Towards free-positioning self-adaptive wireless power transfer systems

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School of Electrical Engineering | Doctoral thesis (article-based) | Defence date: 2025-01-10
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Authors

Date

2024

Department

Sähkötekniikan ja automaation laitos
Department of Electrical Engineering and Automation

Major/Subject

Mcode

Degree programme

Language

en

Pages

84 + app. 62

Series

Aalto University publication series DOCTORAL THESES, 272/2024

Abstract

The quest for achieving wireless power transfer (WPT) over a large area to facilitate the charging of multiple devices has given rise to numerous challenges, particularly concerning the free positioning charging freedom of the receiver anywhere in a large area. Addressing these challenges, this doctoral dissertation proposes and validates several innovative solutions and methods for enhancing the performance and robustness of large-area WPT systems. One of the primary obstacles in the WPT system is the deterioration of performance as the receiver's position and characteristics change. This necessitates the observation of load resistance and receiver position to enable effective power transfer. This dissertation focuses on a data-driven approach to estimate WPT system characteristics to ensure effective power transfer. The machine learning assisted approach presented in the dissertation only relies on the transmitter-side measurements. This method differentiates between low and high system efficiency which assists in deciding turn-on and -off transmitters in multi-transmitter WPT systems. Additionally, the dissertation presents a method aimed at efficient positioning-free wireless power transfer over a considerably large area. This is achieved via a novel transmitter arrangement within a pad-like area, thereby assuring unbroken paths for magnetic flux for effective power transfer. The dissertation also introduces an innovative technique for the activation and deactivation of the transmitters based on the position and rotation of the receiver, using only the measurements taken from the transmitter side. This is a crucial element for the future implementation of high-efficiency and cost-effective dynamic wireless power transfer devices. This strategy eliminates the need for any additional sensors or data communication, leading to potential applications in the wireless charging of industrial robots and drones. In this dissertation, a planar receiver structure comprising three coils is presented, which enables unimpeded positioning within the designated transmitting zone, thereby sidelining the necessity for intricate control mechanisms or the tracking of receiver positioning. This revolutionary design for the receiver ensures a consistent rate of efficiency across the entirety of the WPT area. In addition, the dissertation discusses the coil design while also demonstrating how to optimize the volume and shape of the magnetic materials employed in WPT transmitters. Finally, this dissertation puts forth a novel methodology for coil activation in multi-transmitter wireless power transfer systems, thus providing complete flexibility in receiver positioning over a large area. This non-coherent power combining method eliminates power transfer blind spots and exhibits a steady DC-DC power transfer efficiency of approximately 90%, irrespective of arbitrary receiver movements, and dispenses with the necessity for any additional dynamic controls.

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Supervising professor

Kyyrä, Jorma, Prof., Aalto University, Department of Electrical Engineering and Automation, Finland

Thesis advisor

Jayathurathnage, Prasad, Dr., Danfoss Drives, Finland

Keywords

wireless power transfer, free-positional wireless charging, large area wireless power transfer, full freedom of wireless charging

Other note

Parts

  • [Publication 1]: S. A. Al Mahmud, P. Jayathurathnage and S. A. Tretyakov. Machine Learning Assisted Characteristics Prediction for Wireless Power Transfer Systems. IEEE Access, vol. 10, pp. 40496-40505, April 2022.
    Full text in Acris/Aaltodoc: https://urn.fi/URN:NBN:fi:aalto-202205173246
    DOI: 10.1109/ACCESS.2022.3167162 View at publisher
  • [Publication 2]: S. A. Al Mahmud, I. Panhwar and P. Jayathurathnage. Large-Area Free-Positioning Wireless Power Transfer to Movable Receivers. IEEE Transactions on Industrial Electronics, vol. 69, no. 12, pp. 12807-12816, January 2022.
    Full text in Acris/Aaltodoc: https://urn.fi/URN:NBN:fi:aalto-202209145606
    DOI: 10.1109/TIE.2022.3144591 View at publisher
  • [Publication 3]: S. A. Al Mahmud, P. Jayathurathnage, Y. Liu, J. Kyyra and S. Tretyakov. A New Receiver Detection and Fast System Activation Method for Wire­ less Power Transfer. In 2023 IEEE Wireless Power Technology Conference and Expo (WPTCE), San Diego, CA, USA, 2023, pp. 1-5, June 2023.
    DOI: 10.1109/WPTCE56855.2023.10216229 View at publisher
  • [Publication 4]: Y. Liu, S. A. Al Mahmud, N. H. Van, P. Jayathurathnage, J. Kyyra, and S. A. Tretyakov. Noncoherent Power Combining for Free-Positioning Wireless Power Transfer in Large Area.
    Full text in Acris/Aaltodoc: https://urn.fi/URN:NBN:fi:aalto-202404113040
    DOI: 10.1109/TIE.2024.3374391 View at publisher
  • [Publication 5]: S. A. Al Mahmud, N. H. Van, Y. Liu, P. Jayathurathnage, and S. A. Tretyakov. Planar Free-Positioning Wireless Power Transfer System for Industrial and Automotive Robotic Applications. Submitted to IEEE Open Journal of the Industrial Electronics Society, August 2024.
    DOI: 10.36227/techrxiv.172253771.14282277/v1 View at publisher

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https://urn.fi/URN:ISBN:978-952-64-2186-5

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[diss] Sähkötekniikan korkeakoulu / ELEC