Design Guideline for PWM Converter Implementing Periodic VSFPWM: A Comprehensive Analysis on the Harmonics Spectrum

With the great emphasis from the international standard-setting community on the so-called supra-harmonics emissions (2-150 kHz), there are increasing research efforts in this noise level identification, measurement, standard setting and mitigation. The periodic variable switching frequency PWM method, which is known as VSFPWM, can reshape the generated output harmonics spectrum of the grid-connected PWM converter, leading to a significantly lower harmonics peaks, thus keeping the harmonics emission strictly below the harmonics emission standards e.g., IEEE519 & IEC-61000 series. This work conducted an insightful analysis on the harmonics spectra generated by the periodic VSFPWM based on newly derived analytical models. Besides, the sinusoidal VSFPWM which is often used in AC/DC PWM converter, is taken as an example of periodic VSFPWM profile to achieve the minimum efforts of AC filtering. Finally, experimental tests are conducted to verify the analysis and the design guideline provided in this paper.