Torque Control Of Induction Motor Research Articles

Enhanced weighting factor selection for predictive torque control of induction motor drive based on VIKOR method

Predictive torque control (PTC) is one of the widely used modern control techniques for induction motor drives due to its merits such as; implementation is straightforward and direct inclusion of control parameters into the cost-function is possible. However, the main drawback of this technique is the selection of appropriate weighting factor in the cost-function. In this study an attempt is made to simplify the weighting factor selection by using VlseKriterijuska Optimizacija I Komoromisno Resenje (VIKOR) method and the cost function of PTC is modified accordingly. Usage of VIKOR method in the cost-function optimisation introduces the compromise ranking to select an optimal control action. Both simulation and experimental results are carried out for a two-level voltage source inverter fed induction motor drive with the proposed control technique and the results are compared with conventional PTC technique. These results confirm that proposed method retains the dynamic response achieved by the conventional PTC along with reduced torque ripple and switching frequency.

Sensorless Direct Torque Control of Induction Motor Using AI Based Duty Ratio Controllers

This paper presents some improvements in direct torque control of an induction motor using fuzzy logic switching controller along with fuzzy logic and neural network based duty ratio controller. The conventional direct torque control of induction motor suffers from major drawbacks like high torque and flux ripples, current and torque distortion when sector changes and poor transient response. High torque and flux ripples are reduced to some extent by replacing hysteresis controller and switching table with fuzzy logic switching controller (FDTC). However, in FDTC the selected switching vector is applied for the complete switching time period which results in ripples under steady state. The FDTC steady state performance is improved by using duty ratio controller. Using duty ratio controller, the selected switching vector is applied to voltage source inverter only for the time determined by the duty ratio (δ) and for the remaining time, a zero switching vector is applied. As the switching vector is applied for only the time period till torque reaches its reference value, it results in the reduction of torque and flux ripples of induction motor. The selection of duty ratio is a nonlinear function of flux error, flux error and stator flux angle which is effectively implemented in this paper using the following artificial intelligence techniques: fuzzy logic and neural networks. The effectiveness of the proposed methods are evaluated by the simulation with Matlab/Simulink.

A Simplified Finite-State Predictive Direct Torque Control for Induction Motor Drive

Finite-state predictive torque control (FS-PTC) is computationally expensive, since it uses all voltage vectors (VVs) available from a power converter for prediction and actuation. The computational burden is rapidly increased with the number of VVs and objectives to be controlled. Moreover, designing a cost function with more than two control objectives is a complex task. This paper proposes a simplified algorithm based on a new direct torque control (DTC) switching table to reduce the number of VVs to be predicted and objectives to be controlled. The new switching table also assists to reduce average switching frequency and its variation range. As a result, the cost function is simplified by not requiring to include the frequency term. Experimental results show that the average execution time and the average switching frequency for the proposed algorithm are greatly reduced without affecting the torque and flux performances achieved in the conventional FS-PTC.

Direct Torque Control of Induction Motor with Matrix Converter

Direct Torque Control of Induction Motor with Matrix Converter

Direct Torque Control of Induction Motor Drives

Direct Torque Control of Induction Motor Drives

A Novel Predictive Direct Torque Controller for Induction Motor Drives

A predictive direct torque controller (PDTC) for induction motors (IM) is proposed. It combines the direct torque control (DTC) and the predictive control (PC), and uses a predictive switching table to enhance the overall performance of the motor. A new type of PC is adopted for speed regulation with the use of a load torque observer, the torque being considered an unknown perturbation. A Kalman filter (KF) is used for reliable flux estimation. The validity of the proposed controller was experimentally confirmed on a rapid control prototyping station. The obtained results have proven superiority of the proposed control with respect to the speed trajectory tracking, torque and flux dynamic responses, and disturbance rejection. Also, a lower current distortion was observed with PDTC, in comparison with the regular DTC, due to increased mean inverter switching frequency.

Modeling and Simulation of Voltage Source Inverter with Voltage Drop and Its Application for Direct Torque Control of Induction Motors

Modeling and Simulation of Voltage Source Inverter with Voltage Drop and Its Application for Direct Torque Control of Induction Motors

Direct Torque Control of Induction Motor with Cascaded Multilevel inverter

3 Abstract: In this Paper, an Intelligent Direct Torque Control (DTC) method is proposed for controlling induction motor using Multilevel inverter with space Vector Modulation (SVM).A stage of Artificial Neural Network (ANN) is utilised for predicting the target parameters with the corresponding input parameters change in motor torque and flux. The change in motor torque and flux parameters are extracted from the behaviour of the system with PI controller. The back propagation learning method is used to learn the ANN. By using the ANN output and PI controller outputs, PWM control signal are generated from the SVM technique and control the multilevel inverter. Then the proposed intelligent control technique is implemented in the MATLAB/Simulink and the effectiveness are analysed with five level cascaded inverter and comparing the results with PI cont roller and the proposed case. The comparison results shows that the proposed method have good speed control response. Keyword: DTC, SVM, ANN, Multilevel inverter, Induction motor.

Model predictive torque control of induction motor drives with reduced torque ripple

Model predictive torque control (MPTC) is emerging as a high-performance control strategy for induction motor (IM) drives, due to its intuitive nature, flexibility to incorporate constraints and quick dynamic response. However, the implementation of MPTC requires high computational ability and the use of single voltage vector during one control period fails to reduce the torque ripple to the minimal value. This study proposes an improved MPTC for IM drives with reduced torque ripple and low complexity. On the basis of the relationship between stator current and stator flux, the complicated current prediction for each voltage vector is eliminated, reducing the control complexity significantly. Torque ripple reduction is achieved by allocating only a fraction of control period to the active vector selected from conventional MPTC, whereas the rest of time is allocated for a null vector. Two kinds of methods for optimising the duty ratio of the active vector are proposed and evaluated in detail. Presented experimental results prove that, compared with conventional MPTC, the proposed MPTC achieves better steady-state performance by reducing the torque ripple significantly. Meanwhile, the quick dynamic response of conventional MPTC is reserved.

High Performance Direct Torque Control for Induction Motor Drive Fed from Photovoltaic System

High Performance Direct Torque Control for Induction Motor Drive Fed from Photovoltaic System

FUZZY CONTROLLED DTC FED BY A FOUR SWITCH INVERTER FOR INDUCTION MOTOR

Direct Torque Control of induction motor fed drives has become popular and widely used in industries due to fast and good torque response. Induction motors (IM) are simple in construction and are less sensitive to the motor parameters compared to other vector control methods. The conventional DTC is based on flux and torque hysteresis controllers. Induction motor is fed from a Four Switch Inverter generating the voltage vectors of the Six Switch Inverter by reconfiguration. Applying the most optimized voltage vector that produce fastest dynamic torque response during transient states. Fuzzy logic concept is a most efficient artificial integilence method which has high application in electric motor drives. A method to achieve fastest dynamic performance by modifying the two leg inverter fed DTC of induction motor based on Fuzzy Logic Concept is used here. This paper presents a rule-based fuzzy logic controller scheme designed and applied for the speed control of an induction motor fed from a four switch three phase inverter emulating the six switch three phase inverter. Due to the usage of the Fuzzy logic concept, the reliability, efficiency and performance of ac drive increases. Initial torque peak and torque ripple are minimized in the four switch three phase inverter based DTC using Fuzzy Logic.

Direct torque control of induction motors fed by a single frequency converter

Direct torque control of an induction motor is established by survey of operation regimes of traction electric drives to thoroughly satisfy the requirements for a traction electric drive. The advantages and shortcomings of three-level voltage source inverters in locomotive traction electric drives are highlighted in relation to two-level ones. A mathematical model of a multimotor system fed by a single frequency converter based on direct torque control is developed. It is shown that the variables of an induction motor can be represented as the sum of its average value and deviation from it. The equations for stator flux linkage and torque of an induction motor have been developed for a two-motor system fed by a single voltage source inverter. The topology and principles of operation of direct torque control of induction motors with a three-level voltage source inverter are described. The simplified structure and mathematical model of the mechanical part of a traction drive using basic and axle suspension are considered. The results of simulation carried out by Matlab are shown.

A Review of the DTC Controller and Estimation of Stator Resistance in IM Drives

<span>In recent years an advanced control method called direct torque control (DTC) has gained importance due to its capability to produce fast torque control of induction motor. Although in these systems such variables as torque, flux modulus and flux sector are required, resulting DTC structure is particularly simplistic. Conventional DTC does not require any mechanical sensor or current regulator and coordinate transformation is not present, thus reducing the complexity. Fast and good dynamic performances and robustness has made DTC popular and is now used widely in all industrial applications. Despite these advantages it has some disadvantages such as high torque ripple and slow transient response to step changes during start up. Torque ripple in DTC is because of hysteresis controller for stator flux linkage and torque. The ripples can be reduced if the errors of the torque and the flux linkage and the angular region of the flux linkage are subdivided into several smaller subsections. Since the errors are divided into smaller sections different voltage vector is selected for small difference in error, thus a more accurate voltage vector is selected and hence the torque and flux linkage errors are reduced. The stator resistance changes due to change in temperature during the operation of machine. At high speeds, the stator resistance drop is small and can be neglected. At low speeds, this drop becomes dominant. Any change in stator resistance gives wrong estimation of stator flux and consequently of the torque and flux. Therefore, it is necessary to estimate the stator resistance correctly. This paper aims to review some of the control techniques of DTC drives and stator resistance estimation methods.</span>

Generalized Two-Vector-Based Model-Predictive Torque Control of Induction Motor Drives

Conventional single-vector-based model-predictive torque control (MPTC) has been widely studied owing to its intuitive concept and quick response. To improve the steady-state performance, recently, the concept of duty cycle control was introduced in MPTC by inserting a null vector along with an active vector during one control period. However, this still fails to reduce the torque error to a minimal value due to the imposed restriction on vector combination and the cascaded processing of vector selection and vector duration. This paper proposes a generalized two-vectors-based MPTC (GTV-MPTC) by relaxing the vector combination to two arbitrary voltage vectors. By evaluating the vector combination and their durations simultaneously in the predefined cost function, global minimization of torque error can be obtained in theory. However, the computational burden is also significantly increased. By choosing a proper method to determine the vector durations, the redundant vector combinations can be eliminated, which makes the proposed GTV-MPTC suitable for real-time implementation. Both simulation and experimental results were carried out to verify the effectiveness of the proposed method. The presented results show that, compared to prior MPTC with or without duty cycle control, the proposed GTV-MPTC achieves much better performance with lower sampling frequency over a wide speed range. Furthermore, the average switching frequency is even lower than that of conventional MPTC in the medium speed range.

English

In this paper, a new method is proposed to estimate the Stator Resistance for direct torque control of Induction Motor. Direct Torque control of Induction Motor (IM) requires accurate estimation of torque, flux angle and resultant flux and these signals in turn depends on the motor flux. The flux is generally estimated using voltage model equations. The voltage model equation to a large extent depends on the accuracy of stator resistance of the induction motor. The stator resistance varies due to temperature during motor operation. Hence a method based on the active and reactive power is proposed for stator resistance estimation. The effect of stator resistance variation on the flux, torque and flux angle is studied and the results obtained are presented. The proposed method of stator resistance estimation is shown to track the various %changes in stator resistance with good accuracy.

낮은 스위칭 주파수로 구동되는 유도전동기의 모델예측토크제어

When medium and large induction motors are driven by 2-level inverters with low switching frequency, induction motors provoke deteriorated performances resulted from large torque ripples, flux ripples, and large current distortion. Model predictive torque control(MPTC) for a fast torque control of induction motors is also suffered from large torque ripples when the induction motors are fed by 2-level inverters that are based on 6 active voltage vectors with low switching frequency restricted. To solve this problem, this paper proposes a new MPTC method based on both a 12 active voltage vector and an optimized duty ratio calculation. The proposed control strategy illustrates its effectiveness under the various operating conditions through simulation works.

FPGA-Based Implementation Direct Torque Control of Induction Motor

<p>This paper proposes a digital implementation of the direct torque control (DTC) of an Induction Motor (IM) with an observation strategy on the Field Programmable Gate Array (FPGA). The hardware solution based on the FPGA is caracterised by fast processing speed due to the parallel processing. In this study the FPGA is used to overcome the limitation of the software solutions (Digital Signal Processor (DSP) and Microcontroller). Also, the DTC of IM has many drawbacks such as for example; The open loop pure integration has from the problems of integration especially at the low speed and the variation of the stator resistance due to the temperature. To tackle these problems we use the Sliding Mode Observer (SMO). This observer is used estimate the stator flux, the stator current and the stator resistance. The hardware implementation method is based on Xilinx System Generator (XSG) which a modeling tool developed by Xilinx for the design of implemented systems on FPGA; from the design of the DTC with SMO from XSG we can automatically generate the VHDL code. The model of the DTC with SMO has been designed and simulated using XSG blocks, synthesized with Xilinx ISE 12.4 tool and implemented on Xilinx Virtex-V FPGA.</p>

Direct torque control of induction motor using three-level diode clamped inverter with DC-link capacitors voltage balancing

A simple switching table-based direct torque control of induction motor using three-level diode clamped inverter with DC-link capacitor voltage balancing is proposed in this paper. This scheme effectively utilises redundant states of small voltage vectors for charging and discharging of DC-link capacitors. The capacitor voltage balancing of the inverter is incorporated in the switching table of direct torque control. The switching table employed in this scheme balances the capacitor voltages for all operating conditions and it does not require any additional circuitry. To validate this scheme, extensive simulations are carried out for different load conditions. The steady state and transient operations of drive are investigated. The dynamics of DC-capacitor voltages are also tested. The results show that the proposed scheme provides capacitor voltage balancing and reduces neutral point drift voltage. The proposed scheme can be considered for medium and low voltage industrial drive applications.

Dynamic modeling of modular fuel cell for maximum power point tracking and torque ripple reduction in direct torque control of induction motor

This paper presents a comprehensive dynamic model of a proton exchange membrane fuel cell (FC) based on the electrical empirical model. The presented model is useful for online control as well as having suitable accuracy. FC stacks produce a DC voltage with a ratio of 2:1 in output from no-load to full-load. In vehicles that are equipped with FCs, the output voltage of the FC is drastically changed because the power and torque of the vehicle change with the driving cycle. In order to improve the performance of the direct torque control of induction motors, the modular structure of a FC is proposed. This proposed structure guarantees the maximum power point tracking and torque ripple reduction. The validity of the proposed structure is satised by simulation results using MATLAB/Simulink software.

Direct Torque Control of Induction Motor Using Three-Level Neutral Point Clamped Inverter

The direct torque control strategy of squirrel-cage induction motor using three-level neutral point clamped inverter is presented. The strategy used for controlling the torque of induction motor includes the change in applied voltage to the squirrel-cage induction motor .The variable voltage is provided with the help of look up table to the inverter. It is observed that the torque ripples are much in three-level inverter as compared to three level ineverter. This is because of the high dv/dt ratio of the output voltage of inverter. The current ripple produces torque ripples in steady state. The performance of motor in transient state and steady state are shown. The parameters of machine are given and the controlling strategy is performed using MATLAB/Simulink software. The control strategy is simulated on a 5 hp SQIM drive with three-level insulated-gate bipolar transistor (IGBT) inverter in MATLAB/Simulink software.