Selective Activation of Transmitter Coils to Reduce Leakage Magnetic Fields in Wireless Power Transfer Systems with Multiple Transmitters

In wireless power transfer systems, the leakage magnetic field must be kept below a certain specified value, as it can affect the human body or electronic devices in the vicinity. Consequently, many studies have been conducted to reduce the leakage magnetic fields in wireless power transfer systems. This paper aims to minimize the generation of unnecessary magnetic fields by arranging multiple transmitter coils and activating only specific transmitter coils that correspond to the position or size of the receiver coil. It analyzes the magnitude of the current depending on the number of activated transmitter coils and the resulting size of the leakage magnetic field, and discusses a method for selecting transmitter coils to minimize the leakage magnetic field. The proposed method has been verified to reduce the magnetic field by about 53% in a 300 W class WPT system compared to using a single TX.