A High Misalignment-Tolerant Trapezoids-Circling-Square Pad for Wireless Power Transfer Systems

In the process of wireless power transfer (WPT), coil misalignment significantly affects output stability. This paper presents an innovative magnetic structure, the trapezoids-circling-square pad (TCSP), designed to mitigate the substantial performance degradation in WPT systems caused by coil displacement. The TCSP consists of an internal rectangular coil and an external coil. The external coil, arranged in a circle that encloses the internal coil, is composed of four identical trapezoidal sub-coils connected in series. The external and inner coils achieve decoupling due to their specific winding and spatial design. Both receiving coils are individually compensated and then connected in parallel post-rectification. This design exhibits strong fault tolerance against coil misalignment, maintaining the equivalent mutual inductance between the primary and secondary coils within a narrow range of fluctuations. Furthermore, by leveraging the aforementioned constant equivalent mutual inductance and employing the LCC-LCC compensation topology, a stable current output can be achieved, thereby enhancing system output stability. Experimental results reveal that within an offset distance of 66.67% of the TCSP’s maximum dimension, the proposed magnetic couplers demonstrate robust tolerance to two-dimensional displacement, with fluctuations in output current of only 4.05% and a peak efficiency of 90.06%.