| The magnetic resonance coupling wireless power transfer technology has a significant advantage over traditional electromagnetic induction mode in long transfer distance,which is currently a research hotspot in the field of wireless power transfer.It has broad application prospects in industrial equipment,biomedical,military and other fields.Take the information interaction between the fuze and the weapon system in military field for example,the wireless power transfer technology is used to power the fuze circuit before the projectile is launched,and circuit module is activated to receive initial control information such as battlefield environment information and target information captured by weapon platform.It is the key technology to improve the damage efficiency of ammunition.However,this application environment is different from the air wireless transfer environment where the transmitter and receiver are relatively static.It needs further research on the relevant basic theory and technical methods to provide wireless power more efficiently to the motion fuze under the influence of metal.Based on the application environment characteristics of magnetic resonance coupling wireless power transfer technology in the fuze information interaction,the related basic theory and performance optimization method are studied.Basic theory of wireless power transfer in air environment is clarified.The optimization methods of power dynamic transfer performance under relative radial motion of transmitter and receiver are studied.The influence of metal environment on coil parameters and power transfer performance is revealed,and the magnetic resonance information interaction prototype is developed to verify the correctness of the theory and the feasibility of the technical scheme.The basic theory of magnetic resonance coupling wireless power transfer in air environment is studied.The theoretical models of magnetic resonance coupling wireless power transfer system under non-pure resistive load or multi-load conditions are established.The influence rule of load impedance characteristics and cross-coupling between loops on resonance frequency and power transfer characteristics is revealed.The reactance component in the load impedance will cause the resonance frequency offset and adversely affect the transmission performance.The fundamental reason is that the load impedance changes the equivalent capacitance or inductance value of the relay circuit through coupling mapping.When the load impedance angle is less than zero,the resonance frequency decreases compared with the pure resistance.With the increase of the impedance angle,the frequency offset and its influence on transfer performance gradually weakens.The opposite is true if impedance angle is greater than zero.In addition,if the load impedance angle is the same,the transfer performance of the system is the same regardless of the reactance component.The cross-coupling between transmitter and receiver during multi-load transmission also causes resonance frequency offset and even changes the resonance frequency bifurcation characteristics.In order to improve the power transfer performance and overcome the influence of the operating frequency points of power and efficiency don't coincide and load fluctuation,an optimization control method of power efficiency in transfer process and an optimization design method based on impedance matching network are proposed.In view of the fact that operating frequency points of the peak power and the peak efficiency do not coincide with each other,the load modulation technology is used to feedback the working state of the receiver to the transmitter in real time,and to control the power transfer process in a closed loop way,so as to realize the tracking or adjustment between peak power and peak efficiency.To realize impedance matching between the receiver and transmitter and reduce the negative impact of load impedance fluctuation or reactance components,two optimization measures based on unilateral matching at the receiver and bilateral matching at both the transmitter and the receiver are proposed.It is pointed out that T-type unilateral matching has advantages in improving transfer efficiency and transfer performance of systems with large reactance load,while L/T-type bilateral matching is more suitable for transfer power optimization of systems with pure resistive load or small reactance load.The fast and reliable wireless power transfer method under the condition of relative radial motion of the transmitter and receiver is studied.Considering the complexity and accuracy of the model,the mutual inductance calculation models of two circular spiral coils,rectangular and circular spiral coils with parallel axes are established.The experimental results show that the model error is within ±5%.It is pointed out that when the parameters of the receiving end coil are fixed,the effective power transfer area under the radial motion of the transmitter and receiver can be broadened by increasing the diameter of the transmitting coil properly,and with the increase of transfer distance,the diameter ratio will increase.When the transmitter and receiver coils are coaxial,the circular spiral coil has a larger coupling coefficient under the same area,but the rectangular spiral coil is more insensitive to the radial offset,which can obtain a comparatively or even slightly better power transfer performance.The calculation model of coil scattering field impedance and the wireless power transfer model under the influence of metal environment are established,and the influence rule of metal environment on coil parameters and power transfer performance is revealed.The formula for calculating the scattering field impedance of coils in metal cylinders is deduced.It is pointed out that when there are metal objects around the transfer channel,the equivalent resistance value of coils increases and the inductance value decreases,and the increase of coil resistance value caused by ferromagnetic metal materials is more than that caused by non-ferromagnetic metal materials,while the decrease of inductance value is less.A theoretical model of wireless power transfer under the influence of metal objects is established.It is pointed out that the transfer characteristics of power and efficiency under the influence of metal environment have the similar characteristics of air environment,and the resonance frequency will increase,while the transfer performance will generally decrease compared with that in air environment.The fundamental reason of the transfer performance change is that the eddy current parameters will result in variations in the system equivalent parameters,including equivalent impedance of system and load.The information synchronization fast loading method in power transfer channel based on non-return-to-zero amplitude modulation is proposed.A fuze magnetic resonance coupling wireless information interaction prototype is designed.The static test in laboratory,the dynamic recovery test and projectile detonation test of the shooting range prove that the designed information interaction system can reliably supply power and transmit control information to the motion fuze under the influence of metal environment of weapon platform,and the dynamic interaction speed is about 120 ms per projectile.The fuze magnetic resonance couplingcartridge link dynamic information interaction system based on the theory and technical scheme designed in this paper has been applied in a small caliber air-burst blast-mentation munition project. |
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