Salient-pole Synchronous Machine Research Articles

Simplified Current-Equivalent Circuit Models of Synchronous Reluctance Machines and Salient Pole Synchronous Machines Considering the Reluctance Torque

This paper describes a simplified one-phase equivalent circuit model of three-phase salient pole synchronous machines and synchronous reluctance machines. The model represents the pole saliency as a susceptance, with a magnitude based on the pole saliency and a phase angle based on twice the load angle. The reluctance torque itself is then modeled equivalent to a conductance. The model is made as an extension to Norton equivalents, where the internal inductance is connected as a shunt. This approach shares similarities to the magnetization shunt branch in circuit models of transformers and induction motors. The model is derived using the rotating dq-frame, using Park transform and two-reaction theory. The model is then rewritten to better fit one-phase equivalent circuit models, with the terminal voltage as the angular reference. The resulting two-pole model can then more easily be combined with basic circuit theory, thereby synthesizing dq-theory and phasor circuit models.

Control laws of a salient pole synchronous machine in a mine electric locomotive

Relevance. The need to find effective control of a traction synchronous motor with permanent magnets in a mining electric locomotive under conditions of limitation of current and voltage supplied to its windings from an autonomous power source. Aim. To choose a control law that ensures an increase in a mine electric locomotive mileage on one battery charge with its speed growth. Object. Control laws of a salient pole synchronous motor with permanent magnets of a mining electric locomotive; laws of current control along the transverse axis; control by the current minimum and control by minimizing the reactive power of a salient pole synchronous machine. Methods. Analysis of the state of the electric machine with different formation of control of an electric drive in the mine electric locomotive. The main limiting indicators of an electric machine with voltage and current limitation were considered. For each control law, the results of mathematical modeling are shown in graphical and tabular form. Results. The analysis of the current control law along the transverse axis demonstrates a significant increase in reactive power with increasing load. In an hourly mode of operation, the reactive power exceeds the active power spent on the movement of the electric locomotive. When limiting the current and voltage, the minimum current control allows you to increase the electromagnetic torque by 12.7% in hourly operation. The maximum engine speed is increased by 13%. The maximum power spent on the electric locomotive movement increases by 33%. Reactive power is reduced by 29%. With reactive power minimization, despite the decrease in the electromagnetic torque in the hourly mode of operation by 4.8%, the maximum possible engine speed increases by 53%, the power spent on the electric locomotive movement increases by 50%.

Detection of Rotor Field Winding, Damper Bar, and Eccentricity Faults in Salient Pole Synchronous Machines With the Pole Drop Test

The pole drop test is the most widely applied means of detecting shorted turns in the rotor field winding of salient pole wound field synchronous machines (WFSM). It is a simple off-line test that relies on detecting the asymmetry between the voltage drop in the windings of each pole with ac voltage applied to the field winding terminals. Although it can provide sensitive detection of shorted field turns, it is also influenced by asymmetries in the motor produced by defects or imperfections in the rotor poles or damper bars. In this work, the feasibility of using the pole drop test for detecting damper bar and eccentricity faults in addition to shorted field windings is investigated for the first time. The change in the impedance of each pole under the fault conditions is analyzed from the electrical equivalent circuit and finite element (FE) simulation. Based on the analysis, it is shown that the 3 faults can be detected and classified from the impedance or voltage distribution with the pole drop test. Experimental tests performed on 4 pole, 30 kVA and 6 pole, 5.5 kVA salient pole WFSMs confirm that the 3 faults can be identified as claimed.

Mathematical model for salient-pole synchronous motor field-coil calculation and optimization

To optimize the parameters of the salient-pole synchronous machine field-coil and achieve specified technical and economic characteristics, an optimization problem with restrictions, which belongs to the class of nonlinear programming problems, was solved. Mathematical model for salient-pole synchronous motor field-coil calculation and optimization, an algorithm and a computer program were created. The mathematical model for calculation and optimization of salient-pole synchronous machine field-coil provides a possibility to design a single-row field-coil winding based on known dimensions under the following restrictions: the minimum distance between the coils of adjacent poles must not be less than the permissible value, the temperature of the coil above the ambient temperature must not be greater than the maximum permissible for the chosen insulation class of the value of the coil, according to the conditions of single-row coils manufacturing, conductor cross-section area should not be greater than the permissible value, and the ratio of the width of the conductor to its height should be within certain limits, the dimensions of the conductor should correspond to standard values. The optimization criterion (objective function) is the copper consumption or cost of the coil, the consumption or cost of pole core steel, power losses in the coil, the total cost of copper and pole steel, the total costs of machine manufacturing and its operation. The choice of the optimization criterion depends on the purpose of the machine and the requirements placed on it. In this problem, each of these criteria is a function of one variable - the height of the field-coil.

A Pre-Sizing Method for Salient Pole Synchronous Reluctance Machines with Loss Minimization Control for a Small Urban Electrical Vehicle Considering the Driving Cycle

In this paper, a design methodology for synchronous reluctance machines (SynRM) working with variable torque and speed profiles was presented. Unlike conventional solutions which size the machine considering a reduced number of working points in order to reduce the computation time, the solution proposed in this paper takes into account all the points which allow for better management of the constraints along the cycle to avoid an oversizing of the machine. To solve this problem with a reduced computation time, the geometry of the motor as well as the control strategy were optimized in two steps. In the first step, the d-q axis stator currents were analytically expressed. In the second step, the geometry was optimized with the use of a genetic algorithm. As an application of this method, the case of a small and low-cost electric vehicle (EV) was chosen with the objective of minimizing both the mass and the energy lost for the standardized urban dynamometer driving schedule (UDDS). The method was based on the use of a 1-D analytical model which was validated by a 2D finite element analysis (FEA).

ЗОВНІШНЯ ДЕМПФЕРНА СИСТЕМА РОТОРА ЯВНОПОЛЮСНОЇ СИНХРОННОЇ МАШИНИ

A comparative analysis of the characteristics of the salient pole synchronous machine for two variants of the rotor damping system design was performed by mathematical modeling methods. In the first embodiment, a traditional (internal) damping rotor system is used, which is made of electrically conductive rods immersed in the surface of the poles. In the second em-bodiment, the external damping system of the rotor is made in the form of conductive sheets fixed to the surface of the poles. It is noted that the external damping system of the rotor provides better asynchronous characteristics and is characterized by more uniform heating, which reduces the thermomechanical loads of structural elements. This design increases the reliability of the machine not only in the event of short-term asynchronous modes of operation, but also in the event of uneven air gap between the stator and rotor, which usually occurs during long operation of high-pole synchronous machines, such as hydro generators. References 10, figures 6.

Combining Schwarz–Christoffel Mappings and Biot–Savart Law to Calculate the Clamping Plate Field in Large Salient Pole Synchronous Machines

A new calculation approach for the contribution of the stator end winding field to the clamping plate field in large synchronous machines based on Biot–Savart (BS) law and Schwarz–Christoffel (SC) mappings is proposed in this article. The new field calculation appeals due to its low computational cost in the range of hundreds of milliseconds. The field normal to the clamping plate as well as the tangential clamping plate flux is compared to magnetostatic 3-D finite element analysis (FEA) simulations for multiple operating points of a test generator geometry, with both calculation approaches being in good agreement.

Agro-residues for clean electricity: in-lab trial of power generation from blended cocoa-kolanut wastes

As a way of wastes-to-voltage conversion, experimental benchtest trial of electricity generation from a blend of cocoa and kolanut harvest by-products is presented in this study. Bioethanol obtained from the blend, through a process of alcoholic fermentation, was mixed with gasoline at specific proportion and employed to fire a spark ignition engine that served as a prime-mover in driving a four-pole three-phase salient-pole synchronous machine. Performance of the driving machine, as the fuel-mix proportion and its speed of rotation varied, was studied. Likewise, the electric power output characteristic of the driven machine, when operated at its rated synchronous speed, was examined. It was found that the driving machine performed better on mixed fuel than pure gasoline. There were gradual increases in the torque and the power developed by the machine as the proportion of ethanol in the fuel-mix and the rotational speed increased. While the highest values of torque and power developed on using pure gasoline were 12.4 Nm and 2574 W respectively at 1900 rpm, 13.1 Nm torque and 2953 W power were obtained from the machine when ignited with 10%-bioethanol fuel-mix at the same speed. Also, with 90 Vdc excitation voltage and rotation at 1500 rpm synchronous speed, the driven machine continuously generated electricity at 207.6 Vrms (line-to-line), 1.169 A, 0.698 power factor, 48.17 Hz, 0.294 kW output. This study demonstrated the possibility of continuous generation of electric power from cocoa and kolanut wastes. Result obtained from the laboratory-based trial indicates that at such agricultural regions that are advantaged in the production of the two crops, harvest residues of the crops can be explored as a steady source of biofuel for off-grid microgrid electrification.

Comparative study of permanent magnet synchronous machine vs salient pole synchronous machine in high temperature application

This paper presents the sizing and the comparison of two synchronous machines. The purpose is to design a high temperature dedicated machine with the same performance and volume as a permanent magnet machine. To compare the machines, torque has been chosen as a reference indicator and not the efficiency which will be not so good for the high temperature machine. A salient pole wound rotor is chosen with anodized aluminum tape as windings. Works presented should be considered as preliminary studies leading to the conception of a prototype.

Influence of Rotor Eccentricity on the Reliability of the Pole Drop Test for Salient Pole Synchronous Machines

The pole drop test is the most common test for detecting inter-turn insulation failure in the rotor field winding of salient pole synchronous machines. Shorted field turns are detected by comparing the voltage drop across each rotor pole with ac voltage applied to the field winding terminals. It is a simple and effective test that is usually performed with the rotor inserted for convenience and high sensitivity. In this work, the influence of rotor eccentricity on the pole drop test is analyzed. It is shown that anomalies in the airgap can interfere with the pole drop test to cause false positive indications. Alternative test options immune to false indications are also suggested in this letter. The analysis and test options for screening false indications due to eccentricity are verified on 4 and 6 pole, 5, 5.5, and 30 kVA synchronous machines under emulated fault conditions. It is shown that eccentricity interferes with the pole drop test and that testing under dc excitation is immune to eccentricity although the sensitivity is lower, which are not reported elsewhere.

A New Interpretation of the Steady-State Two-Reaction Theory of a Salient-Pole Synchronous Machine

This work contributes two improvements to the well-established two-reaction theory of a salient-pole synchronous machine. Namely, a single circuit is proposed that explicitly accounts for the saliency in the machine. By defining new machine reactances and using a current-controlled voltage source, the proposed single circuit proposed provides an alternative to coupled <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> - and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i> -axis circuit models. The new reactances are also used in a revised phasor diagram to make apparent the internally developed power of a salient-pole synchronous machine that is similar to a round-rotor synchronous machine. The revised two-reaction theory is illustrated using the mathematical model of a three-phase salient-pole synchronous machine whose equations are derived using complex space vectors instead of traditional matrix transformations. A detailed derivation is presented and the resulting equations can directly be used to solve for the steady-state operating EMF and power angle from the terminal voltages and currents in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">abc</i> coordinate system. The ease of their application is demonstrated using a numerical example of the steady-state circuit equations and the revised phasor diagrams.

Model of implicit pole electric machine based on mathematical formulation of magnetic field in air gap

When modeling transient processes in electric power systems, the issue of designing reliable models of electrical machines is of great interest. The most difficult task is to design the models of synchronous and asynchronous machines. The purpose of the project is to develop mathematical models of synchronous and asynchronous machines based on a generalized model of an implicit-pole machine that considers the change of rotor speed, geometric shapes, and the type of rotor and stator windings. Methods of mathematical modeling of electromagnetic fields in the air gap based on Maxwell equations and methods of the theory of electrical circuits are applied. A system of nonlinear differential equations is considered as a mathematical model of a generalized implicit-pole machine. The key assumption made is the high magnetic permeability of the stator and rotor cores. Technical data of real electric machines have been used for verification. Mathematical models of an implicit pole synchronous machine and an asynchronous machine with a phase rotor have been developed. These models can be used to analyze transient processes in the aggregate without dividing them into electromagnetic and electromechanical ones. The novelty of the models is the fact of non-sinusoidal distribution of the magnetic field in the air gap, various types of multiphase AC windings and rejecting the principle of constant rotation frequency at the time step of the simulation. The proposed mathematical models can be used to solve design problems, to analyze the modes of electric power systems, the operation of relay protection and automation of electric power facilities, and emergency automation. In the future, the equations that consider the influence of the damper circuits and the peculiarities of the windings will be added to the developed mathematical models. The purpose of further research is to develop models of salient-pole synchronous machines and asynchronous machines with a squirrel-cage rotor.

Research of dampher system damage physical processes of synchronous machines rotor

The physical processes in the damper system of the rotor with the appearance of a static eccentricity of the rotor for two types of salient-pole synchronous machines - a capsule hydrogenator SGK 538/160-70M with a capacity of 22 MW and a synchronous generator with a capacity of 500 kW were investigated by means of mathematical modeling. A field mathematical model has been developed that takes into account the combined action of three physical fields of different nature: electromagnetic, temperature and field of thermomechanical stresses, and makes it possible to evaluate the heating and three-dimensional distribution of thermomechanical stresses in the structural elements of the rotor damper system of a salient-pole synchronous machine. These physical processes cause gradual destruction of the structure of the rotor damper system. It is proved that the primary cause of degradation and damage of the damping system of the rotor of an open-pole synchronous machine is the uneven distribution of induced currents in the rods at the poles of the rotor, which occurs when the machine works asynchronously or with the appearance of rotor static eccentricity. The largest induced currents and heat occur in the rods located at the edges of the pole pieces, while the central rods at the pole are heated significantly less. This asymmetric heating of the damping system of the rotor leads to significant thermomechanical stresses in the elements of the damping system of the rotor, which significantly depend on the magnitude of the eccentricity and slippery of the rotor in asynchronous mode. The magnitude of the total thermomechanical stresses in the rods is influenced not only by axially directed forces but also by transverse forces in the end short-circuiting elements. At considerable slippery and eccentricities there are inadmissibly big breaking forces which break cores and face short-circuiting elements of a damping system of a rotor. According to the results of the analysis, the heating and thermomechanical stresses of the structural elements were determined and recommendations for its structural improvement were given.

Flux Estimator for Salient Pole Synchronous Machines Driven by the Cycloconverter Based on Enhanced Current and Voltage Model of the Machine with Fuzzy Logic Transition

Flux estimation is a key feature of the field-oriented control for the electrically excited synchronous machine which enables the high-performance, high-dynamic drive behavior. In this work, an electrically excited synchronous machine flux estimator based on a current and voltage model is proposed. In this case, the transition between the estimators is done with a fuzzy logic set of rules. The flux estimator based on the current model of the machine in this paper considers the saturation and cross-coupling effect in both axis and it is suitable for applications where a limited amount of the machine data is available. The flux estimator based on the voltage model is specially designed for the drives where high voltage and current ripple is present under normal operating conditions, e.g., like in cycloconverter applications. To exploit all the advantages of both models, a fuzzy logic transition is proposed based on multiple choices which manages the transition between the models based on a speed and torque reference. The proposed flux estimator is experimentally verified on a cycloconverter fed salient-pole electrically excited synchronous machine. The experimental results clearly show that the proposed flux estimator enables the accurate and stable operating conditions for different operating points of the cycloconverter-fed salient-pole electrically excited synchronous machine.

An experimentally determined field winding model with frequency‐dependent parameters

In this work a set of experimental procedures is presented for determining the main electrical distributed parameters of the field winding in salient pole synchronous machines. It applies to the el ...

ВПЛИВ РЕЖИМНИХ І ЕКСПЛУАТАЦІЙНИХ ФАКТОРІВ НА ДЕМПФЕРНУ СИСТЕМУ РОТОРА ЯВНОПОЛЮСНОЇ СИНХРОННОЇ МАШИНИ

The physical processes in the damping system of the salient-pole synchronous machine rotor, which cause the gradual destruction of its structure, have been studied. In particular, the distributions of currents, temperatures and thermomechanical stresses in the damping system rods during its operation in asynchronous and asymmetric modes of operation, as well as in case of rotor eccentricity. A field mathematical model has been developed that takes into account the combined action of three physical fields of different nature: electromagnetic, temperaturic, and thermomechanical stress fields, and allows estimating heating and thermomechanical loads in the damping system of the rotor of the salient-pole synchronous machine. According to the results of the analysis, the heating and thermomechanical loads of the structural elements were determined and recommendations for its structural improvement were given. References 9, figures 9, tables 1.

Analytical calculations of electromagnetic quantities for wound rotor salient-pole synchronous machines

PurposeThis paper aims to present an analytical electromagnetic model for wound rotor synchronous machines with a salient-pole rotor structure based on the two-dimensional subdomain technique.Design/methodology/approachThe machine is divided into five active sub-regions: stator slots, stator slot openings, air gap, rotor slots and rotor slot openings. For each sub-region, the governing partial differential equations are derived and solved analytically.FindingsThe magnetic flux density distributions in all active sub-regions are analytically computed and other quantities such as back-emf, inductances, electromagnetic torque and unbalanced magnetic forces are also analytically calculated. The results of the analytical model are compared to those obtained from the finite element analysis to show the accuracy of the proposed model.Originality/valueThe two-dimensional analytical model of a wound rotor salient-pole synchronous machine using the sub-domain technique is the main contribution of the research.

Agro-Residues for Clean Electricity: In-Lab Trial of Power Generation from Blended Cocoa-Kolanut Wastes

As a way of waste-to-voltage conversion, a laboratory-based test trial of electricity generation from a blend of cocoa and kola nut harvest by-products is presented in this study. Bioethanol obtained from the blend through a process of fermentation is mixed with gasoline at specific proportions and employed to fire a spark-ignition engine that serves as a prime-mover in driving a four-pole three-phase salient-pole synchronous machine. Performance of the driving machine as the fuel-mix proportion and its speed of rotation varies is studied. Likewise, the electric power output characteristic of the driven machine operated at its rated synchronous speed is examined. It is found that the driving machine performs better on mixed fuel than on pure gasoline as the machine develops a gradual increase in mechanical torque and power as the proportion of ethanol in the fuel-mix and the rotational speed increases. While the highest values of torque and power developed on using pure gasoline are 12.4Nm and 2574W respectively at 1900rpm, 13.1Nm torque and 2953W power are obtained from the machine when powered with 10%-bioethanol fuel-mix at the same speed. Also, with 90V excitation voltage and rotation at 1500rpm synchronous speed, the driven machine continuously generates electricity at 207.6Vrms (line-to-line), 1.169A, 0.698pf, 48.17Hz, 0.294kW output. Therefore, this investigation shows that the availability of cocoa and kola nut harvest wastes could be explored as a steady source of biofuel for off-grid microgrid electrification at locations with such agricultural wastes advantages.

The influence of eddy currents on the excitation winding impedance of solid and laminated salient pole synchronous machines

This work investigates the establishment of steady-state eddy currents in solid and laminated salient poles and rotor rim of synchronous machines due to a periodic excitation voltage. It shows that the presence of eddy currents in the rotor magnetic circuit has the double effect of increasing the excitation winding AC-resistance and decreasing its magnetizing AC-inductance. According to that a simple analytical model is presented in here which allows a rapid rough estimation of the excitation winding AC-resistance when little information is available about the machine geometry and its electric/magnetic materials properties. The model is then verified by reproducing in frequency the excitation winding AC-resistance and the related power loss measured in two synchronous generators. Finally, the limits of reliability and applicability of the model are discussed. The model has implications for periodic field winding current control and voltage regulation in synchronous machines.

A Simple Flux-Based Technique to Specify the Faulty Pole of the Salient Pole Synchronous Machines

A portable flux probe is proposed and investigated in this article to detect turn-to-turn fault in the rotor poles of the high rated salient pole synchronous machines. The rotor circuit is fed by a low amplitude sinusoidal voltage source with a fixed voltage amplitude which has a frequency more than a few hundred Hz to achieve the higher reaction of the shorted turns on the faulty pole, which results in a significant reduction of the magnetic flux in the air-gap. Numerous simulations and experimental tests are carried out to investigate the proposed probe and the related technique performance to specify the faulty pole versus the number of shorted turns, applied frequency and probable eccentricity in the rotor position. The obtained test results show that all stable turn to turn faults (weak or heavy ones) can be specified easily by applying a portable sinusoidal voltage source with the frequency in the range of more than a few hundred Hz. The experimental test results validate that the flux density can be reduced to about zero in the faulty pole face, even in the case of one shorted turn in the sample machine.