Induction Electrical Machines Research Articles

Dynamics parameters estimation of an asynchronous machine plus mechanical shaft set through orbit frequency response analysis

This paper presents some of the results obtained upon the experimental study of the behaviour of a prototype mechanical shaft driven by an induction electric machine. The main focus of this paper will be on the mechanical response of the set, based on the measurement of a number of mechanical variables and its integration in well-known mechanical models, allowing a more accurate estimation of the actual parameters of the prototype machine. The results thus obtained can then be used to test the theoretical models, estimate mechanical parameters more accurately and generally increase knowledge on the mechanical response of the prototype set.

Analytical study of air-gap surface force – application to electrical machines

AbstractThe Maxwell stress tensor (MST) method is commonly used to accurately compute the global efforts, such as electromagnetic torque ripple and unbalanced electromagnetic forces in electrical machines. The MST has been extended to the estimation of local magnetic surface force for the vibroacoustic design of electrical machines under electromagnetic excitation. In particular, one common air-gap surface force (AGSF) method based on MST is to compute magnetic surface forces on a cylindrical shell in the air gap. However, the AGSF distribution depends on the radius of the cylindrical shell. The main contribution of this study is to demonstrate an analytic transfer law of the AGSF between the air gap and the stator bore radius. It allows us to quantify the error between the magnetic surface force calculated in the middle of the air gap and the magnetic force computed on the stator teeth. This study shows the strong influence of the transfer law on the computed tangential surface force distribution through numerical applications with induction and synchronous electrical machines. Finally, the surface force density at stator bore radius is more accurately estimated when applying the new transfer law on the AGSF.

Метод ідентифікації моделей оптимального руху електромобіля з асинхронним електроприводом

There has been proposed the method of motion models identification of an electric car with a traction induction motor by horizontal road segment, optimal by the criterion of the minimum of electric losses, synthesized using a mathematical model of the magnetization curve in the form of an inverted hyperbolic sine, which with high precision binds the current in the stator winding of an induction motor with a magnetic flux created by the field of this current and therefore corresponds to the physical conditions of the actual operation of induction electric machines, and using Lagrange variational method option that leads to the field extremals in coordinates relative time, relative speed and relative electric current in the drive motor's stator winding. At the first stage of implementation of the proposed method of motion models identification of an electric car with a traction induction drive, the constants that occur in these models due to the use of two integration operations in the process of their synthesis are determined. In the second stage of implementation, we propose a direct algorithm for determining the velocity of an electric car based on its dynamics model, and in the third stage, synthesized an iterative algorithm for determining the current associated with the velocity of an electric car by the ratio obtained as a result of solving the optimization problem by the method of indefinite Lagrange multipliers. The defined conditions that are imposed on the iterative process of optimal current model identification are determined, supplied from an electric car battery through the DC to AC converter in the traction induction motor stator winding and the conditions which must satisfy the process of determining the moments of time at which the identification process of this model is carried out, on which the accuracy of determining the electric car optimal movement trajectory coordinates depends

Design tools for electromagnetic-driven multi-physics systems using high performance computing

Purpose The design of electromagnetic systems for a variety of applications such as induction heating, electrical machines, actuators and transformers requires the solution of a multi-physics problem often involving thermal, structural and mechanical coupling to the electromagnetic system. This results in a complex analysis system embedded within an optimization process. The appearance of high-performance computing systems over the past few years has made coupled simulations feasible for the design engineer. When coupled with surrogate modelling techniques, it is possible to significantly reduce the wall clock time for generating a complete design while including the impact of the multi-physics performance on the device. Design/methodology/approach An architecture is proposed for linking multiple singe physics analysis tools through the material models and a controller which schedules the execution of the various software tools. The combination of tools is implemented on a series of computational nodes operating in parallel and creating a “super node” cluster within a collection of interconnected processors. Findings The proposed architecture and job scheduling system can allow a parallel exploration of the design space for a device. Originality/value The originality of the work derives from the organization of the parallel computing system into a series of “super nodes” and the creation of a materials database suitable for multi-physics interactions.

Control Strategy to Start a Shaft Generator System Employing DFIM Under Power Take Me Home Mode

Comparing to the traditional synchronous or induction electric machines, the doubly-fed induction machine (DFIM) with the partially rated converter is a good solution for a shaft generator system which normally operates within a relatively small adjustable speed range. However, the application of DFIM is limited in the real systems due to the lack of self-start capability under the power take me home (PTH) mode when the main engine fails. To overcome this problem, an approach is proposed in this paper. The basic idea is first to start the machine in the induction machine (IM) mode feeding from the ship-borne power grid (SPG) and then to switch over into the DFIM mode when the speed reaches its normal speed range. The hardware scheme, start procedure and control algorithm of the start approach are presented in the paper. Simulation and experimental studies were carried out to validate the feasibility and effectiveness of the approach.

A Dynamic Model of Induction Machine

In this paper, we study the construction, the equations and parameters of induction electrical machines, and also particularities of dynamic properties.

Dynamic Model of Induction Machine

In this paper, we study the construction, the equations and parameters of induction electrical machines, and also particularities of dynamic properties.

Regenerative energy management of electric drive based on Lyapunov stability theorem

In recent years, urban rail systems have developed drastically. In these systems, when induction electrical machine suddenly brakes, a great package of energy is produced. This package of energy can be stored in energy storage devices such as battery, ultra-capacitor and flywheel. In this paper, an electrical topology is proposed to absorb regenerative braking energy and to store it in ultra-capacitor and battery. Ultra-capacitor can to deliver the stored energy to DC grid and to charge the battery for auxiliary applications such as lighting and cooling systems. The proposed system is modeled based on large signal averaged modeling, which leads to the simplicity of calculations. The control system is based on Lyapunov stability theorem which guarantees system stability. Also, an energy management algorithm is proposed to control energy under braking and steady-state conditions. Finally, the simulation results validate the effectiveness of the proposed control and energy management system.

System Modeling and Simulation of In-Stream Hydrokinetic Turbines for Power Management and Control

Electricity generation from moving currents without using dams (i.e., in-stream hydrokinetic electricity) has the potential to introduce multiple GW of renewable power to U.S. grids. This study evaluates a control system designed to regulate the generator rotor rate (rpm) to improve power production from in-stream hydrokinetic turbines. The control algorithm is evaluated using numerical models of both a rigidly mounted tidal turbine (TT) and a moored ocean current turbine (OCT) coupled to an induction electric machine model. The moored simulation utilizes an innovative approach for coupling a multiple degrees-of-freedom (DOF) nonlinear hydrodynamic/mechanical turbine model with a nonlinear electromechanical generator model. Based on the turbine torque-speed characteristic, as well as the asynchronous machine features, a proportional–integral (PI) controller is used to generate a correction term for the frequency of the three-phase sinusoidal voltages that are supplied to the asynchronous generator. The speed control of the induction generator through the supply frequency is accomplished by a simplified voltage source inverter (VSI). The simplified VSI consists of control voltage sources (CVSs), while the comparison with a real VSI using diodes and transistors, which are controlled by pulse width modulation (PWM) technique, is also presented. Simulations are used to evaluate the developed algorithms showing that rpm fluctuations are around 0.02 for a tidal turbine operating in a wave field with a 6 m significant wave height and around 0.005 for a moored ocean current turbine operating in a wave field with a 2 m significant wave height.

Electromagnetic Modeling and Analysis of Can Effect of a Canned Induction Electrical Machine

The can shields in airgap characterize a canned electrical machine as a hydraulic pump drive. This paper studies modeling and characterization of the can effect. To analyze electromagnetic field on can shields, followed by can loss, an analytical model is proposed. Such a model is of concentric cylindrical rotor layer structure with the slotting effect and magnetic saturation. This work is performed by comparing an ordinary induction machine with a canned version. Based on differences of airgap flux distribution, iron loss due to the can effect is analyzed. Then, the can loss and harmonics under typical operating condition are analyzed. The can loss calculation determined by magnetic saturation is discussed. Finite element method and measurement are used as reference.

Modeling and design of cooperative braking in electric and hybrid vehicles using induction machine and hydraulic brake

In mixed-mode braking applications, the electric motor / generator (M/G) and hydraulic pressure valve are controlled to meet the driver’s braking demand. Controlling these braking elements is achieved by modulating the current generated by the M/G and adjusting the fluid pressure to the wheel brake cylinders. This paper aims to model and design combined regenerative and hydraulic braking systems which, comprise an induction electric machine, inverter, NiMH battery, controller, a pressure source, pressure control unit, and brake calipers. A 15 kW 1500 rpm induction machine equipped with a reduction gear having a gear ratio of 4 is used. A hydraulic brake capable to produce fluid pressure up to 40 bar is used. Direct torque control and pressure control are chosen as the control criteria in the M/G and the hydraulic solenoid valve. The braking demands for the system are derived from the Federal Testing Procedure (FTP) drive cycle. Two simulation models have been developed in Matlab®/Simulink® to analyze the performance of the control strategy in each braking system. The developed model is validated through experiment. It is concluded that the control system does introduce torque ripple and pressure oscillation in the braking system, but these effects do not affect vehicle braking performance due to the high frequency nature of pressure fluctuation and the damping effect of the vehicle inertia. Moreover, experiment results prove the effectiveness of the developed model.

Dynamic Equivalent Method of Motor Loads for Power Systems Based on the Weighted

Dynamic equivalence can not only largely reduce the system size and the computation time but also stress the dominant features of the system [1]-[3]. This paper firstly recommends the basic concept of dynamic equivalent and the status of both domestic and abroad development in this area. The most existing equivalent methods usually only deal with static load models and neglect the dynamic characteristics of loads such as induction motors. In addition, the existing polymerization method which is based on the frequency domain algorithm of induction electric machines parameters takes a long time to equivalent for the large system, then the new method based on the weighted is proposed. Then, the basic steps for dynamic equivalence with the weighted method are introduced as follows. At first, the clustering criterion of motor loads based on time domain simulation is given. The motors with similar dynamic characteristics are classified into one group. Then, the simplication of the buses of motors in same group and network is carried out. Finally, parameters of the equivalent motor are calculated and the equivalent system is thus obtained based on the weighted. This aggregation method is applied to the simple distribution system of 4 generators. Simulation results show that the method can quickly obtain polymerization parameters of generator groups and the aggregation model retains the dynamic performance of the original model with good accuracy, the active and reactive power fitting error is smaller as well.

Feature Extraction for the Prognosis of Electromechanical Faults in Electrical Machines through the DWT

Recognition of characteristic patterns is proposed in this paper in order to diagnose the presence of electromechanical faults in induction electrical machines. Two common faults are considered; broken rotor bars and mixed eccentricities. The presence of these faults leads to the appearance of frequency components following a very characteristic evolution during the startup transient. The identification and extraction of these characteristic patterns through the Discrete Wavelet Transform (DWT) have been proven to be a reliable methodology for diagnosing the presence of these faults, showing certain advantages in comparison with the classical FFT analysis of the steady-state current. In the paper, a compilation of healthy and faulty cases are presented; they confirm the validity of the approach for the correct diagnosis of a wide range of electromechanical faults.

Transient detection of eccentricity-related components in induction motors through the Hilbert–Huang Transform

The identification and extraction of characteristic patterns are proposed in this work for the diagnosis and evaluation of mixed eccentricities in induction electrical machines with parallel stator branches. Whereas the classical diagnosis approaches, deeply spread in the industrial environment, are based on the Fourier analysis of the steady-state current, the basis of the proposed methodology consist of analysing the current demanded by the machine during the connection process (startup transient); the objective is to extract the characteristic evolution during the transient of some harmonic components created by the fault; this evolution is caused by the dependence of these components on the slip ( s), a quantity varying during the startup transient from 1 to almost 0. For this feature extraction, the Hilbert–Huang Transform (HHT) is proposed. An analysis of the behaviour of this transform in comparison with another time-frequency approach used in other works, the Discrete Wavelet Transform (DWT), is also presented in the paper. The results show the usefulness of the methodology for the reliable diagnosis of the mixed eccentricity fault and for the correct discrimination against other types of failures.

Feature Extraction for the Prognosis of Electromechanical Faults in Electrical Machines through the DWT

Recognition of characteristic patterns is proposed in this paper in order to diagnose the presence of electromechanical faults in induction electrical machines. Two common faults are considered; broken rotor bars and mixed eccentricities. The presence of these faults leads to the appearance of frequency components following a very characteristic evolution during the startup transient. The identification and extraction of these characteristic patterns through the Discrete Wavelet Transform (DWT) have been proven to be a reliable methodology for diagnosing the presence of these faults, showing certain advantages in comparison with the classical FFT analysis of the steady-state current. In the paper, a compilation of healthy and faulty cases are presented; they confirm the validity of the approach for the correct diagnosis of a wide range of electromechanical faults.

A built-in force actuator for active control of lateral rotor vibration in cage induction electrical machines

In this paper means of active control of radial rotor vibrations in electrical machines are considered. We examine a built-in force actuator for active generation of force on the machine rotor. The operation of the actuator is based on electromechanical interaction between the rotor and the stator of the machine. The actuator is given a low-order linear state-space model, which is identified by using simulation data obtained from a detailed time-stepping finite element model of the machine. Simulation results obtained by using real machine data and finite element time-stepping method are presented.

Improved Cooling in the End Region of a Strip-Wound Totally Enclosed Fan-Cooled Induction Electric Machine

Computational fluid-dynamics modeling has been used to investigate the cooling of the end region of a two-pole strip-wound totally enclosed fan-cooled induction motor. The modeling is validated by experimental measurements. The changes in airflow and heat transfer that each configuration gives are discussed, and recommendations are made of features that can be used to achieve lower convective thermal resistance in the end region.

A model-based flexural rotor vibration control in cage induction electrical machines by a built-in force actuator

In this paper active control of flexural rotor vibration in electrical machines is examined. We consider attenuation of discrete low-frequency range forced vibration components by means of an adaptive harmonic control strategy. A built-in force actuator for actively generating force on the machine rotor is investigated. Previously, such an actuator has mainly been used in bearingless machine design for rotor levitation. The action of the actuator is based on electromechanical interaction between the rotor and the stator of the machine. A low-order linear parametric state-space model is derived for the actuator–rotor system. Parameter estimation is carried out using simulation data obtained from a detailed two-dimensional time-stepping finite element field-circuit model of the machine. Hence, model-based control design is performed using the identified model. The controller is verified by embedding it into the finite element analysis. As a result we present a virtual plant of the machine with vibration control. The virtual plant is introduced as a means of vibration control design prior to implementing the control algorithms in a real machine. Simulation results using real machine data and finite element time-stepping method are presented.

A model-based flexural rotor vibration control in cage induction electrical machines by a built-in force actuator

A model-based flexural rotor vibration control in cage induction electrical machines by a built-in force actuator

Calculation of some basic flux quantities in induction and other doubly-slotted electrical machines

The distribution of magnetic flux in the air gap of an electric machine is of fundamental importance in determining such quantities as stray losses, torque, reactances and magnetic noise. The author discusses some of the methods of approach which have been employed in the determination of the basic flux quantities in induction and other doubly slotted machines. By a new form of analytical approach, equations are obtained for some important quantities; these include accurate, but simple, equations for gap permeance and the amplitude of certain flux pulsations. Also developed are some basic equations for air-gap leakage flux, including its variation with rotor movement. Tests made on models in an electric-tank analogue confirm the equations obtained for this component of leakage flux and give some additional information regarding flux pulsations.