215 results about "Wave period" patented technology

The invention relates to a pulse-width modulation (PWM) output method for solving the problem of nonuniform heating of a bridge arm switch of a single-phase full-bridge inverter circuit. The PWM output method is characterized in that two bridge arms use the modulation wave period T as an interval for alternately outputting PWM waves and square wave voltage. The problem of nonuniform heating caused by great work frequency differences of two bridge arm switches is solved, the temperature of an overheat switch is obviously reduced, insulated gate bipolar translator (IGBT) power switch device faults caused by overheat is effectively overcome, the reliability of a switch device is favorably improved, and the service life is prolonged.

The invention provides a balanced photoelectric detection method and system capable of eliminating beat interference between signals. Light carrier waves and light OFDM signals in received SSB-OOFDM signals are separated during a partial wave period, the light carrier waves and the light OFDM signals are coupled again through a 3dB 2*2 optical coupler, appropriate dependency is introduced between the light carrier waves and the light OFDM signals, photoelectric balanced detection is conducted on the coupling output, the two paths of signals are converted into electrical signals and are subtracted in the electric field to obtain output electric OFDM signals, the electric signals only have OFDM radio-frequency signal parts, and no SSBI interference is introduced. According to the balanced photoelectric detection method and system capable of eliminating beat interference between the signals, receiving of SSBI and direct current components can be achieved, the necessity of setting frequency band protective intervals due to the SSBI is theoretically eliminated, and the frequency spectrum utilization efficiency of a SSB-OOFDM system can be improved.

This invention presents a method for computing Instantaneous Frequency by applying Empirical Mode Decomposition to a signal and using Generalized Zero-Crossing (GZC) and Extrema Sifting. The GZC approach is the most direct, local, and also the most accurate in the mean. Furthermore, this approach will also give a statistical measure of the scattering of the frequency value. For most practical applications, this mean frequency localized down to quarter of a wave period is already a well-accepted result. As this method physically measures the period, or part of it, the values obtained can serve as the best local mean over the period to which it applies. Through Extrema Sifting, instead of the cubic spline fitting, this invention constructs the upper envelope and the lower envelope by connecting local maxima points and local minima points of the signal with straight lines, respectively, when extracting a collection of Intrinsic Mode Functions (IMFs) from a signal under consideration.

The invention provides a method for eliminating chopping waves and ripple waves and an analogue-digital conversion circuit for realizing the method. The method comprises the following steps of: carrying out two times of sampling on signals in a chopping wave period at an interval which is one half of time of the chopping wave period; and carrying out integration and summation on two times of sampling values so as to keep useful signals and eliminate residual ripple wave signals in the chopping waves. The signal amplification and analogue-digital conversion circuit comprises a chopping wave amplifier and a sigma-delta analogue-digital converter which is cascaded behind the chopping wave amplifier. A switching structure which is embedded into the sigma-delta analogue-digital converter is adopted and an analogue addition function of a first-grade integrator in the analogue-digital converter can be used for carrying out first-order reshaping (voltage summation) on the residual ripple waves of output signals of the chopping wave amplifier, so that the ripple wave amplitude is reduced and influences on the conversion precision of the analogue-digital converter is weakened. The circuit does not need an analogue low-pass filter between the chopping wave amplifier and the analogue-digital converter, so that the power consumption and the area are saved and the design of the circuit is simplified.

The invention provides a comprehensive platform with a floating type full concrete structure with an underwater storage tank for well drilling, well workover, production, public use and household. The platform has 12 different modes, and each mode consists of a liquid storage system, supporting legs, an upper facility and an anchoring leg positioning system. The platform not only has a series of characteristics and advantages, such as SPAR platform heavy draught, small waterplane area, higher center of buoyancy than center of gravity, platform natural period more than the wave period corresponding to once-in-a-century significant wave height and the like, has the function of liquid (oil) storage, and maintains the draught depth of the platform in the process of oil storage and discharge operation unchanged. The platform matched with a single-point or multi-point anchoring device can form a complete development system for production, well drilling, well workover, storage and outward transportation of offshore petroleum and natural gas; the platform not only can be used for development of an offshore large and deepwater oil-gas field with long production life, but also can be used for a small and deepwater oil-gas field with short production life, in particular the development of a marginal oil-gas field. After development of the oil-gas field is finished, the platform can be transferred and reused conveniently.

The invention provides a method for measuring the frequency of a power system, which is mainly applied to a power system. The method comprises the steps of sampling input signals at intervals to obtain discrete equally-spaced sampling points; carrying out direct current filtration on the equally-spaced sampling points; accumulating the discrete points slightly exceeding a fundamental wave period point number by taking a point near a peak value as a starting point for the filtered data, if the accumulated sum is zero, recording the last point, and if the accumulated sum is not zero, sequentially reducing from the last point until the accumulated sum reverses, and recording the point enabling the accumulated sum to reverse; and determining the period of a measured signal through the recorded point, the sampling interval number between the point and the starting point and the reversed accumulated sum to obtain a frequency value. According to the method, the theoretical basis is that an upper integral of a trigonometric function on a fundamental wave period is zero, higher harmonics are not needed to be filtered, the anti-interference is strong, the realization is simple, and the accuracy, the reliability and the rapidness of fundamental wave frequency measurement are improved.

The invention discloses a combined wave power generation device provided with oscillating buoys as well as a measurement and control system of the device. The power generation device and the measurement and control system are included, multiple groups of hiding platforms can be arranged according to the installed capacity, and multiple oscillating buoys are mounted on each hiding platform. On the basis of a traditional wave power generation device provided with oscillating buoys, a hydraulic energy storage system, a tide level adaptation system and a wave detection system are designed. The hydraulic energy storage system controls energy storage and energy release of energy accumulators to drive a power generator to generate power according to the upper limit and the lower limit of energy storage pressure of an energy accumulator group in combination with real-time wave information. According to the device, multi-point energy absorption replaces traditional single-point energy absorption, immediately captured wave energy can be maximized, the measurement and control system can cooperate with the combined wave power generation device provided with the oscillating buoys, multiple defects of shorter wave period, small wave height and low energy flux density of national offshore wave energy resources can be effectively overcome, and maximum-efficiency conversion of wave energy to power and maximum-efficiency utilization of the power are realized.

The invention discloses an ocean wave parameter extraction method based on an SFS technology. According to the Lambertian scattering law, relations between the relative echo intensity and the incident angle, the direction slope and the distance slope are derived, the SFS technology and transformation formulas of polarization direction angles caused by the direction slope and the distance slope of the ocean surface are combined to solve slope values of pixels of the ocean surface, and a direction slope spectrum and a distance slope spectrum are obtained respectively by using fast Fourier transform. Spectral peak positions are searched, wave number vector information is acquired, 180-degree ocean wave direction blur is eliminated, ocean wave propagation directions are determined, the wavelength is calculated according to relations between the wave number and the wavelength, the ocean wave period is solved through ocean wave dispersion relations, and the significant wave height is calculated by the average slope and the wavelength. According to the ocean wave parameter extraction method, ocean wave spectrum inversion can be performed without a modulation transfer function, parameters such as the ocean wavelength, the period, the significant wave height and the ocean wave direction can be extracted, and the method is applicable to images acquired by high-frequency radars.

The invention relates to a signal extracting method, and belongs to the field of dynamic balance measurement. An extraction method of an unbalanced signal for the dynamic balance measurement is characterized by comprising the following steps of: (1) conditioning and filtering a vibration signal transmitted by a vibration sensor and performing fast Fourier transform (FFT) operation on the filtered signal to acquire signal amplitude values at different frequency points, searching a signal component near the frequency of the unbalanced signal in an operation result, judging whether the signal has near-frequency interference or not, and if the signal has the near-frequency interference, estimating a beating wave period of a beating wave phenomenon which occurs after the interference according to an FFT result; (2) extracting the unbalanced signal by using data in the beating wave period as a sample by a sine approximation method; and (3) if the signal does not have the near-frequency interference, extracting the unbalanced signal by a full period data sampling-based orthogonal correlation method. By the method, the stability and the reliability of the dynamic balance measurement are improved, the measurement range of a dynamic balance measurement system is enlarged, and the measurement accuracy of the system is improved.

A significant wave height and wave period parameterization method comprises the following steps that 1. buoy data of five fixed buoy stations of JMA, satellite height meter significant wave height hs provided by AVISO and 1 degree * 1 degree reanalysis grid point data of sea surface 10 m wind speed are obtained, wind speed at observed height is converted into 10 m height wind speed U10, average wave height and an average wave period are converted into significant wave height hs and a significant wave period Tp; 2.based on a data mining technology, according to the proportion of 2 : 1 : 1, the five fixed buoy stations and data of height meter grid point information are divided into a training set, a verifying set ad a testing set, and data obtained through a 44008 station are only divided into a verifying set and a testing set according to the proportion of 1 : 1; and 3. the significant wave height parameterization method is established and verified.

The invention provides a real-time monitoring system for the fatigue of an automobile driver based on a human respiration signal, and relates to a human respiration signal acquisition and processing device and a respiration signal processing method. A hardware part of the system comprises a power supply module, a respiration signal acquisition module, a microprocessor module and a warning module, wherein the respiration signal acquisition module comprises a waistband made through a variable polar pitch type capacitive sensor, and a corresponding circuit. The respiration signal is processed through the following steps: first, applying an empirical mode decomposition (EMD) to remove a noise signal, and then, performing time-domain analysis on the signal, calculating the respirator wave period and amplitude and the yawn frequency, judging the fatigue condition of the automobile driver according to the monitored change in value, and warning in time.

The invention discloses an inverter parallel system control method based on pulse duration modulated wave reconstitution. The method includes the following steps that 1 the frequency of pulse duration modulated waves is calculated according to the requirement of an inverter, and the frequency is set as the control period frequency of a master controller and modulated wave frequency of slave controllers; 2 signals of voltage, electricity, and the like of the inverter are acquired through a signal acquiring unit and signal filtering is carried out; 3 comparator parameters of the space vector modulated wave are calculated by a master control unit in a pulse duration modulated wave period; 4 the comparator parameters and synchronizing signals are encoded by a signal programming unit and broadcast to all the slave controllers in a serial mode; 5 the comparator parameters and synchronizing signals are received and encoded by the slave controllers, and signal reconstitution pulse duration modulated wave signals encoded serve as driving signals of power devices. Synchronism and consistency of the driving signals of each power device are guaranteed by the control method based on the pulse duration modulated wave reconstitution inverter parallel system. Zero-sequence circle current of the inverter in parallel is essentially removed and reliability of the system is improved.

The invention discloses an interharmonic detection method for eliminating interference caused by fundamental waves and harmonic waves to interharmonic detection. The method comprises the following steps: establishing an electric power system model, when detected signals of an electric power system only have fundamental wave and harmonic wave components, performing truncation analysis on continuous signals through a method of adding rectangular windows of M fundamental wave periods, and obtaining parameters of interharnomic waves; when the detected signals of the electric power system only include a combination of the fundamental waves, the harmonic waves and interharnomic waves with a single frequency, taking values of a frequency spectrum graph from endpoints of sidelobes, for reflecting frequency spectrum features of the inerharnomic waves; and when the fundamental waves, the harmonic waves and multiple interharmonic waves exist in the detected signals of the electric power system, constructing a new function by use of features of the frequency spectrum graph and the feature that the attenuation speeds of main lobes are faster relative to adjacent sidelobes and are successively mitigated downwards so as to enable the attention speeds to be faster. The method has the advantages of convenient realization, simple analysis and high precision and is an accurate and practical harmonic analysis algorithm. An effective method is provided for harmonic detection and analysis in the electric power system.

The invention discloses a phase sequence identification adaptive method applied to an electric energy quality management device. The method comprises the steps of (1) setting the number of sampling fundamental wave periods SAM_N for phase sequence judgment, and recording sampling location numbers of line voltage US12, US23 peaks in each fundamental wave period; (2) calculating the difference of the two sampling location numbers at the end of the period number SAM_N, and respectively accumulating a positive ordinal number POS_N and a negative ordinal number NEG_N based on a range to which the difference belongs; (3) judging an incoming line voltage phase sequence based on values of the positive ordinal number POS_N and the negative ordinal number NEG_N; (4), maintaining a conventional algorithm when the phase sequence is positive, interchanging voltage sampling values of the two lines and taking the negative when the phase sequence is negative so as to convert the negative phase sequence into the positive phase sequence; and (5) calculating a compensation target value correctly through interchanging control strategies when the phase sequence is negative so as to realize correct compensation management of the electric energy quality management device. According to the invention, the incoming line voltage phase sequence is judged in an adaptive manner, and the control strategy is adjusted automatically, so that the electric energy quality management device is enabled to have no requirements on an incoming line connection method and the phase sequence, and the adaptability of the device is enabled to be enhanced.

The invention discloses a switching tube open-circuit fault diagnosis method of an open winding electrically-driven conversion system, applied to a twin inverter-open winding motor system. The methodcomprises the following steps: step 1, monitoring a value of sum d of three-phase current per unit average values in real time, wherein d=Da+Db+Dc, and the formula is represented in the specification,wherein <> refers to solving the current average value in a single fundamental wave period, Ia, Ib and Ic are three-phase stator current; step 2, comparing the value of the sum d of the three-phase current per unit average values with a threshold value k, if d is greater than -k and less than k, an fault is not existent, if d is greater than k, the switching tube eta 12 or the switching tube eta21 has an open-circuit fault, and if the -k is greater than the d, the switching tube eta 11 or the switching tube eta 22 has the open-circuit fault, wherein eta=a, b, c. With the method provided by the technical scheme of the invention, aiming at an open winding motor-common DC bus twin inverter system, compared with the prior art, the method has the following advantages: having no need of mounting additional hardware, being capable of accurately identifying location of a fault switch under a situation where any switching tube is open-circuit, and consequently providing strong guarantee for implementation of redundancy control.

The invention discloses a nondestructive inspection device for a wire rope. In addition to an excitation component, a sensor component and a data processing module, the nondestructive inspection device also comprises an angle encoder, wherein the sensor component is a sensor differential array composed of n pairs of sensors; the n pairs of sensors are distributed on two rings having equal radii; the axes of the two rings coincide; the distance between the two rings is a strand wave period length of a wire rope; the sensors on each ring are distributed at equal angles; the sensors belonging to one pair are distributed on the same angle positions of the two rings; the sensor differential array is positioned in the excitation component; the wire rope to be inspected is penetrated through the sensor differential array and is in contact with a roller wheel of the angle encoder; the data processing module performs differential operation on collection signals of each pair of sensors to obtain n differential results; and if a peak exists among the differential results, the wire rope is considered as having a damage defect. According to the invention, strand wave noise interference can be effectively eliminated.

The invention discloses a selective harmonic wave extracting method, which comprises the following steps of: (1) acquiring load current, and keeping the quantities of sampling points at every fundamental wave period of the load current equal; (2) performing band-pass filtering processing on the load current based on closed-loop control to obtain each specified subharmonic component; and (3) overlapping each secondary harmonic component specified by a signal to be tested. By combining a phase-locked loop technology of a fixed point quantity, the selective harmonic wave extracting method with high performance is provided for a system which requires a fixed sampling point quantity; and under the condition of fluctuation of fundamental wave signal frequency, selective resonant wave extraction can be realized at high accuracy, occupied control system resources are reduced relatively, and high stable precision is achieved.

The invention discloses a carrier phase-shifting pulse width modulation method. The carrier phase-shifting pulse width modulation method is used for adjusting the phase of a triangular carrier. In the operation process of PWM, the computational process, a computational method and the comparison logic are not changed on the basis of traditional PWM, phase changes are periodically carried out on the triangular carrier, a controller carries out phase shifting with the odd number times of 180 degrees on the phase of triangular carrier at intervals of a half of a fundamental wave period or one of odd-number parts of a half of the fundamental wave period, and even harmonic in a PWM waveform can be eliminated theoretically. The carrier phase-shifting pulse width modulation method is wide in range of application, free of complex computation, easy to implement, suitable for both single-phase application and multi-phase application, suitable for PWM communication modes such as SPWM and SVPWM, and applicable to engineering popularization.

The invention provides a Doppler spectrum center frequency estimation method based on a frequency shift iteration. In the method, a spectral moment method estimation frequency shift is taken as an initial value; an integral interval is changed step by step so as to carry out iterated integral; the spectral moment method estimation frequency shift is used in each iteration till that a final frequency shift result convergence is performed; the result is taken as an optimum estimation value of a Doppler spectrum center frequency. Compared to a traditional spectral moment method, by using the method of the invention, an effect of estimating a center frequency by using the frequency shift iteration method is good, a mean absolute error and a root-mean-square error are small and estimation precision of the method is not restrained by a frequency shift resolution. The method is used in a Doppler wave observation radar so that ocean wave parameters of an accurate effective wave height, an average wave period and the like can be obtained.

The invention discloses a high-precision harmonic analysis method of sampling data synchronization, which is suitable for the field of power grid harmonic analysis and can realize accuracy computation of frequency, amplitude and phase of a power grid signal. The technical scheme of the invention is as follows: 1, a quadratic polynomial reverse interpolation method for accurately determining a fundamental wave period ensures that the computing precision of the fundamental wave period is improved by 2 orders of magnitude (reaching 1.51*10<-7> percent); and 2, a radial primary function interpolation method used for synchronizing nonsynchronously-sampled data ensures that synchronization data errors subjected to radial primary function interpolation are improved by 3-4 orders of magnitude (reaching 1.1*10<-9> percent). The invention has the advantage that the computing precision of harmonic parameters (amplitude and phase) on the basis of synchronization data is improved by 4-5 orders of magnitude.

The invention provides a dynamic phasor measurement system of a phasor measurement unit (PMU), and a measurement method thereof. The system comprises a current and voltage input module, a satellite receiver, a calculation module, a communication module and a memory module. The calculation module is connected with the satellite receiver, the communication module, the memory module and the current and voltage input module. According to the invention, dynamic phasors are measured by use of a three-quarter fundamental wave period dynamic phasor measurement algorithm so that the conflict between computational complexity and real-time performance in dynamic phasor measurement is solved, the dynamic phasors are rapidly and accurately measured, the measurement performance of the PMU can be improved, and assistance is provided for large-power-network analysis and control.

The invention discloses an ocean wave buoy based on a parallel piezoelectric type six-dimensional acceleration sensor. The ocean wave buoy comprises a buoy body, a sensor system and a control system,wherein the control system arranged in the buoy body integrates wave acceleration information, wind speed information, wind direction information and azimuth angle information which is sent by an electronic compass, separately processes the characteristics of waves at the position of the ocean wave buoy body and meteorological data to calculate the main wave direction, the wave height, the wave period, the actual wind direction and the actual wind speed, and sends the calculated main wave direction, the wave height, the wave period, the actual wind direction and the actual wind speed to a monitoring system on a user side through a communication module. By means of the ocean wave buoy, the technical problems that ocean waves are observed can be solved, and the limitations in the prior art can be overcome; the wave characteristics, such as the wave height, the wave period and the wave direction, of the ocean waves and the meteorological factors, such as the wind speed and the wind direction, can be observed.

A peak voltage detector circuit detects a peak voltage of an input voltage. The input voltage is input into a first input terminal of a comparator. A counter circuit counts up a counter value in synchronization with a first clock signal, when a signal output from the comparator is in a first state. The counter circuit counts down the counter value in synchronization with a second clock signal. A digital-analog conversion circuit outputs an output voltage corresponding to the counter value, and the output voltage is input into a second input terminal of the comparator. The first clock signal has a wave period shorter than that of the second clock signal.

To detect actual deterioration from digital pulse signals output from an encoder in which the wave period, duty cycle, phase difference and phase direction vary according to the operating speed, resolution and movement direction and are difficult to determine, which makes it difficult to detect deterioration, and to eliminate the wasted time and expense for the maintenance involved in taking the necessary measures. A system and a method for monitoring output signals of an encoder, in which an output signal output from an encoder body 1 corresponding to a basic operation pattern of an object 20 being measured which is set in an initial state is associated with the basic operation pattern and stored in a storage device 30; the object 20 being measured is then operated in accordance with the basic operation pattern at fixed intervals; an output signal output from the encoder body 1 at that time and output signal data in the initial state stored in the storage device 30 are compared, and a warning is output if the difference between the two signals is greater than a fixed magnitude.