Current imbalance suppression method, device and system and storage medium

Abstract

The invention discloses a current imbalance suppression method, device and system and a storage medium. The method comprises the following steps: acquiring a three-phase current output by a motor under a three-phase static coordinate system; converting the three-phase current into a two-phase current under a two-phase static coordinate system; based on a second-order generalized integral, two-phase current obtained after three-phase current conversion is extracted, and a negative-sequence current component of the two-phase current in a two-phase static coordinate system is obtained; obtaining a negative sequence voltage compensation amount based on the negative sequence current component; and superposing the negative-sequence voltage compensation quantity into the three-phase voltage modulation wave, and suppressing a negative-sequence current component in the three-phase current output by the motor. According to the method, the condition that the three-phase current of the motor is unbalanced can be improved, the operation stability and reliability of the motor are improved, and the service life of the motor is prolonged.

Description

Technical Field

[0001] The present application relates to the technical field of frequency converters, and in particular to a method, device, system and storage medium for suppressing current imbalance. Background Art

[0002] In the field of motor control, bus voltage fluctuations or other factors often lead to imbalance in the three-phase current of the motor. This imbalance not only affects the normal operation of the motor, but also causes the motor torque fluctuation to increase, and in severe cases may even cause the motor to fail. Summary of the invention

[0003] The present application provides a method, device, system and storage medium for suppressing current imbalance, which can improve the imbalance of three-phase current of a motor, improve the operating stability and reliability of the motor, and extend the service life of the motor.

[0004] In a first aspect, the present application provides a method for suppressing current imbalance, the method comprising:

[0005] Obtain the three-phase current of the motor output in the three-phase stationary coordinate system;

[0006] Converting the three-phase current into a two-phase current in a two-phase stationary coordinate system;

[0007] Based on the second-order generalized integral, the two-phase currents are extracted to obtain negative-sequence current components of the two-phase currents in a two-phase stationary coordinate system;

[0008] Based on the negative-sequence current component, a negative-sequence voltage compensation amount is obtained;

[0009] The negative-sequence voltage compensation amount is superimposed on the three-phase voltage modulation wave to suppress the negative-sequence current component in the three-phase current output by the motor.

[0010] A further technical solution is that the two-phase current is extracted based on the second-order generalized integral to obtain the negative sequence current component of the two-phase current in the two-phase stationary coordinate system, including:

[0011] Performing a second-order generalized integration on the two-phase currents to obtain two groups of orthogonal current signals;

[0012] Based on the two groups of orthogonal current signals, a negative sequence current component of the three-phase current in a two-phase stationary coordinate system is obtained.

[0013] A further technical solution is that the two-phase current includes a first-phase current and a second-phase current, the two-phase stationary coordinate system includes a first coordinate axis and a second coordinate axis that are perpendicular to each other, and the two-phase current is subjected to a second-order generalized integration to obtain two sets of orthogonal current signals, including:

[0014] Inputting the first phase current and the second phase current into a filter to obtain a first filtered current signal corresponding to the first phase current, a second filtered current signal corresponding to the second phase current, a first filtered quadrature current signal corresponding to the first phase current, and a second filtered quadrature current signal corresponding to the second phase current;

[0015] The first filtered current signal and the first filtered orthogonal current signal are a first group of orthogonal current signals under the first coordinate axis, and the second filtered current signal and the second filtered orthogonal current signal are a second group of orthogonal current signals under the second coordinate axis.

[0016] A further technical solution is that, based on the two groups of orthogonal current signals, the negative sequence current component of the three-phase current in a two-phase stationary coordinate system is obtained, including:

[0017] Obtaining a negative sequence current component of the three-phase current under the first coordinate axis based on the sum of the first filtered current signal and the second filtered quadrature signal;

[0018] Based on the difference between the second filtered current signal and the first filtered quadrature signal, a negative sequence current component of the three-phase current on the second coordinate axis is obtained.

[0019] A further technical solution is to obtain the negative sequence voltage compensation in a three-phase stationary coordinate system based on the negative sequence current component, including:

[0020] Convert the negative sequence current component into a negative sequence DC component;

[0021] Based on the negative sequence DC component, the negative sequence voltage compensation in the two-phase rotating coordinate system is obtained;

[0022] The negative sequence voltage compensation is subjected to an inverse Park transformation to obtain the negative sequence voltage compensation in a three-phase stationary coordinate system.

[0023] A further technical solution is to obtain the negative sequence voltage compensation in a two-phase rotating coordinate system based on the negative sequence DC component, including:

[0024] Get the proportional gain and integral gain of the PI controller;

[0025] Based on the proportional gain, the integral gain, the negative-sequence DC component and the integral operator, the negative-sequence voltage compensation amount in the two-phase rotating coordinate system is obtained, wherein the value of the negative-sequence DC component is controlled to 0 by using a PI controller.

[0026] A further technical solution is to transform the negative sequence current component into a negative sequence DC component, including:

[0027] Establish a coordinate system with the opposite direction of rotation to the voltage angle;

[0028] In a coordinate system with a rotation direction opposite to that of the voltage angle, the negative-sequence current component is transformed based on a preset motor rotor angle to obtain a negative-sequence DC component.

[0029] In a second aspect, the present application provides a current imbalance suppression device, the current imbalance suppression device comprising a unit for executing any one of the above methods.

[0030] In a third aspect, the present application provides a current imbalance suppression system, the current imbalance suppression system comprising a memory and a processor, the memory is used to store program data, and the processor is used to execute the program data to implement the steps of any of the above methods.

[0031] In a fourth aspect, the present application provides a computer-readable storage medium, which is used to store a computer program, and when the computer program is executed by a processor, it is used to implement the steps of any of the above methods.

[0032] The beneficial effect of the present application is as follows: different from the prior art, the present application adopts a second-order generalized integration method to extract the two-phase current obtained after the three-phase current transformation, and obtains the negative-sequence current component of the two-phase current in the two-phase stationary coordinate system, and uses the negative-sequence current component to obtain the negative-sequence voltage compensation amount, and superimposes the negative-sequence voltage compensation amount on the three-phase voltage modulation wave, which is equivalent to applying a voltage opposite to the negative-sequence current component, thereby suppressing the negative-sequence current component in the three-phase current, thereby effectively offsetting the influence of the negative-sequence magnetic field generated by the negative-sequence current component on the motor, reducing the vibration and noise problems caused by current imbalance during the operation of the motor, improving the operation stability and reliability of the motor, and extending the service life of the motor.

[0033] In addition, the second-order generalized integration method is used to extract the two-phase current obtained after the three-phase current transformation, which can accurately separate the negative-sequence component. The second-order generalized integration method has the characteristic of no delay when extracting the negative-sequence component, which means that even under rapidly changing working conditions, the negative-sequence current component can be accurately obtained in real time. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. Among them:

[0035] Figure 1It is a flow chart of the first embodiment of the current imbalance suppression method provided by the present application;

[0036] Figure 2 It is a block diagram of the unbalanced suppression principle in the current unbalanced suppression method provided by the present application;

[0037] Figure 3 It is a schematic diagram of the negative sequence component extraction principle in the current imbalance suppression method provided by the present application;

[0038] Figure 4 It is a second-order generalized integral principle diagram in the current imbalance suppression method provided by the present application;

[0039] Figure 5 It is a structural schematic diagram of an embodiment of a computer-readable storage medium provided by the present application. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. It will be understood that the specific embodiments described herein are only used to explain the present application, rather than to limit the present application. It should also be noted that, for ease of description, only some but not all structures related to the present application are shown in the drawings. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0041] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0042] In the field of motor control, bus voltage fluctuations or other factors often lead to imbalance in the three-phase current of the motor. This imbalance not only affects the normal operation of the motor, but also causes the motor torque fluctuation to increase, and in severe cases may even cause the motor to fail.

[0043] Especially in the application of high-voltage inverters, the bus voltage fluctuation is particularly significant, making the current imbalance phenomenon more obvious. As the load current increases, this imbalance phenomenon will become more serious. Severe current imbalance will not only cause severe vibration and noise in the motor, but may also cause motor overheating and other mechanical failures, ultimately causing failure shutdown.

[0044] Therefore, in order to solve the above technical problems, the present application provides a method for suppressing current imbalance. Please refer to the following embodiments for details.

[0045] See also Figure 1 , Figure 1 1 is a flow chart of a first embodiment of a method for suppressing current imbalance provided by the present application. The method comprises:

[0046] Step 110: Obtain the three-phase current output by the motor in the three-phase stationary coordinate system.

[0047] Among them, the motor driving algorithm can be used to output a three-phase voltage modulation wave, and the three-phase current output by the motor can be obtained based on the three-phase voltage modulation wave.

[0048] Step 120: transform the three-phase current into a two-phase current in a two-phase stationary coordinate system.

[0049] Step 130: extracting the two-phase currents based on the second-order generalized integral to obtain negative-sequence current components of the two-phase currents in a two-phase stationary coordinate system.

[0050] Step 140: Obtain a negative-sequence voltage compensation amount based on the negative-sequence current component.

[0051] Step 150: superimpose the negative sequence voltage compensation amount on the three-phase voltage modulation wave to suppress the negative sequence current component in the three-phase current output by the motor.

[0052] In this way, the two-phase current obtained after the three-phase current transformation is extracted by adopting the second-order generalized integration method, and the negative-sequence current component of the two-phase current in the two-phase stationary coordinate system is obtained. The negative-sequence current component is used to obtain the negative-sequence voltage compensation amount, and the negative-sequence voltage compensation amount is superimposed on the three-phase voltage modulation wave, which is equivalent to applying a voltage opposite to the negative-sequence current component, thereby suppressing the negative-sequence current component in the three-phase current, thereby effectively offsetting the influence of the negative-sequence magnetic field generated by the negative-sequence current component on the motor, reducing the vibration and noise problems caused by current imbalance during the operation of the motor, improving the operation stability and reliability of the motor, and extending the service life of the motor.

[0053] In addition, the second-order generalized integration method is used to extract the two-phase current obtained after the three-phase current transformation, which can accurately separate the negative-sequence component. The second-order generalized integration method has the characteristic of no delay when extracting the negative-sequence component, which means that even under rapidly changing working conditions, the negative-sequence current component can be accurately obtained in real time.

[0054] Refer to the second embodiment of the current imbalance suppression method provided in this application. The method includes:

[0055] Step 210: Obtain the three-phase current output by the motor in the three-phase stationary coordinate system.

[0056] Step 220: transform the three-phase current into a two-phase current in a two-phase stationary coordinate system.

[0057] Wherein, step 230 may adopt the following formula 1:

[0058]

[0059] Among them, i α and i β is the two-phase current in the two-phase orthogonal stationary coordinate system, i a 、i b and i c It is the three-phase current output by the motor.

[0060] Step 230: Perform a second-order generalized integration on the two-phase currents to obtain two sets of orthogonal current signals.

[0061] The two-phase current includes a first-phase current and a second-phase current, and the two-phase stationary coordinate system includes a first coordinate axis and a second coordinate axis that are perpendicular to each other. Step 230 may include the following steps:

[0062] Step 231: Input the first phase current and the second phase current into a filter to obtain a first filtered current signal corresponding to the first phase current, a second filtered current signal corresponding to the second phase current, a first filtered quadrature current signal corresponding to the first phase current, and a second filtered quadrature current signal corresponding to the second phase current.

[0063] The first filtered current signal and the first filtered orthogonal current signal are a first group of orthogonal current signals under the first coordinate axis, and the second filtered current signal and the second filtered orthogonal current signal are a second group of orthogonal current signals under the second coordinate axis.

[0064] Specifically, step 231 may adopt the following formula 2 and formula 3:

[0065]

[0066] Among them, the filter includes a low-pass filter and a band-pass filter, k is the proportional coefficient between the low-pass filter and the band-pass filter, that is, the preset filter proportional coefficient, k can determine the bandwidth of the band-pass filter, ω is the angular frequency of the input current signal, and s is the integral operator.

[0067] The first phase current i α Substituting into formula 2, we get the first filtered current signal i α , the second phase current i βSubstituting into formula 2, we get the second filtered current signal i′ β .

[0068] The first phase current i α Substituting into formula 3, we get the first filtered quadrature current signal qi′ α , the second phase current i β Substituting into formula 3, we get the second filtered quadrature current signal qi′ β Among them, the first coordinate axis is the α axis, the second coordinate axis is the β axis, and the first filtered current signal i′ α The first filtered quadrature current signal qi′ α is the first set of orthogonal current signals, and the second filtered current signal i′ β The second filtered quadrature current signal qi′ β is the second set of orthogonal current signals.

[0069] Step 240: Based on the two groups of orthogonal current signals, obtain the negative sequence current component of the three-phase current in a two-phase stationary coordinate system.

[0070] Step 250: Obtain a negative-sequence voltage compensation amount based on the negative-sequence current component.

[0071] Step 260: superimpose the negative-sequence voltage compensation amount onto the three-phase voltage modulation wave to suppress the negative-sequence current component in the three-phase current output by the motor.

[0072] In some embodiments, step 240 may include the following:

[0073] Step 241: Based on the sum of the first filtered current signal and the second filtered quadrature signal, obtain the negative sequence current component of the three-phase current on the first coordinate axis.

[0074] Step 242: Based on the difference between the second filtered current signal and the first filtered quadrature signal, obtain the negative sequence current component of the three-phase current on the second coordinate axis.

[0075] For step 241 and step 242, the following formula 4 may be referred to:

[0076]

[0077] Among them, q is an orthogonal operator, and It is the negative sequence current component of the three-phase current in the two-phase stationary coordinate system.

[0078] Refer to the third embodiment of the current imbalance suppression method provided in the present application. The method includes:

[0079] Step 310: Obtain the three-phase current output by the motor in the three-phase stationary coordinate system.

[0080] Step 320: transform the three-phase current into a two-phase current in a two-phase stationary coordinate system.

[0081] Step 330: Based on the second-order generalized integral, the two-phase currents are extracted to obtain negative-sequence current components of the two-phase currents in a two-phase stationary coordinate system.

[0082] Step 340: transform the negative sequence current component into a negative sequence DC component.

[0083] Wherein, step 340 may include the following steps:

[0084] Step 341: Establish a coordinate system with a rotation direction opposite to the voltage angle.

[0085] Step 342: In a coordinate system with a rotation direction opposite to that of the voltage angle, based on a preset motor rotor angle, the negative-sequence current component is transformed to obtain a negative-sequence DC component.

[0086] Wherein, step 342 may adopt the following formula 5:

[0087]

[0088] Where, θ is the preset motor rotor angle, and It is the DQ-axis DC component of the negative-sequence component of the three-phase current in the negative-sequence rotating coordinate system, that is, the negative-sequence DC component.

[0089] Step 350: Based on the negative-sequence DC component, obtain a negative-sequence voltage compensation amount in a two-phase rotating coordinate system.

[0090] Wherein, step 350 may include the following steps:

[0091] Step 351: Obtain the proportional gain and integral gain of the PI controller.

[0092] Step 352: Based on the proportional gain, the integral gain, the negative-sequence DC component and the integral operator, a negative-sequence voltage compensation amount in the two-phase rotating coordinate system is obtained.

[0093] Wherein, step 351 and step 352 may adopt the following formula 6:

[0094]

[0095] Among them, k p and k i are the proportional gain and integral gain of the PI controller respectively, s is the integral operator, and They are respectively the negative-sequence compensation of DQ axis voltage in the negative-sequence DQ coordinate system.

[0096] Among them, the negative sequence DC component can be converted to and The value of is controlled to 0.

[0097] Step 360: Perform an inverse Park transformation on the negative sequence voltage compensation amount to obtain the negative sequence voltage compensation amount in the three-phase stationary coordinate system.

[0098] Wherein, step 360 may adopt the following formula 7:

[0099]

[0100] in, and They are respectively the negative sequence compensation of phases a, b and c in the three-phase stationary coordinate system.

[0101] Step 370: Superimpose the negative sequence voltage compensation amount on the three-phase voltage modulation wave to suppress the negative sequence current component in the three-phase current output by the motor.

[0102] Among them, step 310, step 320 and step 330 have the same or similar technical solutions as the above embodiment, and are not described in detail here.

[0103] Based on the above embodiments, combined with Figure 2 ,(in, Figure 2 In the embodiment, link 1 is a controller, link 2 is a PWM modulator, link 3 is a converter, link 4 is a motor, link 5 is a negative sequence extraction link, link 6 is a negative sequence Park conversion link, link 7 is a PI controller link, and link 8 is a negative sequence inverse Park conversion link). The current imbalance suppression method provided by the present application mainly includes the following steps:

[0104] S1: Get three-phase voltage u a 、u b and u c ;

[0105] S2: Use PWM modulator to adjust the three-phase voltage u according to the motor drive algorithm a 、u b and u c Modulate to obtain a three-phase voltage modulation wave;

[0106] S3: Get the three-phase current i output by the motor based on the three-phase voltage modulation wave a 、i b and i c ;

[0107] S4: transforming the three-phase current into a two-phase current in a two-phase stationary coordinate system;

[0108] S5: Based on the second-order generalized integral, the two-phase current obtained after the three-phase current transformation is extracted to obtain the negative sequence current component and

[0109] S6: Negative sequence current component and Transformed into negative sequence DC component and

[0110] S7: Based on negative sequence DC component and The PI controller is used to control the negative sequence DC component to 0, and the negative sequence voltage compensation in the two-phase rotating coordinate system is obtained. and

[0111] S8: Negative sequence voltage compensation and Perform inverse Park transformation to obtain the negative sequence voltage compensation in the three-phase stationary coordinate system and

[0112] S9: The negative sequence voltage compensation value in the three-phase stationary coordinate system and Superimposed on the three-phase voltage u a 、u b and u c middle.

[0113] See also Figure 3 and Figure 4 , the above S4 and S5 can be Figure 3 As shown, Figure 3 The link 1 is the Clark transformation link, the link 2 is the second-order generalized integration link, and the link 3 is the symmetric component conversion link. Specifically, the following steps may be included:

[0114] S51: Three-phase current i output to the motor a 、i b and i c Perform Clark transformation to obtain the two-phase current i in the two-phase orthogonal stationary coordinate system α and i β ;

[0115] S52: for two-phase current i α and i β Perform the second-order generalized integration respectively to obtain two sets of orthogonal current signals i′ α and qi′ α, i′ β and qi′ β ;

[0116] S53: Use the symmetrical component conversion matrix to calculate two sets of orthogonal current signals to obtain the negative sequence current components of the two-phase currents in the two-phase stationary coordinate system and

[0117] According to the symmetrical component theory, the asymmetric three-phase current in the motor can be decomposed into a symmetrical positive-sequence current component, a symmetrical negative-sequence current component and a zero-sequence current component. The imbalance problem of the three-phase current in the motor is mainly caused by the large negative-sequence current component. If the negative-sequence current component can be accurately extracted and then closed-loop suppressed, the motor current imbalance can be suppressed. Therefore, the present application adopts a second-order generalized integration method to extract the positive-sequence current component and the negative-sequence current component in the two-phase current respectively, and after obtaining the negative-sequence current component, a negative-sequence coordinate transformation is performed on it to obtain the negative-sequence DC component in the negative-sequence rotating coordinate system, and a PI controller is used to obtain the negative-sequence voltage compensation (i.e., the negative-sequence voltage compensation in the two-phase rotating coordinate system), and then the negative-sequence inverse coordinate transformation is performed to obtain the negative-sequence voltage compensation on the three-phase voltage modulation wave (i.e., the negative-sequence voltage compensation in the three-phase stationary coordinate system), and the negative-sequence voltage compensation is superimposed on the three-phase voltage modulation wave to suppress the negative-sequence current component in the three-phase current output by the motor.

[0118] Therefore, the present application adopts the second-order generalized integration method to extract the two-phase current obtained after the three-phase current transformation, and obtains the negative-sequence current component of the two-phase current in the two-phase stationary coordinate system, and uses the negative-sequence current component to obtain the negative-sequence voltage compensation amount, and superimposes the negative-sequence voltage compensation amount on the three-phase voltage modulation wave, which is equivalent to applying a voltage opposite to the negative-sequence current component, thereby suppressing the negative-sequence current component in the three-phase current, thereby effectively offsetting the influence of the negative-sequence magnetic field generated by the negative-sequence current component on the motor, reducing the vibration and noise problems caused by current imbalance during the operation of the motor, improving the operation stability and reliability of the motor, and extending the service life of the motor.

[0119] In addition, the second-order generalized integration method is used to extract the two-phase current obtained after the three-phase current transformation, which can accurately separate the negative-sequence component. The second-order generalized integration method has the characteristic of no delay when extracting the negative-sequence component, which means that even under rapidly changing working conditions, the negative-sequence current component can be accurately obtained in real time.

[0120] Corresponding to the current imbalance suppression method of the above embodiment, the present application also provides a current imbalance suppression device, which includes a unit for implementing the technical solution of any embodiment in the present application.

[0121] The present application also provides a current imbalance suppression system, which includes a memory and a processor, wherein a computer program is stored in the memory; and the processor is used to implement the current imbalance suppression method provided by any one of the aforementioned method embodiments when executing the computer program.

[0122] See also Figure 5 , Figure 5 The structure of an embodiment of a computer-readable storage medium provided by the present application is shown in FIG. 7 . The computer-readable storage medium 70 is used to store a computer program 71. When the computer program 71 is executed by a processor, it is used to implement the following method steps:

[0123] Obtain the three-phase current of the motor output in the three-phase stationary coordinate system;

[0124] Converting the three-phase current into a two-phase current in a two-phase stationary coordinate system;

[0125] Based on the second-order generalized integral, the two-phase currents are extracted to obtain negative-sequence current components of the two-phase currents in a two-phase stationary coordinate system;

[0126] Based on the negative-sequence current component, a negative-sequence voltage compensation amount is obtained;

[0127] The negative-sequence voltage compensation amount is superimposed on the three-phase voltage modulation wave to suppress the negative-sequence current component in the three-phase current output by the motor.

[0128] It can be understood that when the computer program 71 is executed by the processor, it is also used to implement the technical solution of any embodiment of the present application.

[0129] In the several embodiments provided in this application, it should be understood that the disclosed methods and devices can be implemented in other ways. For example, the device implementation described above is only illustrative, for example, the division of modules or units is only a logical function division, and there may be other division methods in actual implementation, such as two units or components can be combined or integrated into another system, or some features can be ignored or not executed.

[0130] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on two network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0131] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0132] If the integrated units in the above other embodiments are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, server, or network device, etc.) or a processor (processor) to perform all or part of the steps of each implementation method of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program code.

[0133] The above are only implementation methods of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for suppressing current imbalance, characterized in that the method include: Obtain the three-phase current of the motor output in the three-phase stationary coordinate system; Converting the three-phase current into a two-phase current in a two-phase stationary coordinate system; Based on the second-order generalized integral, the two-phase currents are extracted to obtain negative-sequence current components of the two-phase currents in a two-phase stationary coordinate system; Based on the negative-sequence current component, a negative-sequence voltage compensation amount is obtained; The negative-sequence voltage compensation amount is superimposed on the three-phase voltage modulation wave to suppress the negative-sequence current component in the three-phase current output by the motor.

2. The method for suppressing current imbalance according to claim 1, characterized in that: The two-phase currents are extracted based on the second-order generalized integral to obtain the negative sequence current components of the two-phase currents in a two-phase stationary coordinate system, including: Performing a second-order generalized integration on the two-phase currents to obtain two groups of orthogonal current signals; Based on the two groups of orthogonal current signals, a negative sequence current component of the three-phase current in a two-phase stationary coordinate system is obtained.

3. The method for suppressing current imbalance according to claim 2, characterized in that: The two-phase current includes a first-phase current and a second-phase current, the two-phase stationary coordinate system includes a first coordinate axis and a second coordinate axis that are perpendicular to each other, and the second-order generalized integration of the two-phase current is performed to obtain two sets of orthogonal current signals, including: Inputting the first phase current and the second phase current into a filter to obtain a first filtered current signal corresponding to the first phase current, a second filtered current signal corresponding to the second phase current, a first filtered quadrature current signal corresponding to the first phase current, and a second filtered quadrature current signal corresponding to the second phase current; The first filtered current signal and the first filtered orthogonal current signal are a first group of orthogonal current signals under the first coordinate axis, and the second filtered current signal and the second filtered orthogonal current signal are a second group of orthogonal current signals under the second coordinate axis.

4. The method for suppressing current imbalance according to claim 3, characterized in that: The method of obtaining the negative sequence current component of the three-phase current in a two-phase stationary coordinate system based on the two groups of orthogonal current signals includes: Obtaining a negative sequence current component of the three-phase current under the first coordinate axis based on the sum of the first filtered current signal and the second filtered quadrature signal; Based on the difference between the second filtered current signal and the first filtered quadrature signal, a negative sequence current component of the three-phase current on the second coordinate axis is obtained.

5. The method for suppressing current imbalance according to claim 1, characterized in that: The step of obtaining a negative-sequence voltage compensation amount in a three-phase stationary coordinate system based on the negative-sequence current component includes: Converting the negative-sequence current component into a negative-sequence DC component; Based on the negative-sequence DC component, a negative-sequence voltage compensation amount in a two-phase rotating coordinate system is obtained; The negative sequence voltage compensation amount is subjected to an inverse Park transformation to obtain a negative sequence voltage compensation amount in a three-phase stationary coordinate system.

6. The method for suppressing current imbalance according to claim 5, characterized in that: The step of obtaining a negative-sequence voltage compensation amount in a two-phase rotating coordinate system based on the negative-sequence DC component includes: Get the proportional gain and integral gain of the PI controller; Based on the proportional gain, the integral gain, and the negative-sequence DC component, a negative-sequence voltage compensation amount in a two-phase rotating coordinate system is obtained, wherein the value of the negative-sequence DC component is controlled to be 0 by using the PI controller.

7. The method for suppressing current imbalance according to claim 5, characterized in that: The step of converting the negative sequence current component into a negative sequence DC component comprises: Establish a coordinate system with the opposite direction of rotation to the voltage angle; In a coordinate system with a rotation direction opposite to that of the voltage angle, based on a preset motor rotor angle, the negative-sequence current component is transformed to obtain a negative-sequence DC component.

8. A current imbalance suppression device, characterized in that: The current unbalance suppression device comprises a unit for executing the method according to any one of claims 1-7.

9. A current unbalance suppression system, characterized in that: The current unbalance suppression system comprises a memory and a processor, wherein the memory is used to store program data, and the processor is used to execute the program data to implement the current unbalance suppression method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores program data, and when the program data is executed by a processor, it is used to implement the current imbalance suppression method according to any one of claims 1 to 7.

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