Tayfun Gundogdu

This article presents the design considerations and a parametric analysis of a limited-angle wound rotor resolver (LAWRR) with high precision. LAWRRs are extensively employed in motion control systems requiring limited rotation, such as missile guidance and gimbal systems, radars, missile seekers, and gyro-stabilized electro-optical systems. The LAWRR’s wound rotor has a limited rotation of 0°–360° and features an excitation (EXC) winding on the rotor with signal windings on the stator. Operating, geometric, and magnetic properties that affect the accuracy are determined. To reveal the influence of key operating and geometric design parameters on accuracy, a number of parametric analyses, including EXC current and frequency, air-gap and stack lengths, rotor skew angle, split ratio, and slot dimensions, were carried out employing the 2-D finite element analysis (FEA) method. The most prominent and critical design variables affecting the angular position error have then been determined. Time-averaged, peak-to-peak, minimum, and maximum position errors were calculated for accuracy analyses. Finally, experimental measurements on a prototyped LAWRR are employed to validate the numerical analysis results.

This paper investigates the torque generating capabilities and performance comparison of induction machines (IM) and interior-permanent magnet (IPM) machines for electric vehicle (EV) traction applications. Electromagnetic performance characteristics, such as torque, torque ripple, air-gap flux density, etc. are quantitatively compared by changing the level of electric loading. Other performance metrics such as saturation factor, power losses, efficiency, and so on, as well as the flux-weakening capability and efficiency map have also been compared. For calculations of the electromagnetic performance characteristics, 2D time-stepping finite element analysis (FEA) has been employed. It has been revealed that due to the reduction in torque components of IPM machine as a consequence of magnet demagnetization, it cannot generate toque as high as IM under overloading operating conditions. A thorough review of the literature on comparative studies on the electrical machines used in EV or Hybrid EV (HEV) applications is also included.

Bu çalışmada; dış rotorlu ve yüzeye monte mıknatıslara sahip bir Vernier makinanın tüm geometrik parametrelerinin performans karakteristiklerine olan etkisi detaylı bir şekilde incelenmiştir. Bu çalışmanın amacı, düşük hız yüksek moment uygulamalarında kullanılan Kalıcı Mıknatıslı Vernier makinalar (KMVM) için mıknatıs, diş ve diş açıklığı kalınlık ve genişlikleri, hava aralığı genişliği, rotor dış çaplarının iç çapına oranı (bölünme oranı), şaft çapı gibi temel tasarım parametrelerinin moment, moment dalgalılığı, verim ve zıt EMK’ya olan etkisi inceleyerek genel bir tasarım kılavuzu geliştirmektir. KMVM’ların tasarım ve çalışma prensibi kısaca anlatılmış ve düşük moment dalgalılığına karşın yüksek moment veren oluk/kutup kombinasyonun nasıl seçilmesi gerektiği üzerinde durulmuştur. Akabinde, tasarım parametreleri tanıtılmış ve makinanın küçük güçlü rüzgâr türbini uygulamalarında kullanılacağı düşünülerek, her geometrik parametrenin moment ve verimin yanı sıra, terminal gerilimi hakkında detaylı bilgi veren zıt EMK dalga biçimi de parametrik olarak analiz edilmiştir. Moment, verim ve endüklenen gerilimi en çok etkileyen geometrik tasarım parametreleri belirlenmiş ve parametrik olarak en iyi tasarım elde edilmiştir. Analizler zaman adımlı, doğrusal olmayan, iki boyutlu sonlu elemanlar yöntemi (SEY) tabanlı bir program ile gerçekleştirilmiştir.

This paper investigates the flux-weakening characteristics and transient response of a dual winding interior permanent magnet (DWIPM) machine designed using the 2010 Toyota Prius IPM Machine specifications. In order to thoroughly adjust the main flux, dual windings are fed by separate identical inverters. Thus, significantly high-torque for high-speed requirements can be simply achieved by making one of the inverters open-circuited. Transient response of the DWIPM machine, including torque and current pulsations, occurring during normal drive or deactivation of one of the inverters has also been investigated for different operation modes. The flux-weakening performance characteristics of the proposed DWIPM machine have been compared with those of its single-fed counterpart in order to highlight the benefits and drawbacks of the dual-winding topology. The steady-state performance characteristics, torque/speed and power/speed curves, efficiency maps, machine transient response, different machine design options with various numbers of turns per phase and current amplitudes, and the importance of the electromagnetic coupling between dual windings have all been addressed. For transient and steady-state analyses, 2D, nonlinear, time-stepping finite element method (FEM) has been employed. It has been revealed that the proposed DWIPM machine exhibit significantly improved flux-weakening characteristics, particularly high-power at constant power region and high efficiency at constant torque region, and quite low current and torque pulsations occurring during operation mode change.

In this paper, an interior permanent magnet (IPM) machine having two sets of windings with different number of turns is developed to improve the limited flux-weakening (FW) capability and efficiency, simultaneously. The flux-adjustable range appears to be somewhat limited because of the limited maximum inverter voltage and high magnetic saturation, which degrades the FW capability. To address its restricted FW capability, a unique winding-switching concept is introduced, in which auxiliary coils with lower turns alternately function as the secondary armature winding, resulting in flux-linkage reduction within the same phase. Winding topologies, design considerations, the FW principle, and FW computations have all been addressed. To validate the feasibility of the proposed FW enhancement strategy, a co-simulation procedure based on the 2D finite element method (FEM) and MatLab codes is used to determine the steady-state and FW performance characteristics of IPM machines with various winding topologies. All steady-state and FW performance characteristics of the conventional IPM machine and the proposed IPM machines have been compared quantitatively. Furthermore, to ensure the accuracy of the analytical and numerical calculations provided in this study, the predicted efficiency map of the original Toyota Prius 2010 IPM machine is validated using the efficiency measurements provided.

The limited-angle resolver is commonly employed instead of an optical encoder as a position sensor in medical, special industrial, custom robotics, transportation and military applications owing to their reliability, low cost, and ability to work steadily in harsh and contaminated environments. In the design and optimization of resolvers, achieving high precision while maintaining a simple manufacturing process for mass production is a big challenge. This study proposes a systematic method for the determination of slot and pole number combinations of limited-angle wound rotor resolvers (LAWRRs) for high accuracy and easy manufacturability. A set of stator and rotor slot numbers ranging from 8–64 for 2 and 4 poles, which are suitable for concentric winding (CW) topology, have been considered. For high accuracy, number of turns distribution waveforms and their total harmonic distortion (THD) percentages are investigated. In addition, for easy manufacturability, low slot number combinations providing high accuracy are determined and the feasibility of employing solid core instead of laminated core is examined. Analytical calculation results of the proposed configurations are validated utilizing a two-dimensional time-stepping finite-element analysis (2D-FEA). Finally, in order to experimentally validate the methodology and analyses, two prototypes with low and high slot numbers are manufactured and tested.

This paper investigates and compares the torque-generating capabilities and electromagnetic performance of advanced non-overlapping winding induction machines (AIM), conventional induction machines (CIM), and interior-permanent magnet (IPM) machines for electric vehicle (EV) applications. All investigated machines are designed based on the specifications of the Toyota Prius 2010 IPM machine. The steady-state and flux-weakening performance characteristics are calculated by employing the 2D finite element method and MatLab, and the obtained results are quantitatively compared. Furthermore, the torque-generating capabilities of three machines are investigated for different electric loadings, and the machine having the highest torque-generating capability is determined as AIM. Moreover, the major parameters affecting the torque-generating capability, such as magnetic saturation and magnet demagnetization, are examined in depth.

In this study, the comprehensive design and analysis of a limited-angle wound rotor resolver (LAWRR) with high precision are presented. The effect of two major design parameters, including stator and rotor number of turns combinations, as well as the transformation ratio, on angular position accuracy is investigated. To determine the optimal number of turn combinations of LAWRRs with concentric windings (CWs), a simple analytical method consisting of calculating the total harmonic distortion (THD) percentage of the winding distribution waveform is employed. The fundamental operating principle and parametric analyses are carried out using finite element analysis (FEA), which is then followed by verification of the analytical calculations and determination of the optimal number of turn combinations. Moreover, the cross-correlation effect of the signal (stator) and excitation (rotor) winding configurations has been considered. Time-averaged, peak to peak, and maximum position errors were calculated for accuracy analyses. Finally, a prototype is built and tested to validate the analytical and numerical analyses, as well as the main parameters and angular position error.

This paper presents a comprehensive design optimization and performance improvement guidelines for induction machines (IMs) having advanced nonoverlapping windings (ANWs). The effectiveness of various optimization approaches, such as individual optimization and single- and multi-objective global optimization using the Genetic Algorithm (GA), has been studied. To minimize the potential drawbacks of high bar copper loss, high torque ripple, and low power at high speed due to high magnet-motive force (MMF) harmonics of nonoverlapping windings (NWs), two different performance improvement approaches have been utilized: (a) to redesign the rotor structure to reduce the parasitic effects such as torque ripple and additional bar copper losses due to air-gap flux density harmonics; (b) to increase the stack length to improve the torque at the constant-power region. It has been revealed that the proposed ANW IMs with bridges in their rotor openings, particularly with u-shaped bridges, show better performance in terms of torque ripple, bar copper loss, and bar current density. By using the proposed design method, an advanced IM (AIM) can achieve a 5.3% higher efficiency with ~34% shorter total axial length, compared to its conventional IM (CIM) counterpart with integer-slot distributed windings (ISDWs). A time-stepping 2-D finite element analysis (FEA) based nonlinear magnetic field solution program has been employed to perform all the parametric analyses, optimizations, and evaluate the optimal solutions and improved designs. Moreover, in order to show the reliability of the FEA predictions performed in this study, the FEA predictions of globally optimized CIM are validated by experimental measurements.

This paper presents a detailed analysis and design guidelines for advanced nonoverlapping winding induction machines (AIMs) with coil-pitch of two slot-pitches by considering some vital empirical rules and flux-weakening characteristics. The aim of the study is to develop a type of new winding and stator topology for induction machines (IMs) that will lead to a decrease in total axial length without sacrificing torque, power, and efficiency. The key performance characteristics of the improved AIMs are investigated by 2D time-stepping finite element analysis (FEA) and compared with those of IMs having fractional and conventional overlapping and nonoverlapping windings. Compared with the conventional overlapping winding counterpart of the AIM, a ~25% shorter axial length without sacrificing torque, output power, and efficiency is achieved. In addition, the influences of major design parameters, such as stator slot, rotor slot and pole numbers, stack length, number of turns per phase, machine geometric parameters, etc., on the flux-weakening characteristics are investigated. It has been concluded that the major design parameters have a considerable effect on the electromagnetic performance. However, among those parameters, the influences of pole number and stack length together with the number of turns on flux-weakening characteristics are significant.