Efficient Methodology of the Coil Design for a Dynamic Wireless Charger

Abstract

from the "Proyectos de I+D+i -RTI Tipo A" program."ABSTRACT Dynamic charging is a promising technology that will increase the use of electric vehicles with reduced battery requirements. Designing this type of system is more complex than for a static charger, and leads to a significantly higher demand of computational resources. First, the complex geometries of the coils do not allow analytical equations to be used, and FE tools must therefore be used instead. However, the Litz wire conductor used in these coils will pose a computational problem if it is not well modelled. The second difficulty is that these systems should be analysed with more potential relative positions between the coils, as misalignment is intrinsic in a dynamic charger. These two complications mean that the design process can greatly benefit from techniques that reduce the time taken to derive the coil parameters. This paper shows the feasibility of using an equivalent layer to model the Litz wire in a dynamic charging application, which significantly reduces the computational time of each iteration up to 20 times. As a consequence, the complete design process is faster and accurate. For this demonstration, we illustrate the design for a dynamic charger of a remote control car.

Optimized Design of a Wireless Charger Prototype for an e-Scooter

“…For the managed power, the effects of the non-idealities of the components are more relevant, so the parasitic resistances of the transistors and diodes notably degrade the system efficiency. The same effects were perceived in the low-power application described in [30].…”

Design of a Misalignment-Tolerant Inductor–Capacitor–Capacitor-Compensated Wireless Charger for Roadway-Powered Electric Vehicles

“…Polarized geometries, on the other hand, namely the double-D (DD), double-D quadrature (DDQ) and bipolar coils, utilize the parallel components of the magnetic field for power transfer, which provides higher coupling across large separation distances between the primary and secondary sides [25,32,33]. However, the authors in [34][35][36] report significantly low coupling values during misalignments, and hence poor misalignment tolerance, between primary-and secondary-side DD coils due to the inherent null coupling point [37]. This motivates the utilization of multi-coil structures such as the DDQ and bipolar coils to leverage on the individual advantages of each coil geometry while offering additional design degrees of freedom to overcome their disadvantages [38,39].…”

“…The authors in [35] propose an algorithm for designing optimal coils that maximize the AC power transfer efficiency of the IL in DWC systems at 30% and 50% lateral misalignments using series-compensated and DD primary and secondary coils. Nonetheless, acknowledging the shortcomings of series compensation in maintaining resonance of the IL during misalignments [45], hybrid compensation topologies, including inductorcapacitor-capacitor (LCC) and inductor-capacitor-inductor (LCL) compensation, are utilized in [46][47][48][49][50][51] and offer additional degrees of freedom to design load-independent inductive links.…”

“…Their proposed LCC-series compensation offers a constant voltage (CV) output to the EV battery at lateral misalignments up to 75 mm from the perfect alignment position, while maintaining a constant operating frequency, with a decreasing DC efficiency as misalignment increases. It is noted that the amount of misalignment is typically measured as the net displacement from the central axis of the coil along the length of the EV, as in [52], or as a percentage from the coil dimension to the right or left of its axis, as in [35]. LCC-series compensation is also utilized for improving the misalignment tolerance of DWC systems in [53][54][55][56].…”

Electromagnetic Characterization of Hyperconducting Aluminum Litz Wires at Cryogenic Temperatures

“…A Litz wire, comprising multiple insulated metal strands twisted or braided together, effectively mitigates highfrequency losses attributed to skin and proximity effects. As a result, Litz wires have gained traction in various power electronic applications, including power converters [18][19], wireless power transfer systems [20][21], electric motors, and generators [22][23]. Given the high-frequency environment in the AC windings of CEMs and electric aircraft drives, Al Litz wires have the potential to address the persistent challenge of AC losses encountered with HTS tapes, while exhibiting relatively lower DC loss compared to Cu Litz wires at cryo-temperatures.…”