Sensorless Vector Research Articles

Experimental determination of mechanical parameters in sensorless vector-controlled induction motor drive

High-performance industrial drives widely employ induction motors with position sensorless vector control (SLVC). The state-of-the-art SLVC is first reviewed in this paper. An improved design procedure for current and flux controllers is proposed for SLVC drives when the inverter delay is significant. The speed controller design in such a drive is highly sensitive to the mechanical parameters of the induction motor. These mechanical parameters change with the load coupled. This paper proposes a method to experimentally determine the moment of inertia and mechanical time constant of the induction motor drive along with the load driven. The proposed method is based on acceleration and deceleration of the motor under constant torque, which is achieved using a sensorless vector-controlled drive itself. Experimental results from a 5-hp induction motor drive are presented.

Real time implementation of a new fuzzy-sliding-mode-observer for sensorless IM drive

PurposeThe purpose of this paper is to improve the performance of sensorless vector control of induction motor drives by developing a new sliding mode observer for rotor speed and fluxes estimation from measured stator currents and voltages and estimated stator currents.Design/methodology/approachIn the present paper, the discontinuity in the sliding mode observer is smoothed inside a thin boundary layer using fuzzy logic techniques instead of sign function to reduce efficiently the chattering phenomenon that affects the rotor speed.FindingsThe feasibility of the proposed fuzzy sliding mode observer has been verified by experimentation. The experimental results are obtained with a 1 kW induction motor using a dSPACE system with DS1104 controller board showing clearly the effectiveness of the proposed approach in terms of dynamic performance compared to the classical sliding mode observer.Practical implicationsThe experimental results of the whole control structure highlights that this kind of sensorless induction motor drive can be used for variable speed drive in industrial applications such as oil drilling, electric vehicles, high speed trains (HSTs) and conveyers. Such drives may work properly at zero and low speed in both directions of rotation.Originality/valueBoth the proposed speed observer and the classical sliding mode observer have been developed and implemented experimentally with other adaptive observers for detailed comparison under different operating conditions, such as parameter variation, no-load/load disturbances and speed variations in different speed operation regions.

Study on Speed Sensor-less Vector Control of Induction Motors Based on AMEsim-Matlab/Simulink Simulation

Abstract The model of speed sensor-less vector control system of induction motors has been built on the AMEsim and Matlab/Simulink platform, AMEsim and Simulink can be connected by creating an S-function interface. The results of Co-simulation indicate that the algorithms of model reference adaptive system (MRAS) based on counter electromotive force (EMF) can estimate the speed with some accuracy in static and dynamic conditions and make the electro-hydraulic power steering (EHPS) system offer the assist force as quickly as the sensor-based system. So the proposed model and control algorithms are correct and have reached the expectation.

Speed sensorless vector control of parallel-connected three-phase two-motor single-inverter drive system

This paper presents the characteristic behavior of direct vector control of two induction motors with sensorless speed feedback having the same rating parameters, paralleled combination, and supplied from a single current-controlled pulse-width-modulated voltage-source inverter drive. Natural observer design technique is known for its simple construction, which estimates the speed and rotor fluxes. Load torque is estimated by load torque adaptation and the average rotor flux was maintained constant by rotor flux feedback control. The technique’s convergence rate is very fast and is robust to noise and parameter uncertainty. The gain matrix is absent in the natural observer. The rotor speed is estimated from the load torque, stator current, and rotor flux. Under symmetrical load conditions, the difference in speed between two induction motors is reduced by considering the motor parameters as average and difference. Rotor flux is maintained constant by the rotor flux control scheme with feedback, and the estimation of rotor angle is carried out by the direct vector control technique. Both balanced and unbalanced load conditions are investigated for the proposed AC motor drive system. Experimental results presented in this paper show good agreement with the theoretical formulations.

Investigation of reductions in motor efficiency and power factor caused by stator faults when operated from an inverter drive under open loop and sensorless vector modes

ABSTRACTThe introduction of Variable Speed Drives (VSD) motor driven systems in industry is driven by the desire to increase motor efficiencies in plant. The efficiency savings are usually determined by initial energy assessments which consider factors such as the motor load type and operating conditions where the motor actual load may also be measured. However, once the system is installed and in operation, the designed-in energy efficiency of these systems may remain unchecked throughout the lifetime of the installation. Efficiency reductions may be caused by mechanical or electrical degradation of equipment that could remain undetected by the drive or user whilst the equipment appears to operate as normal. On larger systems, the financial cost of reduced efficiency can be significant. The aim of this paper is to simulate minor deteriorations in the operating conditions of a standard motor controlled from a VSD and ascertain if the worsening condition can be detected at an early stage. The deterioration in motor condition will be small enough to remain undetected by the VSD and not cause a drive fault. This paper also reviews the effect of the introduced motor imbalance on motor efficiency and introduces power factor measurement methods which can be a useful indicator of increased operating costs for equipment. Test results from the two drive operating modes of Volts/Hertz (v/f) and Sensorless Vector (SV) are compared. This is to determine if there is any noticeable difference in the measurements obtained for efficiency and power factor between drive operating modes.

The P/PI Mode Switching Method of Gopinath Flux Observer for Sensorless Vector Control of Induction Motors

The P/PI Mode Switching Method of Gopinath Flux Observer for Sensorless Vector Control of Induction Motors

MOPSO-based predictive control strategy for efficient operation of sensorless vector-controlled fuel cell electric vehicle induction motor drives

This paper introduces an optimal control strategy of model-based predictive control (MPC) based on multiobjective particle swarm optimization (MOPSO) for a sensorless vector control induction motor, which is used in a fuel cell electric vehicle drive system. The proposed MPC-MOPSO algorithm is implemented to tune the weighting parameters of the MPC controller to tackle all the conflicting objective functions. The paper handles the following fitness functions: minimizing the speed error, minimizing the torque ripple, minimizing the DC-link voltage ripple, and minimizing machine flux ripple. Computer simulations studies have been completed utilizing MATLAB/Simulink with a specific end goal of assessing the dynamic performance of the proposed MPC-MOPSO optimal controller and comparing it with single-objective particle swarm optimization and traditional PI controllers. The simulation results demonstrate the good dynamic response of the proposed MPC-MOPSO optimal tuning strategy over the traditional PI controllers for more accurate tracking performance through the whole speed range, especially at starting conditions and load change disturbances.

鉄損を考慮した適応二次磁束オブザーバを用いた速度センサレスベクトル制御系の安定性解析

Vector control of induction motor is widely used in industrial applications. Many methods have already been proposed in this field. There are many restrictions involved in using mechanical sensor; moreover, the extra expense and allocation problems make using such sensor difficult in some cases. Stability analysis of a speed sensorless vector control system based on the feedback of the estimated torque-producing current is performed.

Novel Observer Scheme of Fuzzy-MRAS Sensorless Speed Control of Induction Motor Drive

This paper presents a novel approach Fuzzy-MRAS conception for robust accurate tracking of induction motor drive operating in a high-performance drives environment. Of the different methods for sensorless control of induction motor drive the model reference adaptive system (MRAS) finds lot of attention due to its good performance. The analysis of the sensorless vector control system using MRAS is presented and the resistance parameters variations and speed observer using new Fuzzy Self-Tuning adaptive IP Controller is proposed. In fact, fuzzy logic is reminiscent of human thinking processes and natural language enabling decisions to be made based on vague information. The present approach helps to achieve a good dynamic response, disturbance rejection and low to plant parameter variations of the induction motor. In order to verify the performances of the proposed observer and control algorithms and to test behaviour of the controlled system, numerical simulation is achieved. Simulation results are presented and discussed to shown the validity and the performance of the proposed observer.

Implementation of a novel full-order observer for speed sensorless vector control of induction motor drives

In this paper, the implementation of a novel speed sensorless vector control of induction motor (IM) drive based on full-order observer is presented. The adaptive full-order observer based on IM equations has been used to estimate stator currents and rotor flux. A novel feedback gains of full-order observer have been proposed to satisfy the stability of the system. The speed is estimated depending on the error between the actual and estimated stator currents. However, the performance of this scheme deteriorates when approaching the zero speed zones because of the effect of the variation of the stator resistance and the problem of the stability. The stator resistance has been estimated in parallel with the rotor speed to compensate the error in estimated rotor speed in the low speed region. Lyapunov’s stability criterion is employed to estimate rotor speed and stator resistance. All gains of all PI controllers have been calculated based on the linearized models of the IM. This paper presents an experimental evaluation of the performance of speed observer when working at very low speed. Synthesis of the controller has been presented. The simulations and experimental results prove excellent steady-state and dynamic performances of the drive system in a wide speed range, especially at very low speeds, which confirms validity of the proposed scheme.

Single Inverter Fed Speed Sensorless Vector Control of Parallel Connected Two Motor Drive

This paper describes a speed sensorless vector control method of the torque for cost-effective parallel-connected dual induction motor fed by a single inverter. A natural observer with load torque adaptation is employed to estimate the speeds of the same rating induction motors connected in parallel and fed by a single inverter. The speed difference between the two induction motors for unbalanced load conditions is less in natural observer than the conventional adaptive rotor flux observer. Direct field oriented control is used to calculate the rotor angle from the estimated rotor fluxes and the mean rotor flux is kept constant by rotor flux feedback control. The simulation and experimental results of studies are demonstrated for various running conditions to prove the effectiveness of the proposed method. The closed loop speed control operation with inner current control was performed by TMS320F2812 processor.

Equivalent two-phase mutual inductance model and measurement algorithm of three-phase bearingless motor

For a bearingless motor that has two sets of stator windings, i.e. torque windings and suspension windings, the mutual inductance between the two sets of stator windings is a critical parameter; it is the basis of displacement sensorless control technology. Aiming at a three-phase bearingless motor, the equivalent two-phase mutual inductance model between two sets of stator windings is deduced. Then, based on the mutual inductance measurement method of a simple two-phase bearingless motor, a novel measurement algorithm of the equivalent two-phase mutual inductance is proposed, and the proposed measurement algorithm is applicable for a three-phase bearingless motor. Finally, based on a three-phase bearingless induction prototype motor, the experimental measurement of the equivalent two-phase mutual inductance is carried out. From the experimental results, it is clear that within the limited radial eccentricity of the rotor, the measured value of the equivalent two-phase mutual inductance is approximately proportional to the radial displacement of the rotor, and the correction coefficient kc of the equivalent two-phase mutual inductance model is derived; the consistency between measured and calculated values has verified the validities of the equivalent two-phase mutual inductance model and the proposed measurement algorithm from one instance. Thus, the theory foundation has been laid for research on the displacement sensorless vector control technology of a three-phase bearingless motor.

New variable gain super-twisting sliding mode observer for sensorless vector control of nonsinusoidal back-EMF PMSM

This paper presents a new discrete-time super-twisting sliding mode observer with variable gains for sensorless nonsinusoidal vector control of permanent magnet synchronous motors. This observer is adopted to estimate the back electromotive forces (back-EMF) that are required for the rotor speed estimation and for the nonsinusoidal vector control. In addition, their gains are time-varying to minimize the chattering. So, they are adjusted based on internal states of the super-twisting algorithm. The stability analysis is investigated from the Lyapunov theory for discrete-time systems. Finally, simulation and experimental results are presented to demonstrate the good performance and the effectiveness of the proposed observer.

Sensorless Vector Control of Induction Motor Based On Extended Kalman Filter and Fuzzy Controller

This paper depicts the vector control of an induction motor by the speed estimation utilizing an extended Kalman filter and fuzzy controller. In this paper, the rotor speed is viewed as a parameter, and the composite state is made out of the first state and the rotor speed. The extended Kalman filter is utilized to distinguish the speed of an induction motor and rotor flux in light of the deliberate amounts, for example, stator currents and DC join voltage. The assessed speed is utilized for vector control and general speed control. The current control is performed at synchronous rotating reference frame, and the assessed speed data is utilized for reference frame transformation of the current controller. PC reproduction of the speed control has been completed to affirm the speed's helpfulness estimation calculation. The error between the genuine speed and the evaluated speed is inside of a couple rpm even at the low and high speeds.

Parallel Stator Resistance Estimator Using Neural Networks for Rotor Flux Based Model Reference Adaptive System Speed Observer

Model reference adaptive system schemes offer simpler implementation and require less computational effort compared to other speed sensorless methods. The performance of rotor flux based model reference adaptive system schemes at low-speed operation is poor because of parameter sensitivity and presence of the integrator in the reference model. As stator resistance inevitably varies with temperature, for accurate operation at low speeds, an appropriate online identification algorithm for the stator resistance is required. In this article, a neural network based parallel stator resistance and rotor speed estimator has been proposed to simultaneously rectify the limitation of model reference adaptive system schemes, i.e., stator resistance variation and DC offset due to integrator, employing a neutral network in stator resistance estimator and modifying the reference model by adding a compensating voltage term. An indirect sensorless vector control scheme has been simulated and experimentally validated using the dSPACE DS-1104 R&D controller board (dSPACE GmbH, Paderborn, Germany) to verify the performance of drives at different operating conditions.

Sensorless Vector Control of Induction Motors Using Minimum Dimensional Flux D‐State Observer with Instantaneous Speed Estimation

SUMMARYThis paper proposes a new sensorless vector control method for induction motors using a minimum dimensional flux D‐state observer with instantaneous speed estimation. First, the D‐state observer with a new design rule of constant observer gains is established in a different way. Second, a new speed estimator using flux estimates produced by the observer is established on the basis of the fundamental relationship between the rotor flux and the slip frequency. Speed estimates are reused in the observer as feedback. Characteristic analyses and the usefulness of the proposed vector control method are verified by simulations.

Influence of back-EMF and current harmonics on sensorless control performance of single and dual three-phase permanent magnet synchronous machines

Purpose – The purpose of this paper is to investigate the influence of back-EMF and current harmonics on position and speed estimation accuracy for single and dual three-phase (DTP) permanent magnet synchronous machines (PMSMs) with two fundamental-model-based sensorless control strategies which are widely utilized for AC machines, i.e. flux-linkage observer (FO) and simplified extended Kalman filter (EKF). Design/methodology/approach – The effect of distorted back-EMF is studied for sensorless vector control of single three-phase PMSM. For the influence of current harmonics, unlike the existing literature where the current harmonics are deliberately injected, in this paper, sensorless switching-table-based direct torque control (ST-DTC) strategies for DTP-PMSM which inherently suffer from non-sinusoidal stator currents in addition to the distorted back-EMF, are investigated experimentally. Findings – By employing the FO and simplified EKF-based sensorless vector control of single three-phase PMSM, it can be concluded that the rotor position estimation accuracy is less affected by the back-EMF harmonics when the simplified EKF method is utilized since it is less sensitive to such noises. When the influence of non-sinusoidal stator currents together with back-EMF harmonics is investigated for the conventional and modified ST-DTC of DTP-PMSM, it is indicated that the simplified EKF exhibits better position and speed estimation accuracy in both the conventional and modified ST-DTC strategies. In addition, its steady-state performance shows a slight superiority over that based on FO, in terms of flux and torque ripples, and THD of phase currents. For the dynamic performance, the estimated speed of simplified EKF shows less phase lag and fluctuations compared to that of FO. Originality/value – This paper introduces the influence of back-EMF and current harmonics on sensorless control performance for single and DTP PMSMs. Detailed experimental results show that the simplified EKF exhibits better rotor position and speed estimation accuracy compared to that of FO due to its higher noise-rejection ability.

New Model Reference Adaptive System Speed Observer for Field-Oriented Control Induction Motor Drives Using Neural Networks

One of the primary advantages of field-oriented controlled induction motor for high performance application is the capability for easy field weakening and the full utilization of voltage and current rating of the inverter to obtain a wide dynamic speed rangeThis paper describes a Model Reference Adaptive System (MRAS) based scheme using Artificial Neural Network (ANN) for online speed estimation of sensorless vector controlled induction motor drive. The proposed MRAS speed observer uses the current model as an adaptive model. The neural network has been then designed and trained online by employing a back propagation network (BPN) algorithm. The estimator was designed and simulated in Matlab/Simulink. Simulation result shows a good performance of speed estimator. The simulation results show good performance in various operating conditions. Also Performance analysis of speed estimator with the change in resistances of stator is presented. Simulation results show this estimator robust to parameter variations especially resistances of stator.

Analiza bezczujnikowego układu wektorowego sterowania silnikiem indukcyjnym z kompensatorem neuronowo rozmytym

CC . Badania eksperymentalne wykonano przy wykorzystaniu ukladu szybkiego prototypowania DS1103. Abstract. The possibility of application the Adaptive Neuro Fuzzy Controller - ANFC in the structure of sensorless vector controlled induction motor drive (DTC-SVM and DFOC) as a so-called neuro fuzzy speed compensator are presented in the paper. In the paper the experimental results of the vector controlled induction motor drive system under different conditions are presented. Drive operations in the low speed region are presented. To the rotor / stator flux and rotor speed reconstruction the MRAS CC estimator is used. DS1103 card is applied in the experimental tests. (Analysis of

Characteristics of Speed Sensorless Vector Controlled Induction Motor with High Efficiency Taking Core Loss into Account

This paper presents the characteristics of a speed sensorless vector control method of an induction motor operating at high efficiency and high response, in which core loss is taken into account. An improved method of speed estimation that operates on the principle of speed adaptive flux and current observer has been proposed. An observer is basically an estimator that uses a plant model and a feedback loop with measured stator voltage and current. Simulation results show that the proposed direct field oriented control with the proposed observer provides good performance characteristics. The IM is fed by an indirect power electronics converter. This indirect converter is controlled by a pulse width modulation PWM technique that enables minimization of harmonics introduced by the line converter, as well as the control of the power factor and DC-link voltage. We study the robustness of the overall system- using simulation of different modes to operating modes and varied parameters.