Design Proposals for Wireless Electrical Power Transmission

Abstract

Wireless power transmission is defined as the ability to transmit electrical energy from a specific voltage source to an electrical load without the use of wires. This study focuses on designing new coils for wireless power transmission, studying and understanding the properties of the magnetic. Additionally, it covers some important aspects of the design process after obtaining practical results and comparing them with theoretical results. After covering these aspects, a complete picture of how these innovative coils should be designed is formed, along with the possibility of modifying the design to improve the efficiency of wireless power transmission.

Introduction

1. Historical Background and Fundamentals

• Hertz first studied radio signals, while Nikola Tesla pioneered wireless energy transmission using resonant coils (transmitter and receiver).

• Tesla showed that magnetic field resonance between two coils enables efficient energy transfer without wires.

• One key limitation is that mutual inductance—the efficiency of energy transfer—decreases with distance between the coils.

2. Development and Renewed Interest

• Interest in WPT grew significantly after research by Soljak and others in magnetic resonance-based energy transfer.

• WPT is now applied in many fields including electric vehicles, smartphones, laptops, and medical implants.

3. Classification of WPT Systems

• A. Short-Range:

  • Typically used in biomedical applications.

  • Power transmission through tissues is limited (e.g., 275 mW over 1 cm).

• B. Medium-Range:

  • Applied in both low- and high-power systems like medical devices and EVs.

  • Efficiency can reach 76% over 1 meter using techniques like harmonic impedance matching.

• C. Long-Range:

  • Uses antennas and EM waves but suffers from very low efficiency.

4. Importance of Coil Design and Alignment

• The shape and orientation of transmitter and receiver coils significantly impact efficiency:

  • Circular coils offer the best coupling coefficient due to uniform magnetic field distribution.

• Misalignment types that reduce performance include:

  • Lateral, angular, elevation, azimuth, rotational, and combined misalignments.

5. Practical Coil Design and Testing

• Different coil designs were tested for inductance and energy transmission performance.

• Two mathematical laws were used to calculate inductance; experimental values validated the more accurate formula.

• Key findings:

  • When coil turns are <10, theoretical inductance must be halved for practical accuracy.

  • When ≥10 turns, theoretical values align closely with practical results.

6. Experimental Wireless Transmission

• Wireless energy transfer occurs via magnetic fields created by AC current in the transmitter coil.

• Resonance between the coils ensures efficient energy transmission.

• Multiple coil types were tested to find those with highest transmission efficiency.

Conclusion

Tesla’s model of resonant loops remains foundational in modern WPT. Efficiency depends heavily on coil geometry, alignment, number of turns, and magnetic coupling. Circular coils perform best, and alignment accuracy is critical in real-world applications like EV charging. Future systems can benefit from optimized coil design, resonant frequency tuning, and precise inductance calculation.

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Copyright

Copyright © 2025 Mohammed Houseen Abdulsalam. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.