Vector optimised harmonic elimination in multilevel inverters/converters - A solution

The main challenge in determining the optimized switching angles in PWM inverter/converter applications is finding solutions to sets of nonlinear equations. It is useful all existing solutions are detected so as only those yielding the best system performance can be selected. Several algorithms have recently been published which allow derivation of solutions, based on specific criteria and smooth DC link voltage. These no longer hold when link capacitor size is reduced. This situation is encountered in systems in which reduction of link capacitor size is a desirable feature, such as in traction and renewable energy systems. Vector optimized harmonic elimination PWM strategy (VOHEPWM) helps to restore the efficiency of optimized harmonic elimination PWM strategy (OHEPWM) but due to DC link voltage ripple more than one solution may exist. In this paper, solution determination is considered in the case of a single-phase multilevel cascaded VSI inverter. The derived results and simulation regarding the studied scheme are presented.