**2. Components and Types of Wireless Power Transfer**

The idea of wireless power transfer has existed since the late 19th century [3]. Currently, a variety of different systems exists with transmitting powers from 10<sup>0</sup> W (e.g., mobile phones) up to 10<sup>5</sup> W to supply power into electrical trains.

Particularly in the field of medical and consumer products, WPT systems are proven and widely used. Aboutfifty years ago, the first WPT artificial implanted heart have been published [4]. At the end of the 1970s, WPT charged electric toothbrushes [5] kicked off the success story of wireless power transfer in the consumer industry. The integration in the industrial production was triggered in the 1990s by automated guided vehicles (AGV), of

**Citation:** Kuehl, A.; Kneidl, M.; Seefried, J.; Masuch, M.; Weigelt, M.; Franke, J. Production Concepts for Inductive Power Transfer Systems for Vehicles. *Energies* **2022**, *15*, 7911. https://doi.org/10.3390/en15217911

Academic Editor: Adel El-Shahat

Received: 31 August 2022 Accepted: 14 October 2022 Published: 25 October 2022

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

which wireless charging was an improvement because of its greater robustness and lower maintenance [6].

WPT systems for electric vehicles (EV) have been a logical extension of this. They have already existed in research projects since the 1970s [7] and have spurred new interest as recent improvements in material and power electronics have arisen. In a direct comparison, automotive applications have requirements that are more stringent in the points of air gaps, power level and power density as well as safety (several nations have defined safety limits, values and zones for the electromagnetic field, e.g.,), compared to AGV applications [6]. In 2021, Momentum Dynamics issued a declaration of CE conformity for its up to 300 kW wireless charging solutions [8].
