Hybrid Harmonic Suppression Method at DC Link of Series-Connected 18-Pulse Rectifier

Abstract

To suppress the harmonics of series-connected 18-pulse rectifier, a hybrid harmonic suppression method is proposed in this paper. According to the structure of the converter and the KVL, the injection voltages are expressed. According to the injection voltages, the relation between the input voltage THD and the injection transformer turn ratio is obtained. Based on the relationship, when the THD of the input voltage researches the lowest value, the optimal injection transformer turn ratio is determined. Testing result shows that after using the proposed reduction method, the input side THD values of the converter are reduced. The capacity of the suppression circuit is only about 2% of the load power. The proposed converter is qualified for the interface between the AC generator and the DC bus of the aircraft electrical system.