41 results about "Sinusoidal current" patented technology

The invention discloses a battery peak power prediction method and system based on multi-modal data coupling mapping, and relates to the technical field of lithium ion power battery management. The method comprises the following steps: acquiring electrochemical parameters and thermophysical parameters of a battery to be detected, and constructing a single-particle thermal coupling model; injecting a plurality of sinusoidal current disturbances with different frequencies into the battery to be detected, synchronously sampling voltage and current, and extracting an impedance real part under each frequency; mapping an impedance real part and the decomposed total DC internal resistance according to a mapping relation among impedance, temperature and aging; performing closed-loop correction by using an extended Kalman filter to obtain a dynamic total internal resistance; and calculating the maximum allowable current according to the dynamic total internal resistance based on the current open-circuit voltage and cut-off voltage constraint, and further outputting the instantaneous peak power of the load end. According to the method, accurate online estimation is carried out on the instantaneous peak power of the battery under the conditions of the full life cycle and the full weather of the vehicle.

The invention provides a non-power-cut test method for mutual inductance parameters of a power transmission line under excitation of different-frequency signals and a related device, and solves the problems of difficulty in accompanying stop and high safety risk of adjacent lines. The method comprises the following steps: selecting one circuit in the same corridor for power failure, connecting the head end with an induced electricity suppression device, and performing three-phase short-circuit grounding at the tail end; injecting a different-frequency sinusoidal current of 45-55Hz into the power failure line; the synchronous measurement device collects head and tail voltage and current of a running line based on a satellite synchronous clock; extracting pilot frequency signals through two-stage notch filtering and Fourier transform; and different-frequency zero-sequence self-impedance and mutual impedance are calculated and converted into power-frequency impedance. According to the invention, accurate test without power failure can be realized, and safety and power supply reliability are guaranteed.

The invention provides a motor detection method and device, electronic equipment and a storage medium, and the method comprises the steps: controlling a motor to operate under a first identification parameter, and calculating a phase resistance value of the motor under the first identification parameter; controlling the motor to operate under a second identification parameter, and collecting a sinusoidal current response signal of the motor under the second identification parameter; calculating a d-axis inductance value and a q-axis inductance value based on the sinusoidal voltage excitation signal, the sinusoidal current response signal and the phase resistance value; the motor is forcibly dragged in a current-frequency ratio control mode, so that the rotating speed of the motor is increased to the target rotating speed; and calculating the flux linkage coefficient by combining the steady-state voltage and the current value of the motor at the target rotating speed with the d-axis inductance and the q-axis inductance. According to the method, the detection precision of the motor parameters can be improved.

The invention relates to the technical field of circuit board detection, in particular to a printed circuit board drilling quality detection method and device, and the method comprises the steps: injecting sinusoidal current signals with preset frequencies into a plurality of test points of a to-be-detected drilling region of a printed circuit board, extracting impedance values under each frequency component, and calculating the drilling quality of the printed circuit board; constructing an equivalent impedance spectrum containing a real part and an imaginary part according to the impedance value; according to the interlayer structure and the equivalent impedance spectrum of the printed circuit board, calculating equivalent resistance and equivalent capacitance of the drilling area to be measured to form a characteristic parameter set; comparing the data of each grid point in the characteristic parameter set with a preset threshold value, and integrating the grid points exceeding the preset threshold value to generate a defect state mark; and performing electrical topology constraint on the defect state mark to generate a defect positioning result. According to the invention, hidden defects in the drill hole and interlayer structures can be deeply detected, the electrical performance of the drill hole can be comprehensively evaluated, and accurate defect positioning and state marking can be provided.

The application discloses an online permanent magnet flux identification method of a permanent magnet synchronous motor considering cross coupling effect and belongs to the permanent magnet flux identification technology of the permanent magnet synchronous motor. The application aims at solving the problem that the existing permanent magnet synchronous motor flux identification method does not consider the cross coupling influence of the motor, thereby causing the error of the flux observation result to be large. The application comprises the following steps: under the online stable working condition of the motor, injecting a sinusoidal current signal into the dq axis of the motor to realize three-phase direct current signal injection; calculating the motor stator resistance; injecting two groups of direct current bias voltage into the d-axis of the motor through the current loop, establishing three motor voltage equations, and then obtaining two motor voltage difference equations which eliminate the flux terms; solving to obtain the motor d-axis self-inductance L d and the motor dq-axis mutual inductance L dq ; establishing the dq-axis voltage equation considering the cross coupling, calculating the motor permanent magnet flux based on the motor stator resistance, the motor d-axis self-inductance L d and the motor dq-axis mutual inductance L dq . The application is used for the online identification of the permanent magnet flux of the permanent magnet synchronous motor.

The invention relates to a semiconductor lamp control method and an intelligent electric appliance, which are applied to the field of intelligent electric appliances, and the semiconductor lamp control method comprises the following steps: driving a semiconductor lamp to illuminate through a high-frequency sine wave current signal; the high-frequency sine wave current signal is obtained by modulating an original current signal for driving the semiconductor lamp to illuminate; collecting a current output signal output by the photoelectric sensor when the semiconductor lamp illuminates; determining the attenuation degree of the semiconductor lamp through a lock-in amplifier based on the phase difference between the high-frequency modulation current signal and the current output signal; and controlling the semiconductor lamp based on the attenuation degree. According to the invention, the problem of illumination response delay caused by aging of the semiconductor lamp is solved.

The invention discloses a pulsating voltage-based current transformer secondary circuit disconnection fault detection method, and belongs to the technical field of power distribution network fault detection. According to the invention, the correlation between the real-time voltage signal induced by the voltage transformer and the reference voltage is considered on the basis of the current transformer secondary circuit disconnection difference current criterion; the method has the core effects that the current transformer secondary circuit disconnection fault and the high-resistance grounding fault of the power transmission current are distinguished according to the pulsation rhythm with the specific length in the correlation coefficient between the real-time voltage signal and the reference voltage information, so that the small-amplitude sinusoidal current distinguishing capability of a power transformation secondary system device is improved; and the detection accuracy of the secondary circuit disconnection fault of the current transformer of the power transmission line is greatly improved.

The application relates to a method and device for calculating frequency domain amplitude and phase angle in a memristor array, wherein the method comprises the following steps: obtaining a time domain input signal corresponding to a target memristor array, and calculating a cosine mixing signal and a sine mixing signal based on the time domain input signal, a preset cosine signal and a sine signal; applying the cosine mixing signal and the sine mixing signal to corresponding row lines of the target memristor array respectively, so as to calculate cosine current data and sine current data based on a discrete Fourier transform matrix of the corresponding row lines; obtaining current information of each frequency point in the target memristor array based on the cosine current data and the sine current data, and reading phase information and amplitude information corresponding to each frequency point in the current information through a preset phase discriminator and a peak value detector respectively. Thus, the problems that the prior art cannot directly calculate the amplitude and the phase without increasing additional hardware overhead and operation delay, and the efficiency of frequency domain amplitude and phase angle calculation is greatly affected are solved.

This invention discloses a flexible low-frequency-flexible DC hybrid power transmission system and its control method. The hybrid power transmission system of this invention includes a receiving-end converter station, a low-frequency AC renewable energy power station, and a high-frequency DC renewable energy power station. The power conversion unit of the receiving-end converter station adopts a modular design. Each power module is combined in series / parallel to form the power frequency AC, low-frequency AC, and high-voltage DC ports of the converter station. Each port is connected to the power frequency main grid, the low-frequency AC port, and the DC renewable energy power station through transmission lines, respectively. The receiving-end converter station achieves voltage stability of the low-frequency AC port and the high-voltage DC port, sinusoidal current of the power frequency AC port, and DC bus voltage stability of each power module through multi-level control at the system level, bridge arm level, and module level. This invention achieves coordinated operation of flexible low-frequency and flexible DC power transmission modes, is suitable for efficient transmission from renewable energy power stations at different distances, and realizes integrated operation of different types of converter stations.

This invention discloses a double-layer mutually inducted coupled planar eddy current detection sensor. First, an external excitation source provides AC power input to the detection coil layer, causing the LC resonator, composed of the detection coil and a parallel resonant capacitor, to resonate, generating a sinusoidal current and forming a primary magnetic field. When the test piece is in the primary magnetic field, eddy currents are generated on its surface, creating a mutual inductance effect with the sensing coil. Changes in lift-off or disturbances in the flow direction of eddy currents at defects lead to changes in the mutual inductance coefficient, causing a change in the equivalent inductance of the sensing coil and a change in the resonant frequency. Finally, the resonant frequency is detected and extracted to obtain the detection signal. Similarly, a set of detection signals is also extracted from the reference coil. By comparing the changes in the signals detected by the reference coil and the detection coil, lift-off and defect signals are separated to obtain defect information.

The application discloses a kind of high-power IGBT rectifying system and method, it is related to the technical field of IGBT rectification, including active front-end rectification main circuit is constructed;Integrated dc side hybrid harmonic modulation auxiliary circuit;Multiple delay signal elimination operation is carried out to the signal obtained by sampling, filter harmonic interference signal, the frequency and phase of grid fundamental voltage are locked by phase-locked loop;Establish the control structure of voltage outer loop and current inner loop, generate the instruction amplitude of net side active current and ideal sine current reference waveform, and real-time control IGBT in active front-end rectification main circuit;Actual input current of net side is analyzed in real time by fast fourier transform, and residual harmonic component is identified;Realize the feedback management of regenerative energy.The application proposes a kind of active front-end IGBT rectification method and system with high adaptability of fusion type, which can operate stably under grid voltage distortion conditions, and realize deep harmonic suppression and high efficient energy bidirectional flow.

A muscle and bone dredging instrument disclosed by the present invention comprises a host and a pole piece, the host is provided with a display screen and a host power line, the host is provided with an adjusting key, a display lamp, a plurality of keys and a wire plugging hole, the pole piece is provided with an electrode socket, one end of the electrode socket is provided with a pole needle, and the other end of the electrode socket is provided with a wire. The invention relates to the technical field of physiotherapy equipment, and the core principle is that positioning electric energy is output through a body-controlled high-energy biological electro-therapeutic apparatus and is conducted to the body of a patient by a professionally trained electro-therapist through self-adjustment of current intensity, and sine wave current matched with human body cell bioelectricity waveform is utilized to excite essence and qi to dredge the channels and collaterals, so that the body-controlled high-energy biological electro-therapeutic apparatus can be used for treating body diseases. Therefore, the treatment effect that pain is not caused by general communication is achieved.

This invention discloses a method, apparatus, device, and storage medium for early warning of battery capacity drops. The method includes: detecting particulate crack features in a target battery based on acoustic emission signals to generate a crack event rate time series; measuring the electrochemical impedance spectroscopy of the target battery based on a multi-frequency sinusoidal current excitation signal, and determining a crack sensitivity index time series based on the electrochemical impedance spectroscopy; time-series fusion of the crack event rate time series and the crack sensitivity index time series to construct a dual-feature time series matrix; and quantitative identification of the dual-feature time series matrix based on preset crack event rate thresholds and crack sensitivity index thresholds to determine whether the target battery has entered the early stage of capacity drops. This invention can accurately determine whether a target battery has entered the early stage of capacity drops, thereby achieving quantitative characterization and reliable early warning of battery capacity abrupt changes.

A current mode sinusoidal oscillator includes a current amplifier with distinct current input and four output terminals. The amplifier includes a current input terminal X, a first and a second negative current feedback terminals Ifo1 and Ifo2, along with a positive current output terminal Iop and a negative current output terminal Ion. The oscillator is characterized by a first feedback path that transmits a portion of a current at the first negative current feedback terminal Ifo1 to the current input terminal X of the oscillator. Additionally, a second feedback path, interlinking Ifo2 and X, comprises a three-stage phase lag network designed to confer a phase shift of negative 180 degrees to the current signal at a frequency of oscillation determined by capacitor and resistor values of the three-stage phase lag network. A load is connected between Iop and Ion, which receives the sinusoidal current at the frequency of oscillation.

The permanent magnet synchronous motor parameter identification method based on fuzzy adaptive control has the following steps: inputting a frequency value f0, an amplitude value, and a bias value of a d-axis current signal at a set angle, performing PI setting of a current loop, and obtaining K p , K i of the current loop; giving a d-axis step current instruction, adopting a mean value and difference method to obtain an identification resistance; giving a d-axis sinusoidal current instruction, and utilizing a least square method with a forgetting factor to obtain an identification d-axis inductance; giving a q-axis sinusoidal current instruction, and obtaining an identification q-axis inductance according to a q-axis voltage, a q-axis feedback current and the identification resistance; and giving a q-axis step current instruction, and obtaining a flux according to the q-axis voltage, the q-axis feedback current, a motor rotating angular velocity and the identification resistance. The method is a closed-loop offline parameter identification method, and has the advantages of simple and reliable identification process, universality, controllable current, high safety, no motor rotation except for identification of the flux, and applicability to different occasions.

This invention relates to a rapid heating device for lithium-ion batteries that also supports EIS measurement. It includes a battery module, a DC / DC voltage regulator module, a heating module, a heating control system, and an EIS detection and control system. The DC / DC voltage regulator module integrates an isolation transformer, switching components, an independent control logic unit, and an energy storage capacitor to form an isolated boost structure, achieving voltage boost and maintaining stable high-voltage DC bus voltage. The heating module includes an H-bridge structure, a heating inductor, and a heating capacitor. It achieves two operating modes through a switching control strategy: in heating mode, it generates AC current to heat the battery module; in EIS measurement mode, it generates sinusoidal currents of different frequencies to facilitate EIS measurement. The heating control system adjusts heating parameters in stages. The EIS detection and control system obtains EIS data by detecting the voltage response of the battery module, enabling the detection of the battery's health status. This invention integrates low-temperature rapid heating with EIS measurement, providing precise temperature control and ensuring battery performance and safety.

The invention relates to an LLC transformer temperature prediction and control method, system, device and medium, and the method comprises the steps: obtaining the structure parameters and material attributes of an LLC transformer, and carrying out the parameterized three-dimensional modeling, and obtaining a transformer three-dimensional geometric model comprising complete material attributes; non-sinusoidal current waveforms of the LLC transformer during working are acquired through circuit simulation, key characteristic parameters of the current waveforms are extracted, and magnetic core loss is calculated by utilizing an IGSE formula based on the key characteristic parameters and material attributes; acquiring environment parameters of an environment where the LLC transformer is located, and calculating heat transfer key parameters between the surface of the LLC transformer and air based on the environment parameters; based on the magnetic core loss and the heat transfer key parameters, performing steady-state thermal simulation and transient thermal simulation by using the three-dimensional geometric model of the transformer to obtain a temperature distribution condition, and generating an LLC transformer temperature management strategy based on the temperature distribution condition; the system, the equipment and the medium are used for realizing the method. Compared with the prior art, more accurate transformer temperature prediction is realized.

The application provides a motor detection method and device, electronic equipment and storage medium, wherein the method comprises: controlling the motor to run under a first identification parameter, calculating the phase resistance value of the motor under the first identification parameter; controlling the motor to run under a second identification parameter, collecting the sinusoidal current response signal of the motor under the second identification parameter; based on the sinusoidal voltage excitation signal, the sinusoidal current response signal and the phase resistance value, calculating the d-axis inductance value and the q-axis inductance value; using the flow frequency ratio control mode to force the motor to drag, so that the rotating speed of the motor is increased to a target rotating speed; collecting the steady-state voltage and current value of the motor under the target rotating speed, and combining the d-axis inductance and the q-axis inductance, to calculate the flux linkage coefficient. Through the above method, the detection accuracy of the motor parameters can be improved.

The claw-pole stepping motor with a built-in drive chip comprises a rotor assembly (4) and a stator assembly (5), the stator assembly (5) including a housing (51) and a skeleton assembly (55) inside the housing (51), an opening (511) is provided on one side of the housing (51), an outlet box (52) is connected to the opening (511), a circuit board (2) is provided between the outlet box (52) and the skeleton assembly (55), and the circuit board (2) and the skeleton assembly (55) are connected by pins (53), and a drive control chip (21) and chip peripheral elements (22) for adjusting and controlling the drive current waveform are integrated on the circuit board (2). The stepping motor has the characteristics of low overall production costs, relatively high connection reliability, and small vibration. It is also driven by a sinusoidal current using high-frequency pulse-width modulated voltage pulses according to the required drive current waveform, and each pulse of the output current can be precisely controlled, resulting in smooth operation, small vibration, low noise, and stable output torque.

The invention belongs to the field of geophysical exploration, and relates to a well frequency domain electromagnetic method three-dimensional anisotropic resistivity robust imaging method, which comprises the following steps of: adopting a well probe rod with a built-in three-axis orthogonal transmitting coil and a three-component receiving sensor to perform point-by-point movement measurement at a preset interval along a well axis; at each measuring point, the probe rod in the well is stopped, and the three orthogonal emission shafts are independently excited in sequence; in the excitation process of each transmitting shaft, a plurality of sine wave currents with specific frequencies are introduced in sequence, the transmitting magnetic moment is recorded, and the actually measured electromagnetic response induced in the receiving coil is synchronously collected; according to the method, actually measured electromagnetic response is preprocessed, inversion is performed by adopting a Bayesian geostatistics inversion method based on posterior confidence constraint in combination with actually measured electromagnetic response data, anisotropic resistivity distribution in a three-dimensional space around a well is obtained, and the robustness of frequency domain electromagnetic imaging in the well is effectively improved.

This application discloses a method, apparatus, device, and medium for parameter identification of a synchronous motor. The method includes: obtaining the steady-state value of the synchronous motor under a given voltage and the measured value of the bus voltage by varying the carrier frequency; obtaining the stator resistance of the synchronous motor and the saturation voltage error of the inverter using a target converter circuit model of the inverter and the synchronous motor and multiple sets of measured values; injecting a low-frequency sinusoidal current into the synchronous motor, and determining the current corresponding to the minimum ratio of the third harmonic amplitude to the fundamental amplitude of the synchronous motor at the given voltage as the bias current identification result of the inverter; when the direct and quadrature axes of the synchronous motor have saturation characteristics, obtaining the maximum peak point of its response current spike under the second harmonic and the zero-crossing point of the fundamental wave, injecting positive and negative voltage pulses into these two points respectively, and determining the type of synchronous motor and the direct and quadrature axis inductance based on the peak value of the response current. This method can improve the accuracy of synchronous motor parameter identification.

The utility model provides a power amplification circuit and radio frequency steam ablation equipment, relates to the technical field of medical equipment, is used for solving the technical problems that in the prior art, a power amplification circuit in the radio frequency steam ablation equipment is large in switching loss, complex in control and difficult in synchronization, and comprises a zero-voltage switch module and a resonance filtering module, the zero-voltage switch module controls a signal to drive the controllable switch to be switched on and switched off periodically, and the input direct current is converted into pulse current; a resonant element in the zero-voltage switch module is used for enabling the voltage at the two ends of the zero-voltage switch to approach to zero when the zero-voltage switch is switched on or switched off; and the resonant filtering module converts the pulse current into a sinusoidal current with a target frequency, and transmits the sinusoidal current to the radio frequency steam ablation catheter, so that the power amplification circuit can realize zero-voltage turn-on or turn-off, the switching loss in the power amplification circuit is reduced, the zero-voltage switch module only needs to be provided with a controllable switch, and the control is relatively simple.

The application discloses an active front-end rectifier and a prediction control method thereof, and the method comprises the following steps: according to a voltage model of a three-level active front-end rectifier, calculating active power and reactive power of a power grid according to instantaneous power theory; according to the voltage model, combining the active power and the reactive power, calculating a power gradient; converting the power gradient into a second-order state space equation, predicting the control input of the active front-end rectifier by using a super-helix observer, and obtaining the input voltage of the active front-end rectifier according to the predicted control input and the grid-side voltage; based on the input voltage, obtaining an optimal voltage vector by using a limited set model prediction control framework, and controlling the active front-end rectifier based on the switching state corresponding to the optimal voltage vector. The method combines power gradient modeling, super-helix observer disturbance compensation and limited set prediction control, so that the rectifier overcomes the influence of parameter mismatch, and realizes high-sinusoidal current, stable DC voltage and power tracking control.

A system for controlling a magnetic microdevice to move within a fluidic environment, comprising an imaging device, a multi-axis electromagnet for generating a magnetic field based on sinusoidal current signals, and a controller for controlling the multi-axis electromagnet based on a machine-learning model, and wherein for training the machine-learning model, the controller is configured to receive images of the fluidic environment and the magnetic microdevice from the imaging device, determine a state comprising position information of the magnetic microdevice based on the images, calculate a measure of performance associated with a first set of sinusoidal current signals previously inputted to the multi-axis electromagnet, wherein the calculated measure of performance is used to adjust parameters of the machine-learning model, and generate based on the position information and the first set of sinusoidal current signals using the machine-learning model, a second set of sinusoidal current signals as inputs for the multi-axis electromagnet.

One example includes a current distribution system. The system includes at least one resonator spine that propagates a sinusoidal current. The system also includes at least one resonator rib conductively coupled to the at least one resonator spine and arranged as a standing wave resonator with respect to the sinusoidal current. Each of the at least one resonator rib can have a length from a first end corresponding to the conductive coupling to a second end that corresponds to a half wavelength of the sinusoidal current.

Systems and methods relating to control systems for DC / AC inverters that receive power from photovoltaic based renewable energy resources. When the DC / AC inverters are operated in on-grid mode, the DC / AC inverters and the DC / DC control system operate to provide on-grid functions such as maximum power point tracking (MPPT) and DC-bus voltage regulation. When in off-grid mode, the DC / AC inverter and the off-grid control system regulates the resulting AC voltage from the DC / AC inverter to be within a pre-set range. The off-grid control system is based on differential geometry and uses a Lie Group controller for setting a frequency reference signal. The frequency and current amplitude reference are used to generate a sinusoidal current reference signal which is then tracked by a current controller. The current controller controls the switches in the DC / AC inverter to regulate the AC voltage.

The present application relates to the technical field of battery management, and more particularly to a solid-state battery thermal runaway early warning method and system based on electric-magnetic dual-mode fusion. The method comprises injecting a preset frequency sinusoidal current disturbance signal into a to-be-tested solid-state battery and synchronously collecting the voltage response signal of the battery; performing time-frequency transformation on the voltage response signal to obtain a time-frequency domain representation; calculating an energy concentration index and a time continuity index based on the time-frequency domain representation; determining whether the first early warning condition is met based on the energy concentration index and the time continuity index, and triggering the first stage early warning; after triggering the first stage early warning, starting non-contact monitoring of the external magnetic field of the solid-state battery; and determining whether the second early warning condition is met based on the monitored magnetic field data, and triggering the second stage early warning. The present application can realize early, rapid and non-destructive early warning of thermal runaway.

The application discloses a battery charging circuit and device, the circuit comprises: the input end of PFC module is used for accessing grid voltage signal, and the output end is used for directly connecting the battery to be charged; the reference current generation module generates unit sine wave signal by using phase information of the grid voltage signal, and generates instantaneous sine current reference signal by combining target current amplitude reference signal; the current feedback compensation module calculates current error signal and carries out proportional integral adjustment to obtain current compensation control quantity; the drive generation module modulates and generates PWM drive signal according to duty cycle control signal at least comprising the current compensation control quantity and transmits the PWM drive signal to the PFC module; the PFC module controls the on-off of the internal power switch tube in response to the PWM drive signal, so as to deliver low-harmonic electric energy to the battery. Through the PFC charging structure without output voltage closed loop, the application can shorten the energy conversion link, reduce the control complexity, and reduce the cost and volume.

The application discloses an asymmetric axial electromagnetic force wave calculation method of an axial magnetic field permanent magnet memory motor, which mainly comprises the following steps: determining a solving coordinate system, respectively establishing Poisson equations and Laplace equations for the motor according to different solving regions of air gaps and Halbach array permanent magnets, solving static axial air gap magnetic flux density and circumferential air gap magnetic flux density according to boundary conditions that should be met by an open-circuit magnetic field analytical model on the basis of obtaining a Laplace general solution, calculating a Halbach array permanent magnet magnetic motive force during motor operation, respectively calculating a single-phase winding generated magnetic motive force and a three-phase winding generated magnetic motive force when the motor is supplied with three-phase symmetrical sinusoidal currents, and deducing and calculating a motor axial air gap magnetic field distribution formula in the case of considering air gap permeability. In the case of ignoring air gap saturation, axial electromagnetic force acting on a unit area of the axial magnetic field permanent magnet memory motor is calculated according to Maxwell tensor equations.

This invention provides a method for controlling the excitation current of a doubly-fed induction generator (DFIG) in synchronous mode. The method includes: dividing the entire DFIG operation into two modes: synchronous speed control mode and asynchronous speed control mode; when the DFIG operates near synchronous speed, it enters the synchronous speed excitation current control mode, employing optimized excitation current control; after entering synchronous speed, based on the combined judgment of the rotational speed n and the instantaneous values ​​of the rotor three-phase currents, the method ensures that the duty cycle of the devices in the memory is the same or similar for multiple cycles, serving as a condition for starting the rotor current; and when the per-unit value of the three-phase rotor current is less than i = k, a preset triangular carrier wave or sinusoidal current is applied to the three-phase rotor current to ensure dynamic adjustment of the device duty cycle. This invention can improve the problems of heat generation / fatigue caused by the switching devices of the DFIG rotor converter maintaining the same duty cycle for a long time under synchronous speed, thus improving the reliability of the converter.