Dual Stage Single-Phase to Multiphase Matrix Converter for Variable Frequency Applications

A single-stage matrix converter (MC) is preferred for the conversion of a single-phase $({1\emptyset })$ supply of fundamental frequency (50 Hz) to the multiphase $({m\emptyset })$ power supply in a limited operating frequency range (5–15 Hz). These converters possess a limitation on account of voltage and current distortions when the converter is used up to fundamental or higher frequency operating loads. To resolve this problem, this letter proposes a dual-stage $1\emptyset \ \text{to}\ m\emptyset $ MC, which ensures improved power quality across the output voltage and current. This converter has a three-leg front-end side rectifier stage (RS) consisting of six numbers of common emitter configured bidirectional power semiconductor switches. A filter circuit is installed in between $1\emptyset $ supply and RS enabling to build positive average dc voltage across the virtual dc link while maintaining the source current profile. The second stage is an inversion stage having a conventional voltage source inverter structure. The proposed dual-stage MC topology is having a simple structure with the ability to convert the $1\emptyset $ supply to any number of desired output phases not only at the lower frequency but also at the fundamental and higher frequency. The practical applicability of the proposed dual-stage MC is validated through experimental results.

I. Introduction

In Conventional two-stage ac–dc–ac converters, single -phase ac voltage is converted to dc voltage through an uncontrolled or controlled rectifier with bulky electrolytic capacitors [1]. The dc voltage across the electrolytic capacitors is converted to ac voltage of the required phase, amplitude, and frequency using a voltage source inverter. Such an ac–dc–ac conversion system has space limitations and life constraints due to the presence of electrolytic capacitors [2].