A General Method for Estimating Coupling Coefficients in Multicoil Wireless Power Transfer Based on Harmonic Informatization

Abstract

As the core parameter of wireless power transfer (WPT), coupling coefficient ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> ) estimation can significantly improve the system characteristics. However, the relationship between <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> and electrical signals is different under different WPT topologies, so a traditional method can only be applied to one type of topology, especially due to the large number of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> in multi-coils WPT, the traditional fundamental signal is not sufficient to solve all multi-coils <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> . In order to solve the shortcomings of traditional methods in generality, a general method of estimating <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> based on harmonic-informatization is proposed in this paper. This method uses high-frequency harmonics and band-pass/stop filters to simplify the circuit, so that <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> can be simply estimated only by harmonic signal. Compared with traditional methods, this method can be applied to all topologies (including multi-coils). Also, as the circuit is simplified under high frequency-harmonics, estimating <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> requires only a few parameters for simple operations. Thus, harmonic estimation <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> offers better accuracy, speed, and cost than traditional complex methods under fundamental. This paper also experimented with <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> estimation to verify the effectiveness and accuracy of the method.