227results about How to "Improve waveform quality" patented technology

The railway system has a DC voltage catenary (20) connected to a rectifier bridge block (40) that is in turn connected to a transformer (30) joined to a three-phase AC grid (10). The device (50) has a first DC/DC voltage raising block (51) connected between the catenary (20) and an intermediate bus that is connected to a second DC/AC three-phase current generation block (52) joined to the transformer (30). The first block (51) allows raising the DC voltage of the catenary (20) generating a controlled voltage with which the second block (52) generates a high-quality three-phase current that is delivered to the grid (10).

A control method and apparatus are provided to convert a DC voltage into alternating voltage. The apparatus includes a first inverter and a second inverter to generate a first alternating voltage and a second alternating voltage, respectively. Also included is an interphase transformer to combine these alternating voltages in parallel to obtain a first resulting alternating voltage. The apparatus also includes a third inverter and a fourth inverter to generate a third and fourth alternating voltage, respectively. These are combined to form a second resulting alternating voltage. The second resulting alternating voltage is displaced in phase approximately 180° in relation to the first resulting alternating voltage.

The invention relates to a standard Z source three-level T-shaped inverter and an SVPWM method thereof. A topology has boost features identical to boost features of a standard Z source network three-level NPC inverter, however, few switching elements are utilized, and efficiency is high. Compared with a three-level T-shaped inverter, functions of boost and voltage reduction of the topology can be achieved, direct connection of an upper bridge arm and a lower bridge arm is allowed, reliability is improved remarkably, dead time is eliminated, and waveform distortion is prevented. Compared with a Z source three-level diode clamped inverter, current at an input end is continuous, ripple waves are small, and the input end does not need to be connected with a large-capacitance array set in parallel. Compared with a standard Z source two-level inverter, output voltage has neutral point electric potentials, therefore, high frequency harmonic waves are small, a required filter is small, a switching frequency can be reduced, and switching loss is less. The SVPWM method is adopted to control the inverter, so that switching frequencies are decreased, switching loss is reduced, and harmonic contents of the output voltage are reduced.

The invention discloses an in-phase laminated carrier wave modulation method for a multi-module matrix converter. The method is characterized in that the modulated wave of each module is determined according to the range where a system modulated wave is in; and a carrier wave modulation method of a double-side-symmetric non-isoceles triangle carrier wave-type is adopted for each module. The modulation idea comes from that functions of a three-module matrix converter includes that of a full bridge indirect matrix converter, a modulation algorithm of the full bridge indirect matrix converter is combined, the space vector modulation is adopted for the rectification grade, the in-phase laminated carrier wave modulation is adopted for the inversion grade, and the state of each switch of the three-module matrix converter is determined through the corresponding relation of mathematical models of the three-module matrix converter and the full bridge indirect matrix converter. The modulation method provided by the invention is low in computational complexity and easy to expand; the switch change-over frequency is greatly lowered, the system efficiency is improved; the output voltage level can be smoothly switched; and the output current waveform quality is good.

The invention discloses an optimized-levenberg-marquardt (LM)-algorithm-based laser radar waveform decomposition method. The method comprises the following steps that: (1), a laser radar system records observation waveform data of back scattering in a digital mode; (2), signal enhancement is carried out on the observation waveform data, wherein the signal enhancement contains noise processing and smoothing processing; (3), a threshold value is set, peak-inflection point detection is carried out on the enhanced signal, and initialization estimation values containing a number, an amplitude, a position, and a pulse width initialization parameter are determined; (4), a standard LM algorithm is corrected by using an improved training module and iteration is carried out on the initialization estimation values to obtain feature parameters, including amplitudes, positions, and pulse widths, of all components of the enhanced signal; and (5), goodness of fit is calculated by using fitting data and original observation data and precision of the goodness of fit is determined; and an efficiency of a fitting algorithm is determined by using the number of times of iteration.

The invention discloses a middle point voltage control device and method based on modulation wave interval division. The device comprises a three-level inverter, a digital processing control module and a driving circuit, wherein the digital processing control module comprises a sampling unit, a closed-loop control unit, a sine pulse width modulation unit, a modulation wave interval division unit and a zero-sequence component calculation unit. The method comprises steps that an offset angle of a zero-crossing point after adding a zero-sequence component to a three-phase modulation signal is calculated; the modulation wave interval is divided, and the zero-sequence component required to suppress the midpoint voltage fluctuation is calculated; the sign of the zero sequence component is determined through comparing instantaneous voltages of upper and lower capacitors of the DC side; the zero-sequence component is added to the three-phase modulation signal and is then processed by the sinepulse width modulation unit to acquire a pulse width modulation control signal, and a switch tube of the three-level inverter is controlled by the driving circuit for operation. The device is advantaged in that hardware cost is low, accurate control is realized, the application scope is wide, the midpoint voltage fluctuation can be effectively inhibited, and the distortion rate of the network current is reduced.

The invention discloses a quenching reset circuit for a single photon avalanche diode detector. The reset circuit comprises three parts such as a quenching circuit, a reset circuit and an avalanche signal output portion, and is characterized in that the quenching circuit is composed of five MOS transistors, and the five MOS transistors form a positive feedback circuit for voltage variations of a node a; the reset circuit is composed of 17 MOS transistors; and the avalanche signal output portion is composed of eight MOS transistors. The advantages are that the quenching reset circuit is high in reliability, and a reset operation is ensured to be performed after avalanche current generated by the SPAD (Single Photon Avalanche Diode) detector is sufficiently quenched because of adoption of a Schmitt trigger with high threshold level. In addition, the waveform quality of avalanche pulses generated by the circuit is high, avalanche signals are converted into narrow pulses through a NOR gate, and then the narrow pulses are shaped by a two-stage inverter and act as final output avalanche pulses, so that the output pulses are enabled to be steeper, and processing of a counting circuit is facilitated.

The invention relates to a low-torque fluctuation built-in permanent magnet motor rotor and a method for optimizing the magnetic density of the motor, belonging to the technical field of permanent magnet motors. The technical solution is: the permanent magnet under one magnetic pole is composed of two inline permanent magnets (3) and one V-shaped permanent magnet (2), one V-shaped permanent magnet (2) is located in the middle, and two inline permanent magnets (2) The permanent magnets (3) are respectively located on both sides of the V-shaped permanent magnet, forming an M-shaped magnetic circuit structure as a whole; 2p M-shaped magnetic steel slots (4) are evenly distributed in a ring on the entire rotor core (1), where p For the number of pole pairs of the permanent magnet motor, two inline permanent magnets (3) and one V-shaped permanent magnet are arranged in the M-shaped magnetic steel groove. The invention adopts a uniform air gap, which does not increase the difficulty of manufacturing the motor, nor changes the manufacturing process of the motor, effectively reduces the harmonic content in the air gap magnetic field, reduces the harmonic loss of the motor, improves the efficiency of the motor, and reduces the Cogging torque, reducing vibration and noise of permanent magnet motors.

The invention discloses a three-level NPC inverter neutral point potential equalization control method based on neutral point current. Upper and lower capacitor voltage and neutral point current are sampled in real time, the upper capacitor voltage and the lower capacitor voltage are compared to obtain a capacitor voltage difference value, voltage equalizing regulating quantities are obtained according to the capacitor voltage difference value, neutral point current polarity and three-phase original modulating wave polarity to regulate the three-phase modulating waves v<ma>, v<mb> and v<mc>, thereby obtaining three-phase modulating waves v<ma'>, v<mb'> and v<mc'>, the three-phase modulating waves are compared with triangular carriers C<up> and C<down>, and a PWM signal is output to control the on-off state of an inverter switching tube, thereby realizing regulation of neutral point potential. In the method provided by the invention, since pulsation frequency of the voltage equalizing quantities is larger than carrier frequency, the method for regulating the neutral point potential has a high frequency characteristic, can realize regulation of the neutral point potential in an NPC inverter in a very short time, and is good in real-time performance and high in control precision.

The invention belongs to the technical field of electric power and electronic engineering and specifically relates to a control system and a control method of a three-phase three-level VIENNA rectifier. The provided control system and control method of a three-phase three-level VIENNA rectifier is aimed at solving the problem that the input current of three-phase PFC converter will produce large third harmonic component under the traditional one-cycle control theory. To solve the above technical problem, the invention provides the control system and control method of a three-phase three-levelVIENNA rectifier; the system attenuates the second harmonic component contained in the output signal of the voltage regulator and does not affect signals in other frequency bands. The invention effectively suppresses the large amplitude three-phase harmonic component of the three-phase input current and improves the quality of the rectifier input current waveform.

The invention discloses an integrated static compensator of a distribution transformer, comprising the distribution transformer, a static compensation module and a control platform, wherein each phase winding at a high-pressure side of the distribution transformer is provided with a connecting tap; the connecting tap is connected with an alternating current output side of the static compensation module; and the control platform controls the static compensation module to inject reactive power by the connecting tap so as to realize compensation. The integrated static compensator centralizes to compensate at a key node, thus improving the capacity of the static compensator of existing distribution networks and improving the quality of compensated output waveform.

An image display apparatus includes a timing controller to generate a control signal according to image data, a driver IC to take in image data according to the control signal and to supply the image data to source lines, and a display panel to perform screen-displaying according to the image data supplied to the source lines. Plural input ports of the driver IC, from which the image data are inputted, are arranged asymmetrically with respect to an input port for the control signal. The timing controller includes plural data output ports to output image data to the driver IC, an arrangement information storing unit to store arrangement information defining normal and reverse orders of arrangement of the image data, and an output port switching unit to determine an order of arrangement of the image data according to the arrangement information and to supply the image data.

The invention discloses a multi-parameter collision waveform quality evaluation method and aims to solve the problems of time and money consuming during judgment of collision waveform quality and relatively strong randomness of an evaluation result in the prior art. The method comprises the steps that 1) a detailed waveform processing module obtains detailed waveform parameters through a detailed collision waveform of a vehicle body: (1) the detailed waveform processing module obtains a speed-time curve; (2) the detailed waveform processing module obtains a displacement-time curve; and (3) empirical parameters are extracted from the detailed waveform; 2) an equivalent dual-step waveform simplification module simplifies the detailed collision waveform of the vehicle body and obtains feature parameters; 3) a multi-parameter collision waveform evaluation criterion diagram is established; and 4) a signal output module gives out the evaluation result, namely, a central processing module (2) stores collision waveform feature parameter values obtained by a signal processing module (1) into the multi-parameter collision waveform evaluation criterion diagram and outputs the criterion diagram with the collision waveform parameter values to the signal output module (3), so that the evaluation result is obtained.

The invention discloses a diode clamping three-level frequency converter, and relates to the field of intermediate pressure motor control. A 12-pulse rectifying link is mainly formed by a phase-shifting transformer and a diode full-bridge rectifying unit, an inversion unit consists of an insulated gate bipolar transistor (IGBT) and a fast recovery diode which are packaged in a module, and a main inversion circuit of the diode clamping three-level frequency converter consists of two power modules formed by serially connecting an anode with an IGBT collector and parallelly connecting an IGBT emitter with a cathode. The diode clamping three-level frequency inverter has the advantages that: the IGBT and the fast recovery diode for clamping have matched voltage current characteristics; meanwhile, the change of a distribution parameter caused by external wiring is reduced, the switching loss of a switching tube is reduced, and the quality of an output waveform and the efficiency of the whole frequency converter are improved.

The invention provides a dynamic voltage correcting device. The dynamic voltage correcting device comprises a first convertor composed of L, S5, S6, C1 and C2, a second convertor composed of D1, D2, S1, S2, S3 and S4, an LC filter composed of Lf and Cf and a bilateral switch. A terminal a and a terminal b are alternating current input ends, and are connected with an alternating current power source. A terminal c and a terminal d are alternating current output ends, and are connected with an alternating current load. When the amplitude of the voltage of the alternating current power source falls below or rises above the normal range, the bilateral switch is cut off. According to the dynamic voltage correcting device, the voltage of the alternating current input ends and the output voltage of the second convertor are filtered by the LC filter after superposition is conducted on the voltage of the alternating current input ends and the output voltage of the second convertor, so that the voltage amplitude of alternating current output ends is corrected to the normal range. When short-circuit malfunction occurs in the load, a load short circuit current is limited by the device, so that the alternating current power source is free from the effect of the load short circuit. Due to the fact that the dynamic voltage correcting device is not provided with a transformer and an external power supply, the dynamic voltage correcting device has the advantages of being small in volume, light in weight, simple in structure and high in output waveform quality.

An active/passive switching control method for an MMC-HVDC island power grid is a control method capable of enabling an island power grid to realize smooth and stable switching at active/passive switching moments. The method includes the following steps of: firstly, when an island power grid is in an active network state, judging whether a power generation system is normally operated, and if the power generation system is normally operated, determining that the island power grid continues to operate in the active network state; if the power generation system exits the operation in the event ofa fault, determining that the island power grid generates active power vacancy and results in power grid frequency oscillations, dynamic load changes and other phenomena, wherein at this time, a phase angle following and outer loop power optimization control method needs to be added at the switching moment, so that the fluctuation of each electrical quantity at the switching moment is minimized,and the system gradually returns to a stable state; and finally, smoothly switching the island power grid to a passive network state. By adopting the method, the reliability of the island power grid at the switching moments can be improved, the normal operation of the island power grid at both the active and passive states can also be ensured, and the stability of the system can be enhanced.

Techniques are disclosed for selecting transmission resources in a telecommunications system that comprises different networks, where the techniques are based on the quality of the waveform of transmitted media such as audio or video signals, in contrast to the quality of service of the network that transports the media. The problem with only using quality of service to determine which resources to allocate to a call is that quality of service does not guarantee that the quality experienced by the call's participants is satisfactory just because a component network's quality of service is satisfactory. For example, the end-to-end delay experienced in a VoIP network might be satisfactory for most data transfers, but might still be inadequate to control the echo experienced by telecommunications users. The disclosed techniques evaluate the waveform quality (i.e., in terms of loudness, noise, echo, and so forth) of media that is transmitted along a path and allocate alternative resources accordingly.