Axis Reactance Research Articles

Performance analysis of a permanent magnet synchronous motor with dual stator windings

This paper presents the modelling and performance analysis of a line-start three-phase interior permanent magnet synchronous motor (IPMSM) with dual stator windings. The machine has two sets of windings, main and auxiliary windings. The main winding is connected to the supply while the auxiliary is connected to a balanced capacitor. The dynamic model equations are derived in the d-q rotor reference frame using the concept of winding function theory. The machine input impedance was construed from the steady-state equations, where the effects of capacitance on the performance of the motor were studied. An improved torque was obtained when a suitable capacitance was connected to the auxiliary winding. A point of good performance was established by enhancing its direct axis reactance and the quadrature axis reactance which depend on the size of the capacitor. It is shown that thenew configuration has better performance characteristics when compared with those of the traditional configuration in terms of output power, torque density and efficiency.

Dynamic Performance of a Hybrid Synchronous Machine with Ultra-High XD/XQ Ratio

This paper presents a hybrid synchronous machine with ultra-high XD/XQ ratio. A conventional synchronous machine has two components of output power; the excitation and the reluctance component. The reluctance power which depends on the saliency ratio (XD/XQ ) is negligible when compared with the excitation component. A hybrid machine with variable XD/XQ ratio has the capability of raising the reluctance component of the power to infinity theoretically. The stator frame of the hybrid machine is stacked with two identical cylindrical cores (A, B) that are magnetically isolated. A hybridised rotor; salient cum cylindrical is used. There are two windings on the stator core stacks identifiable as the main and control windings respectively which are electrically isolated but magnetically coupled. The main windings are connected in series across the two stacks (A and B) and the terminals connected to the utility supply for motor operation while for generator, the terminals feed the load busbar. The control windings are transposed in passing from one stack to the other and terminated across a balanced adjustable capacitor bank. It is shown that the quadrature axis reactance (XQ) of the hybrid machine can be adjusted from zero to infinity (0<=XQ<=inf.) theoretically by varying the balanced adjustable capacitor bank. The reluctance component of the output power of the machine which depends on the reactance ratio (XD/XQ ) is also seen to theoretically increase to infinity. The reluctance power is shown to be twice the excitation power when the capacitor of 800uf is connected to the control winding. Depending on the value of the capacitive reactance, the reluctance power can be made even ten times the excitation power.

Virtual laboratory to conduct slip test of synchronous machine

The educational system is presently undergoing a substantial change to improve the teaching-learning process of all engineering domains. This includes the utilization of user-friendly simulation tools as part of the laboratory for an enhanced practical experience on a virtual platform. Owing to the advantages of virtual experimentation, engineering laboratories are now preferably integrated with suitable simulation tools. This paper deals with the integration of simulation tools with undergraduate courses of electrical machinery. For this purpose, a simulation model was developed to conduct the slip test on a three phase synchronous machine on a virtual platform using MATLAB or Simulink for the determination of direct axis reactance Xd and quadrature axis reactance Xq . From the test results, a close relationship between the calculated value of synchronous reactance and rated parameters of the machine is observed, showing the acceptability and suitability of conducted test for the integration of virtual platform with laboratory session. Concept of virtual laboratory may be extended to undergraduate course of electrical machinery during teaching-learning process.

Platform for the determination of transitory and subtransient direct axis reactance of the synchronous machines

Este artículo trata sobre el diseño e implementación de una plataforma por medio de sensores y de una tarjeta de adquisición de datos permite visualizar variables en tiempo real y obtener parámetros de las pruebas aplicadas a las máquinas síncronas en estado dinámico. En particular se utiliza en máquinas sincrónicas de polos lizos en las cuales, como estudio de caso, se realiza la prueba de apertura de cortocircuito trifásico y una prueba de cortocircuito repentino en los devanados del estator con el fin de calcular las reactancias de eje directo transitoria, sub-transitoria y de estado permanente. Se utilizan sensores de tensión y de corriente los cuales captan y llevan información a una tarjeta NI USB 6009 de la National Instruments que sirve de interfaz con el software de evaluación Labview® en el cual se realizan los cálculos y acciones de control y adquisición necesarias para realizar los cálculos. Se muestra los esquemas de control, diseño e implementación del módulo de trabajo, adicionalmente los algoritmos y pruebas de funcionamiento realizadas al prototipo.

Phase Displacement Characteristics of a Parallel Hybrid Excitation Brushless DC Generator

The article presents theoretical analyses and comprehensive simulations on the phase displacement characteristics of a parallel hybrid excitation brushless DC generator (HEBLDCG). The HEBLDCG, which consists of the permanent magnet (PM) machine part and flux modulation machine part, operates at the unity displacement factor due to the diode rectifier. The PM flux and wound field flux are coupled at load because the armature windings of two parts are in series connection. By the analysis of the armature reaction, the phase displacement between phase voltage and phase current of each part is revealed. It is further deduced that the phase relationship between two parts is determined by the saliency ratio and the “displacement characteristic current” which is defined as the ratio of the fundamental electromotive force at no-load and the d -axis reactance. Based on this, the mode division method from the view of power and loss balance is proposed. These comprehensive operation modes, indicated by the internal power flow, facilitate a constant output voltage and power of the HEBLDCG under variable loads and operation speeds. Finally, the experiments verify the analyses at the constant output voltage operation.

Electromagnetic–Mechanical Design of Synchronous Reluctance Rotors With Fine Features

This paper explores the tradeoff between the electromagnetic and mechanical performances with regard to the design of a synchronous reluctance machine rotor with fine features in the lamination profile—the analyzed machine consists of four rotor poles and its stator is equipped with single tooth coils. The change in the electromagnetic characteristics of the ${d}$ - and ${q}$ -axis reactances is explored for variation in radial and tangential rib widths and the impact of increased rib width on the saliency ratio of the machine. It is shown that the increased radial and tangential rib widths impair electromagnetic performance, with the tangential rib having the most pronounced effect on performance in this rotor design. The mechanical performance of the design is also explored in a similar manner, where it is shown that the high stress concentration in the rotor radial and tangential ribs limits the maximum speed of the machine in the field weakening region. The radial rib is found to have the dominant impact on supporting the flux guides. It is shown that the prototyped machine can achieve good electromagnetic performance while maintaining mechanical integrity up to a 25% overspeed of 10 000 r/min with features as small as 0.3 mm. Additionally, the challenges associated with manufacturing, selecting a higher rotor pole number, and the possibility of mechanical failure are also discussed in the context of electromagnetic–mechanical design of such rotors, with important avenues of further research suggested.

Steady – State Performance of Induction and Transfer Field Motors – A Comparison

This paper presents the steady–state performance comparison between polyphase induction motor and polyphase TF motor operating in the asynchronous mode. It is shown graphically that a p-pole TF motor in operation is similar to an induction motor with 2p poles and hence its synchronous speed is limited to one-half (ω/2) of that of an induction motor. Additionally the pull-out torque of TF motor is inferior to that of an induction motor of the same dimensions, being less than ¼ of that of an equivalent induction motor on account of its higher leakage reqactance and in particular, the quadrature axis reactance. http://dx.doi.org/10.4314/njt.v34i2.24

Investigation of V-Shaped Line Start Permanent Magnet Motors Based on Reactance Effect

This paper presents an investigation into the effect of the reactance on a V-shaped line start permanent magnet motor. Five rotor designs with different V-shaped angles are utilized for exploring motor characteristics with the reactance. Performances such as back electromotive force, $d$ - and $q$ -axis reactance, loading capability and efficiency are simulated and analyzed by the torque model and a time stepped two-dimensional finite element software application. According to the comparison, the variations of output behaviors with $d$ - and $q$ -axis reactance can be described. Moreover, the design which features both excellent synchronization capability and high efficiency was verified by experiment on a prototype.

AC/DC Permanent Magnet Synchronous Generator Design and Research

This paper has designed and produced an ac/dc permanent magnet synchronous generator which used in ac/dc power system independent. The design of the motor and the basic properties of the motor is discussed in this paper. In order to reduce the voltage regulation of the permanent magnet generator, installation of a soft magnetic material in the generator permanent magnetic pole tail, by increasing the motor load quadrature axis reactance drop improves motor voltage regulation. A prototype is made and test analysis, the generator voltage regulation rate of small, high efficiency, and the simulation result is consistent with the basic design to achieve the requirements.

Measurement of synchronous machine parameters using Kalman filter based fuzzy logic estimator

This paper presents a new Kalman filter/fuzzy logic approach for estimating synchronous machine parameters from short circuit tests. The technique uses on-line noisy measurements of the short circuit current for estimating direct axis reactances, and time constant synchronous machine parameters. The approach is based on expressing short circuit current as a discrete time linear dynamic system model suitable for the Kalman filter to estimate the parameters. Fuzzy rule-based logic is used to tune-up measurement noise levels by adjusting the covariance matrix. The results show a better convergence using fuzzy logic than those solely using the Kalman filter.

Steady-state performance of a line-start synchronous reluctance motor with capacitive assistance

This paper sets forth the steady-state performance analysis of a connection scheme that improves the power factor and torque with a lower magnetizing current for a line-start synchronous reluctance motor. The machine stator winding is split into two equal halves, one connected to the mains and the other connected to a balanced capacitor. Performance of the machine is improved if the capacitor value is such that the winding to which it connected operate at or very close to resonance in the d-axis. Current in both windings contributes positively to torque production and external control circuitry is not required. Steady-state equations arising from the d– q model gives a direct insight on the operating limits and how this capacitance aids the machines torque and power factor by boosting its direct axis reactance while the quadrature axis reactance remains fairly constant. An equivalent circuit is also deduced from the steady-state equations from which an explicit expression for input impedance of the new machine can be derived. Conditions for unity-power factor at varying load conditions are also examined. A comparison with conventional single-winding synchronous reluctance motor is given. Such comparison is fair because both machines have the same amount of copper and iron. Experimental results are provided to validate the analytical results.

The Performance Research of Starter-Generator Based on Reluctance Torque Used in HEV

The objective of this paper is to describe the role that reluctance plays in interior permanent magnet (IPM) starter-generator (SG) analytically. 4-pole and 6-pole models of SG including the radial and tangential flux are analyzed. For increasing the value of q -axis reactance, several possible factors are considered. The stationary torque versus control angle was predicted by finite element analysis (FEA). The permanent magnet and the reluctance components of the torque were analyzed and computed. The results show that the rotor shape, magnet length, magnet thickness and the amount of poles etc., will observably affect the component of the reluctance. One working prototype of the SG-1 was built and fully tested. The motoring torque within 1700 rpm and the generating power within 6000 rpm were measured. The motoring power can supply 8 kW at 1700 rpm and the torque can keep constantly with 45 Nm; Generating results have proven that the ISG is capable of meeting the specification for output power 4 kW up to 6000 rpm and the maximal speed can reach to 7927 rpm. In addition, the efficiency contour maps of motoring and generating are obtained by experiment. The results show that the prototype has wide high efficiency region. The FEA prediction and experiment results were proved well. The improved prototype SG-2 was simulated by FEA. SG-2 is a radial-flux structure machine, and its utilization of permanent magnet and the saliency ratio are both higher than SG-1. The results show that no matter constant torque ability or the constant power range, compared with SG-1, SG-2 both has an improvement to a large extent.

Field Circuit Coupling Optimization Design of the Main Electromagnetic Parameters of Permanent Magnet Synchronous Motor

The electromagnetic parameters of a permanent magnet synchronous motor (PMSM) such as the open load permanent magnet flux, d axis reactance <TEX>$X_d$</TEX>, and q axis reactance <TEX>$X_q$</TEX>, are most essential to the performance analysis and optimization design of the motor. Based on the numerical analysis of the 3D electromagnetic field, the three electromagnetic parameters of permanent magnet synchronous motors with U form interior rotor structures are calculated by FEA. The rules of the leakage coefficient and reactance parameters changing with the air gap length, permanent magnet magnetism length, and isolation magnetic bridge dimensions in the rotor are given. The calculated values agree well with the measured values. The FEA results are integrated with the self compiled electromagnetic design program to optimize the prototype motor. The tested performances of the prototype motor prove that the method is suitable for the optimization of motor structure.

Genetic-based algorithm for identification of synchronous machine parameters using short-circuit tests

In this paper a new method for the digital identification of synchronous machine parameters from short-circuit tests is presented. The method is based on the genetic algorithm optimization technique. Genetic algorithms (GAs) are adaptive search procedures based on the mechanism of natural selection and genetics. This kind of algorithm can search for a global solution using multiple paths. The proposed method uses a digital set of measurements for the short-circuit current for estimating direct axis reactance and time constant. A set of over-determined system of equations is constructed using the digital current samples. The identification problem is then solved using the proposed GAs-based method. Different fitness functions that evaluate the solutions are suggested. A practical case study is presented in this work to evaluate the proposed method. Results are reported and conclusions are drawn. Copyright © 2000 John Wiley & Sons, Ltd.

A comparison between two-axis and 3D finite element theory for AC side excited machines

Two methods for the calculation of load conditions in AC side excited homopolar machines are compared. First a 3D finite element technique is used directly, secondly the finite element method is used to calculate axis reactances for use in the two-axis method. The work is validated by experimental results.

Predicting the performance of a permanent magnet synchronous motor by analytical and numerical methods

The performance of a permanent magnet (PM) motor is predicted by using both analytical and numerical methods. From the simple analytical calculations, the initial machine dimensions for more accurate numerical analysis can be obtained easily. The resulting expressions can also be used for calculating different machine parameters, such as direct and quadrature axis reactances or generated voltage. The numerical calculations are performed by the finite element method. The field equation and the circuit equations of the winding are combined and solved together. By utilizing the procedure presented, the performance of a designed PM motor can be predicted with good accuracy. >

Power capability of salient pole permanent magnet synchronous motors in variable speed drive applications

A constant-parameter equivalent circuit model that neglects motor losses is used to determine the effects of direct and quadrature reactances and open-circuit voltage on the power capability of salient-pole permanent-magnet motors in variable-speed drive applications. It is shown that peak power capability over a range of speeds can be obtained by proper control of the magnitude and phase of the armature current. Due to the voltage constraint imposed at the motor terminals, the power capability will fall to zero for most motor designs at a given high speed. A simple relationship between the motor open-circuit voltage and the direct axis reactance is derived to obtain motor designs that, even with this voltage constraint in place, extend their theoretical power capability, neglecting losses, to infinite speed. All results are presented in normalized curves using a per-unit system.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A finite element technique for calculating the magnet sizes and inductances of permanent magnet machines

A method for calculating the magnet size, and the direct and quadrature axis reactances of permanent magnet synchronous machines, using the finite-element method is presented. In this method the machine is modeled by its equivalent d-q representation of armature MMF and the appropriate reactances are calculated from the magnetic energy in the magnetic field. This is in contrast to the conventional approach of using an abc phase current model, solving the model and then converting the resulting quantities to respective d-q-o quantities. The method is applied to a permanent magnet motor design.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Analytical models for interior-type permanent magnet synchronous motors

Keen interest in the design of Permanent Magnet (P.M.) synchronous motors is being fuelled by continuing developments in permanent magnet material technology. The most recent of these developments has been in the introduction of Neodymium-Boron-Iron (N <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</inf> BF <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">e</inf> ) with residual flux density of 1.23 T and energy product (BH <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</inf> ) of 320 kJ/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . However a continuing difficulty with the analysis of permanent magnet motors, irrespective of their magnet composition, is the prediction of the direct and quadrature axis reactances. This is particularly the case with motors having permanent magnets imbedded in the rotor iron below the cage winding. The purpose of this paper is to present equivalent circuit models for such interior-type P.M. motors and develop simple analytical expressions for the calculation of axis reactances. Computed reactances including saturation effects are presented along with experimental values for verification.

Iron saturation effects in PM AC motors

Iron saturation causes the lumped circuit parameters to vary with the point of operation. Experimental evidence shows that the field excitation voltage and the direct axis reactance are not affected significantly by the armature reaction. This can be attributed to the presence in the direct axis of the magnets whose thickness represents a large effective air gap. In the quadrature axis, instead, the contribution of the air gap to the reluctance is small. Therefore, the quadrature axis reactance depends strongly on both the quadrature and direct axis components of armature magnetomotive force. This suggests a simple, albeit approximate, approach for predicting the parameter variation with operating point. As a result, both the design and analysis of synchronous motors excited by permanent magnets (PM's) are facilitated.