Transformerless topologies for medium voltage converters

Abstract

Medium voltage adjustable speed converters are a trend for high power applications. The products released in the last decade showed maturity of the technology and brought more confidence to use medium voltage converters in industry applications. Besides high power capability, some segments require optimized footprint for the machines installed inside the plant site. This requirement is pushing the development of a branch of new voltage source converters, called Transformerless Voltage Source Converters. These converters bring the possibility to operate the system without phase-shifting transformers in the connection with the power supply. This paper discusses the well-known topologies applied to medium voltage high power converters, their characteristics, requirements and drawbacks. In addition, it is discussed the recent topologies applied to transformerless converters, with their challenges and developments, presenting a general understanding of this new branch of converters. Additionally, it is presented an example of implementation and evaluation of a transformerless topology.