Research On Efficiency Problem And Transmission Strategy Of Multi-coil Wireless Power Transfer System

Wireless Power Transfer technology has become a hot issue in today’s research because of its high efficiency,reliability,safety and stability,and strong environmental adaptability.Among many Wireless Power Transfer technologies,Magnetic resonance coupling Wireless Power Transfer technology has received extensive attention and research due to its high transmission efficiency and long transmission distance.The magnetic resonance coupling wireless power transfer technology is based on the principle of resonance.The transmission of energy is carried out by using the transmitting coil and the receiving coil to resonate at the power supply frequency.The power transfer efficiency and the quality factor and coupling strength of the coil are important.The relationship,therefore,the multi-coil resonance system that adds coils is also born.However,when using a multi-coil resonance system,the coils are often placed equidistantly,and in fact,the choice of coil position has a large effect on the transmission characteristics of the system.In this paper,the three-coil structure of the wireless energy transmission system is studied from the theoretical analysis,electromagnetic simulation,experimental verification and other aspects.The advantages of the three-coil structure compared with the common two-coil structure are studied.On this basis,the influence of the position of the relay coil on the output power and transfer efficiency of the system is analyzed.Aiming at the efficiency problem,a transmission strategy using the DC-DC converter circuit is proposed,which enables the whole system to adjust the equivalent impedance of the system load when the position of the relay coil is unchanged so that the transfer efficiency is maintained at a higher level.Theoretical analysis and experimental results show that the transmission strategy is not only suitable for the case where the relay coil is fixed and the load resistance changes,and the transfer efficiency can still be maintained when the load is unchanged and the position of the relay coil changes.