| With the widespread use of electrical energy,there are more and more scenarios where the traditional wired electrical energy transmission methods are not convenient for application,and Wireless Power Transmission(WPT)technology has been selected as one of the top ten future research directions by Technology Review magazine.The technology has been selected by Technology Review as one of the top ten directions for future research.Thanks to its convenience and safety,wireless power transmission devices have become the mainstream power supply for terminal portable mobile devices and new implantable medical devices,but there are problems in wireless transmission such as short distance,small coverage,energy transfer and energy storage.With the in-depth study of materials science,people have been able to recognize more properties of the material itself,and people have used the magnetic characteristics of magnetic materials and some effect-designed electronic components to regulate the magnetic field,which can improve the transmission distance and transmission coverage of WPT technology by means of magnetic field regulation technology and promote its further large-scale application.This paper explores the regulation and application of the magnetic field near the transmitting coil in the electromagnetic induction-coupled wireless energy transmission technology,and the energy characteristics of the electromagnetic waves associated with the electromagnetic radiation-based wireless energy transmission technology,as follows:(1)Investigation of the influence of the magnetic core structure on the magnetic field of the transmitting coil and the design of a new transmitting coil.To investigate the effect of magnetic core structure on the magnetic field in the near field of the transmitting coil by using magnetic materials as the core of the transmitting coil,and to design a new transmitting coil.Compared with the existing launch coils for the same purpose,the fan-loop launch coils are simpler,smaller and more efficient.The work in this paper shows that the new material structure can effectively improve the performance of the transmitting coil.(2)The differences in the energy characteristics of circularly polarized electromagnetic waves and linearly polarized electromagnetic waves are discussed,and specific expressions for the energy characteristics of circularly polarized electromagnetic waves and linearly polarized electromagnetic waves are given.Finally,it is concluded that the energy characteristics of different types of electromagnetic waves may be very different,and the existing energy density expressions that should be used with caution in order to correctly solve the problems related to energy storage and loss.(3)A reasonable calculation scheme for the time-averaged energy density expressions is given.Firstly,it is argued that the energy storage of electromagnetic waves is oscillating periodically,and according to the law of energy conservation and causality,the energy storage should be stored first and then released,so the time-averaged energy density expression is positive definite.On this basis,the time-averaged energy density expression for a linearly polarized electromagnetic wave propagating in a linearly isotropic medium can be obtained by choosing an appropriate onset time to calculate the time-averaged value of the stored energy density.These works can provide a clear physical picture and physical meaning for the time-averaged energy density expressions and may help to further solve the energy transfer-related problems. |
