Electrical Machining Parameters Research Articles

Precision machining of DMLS Cu electrodes via WEDM: Parameter optimization and predictive modelling for enhanced performance

This study discusses the machinability analysis of copper (Cu) electrodes that are manufactured through direct metal laser sintering (DMLS), an additive manufacturing (AM) process to produce parts that are conductive. This investigation gives the impact of wire electrical machining parameters like peak current, pulse on time and gap voltage over the material removal rate (MRR), surface roughness (SR), and kerf width (KW). The wire electrical discharge machining (WEDM) process is employed on DMLS Cu electrode using Taguchi's L27 orthogonal array design. Due to a high peak current, gap voltage, and pulse on time, a high heat energy and sparking frequency is produced, thereby it increases the MRR of DMLS Cu electrodes in WEDM process. Adversely at high peak current, high thermal loading occurs and thus discharge energy increases, leading to an increased KW. This KW first rises to a certain extent and then drops down as the gap voltage is increase. In order to achieve greater MRR, lower KW, and enhanced SR, grey relational analysis (GRA) was used to establish the ideal combination of parameters: gap voltage = 40 V, peak current = 5 A, and pulse on-time = 16 µs. Furthermore, an impressive 99.85% accuracy rate was achieved in predicting WEDM responses using a 3-27-3 artificial neural network (ANN). All things considered, this work gives insightful information about the machinability of DMLS Cu electrodes and suggests improvements for the EDM procedure.

Experimental study on electrical discharge machining of porous and pure 316L stainless steel

Porous metal materials are widely used in heat-absorbing, biomedical parts and other fields because of their excellent mechanical properties and biocompatibility. Further applications of porous metal materials are inseparable from secondary precision machining. However, traditional cutting methods tend to compromise the original porosity of the material surface. Electrical discharge machining (EDM) is a type of non-conventional machining method which is more preferable to overcome these defects. In the present study, the main target is to investigate the effect of four input electrical machining parameters (current, frequency, efficiency and gap voltage) on the five output responses (material removal rate (MRR), electrode wear, surface roughness (SR), noise and time consumption value of environmental particulate matter (PM2.5)) when electrical discharge machining porous 316L stainless steel and compared with that of pure 316L stainless steel. The Taguchi method was employed to determine the relationship between electrical discharge machining parameters and output responses. The analysis of variance (ANOVA) was used to evaluate the effect of input parameters on output responses. The effects of electrical machining parameters on above responses were analyzed by main effects, and the order of influence was obtained, respectively. Finally, the surface morphology was observed by scanning electron microscope (SEM), and the effect of electrical machining parameters on the characteristics and formation of machined surface of porous stainless steel was mainly analyzed.

A MEMETIC ALGORITHM APPLIED TO INDUCTION MACHINE PARAMETERS IDENTIFICATION BASED ON AN OUTPUT ERROR

Based on an output error, several evolutionary methods have been applied to identify the parameters of an Induction Machine (IM). The main drawback of these methods is their premature convergence in many situations. To overcome this issue and achieve a more accurate solution, this paper proposes a Memetic Algorithm (MA), which combines a Genetic Algorithm (GA) and a local search method. This approach uses the Hooke-Jeeves (HJ) method for the local search as a mutation operator.GA has proven good ability in global search. The HJ method has a good ability to refine the local search and achieve the optimal accuracy solution. The proposed MA, which maintains a tradeoff between exploration and exploitation strategies, is applied to minimize the related objective function to obtain the electrical and mechanical machine parameters. The validation of the method is confirmed by an experiment carried out on an (0.4 kW) IM with parameters estimated using the measured data. Using the estimated parameters, the computed transient and steady-state currents agree well with the measured data.

Double feed inductor generator mathematical model for studying generation modes with unbalance of electrical machine parameters

The analysis of systems using dual power generators revealed a variety of models, most of which are built in the α-β and d-q coordinate systems. Models and control systems are made taking into account the unbalance of the voltage of the electrical network. A model of a three-phase dual-supply generator with the possibility of introducing asymmetry of the electrical parameters of the stator and rotor has been synthesized. Modes with symmetric and asymmetric parameters of the machine windings were modeled. Unbalance is implemented by changing the inductance and resistance of one of the stators and/or rotor phases. In both cases, the required generation mode was obtained both in terms of voltage frequency and its effective value. In the case of unbalance parameters of the windings, asymmetry of the generated voltage and the occurrence of pulsations of the electromagnetic moment with a frequency of 100 Hz were noted. Using the approach to the analysis of the electric power caused by the voltage and current of positive, negative and zero sequences, according to the simulation results, it was noted that in the case of asymmetry, along with the appearance of the components of the negative sequence power, changes in the components of the positive sequence power occur. The indicated power components increase with increasing asymmetry of machine parameters

Critical review on tool wear and its significance on the µ-ECSM process

Micro-electrochemical spark machining (µ-ECSM) is an advanced hybrid machining approach to machine materials, irrespective of their electrical conductivity. This article illustrates the state-of-the-art review of the current research on the wear mechanism of micro-tool electrodes used in the µ-ECSM process. The influence of different electrical and non-electrical machining parameters on tool wear rate, inducing dimensional inaccuracies in the fabricated components, has been addressed. The various parameters of the tool, such as the material, surface morphology and texture, shape, and size, which influence the process performance, have been discussed in detail. The requirement for technological development in the tooling area of the µ-ECSM process has been pointed out. A detailed analysis of the aforementioned areas is present in this article.

The Phasor Diagram of a Superconducting Synchronous Electrical Machine

This paper describes a universal method proposed by the author for the evaluative analytical calculation of the main parameters of synchronous electrical machines, including superconducting ones. Traditional methods for analytical calculation of parameters to build a phasor diagram of electrical machines require a calculation of all dimensions of the active zone, tooth-slot zone and frontal parts of armature windings. All sizes and local states of magnetic circuit saturation are necessary for the calculation of magnetic conductivities. Traditional analytical methods use, among other things, empirical formulas and non-physical coefficients and allow one to calculate only standard machines with classic tooth-slot zones and armature winding types. As a result of drawing a phasor diagram using traditional methods, the angle between the electromotive force and voltage is calculated, which is the machine’s internal parameter and has no major significance for users. The application of modern computer programs for simulation requires a preliminary analytical calculation in order to obtain all dimensions of the three-dimensional model. FEM simulation programs are expensive, require expensive high-performance computers and highly paid skilled personnel. Fast analytical techniques are also required to assess the correctness of the obtained automatic computer simulation results. The proposed analytical method makes it possible to quickly obtain all the main parameters of a newly designed machine (including superconducting ones and those of non-traditional design) without a detailed calculation of the dimensions of the tooth-slot zone and armature end-windings. The characteristic values of load angles are set according to the results of simple calculations, and the desired values, obtained via plotting, represent the inductive resistances of armature winding and inductive voltage drop across it. Results of practical significance, calculated from the voltage diagram, are as follows: the inductor’s magnetomotive force necessary to maintain the nominal load voltage value, regardless of the magnitude (including double overload) and type of the connected load, or the main dimensions of the active zone.

DEVELOPMENT OF THE CONCEPT OF BUILDING DIAGNOSTIC SYSTEMS OF ROTATING ELECTRICAL MACHINES UNDER THE CONDITIONS OF LIMITED INFORMATIONALITY OF DIAGNOSTIC SIGNS

The article examines the peculiarities of the construction of systems for diagnosing rotating electric machines in the real conditions of their operation. It is shown that in the specified modes of operation there is a problem of limited informativeness of input information parameters that can be used to build such systems. At the same time, an additional limiting factor that must be considered when designing and implementing such equipment is the limited possibility of intervention in the design of the electric machine, which is usually limited to the manufacturing plant. As a result of a thorough analysis of the latest research in the direction of the development of diagnostic systems for rotating electric machines, a systematization of the technological parameters of electric machines that are most suitable for use in diagnostic systems was carried out. It is shown that when choosing input parameters of diagnostic systems, it is advisable to consider their informativeness, selectivity, expressiveness and complexity of the acquisition algorithm. At the same time, it is substantiated that the choice of the optimal combination of diagnostic features cannot be considered from the point of view of superposition, since each of them will be characterized by the entropy of selectivity and severity relative to defects of different types. The expediency of choosing the type of input information of diagnostic systems based on the method of evolutionary search is shown. It is demonstrated that the mentioned method allows to more completely cover the search space than, for example, gradient optimization methods, and to obtain a solution close to the optimal one in a relatively short time (a small number of iterations). The concept and typical structural diagram of the system for diagnosing rotating electric machines based on a modified non-standard artificial neural network (ANN) and the structure of the ANN itself, which considers the current mode of operation of the electric machine during diagnosis and is characterized by high adaptability to the object of diagnosis, are proposed. An example of its hardware implementation is given.

Effect on electromagnetic field of the electric machine by gravitational field – An innovative investigation

All the things in nature are under influence of gravitational field, so is the electric machine. It affects not only physical structure of the electrical machine, but also electromagnetic field produced in the stator and rotor of the machine. Power generated in electrical machine, voltage produced, current flows in the machine, all are functions of electromagnetic field. When there is switching on electromagnetic field, immediately it will influence the gravitational field and in turn make variations in the basic parameters of electrical machine. In this paper, examination of the effect of gravitational field on electromagnetic field and its electrical parameters of electrical machines at microscopic level is studied. General electrical machine is assumed in this study. Gravitational field disturbs electric flux density, electric field strength, magnetic flux density, magnetic field strength and in result permeability and permittivity changes. Due to change in these electromagnetic parameters, Inductance (L) & capacitance (C) changes, which in turn alters XL and XC . Finally these changes make effect on current and power of electrical machines.

Partial-Update Kalman Filter for Permanent Magnet Synchronous Motor Estimates Under Intermittent Data

The partial-update Kalman filter (PKF) is an extension of the Schmidt Kalman filter, which can improve the capabilities of the conventional extended Kalman filter for handling model uncertainties and nonlinearities. Herein, we adapt the PKF to estimate the states and parameters of electric machines, particularly in cases with intermittent observations. To account for missing data within the filter, the arrival of new measurements is treated as a Bernoulli process. We show that the estimation error of the proposed filter remains bounded if the system satisfies mild assumptions. Moreover, we show that the prediction error covariance matrix is guaranteed to be bounded if the observation arrival rate has a lower bound. Hardware experiments validate this technique for a surface-mounted permanent magnet synchronous motor.

Model Predictive Current Control With Online Parameter Estimation for Synchronous Reluctance Machine Controlled by High-Frequency Signal Injection Position-Sensorless

Accurate machine parameters and rotor position information are essential in vector-controlled motor drive systems. However, machine parameter variations by various factors such as the current and the temperature degrade the performance of vector control. Also, a position sensor such as an encoder and a resolver increases the drive system cost. This paper proposes model predictive current control (MPCC) with the online parameter estimation for synchronous reluctance machines controlled by a high-frequency signal injection position-sensorless method. This approach removes the need for accurate knowledge about the system and eliminates the need for the position sensor. The proposed method adopts a recursive least-square (RLS) to estimate the electrical machine parameters in real-time. The estimated parameters are used for the deadbeat continuous control set (CCS) MPCC and the position-sensorless control. The high-frequency signal injection method is modified to be suitable for the proposed CCS-MPCC method, ensuring stable operation in the low-speed regions. Simulation and experimental results are provided to verify the performance of the proposed control method.

Research on the machining characteristics of vertical ultrasonic vibration assisted WEDM-LS

ABSTRACT In this paper, a novel composite process technology – Low Speed Wire Electrical Discharge Machining (WEDM-LS) with Vertical Ultrasonic Vibration (VUV) assisted is put forward to improve the performance of traditional WEDM-LS. First, a fluid-solid coupling model of interelectrode flow field and workpiece is established. The simulation result reveals that under the assistance of Vertical Ultrasonic Vibration of workpiece, the velocity of deionized water near the wall of discharge craters is much higher than traditional WEDM-LS or WEDM-LS with the assistance of wire ultrasonic vibration (Wire USV). Therefore, Vertical Ultrasonic Vibration is helpful to the removal of residual debris from the craters. Second, the multiphase flow model of debris, deionized water, and bubbles between electrodes was constituted, and it shows that workpiece vibration frequency is positively correlated with the movement intensity of bubbles and debris, which promotes debris removal throughout the whole processing area. Finally, based on the Taguchi method, the experiments of traditional WEDM-LS, Wire USV assisted WEDM-LS and VUV assisted WEDM-LS were conducted. The workpiece was selected as TiNi-01 shape memory alloy (SMA). The experimental results reveal that under the large electrical machining parameters, Vertical Ultrasonic Vibration assisted WEDM-LS can achieve excellent machining efficiency and quality.

Analytical Model of an Induction Motor Taking into Account the Punching Process Influence on the Material Properties’ Change of Lamination

The technologies of cutting the cores of electric machines change the magnetic properties and the loss of the electrical sheets used, affecting the machine’s parameters, mainly power losses and efficiency. This is particularly important in the case of induction motors, which are a significant consumer of electricity. Therefore, the problem of increasing their efficiency is important from the point of view of environmental impact. The article presents a method of approximating a material’s magnetic properties based on the results of measurements carried out with specimens of various widths. The presented method allows for an approximate representation of the changes in the structure of the material caused by the cutting technology. It is used in the analytical method for calculating motor parameters, and gives results that are in good agreement with the measurement. This method can determine the operating parameters of electrical machines of various sizes and rated powers.

METHOD AND DEVICE OF DIRECT AUTOMATED MEASURING CONTROL OF THE INSULATION OF THE WINDING OF ELECTRIC MACHINES

Today, the vast majority of technological processes, both production and agriculture, are based on the use of electric machines. Among which, a significant part of production equipment requires the use of electric motors, the power of which exceeds hundreds of kilowatts. Such electric machines have also become widespread as generating equipment, where they are an integral part of power plants, both using traditional energy sources (thermal power plants, nuclear power plants, etc.), and renewable (hydroelectric power plants, wind farms, etc.), where the unit power of a single electrical machine is usually higher than in other sectors of economy. When operating such equipment, systems for monitoring a significant number of technological parameters are often used, and in real time it characterizes the modes of their operation. This approach makes it possible to increase the reliability of operation and, with a fairly high probability, to avoid large-scale man-made threats that can be caused by an emergency failure of power electric machines (including powerful electric generators), which are quite often accompanied by the destruction of supporting structures, structural elements of industrial premises and can pose a threat to the life and health of production personnel. But the use of even the most modern systems for monitoring the technical condition does not provide one hundred percent reliability, and when operating electrical machines with a nominal power of the order of units of MW and below, their use can significantly increase the total cost of equipment with a still quite high level of occurrence of a serious man-made accident. Therefore, the development of direct methods and means for measuring the technical parameters of electrical machines in general, and insulation parameters in particular, is an urgent scientific and applied problem. In the article was proposed a new method of direct automated measuring control of insulation of windings of an electric machine, based on the use of combined signals to determine the technical parameters of the insulation of electrical machine units. And also, the design of the measuring control has been developed, it implements the proposed method.

Q-tables formation method for automated monitoring of electromechanical converters parameters with application of linear integral criterion

In the process of functioning working sets with electromechanical converters included in their composition, it is necessary to take into account the influence of endogenous and exogenous disturbances that cause deviations of the parameters of electric machines from the nominal values given by the manufacturer in the appropriate documentation. These deviations of the parameters, even those within the permissible range of changes, have a noticeable effect on the quality of functioning of electromechanical converters and working sets as a whole. During the life cycle of the work of electromechanical converters, their parameters change as a result of natural wear and senescence, which necessitates continuous or periodic analysis and monitoring of the state objects under study. The paper considers a method based on the calculation of the linear integral criterion Q and the formation of Q – tables, which allows monitoring the functioning of electromechanical converters with unstable parameters during operation as part of working sets. Simulink – models of linear integral criterion calculation system and system of automated monitoring of electromechanical DC converter parameters are presented, which allow estimating unstable parameters. In these models static characteristics are implemented in tabular form reflecting the dependencies between the parameters of the electromechanical converters and the linear integral criterion. The results of the study allow us to obtain estimates of changes in the unstable parameters of electromechanical DC converters with the required accuracy.

Complex design of multi-machine electromechanical system of wind generators


 
 
 The direction of modernization of the wind power plant is substantiated, which is aimed at a comprehensive increase in energy efficiency and resource conservation. Taking into account the reasons for the destruction of the teeth of the gear, a constructive scheme of a single-stage gearbox with several output shafts is proposed. This scheme allows you to distribute the output power to several electric machines, which, in turn, reduces the mechanical stress in the area of contact of the teeth of the gears and gears of the output shafts. Due to the division of the output power into several machines, the mass and dimensions of the gearbox are also reduced. The uniformity of power distribution on the shafts can be violated by the discrepancy between the parameters of gears, electromagnetic and mechanical parameters of electric machines. In the proposed design scheme, the uniformity of energy flows along the shafts is ensured by a sequential connection of the phases of the stator windings of electric generators.
 
 

Determination of Changes in the Parameters of Electrical Machines after Repairs to Prevent an Unacceptable Increase in Vibration of the Building Structure

This article discusses the improvement of control methods for electrical machines after repair. These methods allow during testing of an electric machine to determine deviations of parameters that can lead to an increase in the level of vibration and subsequent failure of both the machine itself and the elements of building structures.

Determination of Equivalent Circuit Parameters of a Solid Rotor Asynchronous Electric Machine

The article deal with the determining the equivalent circuit parameters of a solid rotor asynchronous electric machine. To solve the problem, we determined the structure and parameters of a mathematical model using known geometric relationships and parameters of used materials. The least square method is used to determine the equivalent circuit parameters of an unlaminated-rotor asynchronous electric machine. The magnetic field distribution is calculated when the stator winding is supplying with a sinusoidal current and under short-circuit conditions. The imaginary part of the stator phase inductance versus stator current frequency when the rotor is fixed is calculated using the field theory. This dependence is approximated. The system of algebraic equations determining the approximation parameters is non-linear. The Levenberg-Marquardt method provides solution convergence of the equation system when using two or more loops on the rotor. The selection of the initial approximation largely determines the convergence of the solution made by the iterative method. The preliminary studies showed that the use of simplified scheme of the substitution of an asynchronous electric machine with one contour on the rotor is suitable as an initial approximation of parameters. The numerical solution of the equations determined the approximation parameters. The equivalent circuit parameters of high-speed electric generator with solid asynchronous rotor was made as an example of using of the approach under consideration. We need to use three loops on the rotor in the mathematical model of the asynchronous electric machine to take into account the effect of current displacement in solid rotor.

Topology Optimization of Ferromagnetic Components in Electrical Machines

This article presents the topology optimization of ferromagnetic components in electrical machines by using the density method. Explicit expressions of machine performance based on the principle of electromechanical energy conversion are derived and incorporated in the finite element model. Because the gradient-based algorithm is employed for efficient optimization, the performance sensitivities with respect to the design variables are derived subsequently. An optimization framework is then proposed to optimize effectively the electrical machine parameters and performance, such as the flux linkage, back electromotive force, and torque profile including the torque density and torque ripples. Two design examples are reported to confirm the feasibility and effectiveness of the presented topology optimization approach. The accuracy of optimal solutions is verified by using ANSYS MAXWELL, a commercial field analysis software.

Numerical Estimation and Experimental Verification of Optimal Parameter Identification Based on Modern Optimization of a Three Phase Induction Motor

The parameters of electric machines play a substantial role in the control system which, in turn, has a great impact on machine performance. In this paper, a proposed optimal estimation method for the electrical parameters of induction motors is presented. The proposed method uses the particle swarm optimization (PSO) technique. Further, it also considers the influence of temperature on the stator resistance. A complete experimental setup was constructed to validate the proposed method. The estimated electrical parameters of a 3.8-hp induction motor are compared with the measured values. A heat run test was performed to compare the effect of temperature on the stator resistance based on the proposed estimation method and the experimental measurements at the same conditions. It is shown that acceptable accuracy between the simulated results and the experimental measurements has been achieved.

Mathematical modeling of thermal processes in small-size DC electric machines

This article considers small-size electric machines used in various fields of technology, from medical electrical equipment to complex mechatronic systems as part of spacecraft. To obtain satisfactory weight and size parameters of electric machines, it is necessary to take into account many factors that limit the possibility of reduction the machine size. The high energy of modern permanent magnets (250 - 300 kJ/m3) makes it possible to obtain the best weight and dimensons indicators in the designs of brushless direct current machines with excitation from permanent magnets, taking into account the influence of thermal processes.