Single-phase three-level inverter

Abstract

The invention discloses a single-phase three-level inverter, which comprises an input capacitor, six power switches, two freewheel diodes and a single-phase output filter. The inverter performs switch motion by utilizing the six power switches and the two freewheel diodes cooperatively, so that when the output voltage of the inverter is a zero level, an output alternating current (AC) side and aninput direct current (DC) side of the inverter are positioned in a decoupling state; therefore, the output voltage of the inverter realizes three levels, the common-mode voltage of the inverter is a constant, and common-mode current is completely eliminated. The problem of imbalanced capacitor voltage caused by parasitic capacitance of a power switching device is solved in the circuit; therefore,a working mechanism without leakage current cannot be damaged, and the control means is simple; moreover, the circuit and a dead-zone working mechanism are reliable, and the working stability of the circuit is high. Due to the adoption of a unipolar pulse width modulation mode, the output current ripple of the inverter is low, copper loss and magnetic loss on a filtering inductor are low, and thequality of the output electric energy is high.

Description

Technical field [0001] The invention relates to an inverter in the field of power electronic technology DC-AC converters, in particular to a single-phase three-level transformerless inverter. Background technique [0002] With the world's energy shortage and environmental pollution becoming more and more serious, energy and the environment have become one of the most important issues facing mankind in the 21st century. The development and application of clean renewable energy has attracted more and more attention from all countries in the world. . A large number of renewable energy sources are direct current, which needs to be converted into power frequency alternating current through an inverter to be widely used. Therefore, inverter technology plays a vital role in the development and utilization of renewable energy. [0003] Inverter refers to a kind of power electronic converter that converts DC power into AC power through the on and off actions of semiconductor power switchi...

AI Technical Summary

Problems solved by technology

Inverters with power frequency transformers or high frequency transformers can realize the functions of boosting and isolation. However, inverters with power frequency transformers are bulky, heavy, expensive, and inconvenient for system installation; Although the size and weight of the type inverter are greatly reduced, this type of inverter system is often composed of multiple stages, resulting in a complex system structure and reduced system efficiency.

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