Inverter open circuit diagnostic method, system, and apparatus based on current dynamic reference

Abstract

The present application relates to the technical field of circuit fault diagnosis, and particularly relates to an inverter open circuit diagnosis method, system and device based on current dynamic scaling. The method comprises the following steps: collecting three-phase stator currents of a three-phase inverter drive system in real time, constructing current characteristic information, and obtaining three-phase stator currents after scaling processing; integrating the three-phase stator currents after scaling processing to obtain positive bias of phase current and negative bias of phase current; setting a judgment threshold, and converting the positive bias of phase current and the negative bias of phase current into current bias state parameters; calculating a fault identification variable according to the dynamic scaling current bias state parameters; matching the fault identification variable with a fault diagnosis judgment rule to locate a specific switch tube position where an open circuit fault occurs. The present application uses the idea of dynamic scaling, overcomes the interference of control factor uncertainty on the diagnosis criterion, completes online fault diagnosis, and provides a solid basis for fault-tolerant control and safety protection of the drive system.

Description

Technical Field

[0001] This invention relates to the field of circuit fault diagnosis technology, and in particular to an inverter open-circuit diagnosis method, system and device based on dynamic per-unit current. Background Technology

[0002] In real-world applications, an open-circuit fault in a single power device can trigger a redistribution of power within the system. This sudden change can easily lead to overcurrent or overvoltage in another device connected in parallel or on the same bridge arm, thus inducing a secondary fault. If existing diagnostic strategies only address single-device faults, the entire system can rapidly escalate into a severe failure within milliseconds. This necessitates fault diagnosis algorithms capable of accurately locating both fault points, providing a reliable basis for further fault-tolerant control or safe shutdown actions, and preventing complete equipment loss of control.

[0003] To address these needs, existing fault diagnosis methods are mainly categorized into analytical model methods, data-driven methods, and signal processing methods. Current signal processing-based methods have attracted significant attention due to their advantage of intuitively reflecting the inverter's operating status and eliminating the need for additional signal detection equipment. The core of these methods lies in accurately identifying the stator current distortion process under specific fault conditions and extracting fault features with distinct differences. However, the current distortion process is heavily influenced by the adjustment of system control parameters, and these variable parameters directly lead to uncertainty in the fault current trajectory.

[0004] Most conventional fault current models currently lack parameters characterizing the controller's regulatory effect. This theoretical model deficiency severely limits the accuracy of algorithms, making it difficult to guarantee the generalization accuracy of diagnostic thresholds tuned based on conventional models under different operating conditions. Especially in the case of open-circuit faults in two transistors, the interaction between the faulty devices and the dynamic regulation of the controller are intertwined and coupled, making it extremely difficult to accurately describe the current behavior characteristics and evolution patterns under this complex state. Overcoming the uncertainty of control parameters and establishing a highly generalizable diagnostic criterion for open-circuit faults in two transistors has become a critical challenge in the current technological field. Summary of the Invention

[0005] This invention aims to at least solve one of the technical problems existing in related technologies. To this end, this invention provides an inverter open-circuit diagnosis method, system, and device based on dynamic per-unit current, which effectively overcomes the interference of control factor uncertainty on diagnostic criteria, completes online fault diagnosis, and provides a solid basis for fault-tolerant control and safety protection of drive systems.

[0006] This invention provides an inverter open-circuit diagnosis method based on dynamic current per-unit scaling, comprising: S1: Real-time acquisition of the three-phase stator current of the three-phase inverter drive system, construction of current characteristic information using natural constant, and obtaining the per-unit processed three-phase stator current; S2: The positive bias and negative bias of the phase current are calculated by integrating the normalized three-phase stator current. S3: Set the judgment threshold to convert the positive bias and the negative bias of the phase current into dynamically standardized current bias state parameters. S4: Calculate the fault identification variable based on the dynamically standardized current bias state parameters; S5: Based on the fault identifier variable, match the fault diagnosis and judgment rules to locate the specific switch where the open circuit fault occurred.

[0007] According to the inverter open-circuit diagnosis method based on dynamic current per unit provided by the present invention, the calculation formula for step S1 is as follows: in, This refers to the three-phase stator current after per-unit processing. For three-phase stator current, These are the per-unit parameters.

[0008] According to the inverter open-circuit diagnosis method based on dynamic current per unit provided by the present invention, the calculation formula for step S2 is as follows: in, This is a positive bias. It is a negative bias. This refers to the three-phase stator current after per-unit processing. It is an electrical angle.

[0009] According to the present invention, an inverter open-circuit diagnosis method based on dynamic per-unit current is provided, wherein step S3 is as follows: the current bias state parameters include positive bias state parameters and negative bias state parameters. When the positive bias is greater than or equal to a preset threshold, the positive bias state parameter is 1; when the negative bias is less than or equal to a preset threshold, the negative bias state parameter is -1; and the remaining current bias state parameters are all 0.

[0010] According to the present invention, an inverter open-circuit diagnosis method based on dynamic current per unit is provided, wherein the preset threshold is greater than 0 and less than 5 / 12.

[0011] According to the inverter open-circuit diagnosis method based on dynamic current per unit provided by the present invention, the calculation formula for step S4 is as follows: in, For the fault indicator variable indicating loss, For specific fault location, fault identifier variables, It is the sum of the absolute values ​​of the positive and negative biases of the first phase. It is the sum of the absolute values ​​of the positive and negative biases of the second phase. It is the sum of the absolute values ​​of the positive and negative biases of the third phase. This is the sum of the positive and negative bias degrees of the first phase. This is the sum of the positive and negative bias degrees of the second phase. It is the sum of the positive and negative biases of the third phase.

[0012] According to the inverter open-circuit diagnosis method based on dynamic current per unit provided by the present invention, the fault diagnosis judgment rule in step S5 is as follows: when D =1 ，r When =-1, S a1 Error; when D =1 ，r When =1, S a2 mistake; when D =1 ，r When =-2, S b1 Error; when D =1 ，r When =2, S b2 mistake; when D =1 ，r When =-4, S c1 Error; when D =1 ，r When =4, S c2 mistake; when D =3 ，r When =1, S a1 and S b1 Error; when D =2 ，r When =1, S a1 and S b2 mistake; when D =3 ，r When =-1, S a2 and S b2 Error; when D =2 ，r When =-1, S a2 and S b1 mistake; when D =3 ，r When =3, S a2 and S c2 Error; when D =2，r When =2, S b1 and S c2 mistake; when D =3 ，r When =-3, S a1 and S c1 Error; when D =2 ，r When =-2, S b2 and S c1 mistake; when D =3 ，r When =5, S b2 and S c2 Error; when D =2 ，r When =3, S a1 and S c2 mistake; when D =3 ，r When =-5, S b1 and S c1 Error; when D =2 ，r When =-3, S a2 and S c1 mistake; when D =0 ，r When =0, everything is normal; Among them, S a1 For the first phase upper tube, S a2 For the first phase lower tube, S b1 For the second phase upper tube, S b2 For the second phase lower tube, S c1 For the third phase upper tube, S c2 This is the lower tube of the third phase.

[0013] According to the present invention, an inverter open-circuit diagnostic method based on dynamic per-unit current is provided. This method is applicable to a dual-inverter architecture system, wherein one inverter is connected to a photovoltaic power generation unit and the other inverter is connected to a battery energy storage unit. This method achieves cross-topology power device open-circuit protection by monitoring the current bias state of the AC side of the two inverters.

[0014] This invention also provides an inverter open-circuit diagnostic system based on dynamic current per unit, comprising the following modules: Current acquisition module: used to acquire the three-phase stator current of the three-phase inverter drive system in real time, construct current characteristic information using natural constant, and obtain the three-phase stator current after per-unit processing; Offset Calculation Module: Used to integrate the normalized three-phase stator current to calculate the positive and negative offset of the phase current. State parameter calculation module: used to set the judgment threshold and convert the positive bias and the negative bias of the phase current into dynamic per-unit current bias state parameters. Fault Variable Calculation Module: Used to calculate fault identification variables based on dynamically standardized current bias state parameters; Fault diagnosis module: Used to locate the specific switch where an open circuit fault occurs by matching the fault identifier variable with the fault diagnosis and judgment rules.

[0015] The present invention also provides an electronic device, including a processor, a communication interface, a memory, and a communication bus, wherein the processor is used to execute a computer program to implement the steps of the inverter open-circuit diagnosis method based on current dynamic per-unit as described above.

[0016] The present invention provides an inverter open-circuit diagnosis method, system, and device based on dynamic current per unit, which has at least the following technical effects: 1. By utilizing the concepts of limit approximation and external equivalence, a unified modeling of the multiple possible behavioral characteristics of a dual-tube open-circuit fault under uncertain control parameters was achieved.

[0017] 2. By extracting the current bias characteristics, the influence of control parameter disturbances and acceleration / deceleration operating conditions on the generalization ability of diagnostic criteria is eliminated.

[0018] 3. This diagnostic criterion does not rely on establishing an accurate circuit model, and it can make up for the lack of flexibility of conventional signal processing methods when facing disturbance factors.

[0019] 4. This method can intuitively reflect the operating status of the inverter, and does not require additional large signal detection equipment.

[0020] 5. The algorithm has the ability to accurately locate two fault points, providing a reliable basis for the system to take further fault-tolerant control or safe shutdown, thus avoiding complete loss of control of the entire drive system.

[0021] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 This is a flowchart illustrating the inverter open-circuit diagnosis method based on dynamic current per unit provided by the present invention.

[0024] Figure 2 This is the equivalent circuit diagram of a three-phase voltage source inverter driving motor system.

[0025] Figure 3 For S a1 and S b1 Per-unit three-phase current diagram for handling open-circuit faults.

[0026] Figure 4 For power devices S a1 and S b1 The experimental results of simultaneous open-circuit faults are shown in the figure.

[0027] Figure 4 In the middle (a), the power device S is shown. a1 and S b1 Three-phase current diagrams showing simultaneous open-circuit faults.

[0028] Figure 4 (b) represents the power device S. a1 and S b1 Simultaneously, the first phase stator current diagram after per-unit processing for open-circuit faults.

[0029] Figure 4 (c) represents the power device S. a1 and S b1 Simultaneously, the per-unit processing of the second-phase stator current diagram after an open-circuit fault occurs.

[0030] Figure 4 In the middle (d), S represents the power device. a1 and S b1 The third-phase stator current diagram after per-unit processing for simultaneous open-circuit faults.

[0031] Figure 4 In the middle (e), S represents the power device. a1 and S b1 Simultaneous loss of open circuit faults, fault identifier variable diagram.

[0032] Figure 4 In the middle (f), S represents the power device. a1 and S b1 Simultaneously, the specific fault location and fault identification variable diagram of the open circuit fault occurred.

[0033] Figure 5 For power devices S a1 and S b2 The experimental results of an open-circuit fault occurred.

[0034] Figure 5 In the middle (a), the power device S is shown. a1 and S b2 Three-phase current diagram showing simultaneous open-circuit faults.

[0035] Figure 5 (b) represents the power device S. a1 and S b2 Simultaneously, the first phase stator current diagram after per-unit processing for open-circuit faults.

[0036] Figure 5 (c) represents the power device S. a1 and S b2 Simultaneously, the per-unit processing of the second-phase stator current diagram after an open-circuit fault occurs.

[0037] Figure 5 In the middle (d), S represents the power device. a1 and S b2 The third-phase stator current diagram after per-unit processing for simultaneous open-circuit faults.

[0038] Figure 5 In the middle (e), S represents the power device. a1 and S b2 Simultaneous loss of open circuit faults, fault identifier variable diagram.

[0039] Figure 5 In the middle (f), S represents the power device. a1 and S b2 Simultaneously, the specific fault location and fault identification variable diagram of the open circuit fault occurred.

[0040] Figure 6 This is a schematic diagram of the inverter open-circuit diagnostic system based on dynamic current per unit provided by the present invention.

[0041] Figure 7 This is a schematic diagram of the structure of the electronic device provided by the present invention.

[0042] Figure label: 101. Current acquisition module; 102. Bias calculation module; 103. Status parameter calculation module; 104. Fault variable calculation module; 105. Fault judgment module; 810. Processor; 820. Communication interface; 830. Memory; 840. Communication bus. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. The following embodiments are used to illustrate this invention but cannot be used to limit the scope of this invention.

[0044] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0045] The following is combined with Figures 1 to 7 This invention is described.

[0046] Example like Figure 1 As shown, Figure 1 This is a flowchart illustrating the inverter open-circuit diagnosis method based on dynamic current per-unit measurement provided by the present invention, including: S1: Real-time acquisition of the three-phase stator current of the three-phase inverter drive system, construction of current characteristic information using natural constant, and obtaining the per-unit processed three-phase stator current; S2: The positive bias and negative bias of the phase current are calculated by integrating the normalized three-phase stator current. S3: Set the judgment threshold to convert the positive bias and the negative bias of the phase current into dynamically standardized current bias state parameters. S4: Calculate the fault identification variable based on the dynamically standardized current bias state parameters; S5: Based on the fault identifier variable, match the fault diagnosis and judgment rules to locate the specific switch where the open circuit fault occurred.

[0047] like Figure 2 As shown, Figure 2 The equivalent circuit of a three-phase voltage source inverter driving a motor system is shown. Among them, S... a1 For the first phase upper tube, S a2 For the first phase lower tube, S b1For the second phase upper tube, S b2 For the second phase lower tube, S c1 For the third phase upper tube, S c2 This is the lower tube of the third phase.

[0048] Specifically, in step S1, the system needs to acquire and reconstruct the three-phase stator current signal of the drive system in real time. For a standard three-phase voltage source inverter driving motor equivalent circuit, its topology includes three-phase upper and lower bridge arm power devices. Under healthy operating conditions, it is assumed that the initial phase of the first phase current is 0 and its amplitude is... The theoretical model of sinusoidal three-phase current can be explicitly expressed as: in, It is a three-phase current. The initial phase of the three phases, It is the phase angle. Including the first phase current Second phase current Third phase current .

[0049] In harsh environments commonly encountered in industrial settings, such as severe temperature differences, high-frequency mechanical vibrations, and strong electromagnetic interference, traditional redundant multi-sensor detection schemes are prone to synchronization errors due to inconsistent component temperature drift or crosstalk between signal channels. The probability of single-point hardware failure also increases significantly with the number of sensors. To improve the robustness of detection at the physical level, this system implementation uses a single current sensor to collect critical circuit state information. This minimalist hardware topology completely eliminates the risk of cross-coupling when multiple sensors work together. By precisely sampling the DC bus current within the PWM carrier cycle and combining it with the inverter switching state, a high-fidelity three-phase stator AC current can be accurately reconstructed. The reconstructed stator current undergoes noise reduction filtering and is normalized based on the current amplitude under healthy conditions, thus providing a clean and dimensionless data source for subsequent feature diagnosis.

[0050] Specifically, the calculation formula for step S1 is as follows: in, This refers to the three-phase stator current after per-unit processing. For three-phase stator current, These are the per-unit parameters.

[0051] Specifically, the calculation formula for step S2 is as follows: in, This is a positive bias. It is a negative bias. This refers to the three-phase stator current after per-unit processing. It is an electrical angle.

[0052] Specifically, in step S3, the aim is to overcome sensor measurement errors and high-frequency electromagnetic noise interference in the actual operating environment. Based on the continuous integration to obtain the positive and negative bias values, the system introduces a preset judgment threshold to discretize the continuous data. Based on a rigorous theoretical analysis of the evolution characteristics of the limiting current, to ensure the robustness of the algorithm, the system strictly defines the preset threshold within a value range greater than 0 and less than 5 / 12. In the specific execution logic, when the extracted positive bias is greater than or equal to the preset judgment threshold, its positive bias parameter is forced to be 1; similarly, when the calculated negative bias is less than or equal to the negative judgment threshold, its negative bias parameter is forced to be -1. If neither type of bias triggers the preset threshold boundary, it indicates that the current operation within this half-wave period is within the normal fluctuation range, and the corresponding bias values ​​are all 0. After completing the basic discretization judgment, the system further performs algebraic synthesis on the single-phase bias characteristics to calculate the comprehensive bias state quantity and absolute bias state quantity of each phase. Specifically, the parameter reflecting polarity shift is obtained by adding the positive and negative biases of each phase, and the parameter reflecting waveform integrity is obtained by adding their absolute values. In a fully healthy drive system, the comprehensive bias state value within a single fundamental cycle should be 0, and the absolute bias state value should be maintained at a reference level of 2. When a phase experiences a half-cycle waveform loss, its absolute bias state value will drop directly to 1.

[0053] Therefore, the fault current waveform can be processed into Figure 3 The form makes the fault characteristics more obvious. Figure 3 Yellow represents the processing result of the first phase current, green represents the processing result of the second phase current, and red represents the processing result of the third phase current. The vertical axis represents the current processing result, and the horizontal axis represents the phase angle in radians.

[0054] Specifically, in step S4, the overall fault identification variable for global system diagnosis is constructed using the phase state parameters after discretization and algebraic synthesis. The system calculates the overall bias loss variable using a set formula, specifically by subtracting the sum of the absolute values ​​of the three-phase bias state quantities from a fixed constant. This variable can very sensitively characterize the overall loss of the three-phase current bias, thereby effectively distinguishing different macroscopic fault types such as single-phase double-tube open circuit, open circuit of two tubes on the same side but different phases, and open circuit of two tubes on different sides but different phases. To further achieve precise fault location, the system introduces a weighted approach to calculate the fault location variable, assigning weight coefficients of 1, 2, and 4 to the combined bias state quantities of the first, second, and third phases, respectively, and then summing them.

[0055] The calculation formula for step S4 is: in, For the fault indicator variable indicating loss, For specific fault location, fault identifier variables, It is the sum of the absolute values ​​of the positive and negative biases of the first phase. It is the sum of the absolute values ​​of the positive and negative biases of the second phase. It is the sum of the absolute values ​​of the positive and negative biases of the third phase. This is the sum of the positive and negative bias degrees of the first phase. This is the sum of the positive and negative bias degrees of the second phase. It is the sum of the positive and negative biases of the third phase.

[0056] In step S5, the overall bias loss variable obtained in real-time calculation is combined with the fault location variable to form a feature vector, which is then submitted to the system's built-in fault feature mapping table for high-speed lookup and comparison, thereby directly outputting the specific switch location where the open-circuit fault occurred. The fault features are summarized in Table 1, which can quickly and clearly distinguish between two-tube open-circuit faults.

[0057] Table 1. Correspondence Table of Fault Diagnosis Judgment Rules

[0058] Among them, S a1 For the first phase upper tube, S a2 For the first phase lower tube, S b1 For the second phase upper tube, S b2 For the second phase lower tube, S c1 For the third phase upper tube, S c2 This is the lower tube of the third phase.

[0059] To further verify the effectiveness of this embodiment, a specific experimental verification platform is used to detail the evolution of characteristic variables and rapid diagnostic performance of the above-mentioned current bias-based diagnostic method under real physical environments and different operating conditions.

[0060] To verify the accuracy of the theory and fault diagnosis strategy, a complete motor drive experimental platform was built. The test platform uses a surface-mounted permanent magnet synchronous motor, and the control carrier frequency and sampling frequency of the inverter are both set to 10kHz. The core system parameters are set as follows: rated speed 1500r / min, number of pole pairs 4, stator resistance 0.64Ω, stator inductance 2.63mH, DC bus voltage 400V, and rated torque 10N·m.

[0061] Figure 4 Demonstrated power device S a1 and S b1 The experimental results showed that an open-circuit fault occurred simultaneously. Figure 4In the middle (a), the power device S is shown. a1 and S b1 Three-phase current diagram showing simultaneous open-circuit faults. Figure 4 (b) represents the power device S. a1 and S b1 Simultaneously, the first phase stator current diagram after per-unit processing for open-circuit faults. Figure 4 (c) represents the power device S. a1 and S b1 Simultaneously, the per-unit processing of the second-phase stator current diagram after an open-circuit fault occurs. Figure 4 In the middle (d), S represents the power device. a1 and S b1 The third-phase stator current diagram after per-unit processing for simultaneous open-circuit faults. Figure 4 In the middle (e), S represents the power device. a1 and S b1 Simultaneous loss of open circuit faults, fault identifier variable diagram. Figure 4 In the middle (f), S represents the power device. a1 and S b1 Simultaneously, the specific fault location and fault identification variable diagram of the open circuit fault occurred. Figure 4 The motor speed in the experiment shown is 500 r / min, and the load torque is 5 N·m.

[0062] In a healthy state, A pulse with an amplitude of 1, a duty cycle of 0.5, and a period of 30ms has an average value of 0.5. S a1 and S b1 The fault occurred =0 at time. When the fault occurs, i b <0, only S a1 This affects system operation, causing the loss of the positive half-cycle of the first-phase current, thus affecting the per-unit processed first-phase stator current i. af_N Less than or equal to 0. S a1 Three ms after an open-circuit fault occurs, D changes from 0 to 1, indicating a half-wave loss, i.e., a single transistor open circuit; furthermore, r changes from 0 to -1, indicating an S fault. a1 For a single open circuit, the required fault diagnosis time is 0.1 cycles.

[0063] Upon detection of a fault (pink dashed line), the diagnostic threshold is dynamically adjusted to 0.3. Furthermore, the third-phase current is gradually affected, causing the per-unit processed second-phase stator current to... Less than or equal to 0 (red dashed line), the third-phase stator current after per-unit processing Greater than or equal to 0. After 12.4ms, three half-waves were detected to be lost (blue dashed line), at which point r becomes 1, indicating that an S-wave loss has occurred. a1 and Sb1 For open-circuit faults, the required fault diagnosis time is 0.52 cycles.

[0064] Specifically, the formula for dynamically adjusting the diagnostic threshold is as follows: in, The diagnostic threshold is dynamically adjusted. The first threshold, For symbolic functions, This is the second threshold.

[0065] Figure 5 Demonstrated power device S a1 and S b2 The experimental results of an open-circuit fault occurring at times. Figure 5 In the middle (a), the power device S is shown. a1 and S b2 Three-phase current diagram showing simultaneous open-circuit faults. Figure 5 (b) represents the power device S. a1 and S b2 Simultaneously, the first phase stator current diagram after per-unit processing for open-circuit faults. Figure 5 (c) represents the power device S. a1 and S b2 Simultaneously, the per-unit processing of the second-phase stator current diagram after an open-circuit fault occurs. Figure 5 In the middle (d), S represents the power device. a1 and S b2 The third-phase stator current diagram after per-unit processing for simultaneous open-circuit faults. Figure 5 In the middle (e), S represents the power device. a1 and S b2 Simultaneous loss of open circuit faults, fault identifier variable diagram. Figure 5 In the middle (f), S represents the power device. a1 and S b2 Simultaneously, the specific fault location and fault identification variable diagram of the open circuit fault occurred. Figure 5 The motor speed in the experiment shown is 800 r / min, and the load torque is 2 N·m.

[0066] In a healthy state, The pulse has an amplitude of 1, a duty cycle of 0.5, and a period of 18.4 ms, with an average value of 0.5. S a1 and S b2 The fault occurred =5π / 3 (pink dashed line). When the fault occurs, the first phase current is less than 0, only S... b2 This affects system operation, causing the loss of the negative half-cycle of the second-phase current, thereby... Less than or equal to 0. Sb2 2.4ms after an open-circuit fault occurs, D changes from 0 to 1, indicating a half-wave loss, i.e., a single transistor open circuit (red dashed line); further, r changes from 0 to 2, indicating a single transistor open circuit in Sb2, with a required fault diagnosis time of 0.13 cycles. After the fault is detected, the diagnostic threshold is dynamically adjusted to 0.3. After 4.4ms, two half-wave losses are detected, at which point r becomes 1 (blue dashed line), indicating that Sa1 and S... b2 For open-circuit faults, the required fault diagnosis time is 0.38 cycles.

[0067] like Figure 6 As shown below, an inverter open-circuit diagnostic system based on dynamic current per unit provided by the present invention will be described. The inverter open-circuit diagnostic system based on dynamic current per unit described below can be referred to in correspondence with the inverter open-circuit diagnostic method based on dynamic current per unit described above.

[0068] Current acquisition module 101: used to acquire the three-phase stator current of the three-phase inverter drive system in real time, construct current characteristic information using natural constant, and obtain the three-phase stator current after per-unit processing; Bias calculation module 102: used to integrate the normalized three-phase stator current to calculate the positive bias and negative bias of the phase current. State parameter calculation module 103: used to set the judgment threshold and convert the positive bias and the negative bias of the phase current into dynamic per-unit current bias state parameters. Fault variable calculation module 104: used to calculate fault identification variables based on dynamically standardized current bias state parameters; Fault Judgment Module 105: Used to match fault diagnosis and judgment rules with fault identifier variables to locate the specific switch where an open circuit fault occurs.

[0069] Figure 7 An example is a schematic diagram of the physical structure of an electronic device, such as... Figure 7 As shown, the electronic device may include: a processor 810, a communication interface 820, a memory 830, and a communication bus 840, wherein the processor 810, the communication interface 820, and the memory 830 communicate with each other through the communication bus 840. The processor 810 can call logic instructions in the memory 830 to execute an inverter open-circuit diagnosis method based on dynamic current per unit, the method including: S1: Real-time acquisition of the three-phase stator current of the three-phase inverter drive system, construction of current characteristic information using natural constant, and obtaining the per-unit processed three-phase stator current; S2: The positive bias and negative bias of the phase current are calculated by integrating the normalized three-phase stator current. S3: Set the judgment threshold to convert the positive bias and the negative bias of the phase current into dynamically standardized current bias state parameters. S4: Calculate the fault identification variable based on the dynamically standardized current bias state parameters; S5: Based on the fault identifier variable, match the fault diagnosis and judgment rules to locate the specific switch where the open circuit fault occurred.

[0070] Furthermore, the logical instructions in the aforementioned memory 830 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0071] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0072] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0074] It should be noted that the embodiments of this disclosure can be implemented using hardware, software, or a combination of both. The hardware portion can be implemented using dedicated logic; the software portion can be stored in memory and executed by a suitable instruction execution system, such as a microprocessor or dedicated-design hardware. Those skilled in the art will understand that the above-described devices and methods can be implemented using computer-executable instructions and / or included in processor control code, for example, such code provided on a programmable memory or a data carrier such as an optical or electronic signal carrier.

[0075] Furthermore, although the operation of the methods of this disclosure is described in a specific order in the accompanying drawings, this does not require or imply that these operations must be performed in that specific order, or that all the operations shown must be performed to achieve the desired result. Rather, the steps depicted in the flowcharts may be performed in a different order. Additionally or alternatively, certain steps may be omitted, multiple steps may be combined into one step, and / or one step may be broken down into multiple steps. It should also be noted that the features and functions of two or more devices according to this disclosure may be embodied in one device. Conversely, the features and functions of one device described above may be further divided and embodied by multiple devices.

[0076] While this disclosure has been described with reference to several specific embodiments, it should be understood that this disclosure is not limited to the specific embodiments disclosed. This disclosure is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. A method for open-circuit diagnosis of inverters based on dynamic per-unit current, characterized in that, include: S1: Real-time acquisition of the three-phase stator current of the three-phase inverter drive system, construction of current characteristic information using natural constant, and obtaining the per-unit processed three-phase stator current; S2: The positive bias and negative bias of the phase current are calculated by integrating the normalized three-phase stator current. S3: Set a judgment threshold to convert the positive bias and the negative bias of the phase current into dynamically standardized current bias state parameters; the current bias state parameters include positive bias state parameters and negative bias state parameters. When the positive bias is greater than or equal to the preset threshold, the positive bias state parameter takes the value of 1; when the negative bias is less than or equal to the preset threshold, the negative bias state parameter takes the value of -1. All other current bias state parameters are set to 0; S4: Calculate the fault identification variable based on the dynamically standardized current bias state parameters; the calculation formula for step S4 is: in, For the fault indicator variable indicating loss, For specific fault location, fault identifier variables, It is the sum of the absolute values ​​of the positive and negative biases of the first phase. It is the sum of the absolute values ​​of the positive and negative biases of the second phase. It is the sum of the absolute values ​​of the positive and negative biases of the third phase. This is the sum of the positive and negative bias degrees of the first phase. This is the sum of the positive and negative bias degrees of the second phase. This is the sum of the positive and negative biases of the third phase; S5: Based on the fault identification variable and the fault diagnosis judgment rule, locate the specific switch where the open circuit fault occurred. The fault diagnosis judgment rule in step S5 is as follows: when D =1 ，r When =-1, S a1 Error; when D =1 ，r When =1, S a2 mistake; when D =1 ，r When =-2, S b1 Error; when D =1 ，r When =2, S b2 mistake; when D =1 ，r When =-4, S c1 Error; when D =1 ，r When =4, S c2 mistake; when D =3 ，r When =1, S a1 and S b1 Error; when D =2 ，r When =1, S a1 and S b2 mistake; when D =3 ，r When =-1, S a2 and S b2 Error; when D =2 ，r When =-1, S a2 and S b1 mistake; when D =3 ，r When =3, S a2 and S c2 Error; when D =2 ，r When =2, S b1 and S c2 mistake; when D =3 ，r When =-3, S a1 and S c1 Error; when D =2 ，r When =-2, S b2 and S c1 mistake; when D =3 ，r When =5, S b2 and S c2 Error; when D =2 ，r When =3, S a1 and S c2 mistake; when D =3 ，r When =-5, S b1 and S c1 Error; when D =2 ，r When =-3, S a2 and S c1 mistake; when D =0 ，r When =0, everything is normal; Among them, S a1 For the first phase upper tube, S a2 For the first phase lower tube, S b1 For the second phase upper tube, S b2 For the second phase lower tube, S c1 For the third phase upper tube, S c2 This is the lower tube of the third phase.

2. The inverter open-circuit diagnosis method based on dynamic current per-unit as described in claim 1, characterized in that, The calculation formula for step S1 is: in, This refers to the three-phase stator current after per-unit processing. For three-phase stator current, These are the per-unit parameters.

3. The inverter open-circuit diagnosis method based on dynamic current per-unit as described in claim 1, characterized in that, The calculation formula for step S2 is: in, This is a positive bias. It is a negative bias. This refers to the three-phase stator current after per-unit processing. It is an electrical angle.

4. The inverter open-circuit diagnosis method based on dynamic current per-unit as described in claim 1, characterized in that, The preset threshold is greater than 0 and less than 5 / 12.

5. The inverter open-circuit diagnosis method based on dynamic current per-unit as described in claim 1, characterized in that, This method is applicable to dual-inverter architecture systems, where one inverter is connected to a photovoltaic power generation unit and the other inverter is connected to a battery energy storage unit. This method achieves cross-topology open-circuit protection for power devices by monitoring the current bias state on the AC side of both inverters.

6. An inverter open-circuit diagnostic system based on dynamic current per unit, used to execute the inverter open-circuit diagnostic method based on dynamic current per unit as described in any one of claims 1 to 5, characterized in that, Includes the following modules: Current acquisition module: used to acquire the three-phase stator current of the three-phase inverter drive system in real time, construct current characteristic information using natural constant, and obtain the three-phase stator current after per-unit processing; Offset Calculation Module: Used to integrate the normalized three-phase stator current to calculate the positive and negative offset of the phase current. State parameter calculation module: used to set the judgment threshold and convert the positive bias and the negative bias of the phase current into dynamic per-unit current bias state parameters. Fault Variable Calculation Module: Used to calculate fault identification variables based on dynamically standardized current bias state parameters; Fault diagnosis module: Used to locate the specific switch where an open circuit fault occurs by matching the fault identifier variable with the fault diagnosis and judgment rules.

7. An electronic device comprising a processor, a communication interface, a memory, and a communication bus, characterized in that, When the processor executes the computer program, it implements the steps of the inverter open-circuit diagnosis method based on current dynamic per-unit as described in any one of claims 1 to 5.

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