Beyond Inductive and Capacitive: A Review of Hybrid Wireless Power Transfer Systems

Wireless power transfer enables the powering of a load without the need for physical cables, significantly enhancing user experience. In the near-field region, the literature distinguishes between inductive- and capacitive-coupled systems, where power is transferred through either magnetic or electric fields. Inductively coupled systems, in particular, are considered a mature technology. However, due to limitations in single-coupling systems, recent research has started to explore combining these mechanisms into a single coupler, often referred to as hybrid wireless power transfer. As a result, these hybrid systems not only maximize the use of their components but also tend to outperform conventional wireless power transfer systems in terms of misalignment tolerance and power density. This work provides an overview of the main operating principles, analysis methods, bottlenecks (with potential solutions based on existing hybrid or single-coupled systems), and future research directions. Special emphasis is placed on existing systems, which are often developed ad hoc to address challenges faced by conventional single-coupling systems. Additionally, some existing setups already apply hybrid wireless power transfer to specific application fields, which are also covered in this work.