Mixed SVPWM control method used for three-phase grid-connected inverter

Abstract

The invention discloses a mixed SVPWM control method used for a three-phase grid-connected inverter. Based on a three-phase PWM wave controller, control is carried out according to the following three-phase PWM wave: in an alpha beta voltage vector distribution coordinate system, dividing twelve 30-degree sectors, and naming each sector with a number sequentially; defining first, fourth, fifth, eighth, ninth and twelfth sectors as a three-section type modulation sector, and commanding that a reference vector Vref which generates the three-phase PWM wave is synthesized by two basic vectors in the above six sectors; defining second, third, sixth, seventh, tenth and eleventh sectors as a five-section type modulation sector, and commanding that the reference vector Vref which generates the three-phase PWM wave is synthesized by three basic vectors in the above six sectors. According to the invention, without increasing hardware cost, through controlling a pulse width generating mode, power device switching loss can be decreased by 50% based on a present SVPWM control method.

Description

technical field [0001] The invention belongs to the technical field of grid-connected power generation of distributed renewable new energy such as solar energy and wind energy, and specifically relates to a hybrid SVPWM control method for a three-phase grid-connected inverter. Background technique [0002] With the continuous reduction of fossil energy and the severe situation of global warming caused by the use of fossil energy, renewable natural energy such as solar energy and wind energy, which are environmentally friendly and abundant, are more and more popular among people. These renewable new energy sources are converted into direct current through appropriate media (such as solar cells, wind generators, etc.), and then converted into alternating current through a three-phase grid-connected inverter and sent to the three-phase public grid to complete new energy (solar, wind, etc.) Wind energy, etc.) to AC power energy conversion. How to maximize the conversion efficie...

AI Technical Summary

Problems solved by technology

At present, the SVPWM method is widely used, and this method needs to complete two switching switchings for each power device in each switching cycle (defining that the power device is switched from on to off, or from off to on, which is 1 Each switching of the power device will cause a certain power loss

When the switching frequency is low, the switching loss of the power device can be ignored, but the low switching frequency will cause the three-phase voltage or current output waveform to contain more harmonic content, which will affect the sine degree of the waveform and increase the filter circuit. burden and cost

In order to pursue an output voltage or output current with less harmonic content, it is generally necessary to increase the switching frequency, but it will obviously bring about a large switching loss of the power device, resulting in a reduction in the conversion efficiency of the three-phase grid-connected inverter

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