Induction Machine in Electric Drives

This paper presents a new configuration for direct torque control (DTC) of six-phase induction motor (SPIM). In the proposed method, direct torque and flux control are applied to the SPIM using matrix converter with the conventional three-phase source as its input. The new DTC scheme for SPIM benefits the advantages of both DTC and matrix converter. The simulation results show the effectiveness of the proposed method in both dynamic and steady state response.

This article proposes a new approach for direct torque control of induction motors. This method is based on direct torque control with pulse width modulation of a current source inverter using SIMULINK/MATLAB simulators for its performance assessment. The proposed control system is realized based on stator-flux-oriented reference. It uses the same method as direct torque control drive systems with a voltage source inverter to estimate the stator flux and electromagnetic torque and, therefore, only needs the stator resistance to control the motor. In this method, stator current components are calculated to directly control the stator flux and electromagnetic torque. Simulation results show the excellent performance of this system. Using simulations, the proposed method is also compared with the direct torque control voltage source inverter system, and it is shown that the proposed method improves induction motor performance and decreases the inverter switching losses. Another main advantage of the proposed control method is that it seriously limits the starting current and feeds the motor with high power quality. A novel switching method in space vector modulation of current source inverter is also proposed, which effectively decreases motor torque ripple and harmonic losses.

Direct Torque Control (DTC) of induction motor is a scalar control technique that gives excellent torque dynamic performance. Deriving the advantages of multilevel inverter, a modified DTC is proposed in this paper for the induction motor, driven by a cascaded three-level inverter. The proposed DTC gives superior torque performance compared to the use of Field Oriented Control (FOC) under transient conditions. The ruggedness of the proposed control scheme using the cascaded inverter is tested for speed change, speed reversal and also torque change commands. The envisaged DTC is simulated using Matlab/Simulink and experimentally validated using a laboratory prototype.

The Dynamic response of induction motor (IM) drive relies on control technique used. Field Oriented Control (FOC) and Direct Torque Control (DTC) are the two strategies to improve the dynamic performance of IM drives. For Electric Vehicles (EV’s) reduced ripples in torque and flux is required. This article, Introduces Predictive Torque Control (PTC) strategy for an Open-end Winding Induction Motor Drive (OWIMD) with four-level inversion by using selective voltage vectors to reduce torque ripples, flux ripples and computational burden on controller. The classical PTC (C-PTC) has the problem of high torque ripples, flux ripples, complex tuning of weighting factors and computational burden. This article utilizes the concept of reactive torque to eliminate weighting factor and flux sector information to apply selective voltage vectors. By using these two strategies, the proposed PTC algorithm will maintain less ripples and computational burden. To validate the proposed PTC, the obtained simulation results are compared with classical PTC.

PurposeThe direct torque control (DTC) of induction motor (IM) drive is featured by high ripples in the electromagnetic torque and stator flux profiles because they are controlled by two hysteresis regulators. Furthermore, the machine flux is not directly measurable. Hence, it is better to reconstitute it from the instantaneous electrical equations of the machine. Once the stator flux is estimated, we can guarantee a reliable sensorless DTC control. Thus, the purpose of this research work is to ensure fast response and full reference tracking of the IM under sensorless DTC strategy with desired dynamic behavior and low ripple levels.Design/methodology/approachIn this work, an improved DTC strategy, which is DTC_SVM_3L, is suggested. The first step of the designed approach is to substitute the conventional inverter feeding the motor with a three-level inverter because it guarantees reduced switching losses, improved quality of voltage waveform and low-current total harmonic distortion rate. The second aim of this paper is to make the IM operate at a constant switching frequency by using the nearest three vectors-based space vector modulation (SVM) technique rather than hysteresis controllers. The third objective of this study is to conceive a sliding-mode stator flux observer, which can improve the control performances by using a sensorless algorithm to get an accurate estimation, and consequently, increase the reliability of the system and decrease the cost of using sensors. The stability of the proposed observer is demonstrated based on the Lyapunov theory. To overcome the load change disturbance in the proposed DTC control strategy, this paper exhibits a comparative assessment of four speed regulation methods: classical proportional and integral (PI) regulator, fuzzy logic PI controller, particle swarm optimization PI controller and backstepping regulator. The entire control algorithm was tested under different disturbances such as stator resistance and load torque variations.FindingsIt was ascertained that the IM, controlled with three-level inverter, exhibits good performances under the proposed DTC-SVM strategy based on a sliding-mode observer. The robustness of the suggested approach against parameter variations is also proved.Originality/valueThe theoretical development of the proposed control strategy is thoroughly described. Then, simulations using Matlab/Simulink software are launched to investigate the merits of the sensorless DTC-SVM command of three-level inverter-fed IM drive with different speed regulators.

In modern high performance ac drives, field oriented control (FOC) or direct torque control (DTC) schemes are applied to achieve high dynamic operation. Recently, efforts have been made to eliminate the machine shaft sensor in order to reduce costs and increase reliability. Although DTC is often designated as a sensorless scheme, it has similar problems to FOC when operated around zero flux frequency. In this paper, the performance of both schemes is investigated with special emphasis on operation around zero speed. In that operating range it is assumed nowadays that, without a shaft sensor, the flux position can only be determined by exploiting parasitic effects of the machine such as saturation or slotting. Sensorless schemes to estimate the spatial flux position control suffer from reduced accuracy in specific load ranges which degrades the performance of the drive when compared to operation with a shaft sensor. On a test stand FOC and DTC have been realized and the flux position calculated with the use of a speed sensor has been modified with different error functions to test the reaction of both schemes on erroneous flux input values.

This work deals with the performance improvement study of the direct torque control (DTC) of induction Motor (IM) based on Fuzzy Second Order Sliding Mode Control (FSOSMC). Direct torque control using conventional Second Order Sliding Mode Control regulators has certain disadvantages such as significant flux, torque ripples and sensitivity to parametric variations. To overcome these drawbacks, we apply a new type with more robust regulators such as the fuzzy second order sliding mode control. In recent years, Ant Colony Optimization (ACO) algorithm have attracted considerable attention among various modern heuristic optimization techniques. This paper proposes the ant colony optimization algorithm with fuzzy second order sliding mode controller based direct torque control of induction motor to enhance the system performance and stability. Simulation results demonstrate the feasibility and validity of the proposed DTC-FSOSMC system by effectively accelerating system response, reducing torque and flux ripple and a very satisfactory performance has been achieved.KeywordsIMDTCFSOSMCACOParametric Uncertainties

In the induction motor speed control without sensors operated by the method Field Oriented Control (FOC) was required an observer to estimate the speed. Obsever methods have been developed, among others, was the method of Self-Constructing Fuzzy Neural Network (SCFNN) with some training algorithms such as backpropagasi (BP). Levenberg Marquard (LM) etc.. In the induction motor control techniques were also developed methods of Direct Torque Control (DTC) with observer Recurrent Neural Network (RNN). This paper compares the performance of the motor response to initial rotation between SCFNN observer method that uses the LM training algorithm with DTC control technique with RNN observer. From the observation performance of the motor response to initial rotation of the two methods shows that the LM method has better performances than the RNN. This can be seen on both the parameters : overshoot, rise time, settling time, peak and peak time. With the right method, can enhance better performance of the system. With the improvement of system performance, is expected to increase work efficiency in the industrial world, so overall, particularly for systems that require high precision, FNN methodcan be said to be better. Keywords: Motor Speed control without sensors, FOC, SCFNNO, DTC, Levenberg Marquardt and RNN. DOI: http://dx.doi.org/10.11591/ijpeds.v1i1.66

In this paper, a predictive direct torque control (DTC) of induction motor (IM) drive is presented. The control uses stator flux and current vectors as state variables. Predicted torque variation, with reference to its unforced response during each sampling time interval, is imposed with the aim of determining the pulse widths of the chain voltages of the supply inverter. The existence domain of the state variables in each sampling time interval is determined and depicted graphically. Inverter voltage saturation and current limitation constraints are also taken into account and shown graphically. The proposed control technique is employed in simulating a DTC IM drive by the Matlab Simulink tool. The simulation results, which are compared with those obtained by the traditional constant switching frequency DTC, highlight the good performance of the drive, especially referring to torque ripple and low-speed operation.

In this article, we present two techniques of commands DTC (direct torque control) and DPC (direct power control), applied to in the system for converting wind energy with storage. The use of the wind generator is based on a double fed induction Generator (DFIG) where the stator is connected directly to the network and the rotor is connected to the network through the power converter. The Flywheel Energy Storage System (FESS) based on a flywheel, an induction machine (IM) and an electronic power converter is associated with the wind generator via the DC bus. The two converters side DFIG and the (FESS) are controlled by the DTC. The three-level converter side electricity grid which ensures constant DC bus voltage is controlled by the DPC. In the literature, this control strategy has been frequently used for the two levels converter. The direct control of these systems has purpose to eliminate the block of pulse width modulation and loops of regulations internal controlled variables. The use of switching table makes the system more efficient from the technical and economic view.

This paper presents Artificial Neural Networks (ANN) and Adaptive Neural-Fuzzy Inference System (ANFIS) for reduction of torque and flux ripples in transient and steady state response of Direct Torque Control (DTC) for Induction Motor drive. The Flux and Electromagnetic torque can be controlled by using efficient Direct Torque Control (DTC) scheme This proposed technique is to improve the torque, speed and flux response with the Artificial Neural Network (ANN) and then with the Adaptive Neuro-Fuzzy Inference (ANFIS). This paper shows implementation of DTC system using ANN and ANFIS on three phase induction motor to optimize the flux and to improve the performance of fast stator flux response in transient state. To improve the performance of DTC with the modern technique using ANN and ANFIS approach is implemented and performance of ANN DTC compared with CDTC and ANN DTC with ANFIS is done, conclusion is about the ANN approach shows the better performance than CDTC and ANFIS shows superior performance than ANN. The performance has been tested by using MATLAB/SIMULINK and NEURAL NETWORK toolbox.

Compared with field orient control (FOC), direct torque control (DTC) is known to provide fast and robust response for induction motors. However, while offering high dynamic performance, classical DTC produces notable torque, flux, and current ripples, and operates with a variable inverter switching frequency. In this paper, a novel torque control scheme for induction motors is proposed. The stator flux and the electrical torque are directly controlled by variable-structure controllers, and stator voltage vectors calculated by the variable-structure controllers are applied to the motor by means of space vector modulation. The proposed scheme therefore provides smooth, fast and robust regulations of the electrical torque and the stator flux. Moreover, the implementation of the scheme is simple. Theoretical analysis shows the asymptotical convergence of electrical torque and stator flux tracking. Simulation and experimental results are provided to evaluate the performance of the proposed scheme.

This paper presents discrete space vector modulation (DSVM) based predictive torque control (PTC) of induction motor for Electric Vehicle (EV). In the conventional PTC, only seven voltage vectors are utilized for determination of flux and torque. In order to utilize the converter control region effectively without decreasing the sampling time of the controller and to decrease the ripple in the torque, flux and current, DSVM based PTC is applied for induction motor. According to the DSVM, each sampling time is divided into 3 equal parts and by applying standard voltage vectors totally 37 virtual voltage vectors are generated. These voltage vectors are used for flux and torque prediction. To decrease the computational burden of DSVM-PTC, number of voltage vectors used for the prediction is reduced by direct torque control (DTC) based sector selection method. The starting current of the motor is limited by a nonlinear function added in the cost function. The speed of the motor is estimated by rotor flux based speed estimation technique. Torque ripple, motor current THD are analysed and compared with conventional techniques in different modes of operation of the motor. The DSVM – PTC algorithm is evaluated in simulation and experimental platform, which gives excellent response even in low sampling frequency compared to conventional methods.

In this present paper, a decoupled method for a fixed switching frequency direct torque control (DTC) using four level inverter is discussed. In this approach the four level voltages are generated by using cascaded connection of two conventional two level inverters which are fed with the unequal dc link voltages. Controlling of the two inverters feeding the open end winding induction motor is easier than compared to the controlling of inverter voltages in the other multi level inverters. However, the proposed DTC scheme does not require the sector information of the estimated fundamental stator voltage vector and its relative position with respect to the stator flux vector. Simulation results clearly demonstrate a better dynamic and simplicity in numerical calculations of the proposed method.

If the common-mode voltage in the induction motor drive is not eliminated, it may cause failure of motor bearings and malfunctioning of the electrical equipment associated with the drive. This article proposes the modified direct torque control technique to control the induction motor fed by three-level inverter, commonly called a neutral-point-clamped inverter. The selective voltage vectors in three-level inverter determine elimination of the common-mode voltage. The classic three-level direct torque control based on selection of 6-full, 6-half, and 2-zero voltage vectors out of available 27 is modified so that the 6-intermediate voltage vectors and a zero voltage vector are employed. A comparative investigation with another three-level direct torque control method which reduces both common-mode voltage and torque ripple is also carried out. These methods are compared with classic two-level direct torque control method in context of common-mode voltage, torque ripple, current total harmonic distortion (THD) and DC-link utilization. The simulation and experimental results validate the proposed common-mode voltage elimination and common-mode voltage reduction direct torque control techniques.