Research On Inductive Wireless Charging System With Configurable Charging Current

In the wireless power transmission(WPT)technology,Inductive Power Transfer(IPT)technology is a new power supply technology that utilizes kHz-MHz alternating magnetic field for non-contact power transmission.The application of IPT technology to the battery charging field of electric bicycle(EB)solves the safety hazards such as electric shock,electric leakage and electric spark in the traditional charging mode by utilizing the advantages of flexible power supply,safety,high stability and strong environmental affinity.At present,all of the IPT charging system realized by the circuit topology method can be used for EB chargeng.However,under the premise of sharing the charging pile,the system charging current cannot be changed by the configuration parameters,and it is difficult to use for the EB of different specifications(different charging current).In addition,the coupling mechanism of the existing circuit topology IPT charging system is two coils,and the IPT system using a multi-coil coupling mechanism such as a three-coil or a four-coil cannot achieve constant current output,and cannot safely and stably charge the battery.In order to solve the above problems,two new structures are proposed based on the two-coil coupling mechanism and the three-coil coupling mechanism.Combined with the output current and voltage characteristics of the LCL and SS compensation circuits and the input impedance characteristics,the circuit topology of the charge current configurable IPT charging system based on the two-coil coupling mechanism is given,and the charging mode switching method that two switches and one additional capacitor are added in the secondary circuit is proposed,realize that a single inverter could charges a plurality of EBs and EBs with different charging currents can share the charging pile and the system has no reactive power input.Finally,the circuit parameter design method of the charging system is given,and the circuit simulation model and experimental prototype of the 48V-2A and 48V-4A charging systems in parallel are built.In the experiment,in constant current charging,the change rate of the 4A system of charging current is 0.35%,and the maximum efficiency is 88.65%;in constant voltage charging,the change rate of the 4A system of the charging voltage is 5.6%,and the maximum efficiency is 91.32%;the charging mode switching process is smooth;2A system and 4A system can work normally at the same time in parallel with a single inverter.Simulation and experimental results show that the proposed method is effective and feasible.In addition,the charging curves using electronic load and lead battery are basically the same,which proves that it is feasible to replace the battery with an electronic load in the experiment.Combined with the output current and voltage characteristics of the SSS compensation circuit and the LCL compensation circuit and the input impedance characteristics,the circuit topology of the charge current configurable IPT charging system based on the three-coil coupling mechanism is given,and the charging mode switching method proposed in the previous chapter is used to realize that a single inverter could charges a plurality of EBs and EBs with different charging currents can share the charging pile and the system has no reactive power input.Finally,the circuit parameter design method of the charging system is given,and the circuit simulation model of the 60V-2A and 60V-4A charging systems in parallel and the experimental prototype of the 60V-4A charging system are built.In the experiment,in constant current charging,the change rate of the 4A system of the charging current is 0.75%,and the maximum efficiency is 89.71%;in constant voltage charging,the charging voltage change rate of the 4A system is 5.1%,and the maximum efficiency is 91.86%.In the circuit model simulation,when the 2A system and the 4A system are connected in parallel to a single inverter,they can work normally at the same time;the parameters of the primary circuit and the coupling mechanism of the two systems are completely consistent,and it is verified that the EBs with different charging currents can share the charging pile.Simulation and experimental results show that the proposed method is effective and feasible.