• Proceedings of the KSR Conference
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• 2009.05b
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• pp.623-628
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• 2009

There is an increasing demand for efficient high power/weight auxiliary power supplies for use on high speed traction application. Many new conversion techniques have been proposed to reduce the voltage and current stress of switching components, and the switching losses in the traditional pulse width modulation(PWM) converter. Especially, the phase shift full bridge zero voltage switching PWM techniques are thought most desirable for many applications because this topology permits all switching devices to operate under zero voltage switching(ZVS) by using circuit parasitic components such as leakage inductance of high frequency transformer and power device junction capacitance. The proposed topology is found to have higher efficiency than conventional soft-switching converter. Also it is easily applicable to phase shift full bridge converter by applying an energy recovery snubber consisted of fast recovery diodes and capacitors.

• Journal of Power Electronics
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• v.11 no.4
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• pp.408-417
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• 2011

The plug-in hybrid electric vehicles (PHEVs) are specialized hybrid electric vehicles that have the potential to obtain enough energy for average daily commuting from batteries. The PHEV battery would be recharged from the power grid at home or at work and would thus allow for a reduction in the overall fuel consumption. This paper proposes an integrated power electronics interface for PHEVs, which consists of a novel Eight-Switch Inverter (ESI) and an interleaved DC/DC converter, in order to reduce the cost, the mass and the size of the power electronics unit (PEU) with high performance at any operating mode. In the proposed configuration, a novel Eight-Switch Inverter (ESI) is able to function as a bidirectional single-phase AC/DC battery charger/ vehicle to grid (V2G) and to transfer electrical energy between the DC-link (connected to the battery) and the electric traction system as DC/AC inverter. In addition, a bidirectional-interleaved DC/DC converter with dual-loop controller is proposed for interfacing the ESI to a low-voltage battery pack in order to minimize the ripple of the battery current and to improve the efficiency of the DC system with lower inductor size. To validate the performance of the proposed configuration, the indirect field-oriented control (IFOC) based on particle swarm optimization (PSO) is proposed to optimize the efficiency of the AC drive system in PHEVs. The maximum efficiency of the motor is obtained by the evaluation of optimal rotor flux at any operating point, where the PSO is applied to evaluate the optimal flux. Moreover, an improved AC/DC controller based Proportional-Resonant Control (PRC) is proposed in order to reduce the THD of the input current in charger/V2G modes. The proposed configuration is analyzed and its performance is validated using simulated results obtained in MATLAB/ SIMULINK. Furthermore, it is experimentally validated with results obtained from the prototypes that have been developed and built in the laboratory based on TMS320F2808 DSP.

• Journal of IKEEE
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• v.24 no.4
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• pp.1129-1135
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• 2020

The effects of battery aging limit the rechargeable capacity, State of Health(SoH). It is very important to estimate the SoH in the battery monitoring system(BMS) and many algorithms of measuring the internal resistance of the battery were proposed. A method is used by applying a current source of a specific frequency to the battery and measuring the voltage response. When charging harmonic noise is generated in the voltage response, it results in poor resistance measurement accuracy. In this paper, a robust battery internal resistance measurement algorithm is proposed to eliminate the effect of charging noise by integrating the current source and voltage response signals for a certain period. It showed excellent accuracy and stable measurement results. Applying to the BMS for uninterruptible power supply, the usefulness of the proposed method is verified.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.2
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• pp.165-173
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• 2022

The electrification trend of mobility increases every year due to the development of power semiconductor and battery technology. Accordingly, the development and distribution of fast chargers for electric vehicles (EVs) are in demand. In this study, we propose a design and implementation method of an LLC converter for fast chargers. Two 15 kW LLC converters are configured in parallel to have 30 kW rated output power, and the control algorithm and driving sequence are designed accordingly and verified. In addition, the improved power conversion efficiency is confirmed through zero-voltage switching (ZVS) of the LLC converter and reduction of turn-off loss through snubber capacitors. The implemented 30 kW LLC converters show a wide output voltage range of 200-950 V. Experiments applying various load conditions verify the converter performance.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.6
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• pp.587-593
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• 2011

A new high power density and low cost Photovoltaic Power Conditioning System (PV PCS) with energy storage system is proposed. Its high power density and cost effectiveness can be achieved through the unification of the maximum power point tracker and battery charger/discharger. Despite of the reduced power stage, the proposed system can achieve the same performances of maximum power point tracking and battery charging/discharging as the conventional system. Moreover, the high voltage stress across the link-capacitor can be relieved through the series-connected link-capacitor with the battery. Therefore, a large number of series/parallel-connected link-capacitors can be reduced by 4-times. Especially, when the utility power failure happens, both photovoltaic and battery energies can be supplied to the load with only one power stage. Therefore, it features a simpler structure, less mass, lower cost, and fewer devices. Finally, to confirm the operation, validity, and features of the proposed system, theoretical analysis and experimental results from a single phase AC 220Vrms/1.5kW prototype are presented.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.207-210
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• 2005

This paper describes a design of several ship's emergency lighting system(SELS) that power factor is improved and power is controlled extensively, and techniques to control and monitor this system in remote distance by PC serial communication. The remote monitoring control system is composed of emergency power supply system (EPSS), half bridge(HB)inverter, fluorescent lamp(FL), microprocessor, multi communication interface. EPSS checks the voltage of the emergency backup battery in real time. In case that the voltage of 13[V] or less has been detected for 5[msec] or longer for 3 times in a row, charger circuit is connected for battery charging. Experimental works using proposed system confirm that speedy and stable power to be supplied when main power source cut-off, compared with conventional analog type, and input power up to 35.0[%] by adjusting of pulse frequency of the HB inverter.

• Journal of IKEEE
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• v.22 no.2
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• pp.369-374
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• 2018

In this paper, the energy cost saving in multi-channel electric vehicle charging system. Joint use of the electric car charger battery state of charging proposed a method based charging. A linear programming with two type is used for optimal control, and the time-of-use price is included to calculate the energy costs. Simulation results show that the reductions of energy cost and peak power can be obtained using proposed method.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.166-167
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• 2012

본 논문은 전기자동차 (Electric Vehicles, EVs)용 리튬 이온 (Li-Ion) 배터리의 충전 및 충전 속도 향상을 위하여 6.6kW급 고전력 탑재형 충전기 (On-Board Charger, OBC)를 설계한다. 높은 부하 가변범위와 차량 실장 특성을 고려하여 가용 가능한 토폴로지들 중 최적의 토폴로지로 위상천이 풀-브릿지 컨버터 (Phase-Shift Full-Bridge, PSFB)를 제안하고 타당성을 밝힌다. 또한 토폴로지를 구동하는 스위칭 주파수와 주요 수동소자의 변화에 따른 부피와 효율 등의 Trade-Off 관계를 이론적으로 전개하여 최적화한다.

• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.3
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• pp.181-190
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• 2019

Active power decoupling circuits have emerged to eliminate the inherent second-order ripple power in a single-phase power conversion system. This study proposes a design method to determine the optimal capacitance for active power decoupling circuits to achieve high power density. Minimum capacitance is derived by analyzing ripple power in a passive power decoupling circuit, a buck-type circuit, and a capacitor-split-type circuit. Double-frequency ripple power decoupling capabilities are also analyzed in three decoupling circuits under a 3.3 kW load condition for a battery charger application. To verify the proposed design method, the performance of the three decoupling circuits with the derived minimum capacitance is compared and analyzed through the results of MATLAB -Simulink and hardware-in-the-loop simulations.

• Proceedings of the KIPE Conference
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• 2013.11a
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• pp.93-94
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• 2013

최근 하이브리드 및 전기자동차에 대한 관심이 높이지는 가운데 전기자동차용 배터리 충전기술 또한 대두 되고 있다. 본 논문은 충전 기능 만을 고려한 단방향 충전시스템에서 방전 기능을 추가한 양방향 충전시스템에 대하여 서술한다. 양방향 시스템은 차량의 배터리를 저장매체로 활용하여 계통과 배터리간의 전력을 양방향으로 전달할 수 있기 때문에 주차된 차량등의 배터리의 잉여전력을 계통으로 전송 할 수 있다. 용량은 가정용으로써 3.3kW 탑재형 단상 양방향 충/방전기에 대한 시뮬레이션을 통해 결과를 도출했다.