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541 results about "Overmodulation" patented technology
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Overmodulation is the condition that prevails in telecommunication when the instantaneous level of the modulating signal exceeds the value necessary to produce 100% modulation of the carrier. In the sense of this definition, it is almost always considered a fault condition. In layman's terms, the signal is going "off the scale". Overmodulation results in spurious emissions by the modulated carrier, and distortion of the recovered modulating signal. This means that the envelope of the output waveform is distorted.
Space vector PWM modulator for permanent magnet motor drive
Owner:INFINEON TECH AMERICAS CORP
Control Device and Corresponding Control Method for a Boost Converter in a Motor Drive System
ActiveUS20090108794A1Reduce the valueSingle-phase induction motor startersHybrid vehiclesPower inverterMotor drive
A boost converter boosts a DC voltage of a DC power supply. An inverter converts the output voltage of the boost converter into an AC voltage. An AC motor is driven by the output voltage of the inverter. A control device which controls the boost converter reduces an output voltage instruction value of the boost converter in the case where the rotation speed of the AC motor is decreased and an absolute value of a variation rate of the rotation speed is not less than a predetermined value. The inverter is controlled in the control mode selected from a plurality of control modes including three modes of a sine wave PWM control mode, an overmodulation PWM control mode and a rectangular wave control mode. The control device of the boost converter reduces the output voltage instruction value of the boost converter only in the case where the control mode of the inverter is the rectangular wave control mode or the overmodulation control mode.
Owner:DENSO CORP
Wireless signal transmission system, method apparatus
InactiveUS6215981B1Reduce distortion problemsConvenient and economical operationTelevision system detailsHeadphones for stereophonic communicationCarrier signalEngineering
Systems, methods and apparatus are provided for conducting local wireless audio signal transmissions from a local audio signal source to a person within a local signal transmission area. In certain embodiments, the transmissions are conducted over the 900 MHz local transmission band to a portable receiver unit supported on the headband of a stereo headphone unit. The receiver unit serves to down convert the 900 MHz signal to a local frequency band which is received by an FM receiver of the receiver unit which serves to reproduce the audio signals therefrom which are, in turn, converted to acoustic signals by electroacoustic transducers of the headphone. A transmitter unit includes a ceramic resonator stabilized FM transmitter, as well a filter for suppressing high frequency noise in an audio modulation signal, a stereo audio multiplexing unit utilizing a 3fH subcarrier and an overmodulation detection unit. In certain embodiments, the receiver unit is powered by a rechargeable battery which is recharged from the transmitter unit.
Owner:THOMSON LICENSING SA
Methods, systems and apparatus for overmodulation of a five-phase machine
InactiveUS20110221367A1Increase the output voltageElectronic commutation motor controlMotor/generator/converter stoppersVoltage vectorComputer module
Methods, system and apparatus are provided for overmodulation of a five-phase machine in a vector controlled motor drive system that includes a five-phase PWM controlled inverter module that drives the five-phase machine. Techniques for overmodulating a reference voltage vector are provided to optimize voltage command signals that control a five-phase inverter module to increase output voltages generated by the five-phase inverter module.
Owner:GM GLOBAL TECH OPERATIONS LLC
Current control method for improving output torque of permanent magnet synchronous motor overmodulation area
ActiveCN103595323AIncrease open loop gainInhibit currentElectronic commutation motor controlVector control systemsVoltage vectorDrive motor
The invention belongs to the technical field of controlling of power converters of driving motors, and relates to a current control method for improving the output torque of a permanent magnet synchronous motor overmodulation area. The method includes the steps that a PI controller is adopted to a rotating speed loop; a current controller based on resonance control is used for a dq shaft electric current loop, and parameter setting is carried out on the current controller; the PI controller is adopted in a field-weakening control link, and output of the PI controller serves as a d shaft current set value through an amplitude limiting link; according to set voltage vector dq shaft components output by the current controller, the duty ratio is calculated through an SVPWM overmodulation link, and a PWM signal driving motor is produced. The method suppresses current harmonics caused by flux weakening overmodulation, open-loop gains of the current loop are increased, and current, harmonic and torque fluctuation caused by overmodulation can be effectively suppressed.
Owner:TIANJIN UNIV
Methods, systems and apparatus for adjusting duty cycle of pulse width modulated (PWM) waveforms
ActiveUS20120169263A1Accurate currentReduce variations/errorsSingle-phase induction motor startersMotor/generator/converter stoppersPhase currentsMotor drive
Embodiments of the present invention relate to methods, systems and apparatus for controlling operation of a multi-phase machine in a vector controlled motor drive system when the multi-phase machine operates in an overmodulation region. The disclosed embodiments provide a mechanism for adjusting a duty cycle of PWM waveforms so that the correct phase voltage command signals are applied at the angle transitions. This can reduce variations / errors in the phase voltage command signals applied to the multi-phase machine so that phase current may be properly regulated thus reducing current / torque oscillation, which can in turn improve machine efficiency and performance, as well as utilization of the DC voltage source.
Owner:GM GLOBAL TECH OPERATIONS LLC
Electric current reconstructing and over-modulating device of air conditioning frequency converter and method thereof
InactiveCN101674046AImprove voltage utilizationReduce capacityAC motor controlVector control systemsFrequency changerDc current
The invention relates to an electric current reconstructing and over-modulating device of an air conditioning frequency converter, which is characterized by comprising an electric current reconstructing device, a vector controller, a pulse width modulation (PWM) frequency converter, a direct current side electric current sensor, an electric motor and a coder. The electric current reconstructing device comprises an SVPWM over-modulating module, a pulse width modulation (PWM) signal adjusting module, a direct current sampling module and an alternating current reconstructing module. An electric current reconstructing and over modulating method of the air conditioning frequency converter comprises the steps: sampling the direct current side electric current of the pulse width modulation (PWM)frequency converter at twice by the electric current reconstructing device; counting an approach vector switch action time which meets a minimum sampling time request according to the two sampling values; sampling the direct current side electric current at twice again in the approach vector switch action time; and reconstructing three phase alternating current according to the sampling values ofthe direct current at twice, thereby realizing the closed loop control of the pulse width modulation (PWM) frequency converter. The modulating method can be widely used for the field in reconstructingand over-modulating the electric current of the frequency converter in air conditionings and electric vehicles.
Owner:TSINGHUA UNIV
Dynamic Polarization Modulation and Control
ActiveUS20130279631A1Antenna arraysAmplitude demodulation by homodyne/synchrodyne circuitsSoftware engineeringWave form
A method for sending a data from an electromagnetic radiator by polarization modulation of an electromagnetic wave includes radiating from the radiator first and second electromagnetic waves including first and second polarizations respectively, the first polarization being different than the second polarization. The first and second electromagnetic waves form a third electromagnetic wave having a third polarization different from the first or second polarization. The method includes modulating the third polarization responsive to the data by modulating one or more parts of the third electromagnetic wave. The data is sent in the third polarization. A system for sending a data includes an oscillator adapted to generate an oscillating signal, and a phase shifter coupled to the oscillator and adapted to generate a first phase-shifted oscillating signal having a first phase. The phase shifter is adapted to vary the phase difference across a predefined range in response to the data.
Owner:CALIFORNIA INST OF TECH
Digital intermediate frequency conversion method and system used in repeater
ActiveCN101197606AHigh degree of integrationReduce usageFrequency-modulated carrier systemsRadio relay systemsProgrammable logic deviceUp conversion
The invention discloses a frequency changing method of digital middle-frequency signals used in a repeater station system, which comprises two steps of an up frequency changing process and a down frequency changing process: in the down frequency changing process, the middle-frequency signals after digital analog conversion are processed by digital wave filtering processes such as an extraction process, a bandpass compensation, a signal shaping process, etc. after a digital frequency mixing process, the middle-frequency signals can be moved to a zero middle-frequency, a digital signal with the high speed rate can extracted as two-channel quadrature digital baseband I, Q signal with a low speed rate; in the up frequency changing process, the digital baseband I, Q signals acquired from the down frequency changing process are processed by an interpolation filtering process, then processed by I, Q modulation process and a secondary frequency mixing process, and the signals can be processed by a gain adjustment and control, finally high speed digital middle-frequency signals are outputted. Correspondingly, the invention also discloses a frequency changing system thereof. The invention can be achieved by using PLC units such as FPGA, CPLD, EPLD and DSP, etc., which can improve the integration degree of repeater station equipment; meanwhile, an ASIC chip is removed to decrease heating capacity and to improve the reliability.
Owner:COMBA TELECOM SYST CHINA LTD
High voltage crossing control method of wind power full power converter
InactiveCN105375523ARealize high voltage ride through functionReduce upgrade costsSingle network parallel feeding arrangementsWind energy generationOvervoltageLoad circuit
The present invention provides a high voltage crossing control method of a wind power full power converter. When the network voltage suddenly increases over 1.1 times rated voltage, the transient overvoltage is restrained through an off-load circuit connected with a direct circuit bus, inductive reactive current relative to the network voltage is output through a decoupled active and reactive positive-and negative-sequence current controller to reduce the amplitude of the network voltage, and the occurrence of overmodulation is avoided through dynamic regulation of the voltage reference value of the direct current bus. According to the invention, a converter can operate without being dissociated from the power grid free of complex mode switch in the condition of a network voltage not larger than 1.3 times rated value, and an effective inductive reactive output is provided.
Owner:CORONA WIND EQUIP BEIJING CO LTD
Motor drive apparatus having oscillation-reducing control function for output torque
InactiveUS20060076914A1Reduce oscillationEfficient executionElectronic commutation motor controlDC motor speed/torque controlMotor driveModulation factor
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.
Owner:TOYOTA JIDOSHA KK
Fiber optic gyroscope using a low-polarization and polarization-maintaining hybrid light path
ActiveUS20100238450A1Reduce impactLow costSpeed measurement using gyroscopic effectsSagnac effect gyrometersLow noiseFiber coupler
A fiber optic gyroscope using a low-polarization and polarization-maintaining hybrid light path comprises an optical meter head and a circuit signal processing part, The optical meter head comprises: a light source, a multi-functional integrated optic chip, a detector, a coupler and a fiber coil, wherein the light source is a low polarization light source and single mode fiber pigtail coupling; the input terminal of multi-functional integrated optic chip uses a single mode fiber, and the output terminal of multi-functional integrated optic chip adopts a polarization-maintaining fiber; the input fiber pigtail of the said detector is a single mode fiber; the coupler is a 2×2 polarization independence single mode fiber coupler; the fiber coil is a polarization-maintaining fiber. By adopting the scheme of the low-polarization and polarization-maintaining hybrid light path and the signal processing methods such as all-digital closed loop control and random overmodulation etc., the present invention can reduce the effect of light path polarization crosstalk, simplify the assembling technology, enable large scale production and guarantee the good scale factor linearity performance and the lower noise level. Furthermore, by temperature modeling and compensating, the invention enables the bias of the fiber optic gyroscope to drift more slightly within the all-temperature range, and therefore the fiber optic gyroscope with good performance and engineering application can be achieved.
Owner:BEIJING AEROSPACE TIMES OPTICAL ELECTRONICS TECH
Ac motor drive control device and method
An AC motor drive control device includes a control mode judgment unit that performs a judgment based on required voltage amplitude required by a synchronous AC motor, in order to switch units for applying voltage to the AC motor to one of a rectangular wave voltage phase control unit, an overmodulation control unit, and a PWM current control unit.
Owner:DENSO CORP
Control device for ac motor
ActiveUS20110279071A1Process stabilityMotor/generator/converter stoppersAC motor controlVoltage amplitudeSuperimposition
An overmodulation PWM control unit includes a voltage amplitude calculating unit for calculating a voltage command amplitude of an original voltage command based on current feedback control, a voltage amplitude correcting unit performing linear compensation on the voltage command amplitude so that a fundamental amplitude of a pulse width modulation voltage provided from an inverter may match the original voltage command amplitude, and a harmonic determining unit for determining presence or absence of superimposition of a three-order harmonic component on a phase voltage command. The harmonic determining unit performs switching between presence and absence of the three-order harmonic component based on transition of the original voltage command amplitude to avoid passing through a change point where discontinuity occurs in the voltage amplitude characteristics representing a relationship between a fundamental amplitude obtained in advance for each of the cases of presence and absence of the superimposition of the three-order harmonic component and the voltage command amplitude required for achieving the fundamental amplitude.
Owner:DENSO CORP
Transceiver capable of causing series resonance with parasitic capacitance
ActiveUS7069062B2Improve communication qualityPrevent overall voltage from decreasingNear-field systems using receiversSubstation equipmentTransceiverResonance
A transceiver for inducing electric fields according to data to be transmitted in an electric field propagating medium, and carrying out at least data transmission by using induced electric fields, is formed by a transmission unit configured to modulate the data to be transmitted by generating alternating current signals having a prescribed frequency, and transmit modulated signals obtained by modulating the data to be transmitted, and a resonance causing unit configured to cause a series resonance with a parasitic capacitance appearing between a ground for the transmission unit and an Earth ground and a parasitic capacitance appearing between the electric field propagating medium and the Earth Ground.
Owner:NIPPON TELEGRAPH & TELEPHONE CORP
Transverse device array radiator ESA
An antenna array employing continuous transverse stubs as radiating elements is described, which includes an upper conductive plate structure comprising a set of continuous transverse stubs, and a lower conductive plate structure disposed in a spaced relationship relative to the upper plate structure. The upper plate structure and the lower plate structure define an overmoded waveguide medium for propagation of electromagnetic energy. For each of the stubs, one or more transverse device array phase shifters are disposed therein.
Owner:RAYTHEON CO
Overmodulation method and system for bi-level space vector pulse duration modulation
ActiveCN101442290ARelatively small errorEasy to calculateAC motor controlVoltage vectorVoltage reference
The invention relates to an overmodulation method for double-level space vector pulse width modulation. The method comprises: the modulation ratio is obtained from a reference voltage vector and direct current bus voltage; the modulation ratio is divided into a first setting region and a second setting region; when the modulation ratio is in the first setting region, the acting time of a zero vector and an effective vector is calculated; when the acting time of the zero vector is more than zero, a compensating coefficient is calculated; according to the compensating coefficient, the acting time of the zero vector and the effective vector after being compensated is calculated; when the acting time of the zero vector is less than or equal to zero, the zero vector does not act and the acting time of the effective vector is calculated; when the modulation ratio is in the second setting region, a keeping angle is calculated; the keeping angle is compared with a phase angle of the reference voltage vector, and according to a comparison result, the acting time of the effective vector in different regions is calculated respectively; and according to the acting time, the method carries out overmodulation. The method is simple to calculate and convenient to realize a project and improves precision of SVPWM so as to reduce relative error between the output voltage and the reference voltage vector.
Owner:ZHUZHOU CSR TIMES ELECTRIC CO LTD
Analog-digital mixing modulation recognition device and digital modulation recognition device based on parallel judgment
InactiveCN101834819AImprove recognition accuracyAvoid the problem of order of useModulated-carrier systemsPattern recognitionPhase shifted
The invention discloses an analog-digital mixing modulation recognition device and a digital modulation recognition device based on parallel judgment, belonging to the communication field. The invention aims to solve the problems of low precision rate and long recognition time for providing a judgment tree by A.K. N and E.E.A zzouz. The invention is characterized in that the parallelly judged analog-digital mixing modulation recognition device comprises the following steps: a modulation signal receiving module coarsely classifies the received modulation signals through an instantaneous characteristic normalization module and a modulation mode characteristic parameter extraction module, and then the received modulation signals are particularly classified through an amplitude shift keying modulation judgment ouput module, a phase shift keying modulation judgment output module and a frequency shift keying modulation judgment output module. Compared with the analog-digital mixing modulation recognition device, the digital modulation signals received by the digital modulation recognition device based on parallel judgment have different inner structures of the modules when coarse classification and particular classification are conducted.
Owner:HARBIN INST OF TECH
Digital signal transmission and reception
A digital signal transmitter in which multiple data streams are each transmitted by modulation of a respective frequency band within one of a group of frequency channels, the frequency bands each occupying no more than a predetermined maximum bandwidth less than or equal to the channel width; comprises means for transmitting at respective frequency positions within each frequency channel, one or more instances of band information defining the frequency bands corresponding to all of the data streams carried within that frequency channel, the one or more instances being arranged so that any portion of the frequency channel equal in extent to the predetermined maximum bandwidth includes at least one instance of the band information.
Owner:SONY CORP
Measuring method for fiber optic gyroscope eigenfrequency
The invention provides a measuring method for fiber optic gyroscope eigenfrequency, which is based on the fiber optic gyroscope eigenfrequency measuring system of even double frequency eigenfrequency square wave phase overmodulation, wherein the light path adopted by the measuring system is completely identical with that of the actual gyroscope; and the typical light path includes a light source, a coupler, a Y waveguide, a fiber loop and a photoelectric detector. Compared with the existing method, the measuring method reduces the strict requirements for the square wave modulated signal quality, has the advantages of simple method, low cost and easiness for realization, and can greatly improve the measuring precision of the eigenfrequency on the basis that the existing gyroscope does not require additional hardware.
Owner:BEIHANG UNIV
Ac motor drive controller
ActiveUS20100127656A1Single-phase induction motor startersAC motor controlVoltage amplitudeCarrier signal
An overmodulation PWM controller includes a voltage instruction calculation unit which calculates a d axis voltage instruction and a q axis voltage instruction in which a voltage amplitude exceeds a peak value of a triangular wave carrier; a voltage instruction correction unit which corrects the d axis voltage instruction and the q axis voltage instruction so that a pulse width modulation voltage applied to an AC motor has a fundamental wave amplitude corresponding to the voltage instruction amplitude, according to the synchronization value K which is the number of the triangular carriers per one cycle of the phase voltage instruction; and a voltage instruction conversion unit which converts the corrected d axis voltage instruction and the q axis voltage instruction into a phase voltage instruction. The pulse width modulation voltage is controlled according to the result of comparison between the phase voltage instruction and the triangular wave carrier.
Owner:DENSO CORP
Methods, systems and apparatus for controlling third harmonic voltage when operating a multi-phase machine in an overmodulation region
InactiveUS20120187876A1Increased torque densityImprove mechanical powerElectronic commutation motor controlMotor/generator/converter stoppersVoltage vectorMotor drive
Methods, system and apparatus are provided for controlling third harmonic voltages when operating a multi-phase machine in an overmodulation region. The multi-phase machine can be, for example, a five-phase machine in a vector controlled motor drive system that includes a five-phase PWM controlled inverter module that drives the five-phase machine. Techniques for overmodulating a reference voltage vector are provided. For example, when the reference voltage vector is determined to be within the overmodulation region, an angle of the reference voltage vector can be modified to generate a reference voltage overmodulation control angle, and a magnitude of the reference voltage vector can be modified, based on the reference voltage overmodulation control angle, to generate a modified magnitude of the reference voltage vector. By modifying the reference voltage vector, voltage command signals that control a five-phase inverter module can be optimized to increase output voltages generated by the five-phase inverter module.
Owner:GM GLOBAL TECH OPERATIONS LLC
Parametric amplification of a MEMS gyroscope by capacitance modulation
ActiveUS20090320591A1Acceleration measurement using interia forcesSpeed measurement using gyroscopic effectsCapacitanceGyroscope
Parametric amplification of the output of a MEMS gyroscope is achieved by modulating the sense capacitance, or an auxiliary capacitance having an applied DC voltage. The capacitance modulation is produced by the driven motion of the gyroscope mechanism, so the pump signal of the parametric amplifier is not subject to phase errors in the electronics. The capacitance modulation affects the mechanical gain of the sensor (transfer function from input force to sensor mechanism displacement), as well as the electrical gain of the sensor (transfer function from sensor mechanism displacement to output electrical signal). The mechanical and electrical gains of the sensor become phase-dependent, so the Coriolis rate signal can be amplified while the unwanted quadrature-phase signal is attenuated.
Owner:HONEYWELL INT INC
Motor drive apparatus having oscillation-reducing control function for output torque
InactiveUS7199540B2Reduce oscillationEfficient executionElectronic commutation motor controlDC motor speed/torque controlMotor driveModulation factor
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.
Owner:TOYOTA JIDOSHA KK
Motor drive apparatus having oscillation-reducing control function for output torque
InactiveCN1767370APrevent step partReduce vibrationAC motor controlPropulsion using engine-driven generatorsTransient statePhase variation
The present invention relates to a motor drive device having a vibration reduction control function for output torque. Under the condition that vibration reduction control is performed while PWM control is performed, a vibration reduction torque (Δtr) whose phase is opposite to that of the motor revolution variation component is generated, and the vibration reduction torque (Δtr) and the torque The final torque command value (TR) of the sum of the command values (TR0) is used to drive the AC motor (M1). In the transitional state where the PWM control mode is switched to the overmodulation control mode, the vibration reducing torque (Δtr) determined by multiplying the vibration reducing torque (Δtr0) by the correction coefficient (Km) according to the modulation rate changes along with The correction coefficient (Km) decreases gradually, and becomes almost zero when the control mode is switched. Thus, the vibration reducing torque (Δtr) does not have any step portion that occurs in the vibration reducing torque (Δtr0) at the time of switching the control mode. Therefore, the vibration of the output torque of the AC motor can be reduced.
Owner:TOYOTA JIDOSHA KK
Two-level three-phase space vector pulse-width modulation device and SVPWM optimization method thereof
InactiveCN103715956AImplement linearizationEasy to implementElectronic commutation motor controlVector control systemsComputer moduleLinear modulation
The invention discloses a two-level three-phase space vector pulse-width modulation device and an SVPWM optimization method thereof. Aiming at influence of dead-zone time and narrow pulse-width limit, a practical linear modulation zone is expanded, an over-modulation algorithm is optimized and linear processing of an over-modulation zone is simply realized. The two-level three-phase space vector pulse-width modulation device comprises six modules of a given reference voltage correction module, a voltage coordinate transformation module, a voltage interval calculating module, a vector time calculating module, a modulation algorithm optimization module and a PWM comparison point time calculating module. Bus voltage is fully utilized via the simplest algorithm so that linearity of output fundamental wave voltage is enhanced and total harmonic wave distortion of the output voltage is reduced.
Owner:SOUTH CHINA UNIV OF TECH
Rotary electric machine control system
InactiveUS20100072925A1Improve efficiencyAC motor controlDC motor speed/torque controlElectric machineControl system
A control unit for a rotary electric machine control system includes a first current command module, a second current command module and a change module. The first current command module controls the rotary electric machine based on a maximum efficiency characteristic line. The second current command module controls the rotary electric machine based on an early switching characteristic line, which is set at a retard angle side relative to the maximum efficiency characteristic line with a predetermined phase difference. When a control mode is switched over to a rectangular wave voltage phase control mode from an overmodulation current control mode in accordance with an increase in torque, the change module changes the current command from the first current command module to the second command current module.
Owner:DENSO CORP
Dual-mode SVPWM overmodulation method
ActiveCN103580519AHigh control precisionImprove continuityDc-ac conversion without reversalVoltage vectorDual mode
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.
Owner:HUAZHONG UNIV OF SCI & TECH
Carrier inhibiting method for radio frequency identification reader-writer and radio frequency device
ActiveCN102222246ACarrier CancellationCo-operative working arrangementsSensing record carriersCarrier signalEngineering
The invention relates to a carrier inhibiting method for a radio frequency identification reader-writer, which comprises the following steps of: processing a received signal to obtain two paths of orthogonal baseband signals, obtaining an initial phase valve and an amplitude valve of a cancelling signal by use of two paths of orthogonal baseband signals; carrying out iterative operation on the initial phase value of the cancelling signal to obtain a target phase valve of the cancelling signal; and generating the cancelling signal, and overlapping the cancelling signal to the received signal after modulation. The invention also relates to a radio frequency device of the radio frequency identification reader-writer. By implementing the carrier inhibiting method for the radio frequency identification reader-writer and the radio frequency device in the invention, the beneficial effect that the carrier of the reader-writer per se in a receiving channel can be effectively cancelled is achieved.
Owner:INVENGO INFORMATION TECH
Improved overmodulation method for diode clamped three-level inverter
InactiveCN103051230AReduced output voltage rangeAvoid the problem of direct jumpAc-dc conversionCapacitanceVoltage vector
The invention relates to an improved overmodulation method for a diode clamped three-level inverter. The method comprises the following steps: 1, obtaining a synthesized reference voltage vector V*ref according to the diode clamped three-level inverter; 2, defining a modulation degree function of the synthesized reference voltage vector V*ref, and determining a modulation region in which the synthesized reference voltage vector V*ref of the three-level inverter is positioned according to a value range of the modulation degree function; 3, correcting amplitudes of the synthesized reference voltage vector in a first overmodulation region and a second overmodulation region where the synthesized reference voltage vector of the inverter is positioned, and a phase angle of the synthesized reference voltage vector; and 4, modulating corrected voltage vectors Vref in the first and second overmodulation regions by using a virtual space vector-based nearest three vector (NTV) method. By the method, neutral-point voltage fluctuation of a capacitor on the direct-current side can be adjusted, output level is prevented from directly jumping between positive level and negative level without passing zero level, and the inverter is guaranteed to stably work in an overmodulation region.
Owner:SHANGHAI UNIV
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