Electrical fault diagnosis method for full-stage excitation system of multi-stage starter generator

Abstract

The invention relates to an electrical fault diagnosis method for a full-stage excitation system of a multi-stage starter generator, which comprises the following steps of: firstly, acquiring stator current of an exciter and calculating vector amplitude of the stator current, and then solving characteristic quantities such as an average value, a half-cycle average value, a ratio of a minimum derivative value to a maximum derivative value and the like of the vector amplitude of the stator current; the method is used for electrical fault diagnosis of the full-stage excitation system of the multi-stage starter generator. The method provided by the invention can diagnose whether the excitation system (comprising an exciter stator winding, an exciter rotor winding, a rotating rectifier and a main motor excitation winding) of the multi-stage starter generator has an electrical fault or not and the fault type on line at the static stage, the starting stage and the power generation stage of the system. The method has important significance for improving the operation reliability and the maintenance convenience of the multi-stage starting power generation system. The method provided by the invention can diagnose whether each component of the excitation system of the multistage starter generator has an electrical fault or not on line at the static stage, the starting stage and the power generation stage of the system, and judges the fault type.

Description

Technical Field

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

[0002] The aviation starter-generator integrated system integrates the engine start and aircraft power supply functions, has the advantages of small size and weight, and high integration, and is an important development trend of the power supply system of more-electric aircraft. Among them, the multi-stage brushless synchronous starter-generator system (referred to as the multi-stage starter-generator system) has become the key research object of aviation starter-generator integrated technology due to its advantages of high reliability and good power generation quality.

[0003] Figure 1 It is a typical structure of a multi-stage brushless synchronous starter generator, which is mainly composed 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 to provide DC excitation current to the main motor excitation winding. From the static stage with zero speed to the low-speed starting stage, the multi-stage brushless synchronous starter generator system uses two-phase or three-phase AC excitation. In the high-speed starting stage, AC excitation can continue to be used or switched to DC excitation. In the power generation stage, the exciter will use DC excitation. Regardless of the operating state, the multi-stage brushless synchronous starter generator system needs to use the exciter and the rotating rectifier to provide excitation current for the main motor. Therefore, conducting electrical fault diagnosis research on the excitation system of the full stage of starting and generating is of great significance to improving the reliability and maintainability of the system.

[0004] The excitation system of the multi-stage starter generator system mainly includes the exciter stator winding, the exciter rotor winding, the rotating rectifier and the main motor excitation winding. The fault types of these components can be divided into open circuit faults and short circuit faults. In order to improve the reliability of the operation of the starter generator system, it is necessary to monitor the health status of the excitation system in real time, that is, to diagnose whether the exciter stator winding, the exciter rotor winding, the rotating rectifier and the main motor excitation winding have electrical faults in real time during the entire operation stage (including the static stage, the starting stage, and the power generation stage). This is called electrical fault diagnosis of the full-stage excitation system of the multi-stage starter generator.

[0005] When conducting electrical fault diagnosis of 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 type is an open circuit fault or a short circuit fault, so as to facilitate taking appropriate measures after the fault. At present, most of the electrical fault diagnosis methods for multi-stage starter generator systems perform separate fault diagnosis on the exciter rotor winding or rotating rectifier at a certain operating stage, and there are few methods that can achieve 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 power generation 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 main technical problems to be solved by the present invention are: online diagnosing 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 power generation stage, and judging 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 power generation stage of the starting power generation system; wherein the static stage means that the starting generator speed 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, AC first and then DC; during 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:

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

[0012] Step 2: Calculate the average value mean of i within one period by using the 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 s1<M2, proceed to Step 3;

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

[0017] The threshold M2 is the judgment threshold for the short - circuit fault of 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 thresholds P1 and P2, conduct the fault diagnosis 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 the fault of the main motor excitation winding;

[0024] The P2 is the judgment threshold for the situation where the excitation system has 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 and calculate the characteristic quantity s2 Calculate according to the comparison of s2 with the thresholds P3 and P4, conduct the fault diagnosis of the exciter rotor winding and the rotating rectifier, and judge the fault type:

[0026]

[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 distinguishing the fault of the exciter rotor winding or the open - circuit fault of the rotating rectifier;

[0031] The P4 is the judgment threshold for distinguishing the open - circuit fault or short - circuit fault of 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 period max and the minimum value d min , and calculate the absolute value of the ratio of the minimum and maximum derivative values

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

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

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

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

[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 according to the characteristic quantities obtained in steps 1 to 5, including identifying the fault component and judging the fault type, is shown in Table 1:

[0039] Table 1: Electrical fault diagnosis criterion table of the excitation system

[0040]

[0041] The value of the judgment threshold M1 for the exciter stator winding having an open - circuit fault is 0 < M1 ≤ 4.

[0042] The value of the judgment threshold M2 for the exciter stator winding having a short - circuit fault is n times the amplitude of the stator current vector when the exciter is healthy, where n = 4 - 8.

[0043] The value of the judgment threshold P1 for the main motor excitation winding having a fault is 0 < P1 ≤ 2.

[0044] The value of the judgment threshold P2 for the excitation system having no fault is 4 < P2 ≤ 10.

[0045] The value of the judgment threshold P3 for judging whether the exciter rotor winding has a fault or the rotating rectifier has an open - circuit fault is 0 < P3 ≤ 2.

[0046] 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 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 is composed of 6 diodes, the upper tube of phase A is marked as D1, the lower tube is marked as D4, the upper tube of phase B is marked as D3, 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.

[0049] Beneficial Effects

[0050] The present invention proposes a method for diagnosing electrical faults in a full-stage excitation system of a multi-stage starter generator. The method first collects the stator current of the exciter and calculates its vector amplitude, and then obtains the average value, half-cycle average value, ratio of the minimum and maximum derivative values ​​and other characteristic quantities of the stator current vector amplitude for the full-stage excitation system electrical fault diagnosis of the multi-stage starter generator. The proposed method can diagnose online whether an electrical fault occurs in the excitation system of the multi-stage starter generator (including the stator winding of the exciter, the rotor winding of the exciter, the rotating rectifier and the excitation winding of the main motor) during the system static stage, starting stage and power generation stage, and the type of fault. The method is of great significance to improving the operating reliability and maintenance convenience of the multi-stage starter generator system.

[0051] The proposed method can diagnose whether electrical faults occur in the components of the multi-stage starter generator excitation system online during the system static stage, starting stage and power generation stage, and determine the fault type. The proposed method does not depend on the exciter parameters and can improve the operating reliability and maintenance convenience of the multi-stage starter generator system. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 :Schematic diagram of 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 by the present invention

[0055] Figure 4 :Block diagram of the full-stage electrical fault diagnosis method for the excitation system proposed by the present 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, and 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 under AC excitation mode, the characteristic quantity mean of working condition 3 s1 ,s1,s2,d min / max

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

[0060] Fig. 9 : In this embodiment, the upper tube (D3) of phase B of the rotating rectifier is short-circuited under the DC excitation mode, and 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 the accompanying drawings:

[0062] Figure 3 The present invention provides a method for diagnosing electrical faults in a full-stage excitation system; Figure 4 The block diagram of the electrical fault diagnosis method of the full-stage excitation system proposed by the present invention is shown in FIG. The present invention is further described below in conjunction with the accompanying drawings and embodiments, and the present invention includes but is 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, 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 as follows: 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) During the system startup phase, AC excitation is used. The motor speed is 100 r / min, the excitation voltage of the exciter stator is 200 V, the frequency is 210 Hz, the exciter rotor current frequency is 200 Hz, and the sampling frequency is 100 kHz. The number of sampling points in one current cycle 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 current cycle is

[0067] In the stationary stage, the excitation system is healthy (operating condition 1) as an example; in the AC excitation mode, the stator winding of the exciter is open (operating condition 2) and the excitation winding of the main motor is short-circuited (operating condition 3) as an example; in the DC excitation mode, the exciter rotor winding A phase is open (operating condition 4) and the rotating rectifier B phase upper tube (D3) is short-circuited (operating condition 5) as an example to illustrate the proposed electrical fault diagnosis method. 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 Conduct electrical fault diagnosis of the stator winding of the exciter and determine the fault type. The threshold M1 is 2 and the threshold M2 is 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 an open circuit fault occurs in the stator winding of the exciter.

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

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

[0074] 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 according to s1, the threshold value P1 is 0.5, and the threshold value P2 is 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 judged that the main motor excitation winding is faulty.

[0078] Working 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 according to 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 proceed to step 5.

[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 maximum derivative values 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 judged that the exciter rotor winding has an open circuit fault.

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 can adopt various excitation methods such as full-process AC excitation, AC first and then DC; 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 The average value of 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 open circuit faults in the stator winding of the exciter. The threshold M2 is the judgment threshold for short circuit faults 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 determined: (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 faults in the main motor excitation winding. The P2 is the judgment threshold for the situation where the excitation system has no fault. Step 4: Calculate i within half a cycle using the sliding window mode according to the exciter rotor current frequency s The average value of 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 whether the exciter rotor winding has a fault or the rotating rectifier has an open circuit fault. The P4 is the judgment threshold for judging whether the rotating rectifier has an open circuit fault or a short circuit fault. Step 5: Calculate i s The derivative of p(i s ), calculate p(i s ) has the maximum value d max With the minimum value d min , and calculate the absolute value of the ratio of the minimum to maximum derivative values According to d min / max And thresholds are used to determine 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 whether the exciter rotor winding has an open circuit fault or a short circuit fault. Based on steps 1 to 5, the multi-stage electrical fault diagnosis criterion for the starting generator excitation system is carried out, and the faulty components are identified and the fault types are judged.

2. The method for diagnosing electrical faults in a full-stage excitation system of a multi-stage starter generator according to claim 1 is characterized in that: The stator current of the exciter is collected by using 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 is characterized in that: The value of the judgment threshold M1 for open circuit faults 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 is characterized in that: The value of the judgment threshold M2 for short circuit faults 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 is characterized in that: The value of the judgment threshold P1 for faults 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 is characterized in that: The value of the judgment threshold P2 for the situation 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 is characterized in that: The value of the judgment threshold P3 for judging whether the exciter rotor winding has a fault or the rotating rectifier has an open circuit fault is 0 < P3 ≤ 2.

8. The method for diagnosing electrical faults in a full-stage excitation system of a multi-stage starter generator according to claim 1 is characterized in that: 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.

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: 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.

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 is composed of 6 diodes, the upper tube of the A phase is marked as D1, and the lower tube is marked as D4, the upper tube of the B phase is marked as D3, and the lower tube is marked as D6, and the upper tube of the C phase is marked as D5, and the lower tube is marked as D2.

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