347 results about "Harmonic mitigation" patented technology

A harmonic suppression mixer for down converting an RF signal to a complex I and Q baseband signal that uses a plurality of switching mixers each with a gain stage to produce a sinusoidal weighted sum of the mixer outputs. Odd harmonics output by each switching mixer is suppressed in the composite signal. A low skew local oscillator (LO) clock generator creates multiple LO phases and drives the mixers. The mixer can be used in low noise direct conversion RF tuners. The mixer is configurable by programming gain stage coefficient values to achieve a variable number of effective mixers used in combination. At low tuning frequencies, all available mixers are programmed with unique coefficients and driven by different LO clock phases to achieve maximum harmonic suppression. At high tuning frequencies, some mixers are paralleled and duplicate coefficients are programmed or mixers are disabled to reduce the number of effective mixers.

A harmonic suppression mixer for down converting an RF signal to a complex I and Q baseband signal that uses a plurality of switching mixers each with a gain stage to produce a sinusoidal weighted sum of the mixer outputs. Odd harmonics output by each switching mixer is suppressed in the composite signal. A low skew local oscillator (LO) clock generator creates multiple LO phases and drives the mixers. The mixer can be used in low noise direct conversion RF tuners. The mixer is configurable by programming gain stage coefficient values to achieve a variable number of effective mixers used in combination. At low tuning frequencies, all available mixers are programmed with unique coefficients and driven by different LO clock phases to achieve maximum harmonic suppression. At high tuning frequencies, some mixers are paralleled and duplicate coefficients are programmed or mixers are disabled to reduce the number of effective mixers.

A harmonic suppression mixer for down converting an RF signal to a complex I and Q baseband signal that uses a plurality of switching mixers each with a gain stage to produce a sinusoidal weighted sum of the mixer outputs. Odd harmonics output by each switching mixer is suppressed in the composite signal. A low skew local oscillator (LO) clock generator creates multiple LO phases and drives the mixers. The mixer can be used in low noise direct conversion RF tuners. The mixer is configurable by programming gain stage coefficient values to achieve a variable number of effective mixers used in combination. At low tuning frequencies, all available mixers are programmed with unique coefficients and driven by different LO clock phases to achieve maximum harmonic suppression. At high tuning frequencies, some mixers are paralleled and duplicate coefficients are programmed or mixers are disabled to reduce the number of effective mixers.

A system for controlling a permanent magnet synchronous motor calculates fundamental a d-axis (or q-axis) voltage command based on a difference between a d-axis (or q-axis) current command and a d-axis (or q-axis) current feedback signal, calculates a harmonic suppression d-axis (or q-axis) voltage command used to suppress at least one higher-order harmonic current component included in a harmonic current component which is calculated based on the differences between the current feedback signals and the current commands, and calculates a d-axis (or q-axis) voltage command by adding the fundamental d-axis (or q-axis) voltage command and the harmonic suppression d-axis (or q-axis) voltage command. The d-axis and q-axis voltage commands are transformed into three-phase voltage commands, which are converted into a drive voltage for driving the permanent magnet synchronous motor. As a result, the harmonic current components are significantly suppressed and the motor's overall performance is improved.

The invention discloses a method for inhibiting a harmonic wave of an energy-storage grid-connected three-phase voltage source transformer of a storage battery, which relates to the technical field of power grid in power industry. The method comprises the following steps of: acquiring signals of a voltage and a current of a three-phase power grid; converting the signals into two phases of fixed-axis variables serving as feedback quantities through Clark transformation and Park transformation; simultaneously calculating charging power; comparing feedback power with reference power; performing proportion integration (PI) regulation, and obtaining a reference voltage by comparing the feedback power and the reference power with two phases of feedback voltage values and performing the PI regulation; obtaining a required fixed coordinate system voltage of a three-phase current converter after performing the Clark transformation and the Park transformation; obtaining a harmonic current from the voltage by using a high-pass filter; transforming the harmonic current into a two-phase rotating coordinate system; and obtaining a harmonic compensation value by using a proportion resonance (PR) controller. By the method, a current harmonic wave generated by the current transformer can be inhibited in a targeted way; and half of proportion resonant controllers can be saved compared with a conventional proportion resonance control algorithm.

The invention discloses a low-voltage transformer district simulated practice training system based on a rural power grid intelligent low-voltage distribution box. The system comprises an intelligent low-voltage management master station system in a practice training room, and a simulated intelligent distribution transformer district and an intelligent ammeter of a low-voltage electric power user which are in the practice training room, wherein the intelligent low-voltage management master station system comprises a data storage server, a data processing server, a preposition server, a Web server, a gateway server, a database server and a management terminal. According to the low-voltage transformer district simulated practice training system based on the rural power grid intelligent low-voltage distribution box, the rural power grid intelligent low-voltage distribution box is served as a basic unit, real-time monitoring system simulation of electric power parameter simulating, controlling and managing is carried out on distribution transform and the low-voltage electric power user which are matched with the rural power grid intelligent low-voltage distribution box. Through the intelligent low-voltage management master station system in the practice training room, the distribution transform parameter monitoring, measuring, the electricity information collecting, the communicating, the dynamic reactive power compensation controlling, the harmonic restraining and the three-phase imbalance governing on the simulated intelligent distribution transformer district can be achieved, and the integrated application function of the electricity safety and the electric power facility protection real-time monitoring and early warning can be achieved.

The invention provides a high-power built-in permanent magnet synchronous motor position-sensorless control system and a control method, and belongs to the field of motor control. The control system solves the problem that when a traditional high-power built-in permanent magnet synchronous motor system works at a low switch frequency, low-order harmonic content increases, and meets the requirements that low-order harmonic waves are weakened and meanwhile, rotating voltage vector control with constant amplitude values is produced. An SHMPWM technique is adopted, it is guaranteed that on a low-switch-frequency work condition, harmonic waves of a high-power permanent magnet synchronous motor system are inhibited, constraint conditions of SHMPWM non-linear transcendental equation sets are increased, and three-phase specific harmonic wave content signals with constant amplitude values and 120-degree phase angle differences are extracted from the weakened harmonic wave content to be used for estimation of a rotor position; specific harmonic currents are obtained through a band-pass filter; by means of a position observer, the estimated rotation speed and the rotor position of a permanent magnet synchronous motor are obtained, and position-sensorless rotation speed closed loop vector control of a motor is achieved. The control system and the control method are suitable for control of the motor.

The invention discloses and especially relates to a secondary harmonic inhibition method for a broadband helix travelling wave tube, and belongs to the technical field of broadband helix travelling wave tubes. Within a certain range, a travelling wave tube harmonic inhibition situation becomes greater if a distance between a fin to a center is reduced, however, the reduced distance will make the fin closer to a helix and might cause engineering machining troubles and many other potential troubles. Therefore, two different fin structures are adopted by an input segment and an output segment respectively, and the distance from a fin on the input segment to the center is made to be greater. Through the even and symmetric fin structure, a better harmonic inhibition effect is exhibited, and other factors in terms of the design of a travelling wave tube can be better weighed.

A harmonic suppression resonator comprises a plurality of waveguide resonators that resonate in TE mode, in which harmonic suppression resonator, adjoining resonators are coupled via a plurality of coupling windows. Four coupling windows 33bc1, 33bc2, 33bc3 and 33bc4 are provided between a resonant region 51b and a resonant region adjoining the resonant region 51b. These coupling windows allow fundamental wave modes of the adjoining resonators to be coupled mainly by magnetically coupling. The coupling windows 33bc3 and 33bc4 allow second harmonic modes of the adjoining resonators to be electrically coupled, and the coupling windows 33bc1 and 33bc2 allow the second harmonic modes of the adjoining resonators to be magnetically coupled. By causing the amount of the electrically coupling and the amount of the magnetically coupling to be substantially equal, the coupling of the second harmonic modes is negated, whereby propagation of the second harmonic is blocked.

A local oscillator (LO) generator for driving a bank of mixers that provides precise phase relationship between multi-phase LO outputs comprises a shift register using slave-master-slave flip-flop elements. The LO generator can be used over a wide operating frequency range. The LO generator is suitable for driving a multi-phase LO clock input to a harmonic suppression mixer. A pattern generator produces a pattern signal and a reclocking signal that determines the frequency of the LO signals and the phase delay between the LO output phases.

A power supply device of a video display apparatus and a method thereof is capable of improving operation reliability of a video display apparatus, preventing erratic operation of the video display apparatus caused by higher harmonics and preventing erratic operation of other apparatus caused by unnecessary transmitted radiative wave. The power supply device can include a rectifying section for converting AC power into DC power, a harmonics suppressor for cutting off higher harmonics included in the DC power and a smoothing circuit for smoothing the higher harmonics cut-off DC power. A standby power supplier is for supplying the smoothed DC power to the video display apparatus as standby power, a main power supplier is for supplying the smoothed DC power to the video display apparatus as main power and a control unit is for controlling an operation of the harmonics suppressor.

The invention discloses a WiFi-frequency-band-based rectification antenna with harmonic wave suppression. The rectification antenna comprises a WiFi-frequency-band-based harmonic wave suppressing microstrip receiving antenna and a microstrip differential rectification circuit. The output end of the microstrip receiving antenna is connected with the input end of the microstrip differential rectification circuit. The microstrip differential rectification circuit includes a 50-ohm impedance wire, a branch T type impedance matching unit, a branch rectification unit, and a branch output filter and a load. The 50-ohm impedance wire is used as the input end at the input port of the microstrip differential rectification circuit and is connected with the output end of the receiving antenna. The output end of the input port leads out two branches. The input ends of the two branches are connected through a T type knot and the output ends pass successively the branch impedance matching unit, the branch rectification unit, and the branch output filter, and is finally connected with the load. The diodes of the branch rectification unit are connected in reverse direction.

The invention discloses a second-order-odd-repetitive-controller-based odd harmonic current suppression method of a magnetic levitation rotor. A magnetic levitation rotor kinetic model including rotor mass unbalance and sensor harmonic is established; and a second-order-odd-repetitive-controller(SOORC)-based odd harmonic current suppression method of a magnetic levitation rotor is employed. The SOORC has a second-order inner membrane structure for odd harmonic frequency suppression, so that the harmonic suppression capability on a harmonic frequency changing or uncertain condition can be improved and thus the control robustness of the system for the harmonic frequency changing or uncertain condition can be improved. With phase hysteresis-lead compensation, the steady performance and dynamic performance of the system are improved, so that odd harmonic current components generated by a magnetic bearing coil in a magnetic levitation rotor can be suppressed. The method is suitable for suppression of odd harmonic current components of the magnetic levitation rotor system with rotor mass unbalance and sensor harmonic.

The invention discloses a multimode radio frequency power amplifier. The power amplifier comprises a common amplifier circuit for amplifying the power of an input radio frequency signal, a harmonic suppression circuit, a high-frequency-band common matching circuit, a high-frequency-band difference matching circuit and a low-frequency-band matching circuit, wherein the harmonic suppression circuit is connected with the input end of the high-frequency-band common matching circuit through a first switch and used for suppressing harmonic waves of signals at the GSM high frequency band or the TD-SCDMA frequency band; the high-frequency-band common matching circuit conducts impedance conversion matching on the received radio frequency signals at the GSM high frequency band, the TD-SCDMA frequency band or the LTE-TDD frequency band; the high-frequency-band difference matching circuit further conducts impedance conversion matching and / or harmonic suppression on the received radio frequency signals at the GSM high frequency band or the TD-SCDMA frequency band, and then sends the signals to a switch circuit; the low-frequency-band matching circuit conducts impedance conversion matching on the received radio frequency signals at the GSM low frequency band and sends the signals to the switch circuit. GSM, TD-SCDMA and LTE-TDD multimode radio frequency power is amplified with only one chip, circuit multiplexing and circuit sharing are used a lot, the integrity is high, the circuit structure is simple, and cost is low.

The invention discloses a multi-frequency output matching network applied to a GSM (Global System for Mobile Communications) radio-frequency power amplifier. The multi-frequency output matching network comprises a transformer; a winding having a center tap is adopted by a primary coil of the transformer; the center tap is connected with a working voltage; two ends of the primary coil are taken as a pair of differential input ends of the output matching network, and respectively receive a pair of differential signals output by an amplification circuit; one winding is adopted by a secondary coil of the transformer; one end of the secondary coil outputs a single ended signal, and the other end of the secondary coil is grounded; the primary coil of the transformer is further connected with an LC resonance circuit in parallel; and an output end of the secondary coil of the transformer is further taken as a single ended output end of the output matching network after being connected with an LC low pass filter circuit. The output matching network disclosed by the invention can provide impedance matching within a relatively wide frequency range, and further has excellent harmonic suppression effect.

The invention relates to a reading head optimization distribution method for angle encoder self calibration. The method comprises steps that a Fourier analytical method is employed to determine a transfer function of angle measurement error analysis and analyze characteristics; optimization targets are determined through comprehensively considering harmonic wave inhibition, random noise and calibration precision factors; initial parameters including the reading head number and the total calibration harmonic wave number and reading head mounting smallest angle interval constraint conditions aredetermined, and an optimization problem is solved. The method is advantaged in that high-precision, rapid, real-time and in-place calibration of an angle encoder can be realized, cost is lower, a two-reading head optimal distribution scheme is suitable for common high-precision test systems, and a three-reading head optimization system can be applied to super-high-precision calibration occasions.

A radio frequency switch circuit with improved harmonic suppression and low insertion loss has an antenna port and a plurality of signal ports. A plurality of transistor switch circuits, are connected to a respective one of the plurality of signal ports and to the antenna port. Each of the transistor switch circuits has a transistor, which in an off state, together with a harmonic suppression capacitor and a parallel inductor both connected thereto, define a tank circuit that suppresses RF signals applied to the corresponding transistor switch circuit from a different one of the transistor switch circuits. The harmonic suppression capacitor is tuned to distribute large signal voltage swings in the RF signal amongst parasitic diodes of the transistor.

In one embodiment, the instant invention can provide an inductor that at least includes the following component(s): at least one FAP positioned along at least one magnetic flux path; where the at least one FAP is a high permeability core gap piece; and where the at least one FAP has an effective magnetic permeability that varies based on at least in part on one of the following factors: i) at least one magnetic flux through the at least one FAP, and ii) sufficient heating of the at least one FAP.

The invention relates to a mixer and method capable of outputting local oscillation harmonic amplitude through cancellation and suppression. According to the mixer and method, a 0-degree power dividing bridge is adopted to perform power division on local oscillation signals from an external local oscillator source, so that two paths of equal-amplitude and in-phase local oscillation signals can be formed, and the two paths of local oscillation signals enter two paths of mixers; the two paths of equal-amplitude and in-phase local oscillation fundamental wave and harmonic signals are converted into two paths of equal-amplitude and anti-phase signals through a 180-degree coupling bridge; and cancellation and suppression are performed on the local oscillation fundamental wave and harmonic signals. With the mixer and method of the invention adopted, the problem of difficult local oscillation fundamental wave and harmonic suppression or incapability of realizing local oscillation fundamental wave and harmonic suppression in a frequency conversion process of a satellite-borne receiver can be solved, and design difficulty of radio frequency links of the receiver can be reduced, and the harmonic and clutter suppression performance of the receiver can be improved. The layout design of all circuits is reasonable, so that the mixer can be adopted as frequency conversion mixers of the satellite-borne receiver and emitter. The mixer has high safety and can be well applied to a satellite-borne communication system.

The invention discloses a rare earth lacking permanent magnet motor zero sequence current suppressing and controlling system and method, which are applied to a motor control field. The method comprises the following steps: using an id=0 closed-loop vector control method for the rotation speed n and the current id and iq to obtain the outputted voltage ud* and uq*; subtracting the given o-axis current i0* from the o-axis i0 to obtain the differential current delta i0 and inputting the delta i0 into a harmonic wave suppressing module which calculates and obtains the zero sequence outputted u0*; inputting the voltage ud* and uq*, the zero sequence outputted u0*, and the rotor position angle theta together into a zero sequence voltage SVPWM module to drive two standard two-level inverters; and connecting the two two-level inverters to the two ends of the windings of the rare earth lacking permanent magnet brushless motor with opened neutral points. With the system and method, it is possible to monitor and give feedback on the zero sequence current in real time and to eliminate the influence of back electromotive force multiple harmonic waves on motor phase current once for all without the need of suppressing the multiple harmonic waves one by one or the need of doing so by more hardware.

A duplexer includes a transmitting filter and a receiving filter which are connected in parallel to an antenna terminal, and a matching circuit connected between the antenna terminal and at least one of the transmitting filter and the receiving filter. A portion of the matching circuit defines a trap circuit for harmonic suppression.

A harmonic mitigating device also functions as a phase converter for supplying single-phase non-linear loads, or as a phase shifting device for three-phase non-linear loads with multiple inputs to create a quasi multi-pulse system. A multiple-winding reactor or a plurality of single-winding reactors, and at least one capacitor, are connected in a crosslink circuit between the reactor windings, or between the reactor windings and another line. At least one reactive element comprising a line winding is connected to each phase or to the neutral and in series with a non-linear load, which provides a high reactance to harmonic currents, and at least one crosslink circuit comprising a second reactive element connected between the second end of the line winding and a capacitor which is connected to any other line in the system.

A space vector pulse width modulation (SVPWM) method for suppressing a common-mode voltage of a multiphase motor includes the following steps: (1) dividing all basic vectors of the multiphase motor into q types, and selecting therefrom x types having equal common-mode voltage magnitude of which an absolute value is smallest; (2) for each type in the x types of basic vectors, structuring y classes of auxiliary vectors according to an optimization model; (3) synthesizing reference vectors by virtue of the auxiliary vectors to obtain functioning time of basic vectors functioning in each switching period; and (4) obtaining an optimal functioning sequence of the basic vectors functioning in each switching period with fewest switching operations of a converter as a purpose. The present invention may effectively suppress a magnitude and frequency of the common-mode voltage of the multiphase motor without increasing calculation complexity or reducing other performance indexes, has a good harmonic suppression effect on a line voltage and a phase current and high steady state and dynamic performance of a torque and a rotating speed, and can be used for a high-performance multiphase power generation system, a multiphase excitation system and a multiphase driving system.

The invention discloses a remote life micro-motion signal detecting method based on a terahertz Doppler radar, and particularly relates to the technical field of life micro-motion signal detection. The method comprises the steps of receiving four living body reflection echo signals in real time by the terahertz Doppler radar, and digitizing the four living body reflection echo signals by a multi-channel digitizer; suppressing static clutters in the four living body reflection echo signals; suppressing linear trend terms in the four static-clutter-free living body reflection echo signals; performing treatment such as complex signal demodulation on the four signals subjected to static clutter filtering and linear trend suppressing respectively, and processing results through set empirical mode decomposition to acquire a reconstructed vital sign signal; performing Fourier transform on the reconstructed vital sign signal to obtain a signal spectrum; suppressing a harmonic component, and taking peaks in the spectrum subjected to in-band harmonic suppression as estimated values of respiratory rate and heart rate respectively.

The invention discloses a harmonic suppression method of a bidirectional converter of an energy accumulation unit in a wind and light accumulation system. The harmonic suppression method comprises the steps of: extracting a quintic harmonic voltage and a septic harmonic voltage and a current of a power grid; then figuring out corresponding voltage compensation quantities of v alpha 5th, v beta 5th, v alpha 7th and v beta 7th; adding voltage quantities v alpha and v beta obtained through decoupling control with a current of an inner ring to obtain output reference quantities V alpha and V beta; and carrying out SVPWM (Space Vector Pulse Width Modulation) on the output reference quantities V alpha and V beta to obtain switching signals of switching on and switching of a controllable switch tube of a three-phase bridge arm of a bidirectional converter. Because the quintic harmonic and the septic harmonic are taken into account in control quantities, the problem of pollution of high-order harmonics due to nonlinear factors of the bidirectional converter is eliminated. The harmonic suppression method is suitable for a harmonic suppression process of the bidirectional converter used by the energy accumulation unit in renewable energy source systems such as the wind and light accumulation system, and can achieve better harmonic suppression effect under the condition of no need of additional hardware input.

The invention provides an impedance matching network. By using a value of a passive device in the impedance matching network, the quality factor of the impedance matching network meets the requirement of harmonic suppression performance indexes and the requirement of impedance matching stability indexes during impedance change. Correspondingly, the invention provides a design method of the impedance matching network. In comprehensive consideration of the impedance change and harmonic suppression performance of a piezoelectric ceramic ultrasonic energy converter, an excellent impedance matching effect can be guaranteed under the operating state when the impedance of a load changes.

The invention provides a software radio receiver circuit. The software radio receiver circuit comprises a low-noise radio-frequency front end circuit, a high-linearity radio frequency front end circuit, a harmonic attenuation radio frequency front end circuit, a common analog intermediate-frequency circuit, a local oscillator signal generation circuit, a biasing circuit and a control circuit. One end of the low-noise radio-frequency front end circuit is connected with the first end of the common analog intermediate-frequency circuit after the low-noise radio-frequency front end circuit is connected with the high-linearity radio frequency front end circuit in parallel. One end of the harmonic attenuation radio frequency front end circuit is connected with the first end of the common analog intermediate-frequency circuit .The local oscillator signal generation circuit is connected with the low-noise radio-frequency front end circuit, the high-linearity radio frequency front end circuit and the harmonic attenuation radio frequency front end circuit. The biasing circuit is used for providing a reference bias voltage and a reference bias current for the software radio receiver circuit. The control circuit is used for controlling work modes of the software radio receiver circuit. The software radio receiver circuit can meet the requirements of various application environments.

The present invention belongs to the technical field of antennae, and discloses a frequency-reconfigurable filter antenna applied to a UWB / WLAN. The frequency-reconfigurable filter antenna applied to the UWB / WLAN comprises: a radiation structure, a feeding structure, a filter structure, a radio frequency control structure, a reflection structure and a dielectric substrate. The present invention can achieve band switching among an ultra wide band state, a 2.4GHz WLAN narrow band state and a 5.8GHz WLAN narrow band state. Due to integrated design of a filter, and by controlling on-off of a diode, the antenna can work under the switched wide band or narrow band state. Moreover, due to an integrated filter function, the narrow band state can achieve good frequency selectivity and high harmonic suppression characteristics.

The invention relates to the technical field of power systems, in particular to a photovoltaic inverter harmonic suppression method based on improved PI+ repetition control. The method comprises the following steps of S1, constructing a PI+ repetition controller model of an LCL type grid-connected photovoltaic inverter; S2, using a zero phase error feedforward compensation method, and adding the harmonic component feedforward control to a PI+ repetition controller. The method can enable the photovoltaic inverter to output high-accuracy harmonic current compensation through the repetition controller while using a PI controller to output a fundamental active power, consider that the repetition controller has the cycle delay and bad dynamic response, and add harmonic component feedforward control to speed up the dynamic response speed of harmonic suppression, thereby achieving the harmonic suppression function.