scispace - formally typeset
Search or ask a question
Author

Seho Kim

Bio: Seho Kim is an academic researcher from University of Auckland. The author has contributed to research in topics: Maximum power transfer theorem & Electromagnetic coil. The author has an hindex of 8, co-authored 17 publications receiving 277 citations.

Papers
More filters
Journal ArticleDOI
TL;DR: In this article, a Tripolar Pad (TPP) primary is evaluated for 3.3 kW power transfer to both a circular pad and a bipolar pad as secondary pads, and a mathematical model is presented to describe the power transfer from the TPP primary to the secondary pads then a control scheme is proposed which exploits the mutual decoupling between the TPP coils to find optimal primary currents.
Abstract: A recently proposed magnetic structure called Tripolar Pad (TPP) is investigated as a primary pad in an inductive power transfer battery charging system for electric vehicles. In this paper, a TPP primary is evaluated for 3.3 kW power transfer to both a circular pad and a bipolar pad as secondary pads. A mathematical model is presented to describe the power transfer from the TPP primary to the secondary pads then a control scheme is proposed which exploits the mutual decoupling between the TPP coils to find optimal primary currents. The optimization of the primary currents in the TPP improved the effective coupling factor over traditional topologies, particularly when the secondary was misaligned, and maintained leakage magnetic flux below International Commission on Non-Ionizing Radiation Protection guidelines. The result for the proposed TPP is validated with practical measurements.

210 citations

Journal ArticleDOI
TL;DR: In this paper, the authors evaluate the effective coupling factor and leakage magnetic field of a 20-kW inductive power transfer (IPT) system that uses a combination of tripolar pad and circular pad (CP) topologies over a range of lateral displacements.
Abstract: Recently, a magnetic pad called the tripolar pad (TPP) has been introduced for inductive power transfer (IPT) systems. This paper evaluates the effective coupling factor and leakage magnetic field of a 20-kW IPT system that uses a combination of TPP and circular pad (CP) topologies over a range of lateral displacements. The results show that the effective coupling factor and the leakage magnetic field of the TPP–TPP system are substantially better when the secondary is displaced away from ideal alignment. Leakage magnetic field is reduced up to 43% compared to the CP–CP system at the worst-case misalignment, which is due to the ability of the TPP–TPP system to generate and capture different types of magnetic field shapes. Simulation methods for both the TPP and CP are validated in the laboratory using a 2-kW system operating at 85 kHz.

63 citations

Journal ArticleDOI
Abiezer Tejeda1, Seho Kim1, Fei Yang Lin1, Grant A. Covic1, John T. Boys1 
TL;DR: In this paper, the authors proposed a hybrid solenoid for wireless charging applications, which is able to transfer high power over large air gaps and is tolerant to lateral displacements suitable for electric vehicle charging applications.
Abstract: This paper introduces a primary pad for wireless charging applications, which is able to transfer high power over large air gaps and is tolerant to lateral displacements suitable for electric vehicle charging applications. The developed pad is an improved solenoid designed specifically to address issues such as flux leakage and loss while retaining good coupling. It is a hybrid structure that consists of a combination of rectangular- or square-shaped coils and a central solenoid, all connected in series. When energized, it produces a single-sided, polarized flux similar to the flux pattern of the solenoid and double D (DDP) pads. The power transfer capability of this pad is investigated through finite-element analysis simulations. The results are compared first to a similar sized solenoid from which it was derived, and also a DDP primary pad and are verified through measurements on prototype systems in the laboratory. The aim of this paper is to provide an improved hybrid solenoid pad showing higher coupling factors and lower stray field emissions with a performance (coupling and stray field emissions) similar to that of DDPs.

36 citations

Journal ArticleDOI
04 Jan 2017
TL;DR: In this paper, the effective coupling factor between the BPP primary and secondary depends on the coupling factors that exist between each primary coil and the secondary coil, the reflected impedances, and the relative magnitude and phase of currents between the primary coils.
Abstract: Inductive power transfer is a method of delivering power from a source to a load by resonating inductive coils in proximity with each other. Two main pad topologies exist: one that can generate nonpolarized and one that can generate polarized fields. Multicoil pads such as bipolar pads (BPPs) have been proposed as a pad topology that is interoperable with both polarized and nonpolarized pads. BPPs comprise two ideally overlapped mutually decoupled coils, which can be driven in any relative magnitude or phase. A polarized pad structure, such as a double d pad, is not equivalent to a BPP, and the polarized pad is a subset of the multicoil pad. It also shows that the effective coupling factor ( $k_{\mathrm {eff}}$ ) between the BPP primary and the secondary depends on the coupling factors that exist between each primary coil and the secondary coil, the reflected impedances, and the relative magnitude and phase of currents between the primary coils. An equation that describes $k_{\mathrm {eff}}$ is proposed and considers all these factors to show how each coil in a BPP can be energized to control VA transfer.

36 citations

Proceedings ArticleDOI
01 Oct 2014
TL;DR: The Tripolar Pad is proposed, a novel three coil magnetic pad utilising mutually decoupled coils that maintains tolerance to rotational displacements similar to nonpolarised pads, but uses polarised fields to improve power transfer.
Abstract: Inductive Power Transfer (TPT) systems have been proposed in recent years as a safe, convenient and robust method of battery charging in EVs and robots. In an IPT system, the magnetic design of the primary and secondary pads is an important factor that determines the power transfer capability. This paper proposes the Tripolar Pad (TPP), a novel three coil magnetic pad utilising mutually decoupled coils. The TPP maintains tolerance to rotational displacements similar to nonpolarised pads, but uses polarised fields to improve power transfer. Simulation results are first shown in the paper and then validated by a scaled prototype.

32 citations


Cited by
More filters
Journal ArticleDOI
01 Mar 2018
TL;DR: In this paper, a comprehensive review of charging pad, power electronics configurations, compensation networks, controls, and standards is presented, along with a detailed analysis of the charging range of EVs.
Abstract: More than a century-old gasoline internal combustion engine is a major contributor to greenhouse gases. Electric vehicles (EVs) have the potential to achieve eco-friendly transportation. However, the major limitation in achieving this vision is the battery technology. It suffers from drawbacks such as high cost, rare material, low energy density, and large weight. The problems related to battery technology can be addressed by dynamically charging the EV while on the move. In-motion charging can reduce the battery storage requirement, which could significantly extend the driving range of an EV. This paper reviews recent advances in stationary and dynamic wireless charging of EVs. A comprehensive review of charging pad, power electronics configurations, compensation networks, controls, and standards is presented.

553 citations

Journal ArticleDOI
TL;DR: In this article, a Tripolar Pad (TPP) primary is evaluated for 3.3 kW power transfer to both a circular pad and a bipolar pad as secondary pads, and a mathematical model is presented to describe the power transfer from the TPP primary to the secondary pads then a control scheme is proposed which exploits the mutual decoupling between the TPP coils to find optimal primary currents.
Abstract: A recently proposed magnetic structure called Tripolar Pad (TPP) is investigated as a primary pad in an inductive power transfer battery charging system for electric vehicles. In this paper, a TPP primary is evaluated for 3.3 kW power transfer to both a circular pad and a bipolar pad as secondary pads. A mathematical model is presented to describe the power transfer from the TPP primary to the secondary pads then a control scheme is proposed which exploits the mutual decoupling between the TPP coils to find optimal primary currents. The optimization of the primary currents in the TPP improved the effective coupling factor over traditional topologies, particularly when the secondary was misaligned, and maintained leakage magnetic flux below International Commission on Non-Ionizing Radiation Protection guidelines. The result for the proposed TPP is validated with practical measurements.

210 citations

Journal ArticleDOI
TL;DR: A hybrid wireless power transfer (WPT) system that charges EVs at constant rate despite large misalignments between charging pads is presented and results clearly indicate that the proposed hybrid WPT system is efficient and offers a constant charging profile over a wide range of spatial (three-dimensional) pad mis alignments.
Abstract: Electric vehicles (EVs) are becoming increasingly popular as a means of future transport for sustainable living. However, wireless charging of EVs poses a number of challenges related to interoperability, safety, pad misalignment, etc. In particular, pad misalignments invariably cause changes in system parameters which in turn lead to increase in losses as well as reduction in power throughput, making the charging process long and inefficient. Consequently, wireless charging systems that are less sensitive to pad misalignments have become preferable. This paper, therefore, presents a hybrid wireless power transfer (WPT) system that charges EVs at constant rate despite large misalignments between charging pads. The proposed charging system uses a combination of two different resonant networks to realize a constant and efficient charging process. A mathematical model is also developed, showing as to how the two resonant networks can be combined to compensate for pad misalignments. To demonstrate the validity of the proposed concept as well as the accuracy of the mathematical model, theoretical performance is compared with both simulations and experimental results of a prototype 3.3 kW hybrid bidirectional WPT system. Results clearly indicate that the proposed hybrid WPT system is efficient and offers a constant charging profile over a wide range of spatial (three-dimensional) pad misalignments.

190 citations

Journal ArticleDOI
TL;DR: A thorough literature review on the wireless charging technology for EVs is presented, including an innovative approach towards the use of superconducting material in coil designs is investigated, and their potential impact on wireless charging is discussed.
Abstract: Electric vehicles (EVs) have recently been significantly developed in terms of both performance and drive range. There already are various models commercially available, and the number of EVs on road increases rapidly. Although most existing EVs are charged by electric cables, companies like Tesla, BMW and Nissan have started to develop wireless charged EVs that don’t require bulky cables. Rather than physical cable connection, the wireless (inductive) link effectively avoids sparking over plugging/unplugging. Furthermore, wireless charging opens new possibilities for dynamic charging – charging while driving. Once realised, EVs will no longer be limited by their electric drive range and the requirement for battery capacity will be greatly reduced. This has been prioritised and promoted worldwide, particularly in UK, Germany and Korea. This paper presents a thorough literature review on the wireless charging technology for EVs. The key technical components of wireless charging are summarised and compared, such as compensation topologies, coil design and communication. To enhance the charging power, an innovative approach towards the use of superconducting material in coil designs is investigated and their potential impact on wireless charging is discussed. In addition, health and safety concerns about wireless charging are addressed, as well as their relevant standards. Economically, the costs of a wide range of wireless charging systems has also been summarised and compared.

169 citations

Journal ArticleDOI
TL;DR: A novel series-hybrid topology in which the series inductors of the primary and pick-up inductor–capacitor–inductor (LCL) networks are integrated into polarized magnetic couplers to improve the system performance under pad misalignment is presented.
Abstract: Electric vehicles (EVs) are becoming increasingly popular as a mean of mitigating issues associated with fossil fuel consumption in transportation systems. A wireless inductive power transfer (IPT) interface between EV and the utility grid has several key advantages, such as safety, convenience, and isolation. However, physical misalignments between the pads of IPT charging systems used in EVs are unavoidable and cause variations in key system parameters, significantly increasing losses and affecting power throughput. This paper presents a novel series-hybrid topology in which the series inductors of the primary and pick-up inductor–capacitor–inductor ( LCL ) networks are integrated into polarized magnetic couplers to improve the system performance under pad misalignment. A mathematical model is developed to investigate the behavior of the proposed system under misalignment. To demonstrate the viability of the proposed method, the results of a 3.3-kW prototype series-hybrid IPT system are presented, benchmarked against a conventional IPT system. Experimental results clearly indicate that the proposed system maintains the output power within ±5% of its rated power despite the pad misalignment. The proposed system is efficient, reliable, and cost effective in comparison to conventional LCL- and CL -compensated IPT systems.

168 citations