Transformer-free inverter

Abstract

The invention discloses a transformer-free inverter, which comprises an input capacitor, six power switching tubes, six anti-parallel diodes and two filter inductors. The switching motion is performed by using the cooperation of the six power switching tubes and the anti-parallel diodes thereof, and then when the output voltage of the inverter has zero level, the output alternating current side and the input direct current side of the inverter are in a decoupling state so as to ensure that the common mode voltage of the inverter is kept constant when the output voltage of the inverter realizes three-voltage modulation and further fully eliminate the common mode current; the switching voltage on the power switching tubes is changed to be half of the direct current input voltage, so the switching loss of the power switching tubes is reduced; and the output current ripple wave of the inverter is further reduced through frequency doubling pulse width modulation, the output electrical energy quality of the inverter is improved, and the volumes of the filter inductors are reduced so as to reduce the copper loss and magnetic loss generated on the filter inductors.

Description

technical field [0001] The invention relates to an inverter in the field of DC-AC converters of power electronics technology, in particular to a transformerless inverter. Background technique [0002] Inverter refers to a power electronic converter that converts DC power into AC power through the opening and closing of semiconductor power switching devices. Its function is to convert the power quality obtained from batteries, solar cells, fuel cells, etc. The poorer DC raw power is converted into AC power with higher power quality that can meet the voltage and frequency requirements of the user's load. As the world's energy shortage and environmental pollution become increasingly 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 and renewable energy has attracted more and more attention from countries all over the world. . A large number of renewable energy sources a...

AI Technical Summary

Problems solved by technology

[0005] At present, full-bridge inverters and half-bridge inverters with bipolar modulation are generally used to solve the common-mode current problem. However, this type of inverter structure can only achieve two-level modulation of the output voltage, resulting in output current The ripple is large, and the volume of the output filter inductor increases accordingly, so that the quality and efficiency of the inverter power generation cannot be improved. The half-bridge mid-point clamped inverter structure can eliminate the leakage current to the ground and realize the three-dimensional output voltage at the same time. Level modulation, but this structure requires that the DC side input voltage is twice that of the full-bridge inverter, correspondingly increasing the number of DC input sources in series in the previous stage or increasing the boost of the DC / DC boost circuit in the previous stage Proportion and design difficulty.

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