Tri-level carrier modulation method

Abstract

The invention discloses a tri-level carrier modulation method. The tri-level carrier modulation method comprises two modes: when the amplitude of a modulated wave in a certain switching period is lower than a specific value, a first mode modulation manner is adopted, the modulated wave is decomposed into a positive modulated wave and a negative modulated wave which are compared with a triangular carrier, and the switching sequence of all power switch tubes in a tri-level NPC converter is finally obtained, so that the minimum pulse width requirement of each power switch tube is met; when the amplitude of the modulated wave in the certain switching period is greater than the specific value, a second mode modulation manner is adopted, the modulated wave is compared with two same-phase laminated carriers, and the switching sequence of all power switch tubes in the tri-level NPC converter is finally obtained, so that the minimum pulse width requirement of each power switch tube is met. Thetri-level carrier modulation method solves the problem of minimum pulse width possibly appearing in tri-level carrier modulation, and simultaneously, no distortion for the average values of output phase voltage and line voltage can be guaranteed.

Description

technical field [0001] The invention belongs to the technical field of frequency converter control and specifically designs a three-level carrier modulation method for solving the minimum pulse width problem. Background technique [0002] With the rapid development of power electronics technology, three-level neutral point clamped (Neutral-point-clamped, NPC) inverters are more and more widely used in large-capacity, medium-high voltage fields such as AC drive, locomotive traction, and wind power generation. , and continue to develop to the low-voltage field. [0003] Power electronic power devices have the limitation of minimum turn-on time and minimum turn-off time, which requires that the pulse width of pulse width modulation output cannot be infinitely narrow. When the pulse width is less than the minimum switching time required by the power device, the device cannot work normally. Therefore, the too narrow pulse must be processed to meet the minimum pulse width requir...

AI Technical Summary

Problems solved by technology

[0004] The present invention proposes a three-level carrier modulation method that solves the problem of the minimum pulse width in order to solve the shortcomings of the above-mentioned prior art. One of them, to ensure that the average value of the output phase voltage will not be distorted while solving the problem of the minimum pulse width, so as to ensure that the average value of the output line voltage will not be distorted

Images