67results about How to "Modulation method is simple" patented technology

The invention discloses a modulation method and product of a terahertz metamaterial and belongs to the field of metamaterials. The method comprises the steps that firstly, a periodic cylindrical air cavity is formed in a substrate of a PDMS material, then a flexible medium PDMS thin film is arranged above the air cavity, and the metamaterial is arranged on the PDMS thin film; then, outside pressure is added, so that the flexible medium PDMS thin film above the air cavity is protruding or sunken, then geometric parameters of the metamaterial on the PDMS thin film are changed, and finally the response to the incident terahertz wave is modulated. The invention further provides the product which achieves the modulation method. The product comprises a metamaterial structure and a PDMS substrate, the metamaterial structure is arranged on the PDMS substrate, the metamaterial comprises the PDMS thin film and a two-dimension periodic array which is arranged on the PDMS thin film, and the periodic cylindrical air cavity is formed in the PDMS substrate. The modulation method is simple and reliable, is easily controlled, and is relatively high in modulation performance of the linearly polarized beam and the circularly polarized light.

The invention discloses a two-way wired/wireless hybrid optical access method and system based on homodyne/heterodyne detection. The two-way wired/wireless hybrid optical access method includes the steps of modulating a digital signal base band on an optical carrier through an I/Q modulator in a junction center, transmitting the digital signal base band to a mixed ONU through a downlink transmission link, providing coherent light vibration of homodyne reception and heterodyne reception by using a tunable laser in the mixed ONU, using the vibration source as the optical carriers of uplink wired/wireless data signals, carrying the wired access uplink signals and the wireless access uplink signals through a base band I/Q modulation method and a single side band modulation method respectively, using the laser as the vibration source in the junction center to carry out coherent reception, and finishing the full-duplex transmissions of the wired/wireless access signals between the junction center and the mixed ONU and the photovoltaic conversion of the wired/wireless access signals based on the homodyne/heterodyne detection. The two-way wired/wireless optical access method enables the flexible selection of mixed ONU access methods to be increased and achieves high-rate data transmission, sending and receiving, and the spectrum efficiency is high.

The invention discloses an H bridge cascaded multilevel inverter based on a phase shift space vector modulation method. The H bridge cascaded multilevel inverter comprises an inverter body and a controller. The controller is used for sending a PWM pulse to a power switch in the inverter body. The inverter body comprises 3n H bridge units, and n is a series stage number of H bridges of each phase. In A, B and C phases, each phase has n H bridges in series connection, and the series connection refers to the series connection of output sides of the n H bridges. One end of H bridge AC ends connected in series is connected to an A, B or C end, and the other end is connected an N point. An input side of each H bridge is connected to DC power supply, and the power switch of the H bridge is driven by PWM pulse. The controller forms a PWM signal based on the phase shift space vector modulation method. The inverter is simple to drive and easy to implement.

The invention discloses an RSSR-based LED indoor positioning method and a system thereof. The method comprises the following steps: 1, arranging at least three groups of LED lamps in different positions of an indoor ceiling, wherein every group of the LED lamps emits an optical signal with identification information; 2, using a photoelectric detector to receive the optical signal of every group of the LED lamps, and respectively recording to the received signal intensities of the three groups of the LED lamps; and 3, calculating the position of the photoelectric detector according to the position information of every group of the LED lamps and the received signal intensity information. The system comprises a receiving device and at least three emitting devices. A plurality of LED lamps are adopted to position, the optical signal intensities of the plurality of LED lamps are measured multiple times, and multi-time measurement can reduce the influence of a single measurement deviation and reduce the position estimation error, so the degree of dependence on environment is low, the complexity of the system is low, and the positioning precision and the stability of the positioning system are improved. The method can be widely applied to various LED indoor positioning systems.

The invention discloses a VIENNA rectifier modulation method, a VIENNA rectifier controller and a VIENNA rectifier control system for amending an injected zero-sequence component. The modulation method comprises the steps of amending instant polarity of a reference voltage according to an input current; computing the zero-sequence component of the amended reference voltage; injecting the zero-sequence component and computing a duty ratio corresponding to the reference voltage; and generating a PWM-driven VIENNA rectifier based on double carriers. The method, controller and system provided by the invention are simple, convenient, efficient and prone to be implemented in a numerical manner, so that the VIENNA rectifier has input and output with high quality, and is efficient, stable in operation, and greatly expanded in application occasions of the VIENNA rectifier.

The invention discloses a novel voltage type multi-level inverter. When the number of input power sources is expanded from n to n+1, the number of power switch tubes is increased from 2n+2 to 2n+4, wherein n is an integer not smaller than 1, similarly hereinafter; and when voltage of the input power sources is the same, the number of output levels changes from 2n+1 to 2n+3, namely when one power source is added, two power switch tubes and two levels are added. Compared with an existing classic multi-level inverter, the novel voltage type multi-level inverter enables the used power switch tubes and isolation driving to be less, a clamping diode and a flying capacitor and the like are not required, part of the power switch tubes are be in a low-frequency working state, on-off times is little, and switching loss is reduced. According to the novel voltage type multi-level inverter, one-dimensional space vector modulation is adopted, a modulation method is simple, the computing speed is quick, redundant vectors are reasonably utilized, quality of electric energy output by the inverter is improved, and the novel inverter meets the technical requirements of renewable energy and new energy power generation and is suitable for multi-input power source occasions.

The invention discloses a fault-tolerant modulation method for co-busbar double-end cascade type five-level inverters. The method includes the steps that a stator winding of a motor is opened, the two ends of the stator winding are powered up by the two inverters which are completely the same, the two inverters share one set of direct-current busbar, and accordingly the co-busbar double-end cascade type five-level topology is formed; in order to ensure that the reference voltage vector track of each inverter is a circle, when short-circuit trouble happens to a switching device, the maximum output voltage of the inverter is lowered to be half of the voltage before, and only the inside hexagon available switching state is used for synthesizing the reference voltage vector; through rotation and per-unit treatment of a coordinate system, the five-level modulation method is effectively simplified, and the hardware requirement for system control is reduced; by the adoption of equilibrium factors, midpoint potential balance is achieved on the premise that fault-tolerant control is guaranteed. Based on the high-fault-tolerant characteristic of the double-end cascade type five-level inverters, when the switching device breaks down, fault-tolerant operation of the inverters is achieved by reselecting the voltage vector. An optimized 60-degree modulation method is provided according to the double-end cascade type system.

The invention relates to a voltage switching instruction based decoupling-coupling SVM demodulation method of a matrix converter. A bidirectional controllable switch circuit is decomposed to a one-way controllable switch circuit by means of a decoupling-coupling idea, and thus, the matrix converter can be decomposed to a positive group of general voltage type converters and a negative group of general voltage type converters; and with the adoption of a voltage type six-section space vector method, appropriate coupling logic synthesis is performed on the obtained SVM signal and a voltage positive-negative switching instruction signal to obtain flexible and independent control on the bidirectional switch of the matrix converter, thus, a three-phase voltage type non-isolation matrix rectifier achieves functions of AC input and DC output by a simple control logic, and the matrix converter can have functions of positive DC output and negative DC output. The method has the advantages that the control method is simple, the positive DC output voltage polarity and the negative DC output voltage polarity of the matrix rectifier can be achieved, the adaptability to a load is high, the DC voltage utilization rate is improved, the bidirectional flow of switching frequency energy is reduced, and a compact structure and high efficiency are achieved.

The invention discloses a circulating current inhibition method of a parallel operation converter, and aims at solving the problem of high-frequency circulating current, caused by inconsistent modulated carrier waves, of a plurality of converter units. According to the method, grid-connected current of the converter units is detected in real time to obtain variable quantity of the high-frequency circulating current within a half switching period, thereby determining relative positions of the carrier waves of the converter units. The high-frequency circulating current of a parallel system is effectively inhibited by inserting a synchronization period, adjusting a carrier wave frequency and achieving resynchronization of the modulated carrier waves. The method disclosed by the invention has the advantages of being simple and practical, convenient to control, fast in dynamic response and the like.

The invention discloses a power electronic transformer control method based on hybrid pulse width modulation (HPWM). The method includes a CHB input-stage circuit control method and an IBDC output-stage circuit control method. According to the invention, HPWM is applied to cascaded power electronic transformers, and back-stage IBDC is used to control the intermediate DC voltage, an input-stage cascaded H-bridge rectifier only carries out simple power equalization, so as to simplify the control complexity. In order to solve the power equalization problem, the invention provides a switch-mode loop algorithm. With the algorithm, the opportunities of each module to participate in different switch modes are equal in the loop period, and the power is evenly distributed in a certain period of time; with the loop strategy, the HPWM modulation algorithm can be simplified, judging the current direction is not required, and the switch mode of each module can be determined only with the voltage instructions.

The invention discloses an Alpha'-Beta' coordinate-based space vector modulation method of a star-shaped cascaded inverter. The basic vector is greatly increased with increasing of cascaded units according to a space vector modulation algorithm, and the problems of a large amount of redundant switch state vectors, very complicated selection of switch state vectors and calculation of action time and the like exist. On the basis of an Alpha'-Beta' coordinate system, a horizontal coordinate, a vertical coordinate and the sum of the horizontal coordinate and the vertical coordinate of a basic vector of the star-connected cascaded multilevel inverter are respectively corresponding to three linear voltage vectors of a three-phase inverter, and phase voltages of 2n H-bridge cascaded inverters aredirectly controlled by employing linear voltage signals output from n H-bridge cascaded inverters according to a relation between a phase voltage and a linear voltage of the star-connected three-phase inverter. By the method, the switch state signal of each phase corresponding to the basic vector is not needed to be calculated, a large amount of redundant switch state vectors are not needed to becalculated, and the space vector modulation method of the cascaded multilevel inverter is greatly simplified.

The invention discloses a modulation method for spin waves in a self-bias magnetic oscillator waveguide, which is used for modulation a propagation behavior of the spin waves in the waveguide, wherein the propagation behavior comprises the maximum propagation frequency, the cut-off frequency and the propagation path of the spin waves. The modulation method comprises the steps of adjusting the maximum propagation frequency at which the spin waves can be constrained in a middle channel of the waveguide; adjusting the cut-off frequency of the spin waves in channels at two sides of the waveguide; and adjusting the propagation path of the spin waves. According to the invention, modulation can be performed on the propagation behavior of the spin waves on the switched elastic magnetic structure based magnetic oscillator waveguide.

The invention discloses an alpine-pastoral-area alfalfa spiral-type hay bundle processing technology in a severe cold pasturing area, which comprises the following steps of: (1) selection of variety; (2) harvesting; (3) forming the spiral type; (4) airing; and (5) storage. The alfalfa spiral-type hay bundle processing technology has the advantages of long pasture storage time, low requirement in water content, simplicity and easiness in operation and completeness in protein reservation.

The invention discloses a single-phase current-type high-frequency chain matrix power electronic transformer topology and a modulation method thereof. The topology comprises a power network, a front-stage matrix converter, a high-frequency transformer, a post-stage matrix converter, an output filter and a load which are sequentially connected. The high-frequency transformer is used for magnetic coupling and power transferring, and the conversion of an output voltage and a frequency is achieved by the current-type circuit topology. In order that a bidirectional switch of the matrix converter reasonably works, a decoupling modulation strategy of which integral monopole frequency multiplication of the transformer front-stage circuit and the post-stage circuit are discretely combined is proposed; the front stage employs an integral control mode to achieve safety conversion of the matrix converter, and a voltage peak generated by leakage inductance of the transformer is effectively prevented; and the post stage employs a discrete control mode to reduce the switch action frequency, the switch loss of the device is reduced, the system efficiency is improved, and detail mode analysis is performed on a modulation principle and a working condition of a main circuit.

The invention provides a modulation method for improving the current stress of a quasi-Z-source inverter switching device, and the modulation method comprises the steps: subtracting the maximum valueof saddle waves from saddle waves of a conventional voltage space vector modulation SVPWM with the phase difference of 120 degrees to obtain three modulating waves, wherein the maximum value of three-phase saddle waves is a straight line according to the converted waveform, and translating the straight line upwards for M/2, wherein M is the distance between the maximum value and the minimum valueof the modulated wave after the modulated wave and the triangular carrier wave are subjected to per-unit processing between 0 and 1. According to the modulation method, the gate-level signal generation process is simple, the switching loss is low, no low-frequency alternating-current component exists on the input direct-current side, the current stress of the switching device is greatly reduced, and the service life of the switching device is prolonged.

The invention provides an audio-frequency playback system of a parametric acoustic array, which comprises carrier waves for transferring signals and an ultrasonic transducer array for switching the signals, wherein the ultrasonic transducer array is provided with multiple ultrasonic transducers; the ultrasonic transducers are arranged in multiple groups; each group of ultrasonic transducers are provided with different central frequencies; and the central frequencies are larger than or equal to the frequency of the carrier waves or the central frequencies are less than or equal to the frequency of the carrier waves. The invention also provides a modulating method based on the audio-frequency playback system of a parametric acoustic array provided by the invention. Compared with the correlation art, the audio-frequency playback system of a parametric acoustic array provided by the invention is simple to modulate and implement and can obtain ultrasonic waves with low harmonic distortion.

The present invention discloses a non-isolated type three-phase three-level photovoltaic inverter modulation method. The modulation method can effectively inhibit leakage currents of two types of NPIC inverters provided by the present invention. The technical scheme adopted by the modulation method has the key points of: firstly, performing subtraction on any two of modulation signals (reference to the specification) of the NPIC inverters to obtain modulation signals (reference to the specification); then respectively multiplying the modulation signals by a coefficient K to obtain modulation signals (reference to the specification); performing zero-sequence component calculation by (reference to the specification) to obtain zero-sequence signals v0; respectively adding (reference to the specification) and the zero-sequence signals v0 to obtain modulation signals (reference to the specification); and comparing modulation signals (reference to the specification) with a triangular carrier wave VC by means of a comparator to obtain logical signals X,Y,Z; and performing a logical operation provided by the present invention on the X,Y,Z to obtain a logical expression of a switching signal. The modulation method provided by the present invention has the beneficial effects that the switching signal is generated by means of the logical operation, and the implementation manner is simple. The method solves the problem of excessive complexity for implementation of conventional multi-carrier wave modulation and spatial vector modulation, also ensures a constant common-mode voltage of a system, and effectively suppress the leakage currents.

The invention discloses three-phase single-phase high-frequency link matrix PET topology and modulation, which belong to the technical field of power electronic power converter topology and modulation. The topology is formed by connecting a three-phase alternating current power supply, an input L filter, a pre-stage matrix converter, a high-frequency transformer, a backward-stage matrix converter,an output LfCf filter and a load. Magnetic coupling and power transmission are performed by adopting a high-frequency transformer, conversion of output voltage and frequency is realized by using a voltage type circuit topology, and a decoupling modulation strategy of combining discrete SVPWM of a pre-stage circuit and discrete SPWM of a post-stage circuit of the transformer in a double-frequencyphase locking mode is adopted, so that a bidirectional switch of the matrix converter reasonably works. Safe current conversion of the matrix converter is realized by adopting a discrete control modeas a whole, and voltage spikes generated by existence of leakage inductance of the transformer are effectively suppressed.