Cascaded H-bridge inverter SHEPWM method based on NR-ACA algorithm

Abstract

The invention discloses a cascaded H-bridge inverter SHEPWM method based on an NR-ACA algorithm, and the method comprises the steps: carrying out the Fourier series expansion of a cascaded output voltage expression, and obtaining a harmonic amplitude expression. According to harmonic waves to be eliminated, enabling a corresponding harmonic wave amplitude expression to be 0 so as to establish a nonlinear equation set; converting the nonlinear equation set into a single-target optimization problem by using an ant colony algorithm; the switching angle obtained by the ant colony algorithm is used as an initial value of the switching angle of a Newton iteration method, and a high-precision switching angle is calculated; and the switching angle calculated by the algorithm is used for generating a driving pulse of the cascaded H bridge. According to the method, the calculated amount is reduced to a great extent, the convergence speed is improved, the calculated switching angle is more accurate than that of a single intelligent algorithm, the selected harmonic waves are basically completely eliminated, the switching loss is reduced to a great extent, and the method is more easily applied to engineering.

Description

technical field [0001] The invention belongs to the technical field of power electronics, in particular to a cascaded H-bridge inverter SHEPWM method based on an NR-ACA algorithm. Background technique [0002] Cascaded H-bridge multilevel inverters have been widely used because of the same unit structure, easy modularization and expansion, and voltage redundancy. In order to obtain better output waveform quality and reduce harmonic content, SHEPWM technology is born. Specific Harmonic Elimination Pulse Width Modulation technology, also known as Selective Harmonic Elimination (SHEPWM), can effectively eliminate selected low-order harmonics while ensuring the desired fundamental voltage output by calculating the optimal switching angle. [0003] The SHEPWM technology of the traditional cascaded multi-level inverter is only suitable for the situation that the DC side power supply of each unit is completely equal, but in practical applications, the power supply voltage may have...

AI Technical Summary

Problems solved by technology

Although the traditional Newton iterative method has high solution accuracy, if the initial value is not selected properly, the solution speed will decrease or even fail to converge.

In recent years, although scholars at home and abroad have proposed intelligent algorithms to solve the established nonlinear equations, there is a common problem in intelligent algorithms that the accuracy is not high due to the randomness of the search.

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