On re-examining symmetry of two-level selective harmonic elimination PWM: Novel formulations, solutions and performance evaluation

This paper analyzes the half-wave symmetrical two-level SHE-PWM, proposes two formulations of the SHE-PWM waveform with multiple solutions and evaluates the solutions for different cases of eliminated harmonics. Previous work on SHE-PWM focused on algorithms for calculating the solutions and only considered the quarter-wave symmetry in the formulation. In this paper two different formulations to the problem are considered and solutions for a number of eliminated harmonics are presented. The different formulations increase the solution space of the problem and the number of acquired solutions. A comparison of the solutions in terms of harmonic performance is also presented. When compared with the quarter-wave symmetrical solutions, certain half-wave symmetrical solutions exhibit better performance and additional benefits can be acquired for two-level converters operated under SHE-PWM techniques. The HW symmetrical solutions are experimentally verified on a laboratory setup in order to confirm the validity of the solutions sets. (C) 2013 Elsevier B.V. All rights reserved.