39results about How to "Suppression of resonance peaks" patented technology

The invention discloses a network access current control method for a single-phase less container load (LCL) filtering grid-connected inverter and belongs to the field of network access current control of a grid-connected inverter. The method comprises the following steps of: feeding back six voltage and current variables which are easily measured in a single-phase LCL filter to obtain 18 feedbacks through proportion, integration and differential, and selecting a proper feedback combination to configure a characteristic equation of an LCL filter grid-connected inverter system transfer function from a third order to a fourth order so as to guarantee that four poles of the configured characteristic equation can be freely configured; further configuring a fourth-order characteristic equationin a form that two poles serve as conjugate poles at fundamental frequency and two poles serve as conjugate poles at resonant frequency; and finally, comparing to acquire various feedback coefficients in the selected feedback combination. By the method, the high gain of a system open loop transfer function on a forward path is achieved, a resonance peak at a natural resonant frequency is effectively suppressed, and the system has good steady state and dynamic responses.

The present invention relates to a three-phase grid-connected inverter grid-connected current control method, and relates to a three-phase LCL-type grid-connected inverter grid-connected current control method based on an improved repetitive controller, especially to a grid-connected inverter current control method based on an improved repetitive controller. The voltage of a direct current side ofthe inverter is controlled by a voltage regulation outer ring, the output of a direct current IP regulator is taken as a given electric current as shown in the description of a d axis in a two-phaserotating coordinate system; currents as shown in the description are subjected to inverse park transformation to obtain current set values i[Alpha]ref and i[Beta]ref in an [Alpha][Beta] coordinate system; an inner film structure with repetitive control is improved to shorten the delay time to half of the original delay time; the improvement of the repetitive control is that a proportional controller and a repetition controller are connected in parallel to improve the dynamic response capacity of the repetitive control; and a voltage of a power grid is subjected to clark transformation and thenis output after processing through a feed-forward function as output of a feed-forward link of the voltage of the power grid. The grid-connected inverter current control method based on the improvedrepetitive controller shortens the inherent delay time of the repetitive control to achieve rapid and accurate tracking of the set reference current by employing the inverter grid-connected current soas to have better steady accuracy, response speed and robustness.

The invention provides a sand cushion isolation and shock absorption device for a comprehensive pipe gallery and a building method thereof. The sand cushion isolation and shock absorption device has the advantages of simple structure, convenience in construction, low cost of construction, high applicability and convenience in popularization and implementation. The sand cushion isolation and shock absorption device comprises a foundation isolation and shock absorption device and side wall isolation and shock absorption devices. The comprehensive pipe gallery is buried in a stratum and is formed by foundation mats at the bottom, side walls on the two sides and top plates at the top in a surrounded mode. A foundation isolation and shock absorption layer is arranged under the foundation mats of the comprehensive pipe gallery and is formed by packing coarse sand by earthwork cloth, and a rammed 37 lime earth layer is arranged under the foundation isolation and shock absorption layer. Side wall isolation and shock absorption layers are arranged on the earth meeting surfaces of the side walls of the comprehensive pipe gallery and are formed by packing coarse sand by earthwork cloth. The foundation isolation and shock absorption device and the side wall isolation and shock absorption devices surround the three surfaces of the comprehensive pipe gallery except for the top plates, thereby forming an isolation and shock absorption layer.

The invention relates to an inverter grid-connection control method based on fuzzy control and a virtual synchronous generator. The method comprises the following steps: S1, obtaining a phase angle and potential of the virtual synchronous generator based on a virtual synchronous generator technique according to inverter side output voltage, inverter side output current and grid-connection voltage; S2, obtaining reference current of a current loop based on a proportional-integral control voltage feedback loop according to the potential of the virtual synchronous generator obtained in the step S1 and collected filter capacitor voltage; S3, obtaining three-phase modulation wave based on fuzzy control and the proportional-integral control voltage feedback loop according to the reference current of the current loop obtained by the step S2 and collected filter capacitor current; and S4, comparing the three-phase modulation wave with carrier wave to obtain six switching signals and controlling switching-off and switching-on of an inverter. Compared with the prior art, the stable speed of a system is improved under the premise of ensuring system stability, so that the system has better performance.

The invention discloses a universal vertical shock-resistant rigidity-variable damping self-adaptive vibration-isolation shock-isolation device which comprises a large ring steel wire rope loop (6), a large ring upper clamping plate (7), a lower clamping plate (3), a small ring steel wire rope loop (5), a small ring upper clamping plate (4), an upper cover plate (1) and a lower cover plate (2). Steel wires are wound in a certain direction to form multiple strands of stainless steel wire ropes, and then the large ring steel wire rope loop (6) and the small ring steel wire rope loop (5) which are different in diameter are formed by the stainless steel wire ropes. One end of the large ring steel wire rope loop (6) and one end of the small ring steel wire rope loop (5) are fixedly screwed on the upper cover plate (1) through upper clamping plate bolts, and the other end of the large ring steel wire rope loop (6) and the other end of the small ring steel wire rope loop (5) are sequentially fixed onto the lower clamping plate (3) and are screwed on the lower cover plate (2) in a bolt connecting mode. The double-ring-type steel wire rope shock absorber overcomes the defects that a steel wire rope vibration-isolation device in the prior art is high in production cost, prone to fatigue failure, complex to install, fixed in rigidity and the like, the damping of the double-ring-type steel wire rope shock absorber is increased by one time compared with that of a traditional steel wire rope shock absorber, and dynamic loads can be attenuated quickly.

The invention discloses an optimal delay compensation method for active damping of an LCL-type converter. The method includes determining the delay time of a system to acquire an active damping control model; simplifying the active damping control model, and calculating the virtual impedance generated by an inner loop delay to acquire a resonance peak and the reason why the resonance frequency isaffected by the delay; from the perspective of resonance inhibition, determining the optimal compensation method: feedback coefficients plus lead phase compensation; designing a lead compensation device, determining the feedback coefficients, comparing the ideal and the corrected amplitude-frequency response figures, and verifying the optimality to acquire the optimal amplitude-frequency responsefigures. The optimal delay compensation method has the advantages that resonance frequency shifting and resonance peak amplification both caused by the delay during the active damping control can be suppressed, the stability margin of the system is improved, and the attenuation ability of the LCL to high-frequency harmonic waves and the high anti-interference ability to the grid-side impedance fluctuations are guaranteed.

The invention discloses a hybrid state feedback virtual damping control method for an LCL-type active power filter. The method comprises the following steps: a, using two groups of current sensors to collect current is at the position of a PCC and current il on the side of an inverter respectively; b, taking a difference value of current is at the position of the PCC and current il on the side of the inverter as a state variable, after passing through a second-order high-pass filter, feeding back to voltage ui on the side of the inverter; c, using a control strategy of voltage outer ring plus current inner ring by a fundamental wave ring to obtain a fundamental wave ring current control command, and carrying out astatic control on harmonic waves by using a second-order generalized integrator SOGI by a harmonic wave ring to obtain a harmonic ring current control command; and d, taking the sum of the fundamental wave ring current control command obtained in step c and the harmonic ring current control command and a feedback valve obtained through step a as active power filter control signals, and controlling the on-off action of a power device to generate compensating current. According to the method, active damping control of the LCL-type filter is realized by using an original sensor of the SAPF, so that a harmonic peak is inhibited.

The invention discloses an LCL grid-connected inverter indirect current control method based on instruction current compensation, and belongs to the technical field of grid-connected inverter control.According to the control method, direct-current voltage outer loop and grid-connected current inner loop double-closed-loop control is adopted, on the basis of conventional inverter side inductive current feedback and filter capacitor current active damping indirect current control, the instruction current compensation amount is increased, and the purpose of high-precision control over the amplitude and phase of output grid-connected current is achieved; besides, an improved discrete differential operator is adopted to obtain filter capacitor current and grid-connected current feedback quantity so as to compensate calculation delay of state feedback quantity discretization, stability of the system is improved, and meanwhile the purpose of reducing cost of the sensor is achieved. The method is suitable for a new energy grid-connected power generation system, and is a simple and effective implementation mode.

The invention relates to a compound vibration isolating device based on a magnetic material and an oil damping material. The compound vibration isolating device comprises a metal spring and is characterized by further comprising a magnetic part, an oil damping part and other auxiliary parts, wherein the magnetic part comprises an iron magnet, a magnet and support plates; the oil damping part comprises a piston, a hydraulic cylinder, viscous liquid, a liquid filtering plate and an oil seal; other auxiliary parts comprise a baffle, a limiting plate, a bottom plate and the like. A method for forming the compound vibration isolating device based on the magnetic material and the oil damping material comprises the following steps: firstly arranging the magnet on the inner wall of a multifunctional sleeve via the support plates in an adhesion or bolt connection manner; then combining the iron magnet, the metal spring and the oil damping part; and finally clamping a combined part in the multifunctional sleeve via an upper limiting plate and a top plate to form the compound vibration isolating device based on the magnetic material and the oil damping material. Through the combined energy consumption of the magnetic part and the oil damping part, the vibration isolation effect of the low-frequency condition can be greatly improved. The compound vibration isolating device can be widely applied to special vibration reduction road sections with high requirements on vibration reduction and noise reduction of rail transit.

The invention provides a notch filter for a distributed power supply system, and belongs to the field of filters. The input end of the notch filter is connected with an inverter controller, the outputend of the notch filter is connected with an inverter filter, the input end of the inverter controller is connected with a grid-connected inverter, the output end of the inverter filter is connectedwith a grid-connected switch which is used for conducting and closing the distributed power supply system, the output end of the grid-connected switch is connected with a power grid meter, and the notch filter comprises a resonance circuit, the resonance circuit comprises a resistor R1, an inductor L1 connected with the resistor R1 in series, a capacitor C1 connected with the inductor L1 in series, the resistor R1 is connected with the inductor L1 in series, and the inductor L1 is connected with the capacitor C1 in series. The improved notch filter is adopted, the resonance peak of the inverter filter is suppressed, the stability of the distributed power supply system is kept, the distributed power supply system has small steady-state errors and enough stability margin, and the low-frequency-band gain is improved.

The invention relates to an optical scanning device having an improved response characteristic, for use in an apparatus for optically reading or writing information in one or more tracks on a recording medium. The object of the invention is to provide an optical scanning device which, without any electronic compensation means, very largely avoids resonance peaks and has an improved response characteristic. According to the invention, this object is achieved by a retaining plate which supports the objective lens of the scanning device via bearing elements and has at least one cutout, which separates the mounting points, in the surface which holds the bearing elements for the objective lens holder. The field of application of the invention is optical scanning devices having an improved response characteristic for use in equipment for reading or writing information on an optical recording medium, (such as a CD, DVD, a CD or DVD which can be written to, or else a magneto-optical recording medium).