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Modulation method of unipolar and intermittent bipolar hybrid system of grid-connected inverter

A modulation method and inverter technology, applied in the direction of AC network circuit, single network parallel feeding arrangement, output power conversion device, etc., can solve problems such as current distortion, reduce grid-connected current THD, and achieve small THD , suppression of low-frequency harmonics and current peaks, good effect of grid-connected current quality

Active Publication Date: 2022-03-25
HEBEI UNIV OF TECH
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Problems solved by technology

[0009] A modulation method for a unipolar and discontinuous bipolar hybrid system of a grid-connected inverter proposed by the present invention aims at the serious current near the zero-crossing point in the current critical continuous grid-connected inverter under the existing unipolar modulation. Distortion problem, suppress the current distortion near the zero crossing point of the grid voltage, and reduce the THD of the grid-connected current

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  • Modulation method of unipolar and intermittent bipolar hybrid system of grid-connected inverter
  • Modulation method of unipolar and intermittent bipolar hybrid system of grid-connected inverter
  • Modulation method of unipolar and intermittent bipolar hybrid system of grid-connected inverter

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Embodiment Construction

[0044] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention.

[0045] In describing the present invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", " The orientation or positional relationship indicated by "outside", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, so as to Specific orientation configurations and operations, therefore, are not to be construed as limitations on the invention.

[0046] A modulation metho...

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Abstract

The invention discloses a modulation method for a unipolar and intermittent bipolar hybrid system of a grid-connected inverter, the topology of the grid-connected inverter is of a full-bridge structure, the grid-connected inverter comprises a direct current input source Udc, four power transistors S1-S4, an inverter side inductor L, a filter capacitor Cf, a filter inductor Lf and a power grid voltage ug, and the modulation method comprises the following steps: the inverter side inductor L, the filter capacitor Cf, the filter inductor Lf and the power grid voltage ug are connected in parallel; the method comprises the following steps: S1, dividing a modulation interval in a whole power frequency period; s2, recalculating a current upper limit iuperd and a current lower limit ilowerd in the intermittent bipolar modulation region; and S3, modulation is carried out in each interval. According to the method, the smooth transition problem between the positive half power frequency period and the negative half power frequency period is solved, and low-frequency harmonics and current spikes near the voltage zero crossing point of the power grid are effectively suppressed.

Description

technical field [0001] The invention relates to the technical field of power electronic conversion, in particular to a modulation method for a unipolar and discontinuous bipolar hybrid system of a grid-connected inverter. Background technique [0002] As an integral part of string inverters and micro inverters, small and medium power inverters have received more and more attention and research. How to improve energy conversion efficiency and power density, prolong life, and reduce cost has become the main research direction of small and medium power inverters. Among them, the inductor current critical continuous grid-connected inverter does not need additional components (switching devices, resonant inductors or capacitors), adopts hysteresis control to ensure that there is a reverse current in each switching cycle, and utilizes the parasitic capacitance of the MOSFET and The body diode can realize ZVS or ZCS, which greatly reduces the switching loss and improves the effici...

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Application Information

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IPC IPC(8): H02M7/5387H02M1/08H02M1/088H02M1/38H02M1/32H02J3/38
CPCH02M7/53871H02M1/083H02M1/088H02M1/38H02M1/32H02J3/381
Inventor 汤雨张崇
Owner HEBEI UNIV OF TECH
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