**5. Implementation on a Concrete Demonstrator**

Within the E|Profil project funded by the BMWi and DLR, a demonstrator was set up at FAU. The design is specified in accordance with WPT3 SAE J2954 [27]:


• Dimension: ~300 mm × 300 mm (based on SAE2954 (WPT3 Z1)) [27] • Dimension: ~300 mm × 300 mm (based on SAE2954 (WPT3 Z1)) [27]

up at FAU. The design is specified in accordance with WPT3 SAE J2954 [27]:

eddy current losses low and to prevent electrical breakdown [24–26].

**5. Implementation on a Concrete Demonstrator**

*Energies* **2022**, *15*, x 8 of 13

• Input: 11.1 kVA and 400 V • Input: 11.1 kVA and 400 V

• WPT Power class, 11 kW • Coil-to-Coil efficiency > 96%

• Stranded HF litz wire • Stranded HF litz wire

The selection and implementation of the processes for the project demonstrator will be described in the following sections. The selection and implementation of the processes for the project demonstrator will be described in the following sections.

polyamide, polyester, polyethylene or polyimide. Despite the large number of individual conductors, this leads to a high degree of cohesion of the strand and to a high mechanical stability during the laying of the coil. The secondary insulation ensures the protection of the electrical components against mechanical and chemical environmental impact and the dissipation of generated heat. A dielectric potting material should be selected to keep

Within the E|Profil project funded by the BMWi and DLR, a demonstrator was set

#### *5.1. Laying of the Litz Wire 5.1. Laying of the Litz Wire*

After the controlled uncoiling of the stranded wire from the supply reel, the stranded wire is laid with a coiling tool. For this purpose, a specific guide and wire tension control for stranded wire have been integrated into a custom universal 15-axis winding machine. The wire is guided to the deposit point and deposited in a rotating spool carrier with guide grooves which remains in the subsequent spool module (see also Figure 5 (left)). After the controlled uncoiling of the stranded wire from the supply reel, the stranded wire is laid with a coiling tool. For this purpose, a specific guide and wire tension control for stranded wire have been integrated into a custom universal 15-axis winding machine. The wire is guided to the deposit point and deposited in a rotating spool carrier with guide grooves which remains in the subsequent spool module (see also Figure 5 (left)).

**Figure 5.** Manufacturing cell for flat coil winding (**left**), ultrasonic welding system and contacted litz wires (**right**). **Figure 5.** Manufacturing cell for flat coil winding (**left**), ultrasonic welding system and contacted litz wires (**right**).

#### *5.2. Contacting 5.2. Contacting*

Within the scope of the production of the demonstrator, various contacting solutions for contacting the high frequency litz wire are being evaluated. These include the already mentioned technologies of hot and ultrasonic crimping, but also processes that enable a contacting on contact terminals. The primary insulation used complicates terminal contacting in particular. Nevertheless, it has been shown that torsional ultrasonic welding can also be used to weld primary-insulated litz wires directly onto contact terminals. In a twostage process, the litz wire is compacted, stripped and welded onto the terminal. However, necessary gap dimensions between the tools as well as burning residues require further optimization of the welding process. Furthermore, the ultrasonic crimping process shows to be an energy-efficient alternative contacting technology for tubular cable lugs. However, there is also a demand for further optimization of this process in order to ensure that the technology is suitable for series production. The hot crimping process has proven to be an extremely robust and well-suited process. The achievable contacting quality is Within the scope of the production of the demonstrator, various contacting solutions for contacting the high frequency litz wire are being evaluated. These include the already mentioned technologies of hot and ultrasonic crimping, but also processes that enable a contacting on contact terminals. The primary insulation used complicates terminal contacting in particular. Nevertheless, it has been shown that torsional ultrasonic welding can also be used to weld primary-insulated litz wires directly onto contact terminals. In a two-stage process, the litz wire is compacted, stripped and welded onto the terminal. However, necessary gap dimensions between the tools as well as burning residues require further optimization of the welding process. Furthermore, the ultrasonic crimping process shows to be an energy-efficient alternative contacting technology for tubular cable lugs. However, there is also a demand for further optimization of this process in order to ensure that the technology is suitable for series production. The hot crimping process has proven to be an extremely robust and well-suited process. The achievable contacting quality is subject to only minor fluctuations. By slightly adjusting the process parameters, it is also possible to join taped and PAI primarily insulated high-frequency litz wires to tubular cable lugs. Therefore, the hot crimping process is used as a reference contacting process in this research project. However, the extremely promising torsional ultrasonic crimping and welding process will be further optimized for future applications. Figure 5 (right) shows, in addition to exemplary test samples, the ultrasonic welding system used and various contacts produced.
