Research On Control Methods Against Mutual-inductance Fluctuation Of Orthogonal Receiver For Dynamic Wireless Power Supply

Dynamic wireless power supply(DWPS)technology enables electric vehicles to collect power through the principle of electromagnetic induction during the driving process,which is of great significance for solving the problem of batteries and their charging.Orthogonal receiver coil design could reduce the mutual-inductance fluctuation caused by the driving effect effectively.To ensure reliable and controllable power transmission under dynamic conditions,non-communication-based receiverside output-current control is necessary.Aiming at the DWPS system with bipolar transmitter and orthogonal receiver,this paper focuses on the key issues of receiverside output-current control,and conducts research work from three aspects of testing dynamic operating conditions,coping with the amplitude and frequency of mutualinductance fluctuation.Previously,most of the dynamic condition tests were based on movable platform or real vehicle experiments.They had the disadvantages of high cost,low speed,poor flexibility and controllability.To solve these problems,laboratory test methods for receiver-side control are proposed.The proposed methods lay the foundation for simulation and experimental tests for subsequent research.The circuit architecture of the orthogonal receiver design is introduced,and the two-phase basic circuit structure is given,namely,DQ-phase parallel-connected(DQ-P)and DQ-phase seriesconnected(DQ-S).A circuit simulation model of the magnetic coupler under dynamic conditions is established based on the adjustable inductor,and the accuracy of the model is verified through experiments.A receiver-side-oriented simulator is proposed using receiver-side voltage equivalence.To simulate the full speed range and various mutual-inductance conditions,control scheme for modulating transmitting currents,which is based on LCC network,is demonstrated.The accuracy of the simulator is verified by the movable platform and circuit simulation.Driving trajectory's uncertainty leads to a wide-range change in the relative position of dual-side coils,which causes a large-range mutual-inductance fluctuation.Therefore,the influence of the amplitude of mutual-inductance fluctuation has been studied.For the small mutual-inductance caused by lateral misalignments,DC model of the front wireless power supply and receiver DC-DC converter are combined to establish a cascaded model,and its cascaded stability is analyzed using the Middlebrook criteria.Model analysis and experiments reveals that the cascaded instability problem is prone to occur with small mutual-inductance.For a seriescompensated transmitter with large mutual-inductance,an impedance model is established to study the power limitation,and the mechanism of power limitation caused by the interaction of dual-side converters is analyzed,together with experimental research.Based on the research results under the extreme values of mutual-inductance,system-level design considerations are given.The driving speed directly determines the frequency of mutual-inductance fluctuation,further disturbing output-current control.Hence,the mechanism and suppression method of output-current fluctuation caused by mutual-inductance fluctuation are studied.For the receiver adopting a DQ-S-Buck configuration,output current control and analysis model are established based on the closed-loop audio susceptibility characteristics.Full speed and various mutual-inductance conditions are mainly implemented using the simulator.For the receiver adopting a DQ-P-Boost configuration,an output current reconstruction method is proposed.Based on the closed-loop audio susceptibility characteristics,output current control and analysis model are established to complete the dynamic condition simulation and experiment of direct output control.In order to solve the right-half-plane zero problem of Boost non-minimum phase system,a dual-loop control of output current and a virtual output capacitor ESR control(hereinafter referred to as ESR control)are proposed for DQ-P-Boost respectively.The control scheme and model are also given.The simulation of dynamic conditions and experimental research are completed,and compared with direct output control.It is verified that the proposed high-performance control methods have lower output fluctuation and better transient performance.In high-power DWPS,voltage stress of resonant capacitors easily comes to thousands of volts.Things even gets worse under high-speed conditions.To reduce the overvoltage failure rate of resonant capacitors,the output current control method to suppress the resonant current stress is studied.Based on the closed-loop input admittance characteristics,a current analysis model was established to reveal the excessive current stress of resonant tank at high-speed.For the receiver adopting a DQ-P-Boost,constant resistance(CR)control is proposed.Dynamic experiments are mainly conducted based on the simulator.Discussions on suppressing output fluctuation and improving transient response in practical applications are given,followed by the verification simulation.Then,problem of a receiver adopting a DQS-Buck with CR control is revealed.To tackle this problem,a dual-input Buck(DIBuck)topology is implemented and the DQ-S-DIBuck+CR control system is analyzed.Experiments for testing on dynamic conditions are mainly based on the simulator.It is verified that the proposed solution could mitigate the resonant current stress while ensuring a low output fluctuation.