Improvement of a Double Connected Diode Rectifier with a Smoothing Capacitor by Using an Interphase Transformer

Abstract

In this paper, a novel method to reduce harmonics involved in ac line currents of a diode rectifier circuit with a smoothing capacitor inside the dc output is proposed. This circuit consists of passive rectifier devices only. It is applied to the conventional double connected diode rectifier, 12-phase rectifier, and is added an auxiliary circuit which is composed of an interphase transformer with a secondary winding and a single-phase diode rectifier. Input voltage waveforms of the proposed circuit are quasi 24-step voltages which correspond to those of the conventional 24-phase rectifier.
In this paper, circuit performances of the proposed method are discussed by analyzing the input voltage waveforms. Then, effects on harmonic reductions can be clarified by theoretical and experimental results, and ratings of system components are investigated.