18 results about "Harmonic interference" patented technology

The utility model belongs to the technical field of electronic circuit, especially relates to a passive low harmonic frequency converter special for rail transit air conditioner. The frequency converter includes: passive filter module, rectifier module, precharge module, voltage-sharing filter module, inverter module and control module. The input end of passive filter module is connected to the output end of alternating -current source, and the output end is connected to the input end of rectifier module, and the output end of rectifier module is connected to the input end of precharge module, the output end of precharge module is connected to the input end of voltage-sharing filter module, the output end of voltage-sharing filter module is connected to the input end of inverter module, and the output end of inverter module is the voltage output end of passive low harmonic frequency converter special for rail transit air conditioner, and inverter module and control module are connected through inverter control and protection circuit. The utility model can reduce the harmonic interference of frequency converter inverter to input power grid, protects the electrical equipment on power grid, and improves the security of operation.

The embodiment of the application discloses a fault analysis method and related device, and processing equipment can determine the energy band quantity corresponding to the vibration signal to be analyzed first, and the energy band quantity can reflect whether the transformer is disturbed by harmonic interference. In response to the energy band quantity being greater than a preset threshold, the processing equipment can determine that the transformer has received harmonic interference, thereby determining a harmonic interference vibration signal. Then, the processing equipment can determine a harmonic characteristic frequency used to reflect the vibration characteristics of the transformer to be analyzed under harmonic interference, determine whether the transformer to be analyzed has a fault according to the similarity between the harmonic characteristic frequencies corresponding to the plurality of harmonic interference vibration signals, and if the similarity is high, it indicates that the transformer has relatively stable vibration characteristics in a plurality of time periods, and there is a high probability that the transformer has no fault, thereby realizing fault analysis on the transformer disturbed by harmonic interference and accurate judgment on the transformer fault.

The application provides a method and device for evaluating the harmonic interference degree of a converter transformer by using a vibration signal. The method comprises the following steps: collecting multiple vibration signals collected by multiple vibration sensors as vibration samples; obtaining the frequency spectrum of each vibration sample; constructing a discrete frequency spectrum sequence of the vibration sample by using the amplitude of a preset reference frequency and its multiple frequencies in the frequency spectrum of the vibration sample; identifying the effective local peak value of the discrete frequency spectrum sequence of each vibration sample; calculating the energy concentration degree feature and the energy distribution entropy feature of the vibration sample based on the effective local peak value; and finally evaluating the harmonic interference degree of the converter transformer at the current moment according to the energy concentration degree feature and the energy distribution entropy feature of each vibration sample. The scheme evaluates the harmonic interference degree of the converter transformer by using the vibration signal, thereby preventing the converter transformer from malfunctioning due to excessive harmonic interference.

This invention discloses a grain depot equipment operation status monitoring and green energy-saving control system, belonging to the field of intelligent grain depot control technology. It collects the instantaneous output frequency and total harmonic distortion (THD) of the variable frequency drive equipment, and simultaneously separates high-frequency noise components higher than the grain temperature change frequency. Based on the output frequency, it determines whether it falls into a sensitive frequency band, and performs causal correlation analysis between the high-frequency noise energy spectrum and the THD to calculate a reliability index. When the reliability exceeds a threshold, it determines that the temperature sampling value is contaminated by harmonics, discards the value, and generates a repaired temperature value based on the heat diffusion law of the grain pile using time-domain prediction or spatial interpolation. The repaired value is used for energy-saving control drive; when a temperature jump and an energy-saving control action are detected to be inversely related, the start / stop command of the variable frequency drive equipment is forcibly blocked. This invention, by identifying and suppressing harmonic interference from the variable frequency drive, avoids reverse control caused by temperature data jumps, ensuring the safety and reliability of energy-saving operation of the grain depot.

The application provides a Coriolis flowmeter inherent frequency detection method, device and electronic equipment. The embodiment uses a sine wave sweep excitation signal with continuous frequency and phase changes to detect the inherent frequency of the Coriolis flowmeter, and eliminates problems such as poor anti-interference performance and harmonic interference caused by using equal-interval square wave signals to measure the inherent frequency of the Coriolis flowmeter. With the vibration characteristics of the flow tube in the Coriolis flowmeter derived, the frequency and phase of the sine wave sweep excitation signal used to drive the flow tube to vibrate are continuously changed, so that the interference of the external excitation signal itself on the flow tube vibration can be directly offset or reduced, the signal-to-noise ratio (SNR) is greatly improved, for example, the SNR is increased from 1db when the flow tube is excited by using equal-interval square wave signals to at least 18db by the method provided in the embodiment, the inherent frequency of the Coriolis flowmeter is accurately detected, and the anti-interference performance is enhanced.

This invention provides an underdetermined mode identification method based on block term decomposition and adaptive kurtosis harmonic separation, belonging to the field of structural health monitoring and operating mode identification technology. The method acquires multi-channel vibration responses, calculates the covariance matrices under different time delays, and stacks them into a third-order tensor. Block term tensor decomposition is used to extract the time-domain autocovariance function sequence of each potential component. The natural frequencies and damping ratios of each component are initially estimated using local peak finding and logarithmic decay methods. The minimum truncation length is adaptively calculated based on the coupling relationship between period and damping ratio. Kurtosis values ​​are calculated for the truncated autocovariance sequence, and harmonic interference is eliminated based on a kurtosis threshold while retaining the true structural modes. Finally, mode shapes are extracted from the spatial block matrix of the retained components, outputting high-precision natural frequencies, damping ratios, and mode shapes. This invention can achieve accurate identification of dense modes and high-damped modes under complex operating conditions with severe underdeterminacy and harmonic interference, improving the robustness of operating mode parameter identification.

This application provides a method and apparatus for suppressing transformer losses. It extracts the electromagnetic harmonic characteristic layer, vibration state characteristic layer, and heat loss characteristic layer of a large transformer from historical multi-source operating data. Based on real-time acquisition of the current multi-source operating data and electromagnetic harmonic characteristic layer, it determines the harmonic interference mode of the large transformer. It generates a harmonic compensation current for the harmonic interference mode using the vibration state characteristic layer and heat loss characteristic layer. Based on the compensated multi-source operating data of the large transformer, it generates the measured harmonic spectrum and measured vibration spectrum under the current operating conditions of the large transformer to correct the control parameters of the frequency conversion modulation circuit in the large transformer, thereby suppressing transformer losses. Using the scheme of this application, transformer losses can be synergistically suppressed based on the transformer's vibration state and heat loss characteristics.

The application discloses a running control method and system of a direct drive motor, relates to the technical field of control of the direct drive motor, and realizes the real-time collection of three-phase voltage fluctuation data, extracts a harmonic spectrum in combination with frequency domain analysis, and preliminarily estimates a conduction delay and a dead zone compensation time; when low-order harmonic exceeds a standard, the dead zone compensation is increased to form preliminary optimization parameters; subsequently, neutral point deviation, common-mode voltage and three-phase asymmetry are evaluated through waveform simulation; finally, a swarm intelligence optimization algorithm is adopted to iteratively adjust a potential balance correction coefficient, the conduction delay, the dead zone compensation and a phase-to-phase timing offset angle, target timing parameters are obtained, and three-phase switching control instructions are generated and applied to a control system. In the high-power direct drive motor control, the application realizes the timing design of optimized switching action, effectively reduces harmonic interference, avoids system risks caused by potential imbalance, and improves equipment operation stability and reliability.

This invention provides a stator for a flat-wire motor. The stator has 3 slots per pole per phase, with the number of poles being an even multiple of 3. The windings form 2M layers within the slots, where M is an odd number greater than 2. The windings include three phases, each phase comprising two parallel branches. Each branch is formed by multiple U-shaped sub-conductors connected in series. Each phase winding includes multiple first conductor groups and multiple second conductor groups. The first conductor group includes three sub-conductors: a first conductor, a second conductor, and a third conductor. The second conductor group includes three sub-conductors: a second conductor, a third conductor, and a fourth conductor, or a first conductor, a second conductor, and a fifth conductor. The spans of the five conductors are K+1, K, K-1, K-2, and K+2, respectively. Each sub-conductor spans two adjacent layers, specifically the 2Nth layer and the 2N-1th layer. The second conductor groups are located on the Mth and M+1th layers, while the first conductor groups are located on other layers. This invention results in a compact stator structure, low manufacturing cost, minimal harmonic interference, and good operating performance.

The application provides a signal conversion system and method, and relates to the technical field of signal modulation.The signal conversion system comprises a diplexer, a receiving filter, a mixer, and a transmitting filter, wherein the transmitting filter comprises a harmonic filter; a receiving end of the diplexer, an input end of the receiving filter, an output end of the receiving filter, and an input end of the mixer are sequentially connected to form a signal receiving link; an output end of the mixer, an input end of the harmonic filter, an output end of the harmonic filter, and a transmitting end of the diplexer are sequentially connected to form a signal transmitting link; the signal receiving link extracts an input signal of an initial frequency, and transmits the input signal to the mixer; the mixer generates a difference frequency signal; the signal transmitting link extracts an output signal of a target frequency from the difference frequency signal, suppresses harmonic interference of the output signal, and feeds the output signal into the diplexer.The application at least solves the problem that it is difficult to simultaneously guarantee high isolation, signal purity, and reliability in the prior art.The application is suitable for a signal conversion scene.

The application relates to the technical field of power distribution network operation and control, and discloses an island detection method, system, equipment and medium based on low-frequency pulsation of reactive current, which comprises a flexible interconnection device suitable for low-voltage ride-through capability. In the method, a low-frequency sinusoidal disturbance signal with a frequency lower than the system fundamental frequency and avoiding harmonic interference is superimposed in the reactive current control instruction, a voltage response component with the same frequency as the disturbance is extracted by collecting a point of common coupling voltage signal, and the voltage response component is compared with a dynamic threshold value to determine an island state; when a voltage drop triggers low-voltage ride-through, the disturbance injection is maintained and the threshold value is adaptively adjusted; meanwhile, a multi-machine synchronization mechanism and a review process based on historical cases and operation rules are introduced, so that false judgments are effectively inhibited. The application does not require additional hardware, is compatible with the existing control architecture, and has the advantages of reliable detection, strong anti-interference capability and suitability for complex power grid working conditions.

The application discloses a self-adaptive frequency estimation method for inter-harmonic of self-controllable gateway electric energy meter, and belongs to the technical field of electric variable measurement. The application continuously samples a voltage signal, and the sampling frequency is three times of an integer multiple of a fundamental frequency; after band-pass filtering, the voltage signal is continuously grouped and sampled at intervals of one-third of a fundamental period; intermediate variables are calculated for each group of sampling data; then, a frequency domain compression factor reflecting only the fundamental frequency is directly extracted by using the mechanism that 1.5 times of inter-harmonic components are cancelled in factor operation; and finally, a convergence terminal value is obtained through adaptive iterative estimation, and the frequency is obtained through inverse cosine operation. The application integrates inter-harmonic cancellation and frequency information generation into the same link, breaks through the response speed bottleneck of the series structure of pre-filtering and phase-locked loop, and realizes fast and accurate estimation of the fundamental frequency under the interference of 1.5 times of inter-harmonic and dynamic load.

The application provides a transformer protection method and device based on a flow rate signal wavelet transform, and the method comprises the following steps: collecting a flow rate signal of insulating oil at a connecting pipe of a transformer; detecting whether the flow rate at a current time in the flow rate signal is greater than or equal to a preset flow rate threshold value; if the flow rate at the current time is greater than or equal to the flow rate threshold value, performing wavelet transform on the flow rate signal, and detecting whether the transformer is faulty according to the wavelet transform value of the flow rate signal; and when the transformer fault is detected, controlling the transformer to be powered off. According to the flow rate signal of the insulating oil at the connecting pipe of the transformer, whether the transformer is faulty is detected, the detection process is not interfered by signal transmission in a power system of the transformer, meanwhile, harmonic interference is not caused to the power system of the transformer, and the power system operation is not affected.

This invention discloses an external clock circuit for a radio frequency integrated circuit and its interference control method, as well as a walkie-talkie. The external clock circuit of the radio frequency integrated circuit includes a first crystal oscillator path with a first crystal oscillator and a second crystal oscillator path with a second crystal oscillator. The oscillation frequencies of the first and second crystal oscillators are non-integer multiples of each other. When frequency harmonic interference exists, the operating crystal oscillator can be switched from the first to the second crystal oscillator, essentially switching to a different operating system, thus eliminating interference caused by the first crystal oscillator. Furthermore, because the operating crystal oscillator is directly switched, the voltage control range of the crystal oscillator does not need to be considered. Compared with existing technologies, conventional crystal oscillators can be selected, resulting in lower costs and easier component selection. Moreover, due to the use of a dual crystal oscillator path, it can handle frequency harmonic interference received by walkie-talkies in various frequency bands and with different bandwidths, offering wide application range and high compatibility.

This invention discloses a sensorless composite sliding mode control method for mining permanent magnet synchronous motors (PMSMs). Addressing the technical bottlenecks of large speed fluctuations, delayed load disturbance compensation, and susceptibility to current harmonic interference in complex operating conditions, this method constructs an integral double-power sliding surface and a variable-gain reaching law, combined with a nonlinear extended state observer and a delay-compensated predictive current controller, to achieve sensorless control of the PMSM. The sliding mode control module employs a variable-gain design, enabling rapid convergence of the system state when far from the equilibrium point and smooth convergence as it approaches the equilibrium point, allowing the system to converge within a finite time under a given speed command. The observer module tracks internal and external disturbances in real time, incorporating the disturbances into the integral double-power sliding surface for feedforward compensation at the speed loop level. The current control module uses a digital delay compensation mechanism to predict the current at the next moment and calculate the optimal voltage vector using current sampling information, controlling the q-d axis voltage at the current loop level. This invention improves the dynamic disturbance rejection performance of the system under complex operating conditions, providing a new control system solution for the field of high-precision servo drives.

This invention belongs to the field of servo system control technology, specifically relating to a dynamic error compensation control method and system for a servo drive system. This invention effectively reduces torque fluctuations in the servo system during high-speed operation by calculating torque errors based on real-time data and generating compensation amounts. By correcting the three-phase current signals, it further improves the accuracy of current commands and reduces the impact of harmonic interference on system performance. Combining motor rotor acceleration and current ripple information, it comprehensively considers nonlinear disturbance factors and generates a total compensation strategy by superimposing compensation torque. Simultaneously, it adjusts the proportional gain and feedforward weight according to the dynamic mapping relationship between the rate of position change and the harmonic distortion rate, enabling the servo system to maintain optimal control performance under different operating conditions. Finally, all compensation results are injected into the feedforward and feedback channels, generating corresponding drive pulse signals based on space vector modulation, achieving efficient drive control of the servo system.

This invention provides a comprehensive electromagnetic interference simulation and analysis method for electronic test fields based on the UE4 engine, belonging to the field of electromagnetic interference analysis. Addressing the interference analysis needs of frequency-using equipment, this invention considers the near-field and far-field regions of the equipment model, establishing transmitter and receiver models based on the UE4 platform. Simultaneously, it considers static factors such as hillsides and trees, as well as dynamic factors such as weather and time, to establish a three-dimensional geographical environment model. The electromagnetic interference analysis method of this invention includes the finite-difference time-domain method, uniform diffraction theory, geometric diffraction theory, and ray tracing model, considering interference types such as fundamental frequency interference, harmonic interference, intermodulation interference, and spurious signal interference, and conducting interaction and interference analysis of equipment within the test field. This invention can comprehensively consider various factors of simultaneous testing in an electronic test field, define a set of frequency usage evaluation indicators, establish a management evaluation model, and achieve accurate modeling and evaluation of the current equipment layout and scheduling within the test field.

The application relates to a radio frequency transceiver circuit, a communication device and a wireless communication method, wherein the radio frequency transceiver circuit comprises a signal transmitting module, a signal receiving module and a harmonic elimination module, the harmonic elimination module is connected with the signal transmitting module and the signal receiving module; wherein the signal transmitting module is configured to transmit a first signal; the signal receiving module is configured to receive a second signal through the harmonic elimination module, wherein the second signal transmitted to the harmonic elimination module comprises a received signal from an antenna and a harmonic interference signal leaked from a transmitting link of the first signal to a receiving link of the second signal; the signal transmitting module is further configured to delay a time length and output an anti-interference signal to the harmonic elimination module according to the time length, so that the anti-interference signal and the harmonic interference signal are superimposed in the harmonic elimination module, and the harmonic interference signal is eliminated.