Gyrator-Gain Variable WPT Topology for MC-Unconstrained CC Output Customization Using Simplified Capacitance Tuning
Changsong Cai, Junhua Wang, Maryam Saeedifard, Pengcheng Zhang, Ruixuan Chen, Jin Zhang
Abstract
Load-independent constant current (CC) outputs are desirable in many applications of wireless power transfer (WPT). Yet the WPT gain of a conventional system is normally dependent on the magnetic components such as coils or inductors, making it difficult to customize the output for interoperability. This article presents a gain variable WPT topology for CC output customization, which only employs capacitance tuning to provide sufficient freedom in gain regulation. To break the gain limitation of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> - <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> compensation, which is the simplest with gyrator characteristics for CC output, a capacitive or inductive component is paralleled to the coil as <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SP</i> - <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> or <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> - <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">PS</i> compensation. A thorough analysis based on the Y-Δ transform indicates that the gain is restrictively variable with the parallel component. An <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> - <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CLC</i> -compensated topology without an independent inductor is further proposed to avoid those restrictions with as few additional components as possible. The inductor in the topology, coupled with the transmitter coil and integrated into the receiver coil, extends the gain variable range. A complete design process of the topology is presented to realize efficient WPT and CC output customization with a wide variable-gain range and misalignment tolerance. Analytical and simulation results confirm the effectiveness of the gyrator-gain variation by capacitance tuning. Finally, the performance of the WPT topology is evaluated by experimental results on a scaled-down prototype.