Control method for wide input grid-connector inverter

Abstract

The invention discloses a control method for a wide input grid-connector inverter, and belongs to the control method for an inverter. The wide input grid-connector inverter disclosed by the invention comprises an input power supply, a first filter inductor, a second filter inductor, a first switching tube, a second switching tube, a first switching unit, a second switching unit, a third switching unit, a fourth switching unit, a filter circuit and a power grid; the control method for the wide input grid-connector inverter is that: when input power is greater than a peak value of an absolute value of the voltage of the power grid, only a buck working mode exists; when the input power is not greater than the peak value of the absolute value of the voltage of the power grid, the buck working mode and a boost working mode exist. The control method for the wide input grid-connector inverter is applicable to a place with a wide input voltage; the straight-through problem of a power tube of a bridge arm of the conventional bridge type inverter is avoided; the reliability is high; dead time is not required to be set for each switching tube; the quality of the current waveform of the power grid is high; single-stage buck and boost conversion can be realized; the input / output current pulse is small; only three isolated driving power supplies are required; only one switching tube high-frequency switch exists at any time, and the efficiency is high.

Description

technical field [0001] The invention relates to a control method of a grid-connected inverter, in particular to a control method of a wide-input grid-connected inverter. Background technique [0002] With the increasing environmental pollution and the continuous shortage of fossil energy, renewable energy sources such as fuel cells, wind energy, and solar energy have attracted more and more attention due to their advantages of cleanness, safety, pollution-free, and renewable. However, the output of solar cells and fuel cells is DC, while the grid voltage is AC. Therefore, grid-connected inverters become an important part of distributed power generation systems and micro-grids. And because the output voltage range of solar cells and fuel cells is wide, sometimes it is lower than the grid voltage, sometimes it is higher than the grid voltage. Therefore, it cannot be realized by using a traditional single-stage step-down inverter, and it is usually necessary to add a pre-stage ...

AI Technical Summary

Problems solved by technology

However, the above public documents have the following problems: the main circuit needs 4 isolated driving power supplies, and the cost is high; when the input voltage is low, they all work in the buck-boost mode, and the input and output currents fluctuate greatly.

In addition, the above-mentioned grid-connected inverter has three high-frequency switching tubes in any half power frequency cycle, and the switching loss is high, which reduces the efficiency

Images