A method for diagnosing a turn-to-turn short circuit fault of a main motor excitation winding of a multi-stage starter generator

Abstract

The application discloses a kind of multi-stage starting generator main motor field winding interturn short circuit fault diagnosis method, this method makes full use of the transferability of the fault characteristics brought by multi-stage motor structure, collects easily measured field exciter stator current signal to carry out fault diagnosis, uses square sum demodulation method and signal processing method to process the current signal, and peels out the characteristic index representing the fault state of main motor rotor side, finally by comparing the characteristic index with the preset fault threshold, realize the online identification of multi-stage motor main motor field winding interturn short circuit fault.The application does not need invasive means and algorithm is simple.

Description

Technical Field

[0001] This invention belongs to the field of motor system fault diagnosis technology, specifically relating to a method for diagnosing inter-turn short circuit faults in the excitation winding of a multi-stage starter generator, and more particularly to a non-invasive diagnostic method for diagnosing inter-turn short circuit faults in the excitation winding of the main motor using the three-phase current of the exciter stator. Background Technology

[0002] Traditional aircraft employ multiple energy systems, which directly leads to a bulky internal structure and complex engine accessories, resulting in high failure rates and poor reliability. To optimize traditional energy management systems, more-electric aircraft technology emerged. Currently, integrated starter / generator technology has become one of the key technologies in the field of more-electric aircraft. Multistage starter-generators offer advantages such as high reliability, low maintenance costs, and simple power generation technology, making them widely used in integrated starter / generator systems. For example... Figure 1 As shown, a multi-stage starter generator consists of components such as an auxiliary exciter, an exciter, a rotating rectifier, and a main motor.

[0003] In multi-stage start-up / generator systems, the main motor, as the core component for starting aircraft engines and supplying power to onboard equipment, directly determines the operational stability and output power quality of the entire system. However, due to the long-term operation of the main motor rotor under harsh conditions such as high-speed rotation, high temperature, and vibration, the failure rate of the main motor excitation winding is much higher than that of other components. Therefore, fault diagnosis of the main motor excitation winding is crucial to ensure the safe and reliable operation of the system. During the start-up phase, faults in the main motor excitation winding are typically local inter-turn short-circuit faults. To prevent more serious consequences from occurring during the generation phase while faulty, the system must make an accurate diagnosis and take corresponding measures when an inter-turn short circuit occurs. If the fault occurs during the generation phase, the short-circuit circulating current and unbalanced magnetic pull will not only severely degrade the output power quality and accelerate insulation breakdown, but may also evolve into phase-to-phase or ground faults, directly threatening flight power supply safety.

[0004] Therefore, this invention is mainly for the diagnosis and identification of inter-turn short circuit faults in the excitation winding of the main motor of a multi-stage starter generator. Summary of the Invention

[0005] The specific technical problem to be solved by this invention is: when an inter-turn short circuit fault occurs in the excitation winding of the main motor of a multi-stage starter generator, non-intrusive online diagnosis of the inter-turn short circuit fault in the excitation winding of the main motor is achieved by utilizing the fault characteristic signal in the stator current of the exciter.

[0006] To achieve the objectives of this invention, the technical solution adopted is as follows:

[0007] A method for diagnosing inter-turn short-circuit faults in the excitation winding of a multi-stage starter generator includes the following steps:

[0008] S1, Signal Acquisition;

[0009] Acquire the three-phase current signal of the exciter stator and the real-time speed signal of the motor;

[0010] S2, signal demodulation;

[0011] A speed demodulation signal is constructed based on the three-phase current signal of the exciter stator.

[0012] S3. Feature signal extraction;

[0013] Extract the DC component and the amplitude of the fundamental component and harmonic components of the fault characteristics from the speed demodulation signal, and calculate the total amplitude of the fundamental component and harmonic components of the fault characteristics.

[0014] S4. Fault diagnosis;

[0015] The fault characteristic quantity is calculated based on the DC component and the total amplitude, and the fault characteristic quantity is compared with a preset threshold to output the fault diagnosis result.

[0016] Further, step S1 specifically includes:

[0017] First, apply a frequency of [frequency value] to the stator winding of the exciter. The three-phase AC excitation voltage is then used to acquire the three-phase stator current signal of the exciter via a current sensor. , , The real-time speed signal of the motor is obtained through a position sensor. .

[0018] Further, step S2 specifically includes:

[0019] When the fault characteristic information contained in the exciter rotor current is sensed on the exciter stator side, the motor speed modulates the spectrum of the characteristic signal. The three-phase current signal of the exciter stator is processed using the sum-of-squares demodulation method to obtain the speed demodulated signal S, as shown in the following formula:

[0020] .

[0021] Furthermore, step S3 specifically includes:

[0022] 3.1 Calculate the fundamental frequency of the exciter stator current fault characteristic signal when there is an inter-turn short circuit fault in the main motor excitation winding. , Where n is the number of parallel branches per phase of the main motor stator winding. This refers to the generator speed;

[0023] Simultaneously calculate the fault characteristic harmonic frequencies , , where k is a positive integer, ranging from 1 to 5;

[0024] 3.2. The speed demodulation signal S is filtered or transformed using signal processing methods to separate and extract the DC component D, the fundamental component of the fault characteristics, and the amplitudes of its second to fifth harmonic components. ;

[0025] 3.3 Calculate the total amplitude M of the fundamental component and its second to fifth harmonic components characteristic of the fault. .

[0026] Further, step S4 specifically includes:

[0027] 4.1 Introducing Fault Characteristic Quantities The formula for calculating fault characteristic quantities is:

[0028] ;

[0029] 4.2. The obtained fault characteristic quantities Compared with the preset percentage fault threshold Perform a comparison;

[0030] like If so, it is determined that a system malfunction has occurred;

[0031] like If so, the system is in a healthy state;

[0032] Based on the comparison results, a non-invasive diagnostic result for the inter-turn short circuit fault of the main motor excitation winding is output.

[0033] The technical solution of the present invention has the following beneficial technical effects:

[0034] 1. It makes full use of the transmissibility of fault characteristics brought about by the multi-stage motor structure and uses the easily measurable three-phase current signal of the exciter stator for fault diagnosis.

[0035] 2. It can achieve non-intrusive fault diagnosis of inter-turn short circuit faults in the main motor excitation winding;

[0036] 3. The data processing procedure and algorithm are simple and easy to implement online diagnosis, which helps to improve the reliability of multi-stage starting and generating systems and avoid the spread of faults. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the multi-stage starter generator structure in this invention;

[0038] Figure 2 This is a flowchart of the main motor excitation winding inter-turn short circuit fault diagnosis process proposed in this invention;

[0039] Figure 3 This refers to the three-phase current of the exciter stator under an inter-turn short-circuit fault in the main motor excitation winding in this embodiment of the invention.

[0040] Figure 4 This refers to the sum of squares of the three-phase currents of the exciter stator under an inter-turn short-circuit fault in the main motor excitation winding in this embodiment of the invention.

[0041] Figure 5 These represent the total amplitude of the fault component and the DC component in the sum of squares of the three-phase currents of the exciter stator in this embodiment of the invention. Detailed Implementation

[0042] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0043] This embodiment uses, as follows Figure 1 Taking the multi-stage starter generator shown as an example, its exciter has a three-phase excitation winding structure, the number of pole pairs of both the exciter and the main motor is 3, the motor operating speed is 2000 rpm, and the number of parallel branches per phase of the main motor stator winding is 2. Figure 2 The diagram shown is a flowchart of the inter-turn short-circuit fault diagnosis process for the main motor excitation winding proposed in this invention. The following is a description of the proposed fault diagnosis method, with specific steps included in the embodiments:

[0044] Step 1: Acquire the three-phase current of the exciter stator and the motor speed signals online, as detailed below:

[0045] First, a three-phase AC excitation voltage with a frequency of 400Hz is applied to the stator winding of the exciter. Then, the three-phase current signal of the exciter stator is acquired by a current sensor. , , The three-phase current waveform of the exciter stator is as follows: Figure 3 As shown, the real-time speed signal of the motor is obtained through a position sensor. rpm;

[0046] Step 2: Signal demodulation:

[0047] The three-phase current signal of the exciter stator is processed using the sum-of-squares demodulation method to obtain the speed demodulated signal S, i.e. The waveform of the sum of squares of the three-phase currents in the exciter stator is as follows: Figure 4 As shown;

[0048] Step 3: Feature signal extraction:

[0049] 3.1 Calculate the fundamental frequency of the exciter stator current fault characteristic signal when there is an inter-turn short circuit fault in the main motor excitation winding. In this embodiment, Hz, and simultaneously calculate the fault characteristic harmonic frequencies. Hz (k=2, 3, 4, 5);

[0050] 3.2 First, the speed demodulation signal S is filtered. A low-pass filter is used to filter out harmonics above the fifth harmonic of the fundamental frequency of the fault characteristic signal, that is, to filter out harmonic components above 1000 / 3Hz. A fast Fourier transform is then performed on the filtered speed demodulation signal S to separate and extract the DC component D. In this embodiment... ;

[0051] 3.3 Extracting the fundamental component and its second to fifth harmonic components amplitudes of the fault characteristics. In this embodiment, the fundamental component and the amplitudes of each harmonic of the fault characteristic are as follows: , , , , ;

[0052] 3.4 Calculate the total amplitude M of the fundamental component and its second to fifth harmonic components characteristic of the fault. In this embodiment, The total amplitude M of the fault component and the DC component D are as follows: Figure 5 As shown;

[0053] Step 4: Fault Diagnosis:

[0054] 4.1 Calculate fault characteristic quantities In this embodiment ;

[0055] 4.2 In this embodiment, ( The value is 10%, which is determined based on the actual application object), indicating that a system failure has occurred.

[0056] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any other way. Any modifications or equivalent changes made based on the technical essence of the present invention shall still fall within the scope of protection claimed by the present invention.

Claims

1. A method for diagnosing inter-turn short-circuit faults in the excitation winding of a multi-stage starter generator, characterized in that, Includes the following steps: Step S1, Signal Acquisition: Acquire the three-phase current signal of the exciter stator and the real-time speed signal of the motor; Step S2, Signal Demodulation: A speed demodulation signal is constructed based on the three-phase current signal of the exciter stator. Step S3, Feature signal extraction: Extract the DC component and the amplitude of the fundamental component and harmonic components of the fault characteristics from the speed demodulation signal, and calculate the total amplitude of the fundamental component and harmonic components of the fault characteristics. Step S3 specifically includes: 3.1 Calculate the fundamental frequency of the exciter stator current fault characteristic signal when there is an inter-turn short circuit fault in the main motor excitation winding. , Where n is the number of parallel branches per phase of the main motor stator winding. This is the real-time speed signal of the motor; Simultaneously calculate the harmonic frequencies of the fault characteristic signals. , , where k is a positive integer, ranging from 1 to 5; 3.

2. The speed demodulation signal is filtered or transformed using signal processing methods to separate and extract the DC component D, the fundamental component of the fault characteristics, and the amplitudes of its second to fifth harmonic components. ; 3.3 Calculate the total amplitude M of the fundamental component and its second to fifth harmonic components characteristic of the fault. ; Step S4, Fault Diagnosis: The fault characteristic quantity is calculated based on the DC component and the total amplitude, and the fault characteristic quantity is compared with a preset threshold to output the fault diagnosis result; Step S4 specifically includes: 4.1 Introducing Fault Characteristic Quantities The formula for calculating fault characteristic quantities is: ； 4.

2. The obtained fault characteristic quantities Compared with the preset percentage fault threshold Perform a comparison; like If so, it is determined that the system has malfunctioned; like If so, the system is in a healthy state; Based on the comparison results, a non-invasive diagnostic result for the inter-turn short circuit fault of the main motor excitation winding is output.

2. The method for diagnosing inter-turn short-circuit faults in the excitation winding of a multi-stage starter generator according to claim 1, characterized in that, Step S1 specifically includes: First, apply a frequency of [frequency value] to the stator winding of the exciter. The three-phase AC excitation voltage is then used to acquire the three-phase stator current signal of the exciter via a current sensor. , , The real-time speed signal of the motor is obtained through a position sensor. .

3. The method for diagnosing inter-turn short-circuit faults in the excitation winding of a multi-stage starter generator according to claim 2, characterized in that, Step S2 specifically includes: When the fault characteristic information contained in the exciter rotor current is sensed on the exciter stator side, the motor speed modulates the spectrum of the characteristic signal. The three-phase current signal of the exciter stator is processed using the sum-of-squares demodulation method to obtain the speed demodulated signal S, as shown in the following formula: 。

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