Effects of eddy currents in transformer windings

Abstract: This article proposes a novel triple-port solid-state transformer (SST) topology based on a hybrid isolated modular multilevel converter (MMC), which overcomes the limitation of voltage ratio R(pu) in the conventional MMC-based SST. By integrating a high-frequency link into the MMC structure and applying various types of isolated submodule (ISM), the proposed SST can function as a step-down rectifier, where UMVDC < UMVAC(p-p). In this case, the power electronics converters used to connect downstream medium-voltage direct current (MVdc) link and distributed energy resources or battery storage require fewer active devices and may minimize the cost of protection equipment. In addition, the proposed SST retains the significant advantages of single-stage SSTs, such as single-stage power conversion, saving capacitor, and a simple control system. First, the topology and modulation strategy of two types of ISMs are discussed. In addition, this article provides a detailed analysis of operation principles, power flow, grid-tied control, and system reliability. Moreover, the proposed converter is compared with other SST topologies in terms of key performance indicators, such as peak efficiency, system volume, and number of active semiconductor devices. Finally, a 300-V/20-kW scaled-down prototype is developed, and the experimental results demonstrate the performance and verify the correctness of the proposed converter.

TL;DR: In this article, the authors developed a high frequency planar transformer model and compared the results of FEM simulation results and simulation model with a comparative study between FEM results and the simulation model and found excellent agreement.

TL;DR: In this article, the authors predicted the optimum notch radius for a specific inductor design using a calorimetric experiment and verified the predicted results with a specific design of a planar inductor.

TL;DR: In this article, a finite element analysis method is used to build the transformer simulation model considering the correction coefficients of the high-frequency square wave, and the temperature distribution with varied frequency is shown.

TL;DR: In this article, the authors discuss the more important causes of eddy currents in heavy conductors carrying alternating currents and surrounded on three sides by iron, and propose a method to identify the most important causes.

TL;DR: In this article, it is shown that a considerable proportion of the effective resistance of inductive coils when used at radio frequencies is caused by the eddy-currents set up in the wires of the coils by the alternating magnetic field in which they are situated, and that in extreme cases the alternating current resistance may amount to more than one hundred times the direct current resistance.

TL;DR: In this article, the authors show how hyperbolic functions of complex angles may be applied to the solution of the problem of heat losses in rectangular conductors that are embedded in open slots.