Jong-Seob Won

A novel LLC resonant converter for wide input voltage and load range

Nowadays, some applications require high efficiency under wide load range and wide input variation. In order to get high voltage gain characteristics in a wide input and load ranges, the conventional LLC resonant converter requires a small magnetizing inductance, and a lot of losses by the higher magnetizing current can be generated in the switches and transformer. The proposed LLC resonant converter with two resonant tank circuits and auxiliary switches, even though large magnetizing inductance of the transformer is used, can get the high voltage gain characteristics in a wide input voltage and load ranges. Also, due to the reduced magnetizing current, losses and efficiency characteristics can respectively be reduced and improved. The proposed LLC resonant converter is described and verified through a 500W experimental prototype.

Operation characteristics of two-stage DC/DC converter for photovoltaic system

Solar cell is one of the most important new renewable energy sources for future energy generation. This paper presents a novel two stage DC/DC converter topology for photovoltaic (PV) power conditioning systems (PCSs). The proposed converter consists of an interleaved boost converter and a two-tank LLC resonant converter which is connected in parallel in primary and series in secondary. The main idea of the topology is that the system can achieve either unilateral or bilateral operations along with the level of output voltage from the PV module, which accordingly leads to an enhanced performance.

Study on control system design for washer fluid heating system

This paper presents the design of a control system for improving performance of a washer fluid heating system (WFHS) which is capable of removing frost, ice, snow and/or other debris from windshield. First, for the WFHS, a modeling process is described, and the extraction of characteristic parameters of the model are made by experimental studies. Design variables that affect on performance of the WFHS are also presented. Secondly, a control system is proposed for improving heating performance of the WFHS, and its performance is verified through experiments. The key feature of the proposed control system is to regulate the current of a booster converter input to the WFHS up to the target value that is set to guarantee heating performance. Target current is calculated by using initial temperature value and employing the mathematical model derived in the paper. Computer simulation and experimental results show that the proposed control system can perform heating operations in a way to satisfy per-determined target performance of the WFHS.

A novel integrated 2-in-1 transformer

In this paper, a novel integrated transformer applicable to LLPs with output capacity of 150W is proposed, which is comprised of a PFC inductor and an LLC resonant transformer by integrating them on a single magnetic core. The shape of bobbin applicable to PCB layout design is also proposed. Through a set of experiments, the applicability of the proposed design and its feasibility in terms of cost reduction, weight-lighting, and size are investigated.

An Integrated Transformer-based LED Power Supply with Wide-Output-Voltage Control

In this paper, implementation of an integrated transformer applicable to power supply units (PSUs) for a 150-W LED with a wide range of output voltage is presented. The transformer is comprised of a PFC inductor and an LLC resonant transformer, each of which is placed and integrated on an E–I–E-type magnetic core. Integrated transformers with two different air gap topologies (i.e., the side and center gap topologies) are considered in the design phase to investigate their applicability. The design consideration on the LLC resonant converter used for the wide-output-voltage control ranges is described, and the overall performance of the proposed system is verified through realization of it onto a 150-W LED PSU board.

AC-DC Converter using the PFC Inductor and LLC Resonant Transformer with an Integrated Magnetic Core

An integrated two-in-one transformer applicable to PSUs for a 120 W LED TV is proposed. This transformer comprises a PFC inductor and an LLC transformer placed and integrated on an E-I-E type magnetic core. Performance is evaluated by observing the coupling coefficients of the proposed two-in-one transformer under various air gap topologies. Among the topologies studied, an integrated transformer with centered air gap shows stable operational characteristics with a minimized mutual coupling (interference). Furthermore, applicability of the proposed integrated transformer to PSUs for a 120 W LED TV is studied from the viewpoint of integrating different magnetic components into one core, resulting to low weight, low cost, and high power density.

Implementation of a 2-in-1 transformer combined with a PFC inductor and an LLC transformer for PSUs

In this paper, Implementation of an integrated 2-in-1 transformer applicable to power supply units (PSUs) for a 120W LED TV is presented. The transformer is comprised a PFC inductor and an LLC resonant transformer, each of which is placed and integrated on an E-I-E type magnetic core. Integrated transformers with two different air gap topologies (i.e., the side gap and center gap topologies) are considered in the design phase and their performances are analyzed through various approaches. Applicability of the proposed integrated transformer to PSUs for a 120W LED TV is found from the viewpoint of integration of different magnetic components into one core, which leads to light weight, low cost, high power density, and so on.

Two Stage DC/DC Converter for Photovoltaic Generation

Solar cell is one of the most important new renewable energy for future energy generation. This paper presents a novel two stage DC/DC converter topology for PV PCSs. The proposed converter consists of an interleaved boost converter and a two-tank LLC resonant converter which is connected in parallel in primary and series in secondary. The main idea of this topology is that the system can achieve either unilateral or bilateral operations due to the input voltage level of the PV module, which leads to a better performance. The operating schemes on the proposed converter are analyzed and described. A 2.2kW prototype product is built, tested and verified.