Research On Inductively Coupled Power Transmission And Secondary Side Output Control

Inductively Coupled Power Transfer(ICPT)technology is a non-contact way to transfer power from the power supply to the load through magnetic field coupling.It is a safe,reliable,flexible and convenient power supply method.Because the coupling between the primary and secondary coils is very low during inductively coupled power transmission,the current flowing through the transmitting coil needs to be enhanced by resonance.When the excitation current is maximum,the strength of the magnetic field is also strongest,which can enhance the primary and secondary coils coupling,the difference between the compensation network and the magnetic coupling mechanism will affect the transmission characteristics of the system;in addition,the output control strategy in the field of ICPT is also a research hotspot.In the inductively coupled power transmission system,the primary and secondary sides are non-contact,Therefore,in the traditional control scheme,it is necessary to increase the wireless communication network between the primary and secondary sides.However,the delay of wireless communication limits the dynamic response of the system,and also increases the cost and complexity of the system.Therefore,the main research contents and innovations of the above problems are as follows:(1)According to the transmission characteristics of different resonant networks of ICPT system,the transmission model of ICPT system based on SS compensation and bilateral LCC compensation is established.Based on the resonance conditions,the size and phase relationship of voltage and current in the resonant network and the transmission power are analyzed with efficiency,voltage gain of resonant network,reflection impedance,input impedance and other parameters,a soft-switch parameter optimization method is adopted for bilateral LCC compensation.(2)Taking the secondary side output control as the research object,an output control strategy based on secondary side semi-controlled rectification is proposed,a power control circuit model based on secondary side active rectification is established and the working mode of the circuit is described in detail,And then analyze the relationship between the system's output power,secondary side reflection impedance,primary side input impedance,etc.and the duty cycle;a small signal model of the semi-controlled rectifier circuit is established by the state space averaging method,and the duty cycle to the output transfer function and feedback compensation parameters,and verify the correctness and feasibility of the program through simulation andexperiment;(3)Studying the transmission characteristics and optimization design problems of loosely coupled transformers,deriving the mathematical model of loosely coupled transformers,and the parameter conversion method between the leakage inductance model and the mutual inductance model,this provides a theoretical basis for the parameter measurement of loosely coupled transformers.The difference of the parameters of the three types of coils: square type,square type,and DD type;elaborate the corresponding design requirements for the ferrite core used in the ICPT system,and establish the optimal design steps of the loose coupling transformer with the maximum magnetic density,transmission power and effective transmission distance as the goal.In order to verify the validity of the theory described in the article,an experimental platform with a power of 3k W was built to verify the theory described in the article.