71 results about "Harmonic cancellation" patented technology

A method of seismic surveying using one or more vibrational seismic energy sources activated by sweep signals. The highest order harmonic that has sufficient strength to cause significant harmonic distortion of a sweep segment is determined. A number of sweep segments in excess of the number of sources is selected. Initial phase angles are selected for each sweep segment of each seismic energy source so that substantially all harmonics up to and including the highest order harmonic are suppressed. Using cascaded sweeps, seismic data are acquired and processed to substantially attenuate harmonics upto the selected order.

Methods and systems are provided for reducing torque ripple in an electric motor. A method comprises receiving a torque command and determining a cancellation current command based on the torque command. The method further comprises generating a harmonic cancellation command based on the cancellation current command, wherein the harmonic cancellation command compensates for a phase shift and an attenuation introduced by a current regulated control module coupled to an inverter coupled to the electric motor. The method further comprises providing the harmonic cancellation command to the current regulated control module, wherein the current regulated control module is configured to control the inverter in response to the harmonic cancellation command and the torque command.

Methods and systems are provided for reducing torque ripple in an electric motor. A method comprises receiving a torque command and determining a cancellation current command based on the torque command. The method further comprises generating a harmonic cancellation command based on the cancellation current command, wherein the harmonic cancellation command compensates for a phase shift and an attenuation introduced by a current regulated control module coupled to an inverter coupled to the electric motor. The method further comprises providing the harmonic cancellation command to the current regulated control module, wherein the current regulated control module is configured to control the inverter in response to the harmonic cancellation command and the torque command.

An AC to DC converter with harmonic suppression is provided. The harmonic suppression is provided by forcing an instantaneous current conflict between series connected rectifier bridges 54, 80, such that a voltage waveform at 6 times the AC supply frequency of the AC supply is automatically generated. This waveform is then injected via a injection circuit to give harmonic cancellation.

The present invention discloses a three electric level inverter control system. It contains three electric level voltage source inverter (NPC), field programmable gate array (FPGA), digital signal processor (DSP), wherein FPGA field programmable gate array (FPGA) receiving digital signal processor (DSP) sent control voltage instruction generating three electric level voltage source inverter (NPC) control signal. The present invention also discloses three level inverter control method, featuring 1, digital signal processor (DSP) transmitting space voltage vector amplitude value m and argument for controlling three level inverter triphase reference voltage, 2, field programmable gate array (FPGA) receiving DSP sent space voltage vector amplitude value m and argument, generating signal Vca, Vcb, Vcc, through direct current biasing and dead zone compensation techniques processing to generate three-phase voltage modulation signal Vca **, Vcb **, Vcc **, 3, finally respectively comparing with positive triangular wave, negative triangular wave to generate control pulse. The present invention overcomes the insufficiency of current pulse width modulation method (SVPWM) and special harmonic cancellation method (SHE-PWM), provides a fine rapidity, simple controlling, and practical three level inverter control system and method.

Disclosed is a harmonic cancellation circuit for an RF switch branch having a first transistor with a first gate terminal and a first body terminal, a second transistor having a second gate terminal coupled to the first body terminal, and having a second body terminal coupled to the first gate terminal. Also included is a first resistor coupled between a first coupling node and the second body terminal, and a second resistor coupled between a second coupling node and the first body terminal, wherein the first transistor and second transistor are adapted to generate an inverse phase third harmonic signal relative to a third harmonic signal generated by the RF switch branch, such that the inverse phase third harmonic signal is output through the first resistor and the second resistor to the RF switch branch to reduce the third harmonic signal.

The invention discloses a permanent magnet synchronous motor rotor position observation system for restraining position pulsation observation errors and an observation method of the permanent magnet synchronous motor rotor position observation system, and belongs to the field of motor control. The permanent magnet synchronous motor rotor position observation system for restraining the position pulsation observation errors and the observation method of the permanent magnet synchronous motor rotor position observation system are used for solving the problem that sixth harmonic cannot be effectively reduced through an existing inverter non-linear compensation method and an existing inductance precise modeling method. The permanent magnet synchronous motor rotor position observation system for restraining the position pulsation observation errors comprises a counter electromotive force estimation device, a multi-selection harmonic cancellation device based on a second-order generalized integrator, and an orthogonality phase-locked loop. The observation method of the permanent magnet synchronous motor rotor position observation system comprises the steps of obtaining counter electromotive force estimation information through a model method, carrying out signal processing of a multi-selection harmonic cancellation algorithm based on the second-order generalized integrator, carrying out fifth harmonic detection and compensation and seventh harmonic detection and compensation of counter electromotive force to eliminate the sixth harmonic pulsation errors in a rotor position observation value, and obtaining the rotor position observation value through the orthogonality phase-locked loop. The observation method of the permanent magnet synchronous motor rotor position observation system is a method used for eliminating the sixth rotor pulsation errors, and is applicable to the model method of the medium-and-high-speed sensorless permanent magnet synchronous motor control technology.

A linearity compensation circuit provides cancellation of harmonic distortion introduced by a non-linear system into an input signal by providing a separate harmonic correction component for each harmonic of a fundamental frequency of the input signal. The harmonic correction components are summed with a delayed version of the input signal to produce a corrected input signal for input to the non-linear system. The separate harmonic correction components are generated by respective harmonic correction units, each having a programmable input filter, a Hilbert Transformer filter and a plurality of phase shifters. The output of each programmable input filter is input to the Hilbert Transformer filter and a compensating delay. The output from the Hilbert Transformer filter and the delayed version of the filtered input signal from the compensating delay are input to parallel phase shifters, and the respective outputs from the phase shifters are multiplied together to produce the separate harmonic correction component for each harmonic correction unit.

The invention relates to a method and a system for power supply aging. The method comprises the following steps: firstly, installing a system power supply current sensor CS1 on the input end of a system power supply or installing an aging power supply current sensor CS2 on the input end of an aged power supply to detect the total input current Iin of the system or the input current Ip of the aged power supply; then, transmitting the Ip or Iin to a harmonic current detection unit of an energy-saving electronic load to carry out digital operation so as to operate harmonic content data; transmitting the harmonic content data to a DC / AC control circuit so that the DC / AC control circuit outputs grid-connected current with corresponding harmonic content; and finally, feeding back the grid-connected current Ie to the input end of the aged power supply to carry out higher harmonic cancellation compensation. The energy-saving electronic load saves the aged electricity utilization and also manages the harmonic under the condition that the cost is not basically increased or is less increased, thereby saving the cost of purchasing a large quantity of filters for a power supply plant.

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.

A frequency multiplier circuit is provided that does not rely on filtering to remove unwanted harmonics and spurious content. In one implementation, a frequency doubler comprises a first rectifier doubler stage adapted to receive a first input signal having a first frequency and output a first rectified signal having multiple harmonics; a second rectifier doubler stage adapted to receive a second input signal having the first frequency and offset in phase from the first input signal and to output a second rectified signal, which has the multiple harmonics and is offset in phase from the first rectified signal; and a differential amplifier stage adapted to sum the first and second rectified signals to produce an output signal including a desired output harmonic having a frequency that is double the first frequency. The summing results in the substantial cancellation of unwanted output harmonics in the output signal.

A multi-band receiver includes a first receiver coupled to receive a first desired signal component of an RF signal over a first range of frequencies and generate a first received signal. A second receiver receives a second desired signal component of the RF signal over a second range of frequencies and generates a second received signal. The second receiver includes a harmonic cancellation module that attenuates a harmonic of the first desired signal component that falls within the second range of frequencies.

This invention relates to a device for eliminating harmonic waves and compensating power, in which, a filter is composed of overlapped silicon-steel sheets and copper sheet windings, coils of three copper windings are the same relating to the power and controlled current, the entrance of the windings is connected with the net by switch, after absorbing harmonic waves, the output end of the filter is connected with multiple AC contactors and capacitors by multiple switch sets and the capacitor charges and discharges in terms of 50Hz, namely, harmonic waves are eliminated in the net after the higher-order harmonic waves pass through the filter, current without harmonic waves comes back to the net after being compensated reactively by the capacitor.

The invention relates to a method for solving a specific harmonic cancellation pulse width modulation inverter switching angle. The method comprises the steps of firstly utilizing a trigonometric function duplication formula and a variable substitution for converting a harmonic cancellation equation set into a polynomial equation set, and solving a groebner base of the polynomial equation set; then, sequentially substituting variables into equations for solving the groebner base according to the number of the variables from small to large, and removing real solutions which do not conform to constraint conditions until all the equations are solved; finally, solving an anti-cosine to obtain the switching angle, evaluating the harmonic cancellation effect of the switching angle, and obtaining the globally optimal solution of the switching angel. The method is compared with a current frequently-used numerical algorithm, an initial value is not required to be given, all the real solutions of the harmonic cancellation equation set can be calculated, finally, the globally optimal solution is obtained, and the method has important value for practicality of a specific harmonic cancellation inverter.

The invention discloses a method for achieving an arc suppression coil function by using a high-voltage cascading type SVG. The method includes the steps of 1) monitoring whether a system runs normally or not, 2) when the system runs normally, starting a reactive compensation mode and a harmonic suppression function mode, controlling a cascading type SVG converter to perform system reactive compensation and harmonic cancellation, meanwhile, monitoring bus voltage, judging whether a neutral point of the bus voltage deviates and generates zero-sequence voltage or not, if the neutral point of the bus voltage deviates and generates the zero-sequence voltage, executing the step 3), and otherwise, keeping the current operation state, 3) starting an arc suppression coil function mode, controlling the cascading type SVG converter to compensate ungrounded phase grounding capacitive current, and meanwhile monitoring the bus voltage, judging whether deviation and the zero-sequence voltage of the neutral point of the bus voltage disappear or not, if deviation and the zero-sequence voltage of the neutral point of the bus voltage disappear, executing the step 2), and otherwise keeping the current operation state. The method has the advantages of being simple to achieve and capable of adjusting automatically, having the dual function modes, and being flexible in mode conversion.

The invention discloses an inter-harmonic detection system of a three-phase active power distribution network. The inter-harmonic detection system comprises a three-phase current testing module, a module for transforming three-phase static coordinates to two-phase static coordinates, an inter-harmonic phase-locked loop circuit to be determined, a module for transforming the two-phase static coordinates to two-phase synchronous inter-harmonic frequency rotating coordinates to be determined, a low pass filter, a module for transforming the two-phase synchronous inter-harmonic frequency rotating coordinates to be determined to the two-phase static coordinates, and a module for transforming the two-phase static coordinates to three-phase static coordinates. The inter-harmonic detection system, provided by the invention, is very effective on the inter-harmonic voltage and the inter-harmonic current of a power distribution system. The invention is a system with simple structure, clear conception, and simpler dynamic and static inter-harmonic detection and inter-harmonic cancellation.

The present invention relates to a static var generator possessing a complete APF function. The technical characteristics are that the static var generator possessing the complete APF function comprises an RISC processor, an FPGA module, six DSPs, a SVG inverter, a PWM drive circuit of the SVG inverter, an APF inverter and a PWM drive circuit of the APF inverter; the FPGA module is connected with the RISC processor and the six DSPs separately, and all the six DSPs acquire the current of a power grid via a hall sensor, a signal adjusting circuit and an A / D conversion module, are responsible for the algorithm operation of a SVG function and the APF function and the PWM driving signal output, drive the SVG inverter and the APF inverter to work separately, and are also connected with a synchronization detection circuit and a phase-locked loop circuit separately. In order to compensate a reactive current and a harmonic current accurately and timely, the static var generator possessing the complete APF function obtains a load current reactive signal and a harmonic signal rapidly and accurately in a multi-CPU control manner to generate a corresponding compensation signal to offset the reactive power and harmonic wave in a power supply, thereby achieving the purposes of reactive compensation and harmonic cancellation.

The invention provides an improvement fundamental frequency modulation method for a cascade static synchronous compensator, and relates to the technical field of fundamental frequency modulation for the cascade static synchronous compensator. The method aims to solve the problem that the switching angle acquired by the fundamental frequency modulation of the conventional cascade static synchronous compensator is inaccurate. The method provided by the invention creates transcendental equation according to cascade direct-current-side voltage fluctuation characteristic, so as to acquire a more accurate switching angle; the creating method of the transcendental equation comprises a mathematic model analysis of a single H bridge converter and mathematic model analyses of multi-level cascade converter composed by m H bridge units, introduction of an actual compensating parameter to an alternating current output voltage equation during mathematic model analysis of the single H bridge converter, and the solving of transcendental equation using Newton iteration method. The method provided by the invention has the advantages of good harmonic cancellation effect, large modulation ratio M, and high static synchronous compensator dynamic property; the method can be applied to the cascade static synchronous compensator with stable system voltage.

A novel methodology for automatically linearizing a harmonic radar transmitter—termed Feed-Forward Filter Reflection (FFFR)—is disclosed. The method combines the reflected second harmonic from a filter with the signal passing directly through the filter. The second harmonic from these two paths are combined with equal and opposite amplitudes to reduce the second harmonic beyond filtering alone. This methodology has been experimentally verified at transmit frequencies between 800 and 1000 MHz. Implemented properly, the technique provides greater than 100 dB rejection between 1.6 and 2.0 GHz. Although the tuning has been automated, further optimization is possible. Automated tuning is demonstrated over 400 MHz of bandwidth with a minimum cancellation of 110 dB. One application for the harmonic cancellation is to create a linear radar transmitter for the remote detection of non-linear targets.

The invention discloses a current conversion device with a function of multi-target load control. The current conversion device with the function of multi-target load control comprises two three-phase converters, wherein one three-phase converter is connected to an alternating-current circuit in series through a coupling transformer to serve as a voltage compensation unit, the other three-phase converter is connected to the alternating-current circuit through an inductor to serve as a current compensation unit, and the two three-phase converters are connected to a common direct-current bus through a direct-current capacitor. Due to the fact that the three-phase converters are connected with the side of a system and the side of a load in series / parallel to carry out voltage compensation and current compensation, the function of multi-target load control which can achieve harmonic cancellation, reactive compensation and voltage stabilization can be achieved, quality of electric energy can be effectively improved, and loss of a power grid can be reduced.

Disclosed is a power supply for measuring the line impedance of an underground cable, which includes an input terminal section having a plurality of input terminals, a plurality of autotransformers, a transformer adjustment tap, a plurality of 3rd-harmonics cancellation transformers, and an output terminal section having a plurality of output terminals. The autotransformers are connected respectively to the input terminals. The transformer adjustment tap is connected to all of the autotransformers. The 3rd-harmonics cancellation transformers are connected respectively to the autotransformers. The output terminals are connected respectively to the 3rd-harmonics cancellation transformers. The autotransformers are simultaneously controlled by the transformer adjustment tap so as to uniformly boost the powers supplied respectively to the autotransformers, and 3rd-harmonics of the powers are cancelled in the 3rd-harmonics cancellation transformers to remove noise, so that the powers are stably applied respectively to the phases of the underground cable.

The invention relates to a harmonic identification method, in particular to a harmonic identification method of a sinusoidal vibration test of an electrohydraulic servo vibration table. The method comprises the steps that (1), a state space model of a response signal is established; (2), a state vector estimated value at k time is subjected to recursive calculation; and (3), the state vector estimated value is decomposed, and a harmonic value at the k time is extracted. The harmonic identification method of the sinusoidal vibration test of the electrohydraulic servo vibration table can obtain more accurate information of a harmonic component of the response signal more quickly in real time, so that a data basis is provided for harmonic cancellation directly.

A method and apparatus for cancelling, from signals received by a radio device in a first frequency band, interference generated by the radio device in the first frequency band when the radio device transmits simultaneously radio signals on at least a second frequency band.

Disclosed is a power supply for measuring the line impedance of an underground cable, which includes an input terminal section having a plurality of input terminals, a plurality of autotransformers, a transformer adjustment tap, a plurality of 3rd-harmonics cancellation transformers, and an output terminal section having a plurality of output terminals. The autotransformers are connected respectively to the input terminals. The transformer adjustment tap is connected to all of the autotransformers. The 3rd-harmonics cancellation transformers are connected respectively to the autotransformers. The output terminals are connected respectively to the 3rd-harmonics cancellation transformers. The autotransformers are simultaneously controlled by the transformer adjustment tap so as to uniformly boost the powers supplied respectively to the autotransformers, and 3rd-harmonics of the powers are cancelled in the 3rd-harmonics cancellation transformers to remove noise, so that the powers are stably applied respectively to the phases of the underground cable.

The present invention provides a Seven-phase induction machine harmonic cancellation method based on the SVPWM. In a drive system of a multi-phase motor supplied with power by a voltage source and aninverter, the motor is little in impedance in the generalized zero sequence sub space, a traditional SVPWM is employed to cause a large stator harmonic current. The present invention provides a control method of low output harmonic wave and a low switching loss. According to the space decoupling idea, voltage vector is projected in the harmonic wave sub space to generate a resultant vector while in a fundamental wave sub space, 3 amplitudes and 6 vectors are combined to be the resultant vector, and the vector applying sequence and time are regulated, and three-times and five-times harmonic wave sub space resultant vector is 0 to achieve the effect on harmonic cancellation.

The present invention belongs to the technical field of current detection, and discloses an intelligent active power filter instructional current detection system. The system comprises a voltage collection module, a current collection module, a temperature collection module, a main control module, a detection module, a fault detection module, a fault alarm module and a display module. The method employs the detection module to still accurately detect harmonic waves when the three-phase network voltage is not balance, is good in compensation effect, can properly regulate and control a target according to the compensation requirement, and is more flexible in control mode and high in practicability; the method can regulate and control a target according to different compensation demands in the condition that the network voltage is not balance to achieve complete harmonic cancellation or unit power factor compensation; and moreover, the method employs the fault detection module and the fault alarm module to perform timely detection of fault signals and can notify workers of safeguard procedures.

The invention provides an intelligent combined power capacitor, relating to reactive compensation equipment of a low-voltage distribution network. The intelligent combined power capacitor comprises a shell (1), a touch control panel (3), a micro-electronic measurement and control device, a capacitor combined switching switch with harmonic cancellation, a main power switch, a plurality of wiring ends and a protective cover (2), wherein the touch control panel (3) is arranged at the front end of the shell (1) and faces to the front side surface of the shell (1); the micro-electronic measurement and control device is arranged in the shell (1) and comprises a single chip microcomputer; the capacitor combined switching switch with harmonic cancellation is arranged in the shell (1) and is controlled for switching by the micro-electronic measurement and control device; the main power switch is arranged at the rear end of the shell (1), and a switch handle faces to the top surface of the shell (1); the plurality of wiring ends are arranged at the rear end of the shell (1), and the opening directions of the wiring ends are vertical to the rear side surface of the shell (1); and the protective cover (2) is arranged at the rear end of the shell (1) and is used for preventing accidents caused by that the wiring ends are touched by misoperation or foreign matters enter the wiring ends. In the intelligent combined power capacitor, the use is safe when in switching, the impact current is less, the service life is long, the cost is low, and the installation and the operation are simple and convenient.