Research On Closed-Loop Wireless Power Transfer System Based On Phase Shift Control

Compared with traditional wired power supply,wireless energy transmission technology increases the flexibility of power supply,and it has become more and more widely used in fields such as smart phones.However,in the open-loop system,the uncertainty of the power transmission distance still restricts the stability of the load power supply,and it is impossible to achieve a stable working state under the condition of variable transmission distance of the system.Therefore,the closed-loop wireless power transmission system is also one of the current research hotspots.This paper studies a closed-loop wireless power transmission system based on phase-shifting control,so that when the input voltage and load are stable,when the transmission distance changes or the power coil shifts left and right,the output voltage can still be stable.This paper uses the LCC-S type topology compensation structure to study the closed-loop wireless power transmission system.Firstly,the structure of LCC-S type resonance compensation network and its transmission characteristics are analyzed,so as to obtain the relationship between its output voltage and system parameters.Combined with the analysis of the principle and mathematical model of the phase shift control strategy,the system can achieve constant voltage output.By modeling the state space of the LCC-S wireless power transmission system and analyzing the Bode plot curve of the system,it is obtained that PID control needs to be introduced to realize the regulated voltage output in the closed-loop situation.Due to the complex working conditions of the system,the transfer function is not available,and the control parameter setting is difficult.In this paper,the fuzzy PID control is used to analyze the composition of the fuzzy PID control system and the design of the program flow.It is applied to the PIC single-chip microcomputer and generates PWM wave drive phase shift control chip.The phase-shift control chip receives the signal of the single-chip microcomputer,generates four-way PWM drive waveforms,changes the phase-shift angle of the full-bridge inverter circuit,and realizes the regulated output of the closed-loop control system.Secondly,through theoretical analysis,the system is designed for hardware and software,including the parameter design of the LCC-S resonance compensation network,the selection of the PIC microcontroller and the design of the peripheral circuit,the selection of the Bluetooth module in the communication module,the selection of the phase shift control chip,and Design of peripheral circuits.Among them PIC one-chip computer carries on software programming to the control part,including A/D conversion to the voltage sampling signal,fuzzy PID control operation,PWM waveform output.Finally,a complete experimental prototype is built.The experiment shows that when the load is 10? and the transmission distance changes between 12cm-15cm,the system can achieve a stable output voltage of 48V.