A new 24-pulse diode rectifier system for AC motor drives provides clean power utility interface with low kVA components

This paper proposes a 24-pulse diode rectifier system suitable for utility interface of PWM AC motor drive systems with low kVA components. The proposed 24-pulse system employs an autotransformer and two zero sequence blocking transformers (ZSBT) in the DC link and a tapped interphase reactor. Results produce near equal leakage inductance in series with each diode rectifier bridge ensuring equal current sharing and performance improvements. A specially tapped interphase reactor is employed with two additional diodes and is shown to extend the conventional 12-pulse operation to 24-pulse operation from an input current stand point. The voltage across the ZSBT is analyzed and the kVA rating of each component in the proposed system is computed. The 5th, 7th, 11th, 13th, 17th and 19th harmonics are eliminated in the input line current resulting in clean input power. The DC link voltage magnitude generated by the proposed rectifier system is nearly identical to a conventional 6-pulse system. The proposed system is suitable to retrofit applications as well as in new PWM drive systems. Simulation and experimental results from a 208 V, 10 kVA system are shown