Active neutral point clamped three-level converter and adjustment and control method thereof

Abstract

The invention discloses an active neutral point clamped three-level converter and an adjustment and control method thereof. The converter comprises an inverter bridge, a three-phase LCL filter and a control circuit, the inverter bridge comprises DC bus support capacitors C1 and C2 and three bridge arms which have the same structure and are connected in parallel; each bridge arm is composed of six switching tubes Sx1-Sx6 and diodes which are respectively connected with the switching tubes Sx1-Sx6 in an anti-parallel manner, and x is equal to a, b or c; the control circuit is respectively connected with the AC power grid and the inverter bridge; the control circuit performs phase-locked tracking on the frequency of the AC power grid according to the voltage of the AC power grid detected in real time, calculates and generates an SPWM (sinusoidal pulse width modulation) signal required during grid-connected operation of the converter, and controls the switching action of a corresponding switching tube; the output end of each bridge arm serves as an AC output end xC and is connected to an AC power grid through a three-phase LCL filter. The three-phase LCL filter is used for filtering higher harmonic current caused by switching action. According to the invention, the conduction loss of the switch tube can be balanced, and junction temperature balance can be controlled.

Description

technical field [0001] The invention relates to the technical field of multi-level converters based on DC bus bars, and more specifically relates to an active neutral point clamping type three-level converter and a control method thereof. Background technique [0002] The converter is the hub connecting the DC bus and the AC power grid. The electric energy is converted between DC and constant frequency and constant voltage or frequency modulation and voltage modulation AC to realize four-quadrant operation. Compared with the traditional two-level inverter, the three-level inverter has the advantages of small switching loss and good output waveform quality, and is widely used in distributed voltage occasions such as photovoltaic power generation and wind power generation. Compared with the reactive power generator (SVG), the four-quadrant ANPC three-level converter has a wider degree of freedom in adjusting active and reactive power, a wider application range, and a lower cos...

AI Technical Summary

Problems solved by technology

However, there are many shortcomings in traditional ANPC control, such as inconsistent switching frequency of inner and outer tubes, inconsistent stress, and the limitation of vector modulation bandwidth to achieve high-order harmonic decoupling control.

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