The effects of operating frequency on wireless power transfer system design and human health in electric vehicles

Abstract

Overview

Wireless power transfer (WPT) systems, used increasingly in scenarios where cable use is challenging, transmit electrical energy through magnetic connections. This paper explores the impact of different operational frequencies on system design and human health in electric vehicles.

Methodology and Key Findings

• Analysis was conducted using WPT systems designed at 10 kHz and 20 kHz frequencies with a 3.3 kW output and dimensions of 50 cm by 50 cm.
• Designs utilized the MATLAB/Simulink and ANSYS® Maxwell 3D programs for circuit and coil design, respectively.
• At 10 kHz with a 15 cm air gap, efficiency reached 88.79%, while at 20 kHz with a 17 cm air gap, it was higher at 92.74%.
• Comparative analysis highlighted distinctions in efficiency, cost, loss, and electromagnetic field distributions between the different frequencies.

Health Implications

Examination of the safety of electromagnetic fields emitted by WPT coils was guided by IEEE and ICNIRP standards. It was discerned that near the coils, particularly between or close to the receiver and transmitter, there is potential harm to human health. At 20 kHz, a safe distance equates to approximately the coil’s diameter away, whereas 10 kHz systems require a greater distance to ensure safety. This underscores the necessity for detection systems to deactivate WPT operations when a living being or object is detected too close to the system.

Conclusion

This study illustrates the crucial balance between operational efficiency and safety considerations in the design of WPT systems for electric vehicles, emphasizing the need for careful consideration of frequency choices and proximity controls to mitigate health risks from electromagnetic fields.