Research On The Characteristics Of Wireless Power Transfer System Via Magnetically Coupled Resonance

In recent years, wireless power transfer technology has become a hot research topic, due to its comprehensive application prospects in special situations. In many wireless power transfer technologies, magnetic resonance coupling emerged in recent years. Compared with other conventional wireless power transfer technologies, such as electromagnetic induction and microwave, magnetic resonance coupling attracts more attention, because of its many advantages, for instance, high transfer efficiency in medium transmitting distance, insensitive to misalignment of coils. There are already many research results related to magnetic resonance coupling wireless power transfer technology, but most of them are theoretical and not yet mature. Therefore, before its practical applications, there are many critical issues to be solved, such as, the imperfection of theory and model, the stability when load changes, the electromagnetic interference to surrounding environments, etc.The transfer performance of magnetically coupled resonant wireless power transmission system, such as power, efficiency, etc., will be subject to many factors, and there is also a complex internal relation between various factors. So far, there is no systematic research on the effect laws of various factors on the performance of the transfer system or research on the correlation of factors. Based on the mutual model of magnetic resonance coupling wireless power transfer system, this paper deeply analyzes the impact of various factors on the system, which provides the theoretical foundation to effectively improve the transfer performance of the system.This paper firstly introduces wireless power transmission technology and analysis three of conventional techniques, summarizes the current development of magnetic resonance coupling technology at home and abroad. Then this paper establishes the system models based on coupled mode theory and circuit theory, deeply interprets the inherent energy transfer mechanism of magnetically coupled resonance technology, and analyzes the similarities between the two models. Based on mutual circuit model, this paper analyzes the impact on power and efficiency caused by factors such as the self-resonant frequency, the operating frequency, the change of transmission distance and load, etc. This paper chooses an asymmetric half-bridge inverter and rectangular transfer coils to design a wireless power transfer system that has self-resonant frequency of approximately405kHz and is able to work in the state of ZVS. This system successfully lights a40W bulb at50cm transfer distance. Many experiments are conducted, in order to verify the theoretical analysis; and the experimental results are well consistent with the theoretical analysis.The paper also experimentally investigates the capability of magnetically coupled resonance technique to penetrate obstacle. It proves that the transmission performance is sensitive to metal material barrier; while the energy transfer is not affected by non-metallic barrier due to its strong penetrating capability.