Machine Losses Research Articles

Study on Rotor Eddy Current Losses in High-speed Permanent Magnet Brushless Machines for Aircraft Applications

To improve the power density of aviation electric drive system, the high-speed permanent magnet machines has more and more popular in the air compressor, radial compressor, and electro-hydrostatic actuator applications. Two methods have studied to reduce the rotor eddy current losses in high-speed permanent magnet machines in this paper. Firstly, rotor eddy current losses at different stator slot openings are investigated, the stator core loss are considered simultaneously. Secondly, to reduce the magnet eddy current loss in carbon fiber retaining sleeve, the copper shield is added between permanent and carbon fiber, and the rotor eddy current losses at different copper shield width are studied.

Iron-Loss and Magnetization Dynamics in Non-Oriented Electrical Steel: 1-D Excitations Up to High Frequencies

This paper presents a thorough introduction to and application of the Parametric Magneto-Dynamic (PMD) model of soft magnetic steel sheets. The theoretical background is reviewed, and two different ways are discussed to account for the viscosity-like effects originating from microscopic eddy currents. This is followed by the theoretical calculation of magnetization dynamics and dynamic hysteresis loops in Non-Oriented (NO) electrical steel. Both classical and viscosity-extended approaches are discussed, with respect to the ability of replicating the dynamic hysteresis loop shape and iron-loss under sinusoidal excitation waveforms up to high excitation frequencies. Comparisons against measurements are analyzed for M400-50A and M235-35A NO electrical steel over a wide range of magnetic flux density and excitation frequencies. The proven accuracy and efficiency of the PMD model make it a valuable tool for the calculation of iron losses in electrical machines and transformers, as well as for an in-depth study of magnetization dynamics in individual laminations.

Iron Loss Analysis of Permanent-Magnet Machines by Considering Hysteresis Loops Affected by Multi-Axial Stress

This article describes a method to calculate iron loss of permanent-magnet machines by considering the hysteresis loops affected by multi-axial stress. A simple hysteresis model is introduced and modified by reluctivity and hysteresis loss increase ratios, which can be determined by core material experiments under uniaxial stress. This model is coupled with time-stepping finite-element analysis. The validity of the proposed method is confirmed by the core material experiments under multi-axial stress and measured characteristics of permanent-magnet machines. It is clarified that the accuracy of the proposed method is acceptable.

Evaluating the Effects of Electric and Magnetic Loading on the Performance of Single and Double Rotor Axial Flux PM Machines

Axial-flux permanent-magnet machines are used particularly in applications requiring a compact structure. Their disc-shaped topology and axial airgap have led to a variety of configurations including two popular ones: the yokeless and segmented armature (YASA), and the single-stator single-rotor or single-sided machine. In this study, a comprehensive comparative analysis of these configurations is conducted at different magnetic and electric loadings. It is found that at lower loadings, typically employed for air-cooled machines, the torque/ampere characteristics of the YASA machine are almost identical to those of a single-sided machine constructed with half the magnet volume. On the other hand, the single-sided machine outperforms the YASA machine when the magnet volumes in both machines are maintained equal. However, for higher electric loadings, the torque/ampere characteristics of the YASA machine droop significantly less than those of the single-sided machine. This article includes analytical estimations, which are verified with experimentally validated finite element analysis (FEA) simulations. In addition, the impacts of the armature reaction on saturation and the magnetic flux linkage, the magnet losses, and eddy current losses in both machines are also explored.

Study on Magnet Eddy Current Losses in Interior Permanent Magnet Machines for Aircraft Electric Green Taxiing Systems

The magnet eddy current of multi-layered interior permanent magnet (IPM) machines is studied in the paper for the aircraft electric green taxiing systems. The armature reaction flux density distribution, eddy current density and harmonic spectrum at the end of permanent magnet are analysed. A method to reduce the magnet eddy current of multi-layered IPM machines is presented. That is to increase the distance between outer permanent magnet and rotor surface and the distance between two layers of permanent magnet so as to provide a larger core path for armature reactive flux. This method can effectively reduce the magnet eddy-current loss of the multi-layered IPM machines and improve the operation efficiency.

Method for assessing the effectiveness of the use of electromechanical transmissions of vehicles at the design stage

The vehicles equipped with electromechanical transmission due to the development of traction electric drive, as well as on-board electric energy storage became very prospective. However, at the stage of such vehicles design the difficulties associated with evaluating the energy efficiency of the developed vehicles, in particular, with the evaluation of the efficiency of traction electric vehicles arise. In this work, the authors propose a method for evaluating the efficiency of traction electric motors of newly developed electromechanical transmissions of transport vehicles, based on the construction of an empirical dependence approximating statistical data on the characteristics of existing electric motors. The data on electric motors from a number of manufacturers used in vehicle transmissions was studied for approximation. The article discusses the application of the developed method to design an algorithm for controlling the transmission of a wheeled vehicle, aimed at increasing its energy efficiency. The efficiency of the algorithm is confirmed by simulation of the dynamics of the vehicle, the initial data for the simulation were obtained during the traction-dynamic calculation. The developed simulation model together with the method of evaluating the efficiency of the electric motor made it possible to carry out a comparative assessment of the developed gearshift control algorithm and the gearshift approach, which does not take into account the dependence of the energy losses of the electric machine on the operating mode in cases of urban and mixed driving cycles. As criteria for assessing the effectiveness of the application of the developed law of control of an electromechanical transmission, the amount of energy spent on movement along a given cycle and the number of gear shifts on the route were used. The obtained results confirm the effectiveness of using the developed algorithm in the conditions of vehicle movement in an urban environment.

Postfault Operation of Five-Phase Induction Machine With Minimum Total Losses Under Single Open-Phase Fault

Five-phase induction machines (FPIM) have attracted notable interest in safety critical applications as well as wind energy generation systems. This is largely due to their additional degrees of freedom that retain the machine starting/running steadily under fault conditions. In the available literature, postfault operation of multiphase machines is typically implemented using two techniques: minimum losses (ML) or maximum torque per ampere (MT) strategies. The optimization embedded into the control strategy, however, mostly addresses minimization of the stator copper loss, while the effect of the rotor loss and core loss are discarded in the optimal current calculation. This paper revisits postfault operation of the FPIM under single open phase fault (1OPF) by including the effect of both rotor loss and core loss on the machine's optimal current calculation over the full achievable loading range. The proposed searching algorithm, which combines the advantages of both MT and ML techniques, attempts to minimize the total machine losses induced by the current components of both the fundamental $\alpha \beta $ and the secondary $xy$ subspaces. The theoretical findings have been experimentally validated using a 1.5Hp five-phase prototype system.

Сучасний стан і тенденції розвитку засобів ідентифікації бойових отруйних речовин в Україні: шляхи гармонізації у відповідності до стандартів ЄС і НАТО. Частина ІІ

ABSTRACT. Modern chemical-warfare (CW) reconnaissance tasks require a fundamentally new approach to the development of methods and technologies to create a database of technical means that provide the necessary sensitivity, responsiveness and specificity. This phase of the study involves chemical control equipment that is in operational service with EU and NATO armies. Objective: analysis of current international technological standards in the field of control of chemical warfare agents, which are in operational service with EU and NATO armies. Materials and Мethods. Domestic and foreign sources of scientific information, covering current issues of CBRN security in terms of chemical substances control equipment in EU and NATO countries and review of the prospects of their introduction into the arsenal of the Armed Forces of Ukraine. The following methods of scientific research were applied: analytical, historical, bibliographic, systematic and informational approach, expert assessments. Results and Discussion. The analysis of foreign chemical control equipment showed that the most priority are portable gas alarms, robotic and air complexes of CW reconnaissance with the possibility of remote detection of the contaminated area, their integration into automated control systems, which provide prompt collection, processing and transfer of information on changing the chemical environment. As for modern chemical control tools in EU and NATO countries in the field of detection and identification of chemical warfare agents and hazardous chemicals, chemical, physical and chemical, biochemical and spectrometric methods are the most applied due to the speed and high reliability of the results. Currently, there is a need to equip the units of the tactical branch of the Armed Forces of Ukraine and the Preventive Medicine Service of the Ministry of Defense of Ukraine with a multi-purpose warning system of radiation and chemical threats. The compatibility of the warning and troop commanding system will reduce the loss of military personnel and machines during possible combat operations using weapons of mass destruction, as the systems will increase the speed of decision making on the use of individual and collective protective equipment. Conclusion. Harmonization of the standards of the Armed Forces of Ukraine with NATO standards in the field of chemical control is a complex task that requires changes in the system of standards of medical care, which include regulatory, engineering, tactical, medical, educational, and other processes. National scientific and technical potential may be the basis for the creation of new and improved technologies for the production of CW reconnaissance devices and means to indicate chemical warfare agents (CWA) for the needs of the Armed Forces of Ukraine. Keywords: military toxicology, chemical weapon, identification of chemical warfare agents.

Nonlinear Control Operation of DFIG-Based WECS Incorporated With Machine Loss Reduction Scheme

This article presents a novel adaptive backstepping based nonlinear control scheme incorporated with machine loss reduction and parameter uncertainties for grid-connected doubly fed induction generator (DFIG) driven wind energy conversion system (WECS). The proposed nonlinear controller is developed to stabilize both the grid and rotor side current control loops of direct-drive DFIG-based WECS. Traditional feedback linearization controllers are sensitive to system parameter variations and disturbances on DFIG-based WECS, which demands advanced control techniques for stable and efficient performance considering the nonlinear system dynamics. The proposed nonlinear controller incorporates the system uncertainty and nonlinearities while ensuring the stability of the drive system through Lyapunov stability criteria. A machine loss reduction algorithm is also incorporated to achieve enhanced efficiency. The performance of the proposed nonlinear scheme is compared with conventional benchmark fixed gain proportional-integral control and sliding mode control scheme for the rotor-side converter controller. The proposed nonlinear controller for DFIG-based WECS integrated with machine loss reduction scheme is successfully implemented in real time using DSP board DS 1104 for a prototype 350 W DFIG. The simulation and experimental results prove the efficacy of the proposed scheme under variable operating conditions such as wind speed variation, grid voltage disturbances, and parameter uncertainties.

Research of acquisition and prediction method in early weak information of locomotive traction system

Many key parts of mechanical equipment gradually enter failure period with service, and failures happen in some of them, it will lead to serious consequences with economic loss and crash of machine and death of human if weak failures cannot be identified in time, which might degrade to major failure. It would be of benefit to prevent the fault deterioration if faults could be identified in early period, with the states of key parts obtained. Locomotive gear was chosen as the research object here, a method of inhibition mode mixing and characteristic frequency acquisition based on dynamic cascade empirical mode decomposition is put forward for the weakness and aliasing out of uncertain factors. The fault features are much more obviously presented in different time scale by optimal intrinsic mode function (IMF) acquisition and the improvement of envelope solution method. The results of experiment show that weak faults can be obtained under much noise, and an effective method is provided for early fault prognosis and diagnosis.

Prediction of Eddy Current Losses in Cooling Tubes of Direct Cooled Windings in Electric Machines

The direct coil cooling method is one of the existing cooling techniques for electric machines with concentrated windings, in which cooling tubes of conductive material are inserted between the windings. In such cases, eddy current losses are induced in those cooling tubes because of the time variant magnetic field. To compute the cooling tubes losses, either a transient finite element simulation (mostly based on commercial software), or a full analytical method, which is more complex to be constructed, is required. Instead, this paper proposes a simple and an accurate combined semi-analytical-finite element method to calculate the losses of electric machines having cooling tubes. The 2D magnetostatic solution of the magnetic field is obtained e.g., using the free package “FEMM”. Then, the eddy current losses in the tubes are computed using simple analytical equations. In addition, the iron core losses could be obtained. In order to validate the proposed method, two cases are investigated. In Case 1, a six-toothed stator of a switched reluctance machine (SRM), without rotor, is employed in which six cooling tubes are used while in Case 2 a complete rotating SRM is studied. The proposed method is validated by a 2D transient simulation in the commercial software “ANSYS Maxwell” and also by experimental measurements. Evidently, the proposed method is simple and fast to be constructed and it is almost free of cost.

Energy loss prediction in nonoriented materials using machine learning techniques: A novel approach

AbstractTraditional extrapolation performed by machine designers for energy loss estimation results in the decrease of the overall efficiency of electrical machines. Therefore, state‐of‐the‐art techniques need to be developed in order to accurately predict the energy loss in electrical machines for their improved performance. To this end, machine learning techniques have been employed to predict accurate energy loss at different frequencies and induction levels under rotational conditions. Such types of flux exist near the teeth of the stator in synchronous machines. In transformers, rotational flux arises at the bends and corners of the stators. It was observed that the random forest machine learning algorithm has the least mean square error and as such is the most suited algorithm, which can be used for the accurate prediction of energy loss in nonoriented materials.

Losses Minimization Control for an Integrated Multidrive Topology Devoted to Hybrid Electric Vehicles

This paper deals with the study and implementation of a losses minimization control strategy for an integrated multidrive (IMD) topology used in the drivetrain of parallel hybrid electric vehicles. In this IMD, the stator sections of a multiwinding induction machine are interfaced to the storage units through standard three-phase inverters. The goal of this study is to optimize the management of multidirectional power flows in an IMD configuration, reducing both the power losses of the induction machine and the energy storage units while keeping the computational complexity suitably low. To this aim, the proposed approach consists in a control strategy that continuously searches for the best compromise between the torque response and the power capability of each storage unit while minimizing the overall power losses. Using such an approach, a significant improvement in the overall efficiency is obtained. Simulations and experimental tests confirm the effectiveness of the proposed method.

A New Global Transposition Method of Stator Winding and Its Loss Calculation in AC Machines

The stator winding acts as a carrier for the electrical load, and its loss accounts for about 50% of the total loss in AC machines. So how to design the stator winding for reducing winding loss is extremely crucial. Some traditional transposition methods are adopted in the winding design for large AC machines. Although they have a certain effect on reducing winding loss, there is still room for the improvement in the winding design and manufacturing technology. In this paper, a new global transposition method of stator winding is proposed. Then a megawatt driving motor is taken as the research object, and the eddy current losses, circulating current losses and total losses of winding strands are calculated by the three dimensional (3-D) finite element method (FEM) which has been validated by the experiment. In addition, by comparison with the two original transposition methods, it is proved that the proposed global transposition method is more effective in further reducing the winding loss, and the winding loss distribution is more uniform. This global transposition method proposed in this paper provides a reference for the optimal deign of the stator winding in AC machines.

Reduction of Winding AC Losses by Accurate Conductor Placement in High Frequency Electrical Machines

In the design of electrical machines, the increase in power density has become one of the main research themes. With most of the power loss in high power density electrical machines often being generated in the stator winding assembly, it is necessary to reduce these losses. The effects of strands and bundle positions in the slot on the ac losses in the winding are often overlooked. Taking as a case-study an existing high-frequency machine, this article analyzes and provides an in-depth insight into such effects. Exploiting the rapid advancements in precision three-dimensional printing, it is found and experimentally verified that by controlling the position of the conductors within the top of the slot the ac losses can be markedly reduced.

Effect of Laser Cutting on Core Losses in Electrical Machines—Measurements and Modeling

Cutting of the electrical steel sheets to appropriate shape and size is performed during the manufacturing of electrical machines that leads to the magnetic material deterioration near the cutting edge. Epstein frame measurements of electrical steel samples of different widths cut by laser cutting are carried out in the range of 20–400 Hz frequency of sinusoidal excitations. Two stators one with laser cut and another one with electric discharge wire cutting are manufactured and the effect of cutting on core losses is analyzed. The effect of cutting on the magnetic permeability and core losses are modeled with analytical equations. Furthermore, the model is implemented in the finite-element (FE) simulation of the Epstein frame test setup. The presented loss model is found to reproduce the measurement results reasonably. The loss model is then applied to the simulation of a cage induction machine with time-stepping FE analysis (FEA). A significant increase in core losses was observed both in simulations and measurements due to the effect of laser cutting. The presented cutting model closely follows the measured core losses.

Current control designed with model based predictive control for six-phase motor drives

Finite control set model-based predictive control techniques are distinguished by being an interesting alternative to traditional field oriented control techniques for multiphase drives due to their fast dynamic response and flexibility in the introduction of constraints. However, those predictive control techniques have some drawbacks regulating the (x−y) current components which can cause machine losses as well as a high computational burden. This paper presents a comparative study of an enhanced predictive current control technique with a conventional predictive control technique and two hybrid predictive control techniques applied to an asymmetrical six-phase induction motor drive in terms of current tracking, total harmonic distortion of stator currents and computational burden. Experimental results are reported to demonstrate the benefits of the different current control techniques by using the mean squared error and total harmonic distortion of stator currents as quality figures of merit and the number of floating point operations to measure the computational burden of each predictive control, thus concluding the advantages and limitations of each technique at transient and steady regimes.

Energy Loss Coefficients ki in a Displacement Pump and Hydraulic Motor used in Hydrostatic Drives

Abstract The article aims at defining and analysing the energy loss coefficients in design solutions of rotating displacement machines, with a piston machine as an example. The energy losses observed in these machines include mechanical loss, volumetric loss, and pressure loss. The scale and relations between these losses in different machines depend on machine design and manufacturing quality, and on operating parameters. The operating parameters, in turn, which affect directly or indirectly the above losses depend on whether the machine works in pump or hydraulic motor regime. The article is also a contribution to the development of a library of ki coefficients which define the losses in displacement machines, as the knowledge about these coefficients makes it possible to assess fast and easily the energy efficiency of a machine or drive system at each point of its working area.

Analysis of PM Eddy Current Loss in Four-Phase Fault-Tolerant Flux-Switching Permanent-Magnet Machines by Air-Gap Magnetic Field Modulation Theory

In this article, the permanent-magnet (PM) eddy current loss in a four-phase fault-tolerant flux-switching PM (FT-FSPM) machine is investigated from the perspective of air-gap magnetic field modulation. It can be found that the PM eddy current loss in FT-FSPM machines results from the relative motion between air-gap field space harmonics and PMs. Some effective working harmonics produce the major PM eddy current loss. The proportion of PM eddy current loss generated by each working harmonic is studied in detail, revealing that the low-order (third) harmonic is the main factor. Then, two new structures are proposed to reduce PM eddy current loss, in which magnetic flux barriers are designed by reducing low-order harmonics from the aspect of magnetic field modulation theory. Electromagnetic performance is investigated by finite element analysis. The results show that the proposed structure is effective to suppress PM eddy current loss. Finally, an experimental test platform is established to verify the theoretical analysis results.

Foreword

It is my great pleasure to welcome you to the 11th International Conference on Compressors and their Systems, in City, University of London from 9th - 11th September 2019. The conference is organised in collaboration with our esteemed partners; Institution of Mechanical Engineers (IMechE), Institute of Refrigeration (IOR) and International Institute of Refrigeration (IIR) and on behalf of the Organising Committee I would like to thank them for supporting and promoting this event.