Model Of Induction Motor Research Articles

State Space-Vector Model of Linear Induction Motors Including End-Effects and Iron Losses Part I: Theoretical Analysis

This is the first part of the article, divided into two parts, dealing with the definition of a space-vector dynamic model of the linear induction motor (LIM) taking into consideration both the dynamic end-effects and the iron losses and its offline identification. This first part specifically treats the theoretical formulation of this model, which has been expressed in a state form, so to be, in perspective, suitably adopted for developing novel nonlinear control techniques, nonlinear observers as well as electrical losses minimization techniques. Besides the formulation of the dynamic model in space-vector state form, a steady-state analysis is proposed, highlighting the combined effects of the dynamic end-effects and the iron losses on the main electrical quantities of the LIM.

Modelling and investigating the impact of asynchronous inertia of induction motor on power system frequency response

Besides synchronous inertia, asynchronous inertia of induction motor also widely exists in power systems, but its effect on system frequency response has not been well studied. A simplified transfer function model of induction motor is derived based on the detailed model. The model is regarded as a decaying proportion of the consumed power to the frequency deviation. Three key features of the model are the immediate proportion, the steady-state proportion and the decaying time constant. Their affecting factors are also studied. Then the model is added to the system frequency response model to study the effect of induction motor. There are three key factors of induction motor affecting frequency response, the sensitivity of electromagnetic torque to slip, the sensitivity of mechanical load torque to rotor speed, and the inertia. Their effects are analytically analyzed. The asynchronous inertia only affects the maximum frequency deviation, and a large inertia reduces the maximum frequency deviation. However, it is acceptable to neglect the asynchronous inertia and represent the induction motor with static model considering steady-state frequency sensitivity. The derived conclusions are validated with simulation results.

Online maximum torque per ampere control for induction motor drives considering iron loss using input–output feedback linearisation

This study presents a novel online, accurate and simple model-based maximum torque per ampere (MTPA) strategy for input–output feedback linearisation control of induction motor (IM) drives. Despite conventional MTPA control principles which are under the assumption of iron loss neglecting, the proposed strategy takes iron loss effect into account. This study highlights the iron loss influence on MTPA scheme. Firstly, the cross-coupling effects in the IM model and torque non-linearity due to the iron loss in torque–speed characteristics of the IM are discussed. The criterion for the MTPA scheme is then introduced and investigated by gradient approach so that when the gradient vectors of the torque and stator current magnitude are parallel, the MTPA strategy is satisfied. Finally, to confirm the validity of the proposed control scheme, experiments are carried out.

Robust Time-Varying Synthesis Load Modeling in Distribution Networks Considering Voltage Disturbances

Uncertain power sources are increasingly integrated into distribution networks and causes more challenges for the traditional load modeling. A variety of distributed load components present dynamic characteristics with time-varying parameters. Toward the end, this paper proposes a robust time-varying parameter identification (TVPI) method for synthesis load modeling in distribution networks, including time-varying ZIP, induction motor, and equivalent impedance models. The nonlinear optimization model is developed and solved by the nonlinear least square (NLS) to find the minimum error between estimated outputs and measurements. To cope with TVPI deteriorated by voltage disturbances, dynamic programming is first used to detect the disturbance. Then, a robust TVPI engine is designed to constrain the estimated time-varying parameters within a stable range. Furthermore, advanced tolerance thresholds are also required during iterations of NLS. Numerical simulations on the 9- and 129-bus distribution systems verify the effectiveness and robustness of the proposed TVPI method. Also, this method can be robust to the ambient noise of measurements.

Stable Operation Method for Speed Sensorless Induction Motor Drives at Zero Synchronous Speed With Estimated Speed Error Compensation

The methodologies applied to speed sensorless induction motor drives (SSIMD) can be divided into two categories. The first category makes use of the fundamental model of induction motor to establish speed and flux observers. However, the rotor speed is unobservable with these methods when synchronous speed is close to zero. The second category makes use of anisotropies of induction motor to observe rotor speed. However, the anisotropies of induction motor are too weak to extract rotor speed information. Consequently, the unstable problem of SSIMD at low synchronous speed (including zero synchronous speed) has not been solved yet by now. In this paper, a virtual voltage injection method is proposed to solve this problem. The voltage is only injected into observer. The observability of rotor speed based on proposed virtual voltage injection is analyzed. Because the injected voltage into observer results in estimated speed error, a compensation method is proposed then. The stability of the system with virtual voltage injection and corresponding compensation method is analyzed by the input-state-stability concept. Finally, the feasibility of the proposed method is verified by experiments.

Identification of Induction Motors Using Smart Circuit Breakers

The problem of estimating the parameters of induction motor models is considered, using the data measured by a circuit breaker equipped with industrial sensors. The measured data pertain to direct-on-line motor startups, during which the breaker acquires three-phase stator voltage and current derivative. This setup is novel with respect to previous contributions in the literature, where voltage and current (and possibly also rotor speed) are considered. The collected data are used to formulate a parameter identification problem, where the cost function penalizes the discrepancy between simulated and measured derivatives of the stator currents. The resulting nonlinear program is solved via numerical optimization, and a number of algorithmic improvements with respect to the literature are proposed. In order to evaluate the goodness of the obtained results, an experimental rig has been built, where the motor's voltages and currents are simultaneously acquired also by accurate sensors, and the corresponding identification results are compared with those obtained with the circuit breaker. The presented experimental results indicate that the considered industrial circuit breaker is able to provide data with high-enough quality to carry out model-based nonlinear identification of induction machines. The identified models can then be used for several further applications within a smart grid scenario.

Estimation of Voltage Unbalance Attenuation Caused by Three-Phase Induction Motors: An Extension to Distribution System State Estimation

With the increased interest in controlling and managing voltage unbalance (VU), network operators are now increasingly being motivated to obtain the state of their networks with greater details. Distribution system state estimation (DSSE) is a prominent tool that enables network operators to estimate the level, location, and related impacts of VU. DSSE techniques developed to date which use the polynomial or exponential load models are deficient in recognizing VU attenuation associated with three-phase induction motors (IMs) that are directly connected to the ac network. Adoption of adequate three-phase models of IMs, which are used in full unbalanced load flow, into the existing DSSE techniques is not feasible due to several factors including requirement of extensive data, additional computational efforts, and major constraints related to incorporating the necessary modifications. As a solution, this paper proposes a novel formulation for postprocessing the results of current DSSE techniques to reflect the aforementioned behavior of IMs. Simulations are carried out using the IEEE 13 bus distribution network for a range of scenarios to verify the developed methodology. The work presented in relation to VU attenuation in interconnected networks also complements the existing treatise in IEC documentation that only deals with radial networks.

Incipient winding fault detection and diagnosis for squirrel-cage induction motors equipped on CRH trains

Stator/rotor winding faults are the common faults in squirrel-cage induction motor systems, which motivates the study of incipient fault detection and isolation (IFDI) to improve the safety and reliability of CRH (China Railway High-speed) trains. In this paper, a dynamic model for squirrel caged induction motor in d-q coordinate system is established firstly, further, the models and characteristics of incipient broken-rotor-bar fault and turn-to-turn short fault are analyzed. After that, a novel robust diagnosis design is proposed for the possible incipient stator/rotor winding faults. Experimental analyses show that the detection and isolation scheme designed in this paper provides high sensitivity and accurate isolation to incipient winding faults.

Modeling and Simulation of Five-Phase Induction Motor Fed With Pulse Width Modulated Five-Phase Multilevel Voltage Source Inverter Topologies

This paper presents modelling and simulation of five-phase induction motor fed with pulse width modulated five-phase multilevel voltage source inverter. The conventional and diode clamped multilevel five-phase inverter configurations are reviewed with pulse width modulation (PWM) techniques. A hybrid three-level inverter topology with less number of components count is proposed for five-phase induction motor drive. The dynamic analysis of five-phase voltage equations in d-q axis of the induction motor are stated and modelled using Matlab/Simulink/Simscape blocks. The simulation results based on conventional and threelevel five-phase inverters are displayed while the hybrid inverter topology showed some better performance based on the following: : at 0.0127secs maximum torque of 34.54Nm occurred, maximum stator current occurred for 0.18secs with a value of 10A, 9.99% total harmonic distortion was obtained and 15KW power rating was obtained.

Equivalent Circuit Model of Novel Solid Rotor Induction Motor with Toroidal Winding Applying Composite Multilayer Theory

In this work, a novel solid rotor induction motor with toroidal winding (N-TWSRIM) is proposed and its structure and main structural parameters are given. The operating principle is analyzed in accordance with the movement of the armature magnetic field at different times. An equivalent circuit model (ECM) of the N-TWSRIM is established based on composite multilayer theory to analyze and calculate motor performance quickly and accurately. Electromagnetic performance, which includes output torque, stator current, and power factor under different slip, is calculated with ECM, and its results are compared with those of the finite element method. A prototype of the N-TWSRIM is built and experimented on to validate the correctness of the operating principle and ECM. Experimental results on stator current and torque are consistent with the finite element and analytical results.

Euler‐Lagrange equation: Case of energy‐optimal approach for induction machine

SummaryThe optimal control problem that hinges on the Euler‐Lagrange equation can be applied to electric‐machine drives and the necessary and sufficient optimality conditions around the system control and the control variables can be designed in a congruent way. In this paper, a variational problem is proposed to minimize energy consumption by an Induction Motor (IM) under a Rotor Field–Oriented Vector Drive (RFOVD) during torque and speed transients. The optimal stimulus is to take into account real applications, like perturbed load torques, and an abrupt speed input. The approach consists of an off‐line algorithm that minimizes a cost functional or integral of the weighted sum of IM energy/power under the dynamic stress of the rotor flux and of rotation speed. The variational problem leads to a nonlinear differential equation known as the Euler‐Lagrange equation. A new method is suggested to run out an analytical solution and results in a time‐varying rotor flux considered as the optimal state variable of the dynamic IM model that saves energy of the IM drive under RFOVD. This solution provides loss‐minimization in steady‐state operations at an infinite horizon and performs adaptive suboptimal minimum‐energy consumption for torque transients. Simulation and experimental results are fully performed on 1.5‐kW laboratory IM, and prove the validity of the proposed method for both steady‐state and transient‐IM drive operations.

On-Line Parameter Identification of a Squirrel Cage Induction Motor

Based on the principle of coordinate transformation, a mathematical model of induction motors in the three-phase stationary coordinate system was transformed to that in the synchronous rotating coordinate system. For motors with low-speed rotors, the multi-variable, high-order, strong-coupling and nonlinear equation of motors was further transformed to a linear equation. However, it was found difficult to solve the deduced linear equation through the method of least squares due to its high singularity. The steady-state stator resistance could be predetermined by temperature revision on the stator resistant in the motor nameplate. Identification of four motor parameters (Ls,M, Rr, Lr) was followed by the recursive least-squares method. Simulations of motor parameter estimation were carried out in Simulink of Matlab. The recursive least-squares method was used to deal with the measured data. The results demonstrate that the real-time electrical parameters (Ls, σ, Tr) can be accurately predicted. Given the assumption of Ls = Lr in the classical motor theory, the other three electrical parameters (M, Rr, Lr) can also be identified. The identification of these parameters is of great importance for the analysis, control and fault diagnosis of induction motors.

Modelling of soft starters for automated electric drive

In this paper we investigated the conditions of favorable start-up of fixed-speed induction motors in order to increase the functional reliability of the engines. The methods of controlled soft start of induction electric motors with a squirrel-cage rotors are investigated. The study of the mathematical model of induction motors for determining the dependencies of reducing the dynamic component of the transient electromagnetic moment and the magnitude of the starting current. A computer simulation to identify the effectiveness of different methods of controlled start-up of induction motor was carried out. To generate the starters’ models, the MatLab modelling application, Simulink and SimPowerSystems block libraries were used. Based on the results of transient processes simulation in MatLab, the comparative characteristics for different methods of starting an induction motor were given.

V/F based Multi-Phase Induction Motor Drive For PV Powered Boat Applications

This paper presents a detailed discussion about single stage inverter to drive the multi-phase V/F induction motor to propel boat fed from stand-alone photovoltaic (PV) system, increases compactness, reliability and economical features to the entire system. To drive the boat using non-linear multi-phase induction motor from a non-linear PV source, under maximum power point condition is a tedious task. Though, single stage systems seem to simple, obtaining various control functionalities such as MPPT operation, model reference speed estimation, V/F speed control methods along with controller design and modulator functions from only one power electronics converter increases the design complexity to the designer. While performing MPPT and speed estimation operations in closed loop, re-checking ability is integrated to the inverter fed V/F control induction motor initiative for superior exactness results improves the dynamic performance, and also energy saving to end-user. Closed-loop (CL) boat sailing operation with load torque and model reference adaptive based speed estimation using multi-phase induction motor model along with the MPPT P&O algorithm, is used to generate reference command to the controller, and designed controller ensure to track this reference by producing controller voltage to modulator. Simple Sine PWM is adopted for the generation PWM pulses to the inverter in this drive to enhance the design simplicity. Proposed method is simulated using MATLAB/SIMULINK and closed loop solution at both different irradiations and load torque conditions presented. The simulation marks illustration that planned method is inexpensive, efficient, performance is reliable and superior.

2D Hybrid Steady-State Magnetic Field Model for Linear Induction Motors

This paper presents a 2D hybrid steady-state magnetic field model, capable of accurately modeling the electromagnetic behavior in a linear induction motor, including primary slotting, finite yoke length, and longitudinal end-effects by primary motion. This model integrates a complex harmonic modeling technique with a discretized magnetic equivalent circuit model. The Fourier model is applied to regions with homogeneous material properties, e.g., air regions and the track of the motor, while the magnetic equivalent circuit (MEC) approach is used for the regions containing non-homogeneous material properties, e.g., the primary of the linear induction motor (LIM). By only meshing the domains containing highly-permeable materials, the computational effort is reduced in comparison with the finite element method (FEM). The model is applied to a double-layer single-sided LIM, and the resulting thrust and normal forces show an excellent agreement with respect to finite element analysis and measurement data.

Modified Switching Table-Based Direct Torque Control of Six-Phase Induction Motor Drive

This paper presents “Switching Table based Direct Torque Control” of Six-Phase Induction Motor (SPIM) Drive. The SPIM consists of two sets of stator windings spatially shifted by an angle of 30°. The extension of DTC technique of three-phase induction motor for a six-phase induction motor yields conventional DTC, in which one large voltage vector per sampling period is utilized. This technique suffers from large stator current harmonics of the order of 6k ± 1 (k = 1, 3, 5..). Initially, the conventional DTC technique has been implemented for comparison purpose. Further, its performance is improved by using two voltage vectors in each sampling period. In order to investigate the performance of ST-DTC based SPIM, a simulation study is carried out under different operating conditions. To validate the simulation results, a prototype model of six-phase induction motor rated for 1.5 kW, 200 V, 50 Hz is developed. Results obtained during simulation and experimentation show the effectiveness of modified ST-DTC technique in the reduction of stator current harmonics.

Modeling and Control of Low Switching Frequency High-Performance Induction Motor Drives

Complex state variables are used to study the dynamic behavior of induction motors considering the propagation in space of the distributed magnetic field inside the machine. The objective of this paper is to improve the dynamics of pulsewidth modulation inverters in medium-voltage drive systems. To keep the dynamic losses of the power devices at a tolerable level, the switching frequency must be below 1 kHz. The sampling rate of the digital signal processing system is then low which introduces considerable signal delay. The delay has an adverse influence on the dynamic behavior of the current control system. It introduces undesired cross coupling between the current components $i_{d}$ and $i_{q}$ . The degree of cross coupling is described by a cross-frequency transfer function. It is shown that the mechanism of cross coupling is different and more adverse than the conventional theory discloses. A current controller structure having poles and zeroes of the single-complex type is synthesized. Cross coupling is completely eliminated at any low switching frequency. Experimental results demonstrate that high dynamic performance and zero cross coupling is achieved even at very low switching frequency.

Problem-Based Learning Model for Three-Phase Induction Motor

This study aims to examine the Problem-Based Learning(PBL) model to improve the understanding of electromagnetic induction material in three-phase induction motor. Most of the students attending the Electrical Machine course have low understanding upon the working principles of the three-phase induction motor, in particular the basic theory of the relationship between the electromagnetic field and the three-phase induction motor. This study involved seventeen students of Electrical Engineering Education Study Program of Universitas PGRI Madiun in East Java. Data were collected through observation and tests, with the statistical test of research using paired sample t-test. This quasi-experimentresearch employed one-group pre-test and post-test design. The results showed that the application of PBL model with video simulation and practicesimprove students’understanding of the materials. The learning process by utilizing simulated animation video and the practices of unloading three-phase induction motors directly, the students’understanding of the working principles of three-phase induction motors increases with the average of N-Gain score. These results indicate the use of video and hands-on practice become effective way to deliver complex and abstract material to students. It is also believed that the learning on electromagnetic induction can be carried out more efficiently. Additionally, such learning model is believed to ease physics education.

Loss minimization of induction machines during torque transients

This article presents a new design of an energy optimization approach to induction motor drives. The proposed control strategy is based on a designed cost function given as a weighting sum of power and energy models and subjected to the dynamic of a low-order current-fed induction motor model, which considers only the dynamics of the rotor flux and the mechanical equation as constraints to the problem. Such a strategy uses the concept of off-line optimal closed-loop control. Considering the case of a random desired torque, the resolution with suboptimal conditions allows a time-varying rotor flux that converges to the optimal solution and minimizes energy in a dynamic operation. This solution is presented in an analytical form and is dedicated to optimizing a transient regime characterized by a random load torque. This command law will become invariant with respect to time and will asymptotically tend to a stationary optimal solution. Aiming to check the validity of the proposed algorithm, a comparison study is conducted between rotor-field-oriented control operating with a suboptimal rotor flux and rated constant-flux control. The simulation and experimental results obtained for a 1.5-kW laboratory induction motor demonstrate the effectiveness of the proposed strategy.

Discrete-time adaptive fuzzy speed regulation control for induction motors with input saturation via command filtering

A discrete-time adaptive fuzzy control method is introduced to achieve the speed regulation for induction motors (IMs) with input saturation via command filtering in this paper. First, the continuous model of IMs drive system is transformed into discrete-time form by using Euler formula. Then, the fuzzy logic systems are used to approximate the unknown nonlinear functions in the discrete-time drive system. In addition, the command filtering control method is introduced to overcome the “explosion of complexity” problem in the design process of traditional backstepping method. It is verified that all the closed-loop signals are bounded and the outputs can track the given reference signals well. Finally, simulation results illustrate the validity of the discrete-time control method.