CN-120429767-B - Bearing fault acoustic detection method and system based on fractional harmonic phase-locked amplification

CN120429767BCN 120429767 BCN120429767 BCN 120429767BCN-120429767-B

Abstract

The invention discloses a bearing fault acoustic detection method and system based on fractional harmonic phase-locked amplification, which are used for acquiring an acoustic signal of a target motor, measuring the shaft rotation frequency of a motor shaft in real time, synchronizing the shaft rotation frequency to a fractional phase-locked loop, calculating the bearing fault characteristic frequency according to the geometric parameter of a bearing, generating a reference signal synchronous with the bearing fault characteristic frequency through the fractional phase-locked loop, carrying out phase sensitive detection on the acquired acoustic signal and the generated reference signal by using a phase-locked amplifier, specifically, carrying out quadrature demodulation on the acoustic signal and the reference signal, generating an in-phase component and a quadrature component, extracting a direct current component through low-pass filtering, further calculating vibration amplitude and phase information corresponding to the bearing fault characteristic frequency, and judging the type and severity of the bearing fault according to the comparison, harmonic consistency and phase stability of the vibration amplitude and a preset base line.

Inventors

LIU DONGSHENG
LI JIAWEI
CHEN YAHUI
GUO FEIPENG

Assignees

浙江工商大学

Dates

Publication Date: 20260512
Application Date: 20250410

Claims (8)

1. The bearing fault acoustic detection method based on fractional harmonic phase lock amplification is characterized by comprising the following steps of: acquiring acoustic signals of a shaft and a bearing which are cooperatively arranged; acquiring the shaft rotation frequency of the shaft and synchronizing to a fractional phase-locked loop; Calculating a bearing fault characteristic frequency according to the geometric parameters of the bearing, wherein the bearing fault characteristic frequency is a non-integer multiple of the rotation frequency of the shaft; The fractional phase-locked loop acquires the shaft rotation frequency, the phase frequency detector is used for carrying out phase comparison on the shaft rotation frequency and a feedback signal which is output by the voltage-controlled oscillator and is subjected to frequency division by the frequency divider, an error signal which is proportional to the phase difference is output, so that the charge pump is driven to generate a voltage signal, the voltage signal is filtered by the low-pass filter to remove high-frequency noise, direct-current control voltage is generated, the voltage-controlled oscillator is used for generating a high-frequency signal according to the direct-current control voltage, the output frequency of the voltage-controlled oscillator is in linear relation with the control voltage, the frequency-divided signal is subjected to dynamic frequency division by the fractional frequency divider, the frequency-divided signal is fed back to the voltage-controlled oscillator to form closed loop control, and finally the fractional phase-locked loop outputs a reference signal which is locked with the shaft rotation frequency in phase; The phase-locked amplifier is used for carrying out phase sensitive detection on the acoustic signal and the reference signal, carrying out quadrature demodulation on the acoustic signal and the reference signal to generate an in-phase component and a quadrature component, extracting a direct current component through low-pass filtering, and carrying out quadrature demodulation to obtain vibration amplitude and phase information corresponding to the bearing fault characteristic frequency; and judging the type and severity of the bearing fault according to the comparison of the vibration amplitude and a preset baseline, the consistency of harmonic waves and the phase stability.
2. The method for detecting bearing fault acoustics based on fractional harmonic phase-locked amplification according to claim 1, wherein the dynamic frequency division is characterized in that the frequency division ratio is a non-integer, and the frequency divider achieves fractional frequency division through the average effect of alternately switching integer frequency division values.
3. The method for acoustically detecting a bearing failure based on fractional harmonic phase lock amplification of claim 1, wherein the characteristic frequency of the bearing failure is based on an obtained rotational frequency of the shaft and based on a number of balls of the bearing Diameter of ball Diameter of pitch circle Contact angle Obtained by the following formula: Wherein, the The characteristic frequency of the failure of the inner ring of the bearing is shown, Represents the failure characteristic frequency of the outer ring of the bearing, m BPFI represents the non-integer multiple coefficient of the failure characteristic frequency of the inner ring of the bearing, m BPFO represents the non-integer multiple coefficient of the failure characteristic frequency of the outer ring of the bearing, Indicating the frequency of rotation of the shaft, Which represents the angular frequency of the light emitted by the light source, The contact angle, i.e. the angle between the bearing and the outer race raceway, is indicated.
4. The method for detecting bearing failure acoustic detection based on fractional harmonic phase-locked amplification according to claim 1, wherein the phase-locked amplifier multiplies the acoustic signal by the reference signal and its quadrature signal respectively to generate an in-phase component and a quadrature component, extracts a DC component by low-pass filtering, and obtains a homodromous component of the DC component And quadrature component of DC component ; Calculating a composite amplitude by the homodromous component of the DC component and the quadrature component of the DC component And phase difference : According to the combined amplitude Preset reference amplitude And reference phase The vibration amplitude and phase difference are calculated as follows: Wherein, the Representing the amplitude of the vibration, Indicating the phase difference.
5. The method for detecting bearing faults based on fractional harmonic phase-locked amplification as claimed in claim 1, wherein a frequency synthesizer is integrated by using the fractional phase-locked loop to generate a multi-order harmonic reference signal as an extension of the reference signal, and the frequency of different fault characteristics possibly existing in the bearing is detected by using the following calculation formula: Wherein, the Representing the reference signal of the multi-order harmonic, Representing the order of the harmonic wave for a preset positive integer, A non-integer multiple of the characteristic frequency of bearing failure, Representing the shaft rotation frequency; and carrying out quadrature demodulation on the acoustic signal and the multi-order harmonic reference signal to generate a multi-order in-phase component and a multi-order quadrature component, extracting a multi-order direct current component through low-pass filtering, and further calculating to obtain multi-order harmonic vibration amplitude and multi-order phase information corresponding to the bearing fault characteristic frequency.
6. The method for acoustically detecting the bearing fault based on the fractional harmonic phase lock amplification according to claim 5, wherein the judgment of the bearing fault is as follows: measuring and recording vibration amplitude baseline threshold values of fault characteristic frequencies of all bearings in a fault-free state, and acquiring vibration amplitude values of target bearings in real time Phase difference A multi-order harmonic vibration amplitude; when measuring vibration amplitude in real time Triggering fault early warning when the baseline threshold value is exceeded; Verifying whether the amplitude of the multi-order harmonic vibration corresponding to the bearing fault characteristic frequency is synchronously increased; calculating the phase difference Standard deviation of (2) If (if) <0.1Rad, then the confirmation signal originates from the target bearing; determining fault positions according to the characteristic frequency of the abnormal vibration amplitude, and dividing the severity according to the multiple of the vibration amplitude exceeding a base line, wherein the multiple is positively correlated with the severity.
7. Bearing fault acoustic detection system based on fractional harmonic phase-locked amplification, including fractional phase-locked loop, lock-in amplifier and fault diagnosis module, its characterized in that: the fractional phase-locked loop generates a reference signal synchronous with the bearing fault characteristic frequency according to the acquired shaft rotation frequency; the fractional phase-locked loop comprises a phase frequency detector, a charge pump, a low-pass filter and a fractional frequency divider, wherein the phase frequency detector is used for comparing the acquired shaft rotation frequency with a feedback signal obtained by frequency division of the frequency divider output by the voltage-controlled oscillator to output an error signal proportional to a phase difference so as to drive the charge pump to generate a voltage signal, the low-pass filter is used for filtering the voltage signal to remove high-frequency noise so as to generate a direct-current control voltage, the voltage-controlled oscillator is used for generating a high-frequency signal according to the direct-current control voltage, the output frequency of the high-frequency signal is in a linear relation with the control voltage, and the fractional frequency divider is used for dynamically dividing the high-frequency signal and feeding back the divided signal to the voltage-controlled oscillator so as to form closed loop control, so that the fractional phase-locked loop finally outputs a reference signal locked with the shaft rotation frequency; The phase-locked amplifier is used for carrying out phase sensitive detection on acoustic signals of the shaft and the bearing and the corresponding reference signals, carrying out quadrature demodulation on the acoustic signals and the reference signals to generate in-phase components and quadrature components, extracting direct-current components through low-pass filtering, and obtaining vibration amplitude and phase information corresponding to the fault characteristic frequency of the bearing after demodulation of the phase-locked amplifier; The fault diagnosis module judges the type and severity of the bearing fault according to the comparison of the vibration amplitude and a preset baseline, the consistency of harmonic waves and the phase stability.
8. The bearing fault acoustic detection system based on fractional harmonic phase-locked amplification as claimed in claim 7, wherein said phase-locked amplifier comprises a multiplier, a low-pass filter and a quadrature demodulation module; The multiplier multiplies the acoustic signal with the reference signal and the quadrature signal thereof respectively to generate an in-phase component and a quadrature component; the low-pass filter extracts the direct current component to obtain the homodromous component And orthogonal component ; The quadrature demodulation module calculates a synthesized amplitude value through the homodromous component and the quadrature component And phase difference : According to the combined amplitude Preset reference amplitude And reference phase The vibration amplitude and phase difference are calculated as follows: Wherein, the Representing the amplitude of the vibration, Indicating the phase difference.

Description

Bearing fault acoustic detection method and system based on fractional harmonic phase-locked amplification Technical Field The invention belongs to the technical field of mechanical fault diagnosis and signal processing, and particularly relates to a bearing fault acoustic detection method and system based on fractional harmonic phase-locked amplification. Background In the industrial field, an electric motor is a key power device, and the stability and reliability of operation of the electric motor are important. And the bearing is used as one of the core components of the motor and plays an important role in supporting and guiding the rotation of the rotor. Related studies have shown that 30% -40% of motor failures are due to rolling bearing failures. Bearing failure is typically manifested as surface damage to the primary elements (e.g., outer race, inner race, cage, or rolling elements). The faults not only can cause abnormal vibration and noise when the motor operates, but also can obviously reduce the efficiency and service life of the motor, and even cause the motor to stop when serious, so that huge economic loss is brought to industrial production. Currently, the technology for bearing failure detection is of a wide variety. Vibration signal Analysis (AVS) is a relatively mature method, and faults are judged by monitoring the characteristics of amplitude, frequency and the like of bearing vibration, but in practical application, the installation position and direction of a vibration sensor have a relatively large influence on a detection result and are easily interfered by external vibration. Motor Current Signature Analysis (MCSA) indirectly detects bearing faults by analyzing changes in motor current. However, factors such as load variation and power supply fluctuation of the motor can interfere with the current signal, so that accuracy of the detection result is affected. In addition, there are thermal imaging techniques, optical fiber sensing techniques, magnetic field detection techniques, acoustic emission detection techniques, and the like. Although the acoustic emission detection technology has higher sensitivity to early faults, a sensor needs to be installed in equipment, and the acoustic emission detection technology belongs to invasive detection and has higher requirements on detection environments. In contrast, detection methods based on acoustic signals have unique advantages. The sound signal contains rich equipment running state information, and through air propagation, no direct contact with equipment is needed, and non-invasive detection can be realized. However, in a practical industrial environment, sound signal detection presents a significant challenge. Because of a large amount of background noise and vibration interference of other equipment in an industrial field, a target sound signal is often severely polluted, so that the signal-to-noise ratio (SNR) of the signal is extremely low, and the traditional frequency analysis method based on Fourier transform and the like is difficult to accurately extract the fault characteristic frequency. For example, in a factory workshop, various mechanical devices are operated simultaneously, and the generated noises are superimposed on each other, so that weak sound signals generated by bearing faults are submerged therein, which is difficult to be effectively detected and analyzed. Disclosure of Invention In order to solve the defects in the prior art, the aim of overcoming the signal-to-noise ratio limitation in sound signal detection and improving the bearing fault detection precision is fulfilled, and the invention adopts the following technical scheme: the bearing fault acoustic detection method based on fractional harmonic phase lock amplification comprises the following steps: acquiring acoustic signals of a shaft and a bearing which are cooperatively arranged; acquiring the shaft rotation frequency of the shaft and synchronizing to a fractional phase-locked loop; Calculating a bearing fault characteristic frequency according to the geometric parameters of the bearing, wherein the bearing fault characteristic frequency is a non-integer multiple of the rotation frequency of the shaft; Generating a reference signal synchronous with the bearing fault characteristic frequency through the fractional phase-locked loop; The phase-locked amplifier is used for carrying out phase sensitive detection on the acoustic signal and the reference signal, carrying out quadrature demodulation on the acoustic signal and the reference signal to generate an in-phase component and a quadrature component, extracting a direct current component through low-pass filtering, and carrying out quadrature demodulation to obtain vibration amplitude and phase information corresponding to the bearing fault characteristic frequency; and judging the type and severity of the bearing fault according to the comparison of the vibration amplitude and a preset baseline, th