摘要
This paper investigates the potential of varying DC-link voltages for improving the output quality of grid-connected power converters. Different from the previous studies focusing on different pulse-width modulation (PWM) methods, this paper explores the impact of different DC-link voltages on the output quality of three-phase power converters, based on the most widely used sinusoidal PWM (SPWM) technique. Instead of using total harmonic distortion (THD) as an indicator, flux-linkage ripples analysis is conducted to quantify the output quality and identify the output quality variations caused by different DC-link voltage values. The operation of a grid-connected two-level converter is first experimentally tested with variable DC-link voltage to verify the feasibility of the proposed method. Then, the same approach is extended to a cascaded H-bridge (CHB) converter based static synchronous compensator (STATCOM), and the performance is found to be in high accordance with the analytical results.