With growing interest in green technologies and sustainable transport, hybrid and pure electric powertrains are attracting a lot of attention. According to demanded metrics, such as lightweight and high-power density motors, these offer clear motivation to develop advanced thermal management methods and integrate them with conventional cooling approaches. The oil spray cooling method is one of the latest cooling methodologies integrated with the conventional cooling approaches. Therefore, this article provides a comprehensive study on the oil spray cooling approach for electrical motors utilized in electric vehicle (EV) traction application drives. The objective is to provide the reader with a picture of the state of the art regarding the opportunities, challenges, and offered solutions for the cooling requirements in EV motors. In addition, this article presents the guidelines for selecting the appropriate spray nozzles and coolants as well as estimating their performance, spray characteristics, and heat transfer coefficient (HTC) during the design period. Besides, various closed-loop systems of spray cooling approach, including refrigerants as a coolant, low viscosity liquid coolant with high boiling temperature, and high viscosity lubricant oil as a coolant, are discussed with the pros and cons of each system being compared. Moreover, real-life examples of this method, applied in the latest automotive traction motor prototypes, have been described and evaluated. Finally, the performance of different schemes is addressed.

The additive manufacturing approach is considered a new manufacturing technology method and is evolving dynamically in recent years. It is advancing and achieving as the key enabling technology in a wide range of applications, from medical sciences to the aerospace and automotive industries. This novel approach opens a new path to overcome the conventional manufacturing problems and challenges by providing more design freedom, new ranges of materials, lightweight and complex geometries. According to demands metrics such as lightweight and high power density motors. This offers clear motivation to develop the advanced thermal management method with new materials and a novel additive manufacturing (AM) approach. The paper aims to provide a comprehensive review of all the attempts in various electrical machines' thermal management methods using AM method. It considers the opportunities and challenges that designers are facing while implementing these approaches. Finally, the authors make some comments/forecasts on how the AM could improve the performance and manufacturability of the future thermal management system of electrical machines.

The hairpin winding configuration has been attracting attention as a solution to increase the power density of electric vehicle motors by enhancing the slot-filling factor. However, this winding configuration brings high AC losses during high-speed operation and we require new approaches to tackle this challenge. This paper considers reducing AC losses by proposing two main methods: correct transposition of conductors in parallel paths, and enhancing the number of conductor layers in a slot. First, the proper connection of conductors in parallel paths is considered, and the essential rules for this purpose are described. Next, the paper uses a numerical approach to deal with the effect of incorrect conductor transposition in winding paths on generating additional AC losses due to circulating currents. Finally, the impact of the number of conductor layers in the mitigation of AC losses is also discussed in detail. According to the results, by increasing the number of layers, ohmic losses in the layer near the slot opening dramatically decrease. For instance, ohmic losses in the layer near the slot opening of the eight-layer setup were 82% less than the two-layer layout.

This paper presents the analytical calculation of the heat transfer coefficient of a complex housing shape of a Totally Enclosed Fan-Cooled (TEFC) industrial machine when it works below 20% of its nominal speed or close to stall. Therefore, passive cooling is dominant, and most of the heat is extracted by the combination of natural convection and radiation phenomena. Under these conditions, the area-based composite approach was used for the development of the analytical calculation method. A test rig using a TEFC Synchronous Reluctance Motor (SynRM) was constructed, and the collected experimental data was used to validate the proposed analytical method successfully.

The present paper deals with the concept of a cost-effective power-assistant wheelchair. An analysis of the market situation and recent technical achievements is done at the beginning. On its basis, a set of solutions suitable for the development of such wheelchairs has been composed. It is shown that the key features of the considered concept are: segmented electrical motor and drive, sectioned battery pack, modular charger and an ANN matrix that provides easy and intuitive interfacing of sensor networks, pseudo-bionic feedbacks and the decision-making unit. Within the scope of the paper, a 3D model has been developed and 3D modelling has been conducted. As a result, certain drawbacks in the design and placement of elements have been found and a modification of the concept has been proposed