Design Of Wireless Charging Foreign Body Detection System Based On Induced Voltage

Wireless power transfer technology has the characteristics of convenient,flexible and reliable power supply,and it has improved the defects of traditional wired transmission lines such as aging and site limitation.Magnetically coupled resonant wireless power transfer technology has become a research focus of Wireless power transfer technology due to its balanced performance in transmission distance,transmission power and transmission efficiency.Magnetically coupled resonant wireless power transfer technology still needs to overcome some important problems in practical applications.The metal foreign body intruding into the system will reduce the transmission efficiency of the system due to eddy current loss,and affect the safety and reliability of the system operation.In order to ensure the transmission efficiency of the system and improve the security and reliability of the system,this paper has carried out a series of exploration and demonstration on metal foreign body detection of magnetically coupled resonant wireless power transfer system and load identification of array system.The main results are as follows:Firstly,aiming at the hidden safety problems caused by metal foreign body invasion in magnetically coupled resonant wireless power transfer system,this paper proposes a three-stage locating and detecting system for metal foreign body.In order to clarify the influence mechanism of metal foreign body on the magnetic field environment of the system and to obtain a reliable detection method,this paper compares and analyzes the influence of metal foreign body on the magnetic field environment of the system from three aspects: material,size and position of metal foreign body;Based on the influence mechanism of metal foreign body on the magnetic field environment of the system,this paper proposes a three-stage locating detection system for metal foreign body applied to the magnetically coupled resonant wireless power transfer system,which will not affect the transmission power and efficiency of the system;Through the joint simulation of the magnetic coupling actuator in "Maxwell" and the external circuit in "Simplorer",the system detection threshold voltage of 1.4V was determined;Finally,an experimental prototype is built to verify the effectiveness of the magnetically coupled resonant wireless power transfer system.Secondly,in view of the security problems caused by the no-load operation of the array radio energy transmission system,this paper proposes a method of load identification and charging area selection by switching between polar magnetic field and non-polar magnetic field at the transmitting terminal.The detection method does not need any additional structure,and through the special transmitting terminal structure of the array radio energy transmission system,the magnetic field at the transmitting terminal can be switched;In order to achieve a good triggering effect of the system,the structure of the trigger coil attached to the receiving coil is optimized for the detection dead zone in the complex magnetic field environment at the transmitting terminal of the array system,and finally the structure of the trigger coil with a cross length arrangement of 30° is proposed;Finally,the effectiveness of the method is verified by simulation.