magnetic inductance (MI)
Magnetic induction (MI), also known as magnetic flux density, is a method for wireless power transfer (WPT). Like magnetic resonance( MR), it is based on energy transfer in the magnetic field of a primary coil and a secondary coil.
The efficiency of power transfer depends on many factors of the resonant coils such as their Q-factor, magnetic flux, coupling factor, resonant frequency, coil orientation, coil shape and some others. These factors directly affect the losses and efficiency of energy transfer.
Magnetic induction methods are being standardized and developed by the Power Matters Alliance( PMA) and the Wireless Power Consortium(WPC). This technique can operate over a frequency range between 100 kHz and 300 kHz, but is sensitive and dependent on load impedance. In addition, the distance between the primary and secondary coils should be only a few centimeters.