Studying Non-Eliminated Harmonics in the Current Spectrum of a Three-Level Converter with Programmed PWM

The distortion of voltage generated by the powerful pulse-width modulation converters (PWM) when operating on the low semiconductor module switching frequencies presents a very relevant issue. The Pre-Programmed Pulse Pattern PWM (PPWM) method preventively eliminates or reduces certain converter’s voltage harmonics as well as the current spectrum. This assures that the voltage quality standards are maintained. The paper studies how the primary 50 individual non-eliminated harmonics behave in the voltage spectra of a three-level converter within the modulation index changing range of 0 to 1.15 with a step of 0.01 for six different PPWMs. The study results can be used in PWM algorithms of power converters.