36 results about "Sinusoidal modulation" patented technology

The invention relates to the technical field of gas detection, and provides a doped gas concentration detection method and system based on a gas analyzer. The method comprises the following steps: constructing a standard spectrum database under the same pressure and temperature as a to-be-measured site; the method comprises the following steps: introducing sample gas into an optical absorption cell, carrying out wavelength scanning through a tunable diode laser in a plurality of adjacent absorption spectral line intervals containing target gas and interference gas, superposing a high-frequency sinusoidal modulation signal on a driving current, and synchronously detecting a second harmonic component of transmission laser to generate an actual measurement spectrum; fitting the actually measured spectrum with a synthetic spectrum generated on the basis of a standard spectrum database, and outputting a target gas concentration ratio as a detection result when a residual error meets a threshold value, so as to solve the technical problem that the detection precision is reduced due to spectrum overlapping caused by interference gas, and achieve the purpose that the detection precision is reduced by constructing the standard spectrum database and second harmonic spectrum fitting analysis. And the accuracy and the anti-interference capability of gas detection are improved.

The invention discloses a three-phase three-wire three-level hybrid modulation switching method and device and a medium, and the method comprises the following steps: obtaining a three-phase sinusoidal modulation wave, and superposing a primary common-mode voltage to obtain a continuous first modulation wave; if the continuous space vector control is executed, comparing the first modulated wave with a carrier wave to form a first duty ratio signal; if the intermittent space vector control is executed, superposing the first modulation wave and a secondary common mode voltage based on a unified coefficient to obtain an intermittent second modulation wave; and according to a specific mode of intermittent space vector modulation, assigning a value to the unified coefficient to obtain a corresponding target intermittent space vector modulation wave. The device and the medium are both used for implementing the method. The method has the beneficial effects that the degree of freedom of the algorithm can be maximized through a PWM unification and coefficient modulation strategy; compared with a traditional mode, the complexity of an algorithm can be effectively reduced, and the reliability of overall code execution can be improved.

The invention discloses a single-stage multi-port converter DC side current ripple suppression method and device and a storage medium, and the method comprises the steps: obtaining an initial three-phase sinusoidal modulation wave according to the AC side three-phase voltage and current of a converter; obtaining a battery current control value according to the DC side photovoltaic voltage and current; obtaining an asymmetric carrier wave according to the DC side photovoltaic voltage and the energy storage battery voltage; according to the initial three-phase sinusoidal modulation wave and the asymmetric carrier wave, a battery current actual value is obtained, iteration is carried out according to an error between the actual value and a control value, and a zero-sequence component when the error is smaller than an error tolerance is obtained; injecting the zero-sequence component into the initial three-phase sinusoidal modulation wave to obtain an improved modulation wave; and intersecting the improved modulation wave with the asymmetric carrier wave to obtain a PWM driving signal of the converter. According to the invention, direct-current side current ripple suppression and power distribution between optical storage are realized through a zero-sequence component injection method, and the method has the characteristics of remarkable ripple suppression effect, low implementation cost and the like.

This application relates to a Rayleigh scattering noise suppression method and system for a distributed acoustic wave detection system. The method includes: performing optical phase sinusoidal modulation on a high-coherence continuous laser output from a narrow-linewidth laser in an FBG-based distributed acoustic detection system according to a set modulation scheme using an optical phase modulator; the set modulation scheme is Csin(2πf m t), C is the phase modulation amplitude, f m The phase modulation frequency and satisfying f m τ = k, where τ is the time difference between two adjacent reflected light pulses being detected, t is time, and k is an integer. A highly coherent continuous laser beam with sinusoidal phase modulation is passed through an unbalanced interferometer to generate dual light pulses. These dual light pulses are then injected into an FBG array for distributed acoustic wave detection. This achieves low-noise distributed acoustic wave detection and effectively improves the detection performance of FBG-based distributed acoustic wave detection.

The invention relates to the technical field of energy storage inverters, and discloses a three-port energy storage inverter and a control circuit and a control method thereof, and the method comprises the steps: achieving the flexible adjustment of an output voltage and an impedance mode through the design of a main circuit module and a control circuit module. The main circuit module can switch seven working modes to meet the requirements of different working conditions. The control circuit module uses a high-precision sensor, an advanced algorithm and a pulse width modulation technology to accurately control the output voltage waveform. The Hall sensor collects voltage and current, compares the voltage and current with sinusoidal modulation signals to generate error signals, outputs modulation signals after processing, drives the switching tube, and accurately controls voltage waveforms. The inverter improves the electric energy quality and dynamic regulation capability of renewable energy power generation, inhibits harmonic waves, improves the system stability and reliability, simplifies the multi-input port adaptation problem, reduces the system expansion complexity and cost, and has significant technical advantages and application prospects.

The invention discloses a force balance voltage modulation method of a Z-axis accelerometer, and belongs to the technical field of MEMS electrostatic driving. The Z-axis accelerometer comprises a mover mass block and a fixed type multifunctional multiplexing polar plate, a variable-spacing differential capacitor structure is formed, and displacement detection, driving force control and rigidity adjustment are achieved at the same time by multiplexing the structure. A PWM driving signal is generated through a dual PWM modulation method, sinusoidal modulation is carried out on the PWM driving signal and bias voltage together, a variable-spacing differential capacitor structure is used as a demodulator, a second-order mechanical vibration system is used as a low-pass filter, and a low-noise closed-loop driving torque is generated to stabilize the position of a mass block at a preset position. And meanwhile, low-noise direct-current static negative stiffness is generated, so that the system stiffness is reduced to a preset value. According to the invention, the variable-pitch differential capacitor structure can maintain the constant elastic coefficient of the system while generating the electrostatic driving torque, can provide sufficient control precision while reducing the leakage of driving signals, and can effectively suppress low-frequency noise.

The application discloses a laser radar correction method and device based on an angular frequency field, a storage medium and electronic equipment, and the method comprises the following steps: controlling a laser radar to emit sinusoidal modulation light to irradiate a whiteboard, acquiring four-phase original intensity data and displacement increment values; reconstructing a phase sequence for each pixel and estimating an angular frequency, and forming an angular frequency distribution of a full field of view; establishing an analytical coupling model of the angular frequency and a rotation matrix according to the distribution, an internal parameter matrix and a whiteboard normal vector, solving a rotation matrix estimation value by using a least square method, and combining an initial normal distance to calculate a translation vector estimation value; calculating real distances of each pixel to a whiteboard point according to the rotation and translation estimation values, recalibrating phase zero point offset and fixed mode phase noise, and generating a correction lookup table; and outputting the rotation, translation parameters and the lookup table. According to the application, a pattern target is not needed, and only a whiteboard and a guide rail are used to restore external parameters, system errors introduced by tilting are reduced, and the ranging and point cloud reconstruction precision are improved.

The invention discloses a laser frequency stabilization electric control system based on a modulation transfer spectrum, and the system is constructed based on a ZYNQ7030 heterogeneous SoC platform, and integrates laser modulation, signal collection, error extraction, feedback control and man-machine interaction functions. Comprising a sinusoidal modulation chain driven by a high-speed DAC and an electro-optical modulator which are used for realizing laser frequency modulation; the MTS signal acquisition link consists of a photoelectric detector, a low-noise amplifier and a high-speed analog-to-digital converter; feedback control is carried out on the frequency of the laser through the precise digital-to-analog converter and the current source circuit. Meanwhile, the system integrates an air cavity temperature control module, a multi-channel communication interface and a man-machine interaction module, and frequency stabilization and system management are achieved. According to the invention, high-precision and high-stability laser frequency locking based on the rubidium atom absorption spectrum can be realized without depending on an external frequency standard, and reliable frequency reference is provided for applications such as high-precision atom physical experiments, quantum sensing, spectral measurement and the like.

The invention discloses a speaker recognition model frequency modulation trigger injection method, particularly relates to the technical field of voice signal processing and artificial intelligence safety, and is used for solving the problems that an existing speaker recognition model back door injection method is insufficient in concealment, poor in black box environment adaptability, prone to distortion of trigger characteristics in the physical transmission process and poor in safety. And mainstream defense strategies such as model fine tuning, pruning and spectrum detection are difficult to resist. The method comprises the following steps: constructing a piecewise linear periodic low-frequency modulation curve for original voice, generating a smooth phase track according to a frequency and phase relationship, constructing a sinusoidal modulator to generate a hidden sample, mixing normal samples in proportion and uniformly marking, training a model by a black box, testing reproduction modulation and inputting the model; according to the method, the defects of insufficient concealment, black box adaptability, physical robustness and defensive resistance of an existing method are overcome, high-concealment, high-robustness and wide-application backdoor injection is realized, and reliable support is provided for security evaluation of a speaker recognition system.

The application belongs to the field of direct current transmission and relates to a sine modulation compensation method and system for a hybrid direct current energy consumption device, which comprises the following steps: obtaining an energy consumption valve sine modulation voltage according to surplus power of the hybrid direct current energy consumption device; if the energy consumption valve sine modulation voltage is negative, analyzing the cause of power imbalance of the energy consumption valve based on voltage non-negativity of a half-bridge energy consumption unit; and according to the cause of power imbalance of the device, expanding a compensation factor y through an alternating current component and reducing a compensation factor x through a direct current component, so as to ensure that the discharge energy and the charging energy of the energy consumption valve in a unit period are equivalent, and the average power of the energy consumption resistor in a unit period is equivalent to the surplus power. The method can effectively reduce the number of power devices of the hybrid direct current energy consumption device, greatly reduce the volume and cost of the hybrid direct current energy consumption device, and has great practical value and broad application prospect in the field of offshore wind power transmission through flexible direct current.

The invention discloses a mixing pulse width modulation method based on an elliptic vector model and an inverter system, and mainly relates to the technical field of mixing pulse width modulation inverters. Comprising the steps that a switching frequency generation model based on an elliptic vector model is established, and the switching frequency generation model is used for adjusting the switching frequency in real time according to the phase of sinusoidal modulation waves and completing frequency mixing modulation with controllable switching harmonic distribution frequency bands; performing discretization processing on the elliptic vector model by setting a harmonic discretization ratio and a carrier wave ratio to generate a sampling point phase sequence and a sampling period sequence in a sine period; according to the sampling period sequence, a pulse width modulation pulse sequence is generated through a natural sampling method and used for controlling on-off of an inverter switching device. The method has the beneficial effects that the problem of concentrated distribution of harmonic waves of the high-frequency switch is solved, the output efficiency of the converter is improved, and the purpose of enabling the output of the inverter to be more accurate, higher in quality and more efficient is achieved.

The invention discloses a gas detection method based on quantum cascade laser, and relates to the technical field of gas sensing. The method comprises the following steps: outputting laser triggered by a composite driving current by using a laser generator; the composite driving current is formed by superposing a high-frequency sinusoidal modulation waveform on a low-frequency scanning waveform; a quantum cascade laser is used for emitting laser, the laser passes through a multi-reflection pool after being collimated, gas to be detected is scanned, and a detector and a data acquisition card are used for synchronously acquiring light intensity scanning signals; in the processor, a time-division multiplexing algorithm and a compensation matrix are used for decoupling the light intensity scanning signal, corresponding gas and gas concentration are inverted and displayed in real time on a human-computer interaction interface, and when any gas concentration exceeds a corresponding preset threshold value, sound-light alarm is triggered, and an alarm signal is output to an administrator port. According to the invention, on the premise of not increasing the complexity of the system, the gas of which the absorption spectral line is very close to or even has cross interference can be accurately detected.

The application relates to a multi-stage motor initial position estimation method based on excitation signal sine modulation. An excitation voltage is taken as a carrier signal, and after being subjected to low-frequency sine modulation, the excitation voltage is applied to the stator winding of an exciter, and a three-phase low-frequency component is induced on the stator winding of a main motor to obtain a corresponding d-axis current. The d-axis current variance will reach a maximum value at a corresponding actual d-axis angle to obtain a rotor initial position theta 0_est1 , and the polarity of theta 0_est1 is identified according to the size of the d-axis transformed current before and after power-off. The method does not involve other complex filtering, phase-locked loop and other treatments, and thus has low requirements on the processor performance. Meanwhile, secondary identification of the magnetic pole is not needed. Finally, since a low-frequency signal is taken as a modulation wave, and a low-frequency induced signal is finally used as a data source for rotor initial position estimation, the attenuation of the low-frequency induced signal by the damping winding, the exciter winding and the main motor excitation winding is small, and thus the method has a high signal-to-noise ratio.

This invention relates to a flux-modulated electric generator that utilizes a rotating Reluctance Modulation Cylinder (RMC) to dynamically modulate magnetic reluctance between a Magnetic Field Source (MFS) and a Power Extractor Assembly (PEA) by changing the reluctance of medium between PEA and MFS by sinusoidally. The RMC is constructed from chirped laminated ferromagnetic material on a non-magnetic conductive base and is driven by a small mechanical motor. As the RMC rotates, its varying thickness modulates the magnetic reluctance sinusoidally, creating a time-varying magnetic flux in the PEA. The PEA, composed of multiple electromagnets, captures this modulated flux and converts it into electrical energy through Faraday's Law of Induction. The MFS, which consists of permanent magnets or superconducting magnets, provides a stable and high-intensity magnetic field for flux modulation. The system is highly efficient due to the lightweight nature of the RMC, which significantly reduces mechanical power requirements compared to traditional generators with heavy rotating rotors. The generator also allows for individual load extraction through its series-connected electromagnets, making it adaptable to various power applications. This novel design offers enhanced efficiency, reduced mechanical wear, and versatility in power generation for both small and large-scale applications.

The invention relates to the technical field of power electronics, and discloses a multiplexing active clamping high-frequency link inverter secondary side modulation method, which comprises the following steps of comparing a reference sine modulation wave with a triangular carrier wave; the S1 and the S2 work in a complementary state with the frequency being the switching frequency fs and the duty ratio being (0.5-Td) / Ts. According to the secondary side modulation method for the multiplexing active clamping high-frequency chain inverter, the suppression effect on voltage ringing is not influenced while the soft switching characteristic is realized; the simulation waveform of the secondary side voltage of the transformer shows that the voltage ringing is suppressed near the steady-state voltage, so that the working stability and reliability of the inverter are ensured, and the damage of the high-voltage ringing to the device is avoided.

The invention discloses a laser self-mixing interference rotating speed measurement method based on current modulation, and the method comprises the following steps: S1, building a light path, irradiating the laser emitted by a fixed-wavelength solid-state laser to a fixed measurement point of a measured rotating workpiece, and feeding back the light reflected by the workpiece in a diffuse manner into a laser cavity to form self-mixing interference; s2, laser current modulation: inputting a high-frequency sinusoidal modulation current with direct-current bias to the fixed-wavelength solid-state laser, and superposing a high-frequency modulation component in a self-mixing interference signal; s3, interference signal acquisition: a self-mixing interference signal containing a high-frequency modulation component is acquired and converted into a digital electric signal; and S4, signal demodulation and rotation speed calculation: processing the digital electric signal to extract stripe subdivision information, and calculating the instantaneous rotation speed of the workpiece. Compared with the prior art, the laser self-mixing interference rotating speed measuring device based on current modulation and the measuring method thereof have the advantages that high resolution and high signal-to-noise ratio are achieved.

The invention relates to the field of intelligent manufacturing, and discloses a binary sulfur hexafluoride decomposition gas detection method and device based on an infrared spectrum. The binary sulfur hexafluoride decomposed gas detection method based on the infrared spectrum comprises the following steps: modulating a direct current bias current based on a low-frequency linear scanning current and a high-frequency sinusoidal modulation current to obtain a direct current driving current, and inputting the direct current driving current into a laser generator to generate detection laser; receiving transmission laser after the detection laser passes through the decomposition gas to be detected; obtaining a transmissivity-time function of the decomposition gas to be detected according to the transmission laser and the detection laser; and determining a first detection result of the first target gas and a second detection result of the second target gas in the decomposition gas to be detected according to the transmissivity-time function. The binary sulfur hexafluoride decomposition gas detection method and device based on the infrared spectrum provided by the invention have the technical effect of realizing high precision of CO and CO2 gas in carbon-containing SF6 mixed gas.

This invention discloses a method for identifying broadband voltage fluctuation types in power grids based on multi-feature fusion, relating to the field of voltage fluctuation technology. It addresses the problem of fluctuation type confusion under conditions of multiple disturbances and non-stationary operation. The method involves acquiring three-phase voltage data from voltage transformers and calculating the voltage deviation rate, while simultaneously retrieving the short-time flicker index. A fluctuation identification mechanism is jointly triggered based on these two factors. After triggering, a broadband voltage signal is acquired and modal decomposition is performed. The instantaneous frequencies of each mode are extracted and classified. Historical voltage data is retrieved to construct the voltage envelope trajectory, and the envelope asymmetry is calculated. Disturbances are introduced to different modes to enhance energy, and the modal energy spectra are calculated and fused to form modal modulation feature vectors. A pre-trained support vector machine model is used for classification mapping, achieving accurate identification of sinusoidal modulation, rectangular modulation, and interharmonic modulation voltage fluctuations, thus improving identification accuracy under complex operating conditions.

The invention discloses an energy-saving control method and device for a three-phase four-leg inverter and a storage medium, and belongs to the technical field of power electronics. The energy-saving control method comprises the following steps: acquiring a sinusoidal modulation input voltage signal of any phase and an output current signal of any phase of the three-phase four-leg inverter; determining a zero crossing point phase difference between the sinusoidal modulation input voltage signal and the output current signal; determining a common-mode voltage value according to the zero crossing point phase difference; according to the common-mode voltage value, correcting a sinusoidal modulation input voltage value of the sinusoidal modulation input voltage signal to obtain a sinusoidal modulation input voltage correction value; and determining a modulation input voltage signal of each phase of the three-phase four-leg inverter according to the sinusoidal modulation input voltage correction value. The energy-saving control method is used for reducing the circuit design cost.

The application discloses a photovoltaic grid-connected inverter system and a control method based on discontinuous modulation, and relates to the technical field of multilevel inverter control. The method comprises the following steps: obtaining a three-phase sinusoidal modulation wave of a multilevel inverter, constructing a square wave signal and adjusting the amplitude of the square wave signal, and dividing a clamping interval according to the intersection of the square wave and the three-phase sinusoidal modulation wave; based on midpoint balance and resonance suppression, the square wave signal is subjected to compensation voltage superposition; a control threshold for presetting the control midpoint voltage fluctuation range is determined, and the priority of controlling the midpoint voltage and suppressing common-mode resonance is determined; the square wave compensation voltage is adjusted according to the priority; the three-phase sinusoidal modulation wave and the square wave after the compensation voltage adjustment are compared, a DPWM common-mode modulation wave is determined, and a DPWM modulation wave is obtained, and the switching tube is controlled according to the DPWM modulation wave. The application can realize the multi-objective optimization control of midpoint voltage balance, common-mode resonance suppression and reduced switching loss.

The application discloses a single-stage multi-port converter DC side current ripple suppression method and device and a storage medium. The method comprises the following steps: obtaining an initial three-phase sinusoidal modulation wave according to three-phase voltage and current on the AC side of the converter; obtaining a battery current control value according to a DC side photovoltaic voltage and current; obtaining an asymmetric carrier according to the DC side photovoltaic voltage and an energy storage battery voltage; obtaining an actual battery current value according to the initial three-phase sinusoidal modulation wave and the asymmetric carrier, and performing iteration according to the error between the actual value and the control value to obtain a zero sequence component when the error is less than an error tolerance; injecting the zero sequence component into the initial three-phase sinusoidal modulation wave to obtain an improved modulation wave; and intersecting the improved modulation wave with the asymmetric carrier to obtain a converter PWM driving signal. The application realizes DC side current ripple suppression and power distribution between the photovoltaic and the energy storage battery through a zero sequence component injection method, and has the characteristics of remarkable ripple suppression effect and low implementation cost.

The application discloses a flicker measurement method based on feature reduction, and steps of the method comprise the following steps: extracting a power grid flicker envelope D(n) by using an improved Teager energy operator with two-point interval; analyzing and processing the obtained envelope D(n) by using a five-term Rife-Vincent window interpolation FFT method to obtain flicker modulation wave feature parameters: amplitude coefficient m i , frequency f i and initial phase angle θ i ; reducing the obtained feature parameters into a sinusoidal modulation signal, removing the amplitude coefficient m i from 4 / π and combining other parameters to reduce the sinusoidal modulation signal into a rectangular modulation signal; taking (1±10%) of the envelope signal D(n) as a threshold, comparing the number of data points of the reduced signal within the threshold, when the number of data points of one group is greater than N / 4, the greater one is the flicker modulation wave signal, and corresponding flicker parameters are output; if the number of data points of both groups is less than N / 4, no flicker occurs. The application provides a discrimination basis for flicker identification, overcomes the problem that a traditional flicker detection algorithm cannot effectively identify a flicker signal and is limited in use, and improves the detection precision of the flicker.

This invention discloses a zero-sequence component injection DPWM modulation method for driving a dual Y-shift 30° six-phase permanent magnet synchronous motor. The method involves superimposing a sinusoidal modulation wave with a zero-sequence component to form a 60° clamping discontinuous modulation wave. The steps include: S1: Obtaining the six-phase voltage modulation wave and its output current; S2: Taking three-phase windings with a 120° phase difference as one group and three-phase windings with a 30° electrical phase difference from the previous group as another group, obtaining the minimum absolute value of the voltage modulation wave and the maximum absolute value of the corresponding output current in each group; S3: Calculating the injected zero-sequence component in each group; S4: Superimposing the zero-sequence component onto the corresponding voltage modulation wave to obtain a DPWM modulation wave that adaptively clamps the maximum conduction current. This invention determines the optimal clamping region by detecting the inverter output current and reference voltage, reducing system switching losses. The zero-sequence component injection method avoids complex vector calculations, demonstrating significant application value.

The application discloses a lightning stroke imaging method based on piezoelectric array waveguide response, comprising the following steps: S1, arranging a sparse piezoelectric-waveguide array in a measured structure; S2, acquiring a lightning stroke waveguide response signal of the sparse piezoelectric-waveguide array; S3, filtering and processing the lightning stroke waveguide response signal through convolution of a sinusoidal modulation signal; and S4, pre-processing the lightning stroke waveguide response signal and implementing lightning stroke comprehensive imaging based on signal delay superposition. The lightning stroke imaging method based on piezoelectric array waveguide response is adopted, the lightning stroke waveguide response signal of the piezoelectric array is subjected to delay superposition for comprehensive imaging, online positioning monitoring of lightning stroke points is realized, and therefore high-precision imaging of lightning stroke events of large-area aviation composite material structures can be realized.

This invention discloses a single-stage self-equalizing IIOS converter for distributed photovoltaic MVDC aggregation. The invention comprises N sub-modules, each a three-port structure integrating interleaved parallel Boost units and hybrid full-bridge LLC resonant units. The former implements MPPT (Multi-Level Testing) for the distributed photovoltaic array, while the latter provides isolated voltage boost. Each sub-module's first port connects to an independent photovoltaic array, its second port is connected in parallel to a low-voltage DC bus, and its third port is connected in series to a medium-voltage DC bus. A control method is also provided based on this converter. By employing sinusoidal modulation with consistent primary and secondary drive logic, the hybrid full-bridge LLC resonant unit operates in DC transformer mode, with a constant sinusoidal resonant current. Furthermore, the second ports of each sub-module are directly connected in parallel, thus enabling self-equalizing output voltage among the sub-modules. This invention only requires sampling the output voltage and current of each distributed photovoltaic array to achieve MPPT for each sub-module and self-equalizing output voltage among sub-modules, eliminating the need for sampling the voltage at the third port or additional voltage equalization circuitry.

Disclosed in the present application are a dual-frequency control method for a power factor during grid connection of a flyback inverter, and a controller. The method comprises: acquiring an operating electrical signal of a power grid; obtaining a first sinusoidal modulation wave signal; obtaining a second sinusoidal modulation wave signal; on the basis of a power factor, determining a phase angle difference and a time difference corresponding to the phase angle difference; obtaining a sinusoidal correction modulation frequency; generating a sinusoidal correction modulation wave signal, the frequency of which is the sinusoidal correction modulation frequency; and by means of the sinusoidal correction modulation wave signal, controlling a flyback inverter to output an alternating current. The power factor is adjusted by means of adjusting the phase difference between a target power grid and a sinusoidal correction modulation wave; moreover, a first sinusoidal modulation wave can operate independently when a power source only has active power, and the sinusoidal correction modulation wave can operate independently when the power source requires reactive power adjustment. The flyback inverter is controlled by means of the sinusoidal correction modulation wave in the present application, such that the flyback inverter can accurately adjust the power factor during grid connection, and a harmonic distortion rate is reduced.

The invention discloses a power converter, a control method thereof and an energy storage system, and relates to the technical field of power electronics, and the control method comprises the steps that when an NPC type three-phase multi-level inverter circuit converts alternating current of a power grid into direct current to charge an energy storage battery, or the energy storage battery is charged by the NPC type three-phase multi-level inverter circuit; when the NPC type three-phase multi-level inverter circuit converts alternating current of a power grid into direct current to charge an energy storage battery and the power of the NPC type three-phase multi-level inverter circuit is larger than or equal to a preset power threshold value, a first discontinuous pulse width modulation signal is output to each phase of bridge arm; the amplitude of the bridge arm phase voltage of any bridge arm is clamped at half of the positive direct current bus voltage or half of the negative direct current bus voltage in a first interval, and the first interval is the interval of the initial sinusoidal modulation signal of the bridge arm at the two symmetrical sides of the peak value. Therefore, the risk that electronic components in the power converter are damaged due to overhigh junction temperature can be reduced, the overload capacity of the power converter is improved, and the stability and reliability of a power system are ensured.

The invention discloses an SPWM (sinusoidal pulse width modulation) method for a load test of three-level equipment powered by a single direct-current power supply, and belongs to the technical field of power electronics. The method is based on an SPWM modulation system, initial sinusoidal modulation waves are generated by inputting modulation parameters, two paths of modulation waveforms are generated after upper and lower bus voltages are collected, the two paths of modulation waveforms are compared with triangular carrier waves to obtain switching signals, the switching signals are synthesized into three-level switching signals, and then operation of a power device is controlled. The method is characterized in that positive and negative half shafts are respectively modulated and then integrated, the problems of bus voltage dynamic unbalance and load current fluctuation under single power supply are solved, extra closed-loop control is not needed, the system complexity and cost are reduced, the sine degree of output voltage and the stability of load current are ensured, and the reliability of the system is improved. The method is suitable for three-level equipment with various topological structures, such as a wind power converter and an energy storage PCS.

The application discloses a common-mode resonance suppression method and system of a three-level inverter under a high-efficiency modulation mode, and comprises the following steps: obtaining low-frequency and medium-frequency component information of three-phase bridge arm output currents of the three-level inverter, and obtaining corresponding d-axis components, q-axis components and common-mode components through coordinate transformation; when performing differential-mode control, the d-axis components and the q-axis components enter a differential-mode current controller for differential-mode current control, and the output of the differential-mode current controller is subjected to coordinate transformation to obtain three-phase sinusoidal modulation waves; based on the three-phase sinusoidal modulation waves, a clamping phase and a non-clamping phase in the three phases are determined; when performing common-mode suppression, the common-mode components are sent into a common-mode resonance suppression link to obtain a common-mode control quantity; the common-mode control quantity is injected into the non-clamping phase to obtain a final three-phase modulation wave, and then a driving signal of a switching device is obtained, so that the three-level inverter is controlled. The application can eliminate the influence of switching frequency components and multiple frequency components, and improve sampling precision.

The invention relates to the technical field of voltage transformation, in particular to a high-frequency isolation type single-phase energy storage DC-AC conversion system, which generates different driving signals by comparing a power-frequency sinusoidal modulation wave with a high-frequency triangular carrier wave, controls a primary side full-bridge circuit and a secondary side chopper circuit to carry out voltage transformation, and improves the conversion efficiency. Therefore, the working frequency of the isolation transformer can be improved from power frequency to high frequency, the high-frequency transformer can be used for replacing a traditional power frequency transformer, output current and voltage closer to sine waves can be generated, magnetic loss and copper loss can be optimized, the size and weight of the high-frequency transformer are smaller, and cost is lower. The power density of DC-AC conversion is improved, and a multi-mode driving signal is generated through comparison of a power frequency sinusoidal modulation wave and a plurality of high-frequency triangular carriers, so that a target level generates more-mode changes, sine waves can be simulated more accurately, the waveform quality of output AC is improved, and waveform distortion of the output AC is avoided.