Voltage-Balancing Control of a Three-Level PWM Converter in a Transformerless Hybrid Active Filter

Abstract

This paper focuses on voltage-balancing control suitable for a three-level diode-clamped PWM converter used in a hybrid active filter. A three-phase downscaled system including a 400-V, 15-kW three-phase diode rectifier with a capacitive load as a harmonic-producing load is designed, constructed, and tested to verify the filtering performance of the hybrid filter and the voltage-balancing control performance of the three-level PWM converter. Experimental results, along with theoretical analysis, verify that the voltage-balancing control proposed in this paper works properly in all the operating regions from full-load to no-load conditions.