Types Of Electrical Machines Research Articles

Efficiency Analysis of Low Electric Power Drives Employing Induction and Synchronous Reluctance Motors in Pump Applications

Due to the rapid increase in the number of variable speed AC drives, the analysis of their energy efficiency has become highly essential. However, such an analysis requires consideration of a wide variety of factors. This includes considering the energy loss in the frequency converter, depending on the motor type. In this article, a computational comparison of the energy properties of variable frequency pump drive employing two types of electric machines, i.e. an induction and a synchronous reluctance motor, is presented. The effect of the motor type on the losses in a low-voltage two-stage frequency converter using analytical and numerical models, with a further comparison, is investigated. Furthermore, an alternative approach to determine the current magnitude and power factor of the load of the converter is suggested. Eventually, this study provides a quantitative estimate of the increase in losses in the converter caused by using the two different motor types. Several experimental tests are conducted on induction and synchronous 1.1 kW reluctance motors.

Development of a renewable hybrid power plant with extended utilization of pumped storage unit equipment

The scheme of a renewable hybrid power plant with the extended use of the installed equipment of the pumped storage unit for the conversion of the photovoltaic and wind generators direct current to the alternating one is proposed.The scheme is based on existing components with widely used proven technology. To output the power of solar and wind generators to the grid and for DC to AC conversion, a synchronous generator of the pumped storage unit is used in addition to grid inverters. An induction motor, powered through a variable frequency drive from a common DC bus, is used together with a hydraulic turbine to rotate the generator. In addition, batteries and capacitors banks are connected to the DC bus.The possibility of using various types of electric machines to drive a synchronous generator is analyzed and the preference of an induction motor is shown. The response of an induction motor to rotational speed fluctuations is modeled and its capability to participate in the network frequency regulation is shown. With the example of a typical daily load and generation profile, it is shown that the proposed solution for DC to AC conversion has an efficiency close to that of the grid inverter.The proposed scheme of the hybrid power plant can increase the reliability of renewable energy sources and the stability of the network frequency. This is achieved due to increasing the inertia of the rotating masses in the power system, the power factor control capabilities of the synchronous generator and the proper response of induction motor to rapid fluctuations of the rotation speed. The creation of such hybrid power plants opens the way for a further increase in the share of renewable energy sources in the power system

Reluctance Electric Machines: Design and Control [Book News

This book is an overview of various types of reluctance electrical machines and elements of their modeling, design, and control. It describes reluctance electrical machines by classification. The following types of machines are covered: reluctance synchronous machines; brushless dc multiphase reluctance machines; claw pole–synchronous motors; switched reluctance machines; Vernier permanent-magnet machine drives; flux- switched (stator permanent magnet) reluctance electric machines; flux-reversal reluctance electric machines; transverse flux-reluctance electric machines; dual stator winding (doubly fed brushless) reluctance electric machines; magnetically geared reluctance electric-machine drives; and dc plus ac doubly salient electric machines. The authors describe the construction of these machines and include mathematical models. They also compare electrical machines, underscoring their advantages and disadvantages. The book lists, in addition to the operational features, the costs of machine elements and how those elements affect machine construction. Also, modern control strategies, including motion sensorless operation, are thoroughly discussed. The inclusion of many examples and simulations makes this otherwise difficult material easy to understand. The book is very useful for students of electrical, mechanical, and mechatronics as well as for practicing engineers interested in the design and optimization of electrical machines and drive systems.

Guest Editorial Emerging Electric Machines and Drives for Smart Energy Conversion

Energy conversion is one of the key steps for human utilizing the energy. In particular, as the key component for electromechanical energy conversion, electric machines play a significant role and greatly promote the development of modern civilization. Actually, the conventional types of electric machines, namely DC machines, induction machines, and synchronous machines, as well as surface permanent-magnet (SPM) machines and inserted-PM (IPM) machines, have been widely applied for various aspects in human lives. In recent years, emerging electric machines, including the double-salient type, hybrid-excitation type, PM memory type, magnetic-gearing type, PM vernier type, advanced magnetless type, multiport type, and some newly developing types, are proposed for new application occasions such as electric vehicles (EVs), electric ships, electric aircraft, electric robotics, wind power generation, unmanned propulsion systems, and so on. In addition, the corresponding advanced control strategies have presented for electric drives, which include the direct torque control (DTC), field oriented control (FOC), finite control set model predictive control (FCS-MPC), fault-tolerant control, and sensorless control. Thus, emerging electric machines and drives take active roles for applications with more electric or full electric. This special section brings new findings of electric machines and drives on their topologies, structures, analysis approaches, advanced control strategies, and new applications.

Automation and control of blow moulding mechanisms according to the criterion of maximum energy efficiency

The article presents the control algorithms that allow to increase the energy efficiency of the metallurgical production facilities’ blow molding mechanisms by impacting on the actuating elements of electrical engineering complexes. A mathematical model is proposed that allows the calculation of energy efficiency. It is shown that this effect is achieved due to: a systematic approach to the design of electrical systems; the use of new types of electric machines; selection of control and regulation algorithms; transition of unregulated control systems to adjustable electric drives; rational choice of elements of electrical systems; increasing the level of staff skills. Energy efficiency assessment was performed for the object, which proposed the mutual influence of the elements of the system. The proposed control laws were compared with systems based on unregulated electric drives and structures in which the air flow was controlled by the guide vanes. It has been established that while transitioning to new control algorithms, it is possible to reduce losses in the system by about 35%.

Comparison of Performance and Controlling Schemes of Synchronous and Induction Machines Used in Flywheel Energy Storage Systems

For stable operation of the electrical grid, it is vital to maintain a balance between demand and supply of electrical power. Imbalance at any instant between consumption and generation causes voltage and frequency instability. Intermittent generation (wind and solar) in power systems is more likely to cause such imbalances hence the existence of frequency and voltage variations. To address stability issues due to integration of intermittent renewable sources into the grid, a storage device is required which can quickly respond to the power fluctuations. A Flywheel Energy Storage System (FESS) has the capability to respond within a sub-second timescale and is able to address the problems caused by power variations. The performance of FESS is highly dependent on the type of motor/generator (MG) set which is the key component generating or absorbing power from grid. The three main types of electrical machines used in FESS applications are synchronous machine (SM), induction machine (IM) and the switched reluctance machine (SRM). SRM is less commonly used due to high current ripples and complex torque control [1]. SM is used for high speed applications due to its high efficiency and IM is used for high power applications due to its rough construction. This research focuses on the comparison of synchronous and induction machines used in flywheel energy storage systems for microgrid applications [2]. The operation and controlling schemes of each electrical machine has been described as used in the analysis made in the MATLAB/Simulink environment.

Brushless Nonsteel HTS Generator With Combined Excitation With Trapped Field Plates on the Rotor

Presently, the high-speed electric machines with increased specific power are in the mainstream of research and are being developed worldwide. The high-temperature superconductor (HTS) machines allow improving the specific power even more significantly. The inductor generators are one of the perspective types of such machines. A new type of high-speed HTS electric machines is proposed in this paper. The proposed machine combines properties of generator with permanent magnets and inductor generator. In the rotor of this machine, permanent magnets are replaced by the stacks of HTS plates. In this case the HTS generator can be operated as an inductor iron-free HTS generator with combined excitation. This paper is devoted to the experiments and simulation of the proposed HTS generator. The experiment and simulation results prove the implementation of such design at three regimes: inductor, trapped-field, and combined excitation. The future development of the proposed HTS generators and perspectives of their application is discussed.

New Subdomain Technique for Electromagnetic Performances Calculation in Radial-Flux Electrical Machines Considering Finite Soft-Magnetic Material Permeability

The most significant assumption in the subdomain technique (i.e., based on the formal resolution of Maxwell’s equations applied in subdomain) is that the iron parts are considered to be infinitely permeable, so that the saturation effect is neglected. In this paper, we present a novel contribution on improving this 2-D technique in polar coordinates by focusing on the consideration of iron relative permeability. In non-periodic regions, magnetostatic Maxwell’s equations are solved considering non-homogeneous Neumann boundary conditions, and the general solution is obtained by applying the interfaces conditions in both directions (i.e., $r$ - and $\theta $ -edges ICs). The proposed model is relevant for different types of radial-flux electrical machines with(out) permanent magnets (PMs) supplied by a direct or alternate current (with any waveforms). For example, the semi-analytical model has been implemented for spoke-type PM machines. The magnetic field calculations have been performed for two different values of iron core relative permeability (viz, 100 and 600), and compared with those obtained by the 2-D finite-element method. The semi-analytical results are in a very good agreement with those obtained numerically, considering both amplitude and waveform.

Development of a High-Fidelity Model for an Electrically Driven Energy Storage Flywheel Suitable for Small Scale Residential Applications

Energy storage systems (ESS) are key elements that can be used to improve electrical system efficiency by contributing to balance of supply and demand. They provide a means for enhancing the power quality and stability of electrical systems. They can enhance electrical system flexibility by mitigating supply intermittency, which has recently become problematic, due to the increased penetration of renewable generation. Flywheel energy storage systems (FESS) are a technology in which there is gathering interest due to a number of advantages offered over other storage solutions. These technical qualities attributed to flywheels include high power density, low environmental impact, long operational life, high round-trip efficiency and high cycle life. Furthermore, when configured in banks, they can store MJ levels of energy without any upper limit. Flywheels configured for grid connected operation are systems comprising of a mechanical part, the flywheel rotor, bearings and casings, and the electric drive part, inclusive of motor-generator (MG) and power electronics. This contribution focusses on the modelling and simulation of a high inertia FESS for energy storage applications which has the potential for use in the residential sector in more challenging situations, a subject area in which there are few publications. The type of electrical machine employed is a permanent magnet synchronous motor (PMSM) and this, along with the power electronics drive, is simulated in the MATLAB/Simulink environment. A brief description of the flywheel structure and applications are given as a means of providing context for the electrical modelling and simulation reported. The simulated results show that the system run-down losses are 5% per hour, with overall roundtrip efficiency of 88%. The flywheel speed and energy storage pattern comply with the torque variations, whilst the DC-bus voltage remains constant and stable within ±3% of the rated voltage, regardless of load fluctuations.

Analysis and Performance Evaluation of Axial Flux Permanent Magnet Motors

For special types of electric machines, it is essential and of utmost interest to develop a mathematical model, characterize a machine for performance evaluation, and test the machine for study and applications. A 2-D analytical method for the performance evaluation of axial flux permanent magnet (AFPM) machine has been presented in this paper. The method computes the electromagnetic torque, magnetic field distribution, cogging torque, and back-electromotive force of the machine using quasi-3-D modeling. Fourier Transform is used for the solution of Maxwell's equations in different regions of the AFPM machine. A surface mounted AFPM motor is designed and developed and tested. Experimental results are demonstrated and compared with the results computed from the analytical model to validate the effectiveness and accuracy of the proposed method.

Viscoelastic property tuning for reducing noise radiated by switched-reluctance machines

Switched-reluctance motors (SRM) present major acoustic drawbacks that hinder their use for electric vehicles in spite of widely-acknowledged robustness and low manufacturing costs. Unlike other types of electric machines, a SRM stator is completely encapsulated/potted with a viscoelastic resin. By taking advantage of the high damping capacity that a viscoelastic material has in certain temperature and frequency ranges, this article proposes a tuning methodology for reducing the noise emitted by a SRM in operation. After introducing the aspects the tuning process will focus on, the article details a concrete application consisting in computing representative electromagnetic excitations and then the structural response of the stator including equivalent radiated power levels. An optimised viscoelastic material is determined, with which the peak radiated levels are reduced up to 10 dB in comparison to the initial state. This methodology is implementable for concrete industrial applications as it only relies on common commercial finite-element solvers.

Guest Editorial

Guest Editorial

Algorithms for Determining the Parameters of Static Converters

Qualitative needs, ever higher, automatic control systems, correlated with the development of power electronics, microprocessors, programming techniques, development of unconventional energy production, resulting in bringing to the fore the three-phase power converters. Using asynchronous motor, the simplest and robust electric car, often can not meet the quality conditions of the machine working. AC machines can not achieve a wide range of speeds and a hub can not cover 250-300% overload.Widespread use in electric drive systems that we obtained semiconductor electronic control methods with techniques for high efficiency and precision control very good. Static converters have become easy to use and virtually through them obtain any desired mechanical characteristic for any type of electric machine.

Flux Switching Permanent Magnet Motor using Segmented Outer Rotor Structure for Electric Scooter

Flux switching motor is a type of electric machine that locates both flux source and armature windings on the stator leaving its rotor a simple piece of iron. This machine was developed by combining the toothed stator structure of induction machine and the toothed rotor structure of switched reluctance machine together. Furthermore, it has three types of flux sources which include permanent magnet. Conventionally, the toothed kind of rotor has dominated machines rotor design and has been known for high manufacturing cost and iron loss, resulting to low performance. This calls for worry and the need to overcome it and also reduce the manufacturing cost while securing high torque. This paper presents flux switching permanent magnet motor employing segmented outer rotor for high torque capability. 2D-FEA using JMAG to investigate the motor characteristics in terms of flux linkage, Induce back-emf, cogging torque, maximum average torque and efficiency. Finally, preliminary results and comparison revealed that motors employing segmented rotor are capable of higher torque than conventional toothed rotor.

A Review of Flywheel Energy Storage System Technologies and Their Applications

Energy storage systems (ESS) provide a means for improving the efficiency of electrical systems when there are imbalances between supply and demand. Additionally, they are a key element for improving the stability and quality of electrical networks. They add flexibility into the electrical system by mitigating the supply intermittency, recently made worse by an increased penetration of renewable generation. One energy storage technology now arousing great interest is the flywheel energy storage systems (FESS), since this technology can offer many advantages as an energy storage solution over the alternatives. Flywheels have attributes of a high cycle life, long operational life, high round-trip efficiency, high power density, low environmental impact, and can store megajoule (MJ) levels of energy with no upper limit when configured in banks. This paper presents a critical review of FESS in regards to its main components and applications, an approach not captured in earlier reviews. Additionally, earlier reviews do not include the most recent literature in this fast-moving field. A description of the flywheel structure and its main components is provided, and different types of electric machines, power electronics converter topologies, and bearing systems for use in flywheel storage systems are discussed. The main applications of FESS are explained and commercially available flywheel prototypes for each application are described. The paper concludes with recommendations for future research.

Quantitative comparison of electromagnetic performance of electrical machines for HEVs/EVs

In this paper, various types of sinusoidal-fed electrical machines, i.e. induction machines (IMs), permanent magnet (PM) machines, synchronous reluctance machines, variable flux machines, wound field machines, are comprehensively reviewed in terms of basic features, merits and demerits, and compared for HEV/EV traction applications. Their latest developments are highlighted while their electromagnetic performance are quantitatively compared based on the same specification as the Prius 2010 interior PM (IPM) machine, including the torque/power-speed characteristics, power factor, efficiency map, and drive cycle based overall efficiency. It is found that PM-assisted synchronous reluctance machines are the most promising alternatives to IPM machines with lower cost and potentially higher overall efficiency. Although IMs are cheaper and have better overload capability, they exhibit lower efficiency and power factor. Other electrical machines, such as synchronous reluctance machines, wound field machines, as well as many other newly developed machines, are currently less attractive due to lower torque density and efficiency.

Анализ преимуществ реактивных электрических машин при построении гребной электрической установки

The work considers various types of ship propulsion systems, their main advantages and disadvantages are given below. The advantages of an electric propulsion system based on an electric motor are described in this work. Various types of electric machines used in the construction of ship electrical propulsion systems are also considered. The choice of the reactive electric machine in ship propulsion systems was made. Various types of reactive electric machines and prospects of their use in the electric drive are considered; possible ways of their optimization (energy indicators, mass-dimensional characteristics) are shown. A comparative analysis of the reactive electric machines designs and their competitive advantages between themselves and the classic electric machines used in the electric drive is performed. Machines with different winding designs are considered, the longitudinal and transverse inductance ratios of the various types of motors are shown, which are the criterion for assessing the structure quality. The machines with a gear stator and a rotor are described in detail, the possibility of their optimization is proved by the criterion of a minimum of pulsations of the electromagnetic moment. A description is given for a synchronous reluctance machine with anisotropic magnetic conductivity of a rotor with longitudinal and transverse blending. The analysis of the energy characteristics and mass-dimensional parameters of reactive electric machines was made.

Применение генератора двойного питания для ветроэнергетических установок малой, средней и большой мощности

The paper considers the relevance of the use of renewable energy sources (RES) in the modern world energy economy, comparative statistics are provided on the share of various energy sources in electricity generation. A particular attention is paid to the use of wind energy as a source for generating electricity, namely, the statistics on the volume and dynamics of the installed capacity of wind power plants (WED) in the world, as well as statistics on the volume and dynamics of the growth of generated electricity with the help of wind turbines in the world. The factors that contributed to the development of the wind power industry in the countries with the greatest share of the use of wind turbines in the world were analyzed. The design of existing types of wind turbines is described. The main technological problem of wind power engineering is formulated and the way to solve this problem is determined. Different types of generators for wind turbines are considered and advantages and disadvantages of using all the types of electric machines as generating devices in wind turbines are analyzed. The vector of development of the wind turbine in the part of the choice of the generator type is determined. The distinctive features and advantages of using a dual-power machine for windmills in comparison with other types of electric machines are shown. The information on the dual-power generators existing in the world and domestic industry is provided. A fundamentally new, detailed design of a dual-power machine with a non-contact exciter installed on a single shaft is presented, and the main advantages of this technical solution regarding the traditional design of a double-feed machine that includes a sliding contact are described.

Development of Correlations for Windage Power Losses Modeling in an Axial Flux Permanent Magnet Synchronous Machine with Geometrical Features of the Magnets

In this paper, a set of correlations for the windage power losses in a 4 kW axial flux permanent magnet synchronous machine (AFPMSM) is presented. In order to have an efficient machine, it is necessary to optimize the total electromagnetic and mechanical losses. Therefore, fast equations are needed to estimate the windage power losses of the machine. The geometry consists of an open rotor–stator with sixteen magnets at the periphery of the rotor with an annular opening in the entire disk. Air can flow in a channel being formed between the magnets and in a small gap region between the magnets and the stator surface. To construct the correlations, computational fluid dynamics (CFD) simulations through the frozen rotor (FR) method are performed at the practical ranges of the geometrical parameters, namely the gap size distance, the rotational speed of the rotor, the magnet thickness and the magnet angle. Thereafter, two categories of formulations are defined to make the windage losses dimensionless based on whether the losses are mainly due to the viscous forces or the pressure forces. At the end, the correlations can be achieved via curve fittings from the numerical data. The results reveal that the pressure forces are responsible for the windage losses for the side surfaces in the air-channel, whereas for the surfaces facing the stator surface in the gap, the viscous forces mainly contribute to the windage losses. Additionally, the results of the parametric study demonstrate that the overall windage losses in the machine escalate with an increase in either the rotational Reynolds number or the magnet thickness ratio. By contrast, the windage losses decrease once the magnet angle ratio enlarges. Moreover, it can be concluded that the proposed correlations are very useful tools in the design and optimizations of this type of electrical machine.

Fully predictive heat transfer coefficient modeling of an axial flux permanent magnet synchronous machine with geometrical parameters of the magnets

This paper describes new correlations for the convective heat transfer assessment in an axial flux permanent magnet synchronous machine. The case-study here is composed of an open rotor-stator with sixteen magnets at the periphery of the rotor with an annular opening in the entire disk. Air can flow in a channel being formed between the magnets and in a small gap region between the magnets and the stator surface. The idea is to use the space in between adjacent rotor magnets as cooling air-channels. The rotor disk with the magnets then behaves as a centrifugal fan causing efficient air gap cooling. In order to construct the correlations, CFD simulations are performed at the practical ranges of important non-dimensional parameters including the gap size ratio (G=s/R), the rotational Reynolds number (Re=ωR2/ν), the magnet angle ratio (αm=α×16/360) and the magnet thickness ratio (L=t/R). Considering the geometric periodicity of the computational domain, only one magnet on the rotor disk is investigated. Moreover, the Frozen Rotor method is used to simulate the rotary motion of the rotor together with the fluid around it. Unlike most precedent studies that considered ambient temperature as the reference temperature, therefore making the estimated convective heat coefficient dependent on the surface temperature, a different approach has been taken into account here. The reference temperature is computed through a minimization method in such a way that the mean Nusselt number becomes rather independent of the surface temperatures. It is found that the proposed correlations can strongly predict the heat transfer rates for all surfaces within the machine at the practical ranges of the magnet geometrical parameters and other significant factors. A more clear insight about the heat transfer in the rotor-stator system in this type of electrical machine is presented. It is shown that the overall heat transfer improves significantly with an increase in the magnet thickness ratio, whereas the opposite trend is observed as the magnet angle ratio goes up. Moreover, the results reveal that the stator heat transfer in the gap reaches a maximum for a certain gap thickness.