A 36-Pulse Rectifier with a Pulse-Tripling Circuit Based on Auxiliary Cross Windings

To enhance the harmonic suppression capability of traditional 12-pulse rectifiers, this paper presents a 36-pulse rectifier with a pulse-tripling circuit based on auxiliary cross windings (PTC-ACW) at the DC side. The designed PTC-ACW is composed of two capacitors, an auxiliary single-phase transformer, an inter-phase reactor, a single-phase bridge rectifier, and a pair of auxiliary diodes. By analyzing the voltage relationship between its input and output terminals, the circuit operates in multiple conduction states, extending the current modulation of the rectifier from a single to triple mode and effectively improving the input current waveform. The results demonstrate that the proposed configuration increases the input current step number from 12 to 36, reducing the total harmonic distortion (THD) from 11.2% to 3.6%. The proposed PTC-ACW is a purely passive circuit whose equivalent capacity accounts for only 2.45% of the output power. Owing to its compact configuration, easy implementation, high dependability, and low cost, it offers a practical solution. A 1.2kW experimental prototype was developed to validate the analytical results and confirms the effectiveness of the proposed design.