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

The invention discloses a vibration isolation device for a floating plate. The vibration isolation device comprises a sleeve (6), a locking backing plate (5), an upper bearing plate (3) and a base (15), wherein the inner wall of the sleeve (6) is provided with a spacing block shoulder (10); the locking backing plate (5) is fixed on the spacing block shoulder (10) through a connecting plate (5a); the locking backing plate (5) is matched with the lower surface of the spacing block shoulder (10); an adjustment backing plate (4) is arranged between the locking backing plate (5) and the upper bearing plate (3); the upper bearing plate (3) is connected with the base (15) through a gland cover (2); and an elastic element (14) is arranged in the gland cover (2). The vibration isolation device disclosed by the invention is concise in structure and convenient in installation, maintenance and disassembly, can be used for solving the problem that the rubber floating plate vibration isolator in the prior art is easy to age and has short service life. In addition, the vibration isolation device disclosed by the invention has good vibration isolation effect.

The invention discloses a current double-loop control method based on repeated PR control for a three-phase LCL grid connected inverter. The method comprises a capacitive current feedback control link and a grid connected current control link. The grid connected current outer loop uses repeated PR regulator control and is used for performing high-performance control on the grid connected current. The capacitive current inner loop uses PI regulator control. The output of an inner loop regulator is modulated by SPWM and then drives the operation of the six IGBT switch tubes of a three-phase inverter bridge. The current double-loop control method achieves high-performance control on the grid connected inverter, suppresses the resonance peak of a LCL grid connected filter, and maintains system stability.

The invention relates to a filter circuit, wherein the performance requirement of the filter circuit for a three-phase converter is that small high frequency harmonic content is output. The circuit comprises wire-incoming inductors (L1, L2 and L3), filter inductors (L4, L5, L6, L7, L8 and L9), filter capacitors (C1, C2, C3, C6, C7, C8, C11, C12 and C13), damping resistors (R1, R2 and R3) and bridge side inductors (L10, L11 and L12). The filter circuit has the advantages that the filter circuit can still filter switching ripples at the position of a switching frequency and switching ripples several times of the switching frequency effectively at lower switching frequency; a single filter branch circuit is arranged, so that for a certain specific time ripple circuit, the absorption effect is better, meanwhile current flowing through the damping resistors can be reduced, loss of the damping resistors is reduced, and system stability is improved; the filter circuit is small in size, cost is reduced, and design space is saved.

The invention relates to a composite vibration isolation device based on particle damping and a memory alloy material. The composite vibration isolation device comprises an elastic part and also comprises a particle damping part and an auxiliary limit vibration isolation part. The particle damping part contains a particle damping chamber, particles and a soft material, and the auxiliary vibration isolation part comprises a memory alloy bar, a laminated plate, rubber and a base plate. The particle damping part can be combined with the auxiliary limit vibration isolation part by virtue of technologies such as welding and bolted connection, and the auxiliary limit vibration isolation part can be connected with the elastic part, a lower base plate and the base plate by virtue of bolts or in a welding manner. By virtue of damping energy dissipation of the particle damping part and hyper-elasticity of the memory alloy bar, the composite vibration isolation device provided by the invention integrates vibration attenuation and energy dissipation into a whole and overcomes the defect that an existing vibration isolator has a poor damping effect when the frequency is lower than 20Hz, and the vibration isolation effect is better enhanced. The composite vibration isolation device provided by the invention is applicable to vibration isolation of a track in the field of track traffic and can be also applied to vibration isolation of equipment foundation or floors of sensitive buildings.

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 a method for stable control of positive damping reconstruction impedance of a high-voltage direct-current power transmission system. When switching frequency of a rectificationstation is relatively high, through introduction of a virtual resistor, system damping within control bandwidth is enhanced, and direct current side oscillation is suppressed. When switching frequency of the rectification station is relatively low, and direct current side oscillation frequency is beyond the control bandwidth, the virtual resistor turns to show negative resistance property, and system stability is deteriorated. Phase correction is performed on negative resistance beyond bandwidth, and amplitude of the virtual resistor is not changed, thereby effectively improving a damping characteristic of the high-voltage direct-current power transmission system, suppressing oscillation of the system direct current side, and improving system stability.

The invention relates to a Z-source inverter grid-connected control method based on single-cycle and double current loop control. LCL is used to filter the grid-connected current, and the grid-connected current loop and capacitor current loop are used for double-loop control, which can effectively suppress The resonance peak of the LCL filter is reduced, and the adverse effect of the resonance peak on the Z-source inverter grid-connected system is reduced. The outer loop of grid-connected current adopts PI controller, and the inner loop of capacitive current adopts P controller, which increases the stability of the system and improves the control accuracy of the system; single-cycle control is used instead of traditional PWM control for Z-source inverter The control of the switch can effectively suppress high-order harmonics; the proposed Z-source inverter grid-connected control scheme with single-cycle control and double current loop control can effectively suppress the influence of the resonance peak value of the LCL filter on system stability. The stability of the system is improved, and the harmonic distortion rate of the grid-connected current is effectively reduced, and the quality of the grid-connected electric energy is greatly improved.

The invention discloses a grid-connected current control method applied to an LCL type rectifying feedback unit. The method comprises a step of converting a network voltage and an AC side current in athree-phase stationary coordinate system into a network voltage and an AC side current in a two-phase stationary coordinate system and obtaining a predicted current by a current prediction link, a step of allowing given active current and reactive current to pass through a transformation matrix to obtain current given values in the two-phase stationary coordinate system, and a step of taking thepredicted current and an error value of the current given values as an input of a new control link, adding an output of the new control link and a voltage of a common coupling point through a feedforward coefficient to obtain loop output signals, obtaining a control output signal under the three-phase stationary coordinate system through the transformation of the transformation matrix, generatinga modulated signal through DC bus voltage decoupling, and obtaining a PWM waveform by a modulator. According to the invention, the gain of a grid-connected current control loop is improved, the resonance peak is effectively suppressed, and the influence of grid voltage disturbance and DC bus voltage fluctuation on the stability of the system is alleviated.

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 invention relates to a floating-raft vibration isolation system with suppressed resonant peaks. The floating-raft vibration isolation system comprises a unit and a raft. A first switch-type damper is arranged between the unit and the raft. A second switch-type damper is arranged between the unit and a base.

According to a single-phase LCL-type grid-connected inverter resonance suppression method based on output-network side current estimation, through utilization of characteristics that an LCL filter is similar to the L-type filter in terms of a low-intermediate frequency band and the frequency characteristic of the L-type filter has no resonance peak, integration is carried out by an output of a controller Gc (s) (the gain of an integrator is a reciprocal of a total inductance value of the LCL filter) to obtain an estimated value of the network side current; at the same time, an observation compensator is introduced and a network side current measurement value is taken as a reference input. The estimated value is corrected and the estimated value is used to track the measurement value to achieve the purpose of filtering the measured value of the network side current. The estimated value is the measurement value of filtering.

The invention belongs to the field of hydraulic vibration and control and in particular relates to a high frequency excitation device and a control system. The high frequency excitation device and thecontrol system disclosed in the present invention can help suppress a resonance peak of the system and improve dynamic response speed. Speed feedback can be used for improving resonance frequency ofa power system, a damping ratio of the system can be increased via the acceleration feedback, and the resonance peak which affects the stability of the system can be reduced. The high frequency excitation device and the control system disclosed in the invention is large in safety factor, self-vibration frequency can be outside a work frequency bandwidth range of the system, and continuous optimization is realized according to analysis results; a valve-controlled cylinder system is integrated with an energy accumulator, a filter and a pressure sensor to enable the system to be compact and simple in structure, and the dynamic response of the system can be improved. Based on the high frequency excitation device and the control system disclosed in the present invention, a nonlinear model thattruly represents system characteristics can be conveniently built, and a hardware device basis is provided for exploring effective control strategies and parameter tuning methods.

The present invention provides a method, device and medium for designing LCL filter parameters based on the damping ratio. Firstly, according to the traditional LCL filter design method, the converter side inductance and filter capacitor parameters are selected; then, using the damping ratio, the damping resistance and The value of the inductance on the output side is optimally designed; in addition, an iterative optimization scheme for the total inductance and resonance frequency is also provided. The present invention preferably adopts the optimum damping ratio of 0.28, which can ensure the stable operation of the converter system with the LCL filter with the minimum damping loss. The present invention has few design iterations, can guarantee the high-frequency attenuation design of the LCL filter is accurate, avoids the stability risk introduced by unreasonable damping design, and ensures that the selection of current control parameters is simple and direct, and is suitable for high output side voltage of the LCL filter. occasions with low frequency components.