Establishment of ultra-high efficiency microwave wireless power transmission technology for undetectable power receivers in metal housing

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K14730
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 21020:Communication and network engineering-related
• Research Institution: Iwate University
• Principal Investigator: Murata Kentaro 岩手大学, 理工学部, 助教 (20848030)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 無線電力伝送 / マイクロ波 / 空洞共振 / 寄生アンテナ / 電磁遮蔽 / 負荷変調 / Sパラメータ / 整合回路

Outline of Final Research Achievements

This study established a harness-less power-supply technique using radio waves to devices in metal enclosures intended for transportation and industrial machinery.
In the proposed method, the electromagnetic field distribution in the enclosure can be electronically controlled by adjusting the impedance of parasitic antennas with no signal source. By utilizing the unique characteristics of the electromagnetically shielded space and parasitic antennas, an algorithm to indirectly estimate the transfer efficiency was developed, enabling a highly efficient power supply to difficult-to-detect receivers without any feedback.
To demonstrate the proposed method, an automatic impedance control system with extremely low loss (approximately -0.5 dB) and full-range phase controllability was developed, and wireless power transfer with an average transfer efficiency of approximately 50% was demonstrated regardless of the receiving position within the enclosure.

Free Research Field

通信工学

Academic Significance and Societal Importance of the Research Achievements

本邦では、2022年5月に無線給電実用化に向け改正省令が施行され、同技術の市場規模は2031年に約1兆5500億円に達するものと予測されている。一方、電池切れで探知困難なデバイスに対する給電方法は国内外で未だに確立されておらず、同技術普及の律速となっていた。
これに対し提案法では、受電器からのフィードバック不要で約50%の無線給電効率を達成し、上記問題の有効な解決手段となる。提案技術実用化の暁には、ハーネスレス化による輸送・産業機器の軽量・低燃費・低コスト化、電源管理フリー化によるアクセス困難な極限環境における作業ロボットの自立運転支援など、多岐産業分野に渡り波及効果をもたらすことが期待される。