Abstract
This paper presents a multilevel ac-dc single-phase converter with cascaded transformers and two dc links. The configuration is composed by k cascaded transformers, which isolate the load from the power source, and 2(k + 1) two-level (2L) legs, in which some insulated-gate bipolar transistor (IGBT) legs can be replaced by diode legs if bidirectional operation is not required. The cascaded transformers have different turns ratio characterizing as an asymmetric configuration. In addition, the second dc link is used to increase the number of voltage levels, which results in better input voltage quality. This dc link has a lower voltage and can be a floating capacitor. The proposed configuration is compared with a conventional configuration. Simulation and experimental results are shown to demonstrate the feasibility of the system.

Abstract
This article investigates three families of symmetric single-phase multilevel converters with two dc links for inverter applications. The proposed configurations are based on cascaded cells formed by two-level legs and injection transformers that are connected to a basic cell formed by two half H-bridgeswith shared-legs. Three types of cells are proposed: cellU, composed of three legs and two transformers; cell V, composed of four legs and three transformers; and cellW, composed of six legs and four transformers. The topologies operate in the nonisolated condition (with one less transformer). The generalized system model equations of proposed topologies are discussed. The transformer turns ratios and the dc-link voltages are determined in order to improve the system symmetry and generate the output voltage with low harmonic contents. An unidimensional pulsewidth modulation technique is presented to control the switches of the converters. Harmonic distortion analysis, number of components, rating of the semiconductor devices, power semiconductor losses, IGBTand diode temperature analysis, and transformer ratings are used to compare the proposed configurations with a modular symmetric multilevel inverter formed by three-legmodules cascaded thought injection transformers. The proposed converters present advantages as higher quality of output voltages, and lower semiconductor power losses using the same or lower number of circuit components. Experimental results are shown to demonstrate the feasibility of the systems.

Abstract
This paper presents a unidirectional converter for wind energy conversion systems (WECS) based on six-phase synchronous generators. The proposed configuration uses three two-level three-phase half-controlled converters, nine legs in total, connected in series with the generator stator windings, in an open-end winding configuration (OEW). Half-controlled converters are composed of three controlled switches and three non-controlled switches, reducing the overall cost of the system. The converters operating principles, pulse-width modulation (PWM), and generator control are discussed. Furthermore, the proposed system is compared with conventional configurations concerning harmonic distortion and semiconductor losses. Simulation and experimental results show the validity of the discussed strategies. Finally, it was verified that the proposed system maintains low-distorted currents over the generator stator windings, despite the uncontrolled switches. © 2022 IEEE.

Abstract
The IEEE Power Electronics Society (PELS) Students and Young Professionals (S&YP) committee is a sub-group within PELS membership committee. The PELS S&YP helps students, and recent graduates transition to be young professionals within the larger framework of the IEEE community, and more specifically within PELS. © 2014 IEEE.

Abstract

Abstract
This article investigates the use of a high-frequency link in a topology with two three-leg series-connected single-phase to three-phase ac-dc-ac converters. The paper discusses the system model, pulse width modulation (PWM) technique, control system, and high-frequency link design. The studied topology is compared with the conventional one regarding the operating point specification, and the control system's complexity, among other characteristics. Simulation and experimental results are provided for validation and illustration of converter operations. © 2022 IEEE.