In the vehicle electrification sector, the precise and reliable control of e-motors is of the utmost importance for ensuring the efficient and safe operation of the whole electric vehicle drivetrain. Specifically, the assessment of the absolute rotor position of the permanent magnet-based synchronous motors is necessary for precise e-motor control, which is strongly determined by the precision of the sensing device used for the absolute rotor position assessment. Magnetic rotational position sensing devices/encoders are predominantly used in the automotive sector. The accuracy of a magnetic-based rotational position sensing device can be affected by defects/errors which may occur during its manufacturing and/or assembly process. These defects may in turn affect the accuracy of the e-motor’s control and operation. The primary objective of this study was to numerically and experimentally design and investigate the accuracy of a magnetic-based off-axis rotational position sensing device intended for the control of a new permanent magnet e-motor, which was developed for a two-wheeler electric vehicle drivetrain. First, a 3D parametric numerical model of a magnetic rotational position sensing device mounted on the motor shaft was built by virtue of the finite element method (FEM). Based on numerical simulations, the appropriate dimensions of the magnetic ring were determined and the possible errors which may have occurred during its manufacturing process have been numerically imposed and analyzed. Second, the rotor position sensing device was prototyped based on the recommendations obtained with the 3D FEM model. Finally, the accuracy of the designed rotational position device was then experimentally assessed by comparing it to a standardized end-of-shaft rotational position encoder. To evaluate the influence of the possible errors on the e-motor rotor position measurement, the output characteristics of the motor torque as a function of its rotational speed of a real permanent magnet e-motor were experimentally assessed using two different rotational position devices. Based on the numerical end experimental results, we identified the manufacturing errors of the magnetic ring and analyzed their influence on the resulting output characteristics of the e-motor. The results revealed that the magnetic ring eccentricity and its magnetization process could affect the accuracy of the e-motor’s output torque characteristics.

This work provides an overview of the key steps involved in designing an electric powertrain for an L7 category vehicle intended for urban and suburban environments. It focuses on mission-specific rightsizing and physical integration into small vehicles. Synthetic driving cycles of Helsinki, Finland, and Regensburg, Germany, created via activity-based transport modeling and dynamic vehicle simulation reveal that urban use cases do not require high power and torque. This allows for smaller battery capacities and electric motor ratings, leading to cost savings in mass production. Moreover, this paper introduces two powertrain variants: a low voltage option and an extensive high voltage option with both conventional conductive and wireless charging systems. The high voltage variant was selected for implementation and for that, the first measurement results are presented. Both low voltage and higher voltage options are technically feasible, but if wireless charging is preferred, the higher voltage configuration is more suitable from a system design perspective.

Shaded-pole induction motors are the most frequently used single-phase electric motors in low power applications. Their main advantages are reliability, robustness, low level of noise and vibration, relatively simple manufacturing technology and cost effectiveness. These motors are the driving units of choice in the applications where the variable speed and high starting torque are not of utmost importance, in spite of the fact that they are characterized by inferior efficiency, power factor and starting torque compared to their single-phase counterparts. They are equipped with auxiliary massive copper coils at the stator side, which makes them self-starting, and strongly influence the motor characteristics. This study deals with the numerical modeling and analysis of a shaded-pole induction motor with a C-shaped stator frame. The analysis was performed using 2D finite element-based transient magnetic numerical modeling. The primary objective was to investigate the influence of the number and size of the auxiliary shaded coils on the output torque speed characteristic. We explored the possibility of reducing the amount of material used while preserving the crucial/nominal properties of the motor. Our results have important implications in manufacturing simplification, which may be important for the eco-design of small motors and actuators, including their recycling and/or reuse process.

The aim of paper is to present the workflow of battery sizing for electric L7e-CU type vehicle. The intention is to use it as last-mile delivery multi-purpose vehicle. Based on legislation limits and pursuing the real-world driving cycle, major vehicle characteristics as total vehicle mass including payload and wheel size are determined. Vehicle total energy consumption is calculated knowing vehicle power in time. Accordingly, to selected gearbox ratio the electric motor nominal power-speed curve is defined as well as the nominal torque-speed curve. Applying vehicle acceleration dynamics involving limits considering resistive forces, acting on the vehicle, e.g. slope, friction, air drag, and total inertia, referred to the electric motor through the gearbox the electric motor over-load-ability characteristics are calculated. Next, the motor design is defined and optimized. Defining required vehicle range at given driving cycle and knowing the vehicle and all powertrain characteristics allows to properly define the battery characteristics e.g. nominal voltage, battery cell type, current capacity, energy storage, dimensions and its mass.

Shaded-pole induction motors belong to the group of most used small electric motors in low-power applications ranging from a fraction of a watt up to few 100 W. They are most often found in fan drivers, small pumps, beverage dispensers, washing machines and many household appliances. They are frequently used due to their advanced manufacturing technology, cost effectiveness, robustness, reliability and low noise and vibration levels, despite their poor efficiency, which is usually below 40%. The shaded-pole motors are often designed as two -pole machines. Depending on the construction of the stator package of the two-pole version, they can be divided into symmetrically and asymmetrically designed motors. The objective of the paper is to build a 2D finite-element-based numerical model of a C-shape shaded-pole induction machine (i.e., asymmetrical type) using the transient magnetic analysis. The impact of the number of the auxiliary winding turns and the rotor skewing angle on the resulting torque-speed curve and the torque pulsations is investigated. Finally, the possibility is considered to reduce the amount of the used material to simplify the manufacturing, which may be important for the recycling and/or reuse process.

In this article the review of the existing manufacturing technologies of the soft magnetic materials have been performed. The existing technological protocols for production of the electrically insulated powders and their further treatment towards manufacturing of the soft magnetic materials are provided. The influences of different technological processes on the mechanical, electrical and magnetic properties of the resulting soft magnetic materials have been reviewed and described. Finally, the usage and implementation of the soft magnetic composites in the field of electric motor design have been discussed.

Disposable sterile needles are essential highly consumed medical tools. Medical needles are usually manufactured according to standardized protocols, which currently do not provide the specified minimum tolerance value of the penetration force which strongly depends on needle dimensions, needle cutting edge angle, and the type of the tissue surface to be penetrated. In the present study, experimental measurements were performed according to the ISO 7864 standard to investigate the needle-surface penetration effect via the experimental assessment of the influence of the needle dimensions, cutting edge angle, and three different types of biomedical textiles/artificial tissues (i.e. polyurethane (PU), polypropylene (PP), and artificial leather (AL)) on the penetration force. The results indicate that the smaller the needle's cutting-edge angle, the smaller the penetration force across the target tissue surface. An exponential decaying relationship has been found between the penetration force and the needle diameter/gauge. The results also show that PP provides similar results to other materials that are already included in ISO 7864, and it has a good potential to be accepted as a standardized biomedical textile.

The main heat transfer mechanism in the end-winding region of electrical machines is convection. In order to increase the air motion, the rotor is equipped with a series of blades. Their geometry is reflected in the fanning factor, i.e., the ratio between the rotor peripheral speed and air velocity. An accurate calculation procedure for the fanning factor has not yet been given. Knowing its value is crucial for the determination of air velocity and heat transfer coefficient (HTC), as the latter describes the end-winding heat removal capability. In this study, the convective heat transfer phenomena between the end winding and air inside the end-winding region were analyzed, with the heat generated only in the end winding, mimicked with a custom designed coil, and air moved by the blades. The analysis was performed by experimental testing and computational fluid dynamics (CFD) modeling. Measurements data were used to build a reliable CFD model. Further on, CFD results were used to derive a generalized analytical equation for calculation of the end-winding HTC, related to blade geometry and rotor rotational speed. The developed analytical model significantly improves the quality of real-time lumped circuit thermal modeling of electrical machines and, thus, enriches this field of science.

In this article, the temperature and the cooling medium (i.e. air) distribution inside a three-phase induction motor has been studied based on numerical modeling. The numerical computational fluid dynamics and the thermal analysis within the induction motor has been used. Two cooling possibilities of the three-phase induction motor have been analyzed and compared.

Laser welding is an innovative method that is frequently used and required by different disciplines and represents a technique of choice in a wide range of applications due to important advantages such as precision, speed, and flexibility. However, the welding method must be used properly otherwise it may deteriorate the mechanical properties of the welded metal and its environment. Therefore, the laser parameters should be precisely determined and carefully applied to the sample. The primary objective of this study was to investigate and propose optimal welding parameters that should be adjusted during the neodymium-doped yttrium aluminum garnet (Nd: YAG)-pulsed laser welding of austenitic stainless steel 316L in an air welding environment by using Argon shielding gas and in wet welding settings in serum medium. The investigation of the welding process in serum medium was conducted in order to propose the most suitable welding parameters being important for future possible medical applications of laser welding in in-vivo settings and thus to investigate the possibilities of the welding process inside the human body. In order to evaluate the quality of welding in air and of wet welding (in serum), a detailed parameter study has been conducted by variation of the laser energy, the welding speed and the focal position. The relationship between the depth of penetration and specific point energy (SPE) was also evaluated. The microstructure of the welded metal was examined by an optical microscope and scanning electron microscope (SEM). Based on the microscopy results, it was found that the largest depth of penetration (1380 µm) was achieved with 19 J laser energy in air medium, while the depth reached the largest value (1240 µm) in serum medium at 28 J laser energy. The increasing energy level showed opposite behavior for air and serum. The results of our study imply that when welding of 316L stainless steel is implemented properly in the body fluid, it would be a promising start for future in-vivo studies.

Ti6Al4V titanium alloys are widely used in a variety of scientific and industrial fields. Laser beam welding is one of the most effective techniques for the joining of titanium plates. The main objective of this study was to investigate the influence of the most important laser parameters on welding performance of titanium alloy in two different physical environments such as air and water (i.e., serum) media. Specifically, the laser beam welding of 2 mm thick Ti6Al4V samples was applied using an Nd:YAG laser in open-air welding using argon as a shielding gas, and in wet welding using a serum environment. The deepest penetration was achieved at −3 mm focal position with 11 J of laser energy in both investigated media (i.e., air and serum). The maximum hardness (1130 HV) was achieved for the focal position of −4 mm in serum medium while it was 795 HV for a focal position of −5 mm in air medium. The minimum (1200 μm and 800 μm) and maximum (1960 μm and 1900 μm) weld widths were observed for air and serum medium, respectively. After the welding process, martensite, massif martensite, and transformed martensite were observed in the microstructure of Ti6Al4V. To the best of our knowledge, the underwater wet welding of titanium alloy was carried out and reported for the first time in this study.

In this paper, the influence of the end winding leakage inductance on the three-phase induction motor characteristics has been investigated. The most common analytical equations used for the end winding leakage inductance calculations are analyzed, compared and implemented into the finite element method based models of the induction machine. The main differences between the end winding leakage inductance calculation approaches have been identified via comparison of the output motor characteristics obtained from the 2D numerical models. Based on the 2D numerical simulations the prototype was produced. The experimental measurements were performed to determine the most appropriate analytical equations for the end winding calculation.

An electrically excited synchronous machine (EESM) is a promising alternative to the permanent magnets synchronous machines being used in the automotive industry. However, the main disadvantage of the EESM with the conventional excitation system with brushes is the presence of slip rings on the shaft, which need regular maintenance. A promising alternative to the conventional excitation system of the EESM is a wireless power transfer (WPT) system. In this paper, we focused on WPT excitation system based on the rotary transformers. First, the model of the EESM in the d-q reference frame with vector control system has been built (based on the parameters of the real machine) and analyzed using MATLAB/Simulink software. Second, the influence of the rotary transformer design parameters on the dynamic performance of the EESM has been investigated. Finally, different topologies of the rotary transformers found in the literature have been analyzed, modeled and compared using an analytical and numerical approach. Based on the obtained results, the most suitable electrical parameters (i.e., geometry parameters, supply frequency, magnetizing and leakage inductance, winding resistance and efficiency) of the rotary transformer have been identified and implemented into the d-q model of EESM.

This paper presents a seamless parametrization procedure for building of the electric and thermal model of DC/AC inverter, connected into a multi-physical inverter model as well as the stand-alone electromagnetic and thermal model of an electrical machine. Both of them are integrated into a single multi-physical electric machine model. The multiphysical models are further interconnected on system level allowing to study the thermal behavior of the components. The importance of multi-physical coupling of the vehicle drive train components (electrical and thermal coupling of electric machine and inverter) is shown through the temperature comparison of de-coupled and coupled thermal models.

In this article, the influence of the rotary transformer design parameters on the dynamic performance of the electrically excited synchronous machine (EESM) has been investigated. The model of EESM in the d-q reference frame with the control system has been built and analyzed using Matlab/Simulink software. The main electrical parameters of the rotary transformer were identified and implemented into the equivalent circuit model of EESM based on the parameters of the real machine. Based on the proposed model, the most suitable design parameters for the wireless excitation system were obtained.

The quality and efficiency of electrical machines are key factors towards improvement of the drive performance. Manufacturing processes have a significant impact on the efficiency of electrical machines. There are different manufacturing techniques such as mechanical cutting, laser cutting, electrical discharge machining etc. Each cutting techniques may cause a deformation near edges of the cutting area that may severely affect the properties of the B-H curve of the ferromagnetic materials. Thus it is important to predict approximately the extension of the damaged area. In this study we have developed an approach based on finite element method using COMSOL Multiphysics simulation software to evaluate the deformation caused by laser cutting on the edges of the ferromagnetic material.

The main purpose of this paper is to analyze and examine the thermal effects caused by the stator end-winding of an induction machine using the numerical computational fluid dynamics (CFD) modeling approach. The study was focused on the heat transfer phenomena between the end-winding and the cooling air inside the end-cap region of interest. Based in the CFD simulation results the heat transfer coefficients between the end-windings and the region of the cooling air and between the cooling air region and the end-cap were determined. The obtained results are validated with the results from the literature. The calculated heat transfer coefficients are important parameters for more accurate thermal analysis of induction machines using lumped-parameter thermal network.

The paper investigates different stator configurations of the switched reluctance motor (SRM) in order to mitigate the electromagnetically-exited audible noise and vibrations. Natural frequencies of different SRM stator configurations are analyzed by virtue of the modal analysis theory. A three-dimensional numerical model of the SRM stator geometry is set up by using the finite element method. The magnetic flux and surface force distribution, responsible for the mechanical vibrations giving rise to an electromagnetically-exited audible noise are calculated and analyzed. Based on the investigation results, the paper proposes a solution on how to select an appropriate stator configuration in order to increase its natural frequencies beyond the resonant operational frequency and, thus, to mitigate the resulting audible noise and vibration.

Laser cutting is one of the very well-known techniques to manufacture electrical machines. The edges of the stator and rotor lamina influenced by the laser cutting become degraded areas after the cutting process. The B-H curve of the ferromagnetic material are deteriorated because of the laser cutting as well. In this paper, we present the state of the art for the laser cutting and thermal influence on the electrical machine characteristics. As well as the novel approach for the electrical machine properties modelling, including technology-thermal-magnetic cross effect.

This paper investigates mechanical vibrations of an interior permanent magnet (IPM) synchronous electrical motor designed for a wide range of speeds by virtue of the modal and rotordynamic theory. Mechanical vibrations of the case study IPM motor components were detected and analyzed via numerical, analytical and experimental investigation. First, a finite element-based model of the stator assembly including windings was set up and validated with experimental and analytical results. Second, the influence of the presence of the motor housing on the natural frequencies of the stator and windings was investigated by virtue of numerical modal analysis. The experimental and numerical modal analyses were further carried out on the IPM rotor configuration. The results show that the natural frequencies of the IPM rotor increase due to the presence of the magnets. Finally, detailed numerical rotordynamic analysis was performed in order to investigate the most critical speeds of the IPM rotor with bearings. Based on the obtained results, the key parameters related to mechanical vibrations response phenomena, which are important when designing electrical motors with interior permanent magnets, are provided. The main findings reported here can be used for experimental and theoretical mechanical vibration analysis of other types of rotating electrical machines.