Control of Alternating Magnetic Field Distribution Using Twin Coils and Dual-Voltage Source Inverters to Realize High-Performance Biological Evaluation

Recently, wireless power transfer (WPT) systems for electrical vehicles in the 85 kHz band have gained significant attention. However, human exposure due to the leakage magnetic field is a growing concern because WPT systems are installed in proximity to the human body. Therefore, it is essential to evaluate the biological effects induced by magnetic fields through experimental verification. To address this issue, a magnetic field generator was proposed for evaluating biological effects. A magnetic field generator must generate a higher alternating magnetic field. In addition, the biological experiments for sham exposure are conducted simultaneously under zero magnetic field conditions to perform control experiments. Therefore, it is preferable to provide a zero magnetic field environment under the same environment with exposure experiment except the magnetic field. This article proposes a magnetic field generator that consists of twin air-core coils and dual-inverter circuits that can produce either a higher or lower magnetic field at 85 kHz on the same system configuration. The analysis of the inverter circuit operations for in-phase and opposite phase is presented. Moreover, the validity of operation analysis for the proposed circuit is confirmed through the experimental verification of 1/10 current scale.