Research On Power Characteristics Of Magnetic Coupling Resonance Wereless Power Transmission

Wireless power transmission technology refers to the technology of non-contact power transmission through soft media such as space electric or magnetic fields.Compared with the traditional power transmission method,this method has the advantages of safety,reliability,and convenience.In recent years,wireless power transfer(Wireless Power Transfer,WPT)technology is mainly used in electric vehicles,small electronic devices,and implantable electronic devices in the body.Due to the high transmission power of the magnetic coupling resonance type at medium distances,it has become a research hotspot in recent years.In the WPT system,due to load changes,transmission distance changes,and coupling coil offsets,the mutual inductance changes,leading to system detuning.When the system is working in a detuned state,the output power of the system is small,the power factor is low,and the large reactive power loss will reduce the transmission efficiency of the system.Therefore,the research on detuning control of WPT system is of great significance.This article is based on the background of wireless charging of mobile phones.The charging device and the transmitting coil for wireless power transmission are generally fixed on the desktop or the charging disc,and the coil on the receiving side is built into the mobile phone.Because the charging position of the device will be offset every time,the system will deviate from the inherent resonance parameters.Detuned working conditions.In order to enable the offset system to have the maximum output power and relatively high transmission efficiency,it is necessary to perform frequency tracking control on the system.This article first introduces the principle of magnetic coupling resonance wireless power transmission,uses mutual inductance theory to model,calculates and derives circuit parameters of different compensation topologies,and analyzes the causes of detuning.Secondly,the relationship between the three parameters of frequency,load and transmission distance and transmission power is studied.Then the differential quadrature phase lock method is used to actively track the current of the system,and the phase compensation control link is improved.By using two derivative elements(Derivative Element DE)to construct a quadrature signal,the phase can be accurately identified and the phase lock function can be realized.The phase detector does not rely on frequency feedback,avoids the oscillation caused by the feedback frequency,and has better phase lock accuracy and dynamic performance.A MATLAB simulation model was established to verify the rationality of the improved differential control strategy and parameter design.Finally,a test prototype of the WPT system is built and experiments are carried out.The experimental results verify the feasibility of the improved control method and the correctness of the parameter design.