115results about How to "Improve output waveform" patented technology

A shift register invention includes a plurality of stages outputting a plurality of output signals, in sequence. Each of the stages includes a driving part and a discharging part. The driving part includes a driving transistor. The driving transistor has a control electrode, a first electrode, a second electrode and a channel layer. The control electrode receives one of a start signal or an output signal of a previous stage. The first electrode receives a clock signal. The second electrode outputs an output signal of a present stage. The channel layer has a different length from a channel layer of a driving transistor of the previous stage. The discharging part discharges the output signal of the present stage based on an output signal of a next stage, therefore improving the electrical characteristics of the shift register.

The invention discloses a displacement buffer which can reduce a frequency coupling effect and a displacement buffer unit; wherein every level of the displacement buffer unit comprises at least a lifting driving module, a lifting module, at least a pull-down module and a pull down driving module; wherein, before a first frequency signal waveform or a second frequency signal waveform used by the lifting module forms an ascending edge, the pull-down driving module opens the conduction of the pull-down module for a particular period according to a first periodic signal; and/or before the first frequency signal waveform or the second frequency signal waveform used by the lifting module forms an descending edge, the pull-down driving module closes the conduction of the pull-down module for a particular period according to a second periodic signal; therefore, when the coupling effect of the frequency signal appears at that time, the pull-down module has enough ability to resist so as to improve the output waveform of the displacement buffer unit.

The invention discloses a current limit control method and a current limit control device of a three-level inverter. The current limit control device comprises a current limit control unit, an auxiliary switching tube switch-on unit and a main switching tube switch-on unit. The current limit control method includes: S1, when currents outputted by a bridge leg are larger than or equal to a current limit threshold value, switching off two main switching tubes and then switching off two auxiliary switching tubes; S2, when the currents outputted by the bridge leg are decreased to be smaller than the current limit threshold value, enabling the two auxiliary switching tubes to act according to normal switching logic; S3, when the currents outputted by the bridge leg are decreased to be smaller than the current limit threshold value and effective edges of PWM (pulse-width modulation) signals of the main switching tubes or auxiliary switching tubes are reached, enabling the two main switching tubes to act according to the normal switching logic. By the current limit control method and the current limit control device, time for mutual energy infusion and mutual charging of positive and negative buses is shortened, overvoltage of the unilateral bus is avoided, frequent actions of the main switching tubes are avoided, the switching tubes are protected, and output voltage waveforms are improved.

The invention discloses a method for controlling the balance of capacitive voltages of a five-level diode neutral point clamped converter. The method has the advantages that an integral modulation degree area is divided into a low modulation degree area (with an m<SV> smaller than or equal to 0.5) and a high modulation degree area (with an m<SV> larger than 0.5), and direct-current-side voltages of different modulation degree areas are controlled by different processes; a process for optimizing objective functions and a process for decomposing a reference voltage are combined with each other in a process for controlling the direct-current capacitive voltages in the low modulation degree area, the process for controlling the direct-current capacitive voltages in the low modulation degree area can be implemented easily, redundant switch states of various vectors are sufficiently utilized, and waveforms outputted by a system are improved; and complicated overlap area judging algorithms are omitted in an optimized process for selecting balancing vectors in the high modulation degree area, and the system is high in the response speed.

The invention belongs to the technical field of power electrons and particularly relates to a modularized multi-level full-bridge resonant power electronic transformer topology. The topology specifically comprises high-voltage side three phases which are of three-phase star connection structures, each phase is of the same structure, and each phase comprises Nt subunits and Nt low-voltage side full-bridge modules; each subunit comprises a resonance LC and a high-frequency transformer, and a high-voltage side MMC full-bridge module of each phase is shown in the description; in every two adjacent subunits, each MMC module generates a part of the base frequency phase voltage output and produces a high-frequency square wave with equal production amplitude and opposite phases at the same time, the high-frequency square wave is filtered and passes through bridge arm resonance LC, and after being separated and reduced voltage by the high-frequency transformer, the high-frequency square wave is rectified by a low-voltage side H bridge module to a low-voltage direct current bus. Compared with the high-voltage side and intermediate topology of a traditional power electronic transformer, the high-frequency transformer number, module number, capacitance number and switch number can be saved, and the topology has a good output waveform at the same time.

An optical transmission module of the invention uses a semiconductor chip forming an optical modulator integrated laser on a semi-insulating semiconductor board. An input transfer line and an anode electrode of an optical modulator element are connected by a first bonding wire. The anode electrode of the optical modulator element and one of the ends of a terminal resistor element are connected by a second bonding wire. A cathode electrode of the optical modulator element and the other end of the terminal resistor element are connected by a third bonding wire. The cathode electrode of the optical modulator element and a ground electrode are connected by a fourth bonding wire. A joint portion between the first bonding wire and the input transfer line is arranged on an opposite side to a joint portion between the fourth bonding wire and the ground electrode while interposing the semiconductor chip between them.

The invention discloses a synchronous inverter control system suitable for a working condition of unbalanced power supply, comprising a power source, a three-phase inverter main circuit, an LC filter circuit and a power grid which are connected in sequence, and also comprising a current acquisition module, a voltage acquisition module, a voltage signal processing module, a power calculation module, a voltage reference signal amplitude calculation module, a voltage reference signal phase calculation module, a voltage reference signal generation module, a current loop reference signal generation module, a positive sequence modulating signal generation module and a modulation module. The synchronous inverter control system can realize the working of a synchronous inverter based on virtual synchronous machine control as core in the working condition of unbalanced power supply.

The invention provides a three-level active triple harmonic injection matrix converter with a T-shaped structure. The three-level active triple harmonic injection matrix converter comprises a rectification-stage circuit, a triple harmonic injection circuit, an inversion-stage circuit and an input LC filter, wherein the rectification-stage circuit is used for rectifying an alternating current input from a three-phase AC input voltage provided by a three-phase AC power supply to a six-pulse DC voltage, the triple harmonic injection circuit is used for generating triple harmonic from a direct current and injecting the triple harmonic to the rectification-stage circuit, the inversion-stage circuit is used for converting the direct current to the alternating current, and the input LC filter comprises a filtering inductor and a filtering capacitor and is used for filtering and providing a neutral point of an inversion stage in the inversion-stage circuit. The three-level active triple harmonic injection matrix converter has the advantages of better control performance, lower common-mode level and higher system efficiency, the control range of input reactive power is expanded, synchronous modulation is not needed, higher output power quality is also provided, and an output waveform is improved.

The invention discloses an orthogonal detector circuit based on DDS chip phase shift. The circuit comprises a phase shift circuit, a first phase-sensitive detector, a first low-pass filter, a second phase-sensitive detector and a second low-pass filter. The phase shift circuit outputs a first reference signal to the first phase-sensitive detector and outputs a second reference signal to the second phase-sensitive detector. The first phase-sensitive detector conducts frequency mixing on an input signal and the first reference signal, and outputs a first sum frequency signal and a first difference frequency signal to the first low-pass filter. The first low-pass filter filters out the first sum frequency signal and outputs the first difference frequency signal Q (t). The second phase-sensitive detector conducts frequency mixing on the input signal and the second reference signal, and outputs a second sum frequency signal and a second difference frequency signal to the second low-pass filter. The second low-phase filter filters out the second sum frequency signal and outputs the second difference frequency signal I (t). According to the orthogonal detector circuit based on the DDS chip phase shift, the amplitude and phase of the input signal with the phase change can be accurately measured without the need of keeping the phases of the input signal and the reference signals identical or to be zero. The orthogonal detector circuit is simple, stable, reliable and easy to operate.

This invention relates to three phase stabilizing regulator comprising microcomputer sampling controller, control circuit and three phase compensation transformer. The characters are: secondary winding of each phase of the transformer having only one coil, and series connected between power source and load; each primary winding having more than one coils and taps, each tap being connected to corresponding phase and zero line of input three phase power source by corresponding contactor of control circuit or contact of solid relay. The main control point is that: phase voltage and/or line voltage in regular or irregular order combination is imposed upon each coil of primary winding of compensationt ransformer, to achieve even compensation, lowering working current in primary winding of compensation transformer. Advantaegs are: simple structure, low cost, high stability precision.

The invention discloses an arc-free compensatory single phase voltage regulating and stabilizing device, including protection electric appliance, sample controller, control circuit and compensating circuit, and its characteristic: the control circuit includes several relays, the control coil of each relay is controlled by the sample controller and the corresponding contact of each relay controls the compensating circuit. The compensating circuit includes a compensating transformer, the secondary winding coil of the compensating transformer is connected in series between power supply and load and the primary winding coil is provided with several series coils, the tap terminal of each coil is connected with phase or zero lines through the corresponding contacts of several relays of the control circuit. In use course, the voltage and current is uninterrupted, the primary winding coil makes forward or backward compensation on the output of the secondary winding coil by making delayed and arc-free switching of different coil groups under the control of the sample controller and control circuit, realizing the function of adjusting and stabilizing output voltage. It is applied to single phase voltage adjusting and stabilizing power supply.

The invention relates to a frequency converter, in particular to a high-voltage matrix converter. At present, frequency converters are high in cost, large in size, short in service life, high in output voltage harmonics and low in power factor. The high-voltage matrix converter comprises a phase shift isolation transformer, a matrix transformation unit array and a general controller, wherein the phase shift isolation transformer is provided with 3n three-phase secondary windings, and the matrix transformation array is of array structure formed by arranging 3n matrix transformation units in a mode that 3 rows time n lines. In the matrix transformation unit array, power output ends of the matrix transformation units of each row are serially connected, each matrix transformation unit is composed of an input filter, a power switch array and sub-controllers. Power wires of the sub-controllers are connected with any two or three phases in input ends of preceding-stage three-phase bridge rectifying circuits in the power switch arrays, and signal wires of the sub-controllers are connected with the power switch arrays. The high-voltage matrix converter is low in cost, small in size, long in service life and easy to realize energy feedback, and the frequency converters are safe and stable in operation and low in cost.

The invention discloses a control method for canceling specified harmonics of a three-level midpoint clamp photovoltaic inverter. The control method comprises the following steps of: firstly, establishing a mathematical model of the control method for the specified harmonics of the three-level midpoint clamp photovoltaic inverter and solving the following nonlinear transcendental equations; secondly, establishing a midpoint current mathematical model of the three-level midpoint clamp photovoltaic inverter; and thirdly, solving by adopting a continuous space ant colony algorithm. According to the control method disclosed by the invention, the control method for canceling the specified harmonics of the three-level midpoint clamp photovoltaic inverter is combined with midpoint voltage balance; the midpoint voltage balance can be effectively controlled while the specified low-order harmonics are canceled, so that an output waveform is greatly improved and the total harmonic distorsion is reduced.

A multifunctional electric energy converter is composed of rectifier, filter, inverter, the differential mode voltage suppressing reactors serially connected to the outputs U, V and W of inverter, and filter capacitor group. Its features are that the output lines V, V and W of inverter are wound on a magnetic ring for isolating HF signals, decreasing output of common-mode voltage and improving output voltage waveform.

A display device includes a driving circuit that applies an active potential which is a potential for turning on pixel transistors sequentially to a plurality of output signal lines, wherein the driving circuit includes a main driving circuit that outputs the active potential to one end of the output signal line of the plurality of output signal lines by applying a clock signal caused by a input of the active potential output from the upper output signal line, and an auxiliary driving circuit that has an auxiliary transistor which is a transistor where the other end of the output signal line is connected to a signal line for the clock signal via the source or the drain. Thereby, output waveform distortion in the scanning signal line can be improved and thus display quality can be enhanced.

The invention relates to a feedforward control method for an intermediate-frequency lower twin-stage matrix converter, comprising the following steps: sampling the three-phase input voltage of a twin-stage matrix converter by a sampling circuit, calculating out a rectifier-stage switch duty ratio 1 by a common-mode error elimination method, looking up a table to obtain a three-phase input voltage phase 1 before calibration, carrying out feedforward calibration to obtain a three-phase input voltage phase 2 after calibration, and looking up the table to obtain a rectifier-stage switch duty ratio 2 after calibration; carrying out feedforward calibration according to the three-phase input voltage phase 2 after calibration to obtain a contravariant-stage primary three-phase input voltage corrected phase 3 after calibration and a contravariant-stage secondary three-phase input voltage corrected phase 4 after calibration, looking up the table to obtain a contravariant-stage primary correction factor 1 and a contravariant-stage secondary correction factor 2, and calculating out a contravariant-stage switch duty ratio; and controlling the 18 power switches of the twin-stage matrix converter according to the rectifier-stage switch duty ratio 2 and the contravariant-stage switch duty ratio.

An optical transmission system includes an optical nonlinear element having nonlinear input/output characteristics, a power detector detecting a power of a specific frequency component related to an optical signal reproduced by the optical nonlinear element, and a variable amplifier amplifying or attenuating the optical signal inputted to the optical nonlinear element. Evaluation of an output waveform is performed based on the power of the specific frequency component detected by the power detector, and a gain of the variable amplifier is properly controlled, so that an input power of the optical signal inputted to the optical nonlinear element can be easily set such that a good output waveform can be obtained without directly measuring the inputted or outputted optical signal.

An encoder signal compensation method and the apparatus thereof are described. The encoder signal compensation method includes the following steps. First, encoder output signals are read to calculate compensation parameters. Subsequent encoder output signals are compensated according to the calculated compensation parameters and the compensated encoder output signals are utilized to control a printing process. The encoder signal compensation method is effective in eliminating width errors and phase errors of the encoder output signals. Another embodiment of the invention is to provide a printing apparatus utilizing the encoder signal compensation method to reduce high frequency banding, effectively improving the printing quality.

The invention relates to a complete-period selective harmonic elimination pulse width modulation method without waveform symmetry characteristics. The method includes the following steps: generating an ideal inverter output waveform, carrying out Fourier analysis on the ideal inverter output waveform, and determining a DC component and a Fourier coefficient of the ideal waveform; making fundamental waves of a bipolarity SHEPWM wave and the ideal inverter output waveform be equal to the Fourier coefficients and the DC components of controlled harmonics to obtain a nonlinear equation set, and carrying out solution by using the nonlinear equation set to obtain a group of switch angles; and controlling the on-off of an inverter power device by the obtained switch angles so as to realize accurate control of the DC component and the fundamental wave of an inverter output signal, and the amplitudes and the phases of the controlled harmonics. According to the method provided by the invention, the 1/2 period or 1/4 period cycle symmetry constraints of the inverter voltage output waveform, the DC component and the fundamental wave of the inverter output waveform and the amplitudes and the phases of the controlled harmonics are accurately controlled to obtain waveforms meeting the requirements of output components.

The invention discloses a pulse-width modulation (PWM) inverted power supply system and a PWM inverted power supply algorithm based on a fuzzy predictive control technology. The input is direct current (DC) voltage, and the input passes through a DC booster circuit, is subjected to ripple wave removal through a filtering circuit and passes through a DC/alternating current (AC) inversion circuit; the output is high-voltage AC, an AC voltage detection feedback circuit, an overcurrent detection feedback circuit, a DC detection feedback circuit, a DC voltage detection feedback circuit and other protection circuits are arranged in the circuit, when overcurrent and overvoltage are detected, a control chip obtains a reasonable dead-zone predictive control scheme through an algorithm according to data which is acquired in real time, the PWM driving pulse waveform is changed, and the working reliability of a switching device is effectively guaranteed; meanwhile, the conversion efficiency of a PWM inverter system is high, and the distortion rate of output waveform is reduced. The invention is applicable to fields of switching power supply inverters, solar inverted power supplies, small wind driven generator inverted power supplies and the like.

The invention relates to a seven-level circuit, a grid-connected inverter and a modulation method and device of the seven-level circuit. The seven-level circuit comprises a DC boosted circuit and a symmetric dual-Buck circuit; the DC boosted circuit comprises a DC chopper and a fourth capacitor which are connected in series; an eighth switching tube is connected between the common terminal of the DC chopper and the fourth capacitor and the common terminal of a first switching tube and a first diode; the symmetric dual-Buck circuit comprises the following structures that a first capacitor and a second capacitor are connected in series and then connected to two sides of a DC power supply in parallel, the first diode and a second diode are connected in series and then connected with the DC power supply in parallel, the first switching tube is arranged between the first capacitor and the second diode, and a second switching tube is arranged between the second diode and the second capacitor; a first inductor is arranged between the first diode and the output end of the seven-level circuit, and a second inductor is arranged between the common terminal of the second switching tube and the second diode and the output end of the seven-level circuit; and a common point of the first capacitor and the second capacitor is connected with a common point of the first diode and the second diode. The seven-level circuit, the grid-connected inverter and a control method and device of the grid-connected inverter give consideration to two aspects of current and high efficiency.