| Magnetic coupled inductive power transfer(IPT)technology originated from a century ago,and has become one of the research hotspots in the field of power electronics.Maximum power and maximum efficiency represent the power transmission capacity and power utilization efficiency of the IPT system respectively.It is the two key index to determine the performance of the system.However,previous studies show that the system can not track the maximum power and maximum efficiency simultaneously,and the tracking mode of the system must be selected according to the actual requirements.There are some issues in the current researches,such as: the limited tracking load redundancy due to the limited impedance matching range;the tracking failure caused by the unknown coupling coefficient;the poor tracking performance caused by the improper signal transmission method.To a certain extent,these problems restrict the practical application of maximum power tracking and maximum efficiency tracking.This paper firstly analyzes the conditions of maximum power and maximum efficiency tracking.And then presents a tracking control architecture based on active impedance matching.Aiming at the problem of load adaptability in the tracking process,an impedance matching range extension method based on the dual working mode of the active impedance matching converter is proposed.Aiming at the problem of coupling coefficient fluctuation adaptive in power transmission process,a dynamic coupling coefficient identification method based on intrinsic tracking topology is proposed.For the problem of information interaction in the tracking process,we propose a parallel transmission method of power and signal,which power is transferred by magnetic field,while signal is transferred by electric field.Specifically,the main research work in this paper is as follows:1.Aiming at the maximum power tracking and maximum efficiency tracking based on impedance matching,the impedance model of IPT system is constructed,and the optimal load condition of maximum power point tracking and maximum efficiency tracking is deduced.Furthermore,the commonly used impedance matching circuit in tracking process is given.According to the topology of different impedance matching circuits,the impedance transformation relations are studied,the general design method of the controllable parameters of the impedance matching circuit is derived,and the control mechanism of maximum power tracking and maximum efficiency tracking based on impedance matching is given.2.Aiming at the failure of maximum power tracking and maximum efficiency tracking caused by the limited impedance matching range.In this paper,the reason why the impedance matching range is limited is analyzed,and a method of expanding the impedance matching range by switching the working mode of the DC/DC converter is proposed.According to the voltage transfer model of DC/DC converter under current continuous mode and current discontinuous mode,two impedance models are established,and the widening load adaptation range by switching two working modes is obtained.On this basis,a control strategy of maximum power tracking and maximum efficiency tracking based on the impedance matching range extension method is presented,which achieves the tracking under a wide load variation range.3.Aiming at the failure of maximum power tracking and maximum efficiency tracking caused by the unknown coupling coefficient.In this paper,the reason of the failure is analyzed in detail,and a dynamic coupling coefficient identification method based on the inherent tracking topology is proposed.Because there is a two value problem when identifying the coupling coefficient through the secondary side electrical parameters of the IPT system,a strategy to solve the two value problem and estimate the real coupling coefficient is proposed.The control structure and working flow chart of the coupling coefficient adaptive maximum power tracking and maximum efficiency tracking are given.Simulation and experiment results have verified the feasibility of the proposed coupling coefficient identification method,and the maximum power point tracking and maximum efficiency tracking strategy.4.Aiming at the maximum power tracking and maximum efficiency tracking based on the information interaction.In this paper,a signal transmission method by the parasitic capacitances between metal plate and coupling coil is proposed.On this basis,the output voltage control strategy is given.A dynamic coupling coefficient identification method based on increment expression is proposed,and the control flow for maximum power tracking and maximum efficiency tracking is analyzed.Both the simulation and the experiment results have verified the feasibility of the proposed signal transmission method and the correctness of the coupling coefficient identification.The maximum power tracking and maximum efficiency tracking are realized with the constant output voltage and the dynamic coupling coefficient identification. |
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