Separation-Independent Wearable 6.78 MHz Near-Field Radiative Wireless Power Transfer using Electrically Small Embroidered Textile Coils
Achieving a wireless power transfer (WPT) link insensitive to separation is a key challenge to achieving power autonomy through wireless-powering and wireless energy harvesting over a longer range. While coupled WPT has been widely used for near-field high-efficiency WPT applications, the efficiency...
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| Format: | Article |
| Language: | English |
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MDPI AG
2020-01-01
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| Series: | Energies |
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| Online Access: | https://www.mdpi.com/1996-1073/13/3/528 |
| _version_ | 1811301698838200320 |
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| author | Mahmoud Wagih Abiodun Komolafe Bahareh Zaghari |
| author_facet | Mahmoud Wagih Abiodun Komolafe Bahareh Zaghari |
| author_sort | Mahmoud Wagih |
| collection | DOAJ |
| description | Achieving a wireless power transfer (WPT) link insensitive to separation is a key challenge to achieving power autonomy through wireless-powering and wireless energy harvesting over a longer range. While coupled WPT has been widely used for near-field high-efficiency WPT applications, the efficiency of the WPT link is highly sensitive to separation and alignment, making it unsuitable for mobile systems with unknown or loose coupling such as wearables. On the other hand, while ultra-high frequency (UHF) and microwave uncoupled radiative WPT (0.3−3 GHz) enables meters-long separation between the transmitter and the receivers, the end-to-end efficiency of the WPT link is adversely limited by the propagation losses. This work proposes radiative WPT, in the 6.78 MHz license-free band, as a hybrid solution to separation-independent WPT, thus mitigating the losses associated with coil separation. Resonant electrically small antennas were fabricated using embroidered textile coils and tuned using L-matching networks, for wearable WPT. The antenna’s efficiency and near-fields have been evaluated numerically and experimentally. The proposed WPT link achieves a stable forward transmission of S<inline-formula> <math display="inline"> <semantics> <mrow> <msub> <mrow></mrow> <mn>21</mn> </msub> <mo>></mo> <mo>−</mo> <mn>17</mn> </mrow> </semantics> </math> </inline-formula> dB and S<inline-formula> <math display="inline"> <semantics> <mrow> <msub> <mrow></mrow> <mn>21</mn> </msub> <mo>></mo> <mo>−</mo> </mrow> </semantics> </math> </inline-formula>28 dB, independent of coil separation on the XZ and XY planes respectively, in a 27 m<inline-formula> <math display="inline"> <semantics> <msup> <mrow></mrow> <mn>3</mn> </msup> </semantics> </math> </inline-formula> volume space. The presented approach demonstrates the highest WPT link efficiency at more than 1-m separation and promises higher end-to-end efficiency compared to UHF WPT. |
| first_indexed | 2024-04-13T07:13:21Z |
| format | Article |
| id | doaj.art-770acec9bbb0485d925263eff6e0aa0e |
| institution | Directory Open Access Journal |
| issn | 1996-1073 |
| language | English |
| last_indexed | 2024-04-13T07:13:21Z |
| publishDate | 2020-01-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Energies |
| spelling | doaj.art-770acec9bbb0485d925263eff6e0aa0e2022-12-22T02:56:48ZengMDPI AGEnergies1996-10732020-01-0113352810.3390/en13030528en13030528Separation-Independent Wearable 6.78 MHz Near-Field Radiative Wireless Power Transfer using Electrically Small Embroidered Textile CoilsMahmoud Wagih0Abiodun Komolafe1Bahareh Zaghari2School of Electronics and Computer Science, University of Southampton, Southampton SO17 1BJ, UKSchool of Electronics and Computer Science, University of Southampton, Southampton SO17 1BJ, UKSchool of Electronics and Computer Science, University of Southampton, Southampton SO17 1BJ, UKAchieving a wireless power transfer (WPT) link insensitive to separation is a key challenge to achieving power autonomy through wireless-powering and wireless energy harvesting over a longer range. While coupled WPT has been widely used for near-field high-efficiency WPT applications, the efficiency of the WPT link is highly sensitive to separation and alignment, making it unsuitable for mobile systems with unknown or loose coupling such as wearables. On the other hand, while ultra-high frequency (UHF) and microwave uncoupled radiative WPT (0.3−3 GHz) enables meters-long separation between the transmitter and the receivers, the end-to-end efficiency of the WPT link is adversely limited by the propagation losses. This work proposes radiative WPT, in the 6.78 MHz license-free band, as a hybrid solution to separation-independent WPT, thus mitigating the losses associated with coil separation. Resonant electrically small antennas were fabricated using embroidered textile coils and tuned using L-matching networks, for wearable WPT. The antenna’s efficiency and near-fields have been evaluated numerically and experimentally. The proposed WPT link achieves a stable forward transmission of S<inline-formula> <math display="inline"> <semantics> <mrow> <msub> <mrow></mrow> <mn>21</mn> </msub> <mo>></mo> <mo>−</mo> <mn>17</mn> </mrow> </semantics> </math> </inline-formula> dB and S<inline-formula> <math display="inline"> <semantics> <mrow> <msub> <mrow></mrow> <mn>21</mn> </msub> <mo>></mo> <mo>−</mo> </mrow> </semantics> </math> </inline-formula>28 dB, independent of coil separation on the XZ and XY planes respectively, in a 27 m<inline-formula> <math display="inline"> <semantics> <msup> <mrow></mrow> <mn>3</mn> </msup> </semantics> </math> </inline-formula> volume space. The presented approach demonstrates the highest WPT link efficiency at more than 1-m separation and promises higher end-to-end efficiency compared to UHF WPT.https://www.mdpi.com/1996-1073/13/3/528coilswireless power transferelectrically small antennase-textilesinternet of thingswireless energy harvesting |
| spellingShingle | Mahmoud Wagih Abiodun Komolafe Bahareh Zaghari Separation-Independent Wearable 6.78 MHz Near-Field Radiative Wireless Power Transfer using Electrically Small Embroidered Textile Coils Energies coils wireless power transfer electrically small antennas e-textiles internet of things wireless energy harvesting |
| title | Separation-Independent Wearable 6.78 MHz Near-Field Radiative Wireless Power Transfer using Electrically Small Embroidered Textile Coils |
| title_full | Separation-Independent Wearable 6.78 MHz Near-Field Radiative Wireless Power Transfer using Electrically Small Embroidered Textile Coils |
| title_fullStr | Separation-Independent Wearable 6.78 MHz Near-Field Radiative Wireless Power Transfer using Electrically Small Embroidered Textile Coils |
| title_full_unstemmed | Separation-Independent Wearable 6.78 MHz Near-Field Radiative Wireless Power Transfer using Electrically Small Embroidered Textile Coils |
| title_short | Separation-Independent Wearable 6.78 MHz Near-Field Radiative Wireless Power Transfer using Electrically Small Embroidered Textile Coils |
| title_sort | separation independent wearable 6 78 mhz near field radiative wireless power transfer using electrically small embroidered textile coils |
| topic | coils wireless power transfer electrically small antennas e-textiles internet of things wireless energy harvesting |
| url | https://www.mdpi.com/1996-1073/13/3/528 |
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