Armature Windings Research Articles

Development of Temperature Calculation for Armature Windings of Turbine Generators with Circulating Currents and Strands Transposition

Development of Temperature Calculation for Armature Windings of Turbine Generators with Circulating Currents and Strands Transposition

Structure of software and hardware module for research of DC electrical machines. Part 1

The structure of a hardware and software complex for the study of DC electric machines and a mathematical model of its electromechanical part taking into account the influence of temperature on the resistance of the armature winding have been developed. The hardware and software complex is implemented on the Arduino Uno board. A distinctive feature of which is the modular structure, which allows conducting research on DC electric machines in various operating modes (start-up, armature speed control, reversing, braking). In addition, it is possible to implement various laws of changing the load moment. For this purpose, the hardware and software module include the studied and load DC electric machines, which are mechanically connected to each other by means of a coupling and operate in motor and generator modes, respectively. The proposed model makes it possible to describe electromagnetic processes in DC electric machines taking into account the influence of temperature on the resistance of the armature winding, as well as overheating of individual parts of the electric machine. The proposed hardware and software module can find practical application in research laboratories in the study of DC electric machines in various operating modes.

The Study of the Balancing Process for Starting Rotors in Heavy-Duty Vehicles: An Industrial Application

In the heavy-duty vehicle industry, unbalance in the armature is one of the most common problems affecting starters’ performance and durability. This research presents a comprehensive study to improve the balancing process for starting rotors in heavy-duty vehicles. The complete manufacturing process of armatures was analyzed to understand the contribution of assembly processes to unbalancing. The analysis revealed that the primary factor leading to high unbalance in these parts is the misalignment of conductors within the armature winding. During assembly, these conductors experience axial movements, resulting in non-uniform mass distribution and causing unbalanced values ranging from 150 to 350 g·mm. These values surpass the permissible limit, making rectification during the balancing process at the end of the assembly impossible. Consequently, a novel alignment tool was designed to address this issue, significantly reducing the effect and achieving the maximum allowable unbalance of 100 g·mm. This allowed the balancing machine used in the process to correct the initial unbalance of the reinforcements in a single work cycle, improving operation efficiency by about 15%.

Maximizing torque per volume index for SHESM based on two-dimensional method and meta-heuristic optimization algorithms

In this paper, a permanent magnet synchronous machine (PMSM) with an auxiliary winding (AW) on the rotor is analyzed by two-dimensional approach. This PMSM with AW (AWPMSM) can be used in many applications such as propulsion system, aircraft and traction because it includes rotor flux control capability. First, the magnetic field in different parts of AWPMSM is calculated based on Maxwell equations. Then, as a consequence of the magnetic field, the torque components, including cogging, reluctance, electromagnetic and instantaneous torque are computed. Next, torque-speed characteristic has been investigated. This AWPMSM can be located in the flux weakening mode in two ways, first one is to attenuate the rotor field by changing the direction of the AW field and the other one is to adjust the armature current angle, both of them have been investigated. After that, the overload capability and temperature effects have been analyzed. Finally, using the meta-heuristic algorithms such as genetic algorithm, particle swarm optimization, differential evolution and teaching learn base optimization the dimensions of AWPMSM and the initial angle of the rotor are determined in such a way that the torque-to-volume ratio is maximized. The influences of the type of armature winding and the magnetization patterns have also been investigated. The results obtained by the two-dimensional method have been confirmed numerically.

Magnetic Resonance Imaging-Compatible Electromagnetic Actuator: Design and Tests

This paper presents the detailed design, construction and tests of a protype iron-free MRI-compatible electromagnetic actuator. The originality of this proposal lies in the use of the homogeneous static magnetic field B0, present in the MRI bore, to ensure the electromechanical energy conversion. The armature is composed of three rectangular coils in a three-phase arrangement, which makes the actuator very light-weight and compact. The operating principle is that of an AC synchronous motor with a rotating armature. In order to design the actuator, a 3D analytical electromagnetic model is developed to predict the magnetic field produced by the armature winding. Then, a 3D finite element (FE) computation is performed to validate the analytically calculated magnetic field. The developed analytical model is then inserted into an optimization routine based on Genetic Algorithms (GAs) to obtain the prototype dimensions to be realized. Finally, the prototype is constructed and tested inside an MRI research scanner. The results indicate that the reduction in the Signal-to-Noise Ratio (SNR) and the geometrical distortion are less than 5% when the actuator is powered with a current of 10 times the rated one and when it is located very close to the subject to be imaged.

AC Loss Estimation Method for REBCO Superconducting Tapes in AC+DC Fields for Field Windings in Fully Superconducting Synchronous Machine for Electric Aircraft

Abstract The estimation of AC loss in REBa2Cu3O y (REBCO; RE = rare earth, such as Y, Eu, and Gd) superconducting tapes within superconducting synchronous motors and generators for electric aircraft is imperative during the design stage phase to optimize efficiency and cooling considerations. Our previous studies clarified the AC loss characteristics, focusing on estimating the AC loss in armature windings. While the magnetic field applied to the armature windings is exclusively as an AC field, the field windings are subject to a composite field comprising both AC and DC components. Notably, the amplitude of the AC component is markedly smaller than the magnitude of DC component. This study experimentally investigated to consider the AC loss properties in field windings. The experimental results were as follows: When subjected to operational conditions of field windings within synchronous motor and generator, the AC loss increased with the DC field strength. This property is attributed to a reduction in the critical current induced by the external field. Hence, we modified the method for estimating AC loss. Subsequently, we validated the effectiveness of the modified method.

Thermal analysis of sinusoidal doubly salient Electro-Magnetic Machine with distributed magnetomotive forces considering complex heat distribution and material thermal characteristics

Sinusoidal doubly salient electro-magnetic machine with distributed magnetomotive forces has DC excitation and AC armature windings in the same stator slot, which leads to the complicated distribution of heat sources and thermal resistances. One of the keys to design this motor is to estimate the temperature rise accurately. In this paper, the thermal performance of the motor materials at different temperatures was tested. According to the complex structure characteristics, the layered and sub-regional equivalent model of the stator slot is proposed. The model not only uses the material thermal data obtained from experiments, but also considers the complex thermal resistances and AC/DC losses distribution in the slots, as well as the influence of winding and insulation processes on the temperature rise of the motor, which is conducive to obtaining the highest point of the motor temperature and ensuring the calculation accuracy. The 3-D global steady-state temperature distribution of sinusoidal doubly salient electro-magnetic machine with distributed magnetomotive forces is studied, and the temperature rise of each part under different current densities is also analyzed. Finally, the temperature experiment of the prototype is carried out. The experiments show that the accurate loss calculation and thermal parameters make the maximum error between the simulation model and the actual measurement is 3.8 °C. The results not only guide the selection of reasonable armature and excitation winding current density of sinusoidal doubly salient electro-magnetic machine with distributed magnetomotive forces, but also provide data and experience support for temperature estimation of motors with complex winding distribution.

Influence of DC-Field Current on Short-Circuit Current in Variable Flux Reluctance Machine

DC-field windings of variable flux reluctance machine are wound on the same teeth with armature winding, which increases the short-circuit probability among the armature and field windings. Therefore, in this article, the various short-circuit faults of single phase, phase-to-phase, single field and phase-to-field are illustrated, and the influence of dc-field current on short-circuit current (SCC) and braking torque (BT) with consideration of initial rotor position are investigated. The SCC with dc-field current is analytically established, where the SCC and BT in transient and steady states are analyzed. The maximum SCC and BT are comprehensively compared by finite element method. It is found that the influence of dc-field current on the SCC and BT under transient conditions can be neglected. However, when the machine under un-saturated conditions, the SCC in steady states is associated with the saturation of iron core, i.e., the more saturated of the core excited by dc-field current in prefault, the smaller of the SSC in post fault. Both the SCC and BT are accompanied by the 12/14-pole VFRM prototype experimental verification.

Diagnosis of Open-Circuit Faults in DC-Field Excited Variable Flux Reluctance Machine Utilizing Armature and Field Currents

More electric aircraft has high reliability requirements, and the DC-field excited modular variable flux reluctance machine (MVFRM) is its key component. The MVFRM has both armature and field windings, in which AC (alternating currents) and DC (direct currents) are supplied. Hence, traditional fault diagnosis is not applicable for MVFRM. In this paper, the diagnostic methodology for open-circuit faults in both windings is proposed by utilizing armature currents and field currents. Based on the internal relationship between the armature currents with <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">αβ</i> -axis currents and the field currents, the characteristics and diagnosis mechanisms of armature winding and field winding open-circuit faults are analyzed. The per-unit threshold setting method is adopted to improve the rapidity of the algorithm without reducing robustness. The rapidity and effectiveness of the fault diagnosis algorithm are verified by different types of open-circuit fault diagnosis experiments. Furthermore, the robustness of the fault diagnosis algorithm is verified by the variable speed and different loads of open-circuit fault diagnosis experiments.

Preliminary Assessment of New Armature Winding Concepts for High-Speed Superconducting Motors

Preliminary Assessment of New Armature Winding Concepts for High-Speed Superconducting Motors

Electromagnetic Performance Analysis of Dual-Three-Phase Dual-Rotor Flux-Switching Permanent Magnet Machines

In this paper, a novel dual-three-phase dual-rotor flux-switching permanent magnet (PM) (DRFSPM) machine, building upon conventional FSPM machines, is proposed, where the stator is equipped with dual PMs and dual armature windings, enabling it to operate in various working modes and provide fault tolerance in the event of PM or armature winding faults. Depending on the magnetization directions of the PMs, the proposed DRFSPM machine’s structure can be categorized as 6N-DRFSPM or NS-DRFSPM. In order to assess the electromagnetic performance of the proposed DRFSPM machines with two different magnetizing modes, the topology and operating principle of the two DRFSPM machines are introduced first. Then, the no-load air-gap flux density of the two proposed machines is investigated for a more optimized and purposeful design. Finally, a comparison of the electromagnetic performance between the two proposed DRFSPM machines is conducted by finite-element analysis (FEA), and the FEA-predicted results indicate that the proposed 6N-DRFSPM machine outperforms the NS-DRFSPM machine, as it exhibits a larger back-EMF and average torque and a smaller cogging torque and torque ripple.

Torque Ripple Reduction in Brushless Wound Rotor Vernier Machine Using Third-Harmonic Multi-Layer Winding

This article aims to realize the brushless operation of a wound rotor vernier machine (WRVM) by a third-harmonic field produced through stator auxiliary winding (X). In the conventional model, a third-harmonic current is generated by connecting a 4-pole armature and 12-pole excitation windings serially with a three-phase diode rectifier to develop a pulsating field in the airgap of a machine. However, in the proposed model, the ABC winding is supplied by a three-phase current source inverter, whereas the auxiliary winding (X) carries no current due to an open circuit. The fundamental MMF component developed in the machine airgap creates a four-pole stator field, while the third-harmonic MMF induces the harmonic current in the specialized rotor harmonic winding. The rotor on the other side contains the harmonic and the field windings connected through a full-bridge rectifier. The electromagnetic interaction of the stator and rotor fields generates torque. Due to the open-circuited winding pattern, the proposed machine results in a low torque ripple. A 2D model is designed using JMAG-Designer, and 2D field element analysis (FEA) is carried out to determine the output torque and machine’s efficiency. A comparative performance analysis of both the conventional and proposed topologies is discussed graphically. The quantitative analysis of the proposed topology shows better performance as compared to the recently developed third-harmonic-based brushless WRVM topology in terms of output torque and torque ripples.

Operational Analysis of an Axial and Solid Double-Pole Configuration in a Permanent Magnet Flux-Switching Generator

There are two main beneficial characteristics that doubly salient permanent magnet (PM) electrical machines present for aircraft applications: armature windings and PMs excitation sources placed on the stator side (maintenance and thermal management), and having a clear-cut rotor without PMs or excitation windings (vulnerable at high speeds due to associated centripetal mechanical stresses). Within this framework, a doubly salient permanent magnet (DSPM) generator was conceived by optimizing the stator size and rotor structure to minimize the torque ripple and maximize the root-mean-square (RMS) voltage value per turn of each generator phase. Firstly, a comparison between the 2D and 3D finite element method (FEM) models is made considering the results of 3D finite element analysis (FEA) as our benchmark in order to understand the accuracy of the 2D results against our benchmark model, the 3D one. A multi-objective design strategy based on a 2D FEA is made, it is set to have characteristics closest to optimal for a Boeing 767 turbine, that is, the necessary electromotive force for a required power of 90 kW at 3000 rpm, feeding a simplified Boeing 767 electrical power distribution system. The results show that the machine could not deliver the required power at 3000 rpm since the 2D FEA demonstrates that the 2D model gives optimistic results when compared with the 3D FEM model. However, with a 3D FEA of the machine feeding the aircraft load, it was seen that the machine’s efficiency is 92%, suggesting that this machine can be a plausible solution.

ДОСЛІДЖЕННЯ ЕЛЕКТРОМАГНІТНИХ ТА МЕХАНІЧНИХ ПРОЦЕСІВ АСИНХРОННО-СИНХРОННОГО ЕЛЕКТРОМЕХАНІЧНОГО ПЕРЕТВОРЮВАЧА В РЕЖИМІ НЕРОБОЧОГО ХОДУ

A two-dimensional circuit-field model of non-stationary electromagnetic and mechanical processes of an induction-synchronous electromechanical converter has been developed. It allows establishing the relationship between electro-magnetic processes in the circuit and 2D-field parts of the model, taking into account the features of the construction of its armature and rotor windings through their schematic implementation, and ensuring switching with elements of con-ventional and semiconductor power systems. Electromagnetic and mechanical processes in idle mode have been inves-tigated using numerical modeling methods, considering the combined interaction of the coupled induction and synchro-nous parts in a single active part of the electromechanical converters. The presence of self-synchronization properties for induction -synchronous electromechanical converters has been demonstrated, wherein asynchronous starting is provided with subsequent synchronization of its rotor into synchronism in idle mode without excitation, and the condi-tions for their occurrence are explained. The relationships between the idle current and excitation current have been established, determining the operation of the synchronous part of the induction-synchronous electromechanical con-verter in underexcited, normally excited, and overexcited modes. It has been proven that in underexcited and normally excited modes, its synchronous part operates as a reactive power compensator, while in the overexcited mode, it oper-ates as a generator. Experimental studies confirm the adequacy and accuracy of numerical implementation, as well as the correspondence to electromagnetic processes during the operation of the induction-synchronous electromechanical converter in idle mode. References 14, figures 11.

Increasing the Energy Efficiency of Traction Electric Drives of Direct Current

Purpose. The work is aimed at improving the energy efficiency of direct current traction electric drives of electric transport by introducing transistor pulse width converters (PWC) with an optimal switching frequency to minimize total electrical losses in the electric drive. The electrical losses of traction electric drives consist of electrical losses in the armature winding and in the PWC transistors. Methodology. To study the dependence on the switching frequency of transistors, the electrical losses in the armature winding and PWC transistors are divided into two parts: static losses from the direct current component of the current and dynamic losses, i.e., losses in the armature winding from harmonic current components and losses in the transistors from transient switching currents. Since the dynamic electrical losses in transistors increase with increasing frequency and decrease in the armature winding, it is necessary to find the optimal PWC co-mutation frequency at which the total dynamic losses in the traction electric drive will be minimal. The goal of increasing energy efficiency in a traction electric drive is achieved by determining the dependence of dynamic electrical losses in the armature winding on the switching frequency of the PWC and computer modeling of the transistor electric drive. Findings. It is found that the relative dynamic electrical losses in the armature winding in the case of polyharmonic power supply are equal to the square of the armature current ripple coefficient. An algorithm for determining the optimal switching frequency of the PWC is developed: 1) the dependence of dynamic electrical losses on the switching frequency of transistors is determined experimentally on computer models of the motor and PWC; 2) the graph of the dependence of total dynamic electrical losses of the transistor electric drive on the time-tothe point of minimum losses, which corresponds to the optimal frequency value, is determined. Originality. For the first time, the authors obtained an analytical expression for the relative dynamic electrical losses in the armature windings, which are equal to the square of the armature current ripple factor. Practical value. Establishing the optimal switching frequency of the PWC according to the developed methodology reduces electrical losses in traction electric drives, i.e., increases their energy efficiency.

Design of an Integrated Magnetorheological Fluid Brake Axial Flux Permanent Magnet Machine

This paper presents the design and performance of an integrated magnetorheological fluid brake axial flux permanent magnet (IMRFB-AFPM) machine with two switchable operation modes: rotation and brake modes while the machine has two kinds of windings: armature winding in axial stators and braking winding in radial stator. In rotation mode, this machine is equal to a conventional AFPM machine with high torque density. When switching to brake mode, MR fluid is excited by braking winding and applies large damping stress to the rotor to brake it. This paper illustrates the machine topology, operation principles, and design flow of the proposed machine. Then, this paper analyzes the torque generation mechanism in two modes and applies parameters optimization to improve the torque capability of each mode. Due to the independence of the magnetic flux path, the parameters optimization is divided into two parts: AFPM part and IMRFB part. After the optimization process, the electromagnetic performances of the optimal IMRFB-AFPM machine are analyzed by finite element (FE) analysis. Finally, a prototype machine with the optimal geometric parameters is manufactured and verified experimentally. The experiment results agree well with FE analysis results, validating the feasibility and practicability of the proposed design.

A Magnetic-Geared Machine With Improved Magnetic Circuit Symmetry for Hybrid Electric Vehicle Applications

Magnetic-geared machine (MGM) has been widely investigated as the power split device for hybrid electric vehicles with the inherently high-integration of multi-mechanical ports. It is revealed that the magnetic circuits of armature winding in MGM are essentially asymmetrical for different phases under the magnetic field modulation effect. This inevitably results in unbalanced phase back electromotive force (EMF) waveforms, severe torque ripples, acoustic noise, and difficulty for precise control. To alleviate the asymmetry problem, a generic winding design model is presented for MGMs in this paper, which allows for consideration of all potential winding configurations. Firstly, a novel back EMF harmonic factor is proposed to account for both the harmonic content and asymmetric level in MGM. The genetic algorithm (GA) is further employed to optimize the winding in terms of minimizing the back EMF harmonic factor, armature magnetomotive force harmonic contents, and phase winding resistance. The proposed winding layout exhibits superior filtering capability for three-phase asymmetric magnetic field harmonics. As compared with the conventional integral-slot distributed winding, the MGM with the proposed winding exhibits improved back EMF waveform symmetry, suppressed torque ripple, and reduced core losses. Finally, an experimental prototype is manufactured to validate the effectiveness of asymmetric magnetic field suppression for MGMs. The results show the investigated winding design method is an effective solution to the asymmetric issue of MGMs, paving the way to research opportunities for further improvements.

A Mathematical Model for Wound Field Switched Flux Machine Considering Inductance Harmonics of Field and Armature Windings

A Mathematical Model for Wound Field Switched Flux Machine Considering Inductance Harmonics of Field and Armature Windings

Диагностика неисправностей тягового электродвигателя электропоезда ЭД9Т методом спектрального анализа тока в обмотке якоря

The results of the research in the sphere of the efficiency increase of functioning of the traction electric motor of the ED9T electric train have been presented. Smooth and sustainable railway transport operation depends greatly on the reliability of the traction motor of the ED9T electric train and its efficiency of use. The most widespread damages in the armature winding of the traction motor of ED9T electric train are violations of the terms of the armature commuting, inter-winding faults because of the damage of the insulation of coil turns, closure of winding on the case («ground») and double closures on the ground. The authors offered a logarithmical spectral method of diagnostics allowing to determine malfunctions on the results of mathematical spectrogram processing for rapid clarification of the faults of the armature windings of the traction electric motor.

Measurement and Analysis of Rotating Magnetic Field in Multiphase Annular Brushless Exciters With Armature Winding Short-Circuit Faults

Measurement and Analysis of Rotating Magnetic Field in Multiphase Annular Brushless Exciters With Armature Winding Short-Circuit Faults