148 results about "Zero crossing" patented technology

The invention discloses an automatic anchor point searching and processing method for grid-connected test data of a photovoltaic inverter, and belongs to the technical field of automatic test of a power system. According to the method, a three-phase voltage and current signal output by a power grid simulator and an inverter power instruction signal are aligned through a high-precision time synchronization device; wavelet transform multi-scale noise reduction and moving average filtering combined preprocessing is adopted to improve the signal-to-noise ratio; identifying a voltage zero crossing point candidate set, a drop starting point candidate set and a recovery termination point candidate set based on a self-adaptive dynamic threshold value; transient energy characteristic verification is introduced for a voltage drop starting point; effective anchor points are confirmed through time window association of power instruction step changes. According to the method, the problems of low efficiency of manual key event point identification, misjudgment caused by noise interference, grid event and inverter response time sequence correlation missing and the like are solved, and the automation degree of test data analysis, anchor point positioning precision and control response time sequence analysis reliability are remarkably improved.

The invention discloses an accurate zero crossing point control method for a built-in relay of a large-current electric energy meter, which relates to the technical field of power electronics and intelligent metering and comprises the following steps of: receiving a power grid voltage digital signal, determining a voltage zero crossing point by comparing symbol changes of adjacent sampling values, establishing a phase corresponding relation between voltage and current, and calculating a current phase corresponding relation; generating current zero crossing point prediction data; when a relay switching instruction is received, the specific moment of the next current zero crossing point is calculated, and the control signal sending moment is determined; a relay driving control signal is sent, the actual action completion moment of the relay is collected, the deviation from the expected zero crossing moment is calculated, and the mechanical action delay time parameter of the relay is corrected. By predicting the current zero-crossing time and considering the mechanical action delay characteristic of the relay, accurate switching of the built-in relay at the actual current zero-crossing point is achieved, meanwhile, the self-adaptive adjusting capacity is achieved, the arc energy during large-current switching is reduced, the service life of the relay is prolonged, and the reliability of the electric energy meter is improved.

The invention relates to the technical field of voltage transformers, in particular to a voltage transformer real-time monitoring system based on broadband and edge calculation, which comprises the steps of collecting multiple paths of voltage transformer data, extracting peak values and zero cross points, comparing jump rising edge time differences, unifying time sequences, extracting extreme values and slope identification disturbance sections, and monitoring the voltage transformers in real time. Measuring amplitude continuous change to judge the offset trend, analyzing trend direction classification waveform fragments, and combining the three indexes to generate an operation state label. According to the method, a unified time sequence is constructed by comparing cross-channel jump rising edge time differences, multi-channel jump process alignment is achieved, the synchronous anomaly recognition capability is improved, the number of extreme values and the slope direction are extracted to recognize a disturbance dense section, continuous anomaly is judged by combining statistics of overrun, and the fluctuation trend is judged by tracking the deviation trend between extreme values. And based on the three-index combination classification operation state, the anomaly identification precision is improved.

The invention discloses an equipment working state recognition method based on a voiceprint recognition model, and relates to the technical field of industrial equipment operation state recognition. The equipment working state recognition method based on the voiceprint recognition model comprises the following steps: collecting operation audio waveform data of target equipment, extracting acoustic representation data containing parameters such as short-time energy, a frequency spectrum centroid, a spectrum flux, MFCC and a zero crossing rate, inputting the acoustic representation data into a pre-trained voiceprint recognition model to extract voiceprint feature representation vectors, and carrying out voiceprint feature representation on the target equipment; according to the method, the audio signal is divided into the frames, the acoustic features such as short-time energy, spectrum centroid, spectrum flux, MFCC and zero crossing rate are extracted, the inter-frame evolution relation is modeled in combination with the bidirectional neural network, and the attention mechanism is introduced to highlight the key frame segment, so that the real-time performance of the audio signal is improved, and the real-time performance of the audio signal is improved. The recognition capability of working conditions such as fuzzy state boundary or unobvious transition is effectively enhanced, and the time sequence analysis and state judgment precision is improved.

The invention provides a real-time electroencephalogram phase locking closed-loop stimulation method and system, and relates to the technical field of electroencephalogram signal processing. The method comprises the following steps: firstly, acquiring a cortex electrical activity signal and establishing a baseline statistic, then carrying out causal band-pass filtering on the signal, and carrying out sampling and holding substitution in a stimulation artifact window; setting an amplitude and a duration threshold based on the baseline, and performing phase judgment after conditions are met; estimating an average period through zero crossing and calculating an instantaneous phase; outputting a trigger instruction when the three-point crossing judgment is established; and outputting stimulation under the constraint of charge balance and a safety limit value, setting a minimum prohibition period and link abnormity suppression, and recording a hit rate and a response rate for quality evaluation. According to the method, through causal phase estimation, artifact isolation and a schedulable triggering mechanism, the high hit rate of non-stationary signal phase locking stimulation is achieved, and the safety and effectiveness of a stimulation system are ensured.

The invention discloses a power frequency phase adaptive acquisition device, and relates to the technical field of electric power signal measurement, the device acquires electric field data at a gap through an electric field sensor integrated on an edge shell, calculates electric field intensity fluctuation, and generates interference diagnosis information in combination with a preset interference determination threshold value; when the interference diagnosis information shows that effective interference exists, the electric field intensity variable quantity is calculated, a mapping model is established based on a proportionality coefficient obtained through an experiment so as to obtain zero crossing point offset, and the sampling trigger moment of a zero crossing point detection module is corrected; the clock synchronization module calculates a phase difference by taking the corrected trigger moment as a reference, dynamically adjusts a calibration frequency by combining a phase difference threshold value, and outputs a synchronized system clock signal; and the control system takes the synchronized system clock signal as a trigger signal, collects power frequency phase data according to a power frequency period, and stores the power frequency phase data to a database through a transmission unit, thereby realizing high-precision power frequency phase collection.

The invention discloses an Internet of Things flowmeter data compression sensing transmission optimization method and system, particularly relates to the field of low-power-consumption wireless communication networks, and is used for solving the problem of compressed sensing signal distortion caused by sampling time sequence misalignment in an LPWAN bandwidth limited environment. Constructing a local phase reference by extracting a pipeline vibration fundamental frequency component, and receiving a cloud synchronization reference timestamp alignment signal; fundamental frequency and third harmonic components are separated to calculate arrival time difference, and a phase-locked loop is triggered to dynamically adjust the phase of a sampling clock based on a pipeline material threshold value; after the stability of the zero crossing point time variance is verified, compressed sensing sampling is performed on the flow signal by adopting a phase synchronous clock, and an optimized compressed measurement value is generated and transmitted to the cloud through the LPWAN; through closed-loop cooperation of physical characteristics and a communication clock, complete capture of a signal sparse structure is guaranteed under a low-bandwidth condition, and cloud reconstruction precision is significantly improved.

The invention relates to the technical field of power system relay protection, in particular to a power transmission line single-end fault positioning method and system. The method comprises the following steps: taking an envelope zero crossing point of an initial transient traveling wave signal as an attenuation ending moment; taking the moment from the occurrence moment of the initial transient traveling wave signal to the attenuation ending moment as an analysis time window; taking the duration of the analysis time window as the attenuation duration of the initial transient traveling wave signal; taking the maximum energy peak value as a resonant frequency identification reference threshold value, searching whether the energy of other frequency peak values greater than the resonant frequency identification threshold value exists or not, and if so, judging whether the initial transient traveling wave signal has resonant interference or not based on the attenuation duration of the initial transient traveling wave signal; if yes, designing a filter for the frequency component, and filtering the initial transient traveling wave signal; and obtaining a fault positioning result of the power transmission line based on the filtered transient traveling wave signal. According to the invention, the single-end fault positioning precision is effectively improved.

The invention discloses a fault diagnosis method, device and equipment for an NPC three-level inverter and a medium, and relates to the technical field of inverter fault diagnosis, and the method comprises the steps: building a fault stator current analysis model according to a fault stator current change rule of the inverter; a fault phase and a fault bridge arm are extracted and positioned by using a sliding window averaging method; and calculating and setting a fault positioning reference value under an ideal condition, and comparing the fault positioning reference value with a fault positioning actual value under an actual condition to position a faulted IGBT (Insulated Gate Bipolar Translator). A fault stator current analysis model is established to simulate a set current change condition under an ideal condition, a fault positioning reference value is calculated, and whether an actual fault condition is consistent with a set ideal fault condition is distinguished by a deviation between the fault positioning reference value and a fault positioning actual value of an actual condition, and whether a fault is an inner pipe or an outer pipe is positioned. During calculation, a current mean value from a fault moment to a first zero-crossing moment is utilized, a fault IGBT can be positioned in a fundamental wave period, and fault diagnosis and positioning can be quickly and efficiently carried out.

The invention discloses a position-free sensing method for a joint module based on rotating speed estimation and virtual Z correction. The method comprises the following steps: firstly, acquiring three-phase current of a permanent magnet motor for a joint module, and acquiring d-axis estimated current of a current period based on a d-axis current model in combination with a state quantity of the permanent magnet motor in a previous control period; based on the d-axis estimated current, constructing a rotating speed estimator taking the d-axis estimated current error as a sliding mode surface to obtain the estimated rotating speed of the motor rotor; integrating the estimated rotating speed, and combining with the initial position of the rotor to obtain the estimated position of the motor rotor in the current period; at the same time, at the zero crossing point of the stator phase current, the estimation position is forcibly corrected to a predetermined electrical angle corresponding to the zero crossing point so as to eliminate the integral error. The invention aims to directly estimate the rotating speed without depending on any intermediate signal, and simulate the correction mechanism of a mechanical sensor to eliminate the estimation error, thereby realizing high-performance noise-free full-speed-domain position-free sensing control.

The invention relates to the technical field of magnetic shielding, and discloses a self-adaptive active adjustment type magnetic shielding device demagnetization circuit and device, and a control acquisition system, which are used for comparing a residual magnetism state with a preset expected value and generating a control instruction; the energy output identification system is used for outputting an alternating current degaussing signal according to the control instruction to perform degaussing, outputting an excitation pulse signal to perform residual magnetism detection, identifying a zero crossing point of the alternating current degaussing signal and realizing mode switching of degaussing and residual magnetism detection; and the magnetic shielding device is used for demagnetizing under the action of the alternating current demagnetizing signal and feeding back the residual magnetism state of the preset feature point under the action of the excitation pulse signal. The demagnetization is interrupted at the preset feature points in the demagnetization process, the real-time residual magnetism state is collected, and the demagnetization parameter at the next moment is adjusted after the real-time residual magnetism state is compared with the preset residual magnetism expected value, so that the problem of low efficiency due to the fact that the demagnetization parameter needs to be reset after the process is finished is solved, and the demagnetization efficiency and accuracy are greatly improved.

A switching modulation circuit generates a first control signal with a duty ratio. A delay circuit delays the first control signal to generate a second control signal. A zero crossing detector detects whether an output current of a DC / DC converter is smaller than a threshold in a rectification interval, and generates a third control signal. A monitoring circuit detects a reverse-flow possibility of the output current, and generates a fourth control signal. A delay time of the delay circuit is set shorter than the delay time of the zero crossing detector. When the reverse-flow possibility does not exist, and the third control signal has transitioned to indicate that the output current is smaller than the threshold, a driver circuit turns off both first and second switching elements. When the reverse-flow possibility exists, and the second control signal has transitioned from an ON state to an OFF state, the driver circuit turns off both the first and second switching elements.

The invention discloses a root mean square value RMS detection method and system, and belongs to the technical field of measurement and control. Wherein a to-be-detected voltage signal is preprocessed by the filter amplification circuit, a square wave signal synchronous with a sine wave zero crossing point is generated through the zero crossing comparison circuit, a signal period boundary is identified, and an integral number of complete and continuous signal periods are extracted in real time through the period detection module; the cycle information identified by the cycle detection module is transmitted to the data storage and processing module, meanwhile, the sampling signal of the high-speed ADC module is transmitted to the data storage and processing module, and sine wave data sampled by the high-speed ADC module is subjected to point-by-point square operation; the square values in a complete period are accumulated and summed, and an original sampling sequence is not stored; fIR digital filtering is carried out on the RMS values of continuous C periods through a digital filtering module; and the dynamic response performance of the system under different frequency bands is remarkably enhanced while the measurement precision is improved.

The invention relates to a two-way current smooth switching system and method without crossover distortion and a double-quadrant power supply, and the system comprises a signal setting unit, a dynamic bias ClassAB push-pull output unit, a feedback sampling unit and a control processing unit. According to the dynamic bias ClassAB push-pull output unit, static micro-conduction bias is provided for N-type and P-type power tubes in a push-pull output subunit through an internal bias subunit, and closed-loop control is combined, so that continuous and smooth transition can be realized when system output current is switched at a zero crossing point in the positive and negative directions, and the system stability is improved. And the problems of crossover distortion and switching dead zone existing in the traditional bidirectional power supply are thoroughly eliminated. According to the invention, high-efficiency, high-speed and distortionless bidirectional current output is realized, the system structure is simplified, and the system can be widely applied to the fields of high-precision test power supplies, battery simulators, servo drivers and the like.

The invention discloses a conductive slurry production control method and system based on multi-parameter cooperative control, and relates to the field of conductive slurry production, and the method comprises the steps: obtaining rheological characteristic data; according to the rheological characteristic data, a zero crossing point time difference between the excitation signal and the response signal is extracted, and a rheological phase angle is calculated; whether the rheological phase angle is located in a preset optimal dissipation interval or not is judged; if yes, the intrinsic relaxation time of the slurry microstructure is determined, and compensation frequency is generated according to the intrinsic relaxation time; the compensation frequency is used as a perturbation signal to be superposed to a driving voltage waveform of a driving motor, so that the stirring blades generate high-frequency vibration; and acquiring the deviation direction of the rheological phase angle, and dynamically adjusting the speed ratio of the revolution speed of the revolution shaft to the rotation speed of the rotation shaft under the condition of keeping the total power unchanged, so as to lock the rheological phase angle in the optimal dissipation interval. According to the invention, the yield and reliability of the electronic product can be effectively guaranteed.

The invention discloses a multi-frequency weak fault enhancement method based on fractional order resonance response atlas reconstruction, and the method comprises the steps: carrying out the noise reduction, trend term removal, phase compensation and modal decomposition of a mechanical vibration signal, determining a lag phase through a frequency sweep method for phase compensation, adjusting the phase of a same-frequency signal, reconstructing an effective component through the combination of a modal decomposition borrowing geometric method and a Pearson matrix, and carrying out the phase compensation. Constructing a nonlinear resonance model with historical memory; inputting the parameters into the same-direction coupling neuron model, dynamically updating and simulating transmission intensity change through synaptic weight, and solving response and step length; constructing a zero-energy coupling index based on a signal zero-crossing behavior, energy distribution and time-frequency analysis, wherein the time-frequency analysis comprises short-time Fourier transform and wavelet packet energy spectrum calculation to extract energy features; and iteratively optimizing parameters by using a quantum optimization algorithm, adjusting a rotation angle and preserving population diversity to prevent premature convergence, and outputting optimal parameters by taking a zero-energy coupling index as a target.

The invention discloses a method and a system for optimizing a metering front end of an intelligent electric meter. The method comprises the following steps of: setting an anti-aliasing network with a near-linear phase at the front end of a metering channel and synchronously sampling; determining a range switching window based on zero crossing or a preset voltage change rate, executing automatic range switching in the window, and performing overlapping sampling and digital splicing on samples before and after switching; determining a rectification conduction empty window based on the rectification conduction prediction, suspending sampling in the empty window, and compensating a missing sample; injecting a reference signal into the channel at the calibration injection window, obtaining a correction coefficient according to response, and performing online correction; the three types of windows are not overlapped and are uniformly scheduled by a synchronous time sequence; and completing power and energy calculation according to the corrected voltage and current sequence. The system comprises an anti-aliasing network unit, a range control unit, a rectification conduction detection unit, an air window door control unit, an injection and online correction unit, a time sequence synchronization unit, a metering calculation unit and the like. According to the invention, low-distortion, wide-range and consistent metering output can be realized in practical application.

The invention discloses a voltage circuit breaker AC open circuit control method and device, and relates to the technical field of open circuit control, and the method comprises the following steps: obtaining a target waveform sequence of a target AC circuit, and obtaining a fundamental component and a higher harmonic component through frequency domain decomposition, so as to extract current waveform features; constructing a zero-crossing prediction model based on current waveform characteristics, dynamically correcting the prediction model in combination with higher harmonic components and load asymmetry characteristics, and generating a preliminary breaking moment candidate interval; determining a final on-off moment by combining the instantaneous power direction reversal point and an arc maintenance energy threshold value; and triggering the circuit breaker to act at the final breaking moment, and dynamically adjusting the contact separation speed based on the residual arc energy until the arc energy is attenuated to a safety value. According to the method, the zero-crossing prediction model is constructed by extracting the current waveform characteristics, the contact separation strategy is dynamically corrected, and the problems of arc extension and equipment damage of a traditional circuit breaker under the condition of harmonic distortion or sudden disturbance are solved.

The invention relates to a development type single-phase earth fault real-model test device and a control method, the development type single-phase earth fault real-model test device is connected in a whole power grid and comprises a fault intelligent generation module, and the fault intelligent generation module comprises a dynamic resistance simulation unit and an intelligent switching control system. And the intelligent switching control system is used for controlling the access resistance value and the access time of the resistor in the dynamic resistance simulation unit. The dynamic resistance simulation unit structure is of a three-level resistance topology and is combined with a mixed switching matrix of a vacuum relay and a solid-state relay. The intelligent switching control system is used for realizing the switching of the resistor at a current zero crossing point, the intelligent switching control system comprises a low-power-consumption control circuit and a signal acquisition circuit, the structure is matched with the control method, the continuous or step dynamic change of the grounding resistor can be accurately simulated, the problem of transient impact in the resistor switching process is solved, and the stability of the grounding resistor is improved. And a standardized and quantifiable test platform is provided for performance assessment of power distribution network fault handling equipment.

The invention discloses an electrical energy consumption and mechanical load coordinated instrument dynamic calibration system, and relates to the technical field of instrument calibration, the system comprises a diagnosis module for receiving original data streams of an electrical side and a mechanical side, and identifying segments to be optimized by calculating a symbol consistency rate and a zero cross alignment error; the robust symbol division module performs symbol state judgment by using a dynamic dead zone and a double-domain hysteresis comparator, and outputs smooth symbol segments and a switching delay table in combination with a finite state machine; the signed channel reconstruction module executes phase micro-shift and amplitude reconstruction based on the switching delay table, and outputs the signed channel after electrical side optimization; the write-back and closed-loop module obtains positive and negative power calibration parameters through bipolar bucket separation and robust linear regression, and writes back to the instrument after event-level energy closed verification to form closed-loop verification. According to the method, the instrument calibration precision and reliability under the dynamic working condition are effectively improved.

The invention relates to the technical field of fault prediction, in particular to an online fault diagnosis method and system for railway axle counting equipment, and the method comprises the following steps: collecting an original analog voltage signal of an axle counting sensor on line in real time, sampling a wheel passing signal each time, obtaining an original voltage signal sample, and calculating the fault of the axle counting sensor; time axis stretching transformation is carried out on each original voltage signal sample, and a standardized waveform sequence is established; according to the method, the original analog voltage signal of the axle counting sensor is subjected to successive sampling and standardization processing, so that the comparability of the waveform in the time dimension is improved, and the micromorphological feature vector is constructed by combining a plurality of waveform features such as peak symmetry, rising edge slope, falling edge slope, oscillation attenuation rate after zero crossing, integral area and the like; fine-grained information reflecting the health state of the sensor is modeled.

The invention discloses an output voltage compensation method, device and assembly of a dual-active bridge converter. The method comprises the steps of obtaining a first voltage and a first current of a grid-side power supply and a second voltage and a capacitance value of an integration module; according to the zero crossing point moment of the first voltage, an insertion beat compensation starting point of the output voltage of the energy storage output module is determined; the insertion beat compensation starting point is a target moment after the zero crossing point moment; according to the first voltage and the first current of the network side power supply, the second voltage and the capacitance value of the integration module and the switching period of the switching module of the secondary side bridge arm circuit, the voltage compensation amount of an insertion beat compensation end point is determined; according to the voltage compensation amount of the integration module at the end point of the beat insertion compensation, determining beat insertion time; and controlling the conduction state of the secondary side bridge arm circuit at the insertion time at the insertion compensation starting point so as to adjust the average value of the output voltage of the energy storage output module to be continuous before and after the zero crossing point moment of the first voltage. According to the technical scheme provided by the embodiment of the invention, the oscillation of the output voltage is improved.

The invention relates to the technical field of wind power generation control, and discloses a self-adaptive high-power-density permanent magnet motor control method and system, and the method comprises the steps: monitoring a motor current waveform zero crossing point time sequence in real time, and taking the occurrence frequency of a time sequence abnormal event as a recognition basis of a system stress state; when the stress state is identified, d-axis current is instantly injected to form flexible electromagnetic damping, q-axis current output is synchronously limited to reserve safety margin, a current distortion signal is converted from a control error to a system state messenger, response is carried out in a cooperative mode of combining flexible suppression and active protection, and the safety margin is reserved. The problems of overheating and mechanical fatigue accumulation caused by excessive compensation when a traditional control mode deals with disturbance are avoided, the control system obtains the irritability self-protection capacity, and the operation reliability of the wind generating set under the uncertain working condition is improved.

The invention provides a method for improving PT residual voltage frequency measurement accuracy based on rotation vector characteristics, and relates to the technical field of generator set rotation speed measurement. The method comprises the following steps: acquiring a three-phase voltage alternating current signal through a generator end PT; processing the three-phase voltage signal to obtain projections of a voltage rotation vector on alpha and beta static coordinate axes; frequency characteristics are extracted based on projection and voltage amplitude and can be realized through direct calculation or a phase locking link; performing low-pass filtering on the frequency characteristic direct current quantity; a generator speed is calculated based on the filtered frequency and provided to a governor. According to the method, the limitation that a traditional PT residual voltage method only depends on zero crossing point information is broken through, frequency characteristics are extracted through a complete voltage sequence, alternating current signal filtering distortion is avoided through direct current filtering, high measurement precision and high anti-interference capacity can still be kept under the low-speed working condition, the problems that an existing speed measurement method is insufficient in precision and weak in anti-interference capacity are effectively solved, and the method is suitable for popularization and application. And reliable guarantee is provided for safe and stable operation of a unit.

Methods for switching the power source supplying an alternating current (AC) electrical load from a first AC power supply to a second AC power supply comprising: (a) determining, during a time period, the zero voltage crossings of at the first and second AC power supplies; (b) estimating for a future time period, based on information obtained in said determining step (a), the times at which a series of future current zero-crossings of said AC load and at least the current zero-crossing of the second power supply; (c) based on said estimating step (b), determining whether during said future time period the time of said zero-crossing of said load current and the zero-crossing of the second power supply are within about 0.1 microseconds of each other; and (d) for a time period during which said zero crossings are estimated to be within 0.1 microseconds of each other, switching said load to said second power supply at said time at which said zero crossings are estimated to be within 0.1 microseconds of each other, wherein said switching: (i) uses a solid-state switching system and microprocessor-based control system for actuating said solid-state switching circuit; and (ii) accounts for any known actuation delay between the actuation signal from said microprocessor and the occurrence of said switching.

This invention discloses an AC circuit breaker control method and device, relating to the field of circuit breaker control technology. The method includes the following steps: acquiring the target waveform sequence of the target AC circuit and obtaining the fundamental and higher harmonic components through frequency domain decomposition to extract current waveform features; constructing a zero-crossing prediction model based on the current waveform features, and dynamically correcting the prediction model by combining the higher harmonic components and load asymmetry characteristics to generate a candidate interval for the initial breaking time; determining the final breaking time by combining the instantaneous power direction reversal point and the arc sustaining energy threshold; triggering the circuit breaker operation at the final breaking time, and dynamically adjusting the contact separation speed based on the residual arc energy until the arc energy decays to a safe value. This invention solves the problems of arc extension and equipment damage in traditional circuit breakers under harmonic distortion or sudden disturbances by extracting current waveform features to construct a zero-crossing prediction model and dynamically correcting the contact separation strategy.

The invention relates to the synchronization between at least two data acquisition devices of an online monitoring system for an electrical distribution network, each located at a known point A or B of the network and configured to detect high-frequency events during the data acquisition phases. According to the invention, during a first phase of estimating the period of the electrical signal passing through the network, each data acquisition device samples the electrical signal and deduces an estimate T' or T' of the period of the electrical signal by detecting the zero-crossing times of the sampled signal, with local timestamping by means of a timestamping system associated with each data acquisition device.One of the devices then sends an information signal at a first detection instant t, with a local timestamp, of a new zero crossing of the sampled signal, and activates a data acquisition phase at a first instant T separated from the first detection instant by a duration corresponding to the first estimate T' of the electrical signal's period. The time of reception of this signal by the other device is also recorded using a local timestamp method. After a time equivalent to half of the second estimate T' of the electrical signal's period following the reception time, this other device activates a high-frequency event acquisition phase for several successive cycles of predefined duration, at a second activation instant t determined locally, which corresponds to a second detection instant of a new zero crossing of the sampled signal locally.Next, we can determine a synchronization difference Δt between two high-frequency events acquired, in a given cycle, by the two data acquisition devices, by calculating the difference between the second activation instant ty and the first activation instant t.

The invention relates to an atomic magnetic resonance measuring device, in particular to a method and equipment for stabilizing laser frequency of a CPT magnetometer. Comprising the steps that firstly, the output frequency of a laser is preliminarily adjusted to be close to the CPT resonance frequency of alkali metal atoms, and after an axial magnetic field is applied, laser is shaped into a light beam containing left-handed and right-handed circular polarization components and enters an atomic gas chamber; the double-channel detector synchronously collects light intensity signals of two types of polarization components, error signals are generated through differential normalization processing, and the feedback controller generates control signals according to the signals and adjusts the frequency of the laser so that the frequency of the laser can be locked at the zero crossing point of the error signals. Errors caused by environmental disturbance are effectively suppressed, the robustness and precision of laser frequency locking are remarkably improved, and the method is suitable for precise atom sensing systems with high stability requirements such as a CPT magnetometer and the like.

The invention discloses an intelligent equipment linkage control method and system based on video content analysis, and relates to the field of video content analysis, and the intelligent equipment linkage control method based on video content analysis comprises the following steps: S1, obtaining video parameters, and carrying out the preprocessing; s2, pixel motion vectors are extracted, and a time sequence motion field is formed; s3, extracting a pixel dominant motion information set, calculating an average speed value, and generating a time sequence speed parameter set; s4, performing zero crossing point identification on the time sequence speed parameter set, and generating a time sequence displacement control signal; and S5, sending the time sequence displacement control signal to the external intelligent equipment, and driving the external intelligent equipment to generate physical motion with the video content by adopting the displacement signal. According to the method, by introducing preprocessing means such as multi-scale image analysis, resolution compression and graying conversion, key information is efficiently and accurately extracted from the video, and the precision and efficiency of subsequent analysis are improved.

Methods for switching the power source supplying an alternating current (AC) electrical load from a first AC power supply to a second AC power supply comprising: (a) determining, during a time period, the zero voltage crossings of at the first and second AC power supplies; (b) estimating for a future time period, based on information obtained in said determining step (a), the times at which a series of future current zero-crossings of said AC load and at least the current zero-crossing of the second power supply; (c) based on said estimating step (b), determining whether during said future time period the time of said zero-crossing of said load current and the zero-crossing of the second power supply are within about 0.1 microseconds of each other; and (d) for a time period during which said zero crossings are estimated to be within 0.1 microseconds of each other, switching said load to said second power supply at said time at which said zero crossings are estimated to be within 0.1 microseconds of each other, wherein said switching: (i) uses a solid-state switching system and microprocessor-based control system for actuating said solid-state switching circuit; and (ii) accounts for any known actuation delay between the actuation signal from said microprocessor and the occurrence of said switching.