Expanding Exposure Area of Magnetic Field Generator for Biological Evaluation by using Dual Air-Core Inductor

Recently, wireless power transfer(WPT) systems for electrical vehicles in 85 kHz band have gained lots of attention as the charging method. However, human exposure is concerned due to the leakage magnetic field because WPT systems are installed in proximity to the human body. Therefore, it is required to evaluate the biological effects induced by the magnetic field through the experimental verification for mice. A magnetic field generator which consists of a single-phase inverter and an LC resonant circuit has been already proposed for evaluating the biological effects, and a magnetic field generator, that comprises dual voltage source inverter and dual air-core coil, has been also proposed. This paper discusses expanding exposure area for the magnetic field generator, that comprises dual air-core inductor which two inductors are arranged in proximity, to perform the exposure experiment for multiple subjects simultaneously. Analysis of impedance frequency characteristic is discussed by focusing on the mutual inductance of dual air-core inductor in case the circuit parameters of the RLC resonant circuit for each inverter are asymmetry. The magnetic field distributions of two inductor structures are presented, and it is confirmed that the proposed magnetic field generator can expand the magnetic intensity range compared with the conventional magnetic field generator. Moreover, the validity of impedance and inverter operation analyses for proposed circuit is confirmed through the experimental verification rated at 150 V.