New Research on AC–AC Converters without Intermediate Storage and Their Applications in Power‐Electronic Transformers and AC Drives

Abstract

AC-AC converters (e.g. matrix converters) are mostly semiconductor solutions for applications where intermediate energy storage is eliminated. This paper summarizes the research done and being carried out at the University of Minnesota for applications in motor drives and power-electronic transformers with advanced features. This paper presents a carrier-based modulation method for matrix converters and its application during for both input unbalance and output over-modulation. Various topologies of matrix converter are described for both drives and power-electronic transformers. These topologies have some inherent benefits like common-mode voltage elimination across the bearings of the motor/generator and controllable power factor at the input side. Some of the described technologies require open-ended machines as load and thereby some advantages like enhanced output voltage (1.5 times the output of normal three terminal load) are achieved. 

Dynamic model of direct matrix converter and its experimental validation

“…The general idea and the great potential of this converter have already been discussed by the authors in previous literature . In detail, a combination of two matrix converters and a high‐frequency power electronic transformer between them can replace the bulky transformers throughout the power grid making it more reliable and active because control of the matrix converters is possible . The realization could also be succeeded with one matrix converter but this will not ensure the bidirectional power flow and also the isolation as discussed in .…”

“…One great possibility of the introduction of matrix converters is the replacement of bulk transformers with new compact solid state power electronic transformers. Matrix converters contribute to high‐frequency operation so that a small‐scale transformer is necessary . On the other hand, operating in different line frequency can bring other issues such as resonances and possible hazards for the normal operation.…”

Modeling and control of a cascaded multilevel converter‐based electronic power transformer

“…As a multiple‐functional FACTS (flexible alternating current transmission system) device with the basic functions of the conventional power transformer , electrical power transformer (EPT), also called power electronic transformer (PET) or solid‐state transformer (SST) , has attracted much attention of both academia and industry, as it offers ways to control the routing of electricity and provides flexible methods for interfacing distributed generation with the grid. On one hand, a number of recent investigations have been done on the circuit topology design, mathematical modeling, as well as establishing and control strategy design of EPT . On the other hand, efforts have specifically focused on the applications of EPT in the areas where low‐frequency transformers are dominating, such as solar farms, wind farms, charge stations, and smart grids .…”

The Three-Phase Power Router and Its Operation with Matrix Converter toward Smart-Grid Applications

“…Another emerging technology for power systems is the matrix converter [9], which also has potential in applications with renewable resources and smart-grids [10][11][12] as it can convert energy like a classic transformer but also offers other advantages such as control of bidirectional power flow and better isolation [13,14]. Previous studies have already experimented with a matrix converter [15] and AC conversion [16], and the combination of both in a single apparatus is a natural extension of this research.…”