Inverter system with cooperative suppression of three-phase common-mode current and switching loss

Abstract

The invention discloses an inverter system in which three-phase common-mode current and switching loss are suppressed cooperatively. The system includes a DC power supply system, a three-phase three-level ANPC inverter circuit, a three-phase current-limiting capacitor, a filter circuit, and a three-phase load. The DC power supply system provides DC voltage. The three-phase three-level ANPC inverter circuit includes an inverter main circuit and two identical support capacitors, and the three-phase current-limiting capacitor includes three identical current-limiting capacitors. The filter circuit includes two different circuit structures and is pulled back to the midpoint of the DC bus, and the three-phase load includes three AC buses. A three-phase common-mode current and switching loss cooperatively suppressed inverter system designed by the present invention uses a small number of auxiliary capacitors and inductances, occupies a small volume, and can cooperatively suppress the three-phase common-mode current and switching losses in a high switching frequency working environment. loss.

Description

technical field [0001] The invention relates to an inverter system for synergistic suppression of three-phase common-mode current and switching loss, belonging to the field of power electronic converters. Background technique [0002] Common-mode parasitic capacitance to ground is common in the inverter system, and the common-mode parasitic capacitance forms a common-mode loop with the ground, which easily generates common-mode current and affects the performance of the inverter. At the same time, in the inverter system, a higher switching frequency can improve the inverter efficiency but will significantly increase the switching loss. These two points are particularly serious in non-isolated photovoltaic inverters. Non-isolated photovoltaic inverters without transformers have attracted great attention due to their advantages of high efficiency and small size. However, due to the lack of transformer isolation, there is a common-mode loop between the photovoltaic system and ...

AI Technical Summary

Problems solved by technology

[0005] 1) The lossless snubber circuit needs to be designed differently according to different switching frequencies and usage conditions, and the lossless snubber circuit uses many devices and has a complex structure;

[0006] 2) For the three-phase full-bridge two-level circuit, it is difficult for the inverter to be directly applied to the three-level circuit;

[0007] 3) The impact of the common-mode current generated by the parasitic capacitance of the inverter to the ground on the inverter performance is not considered

[0009] 1) When the inverter is fully loaded, the current is large, so that the differential common mode inductor gradually produces a saturation effect, resulting in a large current ripple, which affects the inverter performance, and the differential common mode inductor contains an air gap inside, which occupies a large space

[0010] 2) The inverter does not consider the high switching loss caused by high switching frequency;

[0011] 3) The inverter is designed for single-phase inverters, and its design is difficult to directly apply to three-phase inverters

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