A virtual space vector modulation method for a voltage-type three-level neutral-point clamped converter

Abstract

The invention discloses a virtual space vector modulation method of a voltage-type three-level midpoint clamp converter, comprising: forming a new virtual vector space diagram of a three-level NPC converter; determining a reference voltage vector v ref Whether it is in the first sector of the new virtual vector space diagram of the three-level NPC converter; judge the reference voltage vector v ref The triangle in which; according to the reference voltage vector v ref Calculate the action time of each virtual vector in the triangle where it is located; calculate the action time of each actual vector according to the action time of each virtual vector; calculate the switch state output sequence corresponding to the vector in each triangle according to the action time of each actual vector; The switch state output sequence of the voltage-type three-level neutral point clamp converter controls the switch state of each switch in each phase, and completes the virtual space vector modulation of the voltage-type three-level neutral point clamp converter. The modulation method can Realize the DC capacitor voltage fluctuation control with full modulation degree and full power factor.

Description

technical field [0001] The invention belongs to the field of power electronics, and relates to a virtual space vector modulation method, in particular to a virtual space vector modulation method of a voltage-type three-level midpoint clamp converter. Background technique [0002] Compared with the traditional two-level converter, the three-level NPC converter has the advantages of high voltage level, large transmission power, small output waveform distortion rate, and low electromagnetic interference, so it is widely used in power quality analysis, DC transmission, superconducting energy storage, new energy power generation and many other occasions. However, the three-level NPC converter has problems of unbalanced DC capacitor voltage and common mode voltage (current). If the wave increases, it will lead to system failure and cause equipment and personal safety problems. [0003] In recent years, many scholars have conducted research on the DC capacitor voltage fluctuation...

AI Technical Summary

Problems solved by technology

In terms of common-mode voltage, some scholars have proposed some corresponding common-mode voltage suppression strategies based on the three-level SPWM strategy and the three-level SVPWM strategy, but none of them can achieve full modulation and full power factor DC capacitor voltage fluctuation control.

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