Machine Losses Research Articles

A Computationally Efficient Semi-Analytical Method for Circulating Current Loss of High Speed Permanent Magnet Machines

A Computationally Efficient Semi-Analytical Method for Circulating Current Loss of High Speed Permanent Magnet Machines

Simple and Accurate Computation of Rotor Eddy-Current Losses in Surface-Mounted Permanent Magnet Machines Accounting for Magnet Circumferential Segmentation

Simple and Accurate Computation of Rotor Eddy-Current Losses in Surface-Mounted Permanent Magnet Machines Accounting for Magnet Circumferential Segmentation

Optimal drive cycle current supply of a wound field automotive electrical machine using surrogate models

Surrogate models have become a widely used solution for reducing computation times along design processes. In this work, a Gaussian Process surrogate model is built and used to predict the performance and losses of a wound field electrical machine in a fast manner. This approach is relevant, especially for drive cycle calculations that rapidly generate rising computation costs if they are computed using physical models, especially finite elements analysis. We present in detail the established method and a comparison of the obtained results with finite elements results. In addition, a detailed analysis of the optimized current supply is presented, and the advantages of variable excitation current are highlighted.

Analysis of Proximity Loss of Electrical Machines Using Mesh-Based Magnetic Equivalent Circuit

Analysis of Proximity Loss of Electrical Machines Using Mesh-Based Magnetic Equivalent Circuit

Calculation of Losses in a Motor Fed by a Conventional Inverter and a Battery Distributed Inverter

In the past decade, car manufacturers have started electrifying the traction chain of their vehicles. Although these vehicles attract more and more drivers, most of them have a limited range and are prohibitively expensive. Manufacturers must therefore offer high-performance conversion chains (particularly in terms of efficiency) while controlling costs. The power converter is a particularly crucial element of the conversion chains: it supplies the traction motor, and its structure and the way it is controlled can greatly influence the overall efficiency of the drive train. This paper studies two conversion structures that can be used as vehicle power converters, which are modeled and associated with an electric machine. The first is a classical three-phase inverter, and the second is a breakthrough architecture called IBIS (Intelligent Battery Integrated System). This battery integrates the conversion function directly into the battery, which reduces material costs. Two loss phenomena are also studied and modeled (with the help of finite element methods): iron losses in the electrical machine (magnetic losses in the ferromagnetic material used) and copper losses in the conductors (AC and DC losses in the conductors). The impact of the architecture is evaluated on a set of operating points from a road cycle standardized by the WLTP procedure.

Stator Core Loss Analysis and Suppression of Permanent Magnet Vernier Machines

Permanent magnet vernier machine is a new type of permanent magnet machine, which is operated based on flux modulation effect. In this paper, the stator core loss of the permanent magnet vernier machine is investigated based on the relationship of the stator core loss to harmonic components of the airgap magnetic flux density crossing airgap and leakage flux not crossing airgap. In this manner, the stator core loss can be analyzed with consideration of flux modulation effect and flux modulation pole structure. First, stator core losses generated by magnetic fields of permanent magnet and armature winding are analyzed. Then, stator tooth fluxes coming from airgap magnetic flux and leakage flux are derived. Also, non-working stator tooth flux contributing stator core loss but not contributing torque is identified. Based on this, two approaches to suppress the stator core loss of the permanent magnet vernier machine are proposed. Finally, the effectiveness of the stator core loss analysis and suppression is verified by finite element analysis and experiments.

Importance of surface roughness on the magnetic properties of additively manufactured FeSi thin walls

Thin-walled structures are being used in soft magnetic components manufactured by additive manufacturing to limit eddy current losses in AC machines. Fe-6.5wt %Si has been shown to be a promising material in such components, however most characterisation has taken place using thicker bulk material. Thermal conditions and microstructure have been shown to differ within thin-walled structures, hence magnetic properties may also differ. This study characterises the magnetic properties of thin-walled structures, showing that the 〈001〉 texture usually apparent in laser powder-bed fusion does not persist in thin-walled samples built at an angle to the build platform. Surface roughness (Sa) is shown to increase with build angle from 28 µm when perpendicular to the build platform, to 80 µm when parallel, causing a deterioration in magnetic properties such as susceptibility which is reduced by up to 25 %. Improvements in magnetic properties are demonstrated for samples with lower surface roughness due to improved laser parameters, with even larger improvements available when using polishing as a post-process finishing operation which was shown to improve susceptibility by over 10 %. This study enables the designers of soft magnetic components made by additive manufacturing, the freedom to design magnetic flux paths at any angle in the build chamber and gives surface roughness as a key parameter to improve magnetic properties.

Impact of scaling laws of permanent magnet synchronous machines on the accuracy of energy consumption computation of electric vehicles

This paper compares the impact of two scaling methods of electric machines on the energy consumption of electric vehicles. The first one is the linear losses-to-power scaling method of efficiency maps, which is widely used in powertrain design studies. While the second is the geometric scaling method. Linear scaling assumes that the losses of a reference machine are linearly scaled according to the new desired power rating. This assumption is questionable and yet its impact on the energy consumption of electric vehicles remains unknown. Geometric scaling enables rapid and accurate recalculation of the parameters of the scaled machines based on scaling laws validated by finite element analysis. For this comparison, a reference machine design of 80 kW is downscaled with a power scaling factor of 0.58 and upscaled considering a power scaling of 1.96. For comparative purposes, optimal combinations of geometric scaling factors are determined. The scaled machines are derived to fit the driving requirements of two electric vehicles, namely a light-duty vehicle and a medium-duty truck. The comparison is performed for 9 standardized driving cycles. The results show that the maximal relative difference between linear and geometric scaling in terms of energy consumption is 3.5% for the case of the light-duty vehicle, compared with 1.2% for the case of the truck. The findings of this work provide evidence that linear scaling can continue to be used in system-level design studies with a relatively low impact on energy consumption. This is of high interest considering the simplicity of linear scaling and its potential for time-saving in the early development phases of electric vehicles.

A Novel Sleeve Design to Reduce the Eddy Current Loss of High-Speed Electrical Machines

Demand for high-speed motors is increasing. Surface-mounted permanent magnet synchronous motors (SPMSM) used in high-speed applications have magnets attached to the rotor, so there is a risk of damage and scattering due to centrifugal force as the speed increases. For this reason, applying the retaining sleeve to the rotor is essential. However, when using sleeves, there is a problem of reducing efficiency due to eddy current loss. In this paper, a study was conducted on a motor for a 100 kW building air conditioning system operating at a speed of 20,000 rpm. The purpose of the study is to reduce eddy current loss by optimizing the sleeve geometry. To this end, 3D finite element analysis (FEA) using JMAG 22.1 was conducted to analyze eddy current loss, the minimum safety factor was analyzed through mechanical stiffness analysis using ANSYS Workbench, and the validity of sleeve shape was proved through cause analysis. Through the research results, it is expected that the shape change of the sleeve will have the effect of reducing eddy current loss.

Magneto-Thermal Coupling Analysis of an Axially Split Phase Spherical Bearingless Flywheel Machine

The axially-split phase spherical bearingless flywheel machine (ASP-SBFM) operates mostly in fast charging and discharging conditions. The unique topology design and high power density of the ASP-SBFM can lead to complex machine losses and result in high-temperature rise. This article employs magneto-thermal coupling to perform an accurate analysis of the temperature field distribution of the ASP-SBFM. First, as the heat source for machine temperature rise, the ASP-SBFM losses are analyzed in detail. And the theoretical calculation results agree well with the FEA results. Then, the magneto-thermal coupling method is conducted to obtain the accurate temperature distribution of ASP-SBFM, where both natural cooling and high vacuum conditions are considered. The temperature distribution results can provide a reference for machine heat dissipation design, topology optimization, and machine body material selection.

Real-time temperature prediction of electric machines using machine learning with physically informed features

Accurate estimation of the internal temperatures of electric machines is critical to increasing their power density and reliability since key temperatures, such as magnet temperature, are often difficult to measure. This work presents a new machine learning based modelling approach, incorporating novel physically informed feature engineering, which achieves best-in-class accuracy and reduced training time. The different features introduced are proportional to sources of machine losses and require no prior knowledge of the machine, hence the models are completely data driven. Evaluation using a standard experimental dataset shows that modelling errors can be reduced by up to 82.5%, resulting in the lowest mean squared error recorded in the literature of 2.40 K2. Additionally, models can be trained with less training data and have lower sensitivity to data quality. Specifically, it was possible to train a loss enhanced multilayer perceptron model to a mean squared error <5 K2 with 90 h of training data, and an enhanced ordinary least squares model with just 60 h to the same criteria. The inference time of the model can be 1–2 orders of magnitude faster than competing models and requires no time to optimise hyperparameters, compared to weeks or months for other state-of-the-art prediction methods. These results are highly important for enabling low-cost real-time temperature monitoring of electric machines to improve operational efficiency, safety, reliability, and power density.

Design Methodology of a Multifunctional Screw-Type Energy Converter

This paper examines the method of designing a non-standard electric machine – a three-phase induction motor with a hollow solid rotor, on the surface of which the turns of the screw are located. Such an unusual design makes it possible to turn the main disadvantage of induction machines with a solid rotor, namely the heating of the rotor due to the effect of eddy currents, into an advantage. The heat from the rotor is transferred to the bulk material, which is mixed by the screw, for drying and reducing the moisture content. At the same time, only one device is used to perform three functions - mixing, drying, transportation of bulk material, which, due to the specified functional features, was called a multifunctional energy converter (MEC). The MFEC design method differs from conventional machines, because it takes into account the peculiarities of determining the parameters of a number of typical methods: an induction motor with a squirrel-cage rotor, an induction motor with a solid internal rotor, and an inductor. In the previous publications of the authors, the complex methodology of designing an induction motor with an external solid rotor was considered in detail, however, in view of the additional theoretical and experimental studies conducted, it needs to be clarified and adjusted. In addition, in this paper, the beginning of the design, the determination of the initial data and the main dimensions of the MFEC is performed in a different way. In particular, the overall dimensions of the MFEC are determined not by the sum of power spent on heating and mixing the material and internal losses in an induction machine (considering the efficiency and power factor), but by the required performance of the unit and the limit dimensions of the installation area. The paper proposes a new approach to determining the dimensions of the stator slot, considering the necessary area for the placement of conductors and the current density in the winding. This paper is one of several publications that aim to reveal the features of design and mathematical modeling of such an atypical class of electric machines as an induction motor with an external hollow solid rotor.

Carbon Nanotubes as an Alternative to Copper Wires in Electrical Machines: A Review

The surge in electric vehicles (EVs) and their electrical appliances requires highly efficient, lightweight electrical machines with better performance. However, conventional wire used for electrical machine windings have certain limits to the current requirements. Copper is a commonly used material in electrical windings, and due to its ohmic resistance, it causes 75% of total losses in electrical machines (copper losses). The high mass of the copper results in a bulky system size, and the winding temperature of copper is always maintained at less than 150 °C to preserve the thermal insulation of the electric machine of the windings. On the other hand, carbon nanotubes and carbon nanotube materials have superior electrical conductivity properties and mechanical properties. Carbon nanotubes ensure 100 MS/m of electrical conductivity, which is higher than the copper electrical conductivity of 59.6 MS/m. In the literature, various carbon nanotubes have been studied based on electrical conductivity, temperature co-efficient with resistivity, material thickness and strength, insulation, and efficiency of the materials. Here, we review the electrical and mechanical properties of carbon nanotubes, and carbon nanotube composite materials are reviewed with copper windings for electrical wires.

Time-variant magnetic field, voltage, and loss of no-insulation (NI) HTS magnet induced by dynamic resistance generation from external AC fields

High-temperature superconducting (HTS) coils serving as DC magnets can be operated under non-negligible AC fields, like in synchronous machines of maglev trains and wind turbines. In these conditions, dynamic resistance is generated in HTS tapes, causing redistribution/bypassing of the transport current inside the no-insulation (NI) coil and its unique operational features. This issue was studied by experiments on an NI coil with DC current supply put into external AC fields. Due to the current redistribution induced by dynamic resistance, the central magnetic field and voltage of the NI magnet initially undergo various transient processes, and eventually exhibit a stable central magnetic field reduction and a DC voltage. These time evolutions have implications for the time-varying torque and loss of an HTS machine. These time evolutions are strongly affected by the contact resistivity distribution, and whether it is the first time that the NI magnet has been exposed to the AC field, showing several qualitatively different waveforms (e.g. some are even non-monotonic with time). The magnitudes of the stable central field reductions, and their observed linear correlation with the DC voltages are found to be decided by the local contact resistivity of the innermost and outermost several turns. It is also noted that the non-insulated turn-to-turn contact help lessening the loss induced by the dynamic resistance. A numerical model is established to analyze/explain these experimental results by observing the microscopic current distribution. Two risks of quench are noticed: (i) the azimuthal current of the middle part turns increases as the AC field is applied; (ii) a concentration of radial current is observed near the terminals of the NI coil.

Identifikasi Penyebab Kehilangan Crude Palm Oil (CPO) di Pabrik Kelapa Sawit

PT. Y is a company engaged in the processing of fresh palm fruit bunches into Crude Palm Oil (CPO), and has a production capacity of 30 tonnes/hour. The CPO production system generally goes through a long process and there are several processes that are not optimal. One of the processes is pressing, where this process experiences a lot of oil loss. Oil loss experienced at PT. Y of 6.28 to 6.32 percent of total production. Therefore, it is important to identify the causes of oil loss in the pressing process so that it becomes a preventive measure and can reduce the percentage of oil loss during the production process. The purpose of this research is to identify the factors that cause CPO oil loss and to recommend solutions to minimize CPO oil loss in screw press machines using fishbone diagrams. A fishbone diagram is used to identify the root causes of problems in a process. The cause of the problem is often caused by five elements, namely Man, Method, Machine, Material, and Environment. Fishbone diagram is useful for finding the factors that cause a problem. The results obtained from the fishbone diagram are several factors that cause oil loss in the pressing process or in the screw press machine including machine factors, raw materials, humans, and method factors. Recommendations that can be implemented by companies include routine maintenance of screw press machines, both corrective maintenance and preventive maintenance, it is necessary to control the quality of fresh fruit bunches from the beginning of harvest until the fruit reaches the loading ramp station, and this requires training so that operators can better understand how to machine operation.

Performance of Combine Harvesters for Sorghum (Sorghum bicolor (L.) Moench) in the Mechanized Rain Fed Schemes of Eastern Sudan

Direct combine harvesting of crops helps in solving the problem oflabor shortage during harvest period, timely harvest and obtaining good grainquality. A study was conducted in the mechanized rain fed schemes inGedarif State eastern Sudan to evaluate the performance of different combineharvester makes, to quantify harvesting losses and to estimate the value of thelosses for direct harvesting of sorghum. Three combine harvester makes wereassessed, namely; New Holland, Claas and Massey Ferguson. The data wascollected from 46 combine harvesters during three harvesting seasons (2014,2015and 2016). The exact number of each combine harvester make was 21, 9and 16 for New Holland, Claas and Massey Ferguson, respectively. Thecollected data included machine parameters, harvesting losses and economicdata. Results showed that the average forward speed, work rate, fieldefficiency and fuel consumption, was 5.1 km/hr, 2.2 ha/hr, 86% and 7.4 l/ha,respectively. The three harvesters produced similar seed quality in terms ofsound seeds, cracked seeds and impurities. The pre-harvest loss wassignificantly (P ≤ 0.01) the highest among the other loss types. Irrespective toharvester make, the header loss was significantly (P ≤ 0.01) the highestamong machine loss types. No significant differences were noted betweencombine harvester makes in threshing and machine losses. The totalharvesting, machine and collectable losses were 25.1 %, 10% and 19.4 %,respectively. The average value of the pre-harvest loss, machine loss, totalloss and collectable loss was 432.4 SDG/ha, 304.4 SDG/ha, 736.8 SDG/haand 188.9 SDG/ha, respectively. In conclusion, the performance of the threecombine harvesters was technically satisfactory, the machine loss was

Many-Objective Job-Shop Scheduling: A Multiple Populations for Multiple Objectives-Based Genetic Algorithm Approach.

The job-shop scheduling problem (JSSP) is a challenging scheduling and optimization problem in the industry and engineering, which relates to the work efficiency and operational costs of factories. The completion time of all jobs is the most commonly considered optimization objective in the existing work. However, factories focus on both time and cost objectives, including completion time, total tardiness, advance time, production cost, and machine loss. Therefore, this article first time proposes a many-objective JSSP that considers all these five objectives to make the model more practical to reflect the various demands of factories. To optimize these five objectives simultaneously, a novel multiple populations for multiple objectives (MPMO) framework-based genetic algorithm (GA) approach, called MPMOGA, is proposed. First, MPMOGA employs five populations to optimize the five objectives, respectively. Second, to avoid each population only focusing on its corresponding single objective, an archive sharing technique (AST) is proposed to store the elite solutions collected from the five populations so that the populations can obtain optimization information about the other objectives from the archive. This way, MPMOGA can approximate different parts of the entire Pareto front (PF). Third, an archive update strategy (AUS) is proposed to further improve the quality of the solutions in the archive. The test instances in the widely used test sets are adopted to evaluate the performance of MPMOGA. The experimental results show that MPMOGA outperforms the compared state-of-the-art algorithms on most of the test instances.

Double-Side Voltage-Behind-Reactance Model of Main Machine in Aircraft Wound-Rotor Synchronous Starter-Generator Considering Saliency Factor Change and Equivalent Iron Loss Resistance

Research on control strategies of aircraft wound-rotor synchronous starter-generator relies on accurate simulation models. The field current of the main machine is provided by the main exciter through rotating rectifier. This brushless excitation structure requires that the main machine model has the function that both stator and rotor windings can directly connect with electronic components. Large changes of armature current can cause the saliency factor of the main machine to change obviously. In addition, iron loss is significant for the research on efficiency optimization control strategies. In this paper, the characteristics of the saliency factor and iron loss of the main machine operating under different conditions are analyzed. A constant-parameter double-side voltage-behind-reactance model of the main machine considering the equivalent iron loss resistance and the change of saliency factor is derived and established. The accuracy of the proposed model is verified through the computer studies.

Design and experiment of a combined peeling machine for water chestnut

Water chestnut is a characteristic aquatic vegetable in China, and its demand for peeling fresh fruit is increasing rapidly. Aiming at the existing problems of high labor intensity and low efficiency of manual peeling, a combined water chestnut peeling machine was designed, which used a rotary knife to remove bud and root, and a differential friction belts to remove side peel. The performance of the peeling machine was tested with water chestnut from Xiaogan, Hubei Provence. Under the conditions of 200 g feeding mass and 10 r/min rotation speed, the single factor test was carried out with cutting speed as the influencing factor and the cutting rate of bud and root as the evaluation index. The results showed that the cutting rate of fresh fruit of water chestnut bud and root were 79.04% and 83.77% respectively when the cutting speed of rotary knife was 1.2 m/s. In the differential friction belts, high and low linear velocities were taken as the influencing factors, and the side peel removal rate was used as the evaluation index. The side peel removal rate was 84.93% at the high-speed linear velocity of 2.1 m/s and the low-speed linear velocity of 1.58 m/s. The performance of the whole machine was evaluated, and the results showed that the working loss of the combined water chestnut peeling machine was 43.03% and the comprehensive peeling rate was 77.43%, which reached the design requirements. This study can provide a reference for the research and development of water chestnut peeling device.

Magnetic properties deterioration of non-oriented steel due to laser cutting

In the manufacturing process of electrical machines, laser cutting is widely used to produce the laminations of cores. The internal stresses introduced by the high-energy laser beam will lead to deterioration in the magnetic properties of the non-oriented silicon steels. To accurately predict the core losses of the electrical machines, it is important to analyze the deterioration degree and the deterioration mechanism of the non-oriented steel sheets caused by laser cutting. In this paper, first, the local magnetic properties of the non-oriented steel 35WW250 at different positions are measured under the alternating sinusoidal excitation, in which the degradation degree is evaluated based on the core loss from the macroscopic perspective. Second, from the microscopic perspective, the observed magnetic domain patterns at the edge and those evolutions under the excitation of the magnetic field are investigated. The experimental results demonstrate that laser cutting can lead to the magnetic degradation of the non-oriented steels with a transverse depth of 18 mm from the edge. Moreover, the laser cutting process leads to significant variations in the patterns of the magnetic domains at different positions. The magneto-optical observation and local magnetic measurement verified the effectiveness of the analytical method, which is of great significance for the evaluation and improvement of the processing technique of the silicon steels.