Study Of Compensation Topology Design For Inductive Power Transfer System Considering Coils’ Parameters Variations

With the accelerated pace of urbanization in China,more and more electrical equipment is being used for people’s production and life.Traditional wired or plugin power supply systems have revealed many drawbacks.Inductive power transfer(IPT)technology can transfer electrical energy from a power source to a consumer device in a non-physical manner.With the advantages of flexible power supply and no contact sparks,IPT technology has been widely studied and applied in recent years in the fields of electric vehicles and automated guided vehicles.IPT technology transmits energy through electromagnetic induction between the coupling mechanism’s transmitting coil and pickup coil.The output stability problem caused by the displacement of the coupling coils is one of the main problems limiting the development of IPT technology applications.In the practical application of IPT systems,variations in the height of the pickup coil due to changes in the load of the electrical equipment and tire deformation are inevitable.It can cause the system coils’ parameters(self-inductances and mutual inductance)to change,further affecting the stability of the system output.Most of the currently available methods for improving the misalignment tolerance of IPT systems assume constant coil self-inductance.They cannot meet the power supply needs of increasingly flexible power-using devices.Therefore,research into an IPT system with stable output characteristics when the coils’ parameters change is an urgent need for the development of IPT technology applications.In order to solve the above problems,this paper proposes a compensation topology design method for IPT systems that takes into account the variations of coils’ parameters.Through the study of the variation’s rules and characteristics of the coils’ parameters,the reason for the variations of the coil parameters are analyzed,and a multivariate normalized mathematical description of the coils’ parameter fluctuations is established.To find the applicable compensation topology and parameters for IPT systems considering coils’ parameters variations,a unified mathematical model of the compensation topology of IPT systems considering coils’ parameters variations is established in this paper,which takes into account the four basic compensation topologies of IPT systems.And the relationship between the compensation topology and the input and output characteristics such as the IPT system’s transmission power,output voltage/current,and the input impedance is investigated.At the same time,in order to maintain high efficiency and low component cost in the detuned state,the causes of system power loss and component cost are analyzed and calculated in this paper.Then,in light of the above model,this paper proposes a compensation topology design method for IPT systems considering the variations of coils’ parameters based on the non-dominated sorting genetic algorithm-II.The method proposed in this paper is further illustrated and iteratively modified through arithmetic examples and experiments.Finally,to verify the effectiveness of the method proposed in this paper,three sets of experimental prototypes of IPT systems with different output characteristics(constant power,constant current,and constant voltage)were built.The experimental results show that the system output fluctuates only 3.55%～5.63%,and the system efficiency reaches 84.6% to 96.52%when the coils’ parameters of different coupling mechanisms are changed within the set height variation range.