Analysis and Control of a Single-Phase-Inverter–Zigzag-Transformer Hybrid Neutral-Current Suppressor in Three-Phase Four-Wire Systems

This paper presents analysis and control of a hybrid filter that can suppress neutral harmonic currents in three-phase four-wire systems not only with harmonic voltage-source loads but also with harmonic current-source loads. The filter voltampere rating is significantly reduced compared to the conventional neutral-current-suppressing methods. The rectifier part of the neutral harmonic suppressor has been removed by controlling the dc capacitor voltage. The experimental results on a 50-kVA prototype validate the proposed control approach.