The paper is a presentation of an analysis concerning performance of a 12/8 dual-channel switched reluctance motor (DCSRM). Formulas constituting a base for a non-linear mathematical model of DCSRM are presented. Simulation and laboratory tests were carried out for the motor operating in the dual-channel and single-channel mode. The results of the field theory-based calculations are presented in the form of fluxes in individual phases expressed as functions of currents and a rotor position angle. The results of the computer simulations are shown as the static characteristics of fluxes and the torque as well as voltage, current, and torque waveforms. The results of the laboratory tests are also presented.

This paper considers a Brushless Direct Current (BLDC) machine prototype with six poles and 36 stator slots including a three phase double-layered distributed winding. Presented modifications of rotor construction are identified in order to achieve the best possible compromise of eddy-current losses and cogging torque characteristics. The permanent magnet (PM) eddy-current loss is relatively low compared with the iron loss; it may cause significant heating of the PMs due to the relatively poor heat dissipation from the rotor and it results in partial irreversible demagnetization. A reduction in both losses is achieved by magnet segmentation mounted on the rotor. Various numbers of magnet segmentation is analysed. The presented work concerns the computation of the no-load iron loss in the stator, rotor yoke and eddy-current loss in the magnets. It is shown that the construction of the rotor with segmented magnets can significantly reduce the PM loss (eddy-current loss). The eddy-current loss in PMs is caused by several machine features; the winding structure and large stator slot openings cause flux den sity variations that induce eddy-currents in the PMs. The effect of these changes on the BLDC motor design is examined in order to improve the machine performance. 3-D finite-element analysis (FEA) is used to investigate the electromagnetic behaviour of the BLDC motor.

This paper presents a finite element investigation into the proximity losses in a high-speed permanent magnet (PM) machine for traction applications. A three-dimensional (3D) finite element analysis (FEA) is employed to evaluate and identify the endwinding contribution into the overall winding power loss generated. The study is focused on the end-winding effects that have not been widely reported in the literature. The calculated results confirm that the end-winding copper loss can significantly affect the eddycurrent loss within copper and it should be taken into account to provide reasonable prediction of total losses. Several structures of the end-winding are analyzed and compared in respect to the loss and AC resistance. The results clearly demonstrate that the size of the end-winding has a significant impact on the power loss. The calculated results are validated experimentally on the high-speed permanent magnet synchronous machine (PMSM) prototype for selected various winding arrangements.

In the paper, the modified (compared to the classical asymmetric half-bridge) converter for a switched reluctance machine with an asymmetric rotor magnetic circuit was analysed. An analysis for two various structures of switched reluctance motors was conducted. The rotor shaping was used to obtain required start-up torque or/and to obtain less electromagnetic torque ripple. The discussed converter gives a possibility to turn a phase off much later while reduced time of a current flows in a negative slope of inductance. The results of the research in the form of waveforms of currents, voltages and electromagnetic torque were presented. Conclusions were formulated concerning the comparison of the characteristics of SRM supplied by the classic converter and by the one supplied by the analysed converter.

This paper presents the loss-oriented performance analysis of a radial highspeed permanent magnet (PM) machine with concentrated windings for automotive application. The PM synchronous machine was designed for an operating frequency up to 800 Hz. The main aim of this paper is to analyse the selected methods for magnet eddycurrent loss reduction. The first approach to rotor modification regards magnet segmentation in circumferential and axial directions. The second approach is based on changes in tooth-tips shape of the stator. The best variants of tooth-tip shapes are determined for further investigation, and adopted with a rotor having magnet segmentation. It is found that the machine with a segmented magnet leads to magnet loss reduction by 81%. Further loss reduction by 45% can be realized with the proposed tooth-tip shape. Additionally, owing to the stator and rotor modifications, the main machine parameters are investigated, such as back-EMF, electromagnetic torque, torque ripple and cogging torque. The 2-D and 3-D finite element analysis (FEA) is used for electromagnetic analysis. An experimental approach based on a partially wound stator is employed to verify the 3-D FEA.

Accurate prediction of power loss distribution within an electrical device is highly desirable as it allows thermal behavior to be evaluated at the early design stage. Three-dimensional (3-D) and two-dimensional (2-D) finite element analysis (FEA) is applied to calculate dc and ac copper losses in the armature winding at high-frequency sinusoidal currents. The main goal of this paper is showing the end-winding effect on copper losses. Copper losses at high frequency are dominated by the skin and proximity effects. A time-varying current has a tendency to concentrate near the surfaces of conductors, and if the frequency is very high, the current is restricted to a very thin layer near the conductor surface. This phenomenon of nonuniform distribution of time-varying currents in conductors is known as the skin effect. The term proximity effect refers to the influence of alternating current in one conductor on the current distribution in another, nearby conductor. To evaluate the ac copper loss within the analyzed machine a simplified approach is adopted using one segment of stator core. To demonstrate an enhanced copper loss due to ac operation, the dc and ac resistances are calculated. The resistances ratio ac to dc is strongly dependent on frequency, temperature, shape of slot and size of slot opening.

In this paper, an analysis of the properties of a switched reluctance motor (SRM) 8/6 in an extended constant power range is presented. The typical constant power range to constant torque range ratio is between 2 and 3. In the case of machines designed as an electric vehicle drive, it is important to maximize this ratio. In the case of an SRM, it is possible to achieve this by applying an appropriate control strategy. An analysis of the SRM operation utilizing a modified control algorithm allows control of the maximum value of the motor phase current. As a consequence, using the so-called nonzero initial conditions for the current and flux allows the output power to be maintained in a wide speed range. For the improvement of drive system efficiency, the work of the phase current regulator should be limited to a minimum. The most advantageous work conditions we obtain with single-time current regulator work. Laboratory verification has been performed for selected states of motor work.

This paper presents a comparison of an AC radial flux interior permanent magnet (IPM) motor with the distributed winding (DW) and concentrated winding (CW). From time to time, manufacturers of electric vehicles change the design of electric motors, such changes may include changing the DW into CW and vice versa. A change to the winding in a radial permanent magnet synchronous motor may lead to a change in motor parameters during motor operation and /or change in the distribution of the magnetic field and thermal circuit of the electrical machine. The electromagnetic analysis, efficiency map, mechanical stress, and thermal analysis of the machine with the DW and CW are presented in this paper. This article describes the advantages and disadvantages of selected stator winding designs and helps understand manufacturers’ designers howtheDWandCWplay a key role in achieving the designed motor’s operational parameters such as continuous performance. Analyzing the performance of both machines will help identify their advantages and disadvantages with regard to thermal phenomena, magnetic field and operational parameters of the presented IPM prototypes. Both prototypes are based on commonly used topologies such as 12/8 (slot/pole) and 30/8 (slot/pole) IPM motors consisting of magnets arranged in a V-shape. The AC IPM motor was designed for an 80 kW propulsion system to achieve 170 N·m at a base speed of 4 500 rpm. Modern CAD tools are utilized throughout the numerical computations based on 2-D finite element methods. Selected test data are used to verify and validate the accuracy of finite element models.

Common variable immunodeficiency (CVID) is a primary immunodeficiency disorder related to recurrent infections, as well as a range of non-infectious manifestations including autoimmune and inflammatory disorders. We hypothesized that patients with CVID and different clinical phenotypes would demonstrate alterations in lymphocyte T subsets, including T lymphocytes expressing programmed cell death protein 1 (PD-1), and regulatory T lymphocytes. We performed flow cytometry in two CVID groups: group 1 with infections only, and group 2 with infections and concomitant noninfectious manifestations. Patients were 18–59 years old (mean 35.8 years of age). Increased proportions of CD8+PD-1+ T cells and reduced regulatory T cells were associated with lymphadenopathy. Amount of regulatory T cells correlated with CD8+PD-1+ T lymphocytes (r = 0.54; p = 0.013), and with CRP (r = –0.64; p = 0.004). Forty percent of patients expressed manifestations in addition to infections (group 2), and they had reduction in number of regulatory T cells [8 (3–12) vs. 24 (11–26)/μl; p = 0.034), naive CD4+ T lymphocytes [36 (27–106) vs. 149 (81–283)/μl; p = 0.034], and elevated C-reactive protein (CRP) [5.33 (3.15–8.82) vs. 1 (1–2.16) mg/l; p = 0.003] in comparison to group 1. In conclusion, the amount of CD8+ T cells expressing PD-1 is associated with lymphadenopathy and number of regulatory T cells in patients with CVID. Patients with CVID and non-infectious complications have increased level of inflammation and alterations in regulatory T cells.