| Inductive power transfer(IPT),a non-contact energy transfer method based on the principle of electromagnetic induction,is characterized by the safety,reliability,flexibility and has been widely concerned and studied by scholars in related fields.At present,the research on IPT technology has obtained rich achievement,and related products have been promoted and applied in many fields,showing its broad application prospects.Bidirectional inductive power transfer(BD-IPT)technology has special value in many fields.For example,providing power feedback channel for electric driving system and electric vehicle braking system to improve system efficiency,transferring the load electric energy to the power grid in the reverse direction,and participating in the regulation and control of peak load shifting of the grid;In addition,the bidirectional wireless flow of electric energy is also critical to radio energy networking.With the development of research,the BD-IPT system with high efficiency and simple control is the focus of future research.The existing literatures pay more attention to the realization of bidirectional transmission function,and considers less about the stability and efficiency of the system.In BD-IPT system,the converters on both sides work in a controllable state,and the synchronization of their control signals is significant to the stable power transfer.In view of the shortcomings of the existing synchronization methods,such as poor robustness and high cost,the synchronization method of tracking the output DC current extremum is adopted in this paper.For the low efficiency of single phase-shifting control method in low power transmission,the double-sided phase-shifting control strategy is adopted to keep high transmission efficiency in a wide range of output power.The main work of this paper is as follows:Firstly,this paper introduces the research background and the structure of BD-IPT system,and expounds the research status in the fields of BD-IPT system mathematical model building,efficiency and power control strategy,converter control signal synchronization method,optimization design of magnetic circuit mechanism,transmission characteristics analysis,and summarizes the purpose and significance of this paper.Next,the transmission power characteristics and efficiency characteristics of BDIPT system are analyzed.When the converters on both sides are controllable,the transmission efficiency is improved by making the system work in the optimal output AC voltage ratio state.At the same time,aiming at the problem of indefinite delay in the wireless communication synchronization method,a synchronization method is designed to track the maximum value of output DC current,which realizes the stable power transmission and avoids the problem of power oscillation due to the periodic change of output AC voltage phase angle difference.Then,the advantages and disadvantages of the existing control methods and the reasons for losses are analyzed.In order to further improve the efficiency of the system in a wide power range,a bilateral phase-shifting control strategy is proposed.The control strategy not only makes full use of the existing devices of the system,but also ensures the stable and reliable operation of the system.Finally,the theoretical analysis is verified by software simulation and experiment.The results show that the synchronization method designed in this paper can effectively achieve the precise synchronization of the converter control signal,and the bilateral phase-shift control strategy can achieve high-efficiency power transmission in a wide range of transmission power.50 figures,5 tables and 103 references are included in this paper. |
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