ANALYSIS OF THE EFFICIENCY OF ELECTRIC POWER TRANSMISSION IN THE SYSTEM OF WIRELESS CHARGING OF THE ELECTRIC VEHICLE'S BATTERY

Abstract

Theoretical researches of efficiency of electric energy transfer in the wireless charger of inductive type with serial resonance in circles of transmitting and receiving coils are carried out. It is shown that this efficiency depends on the parameter (the product of the magnetic coupling coefficient and the Q- factor of the coils) and the ratio of the active resistances of the battery and the coil. It is shown that there is an optimal value of this ratio, at which the efficiency of the device is maximum (when ) and its value increases monotonically with increasing parameter . Moreover, to achieve an efficiency greater than 0.8, it is necessary to have a system of coils with a value of 10. The graphical dependences that determine the value of this efficiency as a function of these two parameters and set the allowable interval for changing the resistance ratio in terms of high energy efficiency. Numerical calculation of the high-frequency magnetic field (with an operating frequency of 100 kHz) generated by the coils was performed, in two cases - in the absence of shielding and in the presence of aluminum electromagnetic screens and showed high efficiency of such screens. The peculiarity of the calculation is that to determine the values of complex currents in both coils, which depend on the mode of operation of the whole device, use their preliminary calculation based on the created Simulink-model of the device. References 14, figures 5, table 2.