Power Spectra of Single-Phase HBML Inverters with a Pseudo-Random Frequency Carrier Technique

This paper describes a pseudo-randomized PWM technique with fixed frequency carrier synthesis as modulation technique for the HBML (H-bridge multi-level) inverters. The proposed method generates a pseudo-random carrier by randomly synthesizing a carrier with fixed frequency and a carrier with opposition phase. To confirm the validity of the proposed method, a 110 v single-phase HBML inverter was implemented and tested. The experimental results show that the output voltage and current harmonics spectra of an inverter have broadening effect of harmonics, as only simple synthesis of fixed frequency carries