• 전력전자학회논문지
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• 제17권1호
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• pp.77-84
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• 2012

This paper describes the process of optimal resonant frequency design with full-bridge series-loaded resonant dc-dc converter in a high efficiency 3.3 kW on-board battery charger application for Electric Vehicles and Plug-in Hybrid Electric Vehicles. The optimal range of resonant frequency and switching frequency used for ZVS are determined by considering trade-off between loss of switching devices and resonant network with size of passive/magnetic devices. In addition, it is defined charging region of battery, the load of on-board charger, as the area of load by deliberating the characteristic of resonant. It is verified the designed frequency band by reflecting the defined area on resonant frequency.

• Journal of Power Electronics
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• 제13권6호
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• pp.964-974
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• 2013

A modified direct torque control (DTC) method based on torque angle is proposed for interior permanent-magnet synchronous motor (IPMSM) drivers used in electric vehicles (EVs). Given the close relationship between torque and torque angle, proper voltage vectors are selected by the proposed DTC method to change the torque angle rapidly and regulate the torque quickly. The amplitude and angle of the voltage vectors are determined by the torque loop and stator flux-linkage loop, respectively, with the help of the position of the stator flux linkage. Furthermore, to satisfy the torque performance request of EVs, the nonlinear dead-time of the invertor caused by parasitic capacitances is considered and compensated to improve steady torque performance. The stable operation region of the IPMSM DTC driver for voltage and current limits is investigated for reliability. The experimental results prove that the proposed DTC has good torque performance with a brief control structure.

• 센서학회지
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• 제32권6호
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• pp.462-469
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• 2023

Electric vehicles (EVs) have recently been in the spotlight and have been rapidly developed to reduce the carbon emission with respect to the transport sector. Most EVs currently employ lithium-ion batteries (LIBs) as power sources because they have a higher energy density and a lower self-discharge than other batteries. However, the LIBs cannot respond to high power demands when the state of health (SOH) falls below 80%. Therefore, the SOH of the LIBs must be accurately measured or estimated. To date, many methods have been studied and proposed for measuring or estimating the SOH. In this paper, representative methods among them are reclassified and introduced.

• Journal of Electrical Engineering and Technology
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• 제13권6호
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• pp.2220-2226
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• 2018

Electric vehicles (EVs) are significant resources for demand response (DR). Thus, it is essential for EV aggregators to quantitatively evaluate their capability for DR. In this paper, a concept of dynamic equivalent battery (DEB) is proposed as a metric for evaluating the DR performance using EVs. The DEB is the available virtual battery for DR. The capacity of DEB is determined from stochastic calculation while satisfying the charging requirements of each EV, and it varies also with time. Further, a new indicator based on the DEB and time-varying electricity prices, named as value of DEB (VoDEB), is introduced to quantify the value of DEB coupled with the electricity prices. The effectiveness of the DEB and the VoDEB as metrics for the DR performance of EVs is verified with the simulations, where the difference of charging cost reduction between direct charging and optimized bidding methods is used to express the DR performance. The simulation results show that the proposed metrics accord well with the DR performance of an EV fleet. Thus, an EV aggregator may utilize the proposed concepts of DEB and VoDEB for designing an incentive scheme to EV users, who participate in a DR program.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권10호
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• pp.4988-5012
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• 2019

As a subset of the Internet of Things, the Internet of Energy (IoE) is expected to tackle the problems faced by the current smart grid framework. Notably, the conventional day-ahead power scheduling of the smart grid should be redesigned in the IoE architecture to take into consideration the intermittence of scattered renewable generations, large amounts of power consumption data, and the uncertainty of the arrival time of electric vehicles (EVs). Accordingly, a day-ahead power scheduling system for the future IoE is proposed in this research to maximize the usage of distributed renewables and reduce carbon emission caused by the traditional power generation. Meanwhile, flexible charging mechanism of EVs is employed to provide preferred charging options for moving EVs and flatten the load profile simultaneously. The simulation results revealed that the proposed power scheduling mechanism not only achieves emission reduction and balances power load and supply effectively, but also fits each individual EV user's preference.

• 한국자동차공학회논문집
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• 제20권1호
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• pp.119-123
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• 2012

In traditional vehicles, a great amount of energy is dissipated by braking. In electric vehicles (EVs), however, electric motors can be controlled to operate as generators to convert kinetic and potential energy of vehicles into electrical energy and store it in batteries. In this paper, the relationship between regenerative braking factor and battery final SOC is derived and the final SOC from the relationship is compared to that from simulation. Two types of braking algorithms are introduced and applied to an EV, and the final SOC derived from simulation is compared to that derived from the relationship.

• 전력전자학회논문지
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• 제15권5호
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• pp.369-375
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• 2010

본 논문은 전기자동차 (Electric Vehicles, EVs) 및 플러그인 하이브리드 자동차 (Plug-In Hybrid Electric Vehicles, PHEVs)용 리튬 이온 (Li-Ion) 배터리 충전을 위한 3.3 kW급 차량 탑재형 (On-Board) 충전기 하드웨어의 설계 및 제작에 대하여 기술한다. 차량 실장 특성을 고려하여 부하직렬공진형 dc-dc 컨버터를 적용하고, 80-130kHz의 고주파 스위칭 및 ZVS (Zero-Voltage Switching) 기법을 통해 수동소자의 크기를 최적화하여 5.84L, 5.8kg의 저부피, 경량을 달성한다. 전자부하를 대상으로 정전류 (Constant Current, CC) 및 정전압 (Constant Voltage, CV) 제어를 수행하여 92.5%의 고효율 획득 및 성능을 검증한다.

• 유통과학연구
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• 제14권5호
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• pp.17-26
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• 2016

Purpose - The E-convergence economy is requested with the economic change of the diverse energy supplies, according to the exploits of Shale gas. By analyzing the electric energy supply and demand in accordance with the various cases, it has proved indirectly to create a convergence economy. Research design, data, and methodology - The research design would make realize its potential change with which government or companies have focused on the energy objection between Shale gas and Electric vehicles. Results - The paper suggests that Shale gas has expanded with the emphasis on the Electrical convergence economy or EVs. Due to these results, they also show why it should not be delayed in the development of shale gas and electric vehicles at the same time. Conclusions - All this is from the reason of opening the E-convergence economy over time. It is required that Korea should prepare E-convergence economy. Public regional energy should be present through the consistent selection of development for energy linking E-economy and E-trans distribution.

• Journal of international Conference on Electrical Machines and Systems
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• 제1권2호
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• pp.105-110
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• 2012

This paper designs the high-efficiency and the low-cost drive system of the smallsize electric vehicles (EVs). The power circuit for driving the dc motor is designed by considering both the cost and efficiency. In order to reduce the conduction loss of MOTFET and diode for controlling an armature voltage, some MOSFETs and diodes at the armature are in parallel connection. An operating sequence for both the field current and the armature voltage according to the accelerator pedal angle is suggested for changing smoothly the rotating direction of dc motor. Through the simulation studies, the performances of the proposed methods are verified.

• 전기학회논문지
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• 제61권11호
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• pp.1634-1640
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• 2012

This paper develops the high-efficiency drive system of the small-size electric vehicles (EVs) driven by the brushed dc motors. A power circuit for driving the dc motor is designed with the H-bridge circuit and buck converter by considering both the efficiency and cost. In order to change smoothly the rotating direction of dc motor driven by the proposed power circuit, an operating sequence for both the field current and the armature voltage according to an accelerator pedal angle is suggested. Through the simulation studies and experimental results with the low-cost 8-bit AVR, the performances of the proposed methods are verified.