Virtual space vector modulation method of voltage-type three-level middle-point clamping converter

Abstract

The invention discloses a virtual space vector modulation method of a voltage-type three-level middle-point clamping converter. The virtual space vector modulation method comprises the steps of building a new virtual vector space diagram of a three-level NPC converter; determining whether a reference voltage vector v<ref> is within a first fan section of the new virtual vector space diagram of thethree-level NPC converter or not; judging a triangle where the reference voltage vector v<ref> is located; calculating action time of each virtual vector according to the triangle where the referencevoltage vector v<ref> is located; calculating action of each actual vector according to the action time of each virtual vector; calculating a switch state output sequence corresponding to a vector inthe triangle according to the action time of each actual vector; and controlling a switch state of each switch on the voltage-type three-level middle-point clamping converter according to the switchstate output sequence corresponding to the vector in each triangle so as to complete virtual space vector modulation of the voltage-type three-level middle-point clamping converter. By the modulationmethod, full-modulation degree and full-power factor DC capacitance voltage fluctuation control can be achieved.

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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