. Compared with the prior art, the beneficial effects of the computer program product provided in this application are the same as those of the frequency converter overcurrent suppression method provided in the above embodiments, and will not be repeated here.

[0148] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent scope of this application.

Claims

1. A method for suppressing overcurrent in a frequency converter, characterized in that, The method includes: The difference between the effective value of the three-phase current of the motor controlled by the frequency converter and the preset current limit value is used to obtain the current error. When the current error is greater than zero, the target reduction amount of the torque current command output by the frequency converter to the motor is determined based on the current error; the current error is positively correlated with the target reduction amount. Based on the target reduction amount, the command value of the torque current command is reduced to obtain the target torque current command, and the motor is controlled to run according to the target torque current command.

2. The method as described in claim 1, characterized in that, The step of determining the target reduction amount of the torque current command output by the frequency converter to the motor based on the current error includes: The target reduction amount of the torque current command is obtained by multiplying the current error by a preset reduction ratio coefficient. The reduction ratio coefficient is greater than zero and less than or equal to a preset coefficient threshold.

3. The method as described in claim 1, characterized in that, The step of determining the target reduction amount of the torque current command output by the frequency converter to the motor based on the current error includes: Using the current error as an index, the reduction amount corresponding to the current error is found in a preset relationship table and used as the target reduction amount of the torque current command.

4. The method as described in claim 1, characterized in that, The step of reducing the command value of the torque current command according to the target reduction amount to obtain the target torque current command includes: The target reduction amount is limited to obtain the limited target reduction amount; Based on the target reduction amount after limiting, the command value of the torque current command is reduced to obtain the target torque current command.

5. The method according to any one of claims 1 to 4, characterized in that, Before the step of reducing the command value of the torque current command according to the target reduction amount to obtain the target torque current command, the method further includes: Determine whether the target reduction amount is greater than a preset reduction amount threshold; If the target reduction amount is greater than the preset reduction amount threshold, the command value of the torque current command is reduced according to the preset reduction amount threshold to obtain the target torque current command; If the target reduction amount is less than or equal to the preset reduction amount threshold, the step of reducing the torque current command value according to the target reduction amount to obtain the target torque current command is executed.

6. The method according to any one of claims 1 to 4, characterized in that, Before the step of controlling the motor to operate according to the target torque current command, the method further includes: Determine whether the command value of the target torque current command is less than a preset command threshold; If the command value of the target torque current command is less than the preset command threshold, the command value of the target torque current command is adjusted to the preset command threshold, and the motor is controlled to run according to the adjusted target torque current command. If the command value of the target torque current command is greater than or equal to the preset command threshold, the step of controlling the motor to run according to the target torque current command is executed.

7. The method according to any one of claims 1 to 4, characterized in that, The step of reducing the command value of the torque current command according to the target reduction amount to obtain the target torque current command includes: If the command value of the torque current command is greater than zero, the command value of the torque current command is reduced by subtracting the command value of the torque current command from the target reduction amount, thereby obtaining the target torque current command; If the command value of the torque current command is less than zero, the command value of the torque current command is reduced by adding the command value of the torque current command to the target reduction amount, thereby obtaining the target torque current command.

8. An overcurrent suppression device for a frequency converter, characterized in that, The device includes: The data acquisition module is used to acquire the effective value of the three-phase current of the motor controlled by the frequency converter and the difference between it and the preset current limit value to obtain the current error. The data processing module is used to determine, based on the current error, the target reduction amount of the torque current command output by the frequency converter to the motor when the current error is greater than zero; the current error is positively correlated with the target reduction amount. The overcurrent suppression module is used to reduce the command value of the torque current command according to the target reduction amount, obtain the target torque current command, and control the motor to run according to the target torque current command.

9. A motor control system, characterized in that, The motor control system includes a frequency converter and a motor, and the motor control system is used to implement the steps of the frequency converter overcurrent suppression method as described in any one of claims 1 to 7.

10. A storage medium, characterized in that, The storage medium is a computer-readable storage medium, and a computer program is stored on the computer-readable storage medium. When the computer program is executed by a processor, it implements the steps of the inverter overcurrent suppression method according to any one of claims 1 to 7.

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