Conventional Electric Machines Research Articles

Devlopment of Foot Powered Laundry Machine

This paper presents the design and performance evaluation of a foot powered laundry machine aimed at providing sustainable laundry solutions for households. The proposed design integrates human- powered mechanical energy to drive the washing process, offering an eco-friendly alternative to conventional electric washing machines. The design process involved the selection of appropriate materials, mechanical components, and ergonomic considerations to ensure user comfort and efficiency. Performance evaluation experiments were conducted to assess the washing machine's effectiveness in removing stains, water consumption, and energy efficiency compared to electric counterparts. The results demonstrate the feasibility and potential environmental benefits of pedal-powered washing machines for promoting sustainable living practices.

Peter John Lawrenson. 12 March 1933—27 October 2017

Born in Prescot, Lancashire, Peter Lawrenson rose from relatively humble origins to become a leading figure in the world of electrical motors and generators—first as an academic and latterly as a businessman. Noteworthy research throughout the 1960s quickly earned him a personal chair at the University of Leeds, and for a number of years he was head of department at the university's School of Electrical & Electronic Engineering. He is particularly remembered for pioneering the application of numerical methods to electromagnetic field problems, and for promoting and commercializing the switched reluctance motor, which—via the business, Switched Reluctance Drives Ltd, that he co-founded with research colleagues—was transformed from a laboratory curiosity to a commercially viable and highly efficient alternative to conventional electrical machines. A leading figure in the Institution of Electrical Engineers (IEE, latterly the IET), he also served with distinction as IEE president in 1992.

Comparative analysis of torque-adding wind energy conversion systems with a counter-rotating vs. conventional electric generator

The paper presents a comparative analysis on the steady-state behavior of two counter-rotating wind turbines with same components, where the generator can operate as a counter-rotating (with both a mobile rotor and stator—Case a) vs. conventional (with a fixed stator—Case b) electric machine. These wind energy conversion systems (WECSs) also have two coaxial counter-rotating wind rotors and a one-degree-of-freedom (1-DOF) planetary speed increaser with two inputs and one or two outputs for compatibility with the considered generator. The paper aims at highlighting the efficiency and energy performances of WECSs with a counter-rotating vs. conventional generator by investigating three functional scenarios (A, B, and C) of the two WECS cases (a and b) under the assumption of identical or different counter-rotating wind rotors. A generalized kinetostatic modeling algorithm is first proposed, starting from the general case of WECS with a counter-rotating generator, which allows the establishment of analytical relationships corresponding to speeds and torques at input and output shafts. Numerical simulations of the obtained closed-form model in each scenario highlighted the influence of the constructive parameters on WECS performances, as well as the energetic superiority of WECS, with a counter-rotating generator (Case a) vs. conventional generator (Case b): higher efficiency by 1.2% and more output power by 1% (Scenario A) to 5.5% (Scenario C).

A Permanent Magnet Brushless Doubly Fed Electric Machine for Variable-Speed Constant-Frequency Wind Turbines

A permanent magnet brushless doubly-fed electric machine is presented in this paper. This machine is developed for variable-speed constant-frequency wind energy generation applications. Differing from conventional doubly-fed electric machines based on induction machines, a permanent magnet rotor provides the magnetic field excitations for both the control winding and the power winding in the presented machine. The operating principle of the presented machine for the variable-speed constant-frequency operation is revealed in detail. Compared to a counterpart machine, the presented machine exhibits significantly improved back- electromotive force, torque/power density, torque per magnet volume, efficiency, etc. Finally, a proof-of-concept prototype of the presented machine is fabricated, and the corresponding experimental results are provided to verify the fact that the presented machine is capable of achieving the variable-speed constant-frequency function.

Superconducting Electromagnetic Launch Machine System for Aerospace Applications

The aerospace industry is constantly experimenting with innovative technologies to improve efficiency, effectiveness and sustainability. The use of superconducting machines emerged as a promising solution to address the growing demands of Aerospace applications. Superconducting machines offer significant advantages such as higher power density, reduced weight and improved efficiency compared to conventional electrical machines. However, efficient cooling methods are critical to maintain superconducting materials at low-temperature operating conditions. This abstract provides a comprehensive overview of superconducting machines and their associated cooling systems designed for space applications. A superconducting machine uses high-temperature superconductors to achieve near-zero electrical resistance, enabling high currents to be transmitted with low energy losses. This feature allows development of lightweight and compact electric propulsion systems contribute to improved fuel efficiency and extended mission capabilities in space vehicles. A cooling system is an important component of a superconducting machine because it ensures that the superconducting materials remain below their critical temperature. Various cooling techniques are being explored, including cryogenic cooling, liquid nitrogen cooling, and cryocoolers. These cooling systems effectively extract the heat generated during engine operation, maintaining the superconducting components in their superconducting state.

FEATURES OF THE FIELD WEAKENING MODE IN А SWITCHED RELUCTANCE MACHINE

The magnetic field weakening mode of electric machines is used in modern drives to extend the drive operational speed range when the power supply voltage is limited. In conventional electric drives, a real or fictitious flux control loop, established in a vector control system by using coordinate and phase transformations of corresponding variables, is used for attenuating the motor magnetic flux. Switched reluctance machines have certain design advantages over conventional electric machines; they feature high reliability and wide control possibilities. However, to realize these possibilities, appropriate control outputs should be generated, the choice of which depends on the operational speed range. Another peculiarity of these machines is that there is no separate magnetic flux stabilization or control circuit. The article considers the specific features pertinent to the switched reluctance machine operation in various speed ranges for adequately taking them into account in control algorithms. The studies were carried out using the electric drive simulation model in the MATLAB Simulink environment. It is shown that during the electric drive operation at its limit mechanical characteristic in the low-speed zone under the speed variation conditions, the phase flux linkage average value can be considered almost unchanged. However, control of the average torque carried out by changing the current limitation level is performed at the magnetic flux weakening background. It has been determined that during operation in a high-speed zone at invariable phase switching positions with the speed growing in a natural manner (i.e., without applying control actions), there is an excessive decrease in the flux linkage average value, which leads to a dramatic drop in the phase average torque. This drop can be compensated by progressively shifting the phase engagement position in the leading direction.

Concept Design of a Novel Superconducting PTO Actuator for Wave Energy Extraction

The role of the Power Take-Off (PTO) as part of modern Wave Energy Converters is becoming more and more relevant and many efforts have been done or are ongoing to improve its performance especially in terms of force density and efficiency. Electric Linear PTOs are inherently the most efficient category, since they are really direct drives with no intermediate stages of energy conversion. Nevertheless, conventional electric machines are usually limited in force while their efficiency is better than other type of drives but still does not allow an intense energy capture in a broad band of wave periods. In this regard, superconductivity may become a very helpful alternative that allows improving both: efficiency and force density in spite of the technological difficulties that are introduced in the Wave Energy Converter. This paper, after justifying the need for better PTO performances, presents a new concept of superconducting PTO in which both, the stator and the translator work at cold temperature, performing a reciprocating displacement inside a flexible cryostat. The concept is later applied to a Cylindrical Switched Reluctance machine whose global design is also presented in the paper. This activity has been performed as one of the work packages of the EU H2020 Sea Titan Project in which also a resistive PTO with a novel configuration has been developed.

Magnetothermal Coupling Analysis of Permanent Magnet Claw Pole Machine Using Combined 3D Magnetic and Thermal Network Method

The permanent magnet claw pole machine (PMCPM) is a special kind of transverse flux machine, different from conventional electrical machines the main magnetic flux path of PMCPM is 3D. Therefore, for accurate performance analysis,the 3D finite element method (FEM) is required to calculate both the electromagnetic characteristics and thermal distribution. However, it is time consuming especially when the coupling effect needs to be considered. In this paper, a combined 3D magnetic and thermal network method is proposed to obtain the performance of PMCPM. As the developed thermal network shares the same structure as the magnetic network, the calculated core loss can be regarded as the heat source in the thermal analysis easily, in which 3D rotational core loss is calculated as the 3D network is adopted. The proposed method holds the advantages of close magnetothermal coupling and fast calculating speed.For the calculation results verification, 3D FEM is used.

An overview of thermal modelling techniques for permanent magnet machines

Permanent magnet (PM) machines have gained increasing attention from the industry because of their potential merits over conventional electrical machines. High-temperature level in electrical machines is a major factor that can adversely impact the performance and health conditions of these machines. These effects need to be minimized to make them competitive with currently operational machines in the industry. It can be done by performing a thorough thermal analysis of the prototype during the design process and proper online thermal monitoring of the machine during the operation stage. Thermal modelling is a powerful tool for achieving such goals in both cases. This paper aims to review the state-of-the-art of thermal modelling techniques and provide a detailed comparison of them in PM machines. The fundamental concepts of heat transfer and sources of heat in PM machines are first discussed. Then, different thermal modelling techniques, including thermal subdomain models (TSMs), lumped parameter thermal networks (LPTNs), finite element models (FEMs), computational fluid dynamics (CFD), reduced order models (ROMs), and hybrid thermal models (HTMs) are introduced and compared. Finally, the utilization of these models in the thermal design, control, and monitoring of PM machines is studied.

Advances in Dual-Three-Phase Permanent Magnet Synchronous Machines and Control Techniques

Multiphase electrical machines are advantageous for many industrial applications that require a high power rating, smooth torque, power/torque sharing capability, and fault-tolerant capability, compared with conventional single three-phase electrical machines. Consequently, a significant number of studies of multiphase machines has been published in recent years. This paper presents an overview of the recent advances in multiphase permanent magnet synchronous machines (PMSMs) and drive control techniques, with a focus on dual-three-phase PMSMs. It includes an extensive overview of the machine topologies, as well as their modelling methods, pulse-width-modulation techniques, field-oriented control, direct torque control, model predictive control, sensorless control, and fault-tolerant control, together with the newest control strategies for suppressing current harmonics and torque ripples, as well as carrier phase shift techniques, all with worked examples.

Experimental Validations of Hybrid Excited Linear Flux Switching Machine

Linear Flux Switching Machines (LFSMs) possess the capability to generate adhesive thrust force, thus problems associated with conventional rotatory electric machines and mechanical conversion assemblies can be eliminated. Additionally, the unique features of high force/power density, efficiency, and a robust secondary structure make LFSMs a suitable candidate for linear motion applications. However, deficiency of controllable air-gap flux, risk of PM demagnetization, and increasing cost of rare earth PM materials in case of PMLFSMs, and inherent low thrust force capability of Field Excited LFSMs compels researchers to investigate new hybrid topologies. In this paper, a novel Double-Sided Hybrid Excited LFSM (DSHELFSM) with all three excitation sources, i.e., PMs, DC, and AC windings confined to short moving primary and segmented secondary providing short flux paths is designed, investigated, and optimized. Secondly, unequal primary tooth width optimization and additional end-teeth at all four corners of the primary equip proposed design with balanced magnetic circuit and reduced end-effect and thrust force ripples. Thirdly, the measured experimental results of the manufactured proposed machine prototype are compared with corresponding simulated model results and shows good agreements, thus validating the theoretical study.

Design and Analysis of Superconducting Magnetic-Field-Modulation Electric Machine

The field modulation electric machine has been paid much attention on account of its excellent performance. A superconducting magnetic-field-modulation (SMFM) electric machine is designed in this article with the full utilization of superconducting properties, which can increase the torque density and greatly reduce the loss. Firstly, the basic model of the SMFM electric machine is shown and compared with the traditional magnetic-field-modulation electric machine (MFM). Secondly, the modulation effect of SMFM electric machine is analyzed by magnetic circuit method. Lastly, the SMFM electric machine is analyzed by the finite element method (FEM). The electromagnetic characteristics show that the SMFM electric machine owns high torque and power density with low loss and torque ripple rate, which verifies SMFM electric machine is superior to the conventional MFM electric machine.

Barriers and Challenges Going from Conventional to Cryogenic Superconducting Propulsion for Hybrid and All-Electric Aircrafts

The development of electric aircraft is becoming an important technology for achieving the goals set by the European Commission for the reduction of gases emissions by 2050 in the aeronautical transportation system. However, there is a technology gap between the current values of specific power in commercial electric machines and those required for aeronautical applications. Therefore, the search for alternative materials and non-conventional designs is mandatory. One emergent solution is using superconducting machines and systems to overcome the current limits of conventional electrical machines. This work reviews the new hybrid and all-electric aircraft tendencies, complementing it with recent research on the design and development of high specific power superconducting machines. This includes the main topologies for hybrid and all-electric aircraft, with an overview of the ongoing worldwide projects of these aircraft types, systematizing the main characteristics of their propulsion systems. It also includes the research on superconducting machines to achieve high specific power and consider the impact on the redesign of aircraft systems, the electrical, cooling, and fuel source systems.

Design and comparative analysis of three phase, four phase and six phase switched reluctance motor topologies for electrical vehicle propulsion

Switched reluctance motor (SRM) is attracting the scientific community in recent days because of its special structural benefits. Good research work has been conducted on this machine since the ages. It has evolved as an alternative to the conventional electrical machines in variable speed drives due to rugged architecture, high-speed operation, four quadrants, lack of magnet, and adaptability to harsh surroundings. This paper reviews different topologies of SRM for electric vehicle (EV) application and a comparative study of suitable machines for electric vehicle propulsion. This paper elaborates on the design methodology and the analysis of various phases of operation of SRMs. During the design procedure, the finite element method (FEM) of optimization is used to enhance motor performance. In this study, the three different phase (3, 4 6) motors are analyzed in machine design software and finite element analysis outcomes and SRM simulation approach are discussed.

Stator Optimization of Wind Power Generators With High-Temperature Superconducting Armature Windings and Permanent Magnet Rotor

Electrical machines with high-temperature superconducting (HTS) armature windings can benefit from high power density and efficiency. Furthermore, by using permanent magnets (PM) on the rotor, the cryogenic system can be significantly simplified compared with the fully superconducting (SC) machines or the machines with SC field windings. Compared with the conventional electrical machines, the performance of machines with HTS armature windings can be more sensitive to the design parameters due to the interaction between the operating current and the flux density. In this article, the influence of stator geometry on the machine with HTS armature windings and PM rotor is investigated. By considering the interaction between the operating current and the flux density, an iteration procedure for calculating the operating current of the HTS armature windings is proposed. A 10-MW surface-mounted PM wind power generator with HTS armature windings is studied by the finite element analysis. It is found that machines with different coil angle have different behaviors when changing the tooth width and the dimensions of tooth tips, which is different from conventional electrical machines. A new design and optimization method is then developed. Finally, the optimal design is identified with global optimization.

Principal analysis of hybrid power systems with HTS electrical machines

The hybrid power systems (HPS) for transport application are currently under consideration. It causes with ecological and fuel efficiency aspects. The successful solving the problems of enhancing the specific output power parameter, fuel efficiency and diminishing weight of such systems focus on a use the cryogenic cooling and cryogenic fuel as a source of on-board energy. The article is devoted to the analysis and comparison of HPS of different design. The comparison is provided for HPS with different fuel (diesel oil, kerosene, petroleum, liquid natural gas, and liquid hydrogen). The analysis of application in HPS of different types of conventional and HTS electrical machines illustrates the advantage of the latter. The prospective of application of cryogenic power electronics is considered like advanced for HPS. Besides the article provides specific parameters of the HPS with HTS generator, motor, cryogenic electronics and HTS power cable at different cooling

Increasing the required slip range of wound induction generator in wind power systems

Eddy currents losses in the rotor in high power generators do not allow operators, under high values of slip, to regulate voltage and control of reactive power flow. The paper presents a method that can accurately estimate the eddy current losses in electric machines with a less complicated procedure. The suggested method allows researchers to analyze and reduce the losses, and consequently, to improve the wind turbine induction generators efficiencies. The given approach, based on the conventional electric machine theory and the parameters supplied by the manufacturers, predicts the eddy current losses theoretically without the need of the measured material loss data or BH curve. Increasing the range of slip variation of induction motor can be achieved by using a rotor of two layers in the radial direction with different parameters. The first layer is a laminated layer of height (h), and the second is a solid (the rotor yoke). The computation of eddy current losses is useful to change the design of the machine to minimize the losses. This paper presents a detailed modeling of the effect parameters on the eddy current losses in wind turbine induction generator.

A Novel HTS Wind Generator Having Permanent Magnets Between the Rotor Pole-Tips

Superconducting direct-drive wind generators have been proposed as a possible approach for offshore wind energy application due to their inherent high torque density and small mass compared with conventional electrical machine. In this paper, a novel 10 MW high temperature superconducting (HTS) salient pole synchronous wind generator with additional permanent magnets inserted between the rotor silent pole-tips is proposed. First, the electromagnetic structure of this new topology is designed in detail and the performance improvements of this machine are investigated by finite-element analysis. These two kinds of assist effect are also clarified. Then, the proposed structure is compared with conventional HTS wind generator without assistant magnets under the same scale constraints. The comparison results show that with the accessorial magnets, the torque density can be increased by 22%. Finally, the symmetrical three-phase short-circuit fault performances of the proposed HTS machine are conducted to verify the generator reliability.

Modelling and co-simulation of a permanent magnet synchronous generator

PurposeThe purpose of this paper is to obtain an accurate methodology for modelling and analysis of the permanent magnet synchronous generator connected to power electronic components.Design/methodology/approachThis paper presents the methodology of the co-simulation of a permanent magnet synchronous generator. It combines Simulink, Maxwell and Simplorer software to demonstrate the electrical machine behaviour connected with the power electronics’ circuit. The finite element analysis performed on the designed machine exhibit a more accurate behaviour over simplified Simulink models. Results between both simulation and co-simulation are compared to measurements.FindingsThe co-simulation approach offers a more accurate depiction of the machine behaviour and its interaction with the non-linear circuits.Research limitations/implicationsThis paper focuses on the interior permanent magnet type of PMSG and its interaction with a passive rectifier (nonlinear circuit).Practical implicationsThe advanced capabilities of the co-simulation method allow to analyse more variations (geometry, materials, etc.), and its interaction with non-linear circuits, than previous simulation techniques.Originality/valueThe co-simulation as a tool for analysis and design of systems interconnected with unconventional and conventional electrical machines and prototypes, and the comparison of the obtained results with classical analysis and design methods, against measurements obtained from the prototype.

Modeling, Design Optimization, and Applications of Switched Reluctance Machines—A Review

Switched reluctance machines (SRMs) are witnessing increased interests and applications in the industry and scientific communities thanks to the advantages of rigid structures, high reliability and robustness, the absence of permanent magnets, fast dynamic response, and low manufacturing cost. SRMs have become a feasible and popular alternative to conventional electric machines, such as induction machines and permanent magnet machines, with variable speed drives in many applications. Since improving the electromagnetic and thermal performances of an SRM at the design stage is of significant value, this paper presents an in-depth literature review on the status and potential trends of the technology pertinent to the design and optimization of SRMs in the following aspects: the mathematical modeling of the electromagnetic and thermal fields in SRMs, the enhancement of the performances in terms of the torque ripple, acoustic noise, efficiency, and torque density, and the multiobjective design optimization incorporating all the above factors. Finally, the presence of SRMs and their design considerations for specific applications in electric vehicles, aircraft and aerospace systems, wind generators, high speed, and energy storage systems are extensively discussed in this paper. The existing approaches advancing the SRM technologies are systematically and comprehensively summarized and compared for each category.