Research On Constant Current/Constant Voltage Output Regulation And Efficiency Improvement Method For Double Half-bridge IPT System Based On Variable Inductors

To solve the problems caused by the conventional wired power transfer technology,such as cumbersome plugging and unplugging,safety hazards,etc.,in the recent years,the wireless power transfer(WPT)technologies has been significantly researched and developed by scientists due to its convenience,safety and other unique advantages.Among them,inductive power transfer(IPT),as the one category of the WPT technologies,has become the main development trend since its relatively long transmission distance,low electromagnetic radiation,high transmission power and efficiency.However,to further promote the application of this technology,the two key requirements should be satisfied for an IPT system: 1)excellent output current/voltage regulation capability;2)high transfer efficiency.In view of that,this project takes the output controllability and high efficiency into account,focuses on the design of controllable reactive components,system power transfer characteristics,efficiency improvement and other issues,and then,a high-efficiency IPT system for constant current(CC)/ constant voltage(CV)output regulation has been proposed based on the variable inductors and a double half-bridge(DHB)inverter.Finally,a laboratory prototype is built to verify the theoretical analysis.First,the working principle and design scheme of the variable inductor are introduced in detail.Based on the magnetic circuit analysis theory,a magnetic circuit model is built,and the relationship between the key design parameters(such as the number of main winding turns,auxiliary winding turns)and the variation range of the inductance value is derived.Finally,a detailed design scheme of a magnetically controlled variable inductor is proposed based on the inductance variation range,which provides a feasibility basis and theoretical foundation for the theoretical analysis and design of the IPT system.Then,with the objective of the high-efficiency constant output control of the IPT system,the topology and control strategy of the IPT system based on the variable inductors and a double half-bridge(DHB)inverter are studied and proposed.Based on the mathematical analysis of the circuit,the relationship between the two variable inductors is determined by considering the minimum conduction loss of the switching devices,and the expression of the circuit parameters and the output gain are provided.Furthermore,the feasibility of the output control method is verified by the simulated results.Moreover,a power losses model is established to analyze the power loss in each part of the system,and then,the calculated equation is provided respectively.The results show that the full-range soft switching operation of the switching devices can be achieved by using the proposed control method while satisfying the constant output control of the system,and the conduction loss is reduced to one quarter.Finally,with the topology circuit and the design parameters of each-part components,an experimental prototype is built to verify the effectiveness and feasibility of the proposed control method.The open-loop verification and closed-loop control strategies are designed respectively,and the output control,soft-switching realization and efficiency improvement of the proposed control method are recorded and verified compared with the conventional phaseshift control.As results,close agreement is obtained between the theoretical analysis and experimental results.The maximum efficiency can reach 92.4%,which is 3.65% higher than that of traditional phase-shift(PS)control.