36 results about "Harmonic order" patented technology

The invention belongs to the field of gear machining detection, and particularly relates to a cylindrical gear ghost order detection method and detection equipment based on tooth surface waviness analysis. The method comprises the following steps: firstly, acquiring tooth surface deviation data of each tooth in a gear, carrying out resampling, inclination error correction and de-modification on the tooth surface deviation data, and then combining the tooth surface deviation data into full-tooth deviation curves in four directions; and then extracting waviness data and generating a full-tooth waviness curve. After RC is carried out on a full-tooth waviness curve, on one hand, the full-tooth waviness curve is converted into a frequency domain signal for selecting a frequency range, on the other hand, spectral analysis is carried out on a waviness signal through an iterative sine wave fitting algorithm within the specified frequency range, sine wave components are extracted, and a corresponding order spectrum is generated. And finally, when a sine wave component of which the amplitude is greater than or equal to 0.02 mu m and which is in a non-integral multiple harmonic order with the tooth number exists in the order spectrum of the target gear, detecting the gear ghost order. According to the invention, the problem of lack of a high-precision and high-efficiency waviness analysis and gear ghost order detection method in the prior art is solved.

The invention discloses a non-Gaussian noise pollution spiral shaft rod type part measurement signal processing method, which can realize reliable purification of measurement signals, stable separation of bending deviation and spiral raceway morphology items and fitting reconstruction when pollution such as heavy tails, multiple peaks, burrs and sheet abnormal points exists. The method comprises the following steps: acquiring and synchronously registering measurement data of rotation and axial movement, establishing a joint fitting model for decomposing readings into deformation items and spiral raceway morphology items, and expressing the morphology items by multi-order harmonics, and a three-stage process is adopted to complete baseline establishment and coarse elimination, phase locking and fine filtering in sequence, and the harmonic order of the optimal spiral raceway morphology item is determined in a self-adaptive manner and finally reconstructed. The invention provides an effective solution for the problems that the continuous rotary scanning measurement signal of the spiral shaft rod type part is unstable in recovery and is easy to distort in reconstruction under the non-Gaussian noise pollution.

The invention discloses a fault monitoring method for an intelligent electric energy meter, and the method comprises the steps: collecting a current signal sequence, extracting a phasor vector of a specific harmonic order, mapping the phasor vector to a Clifford algebraic space to construct a multi-vector, calculating a curvature sensitive norm sequence, carrying out the trend separation, obtaining a degradation trend component sequence, and carrying out the fault monitoring of the intelligent electric energy meter. Curvature features are calculated in combination with the degradation feature indexes after temperature compensation, finally, the curvature features are matched with a predefined fault feature library to output a diagnosis result, geometric algebraic space is introduced into electric energy meter fault monitoring, 3 / 5 / 7 harmonic collaborative phase deviation is captured through geometric correlation coding of harmonic phasors, and the fault diagnosis accuracy of the electric energy meter is improved. The problem that the aging early-stage characteristics of the electric energy meter are submerged by noise is solved, and the detection rate of progressive faults in the electric energy meter is improved; the technical problem that the average detection rate of the current fault monitoring method of the intelligent electric energy meter on early progressive faults such as capacitor aging and metering chip degradation is low is solved.

The invention discloses a magnetic field modulation electro-magnetic excitation motor current harmonic suppression method based on voltage compensation. The method comprises the steps of obtaining self-inductance off-line data of an excitation winding according to an actual measurement or simulation result; calculating an average value, a harmonic order and an amplitude characteristic quantity based on excitation winding self-inductance off-line data; calculating an actively injected compensation voltage value in combination with the characteristic quantity and position and current information fed back in real time; superposing the compensation voltage value with the output voltage of the original PI controller to obtain a new reference voltage; a bipolar modulation method is adopted, a modulation wave and a carrier wave which are obtained through reference voltage are compared, a driving signal of an H-bridge switching tube is obtained, and therefore an exciting winding is driven to generate current after harmonic suppression. The invention provides a general harmonic suppression method suitable for a magnetic field modulation brushless electro-magnetic motor, and the method is easy to realize, can effectively suppress the current harmonic of an excitation winding, and guarantees the operation efficiency and stability of the motor.

The invention provides a power line carrier communication chip function test method and system, and relates to the technical field of communication technology, and the method comprises the steps: constructing a power line channel simulation test platform, and simulating the voltage fluctuation and power rapid switching working condition in an actual power grid through dynamically adjusting the power output and load switching; in the power line channel simulation test platform, the dynamic sudden change process of the power grid impedance is simulated by controlling the change rate of the load current; the method comprises the following steps: generating an interference signal containing multiple times of characteristic harmonics based on a preset harmonic order proportional relation while simulating dynamic sudden change of impedance, establishing an amplitude proportional coefficient between a reference harmonic and a target harmonic, and coordinating and setting the amplitude of each harmonic according to the proportional relation of the corresponding order, so as to simulate the dynamic sudden change of the impedance. A plurality of characteristic harmonics with a predetermined proportional relationship are obtained, and an interference signal is coupled to a power line channel. The method can accurately simulate the severe channel condition of an actual power grid, and accurately evaluates the communication reliability of the chip.

The invention relates to the technical field of mutual inductor harmonic current detection, and provides a mutual inductor harmonic current detection method and system. The mutual inductor harmonic current detection method comprises the following steps: carrying out fast Fourier transform on a preprocessed mutual inductor current signal, and extracting a harmonic current signal; extracting harmonic current signal local features of a short time scale from the harmonic current signal, and then capturing long-term time dependence of the harmonic current signal local features of the short time scale to obtain harmonic current signal features; variational mode decomposition is carried out on the harmonic current signal characteristics to obtain the amplitude of each harmonic, the proportion of the amplitude of each harmonic to the current amplitude of the rated current of the transformer is calculated, and error correction is carried out on each harmonic in combination with the pre-constructed mathematical relationship among the harmonic number, the current amplitude proportion and a correction coefficient to obtain the harmonic current. The total harmonic distortion rate is calculated according to the harmonic after error correction, harmonic current detection can be rapidly and accurately achieved, and the influence of noise interference on detection precision is reduced.

The invention relates to the technical field of power system protection, and discloses a direct-current line bipolar short-circuit fault protection method based on harmonic impedance, which comprises the following steps: measuring a voltage waveform signal and a current waveform signal of a direct-current line protection position in real time; processing the voltage waveform signal and the current waveform signal by adopting short-time Fourier transform, and extracting a high-frequency voltage component and a high-frequency current component of a specific harmonic order; calculating a module value and a phase angle of the high-frequency voltage component and a module value and a phase angle of the high-frequency current component, and obtaining harmonic impedance through voltage division calculation; the fault position is determined according to the harmonic impedance change of each line before and after the fault occurs; the fault position is determined through the harmonic impedance change of each line before and after the fault occurs, and a rapid, reliable and economical protection scheme is provided for the bipolar short-circuit fault of the direct-current line.

The application discloses a kind of electric quantity use situation prompt and safety early warning monitoring method and system, comprising: acquisition low-frequency metering and high-frequency harmonic channel data, generate analysis window signal;Parameterized spectrum estimation obtains harmonic order, frequency, amplitude, phase and filters effective component;Rotary harmonic state sequence is constructed, and total harmonic distortion and sub-band energy are calculated;With low-frequency data and harmonic index as exogenous input, structured state space model is constructed, and multiple-step prediction and hidden state are output;Gated fusion state sequence and hidden state, limit parameter search range;Construct joint optimization target, end-to-end training and solidify model structure and parameter;Model deployment generates electric quantity and harmonic trend prediction, trigger prompt and early warning and output to visual terminal.The application realizes the accurate prediction of electric quantity use trend and harmonic index and over-limit safety early warning by fusing multi-channel sampling, harmonic state modeling and structured state space prediction.

The invention discloses an electric quantity use condition prompting and safety early warning monitoring method and system, and the method comprises the steps: collecting low-frequency metering and high-frequency harmonic channel data, and generating an analysis window signal; performing parametric spectrum estimation to obtain harmonic order, frequency, amplitude and phase, and screening effective components; constructing a rotary type harmonic state sequence, and calculating total harmonic distortion and zoning energy; low-frequency data and harmonic indexes are used as exogenous input, a structured state space model is constructed, and multi-step prediction and hidden states are output; gating a fusion state sequence and a hidden state, and limiting a parameter search range; constructing a joint optimization target, performing end-to-end training, and solidifying a model structure and parameters; and the deployment model generates electric quantity and harmonic trend prediction, triggers prompt and early warning, and outputs the information to a visual terminal. According to the invention, through fusion of multi-channel sampling, harmonic state modeling and structured state space prediction, accurate prediction and over-limit safety early warning of an electric quantity use trend and a harmonic index are realized.

This application discloses a method for extracting the DC component of an AC signal, comprising: acquiring the AC signal to be processed and its fundamental angular frequency; sequentially performing low-frequency harmonic elimination processing on the AC signal according to the fundamental angular frequency in descending order of harmonic order, wherein each low-frequency harmonic elimination process is configured to: eliminate the current target low-frequency harmonic, while amplifying the high-frequency noise and higher-order harmonics in the AC signal that have not been eliminated, causing the high-frequency noise and higher-order harmonics to trigger amplitude limiting; after completing a preset number of low-frequency harmonic elimination processes, filtering the obtained signal to extract the target DC component from the AC signal; wherein the amplitude limiting value is set to be significantly higher than the amplitude of the target DC component in the AC signal, so that the amplitude of the high-frequency noise and higher-order harmonics after amplitude limiting is far away from the amplitude of the target DC component. This method can achieve fast and accurate extraction of the target DC component.

A drive motor and a retarder in a powertrain meet a condition that a harmonic order of the drive motor is the same as a quantity of gear teeth of an input shaft gear in the retarder such that a frequency of an electromagnetic noise harmonic generated by the drive motor is the same as a frequency of a noise harmonic generated by the retarder. When the drive motor and the retarder are coupled using a connection structure, a phase of the electromagnetic noise harmonic generated by the drive motor differs from a phase of the noise harmonic generated by the retarder by a set angle.

The invention discloses a 690V low-voltage equipment load harmonic suppression system suitable for an LNG station, and relates to the technical field of electric energy quality governance, and the system comprises a comprehensive management center which is in communication connection with the following modules: a power grid state sensing modeling module which is used for monitoring power grid impedance, background harmonic waves and load working conditions, a dynamic grid model is constructed to output a grid state covering impedance, harmonic order, and load power. According to the invention, multiple sensors and monitoring devices are integrated, multi-source data of 690V bus harmonic frequency spectrum, impedance parameters and equipment operation states are collected in real time, errors are eliminated by utilizing multi-source data fusion, a dynamic power grid model is constructed, power grid impedance, background harmonic waves and load working conditions are accurately monitored, potential problems can be found in advance, and the power grid reliability is improved. And a basis is provided for harmonic suppression, and stable operation of the 690V low-voltage equipment of the LNG field station in a complex power grid environment is guaranteed.

The invention discloses a bilateral permanent magnet fault-tolerant permanent magnet vernier motor and a torque increasing and eddy current loss reducing coupling analysis method thereof. Based on harmonic magnetic field analysis, contribution of each harmonic to torque and distribution characteristics of permanent magnet eddy current loss are decomposed, and classification control is carried out on the harmonic through comprehensive parameter optimization. The method specifically comprises the steps that a rotor adopts a consequent pole design, and a bidirectional magnetism gathering effect is formed by combining a stator split tooth embedded reverse Halbach array permanent magnet; based on magnetic field harmonic decomposition, contribution rates of different harmonic orders (such as 3, 7, 23 and the like) to output torque are quantified, and key gain harmonics and loss harmonics are identified; a permanent magnet eddy current loss model is established, and the proportion of specific harmonic orders (such as 10 times, 20 times and the like) to permanent magnet eddy current loss is deduced in combination with harmonic frequency and amplitude. A harmonic torque-loss tradeoff coefficient is defined, the harmonic amplitude, frequency and loss density are combined, risk grading is carried out on each harmonic of the motor, and the design priority is guided.

The invention relates to the technical field of power systems, in particular to a harmonic source dynamic monitoring and responsibility distribution platform and method, and the platform comprises the following steps: a real-time monitoring module, a harmonic source positioning module, a responsibility distribution module, an alarm and event recording module and a data management and analysis module. According to the system, the time domain sampling density of high-frequency harmonics is remarkably improved, the sampling rate of 20 kHz enables the number of sampling points in a single period to be increased to 6.67 points from 1.67 points in the sampling process of 5 kHz, the problem of waveform distortion caused by time domain signal discretization is effectively solved, the actually measured harmonic amplitude error is converged to be within + / -5% from + / -30%, the phase error is reduced to be negligible, and the method has the advantages that the method is simple and easy to implement. The method can automatically detect and correct error frequency components in a frequency spectrum, and when 18kHz harmonic waves are aliasing to 2kHz due to undersampling, the algorithm matches with a harmonic wave prior model through amplitude correlation analysis, and redistributes energy to real frequency points, so that the identification accuracy of harmonic wave times is improved, and a real and reliable data basis is provided for subsequent analysis.

The application discloses a permanent magnet synchronous motor NVH optimization method based on frequency adaptive repetitive control, and comprises the following steps: S1, an air gap magnetic field model generated by a permanent magnet and an armature reaction is established; S2, a relationship between a radial electromagnetic force order and a three-phase current harmonic order is derived according to the air gap magnetic field model; S3, a frequency adaptive repetitive control algorithm is used to suppress the harmonic of the dq-axis current; and S4, a joint simulation platform is built to verify the effect. The frequency adaptive repetitive controller and the PI controller are used to suppress the harmonic in the current loop, the harmonic content of the three-phase current of the motor is greatly reduced, and the NVH performance of the motor is improved.

The invention provides an equipment fault assessment method and device, electronic equipment and a storage medium, and the method comprises the steps: obtaining the monitoring data of a stress wave monitoring system for equipment, and obtaining a frequency sequence and an amplitude sequence of a target time period based on the monitoring data of the stress wave monitoring system, selecting a preset number of elements with maximum local amplitudes from the amplitude sequence as a target amplitude set, obtaining a target subscript set based on the target amplitude set, obtaining a center frequency set according to the target subscript set and the frequency sequence, performing harmonic relation analysis on the center frequency set to obtain a harmonic order set, and obtaining a harmonic order set; and performing sideband analysis on the center frequency set based on a preset window range to obtain a sideband information set, generating an evaluation result set according to the sideband information set and the harmonic frequency set, and comparing the evaluation result set with a preset fault frequency to obtain a fault evaluation result of the equipment. The technical problems of high fault analysis difficulty and low accuracy of equipment frequency spectrum data acquired by a stress wave monitoring system are solved.

The present application belongs to the field of harmonic analysis, and provides a harmonic disturbance analysis method and system based on harmonic active power distribution, which carries out pretreatment on the obtained three-phase voltage and current data of each node, separates the fundamental wave and harmonic components through orthogonal transformation, calculates the instantaneous harmonic active power of each node under the reference working condition, calculates and counts the average harmonic active power under the steady state, calculates the harmonic active power of each node under the working condition of single or multiple harmonic sources, carries out difference processing on the harmonic active power under the working condition and the harmonic active power under the reference working condition, obtains the node harmonic active power increment distribution of the to-be-tested working condition relative to the reference working condition, and preliminarily determines the harmonic source position; according to the positive and negative directions, amplitude size and change law along the topology path of the harmonic active power of each node, a harmonic active power distribution propagation heat map is drawn, and the dominant harmonic order, the frequency prone to harmonic amplification and the harmonic disturbance sensitive area are identified. The present application realizes accurate analysis of harmonics.

Embodiments of the present application disclose a pre-processing matrix multiplexing method and device, electronic equipment and a storage medium; the method comprises: obtaining simulation parameters of a to-be-simulated circuit, and generating frequencies corresponding to each harmonic according to a fundamental frequency and a maximum harmonic order in the simulation parameters; dividing the frequencies corresponding to each harmonic into a plurality of frequency groups according to the size of the frequencies corresponding to each harmonic; determining representative frequencies of each frequency group, and constructing a pre-processing matrix corresponding to each frequency group based on the representative frequencies.

This invention discloses a broadband oscillation assessment method, apparatus, and device. By applying harmonic voltage and current sources, it calculates the node harmonic response values ​​at different harmonic orders, plots node harmonic response curves based on these values, and determines whether a node has a resonance risk based on the curves. This method does not rely on the accuracy of system modeling and does not require system disconnection or shutdown. Compared to pre-assessment methods, it is more accurate and more flexible than on-site protection assessment methods, solving the technical problems of poor accuracy and flexibility in existing broadband oscillation assessment methods.

The invention discloses a motor vibration noise suppression method and device, and the method comprises the steps: inputting a direct-axis target current and a quadrature-axis target current into a PI controller, and obtaining a direct-axis DC voltage and a quadrature-axis DC voltage; an R controller is added into a PI controller, and in the parameter adjusting process of the PIR controller, the vibration acceleration and harmonic component of each current harmonic order are recorded, and direct-axis alternating voltage and quadrature-axis alternating voltage are extracted; determining a direct-axis compensation voltage and a quadrature-axis compensation voltage; based on the sum value of the direct-axis direct-current voltage and the direct-axis compensation voltage; calculating the sum value of the quadrature-axis DC voltage and the quadrature-axis compensation voltage; and suppressing the vibration noise of the motor according to the final direct-axis voltage and the final quadrature-axis voltage. The harmonic voltage amplitude is extracted through closed-loop control, then the harmonic voltage phase (namely a sinusoidal signal) is calibrated through open-loop control, and by means of the method combining closed-loop and open-loop harmonic injection, the stability of the system is high, and instability caused by improper parameters is not likely to happen.

The invention relates to a vibration measurement method of a scanning type laser Doppler vibration meter capable of avoiding harmonic interference, which comprises the following steps of: S1, arranging a reference point on a scanning path of the vibration meter, scanning the vibration of the reference point so as to acquire a rough measurement vibration signal of a measured object, and carrying out segmented filtering processing; s2, determining the fundamental frequency f and the maximum harmonic order nmax of the measured object according to the filtered roughly measured vibration signal, and calculating the fundamental frequency f and the distribution range of each order of harmonic frequency; s3, acquiring a scanning frequency fs, judging whether fs is overlapped with the harmonic frequency of each order or not, if yes, adding an offset delta f on the basis of the scanning frequency fs, and returning to the step S3; if not, the scanning frequency fs serves as the actual scanning frequency fs', and then the step S4 is executed, and S4, the actual scanning frequency fs' is adopted to scan the measured object to obtain vibration signal data, the scanning frequency and all harmonic frequencies are not overlapped, and then harmonic interference is avoided.

The invention discloses a wind power plant harmonic source positioning method and device, terminal equipment and a storage medium, and belongs to the technical field of wind power generation. The method comprises the following steps: acquiring an electrical network topology of a wind power plant, a plurality of preset harmonic frequencies, real-time operation data of a wind power generation unit under each preset harmonic frequency and electrical element parameters of the wind power plant under each preset harmonic frequency; for each preset harmonic order, constructing a frequency-dependent electrical diagram under the current preset harmonic order according to the acquired data; determining a harmonic source sparse estimation result of the wind power plant under the current preset harmonic order according to the frequency-dependent electrical diagram under each preset harmonic order; and positioning the harmonic source of the wind power plant according to the harmonic source sparse estimation result of the wind power plant under each preset harmonic order. The method can solve the problem of difficulty in positioning the harmonic source in the wind power plant in the prior art, and can improve the positioning accuracy of the harmonic source in the wind power plant.

The invention relates to a fractional slot concentrated winding permanent magnet motor demagnetization space distribution self-adaptive compensation method, which comprises the steps of collecting a motor driving physical quantity, calculating a permanent magnet flux linkage estimation value based on the motor driving physical quantity, generating a flux linkage residual error sequence, performing frequency domain analysis on the flux linkage residual error sequence, and obtaining a target fault harmonic order. An analytical model of the demagnetization area is constructed, and an equivalent flux linkage loss function is obtained; performing Fourier series expansion on the equivalent flux linkage loss function to obtain a harmonic complex coefficient set for constructing an error function for demagnetization space distribution parameters, and performing iterative solution on the demagnetization space distribution parameters by using a parameter inversion model by taking the error function as a target to obtain an identification result; and constructing an equivalent permanent magnet flux linkage function under the current rotor electrical angle by using an identification result to correct a d-axis current instruction, setting a compensation voltage vector orthogonal to a demagnetization flux linkage harmonic wave, and superposing the compensation voltage vector to a PI output end in a feedforward form to generate a final d-q voltage instruction.

The present invention discloses a harmonic family detection method based on multi-window joint detection and harmonic feature evaluation, which includes the following steps: first, obtaining a data sequence; second, initializing parameters; third, obtaining a normalized amplitude spectrum; fourth, obtaining a joint detection window center vector, a line spectrum frequency vector, and a line spectrum energy vector; fifth, updating the line spectrum frequency vector and the line spectrum energy vector; sixth, obtaining an effective harmonic order vector; seventh, calculating a greatest common divisor; eighth, updating the extracted fundamental frequency; ninth, judging whether a fundamental frequency search end condition is met, if so, proceeding to step ten, otherwise, returning to step four; tenth, judging whether a time frame traversal end condition is met, if so, proceeding to step eleven, otherwise, returning to step three; and eleventh, outputting the fundamental frequency extracted from each time frame. The method can effectively detect harmonic families under the condition that there are single or multiple harmonic families.

The invention relates to the technical field of online monitoring of transformers, in particular to an online monitoring operation method of a three-phase low-voltage current transformer. Comprising the following steps: acquiring secondary current of a three-phase low-voltage current transformer, and calculating secondary zero-sequence current of the secondary side of the three-phase low-voltage current transformer; the primary zero-sequence current of the primary side of the three-phase low-voltage current transformer is obtained through the zero-sequence current transformer, and the standard secondary zero-sequence current of the secondary side of the three-phase low-voltage current transformer is calculated. The harmonic synthesis error of the three-phase low-voltage current transformer under each harmonic is finally calculated through the ratio of the secondary zero-sequence current to the standard secondary zero-sequence current, a fault decision factor is calculated according to the weight coefficient of each harmonic synthesis error, and when the fault decision factor is greater than a corresponding fault threshold, the three-phase low-voltage current transformer is judged to be in a fault state. And determining that the three-phase low-voltage current transformer has a fault. On-line monitoring of the three-phase low-voltage current transformer can be realized through the fault judgment factor, and the accuracy of fault judgment is improved.

This application discloses a method and system for adjusting the capacity of a distribution transformer based on adaptive linear neurons, relating to the field of electrical equipment and power system automation. The method includes: inputting the secondary current to an adaptive linear neuron filter to filter out harmonic components corresponding to harmonic orders in the secondary current, and outputting the fundamental frequency component; the adaptive linear neuron filter constructs a corresponding input vector based on the harmonic order and the fundamental frequency component, the input vector including the sine and cosine components of the harmonic order, and the sine and cosine components of the fundamental frequency component; calculating the amplitude of the fundamental frequency component, comparing the amplitude of the fundamental frequency component with a preset capacity adjustment threshold, generating a switching control signal for the IGBT, and controlling the switching state of the distribution transformer windings according to the switching control signal. This application solves the technical problem that current methods using secondary current as the capacity adjustment criterion result in inaccurate estimation of the transformer's fundamental frequency capacity, leading to the transformer entering a high-capacity state prematurely or a low-capacity state too late.

A method for controlling operation of a rotating electric machine includes receiving, via a bandwidth partitioned harmonic compensation regulator (HCR) of a controller, an instruction torque and a rotational speed of the machine, and using the instruction torque and the rotational speed to calculate dq harmonic compensation currents and voltages for one or more predetermined harmonic orders via the HCR in response to an enable condition. The harmonic compensation currents and voltages cancel torque and current fluctuations in the one or more predetermined harmonic orders. The method can include injecting acoustic tones at the predetermined harmonic orders. The method also includes adding the dq harmonic compensation currents and voltages to dq current and voltage instructions, respectively, to produce adjusted dq current and voltage instructions. The adjusted dq current and voltage instructions are then used to control the machine.

In a method for reducing harmonics in a drive system (10) of an electrically powered vehicle, at least one sensor signal containing harmonics of the rotor frequency (f) is used. R ) in a harmonic order (n) to be reduced, is detected. An amplitude (A) and a phase (φ) of the harmonic of a single order (n) to be reduced are derived from the sensor signal (S). M ) is extracted. A reduction signal (S) is generated. R ) with the frequency of the harmonic of the order (n) to be reduced based on the extracted amplitude (A) and phase (φ) and the reduction signal (S R ) becomes a motor voltage signal (U M The values ​​are added such that the amplitude (A) of the harmonic of the order (n) to be reduced is reduced. A control unit (24) of the drive system (10) is designed to execute the procedure.

This invention discloses a multi-frequency sinusoidal coherent undersampling method and apparatus. The method includes targeting different harmonic orders. h ,judge pq h < N Is / 2 true? If true, then the first... h The recovered spectrum of the subharmonic R h Values pq h Otherwise, in pq h % N < N When / 2 is established, the first h The recovered spectrum of the subharmonic R h Values pq h % N ,exist pq h % N < N If / 2 is not true, then the first h The recovered spectrum of the subharmonic R h Values N - pq h % N By utilizing the number of sampling points N The accumulation is used to filter out those that will not cause spectral line overlap. N By taking values ​​and obtaining the corresponding spectral line mapping relationships, the spectral line positions of the multi-frequency sinusoidal signal under normal sampling conditions can be recovered. This invention aims to quickly determine all possible undersampled frequencies and the positions of aliasing frequencies in the spectrum of an arbitrary given spectral distribution multi-frequency sinusoidal signal, thereby achieving lossless recovery of the original spectrum of the multi-frequency sinusoidal signal.

This invention relates to an adaptive time-frequency joint filtering method for electrostatic data from solid rocket motor exhaust. The method includes the following steps: constructing a main channel filtering algorithm to suppress the fundamental combustion oscillation, employing an adaptive IIR notch filter, with the core frequency detected by a real-time FFT algorithm and the bandwidth dynamically adjusted according to the combustion state; constructing an auxiliary channel to suppress harmonics, consisting of multiple parallel notch filters, each corresponding to a harmonic frequency, with the harmonic order adaptively determined based on the fundamental attenuation; addressing the phase distortion problem of traditional IIR filters by using forward-backward filtering to offset phase shift; particle pulse detection is the core of solid rocket motor exhaust electrostatic signal processing, aiming to accurately identify transient pulses (1-5 μs) generated by Al2O3 particle collisions; this invention uses a wavelet domain adaptive algorithm based on multi-scale noise separation, a time-varying threshold mechanism, and the SURE optimization criterion to suppress combustion oscillations and noise in the exhaust electrostatic signal while preserving particle pulse information.