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

The disclosed modulation technology for three-level high-voltage frequency converter comprises: to three-level NPC frequency converter, using asynchronous SVPWM when frequency less than 45Hz, and obtaining switch frequency as 600Hz; using special eliminating-harmonic PWM when frequency over 45Hz, and obtaining the switch number is seven. This invention avoids defects of space-vector PWM and special eliminating-harmonic PWM, improves waveform quality, reduces heat loss and request on filter, and ensures system security and reliability.

The invention relates to a portable high-voltage nanosecond squarer which belongs to a medicinal device for inducing cancer cell apoptosis by using a high-voltage nanosecond square wave pulse electric field. The portable high-voltage nanosecond squarer mainly comprises a power supply system, a high-voltage direct current module, a low-voltage power supply, a pulse forming system and a pulse shaping and counting system. The portable high-voltage nanosecond squarer has output pulses with highest amplitude of 15kV, pulse width adjustment range of 50ns-1us, rising edge gradient of reaching 10ns and controllable recurrence frequency of 0.2-15Hz; and the quantity of the output pulses of the portable high-voltage nanosecond squarer can be set. The portable high-voltage nanosecond squarer can be adjusted in multiple-parameters (pulse amplitude, pulse width, recurrence frequency, pulse quantity and the like), large-range and flexible and independent way, and is beneficial to researching the optimal window parameter of the cancer cell apoptosis and promoting the cancer cell apoptosis as well as improving the cancer treatment effect. Meanwhile, the portable high-voltage nanosecond squarer has compact and light structure, reliable work, simple operation and convenient popularization and application, and can be widely applied to the treatment of various cancers.

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 discloses a method for controlling a three-phase LCL (Lower Control Limit) type grid-connected inverter, comprising the steps of: (1) detecting a capacitor current iCx and a grid-connected current iL2x by respectively utilizing a current sensor Hi1 of the capacitor current and a current sensor Hi2 of filter inductance, carrying out collection and coordinate transformation to obtain a capacitor current feedback signal iC-of-m and a grid-connected current feedback signal iL2-of-m, detecting a grid voltage vgx by utilizing a voltage sensor Hv2 of the grid voltage, carrying out collection and coordinate transformation, and computing to obtain a grid voltage feed-forward signal vg-fd-m via a grid voltage feed-forward function Gg-fd; (2) computing to obtain an error signal e1m according to the iL2-of-m and iref-m; (3) carrying out closed-loop processing on the e1m by a controller to obtain a reference signal iC-ref-m of the capacitor current feedback signal iC-of-m, wherein the error signal e2m is equal to (iC-ref-m)+(vg-fd-m)-(iC-of-m); and (4) generating a PWM (Pulse Width Modulation) control signal for controlling a switching tube of an inverter bridge by utilizing the e2m. Through the method, the influence of the grid voltage on the grid-connected current waveform quality can be effectively suppressed, the network-access power factors are improved, the grid-connected current waveform quality is good and balanced current can be still injected into the grid by the inverter when the voltage of the three-phase grid is imbalanced.

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.

Provided are an optical transmitter device and an optical transmitter module which are capable of reducing the optical transmitter module size while maintaining a state where an excellent optical transmission waveform quality is obtained over a wide range of frequencies. The optical transmission module (2) includes a semiconductor laser diode device (10), an optical modulator device (12), and a first termination resistor circuit (14-1). A printed circuit board (4) includes a driver IC (16) and a second termination resistor circuit (14-2). A lower cutoff frequency of the first termination resistor circuit (14-1) and an upper cutoff frequency of the second termination resistor circuit (14-2) correspond to each other. An impedance of the first termination resistor circuit (14-1) in a pass frequency band thereof and an impedance of the second termination resistor circuit (14-2) in a pass frequency band thereof correspond to each other.

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.

Apparatus and method for generating high quality synthesized speech having smooth waveform concatenation. The apparatus includes a pitch frequency calculation section, a pitch synchronization position calculation section, a unit waveform storage, a unit waveform selection section, a unit waveform generation section, and a waveform synthesis section. The unit waveform generation section includes a conversion ratio calculation section, a sampling rate conversion section, and a unit waveform re-selection section. The conversion ratio calculation section calculates a sampling rate conversion ratio from the pitch information and the position of pitch synchronization, and the sampling rate conversion section converts the sampling rate of the unit waveform, delivered as input, based on the sampling rate conversion ratio. The unit waveform re-selection section selects, from the sampling-rate-converted unit waveform, the unit waveform having a phase necessary to obtain a synthesized speech waveform which will exhibit smooth waveform concatenation.

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 relates to a pendulum bob-type impact response spectrum testing bed which comprises a base, a guide rail, a sliding block and a bed face. A front waveform generator is fixed at one edge of the bed face, a back waveform generator is arranged on the base, the pendulum bob-type impact response spectrum testing bed further comprises a reducer fixedly connected with a left support, a motor connected with the reducer, a small gear connected with the reducer, a clutch and a pendulum bob rotation shaft, a big gear of the clutch is meshed with the small gear, the big gear of the clutch is fixedly connected with the pendulum bob rotation shaft, a friction hub of the clutch is fixedly connected with the pendulum bob rotation shaft, and the pendulum bob rotation shaft is supported by bearings fixed on the left support and a right support. The pendulum bob-type impact response spectrum testing bed further comprises an oscillating bar fixed on the pendulum bob rotation shaft and a pendulum bob fixed on the oscillating bar. The pendulum bob-type impact response spectrum testing bed achieves stable and rapid promotion of the pendulum bob and improves testing efficiency. The pendulum bob-type impact response spectrum testing bed enables the pendulum bob to slowly stop to achieve secondary impact resistance through friction plates and the friction hub. The pendulum bob-type impact response spectrum testing bed achieves bed face restoration, improves waveform quality and guarantees waveform consistency.

The invention relates to the technical field of photovoltaic grid-connected inverters. A photovoltaic inverter employing a hybrid type power device comprises two parts, namely, a power inversion unit and an inversion control unit, wherein the power inversion unit mainly comprises an input EMI (Electro-Magnetic Interference) filter circuit, an interleaving Boost boosted circuit, a full bridge inversion circuit employing a mixer and an output grid-connected filter circuit; the inversion control unit mainly comprises a power grid phase detection circuit, a sampling circuit and a controller. The photovoltaic inverter adopts a double-stage structure, and the first stage adopts interleaving Boost boosted voltage, so that the fluctuation of current is reduced, and output voltage ripple is reduced; the later stage inversion unit adopts a hybrid power device, so that the inversion consumption is effectively reduced, and the system efficiency is improved. The photovoltaic inverter has the characteristics of simple structure, easiness in circuit control and convenience in capacity expansion.

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 ripple built-in permanent magnet motor rotor and a method for optimizing the magnetic flux density of a motor, belonging to the technical field of permanent magnet motors. A permanent magnet under a magnetic pole consists of two line-shaped permanent magnets (3) and one V-shaped permanent magnet (2), the V-shaped permanent magnet (2) is in the middle, and the two line-shaped permanent magnets (3) are arranged at the two sides of the V-shaped permanent magnet to form an M-shaped magnetic circuit structure integrally. 2p M-shaped magnetic steel grooves (4) are uniformly distributed on the whole rotor iron core (1) in a circle, wherein p refers to permanent magnet motor pole pair, and the two line-shaped permanent magnets (3) and the V-shaped permanent magnet (2) are arranged in the M-shaped magnetic steel grooves. By means of the uniform air gap, the manufacturing difficulty of the motor is not increased, the manufacturing technology of the motor is not changed, the harmonic content in the air gap magnetic field can be effectively reduced, the motor harmonic loss can be reduced, the motor efficiency is improved, the motor gullet torque is reduced, and the vibration and noise of the permanent magnet motor is reduced.

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.

A multi-stage quick charging system is proposed. The system uses an intermediate power battery as voltage supporting point so that a converter having a fraction of the output voltage may control the entire power flow towards or from the battery of a vehicle or an electrical power device. The intermediate battery comprises several stages in series, associated with respective small chargers allowing a management of the charge balancing of the stages of the intermediate battery, since the chargers may be controlled in order to separately vary the contribution of each stage.

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.

The invention discloses a double-decompression grid-connected inverter which belongs to inverters. The double-decompression grid-connected inverter comprises a power network, a power supply, a first filter inductance, a first power switch tube, a first fly-wheel diode, a second filter inductance, a second power switch tube, a second fly-wheel diode, a third filter inductance, a third power switch tube, a fourth filter inductance and a fourth power switch tube. The double-decompression grid-connected inverter improves the reliability of the system, the fly-wheel diode can be designed to the optimum, each power switch tube does not need to set the dead zone time, the grid current waveform quality is improved, and compared with a double-decompression type half-bridge inverter, the availability ratio of input direct current bus voltage can be improved.

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 provides an intelligent wave generating water channel with an active feedback wave elimination function. The intelligent wave generating water channel comprises a wave generating deviceand a wave elimination device. The wave generating device comprises an active wave generating control system, a crank connecting rod mechanism and a wave generating swing plate. The active wave generating control system is connected with the crank connecting rod mechanism through a wave generating servo motor. The crank connecting rod mechanism is connected with the wave generating swing plate. The wave elimination device comprises an active wave elimination control system, a lead screw mechanism and a wave elimination swing plate. The active wave elimination control system is connected with the lead screw mechanism through a wave elimination servo motor, and the lead screw mechanism is connected with the wave elimination swing plate. The intelligent wave generating water channel further comprises an active wave generating measuring instrument and an active wave elimination measuring instrument which are arranged in the water channel and connected with the active wave generating control system and the active wave elimination control system correspondingly. The intelligent wave generating water channel is small in structure size, high in operability, high in wave quality, good in stability, easy to control and the like and has extremely-high application value and popularization value.

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 discloses a non-isolated photovoltaic grid-connected inverter and a control method thereof and belongs to the technical field of power electronics converters. The inverter comprises a power supply circuit (10), a high-frequency chopper circuit (20) and a low frequency inverter circuit (30), wherein the power supply circuit (10) is formed by a photovoltaic array and an input filter capacitor, the high-frequency chopper circuit (20) is formed by a first to a second power switch tube, a first diode and a first to a second filter inductor, the low frequency inverter circuit comprises a third, a fourth, a fifth and a sixth power switch tube, the first power switch tube and the second power switch tube are high frequency switches, and the third power switch tube, the fourth power switch tube, the fifth power switch tube and the sixth power switch tube are low frequency switches. The non-isolated photovoltaic grid-connected inverter and the control method thereof have the advantages that leakage current of the grid-connected inverter can be eliminated, grid-connected current waveforms qualities are improved, simultaneously the efficiency is high, the controlling is simple, the reliability is high and the like.

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.

Provided are an optical transmitter device and an optical transmitter module which are capable of reducing the optical transmitter module size while maintaining a state where an excellent optical transmission waveform quality is obtained over a wide range of frequencies. The optical transmission module (2) includes a semiconductor laser diode device (10), an optical modulator device (12), and a first termination resistor circuit (14-1). A printed circuit board (4) includes a driver IC (16) and a second termination resistor circuit (14-2). A lower cutoff frequency of the first termination resistor circuit (14-1) and an upper cutoff frequency of the second termination resistor circuit (14-2) correspond to each other. An impedance of the first termination resistor circuit (14-1) in a pass frequency band thereof and an impedance of the second termination resistor circuit (14-2) in a pass frequency band thereof correspond to each other.

A bidirectional transmission convertor suitable for a high voltage and a high power, comprising a power module. The power module comprises a high-frequency transformer and modules of a full-bridge topological structure which are respectively connected to each phase of the primary side and the secondary side of the high-frequency transformer, wherein the modules of the full-bridge topological structure which are respectively connected to each phase of the primary side and the secondary side respectively comprise four modules SMp and four modules SMs, each bridge arm of the modules of the full-bridge topological structure which are connected to each phase of the primary side is respectively provided with one module SMp, and each bridge arm of the modules of the full-bridge topological structure which are connected to each phase of the secondary side is respectively provided with one module SMs. The convertor reduces the switching frequency and the switching loss of a power tube, reduces the electrical stress borne by a single tube, and improves the waveform quality of an alternating current link.

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.