A method for diagnosing electrical faults in the full-stage excitation system of a multi-stage starter generator

Abstract

The present invention relates to a method for diagnosing electrical faults in the full-stage excitation system of a multi-stage starter generator. The method first collects the exciter stator current and calculates its vector amplitude. Feature quantities such as the average value, half-cycle average value, and the ratio of the minimum to maximum derivative values ​​of the stator current vector amplitude are then calculated for use in diagnosing electrical faults in the full-stage excitation system of the multi-stage starter generator. The proposed method can online diagnose whether an electrical fault has occurred in the multi-stage starter generator excitation system (including the exciter stator winding, exciter rotor winding, rotating rectifier, and main motor excitation winding) during the system's quiescent, starting, and generating phases, as well as the type of fault. This method is of great significance for improving the operational reliability and maintenance convenience of the multi-stage starter generator system. The proposed method can online diagnose whether an electrical fault has occurred in various components of the multi-stage starter generator excitation system during the system's quiescent, starting, and generating phases, and determine the type of fault.

Description

Technical Field

[0001] The invention belongs to the technical field of motor fault diagnosis, and relates to a method for diagnosing electrical faults of a full-stage excitation system of a multi-stage starter generator. Background Art

[0002] Integrated aviation starter-generator systems combine engine starting and aircraft power supply functions, offering advantages such as compact size, weight, and high integration. They are a key development trend in power systems for more-electric aircraft. Multi-stage brushless synchronous starter-generator systems (MSGSs) have become a key research focus for integrated aviation starter-generator technologies due to their high reliability and excellent power generation quality.

[0003] Figure 1 This is a typical structure of a multi-stage brushless synchronous starter generator, consisting primarily of a coaxially mounted permanent magnet auxiliary exciter, an exciter, a rotating rectifier, and a main motor. The exciter rotor winding is connected to the rotating rectifier, providing DC excitation current to the main motor's excitation winding. From the zero-speed standstill phase to the low-speed starting phase, the exciter uses two-phase or three-phase AC excitation. During the high-speed starting phase, AC excitation can continue or switch to DC excitation. During the generating phase, the exciter uses DC excitation. Regardless of operating state, the multi-stage brushless synchronous starter generator system requires the exciter and rotating rectifier to provide excitation current to the main motor. Therefore, research on electrical fault diagnosis of the excitation system during all stages of starting and generating is crucial for improving system reliability and maintainability.

[0004] The excitation system of a multi-stage starter-generator system primarily consists of the exciter stator winding, exciter rotor winding, rotating rectifier, and main motor excitation winding. Faults in these components can be categorized as open-circuit or short-circuit. To improve the reliability of the starter-generator system, real-time monitoring of the excitation system's health is essential. This involves diagnosing electrical faults in the exciter stator winding, exciter rotor winding, rotating rectifier, and main motor excitation winding throughout all operating phases (including stationary, starting, and generating). This is known as full-stage excitation system electrical fault diagnosis for a multi-stage starter-generator.

[0005] When conducting electrical fault diagnosis for the full-stage excitation system of a multi-stage starter generator, in addition to determining the faulty component, it is also necessary to diagnose whether the fault is an open circuit or a short circuit, so that appropriate measures can be taken after the fault occurs. Currently, most electrical fault diagnosis methods for multi-stage starter generator systems focus on individual faults of the exciter rotor winding or rotating rectifier at a specific operating stage. Few methods can perform electrical fault diagnosis for the entire excitation system at all stages.

[0006] The present invention proposes an electrical fault diagnosis method for a multi-stage starting generator full-stage excitation system based on the characteristics of the exciter stator current. The proposed method can online diagnose whether electrical faults occur in the multi-stage starting generator excitation system (including the exciter stator winding, exciter rotor winding, rotating rectifier, and main motor excitation winding) and the fault types during the static stage, starting stage, and generating stage of the system. Summary of the Invention

[0007] Technical Problems to be Solved

[0008] In order to avoid the deficiencies of the prior art, the present invention proposes an electrical fault diagnosis method for a multi-stage starting generator full-stage excitation system. For the electrical fault diagnosis of the multi-stage starting generator full-stage excitation system, the technical problems to be solved by the present invention are mainly: online diagnose whether electrical faults occur in the multi-stage starting generator excitation system (including the exciter rotor winding, exciter stator winding, rotating rectifier, and main motor excitation winding) during the static stage, starting stage, and generating stage, and determine the fault type (open circuit fault or short circuit fault).

[0009] Technical Solution

[0010] An electrical fault diagnosis method for a multi-stage starting generator full-stage excitation system, characterized in that the full stage includes the static stage, starting stage, and generating stage of the starting and generating system; where the static stage means that the speed of the starting generator is zero and the exciter adopts a polyphase AC excitation method; during the starting stage, the exciter can adopt various excitation methods such as full-process AC excitation, first AC then DC, etc.; during the generating stage, the exciter adopts a DC excitation method. The electrical faults include open circuit faults and short circuit faults; the fault diagnosis steps are as follows:

[0011] Step 1: Collect the exciter stator current, and record the amplitude of the stator current vector as i

[0012] ;

[0012] Step 2: Calculate the average value mean of i within one cycle using a sliding window mode according to the exciter rotor current frequency s of, and judge the fault type of the exciter by comparing the average value mean s1 with the threshold M1 and the threshold M2: s1

[0013] (1) If mean s1 < M1, it is judged that an open circuit fault occurs in the exciter stator winding;

[0014] (2) If mean s1 ≥ M2, it is judged that a short circuit fault occurs in the exciter stator winding;

[0015] ]](3) If M1 ≤ mean (3) If M1 ≤ mean <00<M2, proceed to step 3;

[0016] The threshold value M1 is the judgment threshold for an open - circuit fault in the exciter stator winding;

[0017] The threshold value M2 is the judgment threshold for a short - circuit fault in the exciter stator winding;

[0018] Step 3: Calculate mean s1 and i s 's characteristic quantity where k T is the number of sampling points in one period;

[0019] Based on the comparison of the characteristic quantity s1 with the threshold values P1 and P2, diagnose the fault of the main motor excitation winding:

[0020] (1) If P1 ≤ s1 < P2, it is judged that the excitation system has no fault, that is, the excitation system is healthy;

[0021] (2) If s1 < P1, it is judged that the main motor excitation winding has a fault;

[0022] (3) If s1 ≥ P2, proceed to step 4;

[0023] The P1 is the judgment threshold for a fault in the main motor excitation winding;

[0024] The P2 is the judgment threshold for the excitation system having no fault;

[0025] Step 4: Calculate the average value mean of i within half a period in a sliding window mode according to the exciter rotor current frequency s , calculate the characteristic quantity s2 [[ID= forty - two]] and

[0026] Based on the comparison of s2 with the threshold values P3 and P4, diagnose the faults of the exciter rotor winding and the rotating rectifier, and judge the fault type:

[0027] (1) If P3 ≤ s2 < P4, it is judged that the rotating rectifier has an open - circuit fault;

[0028] (2) If s2 ≥ P4, it is judged that the rotating rectifier has a short - circuit fault;

[0029] (3) When s2 < P3, it is judged that the exciter rotor winding has a fault, and proceed to step 5;

[0030] The P3 is the judgment threshold for judging a fault in the exciter rotor winding or an open - circuit fault in the rotating rectifier;

[0031] The P4 is the judgment threshold for judging an open - circuit fault or a short - circuit fault in the rotating rectifier;

[0032] Step 5: Calculate i s The derivative of is p(i s ), calculate the maximum value d of p(i s ) within one rotor current cycle max and the minimum value d min , and calculate the absolute value of the ratio of the minimum to the maximum derivative value

[0033] Based on d min / max and the threshold value, judge the type of fault in the exciter rotor winding:

[0034] (1) When d min / max < D1, it is judged that a short - circuit fault has occurred in the exciter rotor winding;

[0035] (2) If d min / max ≥D1, it is judged that an open - circuit fault has occurred in the exciter rotor winding;

[0036] The D1 is the judgment threshold for judging an open - circuit fault or a short - circuit fault in the exciter rotor winding;

[0037] The multi - stage starting - generator excitation system electrical fault diagnosis criterion based on steps 1 to 5, as well as identifying the fault component and judging the fault type.

[0038] The multi - stage starting - generator excitation system electrical fault diagnosis criterion based on the characteristic quantities obtained in steps 1 to 5, including identifying the fault component and judging the fault type, is shown in Table 1:<​​​​​​​​​​​​​​​​​​​​​​The value of the judgment threshold P4 for judging whether the rotating rectifier has an open circuit fault or a short circuit fault is 6 <P4≤10。

[0047] The value of the judgment threshold D1 for judging whether the exciter rotor winding has an open circuit fault or a short circuit fault is 1.5 <D1≤3。

[0048] The excitation system includes the exciter rotor winding, the exciter stator winding, a rotating rectifier, and the main motor excitation winding. The exciter rotor winding includes three-phase windings (A, B, and C), while the exciter stator excitation winding is multi-phase. The rotating rectifier consists of six diodes: the upper diode of phase A is labeled D1 and the lower diode is labeled D4; the upper diode of phase B is labeled D3 and the lower diode is labeled D6; and the upper diode of phase C is labeled D5 and the lower diode is labeled D2.

[0049] Beneficial effects

[0050] This invention proposes a method for diagnosing electrical faults in the full-stage excitation system of a multi-stage starter generator. This method first collects the exciter stator current and calculates its vector amplitude. Then, characteristic quantities such as the average value, half-cycle average value, and the ratio of the minimum to maximum derivative values ​​of the stator current vector amplitude are calculated for use in diagnosing electrical faults in the full-stage excitation system of the multi-stage starter generator. This method can online diagnose the presence and type of electrical faults in the multi-stage starter generator excitation system (including the exciter stator winding, exciter rotor winding, rotating rectifier, and main motor excitation winding) during the system's stationary, starting, and generating phases. This method is of great significance for improving the operational reliability and maintenance convenience of multi-stage starter generator systems.

[0051] The proposed method can online diagnose electrical faults in various components of a multi-stage starter generator excitation system during the system's static, startup, and generating phases, and determine the fault type. The proposed method is independent of exciter parameters and can improve the operational reliability and maintenance convenience of the multi-stage starter generator system. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 :Schematic diagram of the multi-stage starter generator structure

[0053] Figure 2 :Equivalent circuit diagram of multi-stage starter generator excitation system

[0054] Figure 3 :The idea of ​​the full-stage electrical fault diagnosis method of the excitation system proposed in this invention

[0055] Figure 4 :Block diagram of the full-stage electrical fault diagnosis method for the excitation system proposed in this invention

[0056] Figure 5: In this embodiment, the excitation system does not fail during the static phase, and the characteristic quantity mean under working condition 1 is s1 ,s1,s2,d min / max

[0057] Figure 6 : In this embodiment, the stator winding of the exciter is open-circuited under AC excitation mode. The characteristic quantity mean under working condition 2 is s1 ,s1,s2,d min / max

[0058] Figure 7 : In this embodiment, the main motor excitation winding short circuit fault in AC excitation mode, the characteristic value mean of working condition 3 s1 ,s1,s2,d min / max

[0059] Figure 8 : In this embodiment, under the DC excitation mode, the exciter rotor A phase winding open circuit fault, the characteristic quantity mean under working condition 4 s1 ,s1,s2,d min / max

[0060] Figure 9 : In this embodiment, the upper tube (D3) of phase B of the rotating rectifier is short-circuited under the DC excitation mode. The characteristic quantity mean under working condition 5 is s1 ,s1,s2,d min / max DETAILED DESCRIPTION

[0061] The present invention will now be further described with reference to the embodiments and accompanying drawings:

[0062] Figure 3 This is the idea of ​​the full-stage excitation system electrical fault diagnosis method proposed by the present invention; Figure 4 The present invention is further described below with reference to the accompanying drawings and embodiments, which include but are not limited to the following embodiments.

[0063] In the embodiment, a simulation model of a multi-stage starter generator system is built. The multi-stage starter generator structure included in the embodiment is as follows: Figure 1 As shown in FIG, the stator excitation winding of the exciter is a two-phase winding. The equivalent circuit diagram of the multi-stage starter generator excitation system in the embodiment is shown in FIG. Figure 2 The multi-stage starter generator model is simulated in three states:

[0064] (1) The system is in the static stage, the motor speed is 0r / min, the excitation voltage of the exciter stator is 200V, and the frequency is 200Hz. At this time, the frequency of the rotor current is 200Hz, and the sampling frequency is 100kHz. The number of sampling points in one cycle of the current is

[0065] (2) The system adopts AC excitation mode in the starting stage, the motor speed is 100r / min, the excitation voltage of the exciter stator is 200V, the frequency is 210Hz, the exciter rotor current frequency is 200Hz, and the sampling frequency is 100kHz. The number of sampling points in one cycle of the current is

[0066] (3) The system adopts DC excitation mode in the power generation stage, the motor speed is 800r / min, the excitation voltage of the exciter stator is 50V DC, the exciter rotor current frequency is 80Hz, and the sampling frequency is 100kHz. The number of sampling points in one cycle of the current is

[0067] The proposed electrical fault diagnosis method is described by taking the healthy excitation system (operating condition 1) as an example in the stationary phase; the open circuit of the stator winding of the exciter (operating condition 2) and the short circuit of the excitation winding of the main motor (operating condition 3) as examples in the AC excitation mode; and the open circuit of the rotor winding A phase of the exciter (operating condition 4) and the short circuit of the upper tube (D3) of the rotating rectifier phase B (operating condition 5) as examples in the DC excitation mode. The specific steps included in the embodiment are as follows:

[0068] 1. Collect the stator current of the exciter through the sensor, denoted as i alphs 、i betas , and find the vector magnitude of the stator current,

[0069] 2. According to the exciter rotor current frequency, the sliding window mode is used to calculate the i within one cycle. s The average value, denoted as mean s1 , k T is the number of sampling points in one cycle. s1 Perform electrical fault diagnosis on the stator winding of the exciter and determine the fault type. The threshold M1 is set to 2 and the threshold M2 is set to 40. Simulation results Figure 5-Figure 9 shown.

[0070] Condition 1 (system static): mean s1 =4.7,40>mean s1 ≥2, and proceed to step 3.

[0071] Working condition 2 (AC excitation mode): mean s1 =0, mean s1 <2, determine that the stator winding of the exciter has an open circuit fault.

[0072] Working condition 3 (AC excitation mode): mean s1 =13.9,40>means1 ≥2, and proceed to step 3.

[0073] Working condition 4 (DC excitation mode): mean s1 =12.5,40>mean s1 ≥2, and proceed to step 3.

[0074] Working condition 5 (DC excitation mode): mean s1 =12.8,40>mean s1 ≥2, and proceed to step 3.

[0075] 3. According to mean s1 with i s Calculate the feature quantity s1, The electrical fault diagnosis of the main motor excitation winding is performed based on s1, the threshold P1 is set to 0.5, and the threshold P2 is set to 8.

[0076] Working condition 1 (system static): s1=4.27, 0.5≤s1<8, it is determined that there is no fault in the excitation system.

[0077] Working condition 3 (AC excitation mode): s1=0.1, s1<0.5, it is determined that the main motor excitation winding is faulty.

[0078] Operating condition 4 (DC excitation mode): s1 = 13.0, s1 ≥ 8, and proceed to step 4.

[0079] Working condition 5 (DC excitation mode): s1 = 22.2, s1 ≥ 8, and proceed to step 4.

[0080] 4. According to the exciter rotor current frequency, the sliding window mode is used to calculate the i within half a cycle. s The average value, denoted as mean s2 , According to mean s1 and mean s2 Calculate the feature quantity s2, The electrical fault diagnosis of the exciter rotor winding and the rotating rectifier is performed based on s2, and the fault type is determined. The threshold value P3 is 0.5, and the threshold value P4 is 7.

[0081] Working condition 4 (DC excitation mode): s2=0, s2<0.5, it is determined that the exciter rotor winding is faulty, and step 5 is performed.

[0082] Working condition 5 (DC excitation mode): s2=12.1, s2≥7, it is determined that a short circuit fault occurs in the rotating rectifier.

[0083] 5. Calculate i s The derivative ofs ). Calculate p(i s ) are denoted as d max and d min , and calculate the absolute value of the ratio of the minimum to the maximum derivative value According to d min / max To determine the fault type of the exciter rotor winding, the threshold D1 is set to 2.

[0084] Working condition 4 (DC excitation mode): d min / max =3.4,d min / max ≥2, it is determined that an open circuit fault has occurred in the exciter rotor winding.

Claims

1. A method for diagnosing electrical faults in a full-stage excitation system of a multi-stage starter generator, characterized in that The full stage includes the stationary stage, starting stage, and power generation stage of the starting and generating system; the stationary stage means that the speed of the starting generator is zero, and the exciter adopts a polyphase AC excitation method; in the starting stage, the exciter adopts a full-process AC excitation or an AC-then-DC excitation method; in the power generation stage, the exciter adopts a DC excitation method; the electrical faults include open-circuit faults and short-circuit faults; the fault diagnosis steps are as follows: Step 1: Collect the stator current of the exciter and record the magnitude of the stator current vector as i s ; Step 2: Calculate the i within one cycle using the sliding window mode according to the exciter rotor current frequency s mean s1 , with the mean value s1 Compare with thresholds M1 and M2 to determine the fault type of the exciter: (1) If mean s1 <M1, it is determined that an open - circuit fault has occurred in the exciter stator winding; (2) If mean s1 ≥M2, it is judged that the stator winding of the exciter has a short circuit fault; (3) If M1 ≤ mean s1 < M2, perform step 3; The threshold M1 is the judgment threshold for an open-circuit fault in the stator winding of the exciter. The threshold M2 is the judgment threshold for a short-circuit fault in the stator winding of the exciter. Step 3: Calculate mean s1 with i s The characteristic quantity where k T is the number of sampling points in one cycle; Based on the comparison of the characteristic quantity s1 with the thresholds P1 and P2, the fault diagnosis of the main motor excitation winding is judged: (1) If P1 ≤ s1 < P2, it is judged that the excitation system has no fault, that is, the excitation system is healthy. (2) If s1 < P1, it is judged that the main motor excitation winding has a fault. (3) If s1 ≥ P2, go to step 4. The P1 is the judgment threshold for a fault in the main motor excitation winding. The P2 is the judgment threshold for the case where the excitation system has no fault. Step 4: Calculate the i within half a cycle using the sliding window mode according to the exciter rotor current frequency s mean s2 , calculate the feature quantity Based on the comparison of s2 with the thresholds P3 and P4, the fault diagnosis of the exciter rotor winding and the rotating rectifier is carried out, and the fault type is judged: (1) If P3 ≤ s2 < P4, it is judged that the rotating rectifier has an open-circuit fault. (2) If s2 ≥ P4, it is judged that the rotating rectifier has a short-circuit fault. (3) When s2 < P3, it is judged that the exciter rotor winding has a fault, and go to step 5. The P3 is the judgment threshold for judging a fault in the exciter rotor winding or an open-circuit fault in the rotating rectifier. The P4 is the judgment threshold for judging an open-circuit fault or a short-circuit fault in the rotating rectifier. Step 5: Calculate i s The derivative of p(i s ), calculate p(i s ) the maximum value d max With the minimum value d min , and calculate the absolute value of the ratio of the minimum to the maximum derivative value According to d min / max And the threshold value is used to judge the fault type of the exciter rotor winding: (1) When d min / max <D1, it is determined that a short-circuit fault has occurred in the exciter rotor winding; (2) If d min / max ≥D1, it is judged that the exciter rotor winding has an open circuit fault; The D1 is the judgment threshold for judging an open-circuit fault or a short-circuit fault in the exciter rotor winding. The multi-stage starting generator excitation system electrical fault diagnosis criterion carried out according to steps 1 to 5, as well as identifying the fault components and judging the fault types.

2. The method for diagnosing electrical faults in a full-stage excitation system of a multi-stage starter generator according to claim 1, characterized in that: The stator current of the exciter is collected by a current sensor connected in series in the stator circuit of the exciter.

3. The method for diagnosing electrical faults in a full-stage excitation system of a multi-stage starter generator according to claim 1, characterized in that: The numerical value of the judgment threshold M1 for an open-circuit fault in the stator winding of the exciter is 0 < M1 ≤ 4.

4. The method for diagnosing electrical faults in a full-stage excitation system of a multi-stage starter generator according to claim 1, characterized in that: The numerical value of the judgment threshold M2 for a short-circuit fault in the stator winding of the exciter is n times the amplitude of the stator current vector when the exciter is healthy, where n = 4 - 8.

5. The method for diagnosing electrical faults in a full-stage excitation system of a multi-stage starter generator according to claim 1, characterized in that: The numerical value of the judgment threshold P1 for a fault in the main motor excitation winding is 0 < P1 ≤ 2.

6. The method for diagnosing electrical faults in a full-stage excitation system of a multi-stage starter generator according to claim 1, characterized in that: The numerical value of the judgment threshold P2 for the case where the excitation system has no fault is 4 < P2 ≤ 10.

7. The method for diagnosing electrical faults in a full-stage excitation system of a multi-stage starter generator according to claim 1, characterized in that: The numerical value of the judgment threshold P3 for judging a fault in the exciter rotor winding or an open-circuit fault in the rotating rectifier is 8. The method for diagnosing electrical faults in a full-stage excitation system of a multi-stage starter generator according to claim 1, characterized in that: ​ P4≤10。 9. The method for diagnosing electrical faults in a full-stage excitation system of a multi-stage starter generator according to claim 1, characterized in that: ​ 10. The method for diagnosing electrical faults in a full-stage excitation system of a multi-stage starter generator according to claim 1, characterized in that: The excitation system includes an exciter rotor winding, an exciter stator winding, a rotating rectifier and a main motor excitation winding; the exciter rotor winding includes three-phase windings A, B and C, and the exciter stator excitation winding is a multi-phase winding; the rotating rectifier consists of 6 diodes, the upper tube of phase A is marked as D1 and the lower tube is marked as D4, the upper tube of phase B is marked as D3 and the lower tube is marked as D6, and the upper tube of phase C is marked as D5 and the lower tube is marked as D2.

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