71 results about "Modulation index" patented technology

The invention provides a solid-state transformer. The solid-state transformer comprises a first-stage circuit, a first direct-current bus and a second-stage circuit, the first-stage circuit structure is used for receiving alternating-current electric energy and converting the alternating-current electric energy into first direct-current electric energy. The first DC bus is electrically connected to first DC electric energy. The second-stage circuit is electrically connected to the first-stage circuit through a first DC bus, and is configured to perform isolated step-down DC / DC conversion on the first DC electric energy to generate second DC electric energy. The first stage circuit is configured to operate with a modulation index greater than 1, and the modulation index is defined as a ratio of twice an AC voltage provided by the AC power to a voltage on the first DC bus.

The invention discloses a modulation index adjusting method and device of NFC (Near Field Communication) equipment and the NFC equipment, which are used for improving the adjustment efficiency of a modulation index and enabling the modulation index to be within a protocol requirement range. The method comprises the following steps: acquiring an electrical parameter reflecting the load effect of the NFC chip; according to the electrical parameter, calculating an equivalent conduction resistance value which needs to be configured for the power amplifier; and configuring the equivalent conduction resistance value of the power amplifier according to the equivalent conduction resistance value needing to be configured, so that the modulation index of the carrier envelope transmitted by the signal transmitting circuit after configuration is within a protocol requirement range.

This invention discloses an adaptive fault-tolerant control method for a three-level ANPC inverter. Specifically, based on the influence of a faulty switching transistor on the output voltage vector, the inverter's fault-tolerant modes are classified into zero-level loss and zero-level retention fault-tolerant modes. The maximum modulation index of the inverter's output voltage vector is calculated under both fault-tolerant modes to determine whether the inverter system needs derating. For the zero-level retention fault-tolerant mode, a model predictive current control strategy with duty cycle modulation is adopted, utilizing a virtual zero-voltage vector synthesis method to solve the inverter's midpoint voltage imbalance problem. For the zero-level loss fault-tolerant mode, a cost function representing the fault-tolerant control performance index is designed, and a neural network is used to optimize the weight factors of the cost function. This invention achieves adaptive fault-tolerant control for open-circuit faults in inverters by adopting corresponding model predictive control optimization methods for different fault-tolerant modes, thereby improving the reliability of the inverter system.

An apparatus includes an unfolder with three input terminals connected to a three-phase AC power source and three output terminals, p-terminal, o-terminal, and n-terminal, and a three-port converter connected to the unfolder and feeding a direct current (“DC”) load. The three-port converter includes input capacitors. A feedback control loop includes outputs of a p-terminal modulation index derived from a difference between p-terminal current and a p-terminal reference current and an n-terminal modulation index derived from a difference between n-terminal current and an n-terminal reference current. A feedforward control loop outputs an emulated p-terminal current and an emulated n-terminal current derived from differences between DC-link voltages and ideal DC-link voltages. A duty cycle controller is configured to generate duty cycles controlling switches of the three-port converter derived from the modulation indexes and the emulated currents.

A method is provided for reducing common mode voltages in a system that includes an inverter connected to a motor by a long cable by controlling switches of the inverter to generate voltage vectors that emulate a three-phase sinusoidal waveform by switching between adjacent active vectors and active vectors that are separated by 180 degrees, determining whether a phase angle of the vectors is increasing or decreasing, determining a decision angle within the sector which is a function of a duty cycle offset and a modulation index; and applying duty cycle manipulation rules, including: responding to an increasing phase angle that is less than the decision angle by setting a duty cycle of the adjacent active vectors to a duty cycle high value; and responding to an increasing phase angle that is greater than 60 degrees minus the decision angle by setting the duty cycle to a low value.

Methods, systems, and devices for wireless communications are described. A first wireless device may receive a signal including multiple sets of bits, where each set of bits of the multiple sets of bits is associated with either a first group or a second group based on a respective modulation index for each set of bits. Each set of bits may map to one or more additional bits based on an association of each set of bits with the first group, the second group, or both. The first wireless device may decode either or both of a first message formed at least partially by the one or more additional bits or a second message formed at least partially by respective sets of bits associated with the second group. Each of the first and second messages may be for different channels or for different wireless devices.

The utility model discloses a radio frequency signal jig for a non-radio frequency test seat, which is characterized in that a tunable coupling plate is correspondingly arranged on the surface of an upper cover of the jig and at the projection position of an onboard antenna, and the area of the tunable coupling plate is adjusted to be the same as the projection area of the onboard antenna. And the distance between the tunable coupling plate and the onboard antenna is adjusted to be within a set distance range, and the load impedance of the radio frequency link is adjusted to be close to an impedance point by 50 ohms, so that the frequency response characteristic of the radio frequency signal is changed, impedance matching is realized, the anti-interference capability of the onboard measurement radio frequency signal is improved, and the mismeasurement proportion of a radio frequency modulation index is reduced. Besides, the tunable coupling plate is also connected with the impedance matching circuit, the inductance value or capacitance value of a tuning element in the impedance matching circuit is adjusted, the matching tuning impedance is replaced to enable the tunable coupling plate to be coupled and parasitic, and the impedance track of the radio frequency signal jig is moved to a 50-ohm matching point, so that better impedance matching is realized, and the impedance matching precision is improved. And the test precision and efficiency are further improved.

A technique for recursively determining the modulation index for controlling a DC-AC inverter is disclosed. The modulation index can first be selected. The input voltage to the power inverter can be measured. Based on the input voltage and the selected modulation index, the output voltage of the power inverter may be estimated. The output current of the power inverter can be measured. Using the estimated output voltage and the measured output current, the active power and reactive power can be determined. Using the active power and reactive power, the updated modulation index can be determined. The updated modulation index coefficient can be used to generate a pulse-width modulated signal used to control the power inverter.

The application provides a control system and a control method of an LLC resonant induction heating power supply. The LLC resonant induction heating power supply heats a load through a half-bridge inverter circuit. The control system comprises a modulation unit and an odd harmonic control unit. The modulation unit is used to determine a target modulation index and a fundamental frequency, and to realize an output frequency adjustable high-frequency alternating square wave by controlling the switching of each power device of the half-bridge inverter circuit. The waveform of the high-frequency alternating square wave has a half-wave symmetric structure with a fundamental period as a cycle. The odd harmonic control unit is used to predict an optimal switching angle combination of each power device under the condition of meeting an odd harmonic suppression target. The modulation unit generates a modulation signal for controlling the switching of each power device based on the optimal switching angle combination. The application can significantly improve the harmonic suppression effect of a high-frequency induction heating power supply under a dynamic load.

Control system (24) for controlling the operation of a multiphase electrical machine (19), comprising: a signal generator (210) configured to generate a number n of duty cycle signals of a pulse width modulation (PWM) scheme as a combination of a continuous PWM scheme and a non-continuous PWM scheme, the combination being based on a value of a mixing coefficient Σ; wherein the signal generator (210) is configured to use each of the duty cycle signals to control the switching of a DC power to a corresponding phase of the multiphase electrical machine (19); wherein the signal generator (210) is configured to use a mixing function to determine a relative weighting of both the continuous PWM scheme and the non-continuous PWM scheme to generate the number n of duty cycle signals;wherein the mixing function is calculated on the basis of a difference between the value of the mixing coefficient γ and two thresholds a1, a2; and wherein the duty cycle signals are generated via the combination of the continuous PWM scheme and the discontinuous PWM scheme, based on the fact that the value of the mixing coefficient γ is greater than or equal to a first threshold a1 and less than a second threshold a2, where the second threshold a2 is greater than the first threshold a1; characterized in that n is an integer greater than 3 and that the mixing function determines the mixing coefficient γ as a function of the modulation index mi and a phase current Is using the following formula: γ(mi,Is)={0.50≤γ; <a10.5×(1−&lgr;−a1a2−a1)a1≤&lgr;<a20a2≤&lgr;<1wobei &lgr; eine Zwischenvariable ist, die definiert ist durch:&lgr;(mi,Is)=b⋅IsIsmax+(1−b)⋅mi,0≤b≤1 where b is a tunable constant and Ismax is the maximum current of the multiphase electric machine (19).;

A common-mode voltage generation method is provided and comprises: obtaining a DC voltage, AC voltages, and a modulation index of a DC / AC converter; generating an injection instruction of a common mode voltage for pulse width modulation based on the DC voltage, the AC voltages, the modulation index, and an adjustable modulation control factor; and providing the injection instruction to the converter, in which the injection instruction is used to instruct the converter to adjust the common mode voltage variably in accordance with changes in the modulation index and the modulation control factor. This disclosure enables the automatic adjustment of the common-mode-voltage according to the DC voltage and the AC voltages, based on pre-defined performance of the converter in terms of switching losses, CMV, and harmonics. With this automatic adaption, the modulation of the converter is changed between discontinuous mode to continuous mode.

Embodiments disclose methods for enabling an unequal modulation in a wireless local area network. The method determines a number of spatial streams (NSS) per UE associated with a user. The method determines a type of unequal modulation to be enabled at the UE. The method identifies a primary spatial stream, based on the type of unequal modulation to be enabled at the UE (102). The method enables assignment of the at least one unequal modulation index to all the spatial streams based on at least one of the NSS, the maximum difference in the modulation index allowed across different spatial streams per user, the type of unequal modulation to be enabled at the UE (102) and the identification of the primary spatial stream.

The present invention discloses a control method, device, three-level converter, storage medium, and processor for a three-level converter. The method includes: transforming the space vector of the three-level converter from a rectangular coordinate system to a 60° coordinate system; re-dividing the sectors of the space vector of the three-level converter under a virtual space vector modulation strategy in the 60° coordinate system; re-synthesizing the space vector of the three-level converter based on the re-divided sectors; calculating the action times of adjacent re-synthesized vectors; and allocating the vector action times of the three-level converter based on the calculated action times of adjacent vectors to control switches in the three-level converter and achieve midpoint potential balance control of the three-level converter. This solution, by re-dividing the sectors and re-synthesizing the vectors using the 60° coordinate system, achieves midpoint potential balance under high modulation index, which is beneficial for improving the output performance of the three-level converter.

The present invention provides a modulation index compensation method based on synchronous SVPWM, comprising: presetting a theoretical modulation index, and determining a sampling angle according to a frequency division number and a preset modulation strategy; calculating a comparison value at the sampling angle according to the theoretical modulation index; calculating a U-phase voltage pulse switching angle according to the comparison value; calculating an actual phase voltage fundamental peak value according to the U-phase voltage pulse switching angle; calculating an actual output line voltage effective value according to the actual phase voltage fundamental peak value; calculating an actual modulation index according to a ratio of the actual output line voltage effective value to a DC bus voltage; determining a formula for calculating the theoretical modulation index through the actual modulation index, obtaining a theoretical modulation index corresponding to each actual modulation index under each frequency division number, and storing a corresponding relationship between the actual modulation index and the theoretical modulation index when the frequency division number is greater than 3; in application, querying the corresponding relationship through the current demand modulation index to obtain the corresponding current theoretical modulation index, so as to compensate for the current demand modulation index.

The application belongs to the technical field of rectifiers, and proposes a sector division-based optimization control method and system for DC link current ripple in a three-phase current source rectifier, the main scheme of which is as follows: firstly, a dual-variable operating region judgment mechanism based on modulation index and sector angle is used to identify the operating region of the current three-phase current source rectifier; secondly, a corresponding modulation strategy is selected based on the operating region of the current three-phase current source rectifier, so that each modulation strategy operates in its optimal interval; finally, according to the selected modulation strategy, the action time of each reference vector is integrated to finally generate a drive signal sequence of the three-phase current source rectifier. The application can ensure the power quality output by the three-phase current source rectifier.

An electrified vehicle includes a motor having a plurality of windings, a first inverter, a main battery, and a controller configured to perform linearization control on a voltage modulation index, so as to limit a change rate of the voltage modulation index during switching between a first driving mode and a second driving mode while an auxiliary battery is mounted.

The present invention discloses a method, system and medium for estimating parameters of a sinusoidal frequency modulation signal. The method includes the following steps: obtaining a sinusoidal frequency modulation signal, calculating the instantaneous frequency after performing differential calculation on the sinusoidal frequency modulation signal, downsampling the instantaneous frequency according to a preset maximum number of periods, and then obtaining the spectrum of the downsampled instantaneous frequency; calculating the frequency estimation value f of the sinusoidal signal in the sinusoidal frequency modulation signal according to the maximum value in the spectrum me , calculating the period of the sinusoidal signal in the sinusoidal frequency modulation signal according to the frequency estimation value f me , calculating the weighted cumulative value y of the instantaneous phase according to the period of the sinusoidal signal, the instantaneous frequency and the frequency estimation value f me , calculating the modulation index estimation value m according to the weighted cumulative value y of the instantaneous phase f and the bandwidth estimation value Bw of the sinusoidal frequency modulation signal, and calculating the carrier frequency estimation value f0 of the sinusoidal frequency modulation signal according to the modulation index estimation value m f and the frequency estimation value f me . The algorithm logic of the present invention is simple and can better estimate various parameters of the sinusoidal frequency modulation signal.

The invention discloses a high-bit-rate multi-index continuous phase modulation signal receiver which comprises a frequency conversion and conditioning module, an AD daughter card module, a frequency synthesis module, an FPGA chip 1 and an FPGA chip 2. Wherein the frequency conversion and conditioning module is configured to complete down-conversion and AGC (Automatic Gain Control) of an S-band radio frequency signal and output an S-band intermediate frequency signal; the AD daughter card module is configured to convert a received S-band intermediate frequency signal into an intermediate frequency digital signal; the frequency synthesis module is configured to complete system work clock generation; the FPGA chip 1 is configured to complete Doppler frequency capture of a received intermediate frequency digital signal, send the captured signal to the FPGA chip 2, receive a demodulation information sequence fed back by the FPGA chip 2 to complete LDPC decoding, descrambling and frame synchronization of corresponding data, and output telemetry data; the FPGA chip 2 is configured to perform carrier phase tracking, modulation index synchronization, timing synchronization and sequence detection on received data.

This invention relates to a low-complexity demodulation method and system for multi-exponential CPFSK signals. The method includes the following steps: Based on the characteristics of multi-exponential CPFSK signals, data features are extracted by processing the signals, including in-phase I-path sampling, quadrature Q-path sampling, and first-order phase difference. A signal dataset is generated based on the data features, modulation index, and labels, and preprocessed. A demodulation model based on a convolutional neural network and a demodulation model based on convolution and attention mechanisms are designed, using data features and modulation index as inputs and the demodulation result as output. A loss function is constructed based on the error between the predicted demodulation result and the labels, and the demodulation model is trained. The trained demodulation model is tested and post-processed. Based on the post-processing result, one of the demodulation models is selected for demodulating the CPFSK signal. Compared with existing technologies, this invention has advantages such as reducing demodulation complexity and improving the real-time performance of the demodulation process.

A method includes voltage vector command values for an electric motor implemented on a vehicle and operating in a linear region. The method also includes receiving system state information of the vehicle and determining that an overmodulation threshold is satisfied based on the system state information of the vehicle. Based on determining that the overmodulation threshold is satisfied, the method includes determining a modulation factor from a modulation index, generating a three-phase output based on the voltage vector command values and the modulation factor, and determining a plurality of control signals based on the three-phase output. Each respective control signal of the plurality of control signals corresponds to a respective switch among a plurality of switches of an inverter. The method also includes instructing the plurality of switches of the inverter to control operation of the electric motor in the overmodulation region based on the plurality of control signals.

The present disclosure relates to a method, system, device and medium for hybrid modulation of a Doppler omnidirectional beacon signal, and relates to the field of antenna or signal and system technology. The method comprises: respectively configuring a first preset additional odd modulation function and a first preset additional even modulation function on one side of a preset odd mixing function and a preset even mixing function, to obtain a first upper sideband carrier signal and a first lower sideband carrier signal corresponding to the Doppler omnidirectional beacon; respectively configuring a second preset additional odd modulation function and a second preset additional even modulation function on the other side of the preset odd mixing function and the preset even mixing function, and respectively performing anti-phase modulation on the second preset additional odd modulation function and the second preset additional even modulation function according to a set modulation index, to obtain a second upper sideband carrier signal and a second lower sideband carrier signal corresponding to the Doppler omnidirectional beacon. The embodiment of the present disclosure can realize hybrid modulation of the Doppler omnidirectional beacon signal.

A method for motor control includes receiving a plurality of data points associated with operation of a motor, determining a phase angle of the motor, and obtaining a seven-phase pulse width modulation equation from a lookup table based on the phase angle of the motor. The method further includes determining a result of the seven-phase pulse width modulation equation, receiving a modulation index value, and selectively controlling the motor based on the result of the seven-phase pulse width modulation equation in response to the modulation index value being less than or equal to a first threshold value.

The present disclosure relates to adaptive DC bus voltage systems and methods using a fixed modulation index. One method includes setting a modulation index to a predetermined value for a motor. The method also includes calculating a bridge voltage for an output voltage command based on the predetermined value of the modulation index, and selectively controlling the motor based on the bridge voltage.

The invention discloses an improved variable virtual space vector modulation method for a three-level inverter, and relates to the technical field of inverter design. The expected voltage under the alpha-beta coordinate system input by the controller is converted into a 60-degree g-h coordinate system; six large sectors are divided according to the angle of the expected voltage, the large sectors are rotated to the position of 0-60 degrees, and space coordinates of all basic vectors under the neutral-point potential imbalance condition are given; selecting a k value to divide the large sector into five small sectors A1-A5, and obtaining space coordinates of each virtual vector; duty ratio calculation is carried out, and the duty ratio of the A5 small sector is calculated through an improved method; introducing a middle vector balance factor h, and calculating an h value to adjust a midpoint potential; and updating the duty ratio and outputting PWM. According to the invention, the balance speed of the neutral-point potential at a high modulation degree can be improved, output harmonics are reduced under the condition that the neutral-point potential is unbalanced, the quality of output electric energy is improved, and no fluctuation of the neutral-point potential is realized under a full power factor and a full modulation index.

The invention discloses a non-contact characterization method and measurement system for bolt cross-elastoplastic stage relaxation based on third-order perturbation sound modulation, a storage medium and a program product, and the method comprises the steps: sequentially applying low-frequency pumping signals with different amplitudes and high-frequency detection signals with a constant amplitude through an incremental pumping excitation strategy; third-order nonlinear vibration sound modulation response of the bolt connection structure is excited; collecting a vibration response signal of the bolt connection structure by using a non-contact laser vibration meter, performing spectral analysis, extracting amplitudes of a fundamental wave and a first-order sideband signal, calculating a nonlinear index beta, and analyzing the concave-convex characteristic of the beta along with the change of the pumping excitation voltage; distinguishing an elastic relaxation stage and an elastic-plastic relaxation stage of the bolt according to the concave-convex characteristics of the beta curve; a correction modulation index gamma is constructed based on changes of the beta curve under different excitation voltages, and monotonous quantitative characterization of the bolt pre-tightening force in the relaxation process from the elastic-plastic stage to the elastic stage is achieved. The method has the advantage that the continuous, monotonous and quantitative characterization of the whole process from elastoplasticity to elastic relaxation of the bolt is realized.

A load transfer method and system based on a transformerless multi-port power router includes the following steps: determining the fault location; if the fault location is in a higher-level line of a line connected to an MTUPFC, disconnecting the higher-level power grid and changing the control strategy of each MTUPFC port to constant AC voltage control; if the fault location is in a line connected to the MTUPFC, selecting one of the lines as a balancing line; determining whether the fault occurs on the balancing line; if not, changing the control strategy of the MTUPFC port connected to the faulty line to constant AC power control; if so, first disconnecting the faulty line; if the faulty line is a passive network, changing the control strategy of the MTUPFC port connected to the faulty line to constant AC voltage control; changing the control strategy of the port connected to the balancing line to optimal modulation index control; and if the faulty line is an active network, adjusting the control strategy of each MTUPFC port based on the power capacity of the active network. This invention can fully utilize the remaining capacity of other lines to maximize power restoration to the power-lost area.

The invention relates to an intelligent drill rod communication method, system and equipment based on VMSK, and a medium. The method comprises the following steps: carrying out VMSK modulation on input data according to a preset modulation index; after the VMSK modulation signal is converted into a magnetic signal at the sending end, the magnetic signal is sent to the receiving end through an intelligent drill rod channel, and the receiving end converts the received magnetic signal into an electric signal; and carrying out VMSK demodulation on the electric signal to obtain original input data. The input signal is modulated in a VMSK modulation mode, one-bit information is represented by one carrier period in combination with the channel characteristics of the intelligent drill rod, the digital communication frequency of 500 kHz is achieved, and the method can be widely applied to the field of intelligent drill rod communication.

The invention provides a multi-level power converter fault tolerance method, which comprises the following steps of: acquiring an output voltage, an inverter side current and a direct current side voltage, performing conversion, and performing PI modulation to obtain a modulation wave of a system; judging whether the system has a fault or not, and judging a specific fault-tolerant scheme according to the modulation degree of the modulation wave if the system has the fault; based on a fault-tolerant scheme, selecting an output state of a redundant vector of a non-fault phase; and based on the selected output state, generating a corresponding driving signal through carrier phase-shifting PWM (Pulse-Width Modulation). The multi-level hybrid topology can keep the same working state before and after the fault, the floating capacitor voltage and the direct current side capacitor voltage are stable, the fault response is rapid, the large-range fluctuation of the output voltage and the output current is avoided, the smooth switching of the working modes is ensured, and the fault tolerance of the system is improved.

The present invention discloses a modulation method, device, three-level inverter, and storage medium for a three-level inverter. The method includes: obtaining the DC bus voltage and three-phase voltage of the three-level inverter; determining the modulation index and reference vector of the three-level inverter according to the DC bus voltage and three-phase voltage of the three-level inverter; selecting small vectors, synthesizing a virtual middle vector, and designing a switching sequence according to the modulation index and reference vector; determining the duty ratio of each vector of the three-level inverter based on the virtual middle vector and the switching sequence according to the volt-second balance equation and the numerical approximation method; and controlling the three-level inverter according to the duty ratio of each vector of the three-level inverter. In this solution, by setting a virtual vector in the space vector diagram of the three-level inverter, the midpoint current generated by the comprehensive action of the virtual vector, small vectors, and middle vector is 0, suppressing the fluctuation of the midpoint voltage, improving the output waveform quality of the three-level inverter, and ensuring the power consumption safety of electrical equipment.

A phase modulation signal generating device for a fiber-optic gyroscope includes a sine wave generating part and a superimposing part. The sine wave generating part generates a fundamental sine wave of an odd-order frequency (v=(2n+1)Ve, where n=0, 1, 2, . . . ) of the eigenfrequency (Ve) of the fiber-optic coil and a higher-order sine wave of an odd-order harmonic frequency ((2m+1) v, where m=1, 2, 3, . . . ) of the odd-order frequency (v). The superimposing part superimposes the fundamental sine wave and higher-order sine wave generated by the sine wave generating part at a ratio using a modulation index optimized according to a noise target to be minimized and outputs the resultant signal as a phase modulation signal.