Speed Estimation Of Induction Motor Research Articles

Simple Stability Enhancement Method for Stator Current Error-Based MRAS-Type Speed Estimator for Induction Motor

In this article, the stability problem of the stator current error-based model reference adaptive system (MRAS) speed estimator for induction motor drive is discussed. The MRASCC that is analyzed in this article is created with a rotor flux simulator based on the stator current (first superscript C) and the stator current estimator (second superscript C), both adapted with the estimated rotor speed. As the original estimator is unstable in the regenerating mode, a simple stability extension solution is proposed based on the introduction of an auxiliary variable in the mathematical model of this estimator. The new adaptation rule is derived using the Lyapunov theory and stability range of a modified speed estimator is determined. This modification is compared with the existing solutions and analyzed in the simulation and experimental tests under motoring and regenerating modes of the drive system in open and closed–loop operation. It has been shown that the modified speed estimator with an additional variable adapted on-line is stable in the whole regenerating mode, contrary to the classical solution and does not require any modifications during the change from the regenerating to motoring mode and vice versa, as it is required in existing solutions.

Speed and torque estimation of variable frequency drives with effective values of stator currents

We introduce a new method for torque and speed estimation of induction motors under voltage/frequency (V/f) open-loop control. In contrast to existing approaches that need the phase current, the proposed algorithm only requires the effective value (root mean square) of the stator current and the synchronous frequency, which are usually available from variable frequency inverter (VFI) at no additional cost. Our approach is particularly useful for inverter-fed motor-pumps in which the load varies slowly. We demonstrate the proposed algorithm is able to estimate the pump torque, speed, differential pressure and flow rate in a hydraulic process with a progressive cavity pump.

A Novel Sliding Mode Observer With Optimized Constant Rate Reaching Law for Sensorless Control of Induction Motor

A novel sliding mode observer (SMO) with optimized constant rate reaching law for speed estimation in sensorless induction motor drives is proposed in this article to balance the dilemma between the requirement of fast reaching transient and the chattering reduction on sliding mode surface. By considering the reaching way to the sliding mode surface, a widely used reaching law called constant rate reaching law (CRRL) is introduced into SMO. However, SMO with CRRL cannot satisfy the rapidity of transient performance and the low chattering level simultaneously. To solve this problem, an optimized constant rate reaching law (OCRRL), which is based on the options of an exponential term that adapts to the variations of sliding mode surface and system states, is introduced into SMO. The proposed SMO with OCRRL is able to decrease the reaching time and suppress the chattering problem simultaneously. Simulation and experimental results both show the validity of the proposed approach.

Novel Complex-Valued Stator Current-Based MRAS Estimators With Different Adaptation Mechanisms

Recently, model reference adaptive systems (MRASs) used for mechanical speed estimation of induction motors have become the focus of interest in the literature due to their simple structures, easy implementations, and low computational burdens. In this article, stator current-based MRAS (MRAS $^{i_{s}} $ ), which is one of the most preferred MRASs, is first defined in the complex domain, and then the fixed-gain proportional-integral controller causing insufficient estimation performance in the adaptation mechanism is replaced by two different complex-valued adaptive algorithms. To prove the effectiveness of the proposed complex-valued MRAS $^{i_{s}} $ estimators, their estimation performances are compared by using real-time experimental results.

Sensor less Speed Estimation of an Foc Induction Motor Drive using Mras Speed Controller and Fuzzy Current Controller

This paper mainly presents fuzzy current controller depending on speed estimator of MRAS with field oriented controlled induction motor drives. This paper consists of three main techniques used for configurations of MRAS speed estimators that is Rotor Flux, Back - EMF and Instantaneous Reactive power. The MRAS estimators are then included into a direct field oriented controller and also a comparison is done between PI and fuzzy current controllers completely tested on MATLAB/SIMULINK. The resulting controller achieves an acceptable level of execution over wide range of good operating conditions.

Motor Current Signature Analysis for Speed Estimation

The induction motors are widely applied due to their low price and ruggedness. There are several methods for speed estimation in the literature. The optical tachometer is an expensive and less reliable method for the speed measurement. Hence sensor less method for speed estimation is an important topic of research. In this paper, speed estimation of induction motor using motor current signature analysis is done. The comparative study of different methods shows that the motor current signature analysis (MCSA) is more accurate in speed estimation. This technique is experimentally verified on a 5HP, 3.7kW, 1430rpm 415V, 50Hz, 7.5A, 3Ø squirrel cage induction motor using LabVIEW. The experimental and simulation results show that the overall speed estimation error is within 5 rpm.

MRAS-Based Speed Estimation of Induction Motor Drive Utilizing Machines' d- and q-Circuit Impedances

This paper proposes a new model reference adaptive system (MRAS) for the sensorless speed estimation of field-oriented induction motor (IM) drive utilizing d - and q -circuits effective impedances. The functional quantity of the MRAS, in this context, is the difference between the stator d - and q -circuits' effective working impedances. This unique structure does not require any flux computation while estimating speed. Moreover, the formulation is free from any resistance terms. The proposed estimator performs satisfactorily at all the operating points and exhibits stability in all the four quadrants of the drive's operation. The relevant stability and sensitivity studies, in this regard, are done in MATLAB/Simulink. Furthermore, the controller performance is validated experimentally by dSPACE-1103-based IM drive setup.

Second order sliding mode control with MARS speed estimation of linear induction motors considering unknown longitudinal end effects

AbstractThis paper presents a novel sensorless second order sliding mode control (SOSMC) scheme for linear induction motor (LIM), considering the longitudinal end effects. An adaptive super twisting controller (ASTC) is developed to eliminate the influence of the unknown bounded longitudinal end effects in mechanical loop scheme. Two super twisting controllers (STCs) are applied in electric loop schemes to overcome the high nonlinearity and reduce chattering. Moreover, a Model Adaptive Reference System (MARS) is designed to estimate LIM speed and the secondary flux. Finally, the proposed MARS based SOSMC scheme is validated with the Hardware‐in‐the‐loop (HIL) experiment test system.

A review on MRAS-type speed estimators for reliable and efficient induction motor drives

Induction machines have recently been very popular in variable-speed drives, because of their robust construction and relatively low manufacturing costs (brushless), maintenance-free and well-matured control methods. However, for high-precision control and efficiency optimization one needs the information on the rotor speed which can be measured using different speed sensors. All sensors require a mounting space and cabling, they also generate extra costs and reduce system reliability. Therefore, many of the recent research efforts have been dedicated to sensorless or encoderless electrical drives offering such considerable advantages as: lower cost, reduced size and hardware complexity of the drive system, elimination of sensor cables, lower maintenance requirements, possible operation in aggressive environment, higher noise immunity, reliable and user friendly operation. In this article all well-known sensorless techniques are shortly addressed, but the main focus is on the solutions based on the Model Reference Adaptive System (MRAS) concept. The mathematical models and schemes of all types of MRAS-type speed estimators known from the literature are gathered in this article. The comparative analysis of these speed estimators is done from the following points of view: the speed adaptation mechanism derivation based on the Lyapunov theory, stability problems near zero speed and in the regenerating operation mode, and the sensitivity of MRAS estimators to induction machine parameter changes.

An approximate high gain observer for speed-sensorless estimation of induction motors

Rotor speed estimation for induction motors is a key problem in speed-sensorless motor drives. This paper performs nonlinear high gain observer design based on the full-order model of the induction motor. Such an effort appears non-trivial due to the fact that the full-model at best admits locally a non-triangular observable form &#x0028 NTOF &#x0029, and its analytical representation in the NTOF can not be obtained. This paper proposes an approximate high gain estimation algorithm, which enjoys a constructive design, ease of tuning, and improved speed estimation and tracking performance. Experiments demonstrate the effectiveness of the proposed algorithm.

Low Speed Estimation of Sensorless DTC Induction Motor Drive Using MRAS with Neuro Fuzzy Adaptive Controller

<p>This paper presents a closed loop Model Reference Adaptive system (MRAS) observer with artificial intelligent Nuero fuzzy controller (NFC) as the adaptation technique to mitigate the low speed estimation issues and to improvise the performance of the Sensorless Direct Torque Controlled (DTC) Induction Motor Drives (IMD). Rotor flux MRAS and reactive power MRAS with NFC is explored and detailed analysis is carried out for low speed estimation. Comparative analysis between rotor flux MRAS and reactive power MRAS with PI as well as NFC as adaptive controller is performed and results are presented in this paper. The comparative analysis among these four speed estimation methods shows that reactive power MRAS with NFC as adaptation mechanism shows reduced speed estimation error and actual speed error at steady state operating conditions when the drive is subjected to low speed operation. Simulation carried out using MATLAB-Simulink software to validate the performance of the drive especially at low speeds with rated and variable load conditions.</p>

Speed Estimation of Three-Phase Induction Motor Using Kalman Filter

This paper presents the speed estimation of three-phase induction motor using Kalman filter. The state variables of this method are stator current and rotor flux. The estimation of the speed is also considered as a state. The Kalman filter uses the measured quantities such as stator voltages and currents for calculation. The results obtained by the simulation and the experiment show that the estimated values of the proposed method are near to the actual value. These values can track the actual values even though the load are varied.

Fast Initial Speed Estimation for Induction Motors in the Low-Speed Range

In this paper, a fast initial speed estimation method has been proposed for low rotational speed operation of speed sensorless induction motor drives based on the second-order differential of the secondary flux. The fast estimation can reduce an undesirable disturbance torque generation during the restart process. The effectiveness of the proposed method is confirmed by experiments. The estimation time has been compared with those in the literature and the benefit of the proposed method is confirmed.

Sensorless Induction Motor Drives Using Adaptive Flux Observer at Low Frequencies

Operation at low frequencies of sensorless drives using machine model-based estimation methods is a challenging issue. This paper proposes an adaptive flux observer (AFO) method of speed estimation for sensorless induction motor drives. The observer feedback gains are designed to guarantee accurate speed estimation, especially at low frequencies in the regenerating mode operation. A complete sensorless IM drive with the proposed AFO is executed in the laboratory. Extensive experimental results under different operating conditions are provided to prove the effectiveness of the proposed AFO, particularly under low stator frequencies in both motoring and regenerating modes of operation.

Quality Improvement of Speed Estimation in Induction Motor Drive by Using Fuzzy-MRAS Observer with Experimental Investigation

Our work is oriented to improve the quality of observation and estimating speed of rotation of the asynchronous machine. This study is designed to cope with problems related to parametric variation, non-measurability of flux, coupling between flux and torque, and observation of speed. The precise determination of these quantities, which we have concentrated in our work, has contributed to the improvement of the quality of control and observation of the asynchronous machine. Furthermore, the current study will be devoted to present an oriented rotor flow control of induction machine fitted with MRAS and FUZZY-MRAS sensor, a speed estimator based on the MRAS technique whose estimation mechanism is provided by fuzzy logic. The experimental results obtained will be demonstrated to show the feasibility and effectiveness of such an estimator through a comparison in order to illustrate the performance at low speed, load torque and reverse direction of rotation. Thus, with a simple comparison between observed and measured currents, we can get the necessary information to evaluate the error speed. Then, a regulator is applied to minimize the errors that are found. As a matter of fact, this regulator serves as an adaptation mechanism; it is noted that the FUZZY-MRAS observer is stable at high and low frequency and converge asymptotically at high frequency. It is also robust to an application of a load torque and also to the reverse direction of rotation.

Speed Estimation of Stator Field Orientation Control Induction Motor Drive Based on the Particle Swarm Optimization Algorithm

Speed Estimation of Stator Field Orientation Control Induction Motor Drive Based on the Particle Swarm Optimization Algorithm

Stability Analysis of Selected Speed Estimators for Induction Motor Drive in Regenerating Mode—A Comparative Study

This paper deals with the stability problem of selected induction motor speed estimators in the case of the regenerating mode operation. Two effective solutions are taken into consideration: adaptive full-order observer and model reference adaptive system-type estimator based on the current flux model and stator current estimation. The two estimation algorithms are compared in detail, namely their mathematical models, theoretical stability analysis, unstable operation areas, and stability improvement methods. The speed adaptation mechanism is extended with an additional shift angle in both cases. The theoretical analysis and simulation test results are validated by wide experimental tests.

Application of BEMF-MRAS with Kalman filter in sensorless control of induction motor drive

This paper describes an induction motor speed estimation using the observer with back electromotive force-based model reference adaptive system and Kalman filter. In the first part of the paper, there is a mathematical description of the rotor speed observer. The second part of the paper includes Kalman filter that is used for the filtration of measured stator currents and obtaining their time derivatives. The third part contains a description of the laboratory workplace with the induction motor drive and active load unit that was used for an experimental verification of the rotor speed observer. The last section of the paper shows experimental results that were obtained for different changes in the induction motor speed. The experimental results confirmed expected dynamic properties of the induction motor drive with sensorless control.

Design and field programmable gate array implementation of cascade neural network based flux estimator for speed estimation in induction motor drives

This study presents design and hardware implementation of cascade neural network (NN) based flux estimator using field programmable gate array (FPGA) for speed estimation in induction motor drives. The main focus of this study is the FPGA implementation of cascade NN based flux estimator. The major issues in FPGA implementation are optimisation of cost (resource) and execution time. A simple non-linear activation function called as Elliott function is used to reduce the execution time. To reduce the cost, and effectively utilise resource, the concept of layer multiplexing is adopted. The lowest bit precision needed for good performance of the estimator is identified and implemented. The proposed NN based flux estimator using simple excitation function and minimum bit precision is implemented using layer multiplexing technique. The designed estimator is tested on Spartan FPGA kit (3sd1800afg676-4) and the results obtained are presented.

Novel robust simultaneous estimation of stator and rotor resistances and rotor speed to improve induction motor efficiency

This paper presents a novel method of parallel stator and rotor resistances and rotor speed estimation for robust sensorless induction motor drive. Moreover, the estimated parameters have been used to calculate the optimal rotor flux for improving the motor efficiency. In this scheme, a parallel model reference adaptive system (MRAS) is designed to simultaneous estimation of rotor speed and rotor-stator resistances in order to achieve a high-precise control in a wide range of motor speed. The aim of design of one MRAS for parallel estimation of stator and rotor resistances and rotor speed is to save the implementation cost and to reduce the processes time. Moreover, the stability of the control scheme has been derived based on Popov's criterion to design the adaptation mechanisms. Digital simulation based on Matlab/Simulink is carried out to evaluate the effectiveness of the proposed scheme at different operating conditions. The simulation results demonstrate the effectivity of the proposed scheme at a wide range of speed under load disturbance and parameter variation.