186 results about "Total harmonic distortion" patented technology

The invention discloses a self-adaptive harmonic current suppression method for harmonic waves of a photovoltaic inverter, which belongs to the technical field of power quality control of a power system and comprises the following steps of: compensating a control strategy through a self-adaptive harmonic component of the photovoltaic inverter by adopting a'detection-reverse injection 'framework; the difference between the residual apparent capacity of the inverter after fundamental wave power supply and the borne harmonic power is used as an adaptive quantity, and the total harmonic distortion rate of the grid-connected point is reduced to the maximum extent on the premise of no overload; the method comprises the following steps: firstly, constructing a real-time harmonic detector based on a cascade generalized integrator; secondly, an inverter impedance model is established from the aspect of impedance stability, and a control parameter stability boundary is determined; then, a self-adaptive harmonic control strategy is introduced into the single-inverter grid-connected system, and a reasonable parameter setting method is provided on the basis of considering stability limitation; afterwards, a capacity-matched harmonic power distribution algorithm is provided for a multi-inverter parallel system, and the efficiency and operation stability of a photovoltaic grid-connected power generation system are improved.

The invention discloses an electric energy meter abnormal phenomenon automatic detection and identification method and system, and relates to electric digital data processing, and the method comprises the steps: carrying out the digital signal processing of initial data, the voltage effective value, the total harmonic distortion rate and the analysis of communication message abnormal codes, and generating a structured feature matrix; on the basis of the structured feature matrix, threshold comparison, composite condition judgment and continuous anomaly detection are executed through multi-level rule triggering, and an anomaly event report is generated; comparing the abnormal event report with a historical case, obtaining the similarity between the current abnormal event report and the historical case, and obtaining a similarity TOP-N case set; generating an anomaly diagnosis report by using weighted evidence fusion in combination with rule triggering intensity quantification and case matching credibility conversion; and updating the case library according to the abnormality diagnosis report, and counting and adjusting a rule threshold based on a sliding window. According to the method, the abnormal judgment threshold values of key parameters such as voltage and harmonic waves can be adjusted in real time through dynamic threshold value optimization, and the adaptability is improved.

The invention relates to the technical field of electric power system control, and discloses an electric power system arc harmonic collaborative suppression and intelligent closed-loop control system, which comprises the steps of: acquiring sensor data and uploading the sensor data to an edge computing unit by deploying a sensor; wavelet threshold denoising and electromagnetic interference compensation are adopted; the method comprises the following steps: constructing a coupling model containing arc plasma dynamic resistance, optimizing VMD parameters through PSO, extracting a joint feature vector, filling an arc and harmonic dynamic coupling analysis gap, calculating a total harmonic distortion rate and arc extinction time in combination with a power grid damping ratio, solving an optimal SVG trigger angle, and solving the problem of lack of power grid stability evaluation; correcting the opening time of the circuit breaker, calculating the error of the total harmonic distortion rate and the error of the arc extinction time, and adjusting the SVG trigger angle; calculating the precision of the evaluation model, calculating the full life cycle through the aging coefficient, analyzing and judging whether an early warning signal is generated or not, and triggering equipment replacement early warning based on the generated early warning signal.

The invention provides a single-phase four-quadrant rectifier IGBT open-circuit fault diagnosis method under multiple working conditions, and relates to the technical field of IGBT fault diagnosis. Historical data of alternating current side voltage, alternating current side current and direct current side voltage of the single-phase four-quadrant rectifier are obtained, and a total harmonic distortion rate threshold value, a direct current side voltage threshold value and an alternating current side current first threshold value are obtained. And constructing and training an IGBT open-circuit fault positioning identification model. Detecting the total harmonic distortion rate of the alternating-current side current of the single-phase four-quadrant rectifier in real time, if the total harmonic distortion rate exceeds a threshold value, entering fault positioning, collecting and calculating the average value of the direct-current side voltage and the alternating-current side current in the period, and judging the fault of the single-phase four-quadrant rectifier under the specific working condition according to the comparison of the average value and the threshold value. Or using an IGBT open-circuit fault positioning identification model to diagnose the fault; if the threshold value is not exceeded, the next period is continuously monitored. According to the invention, the IGBT fault diagnosis efficiency and accuracy of the single-phase four-quadrant rectifier are improved.

The embodiment of the invention discloses a collaborative optimization method and device for the power quality of a high-permeability transformer area. The method comprises the following steps: acquiring three-phase voltage, three-phase current and environment temperature data; the voltage deviation, the three-phase unbalance degree, the total harmonic distortion rate and the reactive vacancy of the high-permeability transformer area are calculated based on the three-phase voltage and the three-phase current; taking voltage deviation as a primary optimization target, considering optimization of three-phase unbalance degree, total harmonic distortion rate and reactive vacancy, constructing a multi-target optimization function, and carrying out dynamic constraint on an optimization process based on environment temperature data; solving the multi-objective optimization function by adopting an optimization algorithm to obtain a group of optimal decision variables, and converting the decision variables into corresponding control instruction sets; and the control instruction set is issued to the on-load voltage regulating transformer, the reactive compensation equipment and the power electronic compensation module for execution. Therefore, the problems of voltage out-of-limit, harmonic pollution and imbalance are effectively solved through a multi-target cooperation and temperature self-adaption mechanism.

The invention discloses a real-time noise reduction method and system supporting Bluetooth audio interaction, and the method comprises the steps: collecting an environment audio signal and a Bluetooth interaction audio signal, and carrying out the timestamp alignment and spatial calibration of the environment audio signal and the Bluetooth interaction audio signal; an improved multivariate variational mode decomposition algorithm is adopted to decompose and extract noise features, the noise features are combined with user historical noise data, a dynamic noise model is constructed through a long-short-term memory network, parameters are updated in real time, Bluetooth interaction audio content features and a user behavior data recognition scene are analyzed, and a noise reduction strategy is determined. And according to the dynamic noise model and the scene result, reinforcing learning to optimize filter parameters, generating a directional anti-noise signal to carry out noise reduction on the Bluetooth interaction audio signal, collecting the noise reduction intensity manually adjusted by a user, calculating voice definition and total harmonic distortion, and carrying out noise reduction on the Bluetooth interaction audio signal. And inputting a feedback and evaluation result into the modeling and noise reduction steps, carrying out dynamic range adjustment, sound channel balance and power amplification on the audio after noise reduction, and outputting the audio through a loudspeaker.

The invention relates to the technical field of supervision control, in particular to a new energy storage optimization control method and system, and the method comprises the following steps: collecting a grid-connected point voltage amplitude deviation, a frequency deviation and a voltage total harmonic distortion rate, and generating a power grid stress index; according to the method, the multi-dimensional state vector is constructed by collecting the grid-connected point voltage amplitude deviation, the frequency deviation and the total harmonic distortion rate to generate the stress index reflecting the power grid operation pressure, accurate quantitative sensing of the power grid state is achieved, the power grid supporting gain coefficient is dynamically generated according to comparison of the index and the preset threshold value, and the power grid supporting effect is improved. And the total required power to be responded by the energy storage system is adjusted and determined, so that the power support strength is matched with the actual demand of the power grid, and insufficient response or excessive response is avoided.

The invention relates to the cross technical field of computer-aided engineering and audio equipment design, discloses a circuit design simulation-based disc player design optimization method and system, and aims to solve the problem that the existing disc player design depends on physical prototype trial-manufacture and subjective listening evaluation and lacks multi-physical domain co-simulation capability. The method comprises the following steps: constructing a unified multi-physical domain model comprising a mechanical transducer, an electromechanical transducer and an electronic circuit sub-model; bidirectional coupling co-simulation based on the time sequence is executed, and an output electric signal is generated; extracting objective audio performance indexes such as total harmonic distortion and signal-to-noise ratio; and carrying out multi-objective optimization on the key design parameters by utilizing a genetic algorithm, and outputting a Pareto optimal scheme. The system comprises a model construction module, a co-simulation module, a performance index extraction module and an optimization module. Through high-fidelity full-link simulation and automatic optimization, the design efficiency and the audio fidelity are remarkably improved, and the research and development cost is reduced.

The invention discloses a permanent magnet synchronous motor model prediction control method based on multi-target Pareto optimum, which comprises the following steps: measuring two-phase current, motor rotating speed and rotor position of a permanent magnet synchronous motor, converting the two-phase current into d-axis current and q-axis current according to the rotor position, and converting an alternative voltage vector of an inverter into d-axis voltage and q-axis voltage at the same time; inputting the d-axis current, the q-axis current, the d-axis voltage, the q-axis voltage and the rotating speed of the motor into a current prediction model of the permanent magnet synchronous motor, and predicting a future current state value; establishing a multi-target optimization model including torque ripple, current total harmonic distortion, switching frequency and power loss, calculating by using a multi-target particle swarm algorithm in combination with non-dominated sorting and congestion distance to obtain a Pareto optimal solution set, obtaining an optimal weight factor, and automatically adjusting target weights according to motor operation states under different operation conditions; and constructing a cost function based on the optimal weight factor, and selecting a voltage vector enabling the cost function to be minimum as optimal control output.

The application discloses a single-stage three-phase high-frequency isolation type conversion circuit and a closed-loop control method. The single-stage three-phase high-frequency isolation type conversion circuit generates a modulation ratio and a vector angle on the basis of synchronous control of a fundamental wave and a harmonic wave of a three-phase current based on three-phase voltage of a three-phase three-wire power grid and the three-phase current of the three-phase three-wire power grid, generates a primary side driving signal and a secondary side driving signal according to the modulation ratio and the vector angle, the primary side driving signal is used for driving a three-phase matrix converter, and the secondary side driving signal is used for driving a full-bridge inverter. The fundamental wave and the low-frequency harmonic wave of the power grid current can be synchronously controlled, low-order harmonics can be eliminated, the sinusoidal degree of the grid-connected current can be improved, and thus the quality of the power grid current and total harmonic distortion can be improved.

The invention provides an alternating-current side third harmonic weakening modulation method of a railway power regulator under the condition that direct-current bus voltage contains frequency doubling ripples. The method comprises the following steps: constructing a bus voltage state space model of the railway power regulator, and designing a non-delay adaptive state observer to extract direct current component information of bus voltage; separating information of a direct current component and a double frequency ripple component of the bus voltage through a self-adaptive state observer; introducing the direct-current component information into voltage and current double-closed-loop control; designing a secondary pulse modulation ratio opposite to a ripple voltage phase through the extracted ripple pulse parameters; the third harmonic on the alternating current side of the RPC is weakened by injecting an opposite pulsation modulation ratio into a modulation coefficient; according to the method, under the condition that circuit topology and control strategy complexity are not increased, output voltage third harmonics are effectively weakened, direct current side voltage double frequency fluctuation is reduced, meanwhile, power coupling between the alternating current side and the direct current side can be compensated, the requirement for the capacitance value of a bus capacitor is reduced, the total harmonic distortion rate is reduced, and the service life of the bus is prolonged. And long-term stable operation of the system is guaranteed.

A harmonic modeling method of a power amplifier solves the problem that a traditional modeling method is not suitable for harmonic modeling analysis of a high-switching-frequency topological structure, and comprises the following steps: obtaining baseband harmonic and sideband harmonic caused by modulation nonlinearity according to the number of parallel half bridges, a modulation wave function and a carrier function in the power amplifier; according to the topological structure of the power amplifier, obtaining a circuit equation of the topological structure in the dead-zone time period; calculating the current amplitude envelope of the resonant inductor; and calculating a voltage error caused by the dead-zone time period according to the calculated current amplitude envelope in combination with a circuit equation of the dead-zone time period, performing Fourier decomposition on the voltage error to obtain distortion harmonics caused by the dead-zone time period of the power amplifier, and obtaining total harmonics in combination with the obtained baseband harmonics and sideband harmonics. According to the invention, the switching frequency when the total harmonic distortion is the lowest can be obtained through modeling.

The invention is suitable for the technical field of sensors, and provides a wireless current sensor, a current detection method and a computer program product, an electric field electricity taking module and a magnetic field electricity taking module take electricity from an alternating electric field and an alternating magnetic field around a to-be-detected power transmission line respectively, and provide a first direct current and a second direct current for an energy storage module respectively; a first voltage sampling value and a second voltage sampling value are respectively output; the processing module determines the electric field power and the magnetic field power of the power transmission line to be measured at the current moment according to the first voltage sampling value, the second voltage sampling value, the environment temperature value and the environment humidity value at the current moment; the current system working condition is determined according to the electric field power, the magnetic field power, the total harmonic distortion rate, the waveform flattop rate and the crest factor of the current detection signal in the current power frequency period, and the current detection module is controlled to carry out current detection based on a current detection strategy matched with the current system working condition. And high stability and current detection precision can be realized under all working conditions.

The invention discloses a permanent magnet synchronous motor wide speed range model prediction control method and system based on a mean value reduction optimization algorithm, and belongs to the technical field of motor control. According to the method, a discrete mathematical model of the permanent magnet synchronous motor is established under a d-q rotating coordinate system, a q-axis current reference value is generated by an outer ring through a speed PI regulator, and a d-axis current reference value is calculated in combination with a maximum torque per ampere (MTPA) principle and a weak magnetic region voltage constraint; finite control set model prediction control is adopted in an inner ring, enumeration prediction is conducted on candidate voltage vectors of the three-phase voltage source type inverter, a cost function containing a d-axis current error, a q-axis current error and an electromagnetic torque error is constructed, an optimal voltage vector is selected, and a three-phase PWM signal is generated through space vector pulse width modulation to drive a motor. The system is provided with a mean value reduction optimization module, joint optimization is carried out on speed outer ring PI parameters and cost function weight coefficients in the off-line stage, the parameters are stored in a lookup table, and automatic setting of control parameters is achieved. The permanent magnet synchronous motor can improve the dynamic response performance of the rotating speed and the current in the base speed area and the weak magnetic area, reduce the total harmonic distortion of the stator current, improve the voltage utilization rate and the overall operation efficiency of the permanent magnet synchronous motor, and is suitable for occasions such as electric vehicle driving and high-performance servo systems.

The embodiment of the invention provides a multi-channel transcranial focused ultrasound regulation and control system and method based on high-frequency precise-control SPWM (Sinusoidal Pulse Width Modulation). The system is applied to the technical field of ultrasonic treatment and comprises a main control module, an ultrasonic driving module, a frequency tracking module, a power supply module and an ultrasonic transducer, the master control module is used for SPWM signal generation, driving strategy switching and frequency tracking algorithm deployment. The ultrasonic driving module is used for receiving the SPWM signal output by the main control module, amplifying and filtering the SPWM signal and then outputting a target sine driving signal to the ultrasonic transducer; and the frequency tracking module is used for realizing real-time detection and tracking of the actual resonant frequency of the transducer. According to the invention, the hardware cost of multi-channel driving is reduced; the total harmonic distortion of the driving signal is reduced, and the frequency and phase control precision is improved; multi-channel driving is realized through a single MCU, and cortical and deep brain region regulation and control are compatible; the stability of the treatment process is guaranteed while the energy utilization efficiency is improved.

The invention belongs to the technical field of power system optimization operation, and particularly relates to an energy storage low-voltage active compensation method and system based on an improved multi-objective evolutionary algorithm. In combination with energy data collected from an energy management system in real time, a multi-objective optimization model is solved through a multi-objective evolutionary algorithm to obtain energy storage reference compensation power, then the energy storage reference compensation power is used as control input to construct a sliding mode controller, and the charging and discharging behaviors of the energy storage device are optimized through the sliding mode controller. And active power compensation of the power system in the transformer area is realized. The problems of heavy overload, three-phase imbalance and low voltage of end users of the transformer can be solved at the same time, stable power supply of a transformer area power system is ensured, and the power supply quality is improved.

The invention relates to a model training method and device and a signal conversion method. The model training method comprises the following steps: inputting an original digital signal sent by a digital signal source into an initial model to obtain a sample digital signal output by the initial model; performing digital-to-analog conversion on the sample digital signal through a digital-to-analog conversion circuit in the signal processing chip to obtain a sample analog signal corresponding to the sample digital signal; determining a predicted value of a nonlinear distortion index of the digital-to-analog conversion circuit according to the sample digital signal and the sample analog signal; wherein the nonlinear distortion index comprises a total harmonic distortion index and / or an intermodulation distortion index; and performing parameter adjustment on the initial model according to the predicted value and the expected value of the nonlinear distortion index to obtain a digital signal conversion model. The digital signal conversion model obtained through training of the method can process original digital signals so as to compensate nonlinear distortion of a digital-to-analog conversion circuit.

The invention provides a permanent magnet synchronous motor sensorless control method based on self-adaptive high-frequency signal injection, and the method comprises the steps: carrying out the online calculation of the amplitude of an optimal high-frequency injection signal through building a relation model of the amplitude of a pulsating square wave high-frequency voltage signal, the total harmonic distortion rate of motor current, and the fundamental current; generating a pulsating square wave high-frequency voltage signal with the optimal amplitude; a current envelope containing rotor position information is extracted from high-frequency response current through a high-pass filtering and synchronous demodulation technology, and rotor position and rotating speed information is extracted by adopting a phase-locked loop structure and fed back to a closed-loop control system. According to the method, the current harmonic content is strictly limited within the preset range by dynamically adjusting the amplitude of the injection signal, high-frequency noise caused by a traditional fixed amplitude injection method is reduced, quick response and robustness of a system during load sudden change are ensured, and the contradiction that noise and precision are irreconcilable in a traditional method is effectively solved.

The invention relates to an AC / DC power distribution network coupling node state linearization reconstruction control method and device. The method comprises the following steps: step 1, constructing a dynamic equation under a rotating coordinate system; step 2, linear decoupling of nonlinear AC / DC coupling nodes is realized, and a new energy state is selected based on a port Hamiltonian theory; 3, the unknown uncertainty of the system in the rotating coordinate system is represented in a lumped mode; 4, duty ratio related items in the polynomial obtained through derivation are selected as control input, and other items obtained through derivation are lumped into another unknown uncertainty disturbance lumped item; step 5, constructing a linearized standard state space model; step 6, determining a control reference state; and 7, designing a corresponding control law, and further completing feedback linearization-based AC / DC power distribution network coupling node state reconstruction control. The transient regulation time is shortened by more than 90%, the total harmonic distortion rate of the voltage is reduced by more than half, and the dynamic performance and the electric energy quality of the system are remarkably improved.

An audio input circuit capable of avoiding the deterioration of total harmonic distortion (THD) includes a single-ended signal input circuit, a differential signal input circuit, a first amplifier circuit and a second amplifier circuit. The single-ended signal input circuit is enabled by a switch in a single-ended mode to output a single-ended audio signal to the first amplifier circuit. The differential signal input circuit is enabled by a switch in a differential mode to output a differential audio signal to the first amplifier circuit. The first amplifier circuit outputs an inverted audio output signal to the second amplifier circuit according to the signal received thereby. The second amplifier circuit outputs a non-inverted audio output signal according to the signal received thereby. In the single-ended and differential modes, the signals input to the non-inverted input terminals of the first and second amplifier circuits are DC signals to stabilize the on-resistance linearity of the switches in the audio input circuit and to avoid the deterioration of THD of the audio input circuit.

The invention discloses a current harmonic self-interleaving elimination control method and device for a common DC bus parallel grid-connected inverter, and the device comprises two same grid-connected inverter cabinets which are connected in parallel, and each parallel branch of the two grid-connected inverter cabinets is provided with a sensing filtering unit, a hysteresis comparison unit, and a PWM modulation unit. The method comprises the following steps of: simultaneously inputting the same current simulation given quantity into parallel branches respectively connected with two same grid-connected inverter cabinets which are connected in parallel, independently carrying out hysteresis control on each parallel branch, and finally driving the two grid-connected power cabinets to output current through sensing, filtering, hysteresis comparison and PWM (Pulse-Width Modulation) links, switching harmonics of output currents of the two grid-connected power cabinets are naturally distributed in a staggered mode due to the self-stabilization effect. The method does not depend on any synchronous or communication mechanism, and the current on the parallel branches of the two grid-connected inverter cabinets is automatically staggered and connected in parallel, so that the total harmonic distortion of the total grid-connected current is reduced, and the reliability is ensured while the system design is simplified.

The invention discloses a nanosecond square wave transient impedance tower grounding defect on-line detection method and system. The method comprises the steps that distributed potential sensors are arranged on the periphery of a tower grounding body, and multi-channel synchronous acquisition is established; injecting a rectangular pulse signal into the grounding down lead, and superposing a damping sine component subjected to frequency response compensation; synchronously acquiring voltage and current responses, calculating a transient impedance differential ratio, a total harmonic distortion rate and a wavelet packet energy entropy, and judging a defect type according to a preset threshold value and a weighted fusion criterion; constructing and solving a ground potential field model, and positioning a defect position; the system is composed of a nanosecond square wave generator, a distributed potential sensor, a data acquisition and synchronization module, a signal analysis module and a ground potential tomography module, and sensor signals are subjected to differential transmission through a twisted-pair shielding cable to suppress interference. According to the invention, rapid and accurate identification and positioning of the grounding defect of the tower under the non-power-off condition are realized, the identification rate is high, and the positioning precision is excellent.

The invention discloses a switch control method, a switch control circuit and electronic equipment, and the method comprises the steps: determining a first triangular current control phase, a first clamping control phase and a first current interruption control phase according to the size sequence of amplitude absolute values of A-phase, B-phase and C-phase input voltages, the first characteristic parameter of the three-phase power conversion circuit is utilized to generate first to third control signals corresponding to the first characteristic parameter; after the current signal period, the first triangular current control phase is adjusted to be a second clamping control phase in response to gradual increase of the input voltage absolute value of the first triangular current control phase; adjusting the first clamping control phase to a second triangular current control phase; and fourth to sixth control signals corresponding to the second clamping control phase, the second triangular current control phase and the first current interruption control phase are respectively generated by using the second characteristic parameter. Through the above mode, the switching control method provided by the invention can effectively reduce the switching loss, and reduces the total harmonic distortion rate.

A voltage controller (204) detects (604) a voltage spike (244) in an electrical signal received from an electrical power source (208). The voltage controller (204) is implemented using a single-loop control system in a stationary reference frame. The electrical signal includes voltage harmonics caused by a non-linear or unbalanced load (256). The voltage controller (204) includes a phase-compensated harmonic regulator (220) that regulates the voltage harmonics present in the electrical signal and receives a feedback voltage (240) of the single-loop control system. The feedback voltage (240) is a delayed version of an instantaneous voltage (236) of the electrical signal. The instantaneous voltage (236) is sub-transiently stabilized into a steady-state voltage (232) based on the feedback voltage (240). Sub-transiently stabilizing the instantaneous voltage (236) is performed within a single cycle after the voltage spike (244) is detected (604). The steady-state voltage (232) has a total harmonic distortion less than a threshold total harmonic distortion and the steady-state voltage has a balanced sinusoidal waveform.

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

The invention discloses a rotor composite magnetic pole of an axial magnetic flux permanent magnet synchronous motor, which comprises a plurality of sector-shaped magnetic pole units uniformly distributed on one surface of a rotor core along the circumferential direction, and each magnetic pole unit comprises three sector-shaped permanent magnets with equal thickness and different magnetic properties, the second permanent magnet and the third permanent magnet are symmetrically arranged by connecting one right-angle side with the two isosceles sides of the first permanent magnet, the residual magnetic induction intensity of the three permanent magnets is low-high-low arrangement, and the connecting faces of the second permanent magnet and the first permanent magnet and the connecting faces of the third permanent magnet and the first permanent magnet are inclined faces inclined to the magnetizing direction. And gaps are formed between adjacent magnetic pole units. The rotor composite magnetic pole is combined with high and low residual magnetism materials through the inclined plane connection structure, so that the magnetic flux between the magnetic poles realizes smooth and continuous transition, the total harmonic distortion rate and the torque ripple of the air gap flux density can be effectively reduced, the noise is remarkably improved, and the overall efficiency and stability of the motor are further improved; and in combination with clear parameterization design, rapid optimization can be conveniently carried out in combination with an intelligent algorithm.

The utility model belongs to the technical field of electronics, and particularly relates to a low-harmonic rectification control circuit which remarkably counteracts low-order harmonics such as five-order harmonics and seven-order harmonics through multi-phase superposition of a phase-shifting transformer, the total harmonic distortion (THD) is lower than 5%, the environmental protection requirement of high-power industrial equipment for a power grid is met, and a control cable has the advantages of low harmonic pollution, low cost and the like. The DSP main control chip is combined with the digital timer, and the serial-to-parallel circuit only needs one PWM pin and three GPIO pins, so that the DSP resource occupation is reduced; the gating circuit adopts a general multiplexer (74HC4051D), so that the hardware complexity is reduced; the drive circuit realizes strong and weak current isolation through the isolation transformer, prevents high-voltage interference from damaging a control chip, improves the system safety, and reduces the maintenance cost of the circuit.

The invention relates to the technical field of grid-connected equipment impedance control, in particular to a wide-frequency-domain self-adaptive admittance control method and system considering the frequency coupling effect, and the method comprises the steps: building a wide-area admittance remodeling control loop considering the frequency coupling effect, comprising a virtual impedance control branch, a DC voltage loop control branch, a current loop forward control branch and two virtual impedance feed-forward branches. Selecting a reference virtual resistor based on a converter fundamental wave reactance coefficient, and determining a maximum variable admittance remolding adjustment coefficient and a numerical range of a reference virtual inductor through grid-connected converter GCC self-stability constraint; the variable admittance remolding adjustment coefficient is automatically adjusted based on the total harmonic distortion (THD) of the voltage component, the value of the amplification coefficient is determined based on the constraint of the maximum adjustment coefficient, and the admittance self-adaptive control of the converter is realized. And the method also has the advantages of broadband adjustment characteristic, simple admittance parameter setting, adaptive admittance adjustment and the like.

The invention discloses a harmonic injection type active damper output impedance design method. A sliding-mode observer is used, related voltage and current signals of a power grid are collected and serve as input after coordinate transformation processing, a to-be-estimated high-frequency harmonic current value is initialized firstly, then an error between an estimated value and an actual value is calculated to construct a sliding-mode surface, whether a preset stability condition is met or not is judged, and if yes, a corresponding control strategy is triggered to suppress disturbance and buffeting; and continuously updating the estimated value, finally outputting an accurate high-frequency harmonic current reference value, and meanwhile, feeding back the output to an error calculation link to form closed-loop iteration, thereby realizing real-time tracking and accurate estimation of the high-frequency harmonic current of the grid-connected converter system. In combination with dq impedance analysis, output impedance and a control strategy of the active damper are deduced, so that output current of the damper can accurately offset high-frequency harmonic waves of a grid-connected converter system, system oscillation is effectively suppressed, total harmonic distortion of grid-connected current is reduced, electric energy quality is improved, and stable operation of the grid-connected converter system under different working conditions is ensured.

The invention relates to a two-stage converter circuit comprising a first stage that is configured to provide power factor correction and a second stage that is configured to provide electric isolation and fixed voltage-to-voltage conversion. The converter circuit is configured to fulfil input requirements (e.g., total harmonic distortion (THD), power factor (PF) etc.) and apply isolation by means of a self-oscillating converter. Thereby efficiency can be improved and costs reduced for LED drivers or other driver circuits that require an isolated output.