A New Generalized Step-Down Single-Stage AC/AC Power Converter

Md Shihab Uddin,Md Rabiul Islam,Md Shamim Anower,Shuvra Prokash Biswas,Abbas Z Kouzani,M A Parvez Mahmud

doi:10.3390/su12219181

Abstract

Most traditional AC/AC power converters suffer from power quality problems and multi-stage power conversion losses. The rectifier and inverter-based AC/AC converter topology not only increases multi-stage power conversion losses, but also increases the volume, weight, and cost, and decreases the longevity of the converter due to the DC-link capacitor, line filter and electromagnetic interference (EMI) filter. High-frequency (about 10 kHz) switching advanced pulse width modulation techniques are generally used in order to compensate the power quality problems, which increase the switching losses and introduce the EMI problems. In this paper, a new generalized step-down single-stage line-frequency switching AC/AC power converter topology is proposed. The proposed converter uses line-frequency switching, and does not require any pulse width modulation techniques. The proposed topology offers promising performances in terms of lower order harmonics, total harmonic distortion, the elimination of DC-link capacitors and EMI filters, and switching losses. The circuit was designed and simulated in a MATLAB/Simulink environment. A scaled-down laboratory prototype of the proposed topology was developed in order to validate the feasibility. The experimental and simulation results reveal the feasibility of the proposed generalized step-down single-stage converter topology, and its excellent features.

Highlights

The utility grid generally provides fixed frequency and voltage power to consumers
In order to improve the power quality of the existing AC/AC power converter, the proposed step down AC/AC power converter can be a good solution for different variable frequency applications
The output voltage and current total harmonic distortion (THD) was reduced by 8.64% and 33.23%, respectively, for a 3:1 (m = 3) frequency conversion of the motor load

Summary

Introduction

The utility grid generally provides fixed frequency and voltage power to consumers. some industrial loads—for example, electric traction, induction heating, voltage regulation and controlled rectifier—require variable frequency power supply [1,2]. It cannot perform generalized/multi frequency power conversion; The output voltage waveform suffers from high total harmonic distortion (THD) problem; It adds lower-order harmonic and inter-harmonic contents to the output power for the inductive load. Due to these limitations, industries prefer to use two-stage converters instead of the single-stage AC/AC converter (e.g., the cycloconverter). A new generalized step-down single-stage line frequency switching AC/AC power converter topology is proposed, which significantly reduces the harmonic distortion of the output voltage without using any pulse width modulation techniques in the switching circuit.

Theoretical Background

16.67 Hz region

Result

Findings

Conclusions