Fractional slot, PMSM motors with a properly designed electromagnetic circuit allow for obtaining high power density factors (more than 4 kW per 1 kg of total motor weight). The selection of the number of magnetic poles to the specific dimensions and operating conditions of the motor, as well as the number of slots for the selected number of magnetic poles is the subject of the analysis in this article. This issue is extremely important because it affects the mass of the motor, the value of shaft torque, shaft power and the value of rotor losses. The aim of the work is to select solutions with the highest values of power density factor and, at the same time, the lowest values of rotor losses. The object of the study is a fractional slot PMSM motor with an external solid rotor core with surface permanent magnets (SPM). Motor weight is approximately 10 kg, outer diameter is 200 mm and a maximum power is 50 kW at 4800 r/min. The article analyzes the selection of magnetic poles in the range from 2p = 12 to 2p = 24 and various slot-pole combinations for individual magnetic poles. The target function of the objective was achieved and the calculations results were verified on the physical model. The best solutions were 20-pole, 30-slots (highest efficiency and lowest rotor loss) and 24-pole, 27 slots (highest power density).

Contact connections in electrical machines and apparatus are important elements in the whole power supply network and a high level of reliability is expected there. Contact resistance is a fundamental criterion in the design of an electrical contact or contact system. The contact resistance should be as low as possible to minimize losses due to the current passage and the related heating of the contact connection. The value of the contact resistance depends on the material used, the value of the applied force, the type of contact, and, last but not least, the quality of the surface and chemical layers. In this paper, an initial diagnosis of the contact material is performed based on the determination of the sample’s specific resistivity by the four-wire method and the evaluation of the measurement uncertainty. The work is followed by the design of a testing device that uses crossed bars to measure the change in contact resistance as a function of the magnitude of the applied force. An analysis of the sample mounting method is performed here using FEM simulations of the current field and shows the interaction between the holder and the sample in terms of current line transfer. The proposed system is then used for experimental measurements of the material-dependent coefficient K_C for verification of existing or newly developed materials in electrical engineering, where the values of the K_C coefficient are not known. Finally, the paper also deals with the measurement of fritting voltage for individual contact pairs having surface quality corresponding to brushing.

The rapid advancement and adoption of electric vehicles (EVs) necessitate innovative solutions to address integration challenges in modern charging infrastructure. Dynamic wireless charging (DWC) is an innovative solution for powering electric vehicles (EVs) using multiple magnetic transmitters installed beneath the road and a receiver located on the underside of the EV. Dynamic charging offers a solution to the issue of range anxiety by allowing EVs to charge while in motion, thereby reducing the need for frequent stops. This manuscript reviews several pivotal areas critical to the future of EV DWC technology such as authentication techniques, blockchain applications, driver identification systems, economic aspects, and emerging communication technologies. Ensuring secure access to this charging infrastructure requires fast, lightweight authentication systems. Similarly, blockchain technology plays a critical role in enhancing the Internet of Vehicles (IoV) architecture by decentralizing and securing vehicular networks, thus improving privacy, security, and efficiency. Driver identification systems, crucial for EV safety and comfort, are analyzed. Additionally, the economic feasibility and impact of DWC are evaluated, providing essential insights into its potential effects on the EV ecosystem. The paper also emphasizes the need for quick and lightweight authentication systems to ensure secure access to DWC infrastructure and discusses how blockchain technology enhances the efficiency, security, and privacy of IoV networks. The importance of driver identification systems for comfort and safety is evaluated, and an economic study confirms the viability and potential benefits of DWC for the EV ecosystem.

The paper presents an experimental device that was created in order to obtain the real values of the forces acting in the vertical direction on the lock-off element, the so-called brake body, the 2nd design option. The lock of this design is used in the automated parking garage, designed by KOMA-Industry. s.r.o, to lock the parked vehicles on pallets in the units of the rack parking system. The forces acting in the vertical direction on the body of the fixation lock when pushing the brake pulley into the circular recess in the brake ramp are theoretically calculated for two design variants of the brake ramp used in practice, i.e. "without" and "with" a rounded (filleted) circular recess segment in the brake ramp. The experimentally determined forces acting in the vertical direction on the brake body were determined for two types of compression coil springs with a rectangular cross section of the spring wire.

The paper presents a construction design of a testing device, which was built for the purpose of checking the functional properties of the movement fixation mechanism of handling units, which is used for locking pallets with cars in place in some par...