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### 논문리뷰_Blodt 위주.pptx

1. 1 기계적 고장에 의한 Stator Current Modulation 에 관한 조사 • Load torque under mechanical fault • Rotor speed • Rotor angle + H.O.T In steady state ->Torque oscillation 으로 일어나는 항 1.[Mechanical Load Fault Detection in Induction Motors by Stator Current Time-Frequency Analysis],2006,TIA, 270인용 Blodt (2006,2008,2009) 논문 3개
2. 2 기계적 고장에 의한 Stator Current Modulation 에 관한 조사 • Rotor MMF wave • Stator MMF wave -> no direct influence of torque oscillation + H.O.T • Airgap Magnetic Flux Density = MMF Sum X Permeance • Airgap Magnetic Flux = integration of Airgap Flux Density • Stator voltage equation Time-varying phase 질문 : PMSM에서는 어떻게 되나요? 1.[Mechanical Load Fault Detection in Induction Motors by Stator Current Time-Frequency Analysis],2006,TIA, 270인용
3. 3 기계적 고장에 의한 Stator Current Modulation 에 관한 조사 • PSD based on discrete FT • Instantaneous Frequency (IF) • Wigner Distribution (WD) : FT of a kernel Kx(τ,t) with respect to the delay variable τ . The kernel is similar to an autocorrelation function. • Spectrogram : time-frequency distribution based on the FT of the product of a sliding window h(t) with the signal 1.[Mechanical Load Fault Detection in Induction Motors by Stator Current Time-Frequency Analysis],2006,TIA, 270인용
4. 4 기계적 고장에 의한 Stator Current Modulation 에 관한 조사 2.[Models for Bearing Damage Detection in Induction Motors Using Stator Current Monitoring],2008, TIE, 536인용 , • Airgap length variation • Airgap permeance • Airgap Magnetic Flux Density = MMF Sum X Permeance Fault-related sine waves(k>1) • Airgap Magnetic Flux ->has additional term as Airgap Magnetic Flux Density I. Radial Rotor Movement (Rotor Eccentricity) 본인의 2006 논문에다 베어링 고장을 2가지 관점(Rotor Eccentricity, Load Torque Oscillation)으로 연관시킴
5. 5 기계적 고장에 의한 Stator Current Modulation 에 관한 조사 • Stator voltage equation ->has additional term as Airgap Magnetic Flux radial rotor movement due to the bearing fault results in additional frequencies in the stator current I. Radial Rotor Movement (Rotor Eccentricity) 2.[Models for Bearing Damage Detection in Induction Motors Using Stator Current Monitoring],2008, TIE, 536인용 ,
6. 6 기계적 고장에 의한 Stator Current Modulation 에 관한 조사 • Load Torque II. LoadTorque Variations each time a ball passes in a hole, mechanical resistance will appear when the ball tries to leave the hole. The consequence is a small increase of the load torque; The bearing fault-related torque variations appear at the previously mentioned characteristic vibration frequencies fc • Rotor speed • Rotor angle • Rotor MMF • Airgap Magnetic Flux Density • Stator current I1 > I2 2.[Models for Bearing Damage Detection in Induction Motors Using Stator Current Monitoring],2008, TIE, 536인용 ,
7. 7 기계적 고장에 의한 Stator Current Modulation 에 관한 조사 3. [Distinguishing Load Torque Oscillations and Eccentricity Faults in Induction Motors Using Stator Current Wigner Distributions],2009,TIA, 144인용 Mechanical Faults Load Torque Oscillations Eccentricity Faults Above both [In general, eccentricity is a sign for a mechanical problem within the electric motor, whereas load torque oscillations point to a fault that is located outside of the motor.] 이전 논문들에서 나왔던 Eccentricity, Load Torque Oscillation을 좀더 심도있게 분석 , PM AM 을 WD 로 구별하는 방법씀 2006논문의 결과와 동일, Phase Modulation II. Air gap Eccentricity (AM) • Dynamic Eccentricity • Airgap permeance I. Load Torque Oscillations(PM)
8. 8 기계적 고장에 의한 Stator Current Modulation 에 관한 조사 3. [Distinguishing Load Torque Oscillations and Eccentricity Faults in Induction Motors Using Stator Current Wigner Distributions],2009,TIA, 144인용 • Airgap Magnetic Flux Density = MMF Sum X Permeance • Stator current MMF Sum Airgap Magnetic Flux Density Amplitude Modulation
9. 기계적 고장에 의한 Stator Current Modulation 에 관한 조사 9 III. Torque Oscillations Resulting From Eccentricity-> Eccentricity 있으면 결국 AM + PM 발생함을 설명 a nonzero torque is only produced if the pole-pair numbers of the interacting waves are equal + Time- varying torque is produced if the waves have equal pole-pair numbers and different pulsations. torque realistic eccentricity faults in practice include a mixture of static and dynamic eccentricity simultaneously, which is termed mixed eccentricity. In this case, additional p ± 1 pole-pair waves with pulsations ωs and ωs ± ωr are present. Oscillating torque 3. [Distinguishing Load Torque Oscillations and Eccentricity Faults in Induction Motors Using Stator Current Wigner Distributions],2009,TIA, 144인용
10. 10 기계적 고장에 의한 Stator Current Modulation 에 관한 조사 IV. WD 로 PM(Load Torque Oscillations )과 AM (Eccentricity, 사실 AM+PM)을 구별 • WD of PM • WD of AM lower sideband has the opposite sign to the upper sideband for a given point in time upper and lower sideband oscillations have the same amplitudes for a given point in time PM AM 합성된신호 실제신호 PM(Load Torque Oscillations ) AM+PM (Eccentricity) 3. [Distinguishing Load Torque Oscillations and Eccentricity Faults in Induction Motors Using Stator Current Wigner Distributions],2009,TIA, 144인용
11. 기계적 고장에 의한 Stator Current Modulation 에 관한 조사 4.[Hilbert versus Concordia transform for three-phase machine stator current time-frequency monitoring], Baptiste Trajin,2009,MSSP, 65인용 핵심 내용 : 앞선 Blodt et.al 논문에서는 eccentricity와 load torque oscillations와 같은 Mechanical faults 이 각각 AM and PM of stator current를 발생시킨다고 증명함. AM, PM 분석 위해 instantaneous amplitude (IA)와 instantaneous phase (IP)의 엄밀한 정의가 필요. 이를 위해 Complex signal이 필요. 전 통적으로 이를 위해 Hilbert Transform(HT)이 많이 쓰임. Bedrosian 조건에서는 분리된 modulation이 가 능했지만 일부 Mechanical faults는 이 조건을 위반함(Fast modulation일때). 그리하여 HT대신 Concordia transform (CT)를 이용하여 Complex vector 생성하여 Bedrosian 조건을 어기는 경우에 CT의 WD를 사용하여 Mechanical faults를 Fast/Slow modulation 모두에서 강건하게 진단하는게 목표. • Stator current (3상) Healthy Dynamic eccentricity pure Load torque oscillations Dynamic eccentricity+Load torque oscillations AM PM PM+AM
12. 4.[Hilbert versus Concordia transform for three-phase machine stator current time-frequency monitoring], Baptiste Trajin,2009,MSSP, 65인용 • Complex signal representation : univocal phase and amplitude definition을 위해 *Hilbert Transform(HT) : cancelation of negative frequency components Bedrosian condition *Concordia transform(CT) : cancelation of negative frequency components 기계적 고장에 의한 Stator Current Modulation 에 관한 조사
13. 4.[Hilbert versus Concordia transform for three-phase machine stator current time-frequency monitoring], Baptiste Trajin,2009,MSSP, 65인용 • HT와 CT 비교 These extra harmonics may lead to a misleading diagnosis since pure AM and pure PM both appear as mixed AM/PM 깔끔함 Slow/Fast 일때가 다름 HT는 Fast modulation일때 sideband 다름 기계적 고장에 의한 Stator Current Modulation 에 관한 조사
14. [Induction motor stator current analysis for planetary gearbox fault diagnosis under time-varying speed conditions],2020,MSSP 14 1. • Air gap flux • Motor stator current ->amplitude modulation and phase modulation in faulty cases • Load torque fault-induced torque oscillation • Rotor angle PM(t) Speed oscillation 적분
15. [Induction motor stator current analysis for planetary gearbox fault diagnosis under time-varying speed conditions],2020,MSSP 15 1. • when gear fault and rotor eccentricity exist, a series of time-varying frequency sidebands are expected around the power supply frequency &
16. 16 2. • 기존 : In most of these techniques, time and frequency domain features are manually extracted from a vibration sensor and used for fault detection and diagnosis. • 이 논문 핵심 : MCSA for downstream mechanisms (e.g. gearboxes) , Sensor Fusion(feature level이 아닌 data level) , Deep Learning • 한계 : load 가 0일 때만 실험, sample - rate 50000Hz , 속도의 종류는 많지만 변속이 아님 • 이 논문에서 참고할만한 점 : 전처리(outlier 제거 이후 2차 버터워스 LPF 사용하여 노이즈 제거 ), 슬라이딩윈도 [Multisensor data fusion for gearbox fault diagnosis using 2-D convolutional neural network and motor current signature analysis],2020,MSSP The acquired data from multiple current sensors are fused by a novel 2-D convolutional neural network
17. 17 2. [Multisensor data fusion for gearbox fault diagnosis using 2-D convolutional neural network and motor current signature analysis],2020,MSSP 논의 사항 : 1. the information loss is minimized and the correlation between different sensors is preserved by applying different convolution filters on raw data stacked in a 2D matrix 2. mechanical anomaly within the downstream mechanical components driven by the attached motor generate unexpected oscillatory motion of the gearbox shaft both rotationally and radially. Such a motion directly influence on the air gap eccentricity which affects the air gap flux density. The stator will draw current according to the variation in the electromagnetic field. Since the variations in motor current are related to motion in downstream components a fault in the load part of the drive is seen from the induction machine by a variation of the load torque and these torque oscillations make the stator current modulated as well 3. It needs to be observed that the amplitude and location of sidebands (associated with fault) is not consistent in spectrums of both phases of motor current (Phase U and Phase W).
18. 18 2. [Multisensor data fusion for gearbox fault diagnosis using 2-D convolutional neural network and motor current signature analysis],2020,MSSP • a fault in the load part of the drive is seen from the induction machine by a variation of the load torque and these torque oscillations make the stator current modulated as well Load torque rotor angle Stator current
19. 19 3. Interturn short [Inter-Turn Short Circuit Detection Based on Modulation Signal Bispectrum Analysis of Motor Current Signals],2013 Stator faults causes uneven distribution of the air-gap flux waveform around the stator cross section, which allows the stator currents to be modulated by rotor slot frequency (유도전동기)
20. 20 기계적 고장에 의한 Stator Current Modulation 에 관한 조사 Blodt (2006,2008,2009) 논문 3개 1.[Mechanical Load Fault Detection in Induction Motors by Stator Current Time-Frequency Analysis],2006,TIA, 270인용 • faults causing torque oscillations Load Torque Oscillation의 관점에서 Stator Current분석

### Notes de l'éditeur

1. 궁금한점 : Oscillation과 Modulation 의 차이 (토크는 oscillation , 전류는 modulation 이라고 부름) 공부해야할 기본 개념 : Magnetomotive Force, permeance wave, Magnetic field 와 앞 두개의 물리량과의 관계, Magnetic Flux ,wigner distribution
2. in case of the considered fault, the stator current signal is no longer strictly stationary, because the frequency of one signal component is varying sinusoidally in time.
3. %PSD However, the major disadvantage of the PSD is that there exist other phenomena such as different forms of eccentricity [7] or bearing faults [8] that may cause spectral components at the same frequencies. Other types of modulation such as amplitude modulation have a similar effect on the PSD. Moreover, most stator current spectra will already contain these frequencies in practice due to an inherent level of eccentricity. %WD the constant component Ist is present at the fundamental frequency. In a logarithmic plot, this constant component will hide the oscillations of the fundamental due to its greater amplitude, and the frequency fs will appear constant in time as can be seen in the experimental results. %Spectrogram In comparison to the WD, the spectrogram shows no interference terms outside the signal components time-frequency support in case of multicomponent signals or nonlinear frequency modulations. The length of the sliding window h∗(t) determines time and frequency resolution. good frequency resolution needs a long observation window and therefore leads to a bad localization in time and vice versa [10]. Moreover, the window length has to be chosen based on a prior knowledge of the signal.
4. 알아야할 개념: modulus and argument of the space vector / quadrature
5. 알아야할 개념: modulus and argument of the space vector / quadrature
6. Statistics and Machine Learning Toolbox™  매트랩 : Bayesian optimization for tuning machine learning algorithms by searching for optimal hyperparameters
7. [32]M. Blodt, M. Chabert, ... J.R.-I.T. on, U. 2006, Mechanical load fault detection in induction motors by stator current time-frequency analysis, IEEE Trans. Ind. Appl. (2005) 1881–1888. https://doi.org/10.1109/IEMDC.2005.195977 ELECTRICAL SIGNATURE ANALYSIS OF SYNCHRONOUS MOTORS UNDER SOME MECHANICAL ANOMALIES [33] https://oaktrust.library.tamu.edu/bitstream/handle/1969.1/156349/Li%2C%20Yong.pdf?sequence=1&isAllowed=y
8. [32]M. Blodt, M. Chabert, ... J.R.-I.T. on, U. 2006, Mechanical load fault detection in induction motors by stator current time-frequency analysis, IEEE Trans. Ind. Appl. (2005) 1881–1888. https://doi.org/10.1109/IEMDC.2005.195977 [33] https://oaktrust.library.tamu.edu/bitstream/handle/1969.1/156349/Li%2C%20Yong.pdf?sequence=1&isAllowed=y ELECTRICAL SIGNATURE ANALYSIS OF SYNCHRONOUS MOTORS UNDER SOME MECHANICAL ANOMALIES
9. [32]M. Blodt, M. Chabert, ... J.R.-I.T. on, U. 2006, Mechanical load fault detection in induction motors by stator current time-frequency analysis, IEEE Trans. Ind. Appl. (2005) 1881–1888. https://doi.org/10.1109/IEMDC.2005.195977 ELECTRICAL SIGNATURE ANALYSIS OF SYNCHRONOUS MOTORS UNDER SOME MECHANICAL ANOMALIES [33] https://oaktrust.library.tamu.edu/bitstream/handle/1969.1/156349/Li%2C%20Yong.pdf?sequence=1&isAllowed=y
10. 궁금한점 : Oscillation과 Modulation 의 차이 (토크는 oscillation , 전류는 modulation 이라고 부름) 공부해야할 기본 개념 : Magnetomotive Force, permeance wave, Magnetic field 와 앞 두개의 물리량과의 관계, Magnetic Flux ,wigner distribution
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