Method and system for fault diagnosis of an electrically excited generator rotary rectifier

Abstract

This invention discloses a fault diagnosis method and system for a rotating rectifier of an electrically excited generator. First, the invention estimates the three-phase current of the exciter rotor based on the stator voltage, current, and rotor position, and calculates the absolute difference of the near-zero percentage of the three-phase current and the sum of the maximum and minimum currents within one electrical cycle. Then, based on the absolute difference of the near-zero percentage of the three-phase current and the absolute ratio of the maximum and minimum currents of any phase, it determines whether the rotating rectifier has a fault and the type of fault. Finally, based on the determined fault type, the faulty diode of the rotating rectifier is located using the minimum absolute difference of the percentage and the sum of the maximum and minimum currents. This invention can achieve fault type determination and location for a single diode in the rectifier.

Description

Technical Field

[0001] This invention relates to motor fault diagnosis technology, and more particularly to a fault diagnosis method and system for an electrically excited brushless synchronous starter / generator (hereinafter referred to as an electrically excited starter / generator) rotating rectifier. Background Technology

[0002] The "dual-carbon" goal places higher demands on the development of multi / all-electric aircraft. Among these, breakthroughs are urgently needed in high-capacity, high-reliability integrated starter-generator technology. Electrically excited brushless synchronous motors have become a key research focus due to their mature power generation technology, controllable excitation, and widespread application in aviation power systems. An electrically excited starter-generator mainly consists of coaxially mounted auxiliary exciter, exciter, rotating rectifier, and main motor, etc. Figure 1 As shown. The electrically excited generator has the following operating characteristics: 1. The excitation winding of the exciter adopts a multi-phase (two-phase or three-phase) winding structure to achieve high excitation output capability; 2. It is equipped with a position sensor to provide position information for starting control.

[0003] The exciter provides excitation current to the main motor via a rotating rectifier. Therefore, the failure of the rotating rectifier is crucial to the normal starting of the aero-engine and the output of electrical energy to the grid. Due to its coaxial mounting with the main motor, the rotating rectifier experiences significant centrifugal force and thermal stress from the harsh working environment, including rotation, high temperature, and vibration, resulting in a much higher failure rate than other components. To ensure the normal operation of the system, researching online fault diagnosis methods for the rotating rectifier is of great importance. The rotating rectifier consists of six power diodes. In practical applications, most rotating rectifier failures are open-circuit or short-circuit faults of a single diode, requiring the system to make accurate diagnoses and take appropriate measures when a single diode fails. Summary of the Invention

[0004] Purpose of the invention: This invention addresses the problems existing in the prior art by providing a fault diagnosis method and system for the rotating rectifier of an electrically excited generator that can diagnose and locate faults in a single diode.

[0005] Technical solution: The fault diagnosis method for the rotating rectifier of the electrically excited generator described in this invention includes:

[0006] (1) Estimate the three-phase current of the exciter rotor based on the exciter stator voltage, current and rotor position, and calculate the absolute difference of the near-zero value of the three-phase current and the sum of the maximum and minimum values ​​of the current within one electrical cycle.

[0007] (2) Based on the absolute difference of the proportion of near-zero three-phase currents and the absolute ratio of the maximum and minimum currents of any phase currents, determine whether the rotating rectifier has a fault and the type of fault.

[0008] (3) Based on the determined fault type, the faulty diode of the rotating rectifier is located by using the minimum value of the absolute difference of the percentage and the maximum and minimum current values.

[0009] Furthermore, step (1) specifically includes:

[0010] (1.1) Measure the stator voltage, current and rotor position of the exciter, estimate the three-phase current of the exciter rotor based on the measured data, and sample to obtain the three-phase current sampling sequence;

[0011]

[0012] In the formula, L is the number of current sampling points in one electrical cycle. Given a three-phase current sampling sequence, at the current sampling time, These are the sampling points for the three-phase current sampling sequence;

[0013] (1.2) Compare each sampling point in the three-phase current sampling sequence with a preset threshold. By comparison, the number of near-zero values ​​of the three-phase current is obtained according to the following formula;

[0014] ,

[0015] In the formula, This indicates the number of near-zero values ​​of the phase current (x).

[0016] (1.3) The proportion of near-zero values ​​of the three-phase current at the current moment is calculated according to the following formula based on the number of near-zero values:

[0017]

[0018] In the formula, These represent the percentages of near-zero values ​​for phases a, b, and c, respectively.

[0019] (1.4) Based on the proportion of near-zero values, calculate the absolute difference of the proportion of near-zero values ​​of the three-phase currents using the following formula:

[0020]

[0021] In the formula, These represent the absolute differences in the proportion of near-zero values ​​of the currents in phases a, b, and c, respectively.

[0022] (1.5) Obtain the maximum and minimum values ​​of the sampling points in the three-phase current sampling sequence, and calculate the sum of the maximum and minimum values ​​of the three-phase currents according to the following formula:

[0023]

[0024] In the formula, , and These represent the maximum and minimum values ​​of the currents in phases a, b, and c, respectively. , , These represent the maximum and minimum values ​​of the currents in phases a, b, and c within one electrical cycle, respectively.

[0025] Furthermore, step (2) specifically includes:

[0026] (2.1) Obtain the absolute difference of the proportion of three-phase currents near zero. The maximum and minimum values ​​in the range are denoted as follows: and ;

[0027] (2.2) If and If the fault is found, the rotating rectifier is determined to have an open circuit fault and step (3) is executed; otherwise, step (2.3) is executed; where, The preset threshold;

[0028] (2.3) The absolute ratio of the maximum and minimum three-phase currents is calculated using the following formula based on the three-phase current values:

[0029]

[0030] This represents the ratio of the extreme values ​​of the x-phase currents to their absolute values. These represent the maximum and minimum values ​​of the phase x current within one electrical cycle, respectively.

[0031] (2.4) If or If the condition is met, then the rotating rectifier is determined to have a short circuit fault and step (3) is executed; otherwise, the rotating rectifier is determined to be in normal working condition. This is a preset threshold.

[0032] Furthermore, step (3) specifically includes:

[0033] (3.1) If the fault type determined in step (2) is an open circuit fault, then obtain the minimum value of the absolute difference in proportion. The corresponding current phase x is determined, and the bridge arm connected to the x-phase winding is identified as the faulty bridge arm. Step (3.3) is then executed.

[0034] (3.2) If the fault type determined in step (2) is a short circuit fault, then determine whether the following conditions are met. If so, then determine whether it is true or false. The bridge arm connected to the phase winding is the faulty bridge arm; proceed to step (3.3); where, This represents the maximum and minimum values ​​of the phase current. ;

[0035] (3.3) If If so, it is determined that the diode located on the upper bridge arm of the faulty bridge arm is faulty; if If the diode on the lower bridge arm of the faulty bridge arm is found to be faulty, then the faulty bridge arm is determined to be faulty.

[0036] Furthermore, the preset threshold , The magnitude of the three-phase current composite vector is the average value over one electrical cycle.

[0037] The fault diagnosis system for the rotating rectifier of the electrically excited generator of the present invention includes:

[0038] The data processing module is used to estimate the three-phase current of the exciter rotor based on the exciter stator voltage, current and rotor position, and to calculate the absolute difference of the near-zero value ratio of the three-phase current and the sum of the extreme current values ​​within one electrical cycle.

[0039] The fault diagnosis module is used to determine whether the rotating rectifier has a fault and the type of fault based on the absolute difference of the proportion of near-zero three-phase currents and the absolute ratio of the maximum and minimum currents of any phase currents.

[0040] The fault location module is used to locate the faulty diode of the rotating rectifier by using the minimum value of the absolute difference of the percentage and the sum of the maximum and minimum current values ​​based on the determined fault type.

[0041] Furthermore, the data processing module specifically includes:

[0042] The measurement unit is used to measure the stator voltage, current, and rotor position of the exciter.

[0043] The current estimation unit is used to estimate the three-phase current of the exciter rotor based on the measured data;

[0044] The current sampling unit is used to sample the three-phase current to obtain a three-phase current sampling sequence;

[0045]

[0046] In the formula, L is the number of current sampling points in one electrical cycle. Given a three-phase current sampling sequence, at the current sampling time, These are the sampling points for the three-phase current sampling sequence;

[0047] The near-zero value calculation unit is used to compare each sampling point in the three-phase current sampling sequence with a preset threshold. By comparison, the number of near-zero values ​​of the three-phase current is obtained according to the following formula;

[0048] ,

[0049] In the formula, This indicates the number of near-zero values ​​of the phase current (x).

[0050] The near-zero value proportion calculation unit is used to calculate the near-zero value proportion of the three-phase current at the current moment according to the following formula based on the number of near-zero values:

[0051]

[0052] In the formula, These represent the percentages of near-zero values ​​for phases a, b, and c, respectively.

[0053] The near-zero value percentage absolute difference calculation unit is used to calculate the near-zero value percentage absolute difference of the three-phase currents according to the following formula:

[0054]

[0055] In the formula, These represent the absolute differences in the proportion of near-zero values ​​of the currents in phases a, b, and c, respectively.

[0056] The extreme value and maximum value calculation unit is used to obtain the maximum and minimum values ​​of the sampling points in the three-phase current sampling sequence, and calculate the extreme value and maximum value of the three-phase current according to the following formula:

[0057]

[0058] In the formula, , and These represent the maximum and minimum values ​​of the currents in phases a, b, and c, respectively. , , These represent the maximum and minimum values ​​of the currents in phases a, b, and c within one electrical cycle, respectively.

[0059] Furthermore, the fault diagnosis module specifically includes:

[0060] The extreme value acquisition unit is used to obtain the absolute difference of the proportion of three-phase currents near zero. The maximum and minimum values ​​in the range are denoted as follows: and ;

[0061] The first judgment unit is used to determine... and When an open-circuit fault is detected in the rotating rectifier, the fault location module is executed; otherwise, the extreme current absolute ratio calculation unit is executed. The preset threshold;

[0062] The extreme current absolute ratio calculation unit is used to calculate the extreme current absolute ratio of the three-phase currents based on the three-phase current values ​​using the following formula:

[0063]

[0064] This represents the ratio of the extreme values ​​of the x-phase currents to their absolute values. These represent the maximum and minimum values ​​of the phase x current within one electrical cycle, respectively.

[0065] The second judgment unit is used to determine... or If a short circuit fault occurs in the rotating rectifier, the fault location module is executed; otherwise, the rotating rectifier is determined to be in normal operating condition. This is a preset threshold.

[0066] Furthermore, the fault location module specifically includes:

[0067] The first positioning unit is used to obtain the minimum value of the absolute difference in proportion when the fault type determined by the fault judgment module is an open circuit fault. The corresponding current phase x is determined, and the bridge arm connected to the x-phase winding is identified as the faulty bridge arm, and the third positioning unit is executed.

[0068] The second positioning unit is used to determine whether the following conditions are met when the fault type determined by the fault judgment module is a short circuit fault: If so, then determine whether it is true or false. The bridge arm connected by the phase winding is the faulty bridge arm, and the third positioning unit is executed; among which... This represents the maximum and minimum values ​​of the phase current. ;

[0069] The third positioning unit is used for... When the fault occurs, it is determined that the diode located on the upper bridge arm of the faulty bridge arm is faulty; If the condition is met, then the diode located on the lower bridge arm of the faulty bridge arm is determined to be faulty.

[0070] Furthermore, the preset threshold , The magnitude of the three-phase current composite vector is the average value over one electrical cycle.

[0071] Beneficial Effects: Compared with existing technologies, the significant advantages of this invention are: This invention uses the near-zero percentage, absolute difference, maximum and minimum current sum, and absolute ratio of maximum and minimum currents of any phase current within one fundamental electrical cycle of the exciter rotor's three-phase current as characteristic differences to determine fault types and locate faulty diodes. This method boasts high accuracy, a simple data processing procedure and algorithm, and is easy to implement online. It contributes to improving the reliability of aviation electrically excited generator systems. Attached Figure Description

[0072] Figure 1 This is a schematic diagram of the structure of an electrically excited starter / generator;

[0073] Figure 2 This is a schematic diagram of the equivalent circuit of the rotor section of an electrically excited starter / generator.

[0074] Figure 3 A flowchart illustrating the fault diagnosis method for the rotating rectifier of the electrically excited generator provided by the present invention;

[0075] Figure 4 Estimate the three-phase current for the exciter rotor;

[0076] Figure 5 The percentage of near-zero three-phase current in the exciter rotor;

[0077] Figure 6 The absolute difference in the proportion of near-zero values ​​of the three-phase current of the exciter rotor;

[0078] Figure 7 The sum of the maximum and minimum three-phase currents of the exciter rotor;

[0079] Figure 8 This represents the absolute ratio of the maximum and minimum currents in phase a of the exciter rotor. Detailed Implementation

[0080] The present invention will now be further described in conjunction with the embodiments and accompanying drawings. The present invention includes, but is not limited to, the following embodiments.

[0081] Example 1

[0082] This embodiment provides a fault diagnosis method for the rotating rectifier of an electrically excited generator. A schematic diagram of the electrically excited generator structure is shown below. Figure 1 As shown, the equivalent circuit diagram of the rotor section of the electrically excited generator is as follows: Figure 2 As shown, the exciter winding of the exciter is a three-phase winding structure. Figure 3 As shown, the specific steps included in this embodiment are as follows:

[0083] (1) Estimate the three-phase current of the exciter rotor based on the exciter stator voltage, current and rotor position, and calculate the absolute difference of the near-zero value of the three-phase current and the sum of the maximum and minimum values ​​of the current within one electrical cycle.

[0084] This step specifically includes:

[0085] (1.1) Measure the stator voltage, current and rotor position of the exciter, estimate the three-phase current of the exciter rotor based on the measured data, and sample to obtain the three-phase current sampling sequence;

[0086]

[0087] In the formula, L is the number of current sampling points in one electrical cycle. Given a three-phase current sampling sequence, at the current sampling time, These are the sampling points for the three-phase current sampling sequence.

[0088] The exciter stator voltage, current, and rotor position are measured using voltage sensors, current sensors, and position sensors, respectively, to obtain the exciter stator A-phase and B-phase voltages (…). , ), current ( , ) and rotor position The three-phase current of the exciter rotor is estimated using existing methods and denoted as... , , ,like Figure 4 As shown.

[0089] With the motor operating speed at 200 r / min, the exciter stator excitation frequency at 210 Hz, and the fundamental frequency of the exciter rotor current at 200 Hz, the upper bridge arm diode D1 (e.g., ...) connected to the a-phase winding of the exciter rotor... Figure 2 Taking a short-circuit fault as an example (as shown), the number of current sampling points within one cycle is... Based on this, a sliding window method is used to sample the three-phase current of the exciter rotor in real time within one electrical cycle and form a sampling sequence. .

[0090] (1.2) Compare each sampling point in the three-phase current sampling sequence with a preset threshold. By comparison, the number of near-zero values ​​of the three-phase current is obtained according to the following formula;

[0091] ,

[0092] In the formula, This represents the number of near-zero values ​​of the phase current (x). .

[0093] Continuing from the previous example, the average value of the composite vector amplitude of the three-phase current of the exciter rotor over one electrical cycle is obtained through real-time calculation. Then set a threshold. The sampling points in the current sampling sequence are compared with the threshold. The number of near-zero values ​​of the three-phase currents were compared and obtained as follows: , , .

[0094] (1.3) The proportion of near-zero values ​​of the three-phase current at the current moment is calculated according to the following formula based on the number of near-zero values:

[0095]

[0096] In the formula, These represent the percentages of near-zero values ​​for phases a, b, and c, respectively.

[0097] Continuing with the previous example, we can calculate... .like Figure 5 As shown.

[0098] (1.4) Based on the proportion of near-zero values, calculate the absolute difference of the proportion of near-zero values ​​of the three-phase currents using the following formula:

[0099]

[0100] In the formula, These represent the absolute differences in the proportion of near-zero values ​​of the currents in phases a, b, and c, respectively.

[0101] Continuing from the previous example, , , .like Figure 6 As shown.

[0102] (1.5) Obtain the maximum and minimum values ​​of the sampling points in the three-phase current sampling sequence, and calculate the sum of the maximum and minimum values ​​of the three-phase currents according to the following formula:

[0103]

[0104] In the formula, , and These represent the maximum and minimum values ​​of the currents in phases a, b, and c, respectively. , , These represent the maximum and minimum values ​​of the currents in phases a, b, and c within one electrical cycle, respectively.

[0105] Continuing from the previous example, we can obtain , , , , , Therefore, the maximum and minimum values ​​of the three-phase currents are respectively... , , ,like Figure 7 As shown.

[0106] (2) Based on the absolute difference of the proportion of near-zero three-phase current and the absolute ratio of the maximum and minimum current of any phase current, determine whether the rotating rectifier has a fault and the type of fault.

[0107] This step specifically includes:

[0108] (2.1) Obtain the absolute difference of the proportion of three-phase currents near zero. The maximum and minimum values ​​in the range are denoted as follows: and .

[0109] Continuing from the previous example, , .like Figure 6 As shown.

[0110] (2.2) If and If the fault is found, the rotating rectifier is determined to have an open circuit fault and step (3) is executed; otherwise, step (2.3) is executed; where, The preset threshold value is 0.2 to 0.5, and is determined according to the actual application.

[0111] Continuing from the previous example, set a threshold. After comparison and judgment, Therefore, it is determined that the rotating rectifier has not experienced an open circuit fault and is in a normal or short circuit fault state.

[0112] (2.3) The absolute ratio of the maximum and minimum three-phase currents is calculated using the following formula based on the three-phase current values:

[0113]

[0114] This represents the ratio of the extreme values ​​of the x-phase currents to their absolute values. These represent the maximum and minimum values ​​of the x-phase current within one electrical cycle, respectively.

[0115] (2.4) If or If the condition is met, then the rotating rectifier is determined to have a short circuit fault and step (3) is executed; otherwise, the rotating rectifier is determined to be in normal working condition. The preset threshold value ranges from 1.5 to 4, depending on the actual application.

[0116] Continuing from the previous example, set a threshold. Furthermore, the absolute ratio of the maximum and minimum values ​​of the rotor a-phase current is used to distinguish between normal and short-circuit fault conditions. The absolute ratio of the maximum and minimum values ​​of the rotor a-phase current is calculated and obtained. ,like Figure 8 As shown. After comparison and judgment, Therefore, it is determined that a short circuit fault has occurred in the rotating rectifier.

[0117] (3) Based on the determined fault type, the faulty diode of the rotating rectifier is located by using the minimum value of the absolute difference of the percentage and the maximum and minimum current values.

[0118] This step specifically includes:

[0119] (3.1) If the fault type determined in step (2) is an open circuit fault, then obtain the minimum value of the absolute difference in proportion. The corresponding current phase x is determined, and the bridge arm connected to the x-phase winding is identified as the faulty bridge arm. Step (3.3) is then executed.

[0120] (3.2) If the fault type determined in step (2) is a short circuit fault, then determine whether the following conditions are met. If so, then determine whether it is true or false. The bridge arm connected to the phase winding is the faulty bridge arm; proceed to step (3.3); where, This represents the maximum and minimum values ​​of the phase current. .

[0121] (3.3) If If so, it is determined that the diode located on the upper bridge arm of the faulty bridge arm is faulty; if If the fault is detected, the diode located on the lower bridge arm of the faulty bridge arm is determined to be faulty. The specific fault identification criteria are shown in Table 1.

[0122] Table 1

[0123]

[0124] Continuing from the previous example, because Based on the fault diode location rule table, the bridge arm connected to phase a winding is determined to be the faulty bridge arm, meaning that a diode connected to phase a winding has a short-circuit fault. Furthermore, due to... According to the fault diode location rule table, the diode that has a short circuit fault is the diode numbered D1, that is, diode D1 has a short circuit fault.

[0125] Example 2

[0126] This embodiment provides a fault diagnosis system for the rotating rectifier of an electrically excited generator, including:

[0127] The data processing module is used to estimate the three-phase current of the exciter rotor based on the exciter stator voltage, current and rotor position, and to calculate the absolute difference of the near-zero value ratio of the three-phase current and the sum of the extreme current values ​​within one electrical cycle.

[0128] The fault diagnosis module is used to determine whether the rotating rectifier has a fault and the type of fault based on the absolute difference of the proportion of near-zero three-phase currents and the absolute ratio of the maximum and minimum currents of any phase currents.

[0129] The fault location module is used to locate the faulty diode of the rotating rectifier by using the minimum value of the absolute difference of the percentage and the sum of the maximum and minimum current values ​​based on the determined fault type.

[0130] Furthermore, the data processing module specifically includes:

[0131] The measurement unit is used to measure the stator voltage, current, and rotor position of the exciter.

[0132] The current estimation unit is used to estimate the three-phase current of the exciter rotor based on the measured data;

[0133] The current sampling unit is used to sample the three-phase current to obtain a three-phase current sampling sequence;

[0134]

[0135] In the formula, L is the number of current sampling points in one electrical cycle. Given a three-phase current sampling sequence, at the current sampling time, These are the sampling points for the three-phase current sampling sequence;

[0136] The near-zero value calculation unit is used to compare each sampling point in the three-phase current sampling sequence with a preset threshold. By comparison, the number of near-zero values ​​of the three-phase current is obtained according to the following formula;

[0137] ,

[0138] In the formula, This indicates the number of near-zero values ​​of the phase current (x).

[0139] The near-zero value proportion calculation unit is used to calculate the near-zero value proportion of the three-phase current at the current moment according to the following formula based on the number of near-zero values:

[0140]

[0141] In the formula, These represent the percentages of near-zero values ​​for phases a, b, and c, respectively.

[0142] The near-zero value percentage absolute difference calculation unit is used to calculate the near-zero value percentage absolute difference of the three-phase currents according to the following formula:

[0143]

[0144] In the formula, These represent the absolute differences in the proportion of near-zero values ​​of the currents in phases a, b, and c, respectively.

[0145] The extreme value and maximum value calculation unit is used to obtain the maximum and minimum values ​​of the sampling points in the three-phase current sampling sequence, and calculate the extreme value and maximum value of the three-phase current according to the following formula:

[0146]

[0147] In the formula, , and These represent the maximum and minimum values ​​of the currents in phases a, b, and c, respectively. , , These represent the maximum and minimum values ​​of the currents in phases a, b, and c within one electrical cycle, respectively.

[0148] Furthermore, the fault diagnosis module specifically includes:

[0149] The extreme value acquisition unit is used to obtain the absolute difference of the proportion of three-phase currents near zero. The maximum and minimum values ​​in the range are denoted as follows: and ;

[0150] The first judgment unit is used to determine... and When an open-circuit fault is detected in the rotating rectifier, the fault location module is executed; otherwise, the extreme current absolute ratio calculation unit is executed. The preset threshold;

[0151] The extreme current absolute ratio calculation unit is used to calculate the extreme current absolute ratio of the three-phase currents based on the three-phase current values ​​using the following formula:

[0152]

[0153] This represents the ratio of the extreme values ​​of the x-phase currents to their absolute values. These represent the maximum and minimum values ​​of the phase x current within one electrical cycle, respectively.

[0154] The second judgment unit is used to determine... or If a short circuit fault occurs in the rotating rectifier, the fault location module is executed; otherwise, the rotating rectifier is determined to be in normal operating condition. This is a preset threshold.

[0155] Furthermore, the fault location module specifically includes:

[0156] The first positioning unit is used to obtain the minimum value of the absolute difference in proportion when the fault type determined by the fault judgment module is an open circuit fault. The corresponding current phase x is determined, and the bridge arm connected to the x-phase winding is identified as the faulty bridge arm, and the third positioning unit is executed.

[0157] The second positioning unit is used to determine whether the following conditions are met when the fault type determined by the fault judgment module is a short circuit fault: If so, then determine whether it is true or false. The bridge arm connected by the phase winding is the faulty bridge arm, and the third positioning unit is executed; among which... This represents the maximum and minimum values ​​of the phase current. ;

[0158] The third positioning unit is used for... When the fault occurs, it is determined that the diode located on the upper bridge arm of the faulty bridge arm is faulty; If the condition is met, then the diode located on the lower bridge arm of the faulty bridge arm is determined to be faulty.

[0159] Furthermore, the preset threshold , The magnitude of the three-phase current composite vector is the average value over one electrical cycle.

[0160] This embodiment corresponds one-to-one with the method in Embodiment 1 above. Any details not covered herein will not be elaborated upon. Please refer to the description of the method in Embodiment 1.

Claims

1. A fault diagnosis method for the rotating rectifier of an electrically excited generator, characterized in that... The method includes: (1) Estimate the three-phase current of the exciter rotor based on the exciter stator voltage, current and rotor position, and calculate the absolute difference of the near-zero value of the three-phase current and the sum of the maximum and minimum values ​​of the current within one electrical cycle. (2) Based on the absolute difference of the proportion of near-zero three-phase currents and the absolute ratio of the maximum and minimum currents of any phase currents, determine whether the rotating rectifier has a fault and the type of fault. (3) Based on the determined fault type, the faulty diode of the rotating rectifier is located by using the minimum value of the absolute difference of the proportion and the maximum and minimum current values. Step (1) specifically includes: (1.1) Measure the stator voltage, current and rotor position of the exciter, estimate the three-phase current of the exciter rotor based on the measured data, and sample to obtain the three-phase current sampling sequence; , In the formula, L is the number of current sampling points in one electrical cycle. Given a three-phase current sampling sequence, at the current sampling time, These are the sampling points for the three-phase current sampling sequence; (1.2) Compare each sampling point in the three-phase current sampling sequence with a preset threshold. By comparison, the number of near-zero values ​​of the three-phase current is obtained according to the following formula; , , In the formula, This indicates the number of near-zero values ​​of the phase current (x). (1.3) The proportion of near-zero values ​​of the three-phase current at the current moment is calculated according to the following formula based on the number of near-zero values: , In the formula, These represent the percentages of near-zero values ​​for phases a, b, and c, respectively. (1.4) Based on the proportion of near-zero values, calculate the absolute difference of the proportion of near-zero values ​​of the three-phase currents using the following formula: , In the formula, These represent the absolute differences in the proportion of near-zero values ​​of the currents in phases a, b, and c, respectively. (1.5) Obtain the maximum and minimum values ​​of the sampling points in the three-phase current sampling sequence, and calculate the sum of the maximum and minimum values ​​of the three-phase currents according to the following formula: , In the formula, , and These represent the maximum and minimum values ​​of the currents in phases a, b, and c, respectively. , , These represent the maximum and minimum values ​​of the phase currents a, b, and c within one electrical cycle, respectively. Step (2) specifically includes: (2.1) Obtain the absolute difference of the proportion of three-phase currents near zero. The maximum and minimum values ​​in the range are denoted as follows: and ; (2.2) If and If the fault is found, the rotating rectifier is determined to have an open circuit fault and step (3) is executed; otherwise, step (2.3) is executed; where, The preset threshold; (2.3) The absolute ratio of the maximum and minimum three-phase currents is calculated using the following formula based on the three-phase current values: , This represents the ratio of the extreme values ​​of the x-phase currents to their absolute values. These represent the maximum and minimum values ​​of the phase x current within one electrical cycle, respectively. (2.4) If or If the condition is met, then the rotating rectifier is determined to have a short circuit fault and step (3) is executed; otherwise, the rotating rectifier is determined to be in normal working condition. This is a preset threshold.

2. The fault diagnosis method for the rotating rectifier of an electrically excited generator according to claim 1, characterized in that: Step (3) specifically includes: (3.1) If the fault type determined in step (2) is an open circuit fault, then obtain the minimum value of the absolute difference in proportion. The corresponding current phase x is determined, and the bridge arm connected to the x-phase winding is identified as the faulty bridge arm. Step (3.3) is then executed. (3.2) If the fault type determined in step (2) is a short circuit fault, then determine whether the following conditions are met. If so, then determine whether it is true or false. The bridge arm connected to the phase winding is the faulty bridge arm; proceed to step (3.3); where, This represents the maximum and minimum values ​​of the phase current. ; (3.3) If If so, it is determined that the diode located on the upper bridge arm of the faulty bridge arm is faulty; if If the diode on the lower bridge arm of the faulty bridge arm is found to be faulty, then the faulty bridge arm is determined to be faulty.

3. The fault diagnosis method for the rotating rectifier of an electrically excited generator according to claim 1, characterized in that: The preset threshold , The magnitude of the three-phase current composite vector is the average value over one electrical cycle.

4. A fault diagnosis system for a rotating rectifier of an electrically excited generator, characterized in that... The system includes: The data processing module is used to estimate the three-phase current of the exciter rotor based on the exciter stator voltage, current and rotor position, and to calculate the absolute difference of the near-zero value ratio of the three-phase current and the sum of the extreme current values ​​within one electrical cycle. The fault diagnosis module is used to determine whether the rotating rectifier has a fault and the type of fault based on the absolute difference of the proportion of near-zero three-phase currents and the absolute ratio of the maximum and minimum currents of any phase currents. The fault location module is used to locate the faulty diode of the rotating rectifier by using the minimum value of the absolute difference of the percentage and the sum of the maximum and minimum current values ​​based on the determined fault type. The data processing module specifically includes: The measurement unit is used to measure the stator voltage, current, and rotor position of the exciter. The current estimation unit is used to estimate the three-phase current of the exciter rotor based on the measured data; The current sampling unit is used to sample the three-phase current to obtain a three-phase current sampling sequence; , In the formula, L is the number of current sampling points in one electrical cycle. Given a three-phase current sampling sequence, at the current sampling time, These are the sampling points for the three-phase current sampling sequence; The near-zero value calculation unit is used to compare each sampling point in the three-phase current sampling sequence with a preset threshold. By comparison, the number of near-zero values ​​of the three-phase current is obtained according to the following formula; , , In the formula, This indicates the number of near-zero values ​​of the phase current (x). The near-zero value proportion calculation unit is used to calculate the near-zero value proportion of the three-phase current at the current moment according to the following formula based on the number of near-zero values: , In the formula, These represent the percentages of near-zero values ​​for phases a, b, and c, respectively. The near-zero value percentage absolute difference calculation unit is used to calculate the near-zero value percentage absolute difference of the three-phase currents according to the following formula: , In the formula, These represent the absolute differences in the proportion of near-zero values ​​of the currents in phases a, b, and c, respectively. The extreme value and maximum value calculation unit is used to obtain the maximum and minimum values ​​of the sampling points in the three-phase current sampling sequence, and calculate the extreme value and maximum value of the three-phase current according to the following formula: , In the formula, , and These represent the maximum and minimum values ​​of the currents in phases a, b, and c, respectively. , , These represent the maximum and minimum values ​​of the phase currents a, b, and c within one electrical cycle, respectively. The fault diagnosis module specifically includes: The extreme value acquisition unit is used to obtain the absolute difference of the proportion of three-phase currents near zero. The maximum and minimum values ​​in the range are denoted as follows: and ; The first judgment unit is used to determine... and When an open-circuit fault is detected in the rotating rectifier, the fault location module is executed; otherwise, the extreme current absolute ratio calculation unit is executed. The preset threshold; The extreme current absolute ratio calculation unit is used to calculate the extreme current absolute ratio of the three-phase currents based on the three-phase current values ​​using the following formula: , This represents the ratio of the extreme values ​​of the x-phase currents to their absolute values. These represent the maximum and minimum values ​​of the phase x current within one electrical cycle, respectively. The second judgment unit is used to determine... or If a short circuit fault occurs in the rotating rectifier, the fault location module is executed; otherwise, the rotating rectifier is determined to be in normal operating condition. This is a preset threshold.

5. The fault diagnosis system for the rotating rectifier of the electrically excited generator according to claim 4, characterized in that: The fault location module specifically includes: The first positioning unit is used to obtain the minimum value of the absolute difference in proportion when the fault type determined by the fault judgment module is an open circuit fault. The corresponding current phase x is determined, and the bridge arm connected to the x-phase winding is identified as the faulty bridge arm, and the third positioning unit is executed. The second positioning unit is used to determine whether the following conditions are met when the fault type determined by the fault judgment module is a short circuit fault: If so, then determine whether it is true or false. The bridge arm connected by the phase winding is the faulty bridge arm, and the third positioning unit is executed; among which... This represents the maximum and minimum values ​​of the phase current. ; The third positioning unit is used for... When the fault occurs, it is determined that the diode located on the upper bridge arm of the faulty bridge arm is faulty; If the condition is met, then the diode located on the lower bridge arm of the faulty bridge arm is determined to be faulty.

6. The fault diagnosis system for the rotating rectifier of the electrically excited generator according to claim 4, characterized in that: The preset threshold , The magnitude of the three-phase current composite vector is the average value over one electrical cycle.

Images