54 results about "Resonance damping" patented technology

The invention relates to an active damping method of an LCL grid-connected inverter system. The active damping method is realized through the following steps of: setting conjugated zero points or independent zero points to set off conjugated resonance limit points generated by an LCL filter in the grid-connected inverter system or to draw the conjugated resonance limit points to a stable area, and adopting grid-side inductive current to feed back and introduce a state variable in the LCL filter to conduct feedback compensation. By conducting feedback compensation on grid-side inductive voltage, the resonance damping of the LCL filter is controlled, the waveform and the amplitude of grid current of the grid-connected inverter system are controlled and the influence of grid voltage harmonic wave on the grid current can be effectively suppressed. The active damping method is a simple and effective realization method. A realization circuit comprises parallel and series active damping circuits.

Air bubbles may be used to reduce radiated underwater noise. Two modalities of sound attenuation by air bubbles were shown to provide a reduction in radiated sound: bubble acoustic resonance damping and acoustic impedance mismatching. The bubbles used for acoustic resonance damping were manifested using gas-filled containers coupled to a support, and the acoustic impedance mismatching bubbles were created using a cloud of freely-rising bubbles, which were both used to surround an underwater sound source.

Device for damping vibrations of a vibration surface (21) of the frequency tuned resonance damping kind consisting of one or several elastic damping elements (1–4) and a vibration body (5) supported by the damping elements which together are tuned to damp the vibrations of said surface within a selected frequency range. First mutually co-operating form grip organs give a form grip between said damping elements (1–4) and the vibration surface (21) and second mutually co-operating form grip organs give a form grip between the damping elements and the vibration body. The form grip organs in addition have a recess with gripping surfaces (25–30, 33–35) for transferring vibrations.

The invention provides an LCL type grid-connected inverter without resonance damping. The grid-connected inverter comprises an inverter, an LCL filter, a current sensor, a voltage sensor, a current control loop and a switch driving circuit, wherein the LCL filter is used for grid-connected operation of the inverter; the current sensor is used for grid-connected current detection; the voltage sensor is used for grid-connected voltage detection; the current control loop is used for grid-connected operation of the inverter; the inverter is directly connected with the LCL filter and the switch driving circuit; and the current control loop is used for generating a modulation signal, which is required by an inverse switch in operation, and then providing the modulation signal to the switch driving circuit. The invention further provides an integrated design method of the LCL type grid-connected inverter without resonance damping. According to the invention, control performances of an L type grid-connected inverter and the attenuation property of the LCL filter to a high frequency current ripple are effectively synthesized; and the LCL type grid-connected inverter without resonance damping, provided by the invention, has the advantages of simple design process, low cost and easiness for engineering promotion.

A vibration-shock absorbing mechanism that protects an object disposed in a housing includes a shock-absorbing member that is disposed in the housing and absorbs a shock, and a resonance-damping member that is disposed between the object and the shock-absorbing member and dampens a vibration and shock in a predetermined frequency range including a resonant frequency of the object.

The invention discloses a matrix converter comprising a source damping filtering unit. The matrix converter comprises an input power source, an LC input filtering unit, a switch matrix and a microprocessing unit. Currents provided by the input power source are input to a load successively through the LC input filtering unit and the switch matrix, the microprocessing unit, through control over the resonance damping of an LC filter, controls input current waveforms of the LC filter so as to obtain expected output voltages, and according to the expected output voltages, distributes pulses to each switch tube in the switch matrix to control the work state of each switch tube in the switch matrix. The invention also provides a control method of the matrix converter comprising the source damping filtering unit. The dynamic characteristic is improved, the power supply current harmonic wave content can be reduced, a power supply side is enabled to be always close to a unit power factor, and the efficiency of the matrix converter is improved. At the same time, resonance appearing in the LC filter is effectively inhibited, the total harmonic wave distortion rate of power supply currents is reduced, and the influence exerted by the matrix converter on a power network is decreased.

The invention provides a resonance-peak-free hydraulic vibration isolator and a vibration reducing module of the resonance-peak-free hydraulic vibration isolator. The resonance-peak-free hydraulic vibration isolator comprises the vibration reducing module, a damping module and a connecting module. The vibration reducing module comprises a hydraulic limiting vibration reducing device and a main spring. The damping module comprises a waist-drum-shaped damping sleeve, a first damper and a second damper. The connecting module comprises an upper end cover, an upper limiting end cover, a middle cylinder, a lower end cover with a cylindrical protrusion, and a base. According to the resonance-peak-free hydraulic vibration isolator, the implementation structure of the damping module is simple, the structure of the combination between the bi-directional hydraulic vibration reducing device and the double dampers in the damping module can be matched with the waist-drum-shaped damping sleeve to provide stable damping force in the perpendicular direction and the horizontal direction, perpendicular bi-direction limiting can be achieved, a good centering reset effect on transverse vibration is achieved, and the resonance damping effect is good.

The invention discloses a power inductive filtering system and a virtual impedance comprehensive control method therefor. The power inductive filtering system mainly comprises a novel inductive filtering transformer subjected to special design and a filtering branch connected with the novel inductive filtering transformer, wherein the filtering branch comprises a single tuned filter set and harmonic current controlled voltage source inverters connected in series. According to the power inductive filtering system and the virtual impedance comprehensive control method, power grid resonance damping control of the voltage source inverters is organically combined with zero impedance control of filters according to unsolved technical problems in an existing filtering method and existing device manufacturing process difficulties, so that the problem of performance reduction of a passive filtering device caused by impedance parameter change of a power grid system is solved on one hand and the optimization control of a quality factor of the passive filtering device can be realized for reducing the dependence on the level of a device production process on the other hand; and quality factors of the single tuned filters are enabled to meet design requirements, so that the overall filtering characteristics are further improved.

The invention discloses a resonance peak free vibration isolator and a damping module thereof. The resonance peak free vibration isolator comprises a vibration reduction module, the damping module and a connecting module. The vibration reduction module comprises a hollow hexagon bolt with an internal thread, an adjusting gasket, an internal thread sleeve and a main spring. The damping module comprises a drum type damping sleeve, first dampers and second dampers. The connecting module comprises an upper end cover, a lower end cover, a base and a middle cylinder. The lower end cover is provided with a cylinder type bulge. The drum type damping sleeve is fastened in the inner cavity of the vibration isolator through the hollow hexagon bolt and the adjusting gasket. The two ends of the main spring are respectively propped against the internal thread sleeve and the lower end cover with the cylinder type bulge. The damping module is simple in structure, the two dampers of the damping module are matched with the drum type damping sleeve to provide stable vertical and horizontal damping force, a good centering and resetting effect on horizontal vibration is achieved, and the resonance damping effect is strong.

Devices and methods described herein relate to novel and improved speaker assembly designs that optimize audio quality. Embodiments herein can also facilitate the tuning of audio range by linearizing frequency and amplitude. Some speaker assembly embodiments herein can improve the audio output by alternating layers of rigid and porous material, which can facilitate aperiodic resonance damping. Embodiments herein can also provide a constant audio output and improve the audio directional pattern. Moreover, speaker assemblies herein can improve the overall audio output at all frequencies by eliminating internal acoustic cavity resonance. Embodiments herein can also customize the audio output through tunable or adjustable components, such as modifying the flow resistance, density, thickness, or shape of cabinet layers. This can also shape the directional frequency response and adjust the damping or resonance frequency. Additionally, this adjustability allows assembly designs to be tailored to all different types of speakers.

The invention discloses an LCL filterer passive resonance damping circuit and method, and the circuit comprises an LCL filter and an LCR branch circuit. The LCL filter comprises a filter capacitor Cf, and the LCR branch circuit is in parallel connection with the filter capacitor Cf. The LCR branch circuit comprises a damping inductor Lz, a damping capacitor Cz, and a damping resistor Rz, wherein the damping inductor Lz, the damping capacitor Cz and the damping resistor Rz are in series connection. The LCR branch circuit presents pure resistor characteristics at a resonant frequency, provides damping for a system, and inhibits the resonance. A damping unit presents large capacitive reactance characteristics at a power grid fundamental frequency, and a passing current is smaller. The fundamental wave loss of a damping resistor is greatly reduced. The circuit achieves the inhibition of filter resonance under lower power loss, and a parallel installation mode does not change an original filter electrical node, thereby facilitating resonance inhibition change of an existing LCL filter.

A method and components are provided for implementing EMC shielded resonance damping of a printed circuit board. The EMC shielded resonance damping component includes a capacitor and resistor formed in series combination and contained within a shielded enclosure. A pair of coaxial pads is provided for connection to the printed circuit board. The series combination of the capacitor and resistor is connected between a first pad of a pair of coaxial pads and an interior wall of the shielded enclosure. The shielded enclosure provides a return current path to a second pad of the pair of coaxial pads through the series components.

An apparatus (10) comprising: an audio transducer (201) configured to at least one of: generate sound upon receiving an audio signal provided by the apparatus (10); and convert sound into an audio signal to be processed by the apparatus (10); a housing component (301) comprising one or more sound apertures (303) configured to allow the transmission of sound through the one or more sound apertures (303); and an acoustic cavity (203) inside the apparatus (10) being acoustically coupled to the audio transducer (201) using the one or more sound apertures (303) wherein the one or more sound apertures (303) are configured to provide an acoustic damping.

An acid/alkaline hybrid resonance battery device with damping function is formed of a plurality of similar battery cells connected in either series or parallel. Every battery cell includes an acid rechargeable cell unit and an alkaline rechargeable cell unit, which are electrically connected in parallel. The acid rechargeable cell unit includes at least one acid rechargeable cell, and the alkaline rechargeable cell unit includes at least two serially connected alkaline rechargeable cells. The acid rechargeable cell unit has an electric potential and a capacity close to or equal to those of the alkaline rechargeable cell unit, so that a resonance damping effect is produced between the acid rechargeable cell unit and the alkaline rechargeable cell unit.

The invention discloses a grid-connected converter resonance suppression method considering distributed capacitance of a power transmission line, relates to the field of grid-connected converter operation and control in large-scale new energy power generation, and is a grid-connected converter resonance damping technique for suppressing system resonance characteristic deterioration caused by the ground distributed capacitance of the line. The grid-connected converter resonance suppression method is a control method for a grid-connected converter based on forward path additional digital filterdamping, namely a digital filter is added in a conventional control circuit. The digital filter damping link involves a low-pass filter, preferably a third-order low-pass filter; when the cutoff frequency is set low, a high-frequency signal can be attenuated to a large extent, so that the cutoff frequency is 400 Hz to 610 Hz; when the system resonant peak amplitude is offset, the system resonanceis suppressed. The grid-connected converter resonance suppression method is simple in discretization in actual digital control, and greatly reduces the amount of system calculation, additional sensorsare not needed, and additional power loss is not generated; the robustness is strong, and the dynamic response is good.

The invention relates to the technical field of earphone acoustic structures, in particular to an ANC earphone acoustic test system. The system comprises an audio system, a test sound card, a test microphone, a converter and a console; the audio system comprises a test loudspeaker, and the test loudspeaker comprises a simulation front shell and a simulation rear shell; the simulation front shell is provided with a front cavity, the simulation front shell is also provided with a middle cavity, a duct and a leakage hole, the middle cavity is internally provided with a test space for accommodating a tested resonance damping horn box, the inner wall of the middle cavity is provided with an installation hole site, one end of the leakage hole is communicated with the front cavity, and the installation hole site is provided with an elastic flat pressing pipe body which is used for supporting and is communicated with the interior of the resonance damping horn box; and one end of the flat pressing pipe body is inserted into the mounting hole site. The ANC earphone acoustic test system can be used for testing a resonance damping loudspeaker box with a special structure, the tested resonancedamping loudspeaker box is easy to install and replace, and the actual earphone assembly environment of a loudspeaker is simulated.

The invention provides a magnetoresistance element suitable for working at high temperature, including a reference layer, a memory layer and a tunnel barrier layer, the magnetization direction of the reference layer is constant and the magnetic anisotropy is perpendicular to the layer surface; the The magnetization direction of the memory layer is variable and the magnetic anisotropy is perpendicular to the layer surface; the tunnel barrier layer is located between the reference layer and the memory layer and is respectively adjacent to the reference layer and the memory layer; The memory layer includes a first magnetic material layer, a second magnetic material layer and a non-magnetic coupling layer, and the non-magnetic coupling layer is located between the first magnetic material layer and the second magnetic material layer for The magnetization direction coupling of the first magnetic material layer and the second magnetic material layer are consistent. The design of the magnetoresistance element provided by the present invention can improve the magnetic performance of the memory layer magnetic material under high temperature conditions under the premise of taking into account high magnetoresistance ratio, high perpendicular anisotropy and low magnetic resonance damping.