202 results about "Modulation factor" patented technology

A control device has a unit for preparing a pattern having first and second periods by comparing a triangular wave and a sine wave having an amplitude ratio set at each value of a modulation factor, and selecting one pattern corresponding to an instructed modulation factor, and a unit for applying a controlled voltage, set at low and high levels in response to first and second periods of the selected pattern, to a generator. The triangular wave has a cycle duration obtained by dividing the cycle duration of the generator by product of 3 and odd number, a crest having a level higher than the sine wave at a timing of each first period, and a trough having a level lower than the sine wave at a timing of each second period.

The invention relates to a gas parameter online measurement method based on wavelength modulation spectroscopy and belongs to the field of tunable diode laser absorption spectroscopy. According to the method, a gas absorptivity function is fitted by using an odd number of harmonic signals of an X axis and a Y axis output by a phase-locked amplifier based on the wavelength modulation spectroscopy, normalization processing is carried out on the harmonic signals of the X axis and the Y axis by using first harmonic background signals so as to eliminate the influence of factors, such as background signal, laser intensity and modulation factor, and then, the temperature, concentration, pressure and spectroscopic constant of gas are directly measured by using the gas absorptivity function. The gas parameter online measurement method based on the wavelength modulation spectroscopy has the advantages that the problem that the wavelength modulation spectroscopy needs to calibrate experimental measuring temperature and concentration and cannot measure the pressure and spectroscopic constant of gas nowadays is solved, and the application range of the wavelength modulation spectroscopy is widened.

An inter-symbol interference (ISI) pattern-weighted early-late phase detector is provided. I and Q clocks are generated. The I clock frequency is divided by n, creating a reference clock. A serial data stream is sequentially sampled with the I clock, and with Q clocks having fixed and varied phase delays from the I clock, creating digital I-bit and Q-bit values. The I-bit values and Q-bit values are segmented into n-bit digital words. I clock phase corrections are identified and a modulation factor is determined in response to comparing Q-bit values sampled by the varied delay Q clock. Also identified are bit sequence patterns associated with each I-bit value. Each I-bit value is weighted in response to the identified bit sequence pattern and the identified I clock phase correction. The modulation factor is applied to the weighted average, and I and Q clock phase error signal are generated.

A photovoltaic power generation controller, in which minute power change is detected even with a low-resolution AD converter, thereby being capable of performing maximum power point tracking control with high accuracy, is provided. In the photovoltaic power generation controller of the invention, a control circuit 44 shifts switches 41 to respective output A sides of a voltage detector 8 and a current detector 9; gives a low-frequency ripple component to an operating voltage of a solar cell 1 while increasing modulation factor D by predetermined variation width d, to start maximum power point search from an open circuit voltage side; confirms a maximum power point passage when: an operating point oscillates in the vicinity of the maximum power point; and a power value, which is output by a power detector 43, after update of the modulation factor becomes smaller than a power value before update of the modulation factor; and switches the switches 41 to respective output sides of amplifiers 23 and 24 to continue the maximum power point tracking control.

Under oscillation-reducing control executed while PWM control is performed, an oscillation-reducing torque that is opposite in phase to a varying component of the motor revolution number is generated and, a final torque command value that is the sum of the oscillation-reducing torque and a torque command value is used to drive an AC motor. In a transition state where the PWM control mode is switched to overmodulation control mode, the oscillation-reducing torque that is determined by multiplying an oscillation-reducing torque by a correction coefficient that varies depending on a modulation factor gradually decreases as the correction coefficient decreases and substantially becomes zero when the control mode is switched. Thus, the oscillation-reducing torque has no stepped portion that occurs in the oscillation-reducing torque when the control mode is switched. Thus, oscillations in output torque of the AC motor can be reduced.

The invention provides a high-gain Z-source inverter, comprising a three-phase inverter, which is composed of a direct-current voltage source and a three-phase inversion bridge. The high-gain Z-source inverter further comprises a Z-source network, which is composed of a power diode, a switch inductor and a capacitor. The high-gain Z-source inverter is characterized in that a single inductor is replaced by a branch circuit of the switch inductor; the head end of the Z-source network is connected with the positive electrode of a power supply; the tail end of the Z-source network is connected to the positive end of the three-phase inversion bridge; and the inversion bridge and the power supply are grounded commonly. Compared with the traditional Z-source inverter, the Z-source inverter disclosed by the invention is capable of improving the boost capacity of the inverter, realizing a high modulation factor and improving the output quality of the whole inverter; and simultaneously, the voltage stress of the Z-network capacitor can be effectively reduced so as to reduce the volume and the weight of the inverter.

In a wireless tag with which a wireless communication system whose electric power of a carrier wave from a R/W is high, an overvoltage protection circuit is provided to prevent from generating excessive electric power in the wireless tag when the wireless tag receives excessive electric power. However, as noise is generated by operation of the overvoltage protection circuit, an error of reception occurs in receiving a signal whose modulation factor is small. To solve the problem, the maximum value of generated voltage in the wireless tag is held in a memory circuit after the overvoltage protection circuit operates, then the overvoltage protection circuit is controlled in accordance with the maximum value of generated voltage. The voltages at which the overvoltage protection circuit starts and stops operating are different from each other, and hysteresis occurs between the timing when the overvoltage protection circuit starts and stops operating.

The invention discloses a measuring device and a measuring method for frequency response of a mach-zehnder electrooptical modulator, which belong to the field of photoelectronic technologies, and aim at overcoming the problems of low frequency resolution, difficult calibration and high bandwidth requirement in the existing measurement. The measuring method comprises the steps of: transmitting a beam of light carrier into a mach-zehnder electrooptical modulator to be measured directly, utilizing a first signal source and a second signal source which are applied on a driving electrode and a third signal source applied on a bias electrode of the mach-zehnder electrooptical modulator to be measured for modulation, wherein the first signal source and the second signal source output sinusoidal signals with frequency difference, and the third signal source outputs a low-frequency signal; transmitting a light modulation signal into a photoelectric detector directly to perform beat frequency operation, extracting amplitudes of three specific frequency mixed signals from a beat frequency signal, and acquiring a modulation factor and a half-wave voltage of the mach-zehnder electrooptical modulator to be measured at single modulation frequency; and scanning frequency of an RF signal to obtain frequency response of the mach-zehnder electrooptical modulator to be measured.

The invention relates to the flexible direct-current transmission (VSC-HVDC) field, specifically to a modularized multi-level voltage source type converter-based loss determination method. The method comprises the following steps of 1) determining current of a single-phase voltage source type converter; 2) determining conduction loss of the voltage source type converter; 3) determining switch loss of the voltage source type converter; and 4) determining three-phase total loss of the voltage source type converter. The method provided by the invention effectively solves and obtains average current and effective current of an upper half bridge arm insulated gate bipolar transistor IGBT/an lower half bridge arm freewheeling diode FWD or an upper half bridge arm freewheeling diode FWD/a lower half bridge arm insulated gate bipolar transistor IGBT of a sub-module of the converter, thereby being capable of reflecting the relationship between the loss of the insulated gate bipolar transistor IGBT and the freewheeling diode FWD in the sub-module and the modulation factor, power factor, active transmission power, and the like of a flexible direct-current transmission system and thus enabling complex problems to be visualized.

The invention discloses a dual-mode SVPWM overmodulation method. The method comprises the steps that a modulation area is divided into a linear modulation area, a first overmodulation area and a second overmodulation area according to a modulation factor, wherein when an MI is larger than 0 and smaller than 0.9069, it is the linear modulation area, when the MI is larger than 0.9069 and smaller than or equal to 0.9517, it is the first overmodulation area, when the MI is larger than 0.9517 and smaller than or equal to 1, it is the second overmodulation area, and the MI is the modulation factor; a traditional SVPWM modulation method is used in the linear modulation area; a reference angle is used for controlling the compensation of an actual output voltage vector in the first overmodulation area; the mode that the actual output voltage vector hops at the position where a phase angle is a keep angle is used in the second overmodulation area, and the mode that an expected output voltage vector is followed by hopping is used for controlling the track of the output voltage vector. Compared with a traditional dual-mode control method, the dual-mode SVPWM overmodulation method is simple in algorithm, avoids complex operations, and is prone to engineering realization. Meanwhile, compared with a single-mode control method, the dual-mode SVPWM overmodulation method is high in control precision, and good in output voltage continuity.

A power converting apparatus comprises a DC-DC converter circuit that steps up or steps down an input voltage from a DC power supply, a DC-AC converter circuit that converts an intermediate voltage outputted by the DC-DC converter circuit to an alternate current, and a control circuit that controls the DC-DC converter circuit and the DC-AC converter circuit. The control circuit is provided with a circuit control unit that controls the DC-DC converter circuit so that the modulation factor, which is the amplitude ratio between a signal wave for manipulating the DC-AC converter circuit and the carrier wave therefor, will become a target modulation factor.

The invention provides a compensation system and method of an OLED display panel. The compensation system comprises a gray scale input module, a weighting modulation module, a compensation calculationmodule, a digital-to-analogue conversion, OLED sub-pixels and a current monitoring module. The compensation calculation module can calculate target feedback current corresponding an initial gray scale according to the initial gray scale input through the gray scale input module and pre-measured modulation factor and maximum feedback current and calculate a weighting coefficient according to the target feedback current and actual feedback currents, monitored by the current monitoring module, of the OLED sub-pixels, the weighting modulation module can adjust initial gray scale according to theweighting coefficient to obtain target gray scale and utilize the target gray scale to lighten the OLED sub-pixels, the uniform display phenomenon caused by ageing of organic light emitting diodes themselves can be compensated, the storage space required by the compensation system is decreased, and the picture uniformity of the display panel is improved.

A method for sending data includes obtaining data packets to be sent and modulating, by each transmit diversity branch, the data packets by using modulation mode corresponding to the each transmit diversity branch, and sending the modulated data packets. The modulation modes form a preset optimized combination of modulation modes. A different modulation mode corresponds to a different group of modulation factors and/or different group of constellation modulation symbols. The different groups of modulation factors comply with a preset modulation factor mapping relationship. The different groups of constellation modulation symbols comply with a preset constellation modulation symbol mapping relationship.

The invention provides an angle-time delay domain pilot frequency multiplexing broadband mass MIMO (multiple input multiple output) communication method. The method includes that a base station wirelessly communicates with multiple subscribers on each subcarrier; a probe sequence of each subscriber is generated via a same constant modulus sequence by means of frequency domain modulation, the different subscribers send uplink probe signals on multiple subcarriers of one or more continuous OFDM (orthogonal frequency division multiplexing) symbols simultaneously, and the base station acquires angle-time delay domain two-dimensional statistics channel information according to the uplink probe signals and determines pilot frequency modulation factors of all the subscribers according to the angle-time delay domain two-dimensional statistics channel information; a pilot frequency sequence of each subscriber is generated via the same constant modulus sequence by means of frequency domain modulation, the different subscribers send uplink pilot frequency signals on the multiple subcarriers of the one or more continuous OFDM symbols simultaneously, and the base station acquires channel estimation values of a pilot frequency band and a data segment of each subscriber according to the uplink pilot frequency signals; on each subcarrier, the base station implements uplink and downlink robust transmission according to the channel estimation values and estimation error space correlation matrixes. By the method, system pilot frequency overhead can be lowered, and system frequency spectrum and power efficiency is improved.

The invention discloses a high-precision fast face detection method, which relates to the technical field of face recognition. The method guarantees the detection speed and improves the accuracy of face recognition by designing lightweight network structures such as fast digestion convolution layer and multi-scale convolution layer, and combining with a new anchor point densification strategy. Atthat same time, the dynamic scale cross entropy is obtained by combining the modulation factor with the standard cross entropy loss remodeling, so as to construct a brand-new loss function, In order to solve the problem of extreme foreground background imbalance, while ensuring the detection speed, the facial recognition accuracy is further improved. Ultimately, it can not only run on a single CPUat the speed of 65FPS, but also significantly improve the recall rate of the small face, which fully meets the needs of the project.

A method of controlling bandwidth allocation over a communications link comprising detecting, by a processor, a change in a power level of a composite signal transmitted by a transmitter, the composite signal comprising a plurality of carrier signals and having a constant center frequency and spectral allocation, adjusting at least one of a modulation factor and a forward error correction (FEC) rate of one or more of the plurality of carrier signals using a modulator, in response to the change in power level to maintain a predetermined data rate and spectral allocation of the composite signal, and maintaining, by the modulator, an uninterrupted communications link between the transmitter and a remote receiver while the at least one of the modulation factor and the FEC rate is adjusted.

The invention relates to a pulse laser number optimizing method which is used for optimizing the pulse laser number of a single-particle overturn cross section of a pulse laser tester. The pulse laser number F of a certain pulse energy Ei is determined by the steps of 101) obtaining the light-spot area tau and the area delta of a single function unit of the tester under the laser energy; 102) obtaining a decided reference value, which is the ratio of the light-spot area tau to the area delta, of the laser number; and 103) determining the laser number according to the light-spot area when the decided reference value is greater than 1, and determining the laser number according to the area of the single function unit when the decided reference value is lower than 1. When the decided reference value n is greater than 1, the laser amount F=1/ktau; when n is lower than 1, the laser amount F=1/kdelta; and k represents a modulation factor whose value range is from 1 to 25.

The invention discloses a video image coding method and device. The method and the device are used for solving the problems that in the prior art, when a video coding JND model is used for coding a video image, generated data after coding is carried out comprise vision redundant information, the complexity of the coding process is high, and the subjective video coding performance is low. According to the method and the device, effective block classification is carried out on a video image corresponding to the current frame, luminance modulation factors are introduced into a pixel-level JND value of a traditional DCT region for obtaining the pixel-level JND value of the DCT region, in the process of obtaining macro-block level QP offset, canny operators do not need to be used, and therefore the coding complexity is reduced; moreover, in the coding process of the video image, the visual characteristic of the human eyes is taken into consideration, and block level vision sensitivity factors are added when a macro-block level QP is obtained, so that vision redundant information of generated data after the video image is coded is reduced, and the subjective video coding performance is improved.

The invention particularly discloses colorant matrix resin for unsaturated polyester resin and a preparation method thereof. The colorant matrix resin is formed by conducting copolymerization on acid, dihydric alcohol and auxiliaries, wherein the acid comprises unsaturated acid and saturated acid, the molar ratio of the unsaturated acid to the saturated acid is 0.1-1 to 1, the dihydric alcohol comprises polyethylene glycol, the polyethylene glycol accounts for 1%-50% of the total mass of addition of synthesis materials, the molecular weight of the polyethylene glycol ranges from 200 to 2,000, and the molar ratio of the dihydric alcohol to the acid is 1-5 to 1. According to the colorant matrix resin for the unsaturated polyester resin and the preparation method thereof, due to the fact that polyethylene glycol with different molecular weights and different mass fractions is selected, the viscosity modulation factor of the colorant matrix resin is greatly increased, the compatibility of an organic molecular chain and an inorganic substance is improved, the compatibility of the colorant matrix resin and inorganic color powder and the wettability of the colorant matrix resin and inorganic filler are promoted, the compatibility of the colorant matrix resin and unsaturated polyester is improved, and the tinting strength of the colorant matrix resin and a product and the capacity of resisting discoloration in the later using process of a finished product of unsaturated polyester resin are greatly improved.

The invention discloses a visual perceptual coding method based on a multi-domain JND (Just Noticeable Difference) model and relates to video information processing. The method comprises the following steps: respectively calculating a space-domain basic JND threshold value, a luminance masking modulation factor, a contrast masking modulation factor and a time domain masking modulation factor of each transformation coefficient in a DCT (Discrete Cosine Transform) block by utilizing a time-space-domain multi-domain JND model so as to obtain the time-space-domain multi-domain JND threshold value of each transformation coefficient; introducing a block perception-based distortion probability evaluative criteria in the transform coding process, and searching a correction factor of each coefficient relative to the JND threshold value through an adaptive searching algorithm so as to obtain a transformation coefficient suppression value; and finally, subtracting the original transformation coefficient from the most appropriate suppression value obtained through corresponding calculation, and taking the coefficient as a novel coefficient to be put at an entropy coding stage. According to the coded suppression strategy of the multi-domain JND model and the block perception-based distortion probability, the coding rate can be effectively reduced on the premise of guaranteeing certain subjective quality, and the compression ratio of the current coding standard is further improved.

In order to set optimum laser power for a disk smoothly and appropriately with a small number of times of test writing, an integrated value Sn is obtained from each kind of laser power Pwn set for the test writing and the modulation factor m(Pwn) of a reflection light intensity obtained through the test writing with the laser power Pwn using an expression “Sn=m(Pwn)×Pwn²”, laser power Pwth is obtained at which the modulation factor m(Pwn) becomes zero when relational characteristics of the integrated value Sn and the laser power Pwn are linearly approximated, and optimum laser power Pw is set based on the laser power Pwth. Here, the optimum laser power Pw is obtained from the target γ value of the disk using an expression “Pw=Pwth×{1+1/(γ+1)}”. The target γ value is obtained from an ADIP of the disk.

The invention discloses a testing circuit and testing method for a temperature rise of an IGBT module of a frequency converter. With the circuit and method, problems that the testing time is long, the loss power is high, and testing is limited by equipment during temperature rise testing on the IGBT module of the frequency converter can be solved. A controller exerts a PWM pulse signal on a measured module and modulation factors and phase angles of each group of IGBT modules are changed, so that the control way is simple. Circulation of active units and passive units in a closed loop formed by a first group of measured IGBT modules, a second group of measured IGBT modules, and a load reactor can be realized, thereby realizing circulated flowing of the energy between the two groups of IGBT modules and the load reactor; and the power grid only provides the loss power part, thereby substantially reducing the testing cost. Moreover, a PLC monitors information of currents, voltages, temperatures and faults of the measured IGBT modules in real time. Only a direct-current bus needs to be connected externally and the controller and the load reactor can employ internal devices of the frequency converter, so that the testing requirements can be met easily; the occupied area is small; and the time for construction of the testing platform is short.

An AC electric motor (M1), an inverter (14) and a controller (30) are mounted on an electric powered vehicle. The controller (30) includes a voltage deviation calculating unit (320), a modulation factor calculating unit (340), and a mode switching determination unit (360). The voltage deviation calculating unit (320) calculates a voltage deviation between a first voltage command when the rectangular wave voltage control is executed and a second voltage command when pulse width modulation control is executed, by inputting a current deviation to a voltage equation of the AC electric motor. Modulation factor calculating unit (340) calculates the modulation factor based on the first voltage command and the voltage deviation. The mode switching determination unit (360) determines whether or not control mode of the AC electric motor (M1) from the rectangular wave voltage control to the pulse width modulation control is necessary, based on the modulation factor.