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The open-ended winding configuration allows feeding an electric motor from two sides. If one of them is connected to an inverter closed on a floating capacitor, operating as an active power filter, it is possible to obtain several benefits over the traditional configuration, such as an extended field weakening speed range and a lower current ripple. However, the additional converter causes switching...
The paper deals with a full sliding mode approach for induction motor drives direct torque and flux control. The proposed solution is composed by an integral sliding-mode control and by a speed-sensorless sliding mode observer. The suggested Integral Sliding-Mode Direct Torque Control (ISMDTC) is formulated in the stator flux reference frame, without employing current regulators. The adopted sliding...
This article presents a two-stage fault detection and classification scheme, for induction motor drives in wind turbine pitch systems. The presented approach is suitable for application in offshore wind farms. The adopted strategy utilizes three phase motor current sensing at the pitch drives for fault detection and only when a fault is detected at this stage, features extracted from the current signals...
An adaptive sliding-mode observer is proposed in this paper to update the rotor resistance in indirect field oriented controlled induction motor drives. Although the observer is implemented in stationary reference frame, the design and theory analysis are made in the rotor-field oriented reference frame. Through coordinate transformation, the essence of the sliding- mode manifold and the theory foundation...
A comprehensive dynamic modelling approach to evaluate efficiency and power losses in induction motor drive systems during both transient and steady-state working conditions is proposed in this paper. The developed dynamic model considers all the main loss contributions arising both from the power converter and the motor and permits the drive efficiency to be analysed, even separating each power loss...
This paper explores the possibility of using a nine-phase machine, with three isolated neutral points, in order to produce a high dc-link voltage by cascading three lower voltage three-phase voltage source inverters. Each inverter drives one winding set of the machine. Consequently, used inverter switches and capacitors have three times smaller voltage rating when compared to the single high-voltage...
Rotor time constant is a key parameter in an induction motor drive with indirect field oriented control. In this paper, a modified Model Reference Adaptive Controller (MRAC) utilizing d-axis stator voltage is proposed for online updating of rotor time constant. Compared with the traditional d-axis voltage model, the information of torque current and stator frequency is incorporated into the adaptive...
This paper investigates an ordinary least squares based indirect field oriented control (IFOC) of induction motor at very low speed range (1–5 rpm) using a low-count encoder. At very low speeds the speed estimation provided by common techniques for low-count encoder applications such as averaging the last two speed samples and/or considering the previous speed value until the next position update...
This paper addresses the method for total parameters identification in speed sensorless induction motor drives. By total parameters identification, it means that all the inverse-Γ circuit parameters are poorly known and need to be identified. Based on the parameter sensitivity, an alternating-current (AC) signal of medium frequency (25 Hz) is superimposed onto the stator magnetizing current, so that...
In this paper, artificial neural network assisted MRAS based speed estimator is presented for the poly-phase induction motor drive. The adaptive model of conventional RF-MRAS is replaced by a neural network in order to immune the system from rotor resistance variation and for the reduction of complex mathematical computational efforts. To train the network, Levenberg-Marquardt back-propagation algorithm...
This paper discusses application of Multilevel Inverter (MLI) in closed loop control of induction motor. This topology of MLI is called Nested topology which helps in reducing harmonics thereby increasing & improving the level and quality of voltages respectively. Proposed topology increases efficiency of output by reducing the losses effectively. The work mainly focuses on Matlab simulation and...
Position sensorless vector control drives in the rotor-flux-oriented reference frame require precise estimation of rotor flux. A few open-loop rotor flux estimation methods are quite popular. However, the performance of these estimators is quite poor when the inverter switching frequency is quite low as in case of high power drives or when the ratio of switching frequency to maximum fundamental frequency...
Predictive torque control (PTC) is a kind of finite control set model predictive control (FCSMPC) technique and this method is one of the widely used modern control techniques for induction motor drives. This control method becomes popular due to its simple structure, fast dynamic response and ability to include additional constraints (control parameters) into the objective function of the control...
Fault diagnostic index is a quantity which is sensed or calculated in order to diagnose and quantify the extent of fault. With increasing use of closed loop drives in industrial applications, online fault diagnosis has become a critical requirement. This paper focusses on exploring the average error in torque as a fault diagnostic index in field-oriented-controlled induction motor drives with stator...
The main objective of this paper is to implement solar powered speed sensorless vector control of induction motor drive for water pumping. The technique being used for speed estimation is a model reference adaptive system (MRAS). The MRAS speed sensorless technique is also used for motor parameters adaptation viz. stator resistance (Rs) and rotor time constant (Tr). The main objectives served by this...
In sine-triangle (ST) pulse width modulation (PWM), the carrier frequency is chosen to be an odd-triplen multiple (e.g., 3, 9, 15… etc.) of the modulating signal frequency in order to maintain the three-phase symmetry among the three pole voltages. However, for ST PWM with non-triplen pulse numbers (e.g., 5, 7, 11… etc.), the three-phase symmetry is not maintained. This paper studies the influence...
The paper deals with the fault tolerant Direct Field Oriented Control (DFOC) of an induction motor drive. Influence of the stator current sensor faults to the properties of the DFOC drive system is presented. To the current sensor fault detection the simple algorithmic/logical mechanism, based on the measured currents is used. After the fault detection, drive topology is changed. For the calculation...
Considering the disadvantages of induction motor drive such as torque ripple and current waveform distortion when using direct torque control (DTC) method, the method substitution might improve the drive behaviour. The authors suggest instead of the DTC method using the predictive method based on similar principles. In the paper, both methods are examined. Then on the induction motor drive yet controlled...
Finite control set model predictive control (FCS-MPC) is one of the promising alternatives for classical controllers (PID, hysteresis, etc…) in electric drive applications. The inherent discrete nature of FCS-MPC is suitable for a converter fed direct torque control (DTC) of induction motor drive. This paper presents a comparative study between conventional DTC and finite control set model predictive...
In most cases, using of an optical sensor represents the most common solution to obtain the induction motor actual speed. As in some cases the use of the speed sensor carries number of problems, an effort to find a solution that does not require a speed sensor is obvious in recent time. The paper presents some results of employing MRAS (Model Reference Adaptive System) method for sensorless induction...
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