Mid-ranged wireless power transfer by induction or inductive power transfer (IPT), including the strong magnetic resonance method, has been widely adopted, in numerous applications where wires are restricted. The energy flow in space, of course, is invisible to engineers. The windings are often required to be irregular shapes to accommodate the industrial designs of the products, thus, a visualisation method for energy transfer paths could greatly help the design and optimization of such systems. A time-efficient methodology, including the model, analysis and plot of the three-dimensional energy flow for IPT systems, is proposed in this paper. Algorithms of fast describing arbitrarily shaped windings are proposed and the time complexities are evaluated. A software tool, IPTVisual, is developed. It takes the inputs of key coordinates of the windings, the assignments of voltage and/or current sources, any compensation capacitors and auxiliary circuits, and the required observation points to generate the 3D models of the windings and the Poynting vectors, rendered in web browsers for the most extendable compatibility. Several example scenarios have been tested and the results match with the expected operations.

Inductive wireless power transfer systems often incorporate unconventional, irregularly shaped transmitter windings for the purposes of covering a designated area, fitting into special enclosures and enhancing the tolerance of misalignment. To design and optimise the winding structures, the inductive parameters must be extracted and linked to the design objectives. Conventionally, these parameters can be extracted using three-dimensional finite element analysis, which often requires subjective manual tweaks and prolonged trial and error procedures. The efficacy is therefore greatly dependent on the experience of the designer. In this paper, a case study for modelling and optimising the spatial coverage by scuplturing the winding shape is demonstrated via a Christmas tree model, utilising the parametric formation equations and line-integral based numerical solvers. A cone-shaped winding with variable interturn pitches was used as the transmitter and a receiver winding was designed to be fit into a bubble that can be hung on the tree. A two-stage optimisation method with simplified degree-of-freedom parameters and brutal force search was used to find the optimal design candidate. Heatmaps of receiver output voltages were generated in a time-efficient way, intuitively helping the designers to make adjustments for the winding structures. A practical prototype was built to verify the open loop voltage distribution on the receiving winding at various positions and another demonstration was made to show the continuum of power coverage around the Christmas tree.

The first generation of wireless power transfer (WPT) standard Qi, launched in 2010, contains a wide range of transmitter and receiver designs with the aim of maximizing compatibility to attract many manufacturers to share the same standard. Such compatibility feature (i.e., interoperability) has not only attracted over 400 company members in the Wireless Power Consortium (WPC), but also facilitated a fast-growing wireless power market for a decade. The WPC is now expanding the scope of WPT applications to mid-power and high-power applications up to several kilowatts while the Society for Automobile Engineers also set the SAE standard for wireless charging of electric vehicles (EVs) up to tens of kilowatts. Without compromising compatibility, the authors share in this paper their views on the need for a paradigm shift from compatibility to optimal performance in terms of maximum energy efficiency for the entire charging process and minimum charging time. This paradigm change is imminent and important in view of the increasing power of WPT applications. Several enabling technologies essential to the paradigm shift will be addressed.