Research

11 pages, 9962 KiB

Open AccessArticle

Analysis and Introduction of Effective Permeability with Additional Air-Gaps on Wireless Power Transfer Coils for Electric Vehicle Based on SAE J2954 Recommended Practice

by Dongwook Kim, Hongseok Kim, Anfeng Huang, Qiusen He, Hanyu Zhang, Seungyoung Ahn, Yuyu Zhu and Jun Fan

Energies 2019, 12(24), 4797; https://doi.org/10.3390/en12244797 - 16 Dec 2019

Cited by 11 | Viewed by 4268

Abstract

The wireless power transfer (WPT) method for electric vehicles (EVs) is becoming more popular, and to ensure the interoperability of WPT systems, the Society of Automotive Engineers (SAE) established the J2954 recommended practice (RP). It includes powering frequency, electrical parameters, specifications, testing procedures, [...] Read more.

The wireless power transfer (WPT) method for electric vehicles (EVs) is becoming more popular, and to ensure the interoperability of WPT systems, the Society of Automotive Engineers (SAE) established the J2954 recommended practice (RP). It includes powering frequency, electrical parameters, specifications, testing procedures, and other contents for EV WPT. Specifically, it describes the ranges of self-inductances of the transmitting coil, the receiving coil, and coupling coefficient (k), as well as the impedance matching values of the WPT system. Following the electrical parameters listed in SAE J2954 RP is crucial to ensure the EV wireless charging system is interoperable. This paper introduces a method for adjusting the effective permeability of the ferrite blocks in the standard model, to tune the self-inductance of the coils as well as the coupling coefficient. To guarantee the given values of the self-inductance of the coil and coupling coefficient matched those in the standard, we slightly modified the air-gap between the ferrite tiles in a specific region. Based on this method, it was possible to successfully tune the self-inductance of the transmitting coil and receiving coil as well as the coupling coefficient. The proposed method was verified by simulation and experimental measurements. Full article

(This article belongs to the Special Issue Wireless Power for Electric Vehicles)

► Show Figures

Graphical abstract

47 pages, 24778 KiB

Open AccessArticle

Optimization of the Alignment Method for an Electric Vehicle Magnetic Field Wireless Power Transfer System Using a Low-Frequency Ferrite Rod Antenna

by Jae Yong Seong and Sang-Sun Lee

Energies 2019, 12(24), 4689; https://doi.org/10.3390/en12244689 - 09 Dec 2019

Cited by 9 | Viewed by 3515

Abstract

The establishment of international and regional standards for electric vehicle (EV) magnetic field wireless power transfer (MF-WPT) systems started in 2010 by the Society of Automotive Engineers (SAE). In the meantime, the EV MF-WPT standardization has been focused on primary device and secondary [...] Read more.

The establishment of international and regional standards for electric vehicle (EV) magnetic field wireless power transfer (MF-WPT) systems started in 2010 by the Society of Automotive Engineers (SAE). In the meantime, the EV MF-WPT standardization has been focused on primary device and secondary device topology. Recently, the International Organization for Standardization (ISO), the International Electrotechnical Commission (IEC), and SAE have begun describing the communication and alignment techniques for EV MF-WPT. In this paper, we present a fine positioning method using a low-frequency (LF) signal, as mentioned in IEC 61980 and SAE J2954. Through modeling and simulation, we optimized a LF ferrite rod antenna (FRA) for EV MF-WPT fine positioning. We also found the optimal arrangement of LF-FRAs on primary device and secondary device Finally, we used a test bench to experiment and check the results of our proposal. Full article

(This article belongs to the Special Issue Wireless Power for Electric Vehicles)

► Show Figures

Figure 1

21 pages, 9292 KiB

Open AccessArticle

Finite Element Modeling and Analysis of High Power, Low-loss Flux-Pipe Resonant Coils for Static Bidirectional Wireless Power Transfer

by Babatunde Olukotun, Julius Partridge and Richard Bucknall

Energies 2019, 12(18), 3534; https://doi.org/10.3390/en12183534 - 15 Sep 2019

Cited by 12 | Viewed by 4125

Abstract

This paper presents the optimal modeling and finite element analysis of strong-coupled, high-power and low-loss flux-pipe resonant coils for bidirectional wireless power transfer (WPT), applicable to electric vehicles (EVs) using series-series compensation topology. The initial design involves the modeling of strong-coupled flux-pipe coils [...] Read more.

This paper presents the optimal modeling and finite element analysis of strong-coupled, high-power and low-loss flux-pipe resonant coils for bidirectional wireless power transfer (WPT), applicable to electric vehicles (EVs) using series-series compensation topology. The initial design involves the modeling of strong-coupled flux-pipe coils with a fixed number of wire-turns. The ohmic and core loss reduction for the optimized coil model was implemented by creating two separate coils that are electrically parallel but magnetically coupled in order to achieve maximum flux linkage between the secondary and primary coils. Reduction in the magnitude of eddy current losses was realized by design modification of the ferrite core geometry and optimized selection of shielding material. The ferrite core geometry was modified to create a C-shape that enabled the boosting and linkage of useful magnetic flux. In addition, an alternative copper shielding methodology was selected with the advantage of having fewer eddy current power losses per unit mass when compared with aluminum of the same physical dimension. From the simulation results obtained, the proposed flux-pipe model offers higher coil-to-coil efficiency and a significant increase in power level when compared with equivalent circular, rectangular and traditional flux-pipe models over a range of load resistance. The proposed model design is capable of transferring over 11 kW of power across an airgap of 200 mm with a coil-to-coil efficiency of over 99% at a load resistance of 60 Ω. Full article

(This article belongs to the Special Issue Wireless Power for Electric Vehicles)

► Show Figures

Figure 1

19 pages, 5664 KiB

Open AccessArticle

A Comparative Study of S-S and LCCL-S Compensation Topologies in Inductive Power Transfer Systems for Electric Vehicles

by Yafei Chen, Hailong Zhang, Sung-Jun Park and Dong-Hee Kim

Energies 2019, 12(10), 1913; https://doi.org/10.3390/en12101913 - 18 May 2019

Cited by 18 | Viewed by 3429

Abstract

In inductive power transfer (IPT) systems, series–series (S-S) and double capacitances and inductances–series (LCCL-S) compensation topologies are widely utilized. In this study, the basic characteristics of S-S and LCCL-S are analyzed and compared in the tuning state. In addition, considering the universality of [...] Read more.

In inductive power transfer (IPT) systems, series–series (S-S) and double capacitances and inductances–series (LCCL-S) compensation topologies are widely utilized. In this study, the basic characteristics of S-S and LCCL-S are analyzed and compared in the tuning state. In addition, considering the universality of detuning, and because the two topologies have the same secondary structures, the voltage and current stress on components, input impedances, voltage gains, and output powers of S-S and LCCL-S are mainly analyzed and compared in the detuning state, which is caused by variations in the secondary compensation capacitance. To compare the efficiency of the two topologies and verify the comparative analysis, comparative experiments based on a 2.4-kW IPT experimental prototype are conducted. The comparative result shows that the S-S compensation topology is more sensitive to load variations and less sensitive to secondary compensation capacitance variations than LCCL-S. Both in the tuning and detuning states, the efficiency of the S-S topology is higher in high-power electric vehicle (EV) applications, and the efficiency of LCCL-S is higher in low-power. Full article

(This article belongs to the Special Issue Wireless Power for Electric Vehicles)

► Show Figures

Figure 1

24 pages, 10468 KiB

Open AccessArticle

Magnetic Field during Wireless Charging in an Electric Vehicle According to Standard SAE J2954

by Tommaso Campi, Silvano Cruciani, Francesca Maradei and Mauro Feliziani

Energies 2019, 12(9), 1795; https://doi.org/10.3390/en12091795 - 11 May 2019

Cited by 54 | Viewed by 5877

Abstract

The Society of Automotive Engineers (SAE) Recommended Practice (RP) J2954 (November 2017) was recently published to standardize the wireless power transfer (WPT) technology to recharge the battery of an electric vehicle (EV). The SAE J2954 RP establishes criteria for interoperability, electromagnetic compatibility (EMC), [...] Read more.

The Society of Automotive Engineers (SAE) Recommended Practice (RP) J2954 (November 2017) was recently published to standardize the wireless power transfer (WPT) technology to recharge the battery of an electric vehicle (EV). The SAE J2954 RP establishes criteria for interoperability, electromagnetic compatibility (EMC), electromagnetic field (EMF) safety, etc. The aim of this study was to predict the magnetic field behavior inside and outside an EV during wireless charging using the design criteria of SAE RP J2954. Analyzing the worst case configurations of WPT coils and EV bodyshell by a sophisticated software tool based on the finite element method (FEM) that takes into account the field reflection and refraction of the metal EV bodyshell, it is possible to numerically assess the magnetic field levels in the environment. The investigation was performed considering the worst case configuration—a small city car with a Class 2 WPT system of 7.7 kVA with WPT coils with maximum admissible ground clearance and offset. The results showed that the reference level (RL) of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines in terms of magnetic flux density was exceeded under and beside the EV. To mitigate the magnetic field, the currents flowing through the WPT coils were varied using the inductor-capacitor-capacitor (LCC) compensation instead of the traditional series-series (SS) compensation. The corresponding calculated field was compliant with the 2010 ICNIRP RL and presented a limited exceedance of the 1998 ICNIRP RL. Finally, the influence of the body width on the magnetic field behavior adopting maximum offset was investigated, demonstrating that the magnetic field emission in the environment increased as the ground clearance increased and as the body width decreased. Full article

(This article belongs to the Special Issue Wireless Power for Electric Vehicles)

► Show Figures

Figure 1

10 pages, 3238 KiB

Open AccessArticle

A Compact Spatial Free-Positioning Wireless Charging System for Consumer Electronics Using a Three-Dimensional Transmitting Coil

by Ziwei Liang, Jianqiang Wang, Yiming Zhang, Jiuchun Jiang, Zhengchao Yan and Chris Mi

Energies 2019, 12(8), 1409; https://doi.org/10.3390/en12081409 - 12 Apr 2019

Cited by 11 | Viewed by 2674

Abstract

A compact spatial free-positioning wireless charging system with a novel three-dimensional (3D) transmitting (Tx) coil is proposed to charge consumer electronics in the working area. Because of the strengthened electromagnetic field generated by the proposed 3D Tx coil in the space, this system [...] Read more.

A compact spatial free-positioning wireless charging system with a novel three-dimensional (3D) transmitting (Tx) coil is proposed to charge consumer electronics in the working area. Because of the strengthened electromagnetic field generated by the proposed 3D Tx coil in the space, this system can charge consumer electronics wirelessly with great tolerance to positional and angular misalignments between the transmitter and receiver. Benefiting from the compact design of the 3D Tx coil, the system can be easily embedded in some corners of office furniture/cubic panels, which will not cause any extra working space consumption when charging devices. The inductor-capacitor-capacitor (LCC) compensation circuit on the Tx side can achieve constant current output, which is independent of load condition and can protect the transmitter. With the LCC compensation circuit, the MOSFETs of the H-bridge high-frequency inverter realized zero voltage switching (ZVS). The small-sized planar receiving (Rx) coil and series (S) compensation circuit is applied to achieve compact receiver design. The theoretical and experimental results show that the spatial free-positioning wireless charging prototype can transfer 5 W to the small-sized receiver in around 350 mm × 225 mm × 200 mm 3D charging area and achieve the highest efficiency of 77.9%. Full article

(This article belongs to the Special Issue Wireless Power for Electric Vehicles)

► Show Figures

Figure 1

13 pages, 5502 KiB

Open AccessArticle

Integrated Control Strategy for Inductive Power Transfer Systems with Primary-Side LCC Network for Load-Average Efficiency Improvement

by Sangjoon Ann, Woo-Young Lee, Gyu-Yeong Choe and Byoung Kuk Lee

Energies 2019, 12(2), 312; https://doi.org/10.3390/en12020312 - 19 Jan 2019

Cited by 7 | Viewed by 3379

Abstract

An inductive power transfer (IPT) system has lower peak efficiency and significantly lower load-average efficiency over the entire range of output power than typical power conversion systems because it transmits power wirelessly through magnetically coupled coils. In order to improve the load-average efficiency [...] Read more.

An inductive power transfer (IPT) system has lower peak efficiency and significantly lower load-average efficiency over the entire range of output power than typical power conversion systems because it transmits power wirelessly through magnetically coupled coils. In order to improve the load-average efficiency of the IPT system, this paper proposes an integrated control strategy consisting of full-bridge, phase-shift, and half-bridge control modes. The coupling coefficient and output power conditions for each control mode are theoretically analyzed, and the proposed control algorithm is established. In order to verify the analysis results, a 3.3 kW IPT system prototype is constructed, and it is experimentally verified that the load-average efficiency is improved by up to 3.75% with respect to the output power when using the proposed control scheme. In addition, the proposed control has the additional advantage that it can be directly applied to the existing IPT system without changing or adding hardware. Full article

(This article belongs to the Special Issue Wireless Power for Electric Vehicles)

► Show Figures

Figure 1

14 pages, 3627 KiB

Open AccessArticle

An LCC-P Compensated Wireless Power Transfer System with a Constant Current Output and Reduced Receiver Size

by Zhengchao Yan, Yiming Zhang, Baowei Song, Kehan Zhang, Tianze Kan and Chris Mi

Energies 2019, 12(1), 172; https://doi.org/10.3390/en12010172 - 06 Jan 2019

Cited by 36 | Viewed by 5765

Abstract

Wireless Power Transfer (WPT) for autonomous underwater vehicles (AUVs) has been a research focus in recent years. This paper studies the inductor-capacitor-capacitor and parallel (LCC-P) compensation topology to achieve a compact receiver for AUVs. Unlike the series-series (SS) compensation topology, the LCC-P topology [...] Read more.

Wireless Power Transfer (WPT) for autonomous underwater vehicles (AUVs) has been a research focus in recent years. This paper studies the inductor-capacitor-capacitor and parallel (LCC-P) compensation topology to achieve a compact receiver for AUVs. Unlike the series-series (SS) compensation topology, the LCC-P topology retains the advantages of the double-sided LCC topology and has a more compact receiver than the double-sided LCC topology with fewer elements used on the receiver side. The analytical model of such a WPT system is established to analyze the output power and transfer efficiency. The LCC-P topology has a higher efficiency compared to the SS topology due to the smaller conduction loss of the inverter. Moreover, a method of eliminating the DC filter inductor L₀ is proposed to further decrease the size and weight of the receiver. The amplitude of the withstanding voltage on the receiver compensation capacitor without L₀ is approximately decreased by 40% compared to that with L₀. Both cases of with and without L₀ have a constant current output and the peak efficiency without L₀ is about 94%, which is 1% lower than that with L₀. A prototype was built and the experimental results verified the theoretical analysis. Full article

(This article belongs to the Special Issue Wireless Power for Electric Vehicles)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Wireless Power for Electric Vehicles

Share This Special Issue

Special Issue Editor

Special Issue Information

Keywords

Published Papers (8 papers)

Research

Further Information

Guidelines

MDPI Initiatives

Follow MDPI