Jonatan Rafael Rakoski Zientarski

Simplified Zero-Voltage-Transition Circuits Applied to Bidirectional Poles: Concept and Synthesis Methodology

This paper proposes the concept and the synthesis methodology of simplified zero-voltage-transition (ZVT) circuits applied to bidirectional pulsewidth modulation poles. The main goal of simplified ZVT circuits is to make possible the use of conventional modulation schemes to accomplish better converter performance and to eliminate the synchronous-switching requirements imposed by ZVT integrated multipole topologies. To derive the simplified ZVT circuits, a synthesis methodology is proposed based on the generalization of the ZVT technique, where the restrictions to achieve the zero-voltage switching for the main converter switches are identified. Thereafter, a set of simplified semiconductor switches composed by only one high-frequency switch is defined to be used in the simplified ZVT auxiliary circuits. Thus, using the proposed synthesis methodology, any simplified ZVT topology can be derived, whether or not they have appeared in a previous publication. In order to validate the proposed approach, experimental results for a three-phase ZVT inverter, employing the minimum-loss space vector modulation and operating at 1.5 kW and 20 kHz are presented. The prototype presented an efficiency of 98% at full load representing an improvement of 0.5% when compared to its hard-switched counterpart and 1.8% when compared to an integrated ZVT topology.

Implementation of a stand-alone photovoltaic system based on decentralized dc-dc converters

This paper presents an alternative for standalone PV systems that performs a decentralized input energy processing with maximum power point tracking and a bidirectional converter to manage the power flux control of the battery bank. Previous works demonstrate that the gain in efficiency can reach up to 16% in situations where one or more photovoltaic panels are shaded, damaged or aged. Simulation analyses and experimental results are provided to demonstrate the prospects of the proposed system.

A design methodology for optimizing the volume in single-layer inductors applied to PFC boost converters

In this paper is presented a design methodology for inductor in single-phase PFC boost converters operating in continuous conduction mode (CCM). The methodology is based on a simulation tool that performs an automatic selection of magnetic core taking into account the standard limits for conducted electromagnetic interference (EMI), single-layer winding pattern, and a limit for temperature rise on the inductor. Through a sweep simulation, the algorithm selects the switching frequency and the input current ripple that minimize the magnetic volume in Sendust, molypermalloy or high-flux powder cores. Also, an analysis of the use of single- or multilayer inductors is presented. The design methodology based on the models described in this paper is confirmed by experimental results obtained from a 650 W universal line input PFC prototype, considering a switching frequency of 70 kHz and an input current ripple of 40%.

Understanding the partial power processing concept: A case-study of buck-boost dc/dc series regulator

This paper discusses about the partial power processing concept applied to DC/DC converters, which has been presented in the literature as an option to be used on voltage regulators in several applications such as photovoltaic systems. The purpose of this paper is to elucidate the partial power processing concept and demonstrate that, opposing the sense created in the literature, the fact that a converter performs partial active power processing does not necessarily means that their efficiency and/or power density will be higher than that of a standard converter that processes full active power. It is shown that the performance of DC/DC converter depends not only on its active power, but also on nonactive power that flows inside the converter and the nonactive power drained from source and/or supplied to the load. To demonstrate it, the nonactive power is evaluated on a partial active power buck-boost converter and a new approach is proposed to quantify the total power handled by a DC/DC power converter. Experimental results are presented in order to confirm the analysis.

Simplified zero-voltage-transition circuits applied to bidirectional poles: Concept and synthesis methodology

In order to eliminate the synchronous-switching requirements imposed by zero-voltage-transition (ZVT) integrated multipole topologies, this paper proposes the concept and the synthesis methodology of simplified ZVT circuits applied to bidirectional poles. The main goal of these circuits is to make possible the use of conventional modulation schemes. With the proposed synthesis methodology, new ZVT topologies can be synthesized, as well as the already known ZVT topologies. In order to validate the proposed approach, experimental results for a three phase ZVT inverter operating at 1.5 kW and 20 kHz are presented and some conclusions are stated.

Comparative analysis between integrated and simplified ZVT topologies for three-phase inverters

This paper presents a comparison between the integration and simplification principles of zero-voltage-transition (ZVT) circuits applied to three-phase inverters. Initially, both approaches are defined, and their advantages and limitations are identified. Thereafter, a comparison is made between two selected topologies, taking into account their modulation strategies, the resulting losses in the main circuit, and the harmonic content of the voltage synthesized by the converter. Finally, experimental results for the selected topologies operating at 1.5 kW and 20 kHz are presented in order to validate the proposed methodology.