32results about How to "Suppresses the DC component" patented technology

The invention relates to a method for suppressing an output harmonic wave and a direct current component of a single-phase grid-combined photovoltaic inverter. In the invention, an original voltage and current detection device and a digital controller in a photovoltaic grid-combined generation system are utilized, and the controls to the Boost circuit duty ratio and an inverter are increased on the basis of an original control algorithm. A phase current signal output by the inverter is subjected to single-phase conversion, actually output current is compared with a reference value, and a difference value is subjected to PI regulation to obtain a voltage control command of a fundamental wave and a harmonic wave; a direct current component detection value obtained by calculating the phase current signal and a given calibration currents difference value are processed to obtain a direct current component suppression voltage command; and after a control command of instantaneous fundamentalwave voltage, a control command of instantaneous harmonic wave voltage and the direct current component suppression voltage command are added and processed to obtain a control command used for the inverter. The invention realizes the control of the active and reactive current of the inverter, the elimination of the designated harmonic wave and the suppression of the direct current component and can effectively improve the electric energy quality of the grids.

The invention discloses a virtual synchronous generator-based microgrid inverter balance control method. The method comprises steps: capacitive current is estimated according to a general differential discretization equation, and in comparison with the traditional method, the differential discretization features have better amplitude frequency features through reasonable parameter configuration; a combined feedback control method between the output frequency of the microgrid inverter and the grid frequency is adopted, independent adjustment on a power-angle control droop coefficient and a virtual damping coefficient is realized, and the purpose of decoupling control is achieved; a grid frequency logic judgment link with backlash features is given to switch a power outer loop regulator, and mode switching between the grid frequency adjustment and power-limiting operation is realized; and the microgrid inverter is adopted and a weighted control method based on the inductive current and the capacitive current is adopted, the contradiction problem between the dynamic response of the microgrid inverter output voltage and island parallel current-sharing features is balanced, and the overall performance of the microgrid inverter is improved.

The invention discloses a multi-power-supply gridconnected system control method based on a modularized multilevel convertor. The multi-power-supply gridconnected system control method comprises the following steps: the power control part of the modularized multilevel convertor generates a sinusoidal modulation wave; the sinusoidal modulated wave is sequentially subject to direct current supply control, an interphase circumfluence control and a gridconnected current direct current component inhibit control to superpose corresponding regulation value, and is finally subject to carrier wave dephasing SPWM modulation to generate a switch driving signal. The multi-power-supply gridconnected system control method can flexibly control the interphase circumfluence according to the operation state of the multi-power-supply gridconnected system.

The invention discloses a method and system for extracting a positive sequence component and a negative sequence component of a network voltage. According to the method, on the basis that a first phase position voltage ea, a second phase position voltage eb and a third phase position voltage ec in a three-phrase power grid are converted to be a voltage ealpha and a voltage ebeta of a two-phase static coordinate system, as two-stage improper integral processing is carried out on the ealpha and ebeta twice respectively, an alpha-axis positive sequence component V+alpha, a beta-axis positive sequence component V+beta, an alpha-axis negative sequence component V-alpha and a beta-axis negative sequence component V-beta of the network voltage are obtained, wherein all the components do not contain direct current components; based on all the components, the positive sequence component V+alpha beta and the negative sequence component V-alpha beta of the network voltage are calculated, and the final calculated positive sequence component V+alpha beta and the final calculated negative sequence component V-alpha beta of the network voltage do not contain the direct current components of the network voltage. Thus, as the two-stage improper integral processing is carried out on the voltage ealpha and voltage ebeta of the two-phase static coordinate system twice respectively, the direct current components of the network voltage are restrained, the extracted positive sequence component and the extracted negative sequence component of the network voltage do not contain the direct current components, and then grid-connected inverter can be controlled effectively when the network voltage is unbalanced.

This invention puts forward a method and a system for suppressing DC bias of a transformer and a power converter using said method and system, the input end of which is a full bridge structure, its output is a full wave commutation unit, energy is delivered from the input to the output via the transformer. The system includes: 1. a current sampling unit used in collecting the primary DC component of the transformer, 2. a controller connected with a current sampling unit which regulates work of the master circuit power switch element according to current samplings so as to suppress DC bias of the transformer.

The invention relates to a control method for PI (power to loop) resonance of a photovoltaic grid-connected inverter based on switching of CCM (continuous current mode) and DCM (discontinuous current mode). When the absolute value of grid-connected voltage Vo outputted by the photovoltaic inverter is higher than or equal to boundary voltage Vbo, the CCM control method is adopted; when the absolute value of the grid-connected voltage Vo outputted by the photovoltaic inverter is lower than the boundary voltage Vbo, the DCM control method is adopted. Under different working modes, the occupation space ratio of an alternating current small signal is adjusted by a PI resonance controller, so as to obtain the total occupation space ratio. According to the total occupation space ratio, the corresponding PWM (pulse width modulation) wave is generated to control the action of a pre-stage MOS (metal oxide semiconductor) tube, so as to enable the photovoltaic inverter to realize grid-connected output. The control method has the advantages that the harmonics of grid-connected current flowing through a zero point can be effectively eliminated, and the grid-connecting efficiency and grid-connecting quality of the inverter are improved.

The present invention relates to an optical pickup device, an optical disc device, and a focus adjusting method, capable of effectively removing stray light with a simplified arrangement and suppressing a DC component in a tracking error signal. The laser light reflected on the disc is converged on the first direction and the second direction and astigmatism is imparted to the laser light. Propagating directions of four light fluxes are obtained by dividing using two linear lines parallel to the first direction and the second direction and respectively changed into the directions of (Da-Dd). A signal optical area only including the signal light is generated on an optical detector. A sensor pattern is arranged in the area to suppress the infection of the stray light. The correction multiplying power is obtained and for suppressing the DC component of the tracking error signal based on the light quanlity balance of the areas B,C and the about light quanlity of the areas A,D when the laser light is irradiated on a nonorbital testing disc. The tracking error signal is corrected by the correction multiplying power.

A method for converting multi-order run length data includes using quaternary ( d , k ) code with code rate of R = 5/8 bit/code element as run length limited code in order to convert 5 bit source character formed by decimal system user data to be code character formed by 8 multi-order code elements, using 0 , 1 , 2 and 3 as code element and applying d+1=3 to present minimum number of continuous identical code element to be 3 as well as applying k+1=10 to present maximum number of continuous identical code element to be 10. The data converting device used for realizing said method is also disclosed.

The invention belongs to the technical field of distributed power supply and micro-grids and discloses a three-phase four-wire APF (active power filter) control method based on combination of one-cycle control and SVPWM (space vector pulse width modulation). The method comprises steps as follows: a sector where a voltage vector is located is judged, and corresponding two-bridge-arm switches and two-phase current are selected according to signals generated in the sector where the voltage vector is located; direct-current capacitor voltage Vc and reference voltage Vref are subjected to subtracted operation, an obtained result is regulated by PI, phase voltage Vp is obtained, the obtained Vp is integrated and then compared with voltage drop of the selected current on a sampling resistor, a control equation is obtained, and on-off of a switch on a three-phase current bridge arm is controlled; on-off of a switch on a zero-line bridge arm is required to guarantee that an APF works in a three-phase four-wire state; zero-line current independently is subjected to current compensation through one-cycle control. According to the method, a harmonic detection circuit can be omitted, and on-offtimes of the switches and switch loss are reduced.

A modulation method and a demodulation method of a run length limited (RLL) code with improved direct current (DC) rejection. In the modulation method, reception data is modulated with a DC suppression control code group separated from a data modulation conversion code group. The DC suppression control code group makes full use of the code characteristics in the conversion code group, such as the sign of the parameter CSV representing the DC value in the code word and the characteristics of the parameter INV that predicts the DSV transition direction of the next code word, and is compatible with the data modulation conversion code Compared with the group, the generation condition of redundant codeword or the condition of usable codeword is relaxed. Therefore, the number of code words is increased, and the possibility of DC suppression control is further improved.