| Electric vehicle dynamic wireless charging(EVDWC)technology can realize charging while the electric vehicle(EV)is moving.In recent years,EVDWC technology has attracted the attention of many scientific research institutions at home and abroad because it is conducive to promoting the development of intelligent roads and solving the anxiety problem of EV cruising range,which is a cutting-edge hot technology direction.However,in the process of dynamically picking up power by the receiving coil equipped on the EV,the change of the relative position between the receiving coil and the transmitting coils and the switching of the adjacent ground transmitting coils will cause the equivalent mutual inductance between the transmitting coils and receiving coil to change,which results in unstable system output power.The output power fluctuation during the EV traveling process is mainly caused by rail switching and lateral offset,which may lead to problems such as insufficient power picked up at the vehicle receiver,unstable charging process of the power battery,and reduced safety.Aiming at this problem,the existing literature mainly focuses on the shape of the magnetic coupler,the control strategy or the multi-phase current excitation,and the impedance matching network.However,the existing methods cannot be an ideal solution due to the limitations of the universal requirements and implementation difficulty of EVDWC systems,the order and complexity of the system,the fast movement of EVs,and the effect of suppressing power fluctuation.Therefore power fluctuation suppression urgently needs new solutions.The source of the power stability problem is the change in the magnetic field and the magnetic coupling parameters.Through the magnetic integration technology,additional coupled inductor coils are placed in the magnetic coupler of the wireless power transmission system,and the magnetic path is shared with the transmitting coil or the receiving coil.The magnetic coupling parameters are mapped into the circuit model,which is expected to increase the system power density and improve the power transfer characteristics.Existing research on magnetic integration technology for wireless power transfer systems focuses on static systems with a single transmitter and a single receiver.It is urgent to seek new solutions from the perspective of magnetic integration technology and to study the method for suppressing power fluctuation in EVDWC systems,realizing the power smoothness during the EV traveling process.However,the working state of the EVDWC system is particularly complex.With the constant change of the coupling parameters when the EV moves on the road,multiple time-varying magnetic coupling parameters complicate the working and output characteristics of the system and make the system modeling and transmission characteristics analysis more difficult.In addition,the comprehensive performance of the system includes the working states of EVs at multiple locations,and the relationship between the geometric scale parameters and the electrical performance of the system is not yet clear.Focusing on the power stationarity problem of EV traveling in EVDWC systems,this thesis studies the magnetic integration method for power fluctuation suppression.The innovative research work of this thesis is mainly reflected in:(1)To explore the application method of magnetic integration technology in the EVDWC system,the magnetic integration mechanism and characteristics of the LCCLCC wireless power transfer system are analyzed.Focusing on the resonant compensation inductive-magnetic integration method and the power-coil compound inductive-magnetic integration method,the function of the integrated coil in the circuit model is analyzed from the overall level,and its influence mechanism on the power transmission characteristics is revealed.Aiming at the three working modes of resonance compensation inductor magnetic integration,the working principle of the LCC-LCC wireless power transfer system with magnetic integration coupler is analyzed,and the output power characteristics and system performance under different working modes are studied.The characteristics and working principle of the integrated composite inductor coil in reverse series are analyzed,and the output characteristics and application methods of using the mutual inductance difference to transfer power are studied.Studies have shown that magnetic integration technology can effectively improve the output characteristics and working performance of the system based on making the system more compact.(2)From the perspective of improving the power transfer capability at the guide rail switching position,and focusing on the output power fluctuation caused by the guide rail switching in the EVDWC system,an LCC-LCC compensation inductor magnetic integration method based on dual-channel power transmission is proposed,with a new power transmission channel constructed for compensating the power drops at the switching position of the rail.Combined with the magnetic integrated coupler,a composite LCC resonant network topology with a series part is proposed,and the matching rule for resonant parameters considering additional cross-coupling is given.Research shows that this method realizes the smooth switching of guide rails based on the normal operation of the system,without additional control or adding new components.Through the 12-k W EVDWC system prototype experiment with single-coupling compensation inductor magnetic integration,the power output fluctuate within ±4%during the movement of the receiving coil is realized,and the maximum DC-DC efficiency of the system reaches 92.3%.(3)From the perspective of optimizing power transmission mode,focusing on the output power fluctuation problem caused by rail switching in the EVDWC system,a magnetic integration method of LCC-LCC reverse winding based on mutual inductance difference for power transfer is proposed,which converts the output power fluctuation suppression problem into the design of a stable equivalent mutual inductance between the receiving coil and an array of transmitting coils on the road.In addition,a multi-coupled resonance compensation inductor magnetic integration method is proposed to optimize the zero voltage switching(ZVS)condition.The influence characteristics of the integrated reverse coil on the equivalent mutual inductance in the EVDWC system are analyzed,and the functional relationship between the phase angle of the input impedance and the magnetic coupling parameters of the integrated compensation inductance coil is deduced.The research shows that this method optimizes the power transmission mode,and smoothes the equivalent mutual inductance in the EVDWC system by converting a single mutual inductance into a mutual inductance difference for power transmission.Through the 4.5-k W EVDWC system prototype experiment with magnetic integration of reverse windings in series,the power output fluctuates within ±4% during the movement of the receiving coil,and the system DC-DC efficiency reaches 91.6%.The output of the converter maintains optimized ZVS working conditions.(4)Based on the research in the previous chapters,from the perspective of compensating the power drop during lateral offset,and focusing on the output power fluctuation during EV traveling in the EVDWC system,an LCC-LCC variable inductor magnetic integration based on the same-side internal coupling is proposed.The method uses a small DC to realize the compensation of the system output power drop.A planar variable integrated inductor coil is proposed,and the correlation characteristics between its magnetic coupling parameters and the parameters of the same-side internal coupling circuit are explored.Its working principle is analyzed,and the current excitation mode and parameter design criteria are given.The research shows that this method,combined with the proposed planar variable integrated inductor,utilizes the same-side internal coupling to realize the output power fluctuation suppression during EV traveling in the EVDWC system.Through the prototype experiment of a 4.5-k W EVDWC system with magnetic integration of the variable inductor,the power output fluctuates within ±5%during the movement of the receiving coil under a 10 cm lateral misalignment state was achieved,and the system DC-DC efficiency reached 90.6%.The inverter output maintains the optimized ZVS working condition.The research in this thesis explores the magnetic integration method of EVDWC system power fluctuation suppression,realizes the power stability during EV traveling,and helps to promote the development of EVDWC technology and the application of EV. |
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