Electrical Machines Research Articles

DIMENSONAREA ȘI CONSTRUCȚIA TRADUCTOARELOR PIEZOELECTRICE DE VIBRAȚII

The paper presents the construction of piezoelectric accelerometers, the mechano-electrical transfer mode, typical constructions, basic characteristics, and theoretical approaches to the vibration phenomenon appearing in accelerometry and calculation possibilities of the various characteristics of the transducers. In the second part of the paper, the functional testing of such a transducer is also presented, piezoelectric vibration transducers being useful for vibration determination and dynamic balancing of electric machines. In general, vibration transducers provide, through mechano-electrical conversion according to different principles, an electrical signal directly proportional to a vibration parameter (acceleration, travel speed, amplitude); depending on the principle, they can be piezoelectric, electrodynamic, inductive, capacitive, resistive or based on the Hall effect, with magnetic fluids, interferometric, laser, servo-accelerometers, etc. Since there is no universal accelerometer, each one is intended to encompass the characteristics of a concrete application best, the way of stressing the photosensitive medium in the first place, the design,, as well as the other characteristics, vary from one construction to another.

AC Loss Analytic Method and Optimization of Litz Winding for High-Speed Electrical Machines

AC Loss Analytic Method and Optimization of Litz Winding for High-Speed Electrical Machines

Investigation and comparison of permanent magnet rotors produced by different additive manufacturing methods

The advancements in technology have led to a growing interest in additive manufacturing owing to its numerous benefits such as increased degree of freedom, high flexibility, and material conservation. It has gained particular attention in the production of electrical machines and their active components such as windings, electrical insulation, magnetic core packs, and permanent magnets. This paper investigates the use of two methods, namely fused deposition modeling and cold spray, in the production of hard magnetic components for rotors with surface-mounted magnets. A comparative study was conducted through a combination of finite element simulations and experimental tests.

SISTEM PENTRU DIAGNOSTICAREA COMPLEXĂ A STĂRILOR MAȘINILOR ELECTRICE ROTATIVE DE MEDIE ȘI MARE PUTERE (ACRONIM SDCME)

The company SIMTECH RESEARCH SRL completed, in the year 2023, the Project entitled System for the complex diagnosis of the condition of medium and high power rotating electrical machines - acronym SDCME, and in this work the objectives, activities and results of this project are briefly presented, together with the conclusions resulting from the realization of the project, as well as some perspectives on future research.

High-sensitive state perception method for inverter-fed machine turn insulation based on FrFT-Mel

Amidst the swift advancement of new power systems and electric vehicles, inverter-fed machines have progressively materialized as a pivotal apparatus for efficient energy conversion. Stator winding turn insulation failure is the root cause of inverter-fed machine breakdown. The online monitoring of turn insulation health can detect potential safety risks promptly, but faces the challenge of weak characteristics of turn insulation degradation. This study proposes an innovative method to evaluate the turn insulation state of inverter-fed machines by utilizing the fractional Fourier transform with a Mel filter (FrFT-Mel). First, the sensitivity of the high-frequency (HF) switching oscillation current to variations in turn insulation was analyzed within the fractional domain. Subsequently, an improved Mel filter is introduced, and its structure and parameters are specifically designed based on the features intrinsic to the common-mode impedance resonance point of the electrical machine. Finally, an evaluation index was proposed for the turn insulation state of inverter-fed machines. Experimental results on a 3kW permanent magnet synchronous machine (PMSM) demonstrate that the proposed FrFT-Mel method significantly enhances the sensitivity of turn insulation state perception by approximately five times, compared to the traditional Fourier transform method.

RÓWNANIA POLA ELEKTROMAGNETYCZNEGO W ŚRODOWISKU NIELINIOWYM

The paper proposes electromagnetic field equations from the point of view of their adaptation to numerical methods. Maxwell's equations with partial derivatives are used, written concerning field vectors, which most fully reproduce the picture of physical processes in electrical engineering devices. The values of these vectors provide comprehensive information about the field at any spatio-temporal point. The concept of creating mathematical models of electrical devices adequate to physical processes has been developed. Mathematical transformations are carried out according to the rules of differential calculus. Dynamic processes in the elements of electrotechnical devices were analyzed using the apparatus of mathematical modeling. An algorithm for implementing differential equations with partial derivative numerical methods using computer simulation was implemented. The obtained results made it possible to understand the nature of electromagnetic phenomena in nonlinear media. The paper provides calculations of the field parameters in a flat ferromagnetic plate and the groove of the rotor of an electric machine.

Indirect Field Oriented Control of Induction Motor

The various control strategies for the control of the inverter-fed induction motor have provided good steady-state but poor dynamic response. In the last decades, many control techniques have been developed providing good performance. Field-oriented control is one of the most significant control methods for high performance AC electric machines and drives. In particular, for induction machines, indirect field oriented control is a simple and highly reliable scheme which has essentially become an industry standard. With the advent of the vector control methods, an induction motor can be operated like a separately excited dc motor for high performance applications. The speed control is observed in closed-loop control applications. The speed regulation is achieved with a PI controller which converts the command speed into the command torque and therefore the speed of the drive. In this paper PI controller base indirect field orientation control of 3-phase 415V, 50Hz Induction motor using cascaded multilevel inverter is proposed in MATLAB/SIMMLINK 7.10.0 (R2010a).

Analisis Pengontrolan Water Treatment Bandara Djalaluddin Menggunakan Sistem Kerja Star Delta

In knowing how efficient the use of the Star Delta circuit is, the need for a circuit on a 3 Phase motor and how to apply the circuit to a 3 Phase water pump motor. The research was conducted at Gorontalo Djalaluddin Airport which is located in Isimu Sel, Tolotio, Tibawa District, Gorontalo Regency, Gorontalo, Indonesia. The research was carried out using data collection methods. An example of the application of a star delta circuit to a water pump motor. An electric motor is included in the category of dynamic electric machines and is an electromagnetic device that converts electrical energy into mechanical energy. Electric motors in the industrial world are often referred to as the industrial "work horse" because it is estimated that in an industry the average electricity consumption for electric motors is around 65-70% of the total electrical load in the industry. Three-phase electric motors have initial current characteristics that are 5 to 7 times the nominal current of the electric motor itself, but can be overcome by a star (Y) - triangle (Δ) starting system. The aim of this study was to examine how the triangular (Δ) star (Y) starting system works for 3 phase induction motors. The methods used include literature studies, collection of tools and materials, design, tool testing and data collection. From the results of testing the triangular (Y) star starting system (Δ) effectively suppresses the high starting current of the electric motor operation with the value of the measurement results of electric current using a star connection (Y) in the R phase of 0.6 A, the S phase of 0.8 A and the T phase of 0.6 A. And using a triangular relationship (Δ) in the R phase of 7.5 A, the S phase of 8.5 A and the T phase of 8.3 A.

Methods of determining internal damage in power transformers

Due to the variety of defects that arise in electrical machines, it is necessary to use more effective methods for monitoring their condition. All over the world research and development of new means and methods for monitoring powerful electrical machines during their operation is underway. Some examples of recent advances are vibration diagnostic methods for assessing the compaction of components inside a transformer, acoustic and electrical systems for monitoring partial discharges, data processing using digital methods, and new sensors for continuous monitoring of gases and moisture in oil, as well as hot spot temperatures. Additionally, thermal imaging testing of power equipment is also an important tool to ensure reliable operation. It is believed that the most effective method is gas chromatographic oil analysis, which can identify most defects in oil-filled equipment. During the operation of powerful electrical machines, the use of existing non-destructive testing methods does not allow a complete assessment of the condition of the main parts of the equipment, as an analysis of damage locations shows, 25% are damage to the core and windings. Effective monitoring of the condition and determination of the performance of transformers is of particular importance, since they are key elements in the operation of nuclear power plants. The paper considers the possibility of using the eddy current testing method; determining a defect in magnetic core steel is based on fixing the unevenness of the magnetic field on the horizontal or vertical planes of a yoke or rod consisting of electrical steel plates. Monitoring and evaluating the functioning of existing equipment, detecting deficiencies in the early stages of their development, when repair costs are still minimal, and preventing emergency failures become a priority. In accordance with the growth rate of detected deficiencies, monitoring is carried out from time to time or continuously, the maximum number of monitored characteristics is achieved when the transformer is fully tested to determine its functionality.

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.

Monitoring of Stator Winding Insulation Degradation through Estimation of Stator Winding Temperature and Leakage Current

Switched Reluctance Motors (SRMs), Permanent Magnet Synchronous Motors (PMSMs), and induction motors may experience failures due to insulation-related breakdowns. The SRM rotor is of a non-salient nature and made of solid steel material. There are no windings on the rotor. However, the stator is composed of windings that are intricately insulated from each other using materials such as enamel wire, polymer films, mica tapes, epoxy resin, varnishes, or insulating tapes. The dielectric strength of the insulation may fail over time due to several environmental factors and processes. Dielectric breakdown of the winding insulation can be caused by rapid switching of the winding current, the presence of contaminants, and thermal aging. For reliable and efficient operation of the SRMs and other electrical machines, it is necessary to take into account the physics of the winding insulation and perform appropriate diagnostics and estimations that can monitor the integrity of the insulation. This article presents the estimation problem using a Genetic Algorithm (GA)-optimized Random Forest Regressor. Empirical properties and measurable quantities in the historical data are utilized to derive temperature and leakage current estimation. The developed model is then combined with a moving average function to increase the accuracy of prediction of the stator winding temperature and leakage current. The performance of the model is compared with that of the Feedforward Neural Network and Long Short-Term Memory over the same winding temperature and leakage current historical data. The performance metrics are based on computation of the Mean Square Error and Mean Absolute Error.

Multi-Objective Optimization of Yokeless and Segmented Armature Machine for In-Wheel Traction Applications Based on the Taguchi Method

For electrical machines with complex structures, the design space of parameters can be large with high dimensions during optimization. Considering the calculation cost and time consumption, it is hard to optimize all the design parameters at the same time. Therefore, in that situation, sensitivity analysis of these design parameters is usually used to sort out crucial parameters. In this paper, the sensitivity analysis-based Taguchi method is applied to optimize the axial-flux permanent magnet (AFPM) machine with yokeless and segmented armature (YASA) topology for an in-wheel traction system. According to the key parameters and their sensitivity analysis, the optimal machine scheme to meet the performance requirements can be formed. In this case study, the machine performance is improved significantly after optimization. Lastly, the experimental results verify the accuracy of the model used in this study.

The Juxtaposition of Our Future Electrification Solutions: A View into the Unsustainable Life Cycle of the Permanent Magnet Electrical Machine

Electrification is increasing in prevalence due to the importance placed on it for achieving global net zero targets. This has led to the proliferation of electrical mobility, including the wide-scale production of passenger vehicles, personal mobility devices and recent announcements regarding electrically powered aircraft, as well as in energy production. Electrical machines provide a cleaner source of energy during operation in comparison to their traditional fossil-based alternatives. The uncertainty and lack of transparency hanging over these green credentials can be attributed to how these products are manufactured and then disposed of at the end of their life. For them to be a truly sustainable solution, improvements need to be made across their entire life cycle. With the projected increase in their numbers due to the advancement of electrification, this current life cycle is not sustainable, directly opposing the intention of these products. This paper will introduce the current demand and challenges. It will also present these motors broken down into their constituent parts and follow each through their typical lifecycle. This paper presents the typical current life cycle of permanent magnet electrical machines, demonstrating the environmental issues associated with the current linear life cycle, and proposing alternative practices, to ease the environmental burden.

A novel approach towards parametric assessment of reliability and resilience of high voltage mica‐based insulation systems by statistical analysis of experimental failure data

AbstractInsulation systems in high‐voltage electric machines play a pivotal role in the reliable operation and longevity of the equipment. Mica‐based insulation materials have proven to possess and maintain excellent dielectric properties in the long run and prevent premature insulation degradation. Numerous qualifications tests, such as voltage endurance, are outlined in IEC and IEEE standards. The authors, however, take a different parametric approach, opting for reliability assessment of insulation systems using derived three‐parameter Weibull models. Therefore, instead of simple pass–fail criteria, empirical data is employed to determine failure rate probabilities quantitatively and objectively. Experimental data, including breakdown, dissipation factor, and partial discharge measurements, are used to construct the Weibull distribution model to predict fault and failure rates and calculate hazard functions. The rigorous examinations interpreted through the analytical model help assess insulation system resilience and particularly the impact of electrical field stress and mica content. Variation of electrical stress from 66.75 to 71.20 V/mil demonstrated how the mean time to failure of the system changed from 146.4 to 85.1 at 3 Un, hence identifying opportunities for design improvement and uncovering performance boundaries. Ultimately, the developed framework enhances comprehension of insulation system failure probabilities, guiding design decisions and ensuring a secure and reliable operation of electrical machines across applications.

A Study on the Performance of the Electrification of Hydraulic Implements in a Compact Non-Road Mobile Machine: A Case Applied to a Backhoe Loader

This work presents a study of the performance of prime mover and hydraulic implement electrification in a backhoe loader. The results are validated through simulation and experimental tests. The construction and agriculture sector has grown in recent years with the aid of compact non-road mobile machines. However, as is common in fossil fuel-powered vehicles, they significantly contribute to increasing emissions. Previous research has primarily relied on powertrain electrification to address the low-efficiency drawbacks. Notably, compact off-road vehicles comprise implements less discussed in the literature. A hybrid series topology is employed, where the rear implement is driven by an electrical drive and the Diesel engine is coupled to a generator. A rule-based energy management strategy is applied. The operation of the Diesel engine and electrical machines in optimal points of the efficiency maps are the basis of the analysis. The design is validated using simulations and experimental tests in a commercial backhoe loader as a benchmark. Experimental and simulation results obtained from the hybrid series backhoe loader applied to the hydraulic implement show a 33% reduction in fuel consumption, demonstrating the effectiveness of electrification in reducing emissions and fuel consumption of compact non-road mobile machines.

A numerical procedure to obtain ideal piston trajectories and key design parameters for a hydrogen-fuelled resonating free piston generator

A new numerical procedure is presented to enable a hydrogen-fuelled two-stroke resonating free-piston generator target ideal Otto cycles to provide tracking paths for feedback control to maximise efficiency. Piston trajectories and design parameters are obtained for specified power, compression-ratio, and air-fuel-ratio. These parameters include scavenge port locations, heat release position, equivalent bottom-dead-centre position, and an electrical machine constant which is generally power-switched to take two values within a cycle. The main objectives of the paper are to develop the numerical procedure, and to demonstrate its use in finding a generator with maximum efficiency, and a generator with a single electrical machine constant, avoiding in-cycle power switching. To develop the procedure, a multi-physics generator model provides kinematics to an energy equation, culminating in a novel two-stage procedure. Stage-1 involves iteration and minimisation; Stage-2 just involves minimisation. Testing by simulation involves a 14-kW generator case study with compression ratio of 9, lean air-fuel equivalence ratio of 0.4, plus friction and electrical machine losses. An overall maximum generator efficiency of 54.9% is obtained using the procedure, compared to 51.3% without power switching. Computationally, the two-stage procedure proves highly efficient, typically taking around 11 min in total to complete on a desktop computer. The novelty of the procedure is its ability to optimally design and operate a hydrogen-fuelled resonating free-piston generator to meet a target specification, thereby offering a potentially inexpensive way to decarbonize transport, particularly in heavy duty applications.

Enhancing Heat Transfer Efficiency in Permanent Magnet Machines through Innovative Thermal Design of Stator Windings

This paper investigates innovative methods for enhancing heat transfer efficiency in high-power permanent magnet electrical machines. The objectives are to quantify the effects of increasing the air speed, increasing the turbulence intensity, and introducing the spacing between windings on cooling performance. The cooling of stator windings is studied through experimental wind tunnel testing and Computational Fluid Dynamics (CFD) modelling. The CFD model is validated against wind tunnel measurements to within 4 Kelvin (K). The results demonstrate that each enhancement method significantly improves the cooling capability. Increasing the air speed from 10 m/s to 40 m/s reduces the winding hotspot temperature by 34%. Introducing a high turbulence intensity of 40% leads to a 21% lower hotspot temperature compared to 0.5% turbulence intensity. Creating a 1.5 mm spacing between coils also substantially improves convection and conduction heat transfer. Overall, combining these optimised design parameters yields over a 40% reduction in hotspot temperature compared to the original design. This research provides practical guidance for maximising heat transfer efficiency in high-power permanent magnet machines, without increasing complexity. The findings will lead to higher machine efficiency, reliability, and longevity for aerospace and other applications.

Determination of loss components in the steel of magnetic circuits of electric machines

Determination of loss components in the steel of magnetic circuits of electric machines

Design and fabrication of circular sheet metal shearing machine

The growing use of sheet metal in various industries such as automotive, packaging, medical appliances, cylinder production, Apparatus construction, Tank construction, Aircraft bodies, Missile production, Satellite dishes, road building and road signs, and household appliances, is attributed to its ease of manufacturing, handling, and use. To meet customer demands, sheet metal product manufacturing industries are working towards producing circular feature products of good quality at a large scale and low cost. To this end, this research emphasis the design, analysis, and fabrication of an electric circular sheet metal shearing machine, this would replace the punching and blanking operations and reduce scrap value from the stock material. The research includes concept design, detail design and analysis, assembly, 3D modelling, and fabrication of the Machine.

Design, scalable construction, and test of optimal linear Halbach arrays for mobile applications

Advancing permanent magnet arrays for linear electric machines is a compelling endeavor with the potential to further improve efficiencies in the fields of power generation or passenger and cargo transportation. Permanent magnets offer an unparalleled advantage by providing a consistent and efficient source of magnetic flux density without the need for external power input. This remarkable property allows for the development of smaller, lighter, and more energy-efficient electric machines, making them ideal for applications in several industries. Here, we present the design of an optimal linear Halbach array with a sinusoidal distribution of the magnetic flux density component Bz perpendicular to the surface of the array. A large scale and easy scalable six-segmented Halbach array has been built without the use of a steel backplate enabling a lightweight and compact design. Numerical results of the magnetic flux density distributions are calculated by relying on finite element methods and are compared with experimental measurements of the magnetic flux density, showing good agreement. The demonstration revealed that, with an optimal magnet configuration, the absence of a backplate does not result in any diminishment of magnetic flux density strength.