Single-phase four-quadrant rectifier IGBT open-circuit fault diagnosis method under multiple working conditions

Abstract

The invention provides a single-phase four-quadrant rectifier IGBT open-circuit fault diagnosis method under multiple working conditions, and relates to the technical field of IGBT fault diagnosis. Historical data of alternating current side voltage, alternating current side current and direct current side voltage of the single-phase four-quadrant rectifier are obtained, and a total harmonic distortion rate threshold value, a direct current side voltage threshold value and an alternating current side current first threshold value are obtained. And constructing and training an IGBT open-circuit fault positioning identification model. Detecting the total harmonic distortion rate of the alternating-current side current of the single-phase four-quadrant rectifier in real time, if the total harmonic distortion rate exceeds a threshold value, entering fault positioning, collecting and calculating the average value of the direct-current side voltage and the alternating-current side current in the period, and judging the fault of the single-phase four-quadrant rectifier under the specific working condition according to the comparison of the average value and the threshold value. Or using an IGBT open-circuit fault positioning identification model to diagnose the fault; if the threshold value is not exceeded, the next period is continuously monitored. According to the invention, the IGBT fault diagnosis efficiency and accuracy of the single-phase four-quadrant rectifier are improved.

Description

Technical Field

[0001] This invention belongs to the technical field of IGBT fault diagnosis, and more specifically, relates to a method for diagnosing open-circuit faults in single-phase four-quadrant rectifier IGBTs under multiple operating conditions. Background Technology

[0002] Single-phase four-quadrant rectifiers are widely used in high-speed trains, playing a role in the efficient conversion of AC and DC power and the control of energy flow. Among them, the insulated gate bipolar transistor (IGBT) is an important component of the single-phase pulse width modulation (PWM) rectifier, but it is also a weak link in the rectifier. It is prone to failure due to harsh operating conditions such as high temperature or overvoltage, and the failure mode is mostly open circuit failure.

[0003] Existing technologies for diagnosing IGBT open-circuit faults in single-phase rectifiers have the following shortcomings. First, four-quadrant rectifiers operate not only in rectification mode but also in inverter mode, and IGBT open-circuit faults can occur in both modes. Current methods only address open-circuit faults occurring in rectification mode, neglecting fault diagnosis in inverter mode, thus making it impossible to diagnose IGBT open-circuit faults occurring in inverter mode. Second, rectifier failure is a low-probability event, but existing methods perform fault diagnosis regardless of whether the rectifier is in a normal or faulty state. This involves continuous data sampling and frequent calls to the diagnostic model, leading to a significant increase in computational resource utilization, frequent memory fluctuations, and increased device power consumption due to the large amount of real-time data and computation. Furthermore, the lack of enabling conditions for triggering fault diagnosis when transitioning from a normal to a faulty state results in a substantial increase in computational load.

[0004] Furthermore, during fault diagnosis, the size and validity of the collected data determine the computational load and the accuracy of the diagnosis. The data length should be as short as possible but effective. However, how to collect effective data to ensure the accuracy of the diagnosis is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] To address the issues of low efficiency and poor accuracy in existing IGBT fault diagnosis methods for single-phase four-quadrant rectifiers, this invention provides a multi-condition IGBT open-circuit fault diagnosis method for single-phase four-quadrant rectifiers, thereby improving the efficiency and accuracy of IGBT fault diagnosis for single-phase four-quadrant rectifiers.

[0006] To achieve the above-mentioned technical effects, the technical solution of the present invention is as follows: S1: Obtain historical data of AC side voltage, AC side current, and DC side voltage of a single-phase four-quadrant rectifier over several complete operating cycles; S2: Based on the historical data described in S1, obtain the total harmonic distortion rate threshold, the DC side voltage threshold, and the first AC side current threshold. S3: Construct an IGBT open circuit fault location and identification model, and train the IGBT open circuit fault location and identification model based on historical data to obtain a trained IGBT open circuit fault location and identification model. S4: After the AC side voltage crosses zero, the AC side current of the single-phase four-quadrant rectifier is collected in real time, the total harmonic distortion rate of the AC side current in a complete working cycle is calculated, and step S5 is executed. S5: If the total harmonic distortion rate is greater than the set total harmonic distortion rate threshold, an IGBT open circuit fault occurs. At the beginning of the next cycle, the fault location stage is entered and step S6 is executed; otherwise, step S7 is executed. S6: Real-time acquisition of DC side voltage and AC side current of the single-phase four-quadrant rectifier under test in this cycle, and calculation of the average value A of DC side voltage and the average value B of AC side current in this cycle, and execution of step S8. S7: Collect the AC side current of the single-phase four-quadrant rectifier in the next complete working cycle, calculate the total harmonic distortion rate of the AC side current, and return to S5. S8: If the average value B is less than the first threshold of the AC side current, execute S9; otherwise, execute S10. S9: If the average value A is greater than the DC side voltage threshold, the single-phase four-quadrant rectifier IGBT will experience an inverter operation fault; otherwise, proceed to the single-phase four-quadrant rectifier IGBT double tube fault judgment process. S10: Extract the data segments corresponding to the AC side current and DC side voltage within this cycle, preprocess the data segments to obtain the feature vector; input the feature vector into the trained IGBT open circuit fault location and identification model, and use the IGBT open circuit fault location and identification model to diagnose the IGBT fault of the single-phase four-quadrant rectifier.

[0007] Furthermore, the process of obtaining the total harmonic distortion rate threshold is as follows: Set a sliding window with a fixed length and step size for data interception. Take the zero-crossing point of the AC side voltage as the starting point for data interception. The AC side current is intercepted based on the sliding window, and linear interpolation is used to supplement the intercepted AC side current. Using the Fast Fourier Transform (FFT) method, based on the intercepted AC side current, the total harmonic distortion (THD) values ​​within different complete duty cycles are calculated. The expression for calculating the THD is as follows:

[0008] In the formula, This indicates the calculation of total harmonic distortion (THD). This represents the effective value of the Kth harmonic current. This represents the effective value of the fundamental current, and n represents the highest harmonic order. The total harmonic distortion rate (THD) values ​​of a single-phase four-quadrant rectifier with and without IGBT failure are compared to obtain the THD threshold.

[0009] Furthermore, a sliding window with a fixed length and step size is set for data interception. The zero-crossing point of the AC side voltage is used as the starting point for data interception. The DC side voltage is intercepted within several complete working cycles based on the sliding window. Based on the intercepted DC side voltage, the average DC side voltage of the data segment within the sliding window is calculated. The average DC side voltage of the single-phase four-quadrant rectifier IGBT under inverter operation fault and rectifier dual-tube fault is compared to obtain the DC side voltage threshold. The AC current is captured within several complete operating cycles using a sliding window. Based on the captured AC current, the average AC current of the data segment within the sliding window is calculated. The average AC current of the single-phase four-quadrant rectifier IGBT under rectification conditions for TIT4 and T2T3 faults is compared with the average AC current of faults under other rectification conditions to obtain a first threshold for AC current. The average AC current of the single-phase four-quadrant rectifier IGBT under rectification conditions for TIT4 and T2T3 faults is compared with the average AC current of the single-phase four-quadrant rectifier IGBT under inverter conditions for T1T4 and T2T3 faults to obtain a second threshold for AC current.

[0010] Furthermore, the process for determining a dual-transistor fault in the rectification mode of a single-phase four-quadrant rectifier IGBT is as follows: if the average value B is less than the second threshold of the AC side current, the single-phase four-quadrant rectifier IGBT experiences a rectification mode TIT4 or T2T3 fault; otherwise, the single-phase four-quadrant rectifier IGBT experiences other faults in the inverter mode.

[0011] Furthermore, the IGBT open-circuit fault location and identification model includes: an input layer, a hidden layer, and an output layer; First, the input layer of the IGBT open-circuit fault location and identification model receives feature vectors; then, the output of the input layer is input to the hidden layer, in which the number of hidden layer nodes is set, the input weights and biases of the hidden layer are randomly initialized, the parameter hidden layer performs a weighted summation of the input feature vectors, and performs a nonlinear transformation through an activation function; the output layer outputs the IGBT fault diagnosis results of the single-phase four-quadrant rectifier. The operation expression for the hidden layer is as follows:

[0012]

[0013] In the formula, Represents the eigenvector. Represents the hidden layer matrix. This represents the output of the hidden layer. ω Indicates the input weights of the hidden layer. Indicates the bias of the hidden layer. This represents the input weights of the hidden layer.

[0014] Furthermore, the process of training the IGBT open-circuit fault location and identification model based on historical data is as follows: S301: Extract the data segments corresponding to AC side current and DC side voltage, and construct historical feature vectors; S302: Construct a dataset from historical feature vectors and divide the dataset into a training set and a test set; S303: Initialize the number of hidden nodes in the IGBT open-circuit fault location and identification model; randomly generate the weights of the hidden layer nodes. and bias b; S304: Input the historical feature vectors of the training set into the IGBT open-circuit fault location and recognition model to obtain the fault detection results and derive the output weights. ; S305: Based on the derived output weights The trained IGBT open-circuit fault location and identification model is obtained. S306: Input the test set into the trained IGBT open circuit fault location and identification model to verify the performance of the trained IGBT open circuit fault location and identification model.

[0015] Furthermore, the process of extracting the data segments corresponding to the AC side current and DC side voltage within this cycle is as follows: Set a sliding window with length S and step size S for extracting data, take the zero-crossing point of the AC side voltage as the starting point for data extraction, and perform sliding extraction of the AC side current and DC side voltage based on the sliding window of length S to obtain AC side current and DC side voltage data segments of length S.

[0016] Furthermore, the preprocessing includes: normalizing the AC side current and DC side voltage data segments respectively, and concatenating them into a feature vector; The expression for the per-unit processing is:

[0017] In the formula, The per-unit value representing the AC side current. Indicates the alternating current. Indicates the reference value of the AC side current. Indicates the equivalent resistance of the load. Indicates the AC side voltage. The per-unit value representing the DC-side voltage. Indicates the DC side voltage. Indicates the reference value of the DC side voltage; The expression for the feature vector is: X i =[ ] In the formula, X i This represents the eigenvector.

[0018] Furthermore, a single-phase four-quadrant rectifier model was built on the simulation platform to simulate the operating conditions of IGBTs under rectification and inverter conditions, including single and double tube open-circuit faults and no faults. The AC side voltage, AC side current and DC side voltage were continuously collected over several complete working cycles. The load resistance value of the single-phase four-quadrant rectifier was changed to collect historical data of open-circuit faults under different loads.

[0019] This application also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the multi-condition single-phase four-quadrant rectifier IGBT open-circuit fault diagnosis program is executed by the processor, it implements the steps of the multi-condition single-phase four-quadrant rectifier IGBT open-circuit fault diagnosis method.

[0020] Compared with existing technologies, the beneficial effects of this method are: This invention provides a method for diagnosing IGBT open-circuit faults in a single-phase four-quadrant rectifier under multiple operating conditions. First, historical data of AC-side voltage, current, and DC-side voltage of the single-phase four-quadrant rectifier are acquired over several complete operating cycles. A total harmonic distortion (THD) threshold, a DC-side voltage threshold, and a first threshold for AC-side current are also obtained. An IGBT open-circuit fault location and identification model is then constructed and trained. During online detection, fault detection is triggered by the THD threshold, avoiding fault diagnosis even when the single-phase four-quadrant rectifier is not faulty. If the threshold is exceeded, an IGBT open-circuit fault is determined, and the fault location process begins, reducing the computational load and resource consumption associated with frequent calls to the diagnostic model. In fault location, the DC-side voltage and AC-side current within the current cycle are collected and their average values ​​are calculated. If the average AC-side current is less than the first threshold, the relationship between the average DC-side voltage and the corresponding threshold is used to determine whether the fault is due to inverter operation or a fault in the lower TIT4 or T2T3 dual-transistor configuration under rectifier operation. Otherwise, the data segment is preprocessed to obtain a feature vector, which is then input into the trained model for fault diagnosis. The fault diagnosis method of this invention enables rapid identification and precise location of IGBT open-circuit faults, improving the efficiency and accuracy of IGBT fault diagnosis for single-phase four-quadrant rectifiers. Attached Figure Description

[0021] Figure 1 A flowchart illustrating the method for diagnosing open-circuit faults of single-phase four-quadrant rectifier IGBTs under multiple operating conditions proposed in this embodiment of the invention; Figure 2 This diagram illustrates the circuit schematic of the single-phase four-quadrant rectifier proposed in this embodiment of the invention. Figure 3 This is a block diagram illustrating the principle of open-circuit fault detection and localization of a single-phase four-quadrant rectifier IGBT proposed in this embodiment of the invention. Figure 4 This is a schematic diagram illustrating the electronic device proposed in an embodiment of the present invention. Detailed Implementation

[0022] The accompanying drawings are for illustrative purposes only and should not be construed as limiting the scope of this patent. To better illustrate this embodiment, some parts of the accompanying drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions; It is understandable to those skilled in the art that some well-known details may be omitted from the accompanying drawings.

[0023] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0024] The positional relationships depicted in the accompanying drawings are for illustrative purposes only and should not be construed as limiting this patent. Example 1 This embodiment proposes a method for diagnosing open-circuit faults in single-phase four-quadrant rectifier IGBTs under multiple operating conditions, such as... Figure 1 The flowchart shown illustrates the method, and the method proposed in this embodiment generally includes the following steps: S1: Obtain historical data of AC side voltage, AC side current, and DC side voltage of a single-phase four-quadrant rectifier over several complete operating cycles; S2: Based on the historical data described in S1, obtain the total harmonic distortion rate threshold, the DC side voltage threshold, and the first AC side current threshold. S3: Construct an IGBT open circuit fault location and identification model, and train the IGBT open circuit fault location and identification model based on historical data to obtain a trained IGBT open circuit fault location and identification model. S4: After the AC side voltage crosses zero, the AC side current of the single-phase four-quadrant rectifier is collected in real time, the total harmonic distortion rate of the AC side current in a complete working cycle is calculated, and step S5 is executed. S5: If the total harmonic distortion rate is greater than the set total harmonic distortion rate threshold, an IGBT open circuit fault occurs. At the beginning of the next cycle, the fault location stage is entered and step S6 is executed; otherwise, step S7 is executed. S6: Real-time acquisition of DC side voltage and AC side current of the single-phase four-quadrant rectifier under test in this cycle, and calculation of the average value A of DC side voltage and the average value B of AC side current in this cycle, and execution of step S8. S7: Collect the AC side current of the single-phase four-quadrant rectifier in the next complete working cycle, calculate the total harmonic distortion rate of the AC side current, and return to S5. S8: If the average value B is less than the first threshold of the AC side current, execute S9; otherwise, execute S10. S9: If the average value A is greater than the DC side voltage threshold, the single-phase four-quadrant rectifier IGBT will experience an inverter operation fault; otherwise, proceed to the single-phase four-quadrant rectifier IGBT double tube fault judgment process. S10: Extract the data segments corresponding to the AC side current and DC side voltage within this cycle, preprocess the data segments to obtain the feature vector; input the feature vector into the trained IGBT open circuit fault location and identification model, and use the IGBT open circuit fault location and identification model to diagnose the IGBT fault of the single-phase four-quadrant rectifier.

[0025] In this embodiment, a single-phase four-quadrant rectifier model is built on a simulation platform, such as Matlab's Simulink, to simulate the IGBT under rectification and inverter conditions with single and double open-circuit faults and no faults. The AC side voltage Us and AC side current I are continuously collected over several complete operating cycles. s and DC side voltage U dc Furthermore, the load resistor value of the single-phase four-quadrant rectifier was changed, and historical data of open-circuit faults under different loads were collected.

[0026] like Figure 2 The circuit diagram of the single-phase four-quadrant rectifier proposed in this embodiment is shown. The switching module consists of four IGBTs (T1, T2, T3, and T4), with four freewheeling diodes (D1, D2, D3, and D4) connected in anti-parallel and arranged in an H-bridge structure. The AC side consists of AC voltage and the equivalent inductance of the grid side. Ls and grid-side equivalent resistance Rs These are connected in series and respectively to the midpoints of switches T1 and T2 and switches T3 and T4 in the H-bridge. The DC side is composed of a DC-side capacitor. and equivalent load It is formed in parallel with the H-bridge of the switching module.

[0027] The zero-crossing point of the AC side voltage is determined by detecting the product of two adjacent data points of the AC side voltage. When Us(i)*Us(i-1)<0, Us(i) is taken as the zero-crossing point of the AC side voltage.

[0028] In this embodiment, the process of obtaining the total harmonic distortion rate threshold is as follows: A sliding window with a fixed length and step size is set for data interception. The AC side voltage zero-crossing point is used as the starting point for data interception. The AC side current is intercepted based on the sliding window, and linear interpolation is used to supplement the intercepted AC side current, increasing the number of data points from 2000 to 2048.

[0029] Using the Fast Fourier Transform (FFT) method, the total harmonic distortion (THD) is calculated based on the intercepted AC current within different complete duty cycles. The expression for calculating the THD is as follows:

[0030] In the formula, This indicates the calculation of total harmonic distortion (THD). This represents the effective value of the Kth harmonic current. This represents the effective value of the fundamental current, and n represents the highest harmonic order. The total harmonic distortion rate (THD) values ​​of a single-phase four-quadrant rectifier with and without IGBT failure are compared to obtain the THD threshold.

[0031] For example, in rectifier operation without faults, the total harmonic distortion (THD) is greater than 9 but less than 10; in single-tube faults, it is between 20 and 30, typically around 23; and in dual-tube faults, it is above 30. In inverter operation without faults, the THD is around 16; and in faults, it is above 30. In operation without faults, the THD does not exceed 20; in faults, it exceeds 20.

[0032] A sliding window with a fixed length and step size is set for data interception. The AC side voltage zero-crossing point is used as the starting point for data interception. The DC side voltage is intercepted within several complete working cycles based on the sliding window. Based on the intercepted DC side voltage, the average DC side voltage of the data segment within the sliding window is calculated. The average DC side voltage of the single-phase four-quadrant rectifier IGBT under inverter operation fault and rectifier dual-tube fault is compared to obtain the DC side voltage threshold.

[0033] In this embodiment, if the average value A is greater than the DC side voltage threshold, the single-phase four-quadrant rectifier IGBT experiences an inverter operation fault. Inverter operation faults include: T1T2, T1T3, T2T4, and T3T4 faults.

[0034] For example, in this embodiment, the DC-side voltage value is set to 1.1. The AC current is captured within several complete operating cycles using a sliding window. Based on the captured AC current, the average AC current of the data segment within the sliding window is calculated. The average AC current of the single-phase four-quadrant rectifier IGBT under rectification conditions for TIT4 and T2T3 faults is compared with the average AC current of faults under other rectification conditions to obtain a first threshold for AC current. The average AC current of the single-phase four-quadrant rectifier IGBT under rectification conditions for TIT4 and T2T3 faults is compared with the average AC current of the single-phase four-quadrant rectifier IGBT under inverter conditions for T1T4 and T2T3 faults to obtain a second threshold for AC current.

[0035] For example, the first threshold for AC side current can be set to 0.05. The second threshold for AC side current can be set to 0.01.

[0036] For example, when the power frequency period is 20ms and the sampling frequency is 100kHz, the length of the sliding window is set to 500, which represents the number of points sampled by the system within the period, and the step size is 1000.

[0037] For example, the length of the sliding window is set to 2000, which represents the number of points sampled by the system within a period, with a step size of 2000.

[0038] In this embodiment, the process for determining a dual-tube fault in the rectification mode of a single-phase four-quadrant rectifier IGBT is as follows: if the average value B is less than the second threshold of the AC side current, the single-phase four-quadrant rectifier IGBT experiences a rectification mode TIT4 or T2T3 fault; otherwise, the single-phase four-quadrant rectifier IGBT experiences other faults in the inverter mode.

[0039] like Figure 3The diagram shown illustrates the principle block diagram for IGBT open-circuit fault detection and localization in a single-phase four-quadrant rectifier. The IGBT open-circuit fault diagnosis method for a single-phase four-quadrant rectifier under multiple operating conditions proposed in this embodiment can be divided into offline and online parts. In the offline part, a simulated single-phase four-quadrant rectifier model built under experimental conditions is used to simulate faults and obtain historical data on AC side voltage, AC side current, and DC side voltage. Based on the historical data, thresholds for total harmonic distortion (THD), DC side voltage, AC side current, and AC side current are set, and a feature vector X is constructed to obtain a training set X_train, which is used to train the constructed IGBT open-circuit fault localization and identification model. In the online part, it can be divided into fault detection and fault localization. In fault detection, the THD of the AC side current of the single-phase four-quadrant rectifier is detected in real time. If it exceeds the threshold, fault localization is initiated; otherwise, monitoring continues for the next cycle. In fault location, the average values ​​of DC-side voltage and AC-side current for the current cycle are collected and calculated. If the average AC-side current is less than a first threshold, the relationship between the average DC-side voltage and the corresponding threshold is used to determine whether the fault is in inverter operation or a dual-transistor fault (TIT4 and T2T3) in rectifier operation. Otherwise, the data segment is preprocessed to obtain a feature vector, which is then input into the trained model for fault diagnosis, yielding the IGBT fault diagnosis result for the single-phase four-quadrant rectifier. Specifically, when judging whether a single-phase four-quadrant rectifier IGBT experiences a dual-transistor fault (TIT4 and T2T3) in rectifier operation, if the average AC-side current is less than a second threshold, then the single-phase four-quadrant rectifier IGBT experiences a fault (TIT4 and T2T3) in rectifier operation; otherwise, other faults in inverter operation occur.

[0040] The multi-condition IGBT open-circuit fault diagnosis method for single-phase four-quadrant rectifiers proposed in this embodiment analyzes and diagnoses not only the rectification condition of the single-phase four-quadrant rectifier but also the inverter condition. By adding an anomaly detection mechanism before fault diagnosis, the fault diagnosis stage is only initiated when an anomaly occurs, avoiding the problem of performing fault diagnosis when the rectifier is fault-free, thus reducing the computational load. The zero-crossing point of the AC side voltage Us is used as the sampling start signal, and the data segments are uniformly retained to ensure that the data is concise yet effective. A method combining a data-driven ELM algorithm and waveform features is adopted to reduce the amount of data and computation, and improve the accuracy and speed of diagnosis.

[0041] Example 2 In this embodiment, the construction and training of the IGBT open-circuit fault location and identification model mentioned in Embodiment 1 will be described in detail.

[0042] The IGBT open-circuit fault location and identification model includes: an input layer, a hidden layer, and an output layer; First, the input layer of the IGBT open-circuit fault location and identification model receives feature vectors; then, the output of the input layer is input to the hidden layer, in which the number of hidden layer nodes is set, the input weights and biases of the hidden layer are randomly initialized, the parameter hidden layer performs a weighted summation of the input feature vectors, and performs a nonlinear transformation through an activation function; the output layer outputs the IGBT fault diagnosis results of the single-phase four-quadrant rectifier. The operation expression for the hidden layer is as follows:

[0043]

[0044] In the formula, Represents the eigenvector. Represents the hidden layer matrix. This represents the output of the hidden layer. ω Indicates the input weights of the hidden layer. Indicates the bias of the hidden layer. This represents the input weights of the hidden layer.

[0045] The process of training the IGBT open-circuit fault location and identification model based on historical data is as follows: S301: Extract the data segments corresponding to AC side current and DC side voltage, and construct historical feature vectors; S302: Construct a dataset from historical feature vectors and divide the dataset into a training set and a test set; S303: Initialize the number of hidden nodes in the IGBT open-circuit fault location and identification model; randomly generate the weights of the hidden layer nodes. and bias b; S304: Input the historical feature vectors of the training set into the IGBT open-circuit fault location and recognition model to obtain the fault detection results and derive the output weights. ; S305: Based on the derived output weights The trained IGBT open-circuit fault location and identification model is obtained. S306: Input the test set into the trained IGBT open circuit fault location and identification model to verify the performance of the trained IGBT open circuit fault location and identification model.

[0046] The process of extracting the data segments corresponding to the AC side current and DC side voltage within the current cycle is as follows: Set a sliding window with length S and step size S for data extraction, take the zero-crossing point of the AC side voltage as the starting point for data extraction, and perform sliding extraction of AC side current and DC side voltage based on the sliding window of length S to obtain AC side current and DC side voltage data segments of length S.

[0047] For example, with a power frequency period of 20ms and a sampling frequency of 100kHz, the length of the sliding window is set to 500, representing the number of points sampled by the system within the period, with a step size of 1000.

[0048] The data segments are electrically uniformly preserved using a uniform sampling method.

[0049] In this embodiment, the preprocessing includes: normalizing the AC side current and DC side voltage data segments respectively, and concatenating them into a feature vector; The expression for the per-unit processing is:

[0050] In the formula, The per-unit value representing the AC side current. Indicates the alternating current. Indicates the reference value of the AC side current. , Indicates the AC side voltage. The per-unit value representing the DC-side voltage. Indicates the DC side voltage. Indicates the reference value of the DC side voltage; The expression for the feature vector is: X i =[ ] In the formula, X i This represents the eigenvector.

[0051] For example, using the idea of ​​uniform sampling, a data segment of length 500 is uniformly retained as a data segment of length 50. After standardizing the data segments, two 1*50 vectors are horizontally concatenated to form a 1*100 feature vector X. i Simultaneously, a corresponding fault label Y is generated. i Synthesize historical datasets X=[X1;X2;……;Xk] and fault labels Y=[Y1;Y2;……;Yk].

[0052] Example 3 This embodiment also proposes an electronic device, such as... Figure 4 The schematic diagram shown includes a memory 101, a processor 102, and a computer program stored in the memory 101 and running on the processor 102. When the processor 102 executes the computer program, it implements the steps of the method for diagnosing open-circuit faults of single-phase four-quadrant rectifier IGBTs under multiple operating conditions proposed in this embodiment.

[0053] Specifically, in this embodiment, the processor 102 may include a central processing unit (CPU) or a specific integrated circuit, or one or more integrated circuits configured to implement this embodiment. The memory 101 may include a mass storage device for data or instructions. It may include a hard disk drive (HDD), floppy disk drive, flash memory, optical disk, magneto-optical disk, magnetic tape, or Universal Serial Bus (USB) drive, or a combination of two or more of these. Where appropriate, the memory 101 may include removable or non-removable (or fixed) media. Where appropriate, the memory 101 may be internal or external to the integrated gateway disaster recovery device.

[0054] Memory 101 may include read-only memory (ROM), random access memory (RAM), disk storage media device, optical storage media device, flash memory device, electrical, optical, or other physical / tangible memory storage device. Therefore, typically, memory includes one or more tangible (non-transitory) computer-readable storage media (e.g., memory devices) encoded with software including computer-executable instructions, and when the software is executed (e.g., by one or more processors), it is operable to perform the steps of implementing the multi-condition single-phase four-quadrant rectifier IGBT open-circuit fault diagnosis method proposed in this embodiment.

[0055] The embodiments described are merely examples to clearly illustrate the present invention and are not intended to limit the implementation of the invention. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively describe all possible implementations. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for diagnosing open-circuit faults in a single-phase four-quadrant rectifier IGBT under multiple operating conditions, characterized in that, Includes the following steps: S1: Obtain historical data of AC side voltage, AC side current, and DC side voltage of a single-phase four-quadrant rectifier over several complete operating cycles; S2: Based on the historical data described in S1, obtain the total harmonic distortion rate threshold, the DC side voltage threshold, and the first AC side current threshold. S3: Construct an IGBT open circuit fault location and identification model, and train the IGBT open circuit fault location and identification model based on historical data to obtain a trained IGBT open circuit fault location and identification model. S4: After the AC side voltage crosses zero, the AC side current of the single-phase four-quadrant rectifier is collected in real time, the total harmonic distortion rate of the AC side current in a complete working cycle is calculated, and step S5 is executed. S5: If the total harmonic distortion rate is greater than the set total harmonic distortion rate threshold, an IGBT open circuit fault occurs. At the beginning of the next cycle, the fault location stage is entered and step S6 is executed; otherwise, step S7 is executed. S6: Real-time acquisition of DC side voltage and AC side current of the single-phase four-quadrant rectifier under test in this cycle, and calculation of the average value A of DC side voltage and the average value B of AC side current in this cycle, and execution of step S8. S7: Collect the AC side current of the single-phase four-quadrant rectifier in the next complete working cycle, calculate the total harmonic distortion rate of the AC side current, and return to S5. S8: If the average value B is less than the first threshold of the AC side current, execute S9; otherwise, execute S10. S9: If the average value A is greater than the DC side voltage threshold, the single-phase four-quadrant rectifier IGBT will experience an inverter operation fault; otherwise, proceed to the single-phase four-quadrant rectifier IGBT double tube fault judgment process. S10: Extract the data segments corresponding to the AC side current and DC side voltage within this cycle, and obtain the feature vector after preprocessing the data segments; The feature vector is input into the trained IGBT open circuit fault location and identification model, and the IGBT open circuit fault location and identification model is used to diagnose IGBT faults in a single-phase four-quadrant rectifier.

2. The method for diagnosing open-circuit faults of IGBTs in single-phase four-quadrant rectifiers under multiple operating conditions as described in claim 1, characterized in that, The process of obtaining the total harmonic distortion rate threshold is as follows: Set a sliding window with a fixed length and step size for data interception. Take the zero-crossing point of the AC side voltage as the starting point for data interception. The AC side current is intercepted based on the sliding window, and linear interpolation is used to supplement the intercepted AC side current. Using the Fast Fourier Transform (FFT) method, based on the intercepted AC side current, the total harmonic distortion (THD) values ​​within different complete duty cycles are calculated. The expression for calculating the THD is as follows: In the formula, This indicates the calculation of total harmonic distortion (THD). This represents the effective value of the Kth harmonic current. This represents the effective value of the fundamental current, and n represents the highest harmonic order. The total harmonic distortion rate (THD) values ​​of a single-phase four-quadrant rectifier with and without IGBT failure are compared to obtain the THD threshold.

3. The method for diagnosing open-circuit faults of IGBTs in single-phase four-quadrant rectifiers under multiple operating conditions as described in claim 1, characterized in that, Set a sliding window with a fixed length and step size for data interception. Take the AC side voltage zero crossing point as the starting point for data interception. Based on the sliding window, intercept the DC side voltage within several complete working cycles. Based on the intercepted DC side voltage, calculate the average DC side voltage of the data segment within the sliding window. Compare the average DC side voltage of the single-phase four-quadrant rectifier IGBT under inverter operation fault and rectifier dual-tube fault to obtain the DC side voltage threshold. The AC current is captured within several complete operating cycles using a sliding window. Based on the captured AC current, the average AC current of the data segment within the sliding window is calculated. The average AC current of the single-phase four-quadrant rectifier IGBT under rectification conditions for TIT4 and T2T3 faults is compared with the average AC current of faults under other rectification conditions to obtain a first threshold for AC current. The average AC current of the single-phase four-quadrant rectifier IGBT under rectification conditions for TIT4 and T2T3 faults is compared with the average AC current of the single-phase four-quadrant rectifier IGBT under inverter conditions for T1T4 and T2T3 faults to obtain a second threshold for AC current.

4. The method for diagnosing open-circuit faults of IGBTs in single-phase four-quadrant rectifiers under multiple operating conditions as described in claim 1, characterized in that, The process for determining a dual-transistor fault in the rectification mode of a single-phase four-quadrant rectifier IGBT is as follows: if the average value B is less than the second threshold of the AC side current, the single-phase four-quadrant rectifier IGBT experiences a rectification mode TIT4 or T2T3 fault; otherwise, the single-phase four-quadrant rectifier IGBT experiences other faults in the inverter mode.

5. The method for diagnosing open-circuit faults of IGBTs in single-phase four-quadrant rectifiers under multiple operating conditions according to claim 1, characterized in that, The IGBT open-circuit fault location and identification model includes: an input layer, a hidden layer, and an output layer; The input layer of the IGBT open-circuit fault location and identification model receives feature vectors; the output of the input layer is input to the hidden layer, in which the number of hidden layer nodes is set, the input weights and biases of the hidden layer are randomly initialized, the parameter hidden layer performs weighted summation on the input feature vectors, and performs nonlinear transformation through an activation function; the output layer outputs the IGBT fault diagnosis results of the single-phase four-quadrant rectifier. The operation expression for the hidden layer is as follows: In the formula, Represents the eigenvector. Represents the hidden layer matrix. This represents the output of the hidden layer. ω Indicates the input weights of the hidden layer. Indicates the bias of the hidden layer. This represents the input weights of the hidden layer.

6. The method for diagnosing open-circuit faults of IGBTs in single-phase four-quadrant rectifiers under multiple operating conditions according to claim 1, characterized in that, The process of training the IGBT open-circuit fault location and identification model based on historical data is as follows: S301: Extract the data segments corresponding to AC side current and DC side voltage, and construct historical feature vectors; S302: Construct a dataset from historical feature vectors and divide the dataset into a training set and a test set; S303: Initialize the number of hidden nodes in the IGBT open-circuit fault location and identification model; randomly generate the weights of the hidden layer nodes. and bias b ; S304: Input the historical feature vectors of the training set into the IGBT open-circuit fault location and recognition model to obtain the fault detection results and derive the output weights. ; S305: Based on the derived output weights The trained IGBT open-circuit fault location and identification model is obtained. S306: Input the test set into the trained IGBT open circuit fault location and identification model to verify the performance of the trained IGBT open circuit fault location and identification model.

7. The method for diagnosing open-circuit faults of IGBTs in single-phase four-quadrant rectifiers under multiple operating conditions according to claim 1, characterized in that, The process of extracting the data segments corresponding to the AC side current and DC side voltage within the current cycle is as follows: Set a sliding window with length S and step size S for data extraction, take the zero-crossing point of the AC side voltage as the starting point for data extraction, and perform sliding extraction of AC side current and DC side voltage based on the sliding window of length S to obtain AC side current and DC side voltage data segments of length S.

8. The method for diagnosing open-circuit faults of IGBTs in single-phase four-quadrant rectifiers under multiple operating conditions as described in claim 7, characterized in that, The preprocessing includes: normalizing the AC side current and DC side voltage data segments respectively, and concatenating them into a feature vector; The expression for the per-unit processing is: In the formula, The per-unit value representing the AC side current. Indicates the alternating current. Indicates the reference value of the AC side current. Indicates the equivalent resistance of the load. Indicates the AC side voltage. The per-unit value representing the DC-side voltage. Indicates the DC side voltage. Indicates the reference value of the DC side voltage; The expression for the feature vector is: X i =[ ] In the formula, X i This represents the eigenvector.

9. The method for diagnosing open-circuit faults of IGBTs in single-phase four-quadrant rectifiers under multiple operating conditions according to claim 1, characterized in that, A single-phase four-quadrant rectifier model was built on the simulation platform to simulate the operating conditions of IGBTs under rectification and inverter conditions, including single and double tube open-circuit faults and no faults. The AC side voltage, AC side current and DC side voltage were continuously collected over several complete working cycles. The load resistance value of the single-phase four-quadrant rectifier was changed to collect historical data of open-circuit faults under different loads.

10. An electronic device, characterized in that, The system includes a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the multi-condition single-phase four-quadrant rectifier IGBT open-circuit fault diagnosis program, it implements the steps of the multi-condition single-phase four-quadrant rectifier IGBT open-circuit fault diagnosis method as described in any one of claims 1-9.

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