Abstract
This paper highlights the proposed silicon field-effect transistor (Si-FET)-based high switching frequency three-level (TL) LLC resonant converter. It provides a detailed operational analysis of the converter; the multilevel (ML) organization of cells; voltage-balancing principles; current-balancing principles; loss comparison between Si-FETs and gallium-nitride (GaN)-FETs; and an optimal design consideration based on loss analysis. This analysis reveals that the switching losses of all power switches can be considerably reduced as the voltage across each switch can be set to half of the input voltage without an additional circuit or control strategy. Moreover, the current of each resonant inductor is automatically balanced by a proposed integrated magnetic (IM)-coupled inductor. Therefore, the operating frequency can be easily increased to near 1 MHz without applying high-performance switches. In addition, the resonant tanks of the converter can be a group of cells for multilevel operation, which indicates that the voltage across each switch is further reduced as more cells are added. Based on the results of the analysis, an optimal design consideration according to the resonant tank and switching frequency is discussed. The proposed converter was validated via a prototype converter with an input of 390 V, an output of 19.5 V/18 A, and a frequency of 1 MHz.
Highlights
Size minimization of modern power systems, including those for communications, TV, and electric vehicle (EV) systems, has become an increasingly important objective
This paper proposes a silicon field-effect transistor (Si-FET)-based high waveforms switching frequency resonant converter, withthe a 2 displays the Power SIM (PSIM) simulation of the voltage across input capacitors, discussion of its mode analysis, voltage-balancing principles, current balancing and TL
To achieve a highly efficient converter, the optimal design based on loss analysis is required to choose a switching frequency and a value of the resonant tank that minimizes power losses
Summary
Size minimization of modern power systems, including those for communications, TV, and electric vehicle (EV) systems, has become an increasingly important objective. Size reduction of converters is oftentimes accompanied by high-frequency minimization of magnetics, i.e., inductors and transformers. Some studies have proposed certain kinds of high-frequency DC-DC topologies with softswitching [1,2,3,4,5,6,7]. Employing soft-switching methods on the main switches can reduce the switching loss and achieve higher efficiency, higher power density, and lower system costs. These cannot achieve zero-voltage switching (ZVS) in all load conditions, aside from the fact that an additional circuit potentially degrades the power density
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