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Yun H.-J.,Power Conversion and Control Research Center | Kim J.-H.,Power Conversion and Control Research Center | Ryu M.-H.,Power Conversion and Control Research Center | Kim H.-J.,Pusan National University
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2013

In this paper, a boost PFC rectifier with a novel passive lossless snubber circuit is proposed to minimize switching loss in high power applications. A new turn-on mechanism of the lossless snubber using coupled inductor is applied to reduce the reverse recovery loss of the output diode rectifier. The turn-off operation of the lossless snubber is composed of a single capacitor and two diodes to reduce the voltage stress and the power loss at the turn-off of the switch. Due to the lossless clamping operation, the proposed PFC operates under soft switching conditions with high power conversion efficiency. The design and performance of the boost PFC rectifier using the proposed lossless snubber are verified by experimental results using a 3.3kW prototype rectifier. © 2013 Springer-Verlag Berlin Heidelberg. Source

Jeong D.-K.,Pusan National University | Jeong D.-K.,Power Conversion and Control Research Center | Ryu M.-H.,Power Conversion and Control Research Center | Kim H.-G.,Kyungpook National University | Kim H.-J.,Pusan National University
Journal of Power Electronics | Year: 2014

This study proposes an optimized design of a dual active bridge converter for a low-voltage charger in a military uninterrupted power supply (UPS) system. The dual active bridge converter is among various bi-directional DC/DC converters that possess a high-efficiency isolated bi-directional converter. In the general design, the zero-voltage switching(ZVS) region is reduced when the battery voltage is high. By contrast, efficiency is low because of high conduction losses when the battery voltage is low. Variable switching frequency is applied to increase the ZVS region and the power conversion efficiency, depending on battery voltage changes. At the same duty, the same power is obtained regardless of the battery voltage using the variable switching frequency. The proposed method is applied to a 5 kW prototype dual active bridge converter, and the experimental results are analyzed and verified. © 2014 KIPE. Source

Lee K.-J.,Pusan National University | Cha H.,Kyungpook National University | Lee J.-P.,Power Conversion and Control Research Center | Yoo D.-W.,Power Conversion and Control Research Center | Kim H.-J.,Pusan National University
Journal of Power Electronics | Year: 2013

This paper introduces a simple core loss calculation method for output filter inductor in pulse width modulation (PWM) DC-AC inverter. Amorphous C-core (AMCC-320) is used to analyze the core loss. In order to measure core loss of the output filter inductor and validate the proposed method, a single-phase half-bridge inverter and a calorimeter are used. By changing switching frequency and modulation index (MI) of the inverter, core loss of the AMCC-320 is measured with the lab-made calorimeter and the results are compared with calculated core loss. The proposed method can be easily extended to other core loss calculation of various converters. Source

Lee J.-P.,Power Conversion and Control Research Center | Cha H.,Kyungpook National University | Shin D.,Pusan National University | Lee K.-J.,Pusan National University | And 2 more authors.
Journal of Power Electronics | Year: 2013

Multiphase dc-dc converters are widely used in modem power electronics applications due to their advantages over single-phase converters. Such advantages include reduced current stress in both the switching devices and passive elements, reduced output current ripple, and so on. Although the output current ripple of a converter can be significantly reduced by virtue of the interleaving effect, the inductor current ripple cannot be reduced even with the interleaving PWM method. One way to solve this problem is to use a coupled inductor. However, care must be taken in designing the coupled inductor to maximize its performances. In this paper, a detailed analysis of a coupled inductor is conducted and the effect of a coupled inductor on current ripple reduction is investigated extensively. From this analysis, a UU core based coupled inductor structure is proposed to maximize the performance of the coupled inductor. Source

Jeong D.-K.,Pusan National University | Jeong D.-K.,Power Conversion and Control Research Center | Baek J.-W.,Power Conversion and Control Research Center | Cho J.-T.,Korea Electric Power Research Institute | And 2 more authors.
9th International Conference on Power Electronics - ECCE Asia: "Green World with Power Electronics", ICPE 2015-ECCE Asia | Year: 2015

In order to increase the reliability and response speed of a DC microgrid system, the power management algorithm for autonomous operation is proposed using a DC-bus signaling (DBS) method, instead of the centralized power management system which needs communications among power interfaces. The DC-bus voltage is considered as an information signal of the status of the DC-bus. In addition, DC-bus voltage bands are proposed to classify the scenarios of DC-bus conditions. The DC microgrid components individually operate to achieve the functionality of the system control in the DC-bus voltage band. This paper suggests a control strategy for the power management among independent components in the islanding mode. Its test-bed contains the power management algorithm which consists of a grid-connected AC/DC rectifier, a bidirectional DC/DC converter, a renewable energy simulator, DC loads, and a DC-bus protector. The proposed power management algorithm in the islanding mode is analyzed via simulation result, which is verified from the proposed DC microgrid test-bed. © 2015 Korean Institute of Power Electronics. Source

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