Investigation of relationship between coupling coefficient and power factor for non-contact chargers

In the present paper, the relationship between the coupling coefficient and the power factor for non-contact chargers is investigated through calculations. Although the design for improving the power factor was strictly performed, the power factor could not be always maintained at 1, because the non-linearity of the internal resistances of the diodes led to the generation of the current harmonic components in the sending and receiving circuits. Thus, the author attempted to decrease the coupling coefficient between the sending and receiving coils as much as possible without decreasing the power transfer efficiency. The coil constants such as the self- and the mutual inductances and the AC resistances were calculated by finite element analysis. After finite element analysis, the equations derived from the equivalent circuit for the non-contact charger were calculated by the Runge-Kutta method. Moreover, the validity of the calculation results was validated through comparison with experimental results.