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  • Author: Tõnu Lehtla x
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Intelligent Transformer: Possibilities and Challenges

Intelligent Transformer: Possibilities and Challenges

This paper covers the concept of an intelligent transformer that is a good candidate to replace a conventional low frequency transformer in the microgrids. As the power production and consumption can vary in a wide range, the new substations have to meet many requirements to guarantee reliable energy management in the autonomous networks. Different topologies of intelligent transformers can be used to meet these requirements. Therefore the advantages and disadvantages of the existing topologies were analyzed. The future trends and challenges are also discussed.

Open access
Cooling Methods for High-Power Electronic Systems

Cooling Methods for High-Power Electronic Systems

Thermal management is a crucial step in the design of power electronic applications, especially railroad traction and automotive systems. Mass/size parameters, robustness and reliability of the power electronic system greatly depend on the cooling system type and performance. This paper presents an approximate parameter estimation of the thermal management system required as well as different commercially available cooling solutions. Advantages and drawbacks of different designs ranging from simple passive heatsinks to complex evaporative systems are discussed.

Open access
Analytical and Experimental Investigation of Neutral Point Clamped Quasi-Impedance-Source Inverter

Analytical and Experimental Investigation of Neutral Point Clamped Quasi-Impedance-Source Inverter

In this paper a new modification of a three-level neutral-point-clamped inverter is presented. The proposed topology combines the advantages of the three-level neutral-point-clamped full-bridge inverter with those of the quasi-impedance-source inverter. The neutral-point-clamped quasi-impedance-source inverter is especially suitable for renewable energy sources.

The steady-state analysis of a neutral-point-clamped quasi-impedance-source inverter in the continuous conduction mode is presented. The presented models as well as deduced equations are verified by an experimental prototype.

Open access