• Journal of Satellite, Information and Communications
• /
• v.9 no.1
• /
• pp.90-96
• /
• 2014

This paper is about increasing transfer efficiency of wireless power transmission. The new method is proposed to detect the alignment of transmitter and receiver of wireless charger and so smart phone can display the position of wireless charging receiver on its LCD panel for the maximum charging efficiency. The previous method is only to show the transfer efficiency, but this method is to show not only the efficiency but also coordinates of receiver. The apparatus of the wireless charger is based on WPC(Wireless Power Consortium) standard and has planar air coil combined with magnet shield in Tx and Rx device so that the leakage flux is minimized on condition of under hundreds of kHz operating frequency. In this paper, it's showed that relation of magnet field and distance of each coils can be linearized and position information of Tx and Rx device is calculated thru trigonometry. Through the experiment, the obstacles of linearity are discovered and also showed that it can be optimized. and so the presented method is suitable for alignment detection method of Tx and Rx device in WPC wireless charger.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.18 no.12
• /
• pp.3315-3325
• /
• 1994

To study the variation of charging efficiency in the engine intake, the method to change the natural frequency of intake system using the intake control valve was studied and it has been used in actual engine to increase the intake air. In this paper, the method of characteristics was used to analyze the non-steady state and compared with the experimental data of the 6-cylinder diesel engine showing the effectiveness of the method theoretically.

• Journal of Electrochemical Science and Technology
• /
• v.9 no.3
• /
• pp.184-194
• /
• 2018

In this paper, we propose a rapid-charging system for the lithium-ion battery (LIB) packs used in electric forklifts. The battery offers three benefits: reduced charge time, prolonged battery life, and increased charging efficiency. A rapid-charging algorithm and DC/DC converter topology are proposed to achieve these benefits. This algorithm is developed using an electrochemical model, which controls the maximum charging current limit depending on the cell voltage and temperature. The experimental use of a selected 18650 LIB cell verified the prolongation of battery life on use of the algorithm. The proposed converter offers the same topological merits as a conventional resonant converter but solves the light-load regulation problem of conventional resonant converters by adopting pulse-width modulation. A 6.6-kW converter and charging algorithm were used with a forklift battery pack to verify this method's operational principles and advantages.

• International conference on construction engineering and project management
• /
• 2022.06a
• /
• pp.937-944
• /
• 2022

Electric vehicles (EVs) have been growing to reduce energy consumption and greenhouse gas (GHG) emissions in the transportation sector. The increasing number of EVs requires adequate recharging infrastructure, and at the same time, adopts low- or zero-emission electricity production because the GHG emissions are highly dependent on primary sources of electricity production. Although previous research has studied solar photovoltaic (PV) -integrated EV charging stations, it is challenging to optimize spatial areas between where the charging stations are required and where the renewable energy sources (i.e., solar photovoltaic (PV)) are accessible. Therefore, the primary objective of this research is to support decisions of siting EV charging stations using a spatial data clustering method integrated with Geographic Information System (GIS). This research explores spatial relationships of PV power outputs (i.e., supply) and traffic flow (i.e., demand) and tests a community in the state of Indiana, USA for optimal sitting of EV charging stations. Under the assumption that EV charging stations should be placed where the potential electricity production and traffic flow are high to match supply and demand, this research identified three areas for installing EV charging stations powered by rooftop PV in the study area. The proposed strategies will drive the transition of existing energy infrastructure into decentralized power systems. This research will ultimately contribute to enhancing economic efficiency and environmental sustainability by enabling significant reductions in electricity distribution loss and GHG emissions driven by transportation energy.

• Journal of Advanced Navigation Technology
• /
• v.19 no.3
• /
• pp.237-243
• /
• 2015

This paper presented the design of wireless power transfer (WPT) system using electromagnetic induction techniques and analysed WPT efficiency. Also, we presented the optimum coil condition by measuring the efficiency variation according to some receiving coil parameter changes. Voltage change is measured by receiving coil position for the designed transmitting and receiving circuit. Voltage change according to inductance variation at the same position and charging time are compared at the same environment by using a developed application program to realize an optimum WPT system. Developed wireless power transfer system using electromagnetic induction techniques uses 125 kHz. It takes 16 minutes by using wired charger, and 23 minutes by using wireless charger for charging from 50% to 60% charging status.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.29 no.12
• /
• pp.907-914
• /
• 2018

Wireless charging has been actively researched and popularized owing to the potential convenience of being able to charge electronic devices without wires for users. However, the receiver on the wireless charging pad is not charged when the center of the receiver is misaligned; thus, the center of the receiver must be adjusted well. This misalignment may greatly reduce the convenience of wireless charging. To overcome this limitation of wireless charging, a coil is designed to improve the positional freedom of the receiver. The positional freedom of the Rx coil is improved when the outer diameter of Tx coil is larger than when Rx and Tx coils are almost the same size. When the Tx coil has a larger outer diameter than that of the Rx coil, the efficiency at the center is somewhat lowered, but the efficiency is improved compared to when the center is out of order. In this paper, a double coil structure having an outer and an inner coil is proposed. The double coil structure further improves the efficiency, compared with one coil with the same outer size. The simulation and measurement results demonstrated that the tendency was consistent, and it was verified that the degree of freedom of the Rx coil is improved by adding the inner coil, while the size of the outer coil was the same. The measurement shows that the transmission efficiency of the conventional Tx coil is 37 %, the larger outer diameter coil is 45 %, and double coil is 47 % when the distance of the Tx/Rx coil is 3 mm, the misalignment is 15 mm and current flowing in the Rx coil is 1 A at an operating frequency of 105 to 210 kHz.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.19 no.5
• /
• pp.8-13
• /
• 2020

In this paper, the electric vehicle (EV) and internal combustion engine vehicle (ICEV) are compared for different driving cases. The EV exhibits a lower powertrain efficiency when driven on the aggressive driving cycle than when driven on the moderate cycle. In particular, EV powertrain efficiency is low when the battery state of charge (SOC) is low, but ICEV efficiency increases when the driving cycle changes from the moderate cycle to the aggressive cycle. Based on these results, attempts can be made to increase EV powertrain efficiency. EV charging before the battery power drops to a low charging state can reduce energy consumption by 2.7% for an urban area. Furthermore, ECO driving has a more significant effect on EVs than on ICEVs.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.1
• /
• pp.124-130
• /
• 2011

In this paper, We design and implementation of Self-Charging Module for charging to battery which obtaining the environment inergy such as solar energy. The power chared battery through the charging module send to sensor node. And implementation of System Activation Module(SAM) based on ID system and Dynamic Power Management Module(DPM) with SPO(Self Power Off). This system consume power only communication between the sensor nodes. We verification this system by implementing the high efficiency poweer management system.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.66 no.12
• /
• pp.1866-1872
• /
• 2017

This paper presents the design of in-wheel type Switched Reluctance Motor (SRM) which can be used as both traction motor and power pickup device in a wireless charging system of electric vehicles. The SRM acts as a traction drive in driving mode and a power receiver in charging mode to avoid any additional weights. Double stator axial field SRM is used due to its structure that can be mounted inside the wheel. The charging circuit is integrated with the asymmetric converter and phase windings of SRM, reducing the cost and size of the system. Magnetic resonance is implemented to increase the efficiency. Simulations done in Maxwell and Simplorer verify the effectiveness of the proposed system.

• Proceedings of the KIPE Conference
• /
• 2012.07a
• /
• pp.279-280
• /
• 2012

In this paper, as a part of studying the fast battery charger, designed the charging system by applying dual converter. This dual converter was applied to the charging system for reducing time by dividing high current which prevents the damage of parts from heating of components. In this paper continued the task by switching the topology of the dual converter for fast charging battery into SISO, PISO, and PIPO. The study to derive the optimized system topology by analyzing the efficiency of charging system.