Model Of Induction Machine Research Articles

An extended winding function model for induction machine modelling considering saturation effect

An extended winding function model for induction machine modelling considering saturation effect

An Adaptive Identification of Rotor Time Constant for Speed-Sensorless Induction Motor Drives: A Case Study for Six-Phase Induction Machine

Accurate rotor time constant ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$T_{r}$ </tex-math></inline-formula> ) value is necessary to ensure an acceptable performance of the indirect field-oriented control (IFOC) strategy, where a detuned <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$T_{r}$ </tex-math></inline-formula> affects rotor flux orientation and, in turn, results in poor dynamic and steady-state response of torque. The problems associated with detuned <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$T_{r}$ </tex-math></inline-formula> will be exacerbated in sensorless drives when a model-based speed estimation algorithm is employed. This article investigates the problem of simultaneous identification of the rotor time constant and rotor speed for sensorless IFOC of six-phase induction motor (6PIM) drives. First, an adaptive observer is proposed for online detection of the low-frequency sinusoidal signal, which is intentionally injected into the rotor flux command. Then, a novel model reference adaptive system (MRAS)-based <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$T_{r}$ </tex-math></inline-formula> estimator is proposed using the detected signal. The Lyapunov stability theorem is used to ensure the asymptotic stability of the proposed identification system. The proposed method is based on the induction machine (IM) model in primary subspace, i.e., <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\alpha $ </tex-math></inline-formula> – <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> subspace. Hence, it is usable for other multiphase IM (three phases and higher). Nevertheless, the 6PIM is adopted here as a case study. The simulation and experimental results clarify the effectiveness of the proposed parallel estimation system.

Saturated VSD model of a six‐phase induction machine

In this study, a saturated model of an asymmetrical six-phase induction machine is presented. The model is based on the vector space decomposition approach, and it includes main and leakage flux saturation, as well as the mutual coupling between orthogonal planes while using the Gamma equivalent circuit approach. The accuracy of the proposed model in unbalanced operating modes that are characteristic for multiphase machines, such as post-fault and power-sharing operation, makes it advantageous compared to existing models. The model is developed assuming that the machine operates in asymmetrical conditions and that, therefore, there is fundamental frequency excitation in both planes. The inter-plane coupling effect is examined using finite element analysis and an experimental procedure for its quantification is developed. The model is verified by comparison with the experimental results obtained from a prototype asymmetrical six-phase induction machine, and its advantages compared to existing models are emphasised.

Modeling and control of double star induction machine by active disturbance rejection control

This paper aims to contribute to the modeling and control of the double star induction machine (DSIM) by a robust method called active disturbance rejection control (ADRC). The ADRC has become in the last decade one of the most important techniques of regulation. This method is based on the use of an ESO (Extended State Observer) which estimates in real-time and at the same time the external disturbances and the errors due to the variations of the parameters of the machine and to the uncertainties of modeling. The two stators of DSIM are powered by three-phase inverters based on transistors and MLI control and the entire system is modeled in Park's reference. We analyze in the Matlab/Simulink environment the dynamic behavior of the system and the different ADRC controllers under different operating conditions. The result has demonstrated the performance and effectiveness of the ADRC.

Modeling of a Quasi-Resonant DC Link Inverter Dedicated to Common-Mode Voltage and Ground Current Reduction

In this paper, the modeling methodology of the AC drive system with a Parallel Quasi-Resonant DC Link Inverter (PQRDCLI) is described. A presented modeling approach is an attractive tool used for the effective evaluation of a common-mode (CM) voltage and grounds current reduction methods. Designed models of inverter, induction machine (IM), and cable are simple, thus the methods for parameter extraction are not complicated. Verification of the proposed modeling approach was realized with the use of the the Synopsys (Mountain View, CA, USA) SABER simulator, while simulation results were experimentally verified. Operation principles of the proposed PQRDCLI converter topology are also described. Based on simulation and experimental results, it was confirmed that the proposed PQRDCLI solution represents required performance within the reduction of common-mode voltage and ground current in electric drives. Moreover, comparisons from a simulation complexity point of view have been performed to the existing methods. The evaluation is being shown at the end of the paper. It is confirmed that the presented method is simple, fast, accurate, and robust as well.

Model reduction based on sparse identification techniques for induction machines: Towards the real time and accuracy-guaranteed simulation of faulty induction machines

The development of condition monitoring (CM) systems of induction machines (IMs) is essential for the industry because the early fault detection would help engineers to optimise maintenance plans. However, the use of several IMs to test and validate the fault diagnosis methods developed requires also costly test benches that, anyway, often face limitations in the range of faults and operating conditions to be tested. To avoid it, the use of accurate models such as those based on finite element method (FEM) would reduce the major drawbacks of test benches but their inability to execute FEM models in real time largely reduces their application in the development of on-line continuous monitoring systems. To alleviate this problem a hybrid FEM-analytical model has been proposed. It uses an analytical model that can be run in real-time in a hardware in the loop (HIL) system, after its parameters have been computed through FEM simulations. In this way, the proposed model provides high accuracy but at the cost of long simulation times and high computational costs (both computing power and memory resources) to compute the IM parameters. This work aims at reducing these drawbacks. In particular, a model based on sparse identification techniques is proposed. The method balances complexity and accuracy by selecting a sparse model that reduces the number of FEM simulations to accurately compute the coupling parameters of an IM model with different fault severity degrees. Particularly, the proposed methodology has been applied to develop models with abnormal eccentricity levels as this fault is related to development of mechanical faults that produce most of IM breakdowns.

Accounting for Magnetic Saturation Effects in Complex Multi-harmonic Model of Induction Machine

Computations of quasi-dynamic electromagnetic field of induction machines using the complex magnetic vector potential require the use of the so-called effective magnetization curves, i.e., such in which the magnetic permeability is proportional to the amplitudes of magnetic flux density B or magnetic field strength H, not their instantaneous values. There are several definitions of that parameter mentioned in the literature provided for the case when B or H are monoharmonic. In this paper, seven different methods of determining the effective magnetization curves are compared in relation to the use of a field-circuit multi-harmonic model of an induction machine. The accuracy of each method was assessed by computing the performance characteristics of a solid-rotor induction machine. One new definition of the effective permeability was also introduced, being a function of multiple variables dependent on amplitudes of all the harmonics considered. The analyses demonstrated that the best practical approach, even for the multi-harmonic case, is to express the effective magnetic permeability as the ratio of the amplitudes of the fundamental harmonics of the magnetic flux density and the magnetic field strength, and assuming the sinusoidal variation of the latter.

Efficient Approach Based on Equivalent Electric Circuit Model to Determine Rotor Bar Currents of Squirrel Cage Induction Machines

Nowadays, finite element method is the most accurate approach to study an electrical machine. However, its use in an optimization process remains often unsuitable because it can still require prohibitive calculation times. An analytical approach would then be more adapted but it should be as accurate as possible. In the case of an analytical model of a squirrel cage induction machine, currents induced in the rotor bars constitute quantities that are difficult to obtain. The equivalent electrical circuit to use should be well adapted and each of its elements has to be accurately estimated. In this article, an equivalent circuit based on bar lumped parameters is proposed and their identification is detailed. The proposed approach is validated through the comparisons of simulation results with the ones obtained by classical FEA in the case of two examples of squirrel cage induction machines with distributed and concentrated armature windings.

A New Stability Index for Induction Motors Three-Phase Fault Recovery in Industrial Networks Based on Post-Fault Slip Estimation

In the present paper, an attempt has been made to introduce a new Stability Index (SI) for induction motors (IMs) three-phase fault recovery in industrial networks. The proposed SI is based on the steady-state model of induction machine as well as the usage of concepts related to stable and unstable equilibrium points. This index is evaluated by estimating the post-fault slip and is a function of the maximum slip and slips related to the induction motor operating point in pre-fault and post-fault torque-slip characteristics. Moreover, this index quantifies the amount of stability in addition to the stability state determination. The method is validated through comparison between the analytical and dynamic simulation results. Sensitivity analysis has also been used to describe the proposed index completely. This paper also presents a novel objective function by which the fault recovery process can be done optimally. The proposed method presented in this paper has also been applied to two industrial networks, one of which is the modified IEEE 9-bus system.

Estimation of inverter voltage disturbances for induction machine drive using LPV observer with convex optimization

This paper presents a Linear Parameter-Varying (LPV) observer for an Induction Machine (IM) under sinusoidal DC-supply disturbances. The observer estimates not only the IM state variables, but also the disturbances considered as a part of the states. As the extended IM model depends on the stator angular speed ωs and the rotor angular speed ωr, the proposed observer is designed by convex optimization to induce a convergence of the observer for a predetermined range of ωs and ωr. The estimated disturbances can be used to compensate for the real disturbances. The simulation results show the effectiveness of the observer, and experimental results on a laboratory test-bench have been obtained. The proposed method can be extended to other type of motor drives.

Optimization Procedure for Computing Sampling Time for Induction Machine Parameter Estimation

This paper presents a method for selecting the sampling time for induction machine parameter estimation from the machine line start measurements. the metaheuristic optimization method is used to find the optimal Prony exponential series approxiamtion of the line start transient current. From the optimal approximation, poles of the linearized induction machine model are computed and used to determine the optimal sampling time. the results show that sampling frequencies needed for parameter estimation are much lower than 1–15 kHz commonly used today. This reduces the necessary amount of collected data and the computing power needed for the estimation. the optimal sampling time is computed for the simulated and for the measured data. Referenced parameter estimation technique is tested for the measured transient showing benefits of using the optimal sampling time.

State space modeling theory of induction machines

Abstract The paper discusses the theoretical background of the state space modeling of induction machines. The main goal is to present the necessary equations of the induction machine and the topic of the state space modeling. Although the induction machine is a highly non-linear system, LPV/qLPV model can be formulated from these equations.

HDL Coder-based FPGA implementation of a continuous-discrete time observer for sensorless induction machine

ABSTRACTA continuous-discrete time high gain observer (CDHGO) for sensorless control of an induction machine (IM) is proposed in this paper. From only the two undersampled and noisy stator current measurements, an estimation of the IM states variables such as rotor flux, mechanical speed, and the load torque is achieved. Precisely, After a mild change of state coordinates that transform the IM model into the quasi-block triangular form, both observation stages are designed in a cascade structure. A hardware implementation of the CDHGO is carried out in the FPGA target by using advanced Matlab tools namely HDL Coder and Fixed Point Designer. Through the ModelSim software, a validation of the implemented algorithm is performed, where the estimates brings closer the those provided by the model despite the lack of information between the sample instants and the presence of the measurements noise.

An improved model of cage induction machines for fast transients studies

An improved model of cage induction machines for fast transients studies

Multi-Scale Induction Machine Model in the Phase Domain With Constant Inner Impedance

An efficient and accurate multi-scale induction machine model for simulating diverse transients in power systems is developed and validated. Voltages, currents, and flux linkages are described through analytic signals that consist of real in-phase and imaginary quadrature components, covering only positive frequencies of the Fourier spectrum. The stator is modeled in the abc phase coordinates of an arbitrary reference frame whose rotating speed is adjusted by a simulation parameter called shift frequency. When the reference frame is stationary at a zero shift frequency, then the model processes instantaneous signals to yield natural waveforms. When the reference frame is set to rotate at the synchronous frequency of the electric network, then the Fourier spectra of the analytic signals are shifted by this synchronous frequency to become dynamic phasors that allow for efficient envelope tracking. The shift frequency can be adapted during simulation. For any rotor position and independent of the variation of the magnetizing inductances with saturation, the induction machine model appears as a Norton current source with constant inner admittance in the abc phase domain to support the integration with simulators that represent the electric network in the abc phase domain. The analysis of test cases covering diverse transients substantiates the claims made in terms of accuracy and efficiency across different time scales.

A TDF Model in Induction Machines for Loose Bearing Diagnosis by Neutral Voltage

The bearing wear and looseness are significant failures in induction machines. For accurate recognition of the bearing faults, a new comprehensive modeling and analysis of induction machines with three degrees of freedom along with an effective method for loose bearing signature are presented in this article. For these purposes, the electromagnetic radial force and rotating torques are determined and applied to Euler–Lagrange equations of an induction machine. Besides, to better identify the defective loose bearings, the spectral analysis of neutral voltage is utilized. Comparing the experimental results with the outcome of the numerical analysis validates the proposed model. The results show that the spectral analysis of the neutral voltage detects mechanical looseness with higher precision than the conventional techniques such as mechanical vibrations and stator currents.

A Dynamic Model for Saturated Induction Machines With Closed Rotor Slots and Deep Bars

This paper deals with a dynamic model for three-phase induction machines equipped with closed rotor slots and deep rotor bars. The thin bridges closing the rotor slots saturate highly as a function of the rotor current. The impedance of the rotor bars also varies much as a function of the rotor current frequency. An extended dynamic model, which takes into account the slot-bridge saturation and the deep-bar effect, is developed. The model extensions can be plugged into a standard machine model and parametrized easily. The proposed model can be applied to time-domain simulations, real-time control, and identification. The model is validated by means of finite-element analysis and experiments using a four-pole 5.6-kW induction machine. The results show that the accuracy of the proposed model is superior to the standard model, particularly under transient excitation typically used in standstill self-commissioning tests of induction motor drives.

Induction machine model with space harmonics for the diagnosis of rotor eccentricity, based on the convolution theorem

Condition based maintenance (CBM) systems of induction machines (IMs) require fast and accurate models that can reproduce the fault related harmonics generated by different kinds of faults. Such models are needed to develop new diagnostic algorithms for detecting the faults at an early stage, to analyse the physical interactions between simultaneous faults of different types, or to train expert systems that can supervise and identify these faults in an autonomous way. To achieve these goals, these models must take into account the space harmonics of the air gap magnetomotive force (MMF) generated by the machine windings under fault conditions, due to the complex interactions between spatial and time harmonics in a faulty machine. One of the most common faults in induction machines is the rotor eccentricity, which can cause significant radial forces and, in extreme cases, produce destructive rotor-stator rub. However, the development of a fast, analytical model of the eccentric IM is a challenging task, due to the non-uniformity of the air gap. In this paper, a new method is proposed to obtain such a fast model. This method, which is theoretically justified, first enables a fast calculation of the self and mutual inductances of the stator and rotor phases for every rotor position, taking into account the non-uniform air-gap length and the actual position of all the stator and rotor conductors. Once these inductances are calculated, they are used in a coupled circuits analytical model of the IM, which in this way is able to calculate the time evolution of the electrical and mechanical quantities that characterize the machine functioning, under any type of eccentricity. Specifically, the model is able to reproduce accurately the characteristic eccentricity fault related harmonics in the spectrum of the stator current.The proposed approach is validated through two different methods. First, using a finite elements (FEM) model, in order to validate the correctness of the proposed method for calculating self and mutual inductances, taking into account the non-uniform air-gap. Finally, through an experimental test-bed using a commercial induction motor with a forced mixed eccentricity fault, in order to validate that the full model correctly reproduces the phase currents in such a way that their spectra accurately show the harmonics related with the eccentricity fault, which are the basis of many MCSA diagnostic approaches.

Hybrid PWM Scheme for Pole-Phase Modulation Induction Motor Drive Using Carrier-Based Hexagonal and Octadecagonal SVPWM

In this article, the advantages of both octadecagonal space vector pulsewidth modulation (SVPWM) and hexagonal SVPWM are explored for a pole-phase modulation (PPM) induction machine (IM) drive applications. In the proposed scheme, a hexagonal SVPWM is used in the low-speed region and octadecagonal SVPWM is used during the high-speed region to achieve better performance over the entire speed range. With this proposed operation, the linear modulation region is enhanced by 9.15% as compared to conventional three-phase SVPWM in the high-speed region. The basic two-level nine-leg inverter is used to excite the nine-phase PPM IM. The finite-element model (FEM) of the PPM IM and inverter structure is simulated using ANSYS Maxwell-2D and Simplorer environment, respectively. The proposed method is verified experimentally on the prototype model of 5-hp nine-phase IM.

A Universal High-Frequency Induction Machine Model and Characterization Method for Arbitrary Stator Winding Connections

High-frequency modeling of induction machines plays an important role in investigating motor drive electromagnetic interference issues such as stator winding reflected-wave overvoltage and bearing discharging current. Characterization of high-frequency machine models requires measurements of machine's differential-mode (DM) and common-mode (CM) impedances up to tens of MHz. The machine's stator winding connections, e.g., single-, and series-, parallel-winding Y/Δ configurations, influence the measured DM and CM impedances and model parameters. In this paper, a universal high-frequency equivalent circuit model capable of representing induction machines with arbitrary stator winding connections is proposed. The new model features a simple structure with a straightforward characterization method. Specifically, only one stator winding configuration is required for impedance measurements to fully characterize the machine model for arbitrary stator winding connections. The proposed methodology is demonstrated using a 7.5 hp dual-voltage nine-terminal/lead induction machine and a drive system. The simulated DM and CM impedances as well as the motor overvoltages show excellent agreement with the experimental results. The proposed model and characterization method represent significant improvement in terms of accuracy, applicability/generality, and convenience compared to prior conventional models.