A Single-Phase PWM Current Source Type Converter Coupling with AC Chopper.

Abstract

A current source type converter can easily generate a sinusoidal current in the ac side by employing a PWM strategy. In the converter system for a single-phase supply, however, the dc current is pulsated because the dc output voltage of the converter contains the ac component with twice the ac supply frequency. The dc current pulsation causes the ac current waveform to be distorted. Although the use of the dc reactor with large inductance allows the dc current pulsation to decrease, the size and the weight of the converter equipment including the dc reactor become larger. A two-phase rectification by using two full-bridge converters and a converter system with ac chopper circuit have been proposed for the purpose of elimination of the dc pulsation. In these converters, the number of the switching devices which consist of the circuit can not avoid increasing.To solve such a problem, this paper proposes a novel single-phase current source type converter coupling with ac chopper circuit and the PWM method. In this circuit, two switching devices in the main bridge are used to form the ac chopper bridge with two added devices and a capacitor. This paper gives the experimental and the theoretical waveforms and the steady-state characteristics. The results prove that the smoothing dc current and the sinusoidal ac current are obtained, and the great reduction of the dc inductance can be achieved in the proposed converter.