ANFIS Based Speed Controller for a Direct Torque Controlled Induction Motor Drive

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.

Purpose. The main objective of this work is to demonstrate the advantages brought by the use of space vector modulation technique in the direct torque control of the induction motor. To achieve this purpose, two different direct torque control approaches (with space vector modulation) are proposed and studied from a comparative aspect with each other and with the conventional direct torque control. The novelty of this work consists in the employment of an Integral-Proportional (IP) speed controller in the two proposed direct torque control approaches and a more in-depth evaluation for their performance mainly the switching frequency of inverter semiconductor components and motor torque ripples. Methods. Two different direct torque control approaches that use the space vector modulation strategy and/or fuzzy-logic control, are described in detail and simulated with IP speed controller. The simulation experiments are carried out using Matlab/Simulink software and/or fuzzy-logic tools. Results. Practical value. Comparison results show that the two proposed direct torque control structures (with space vector modulation) exhibit a large reduction in torque ripples and can also avoid random variation problem of switching frequency (over a wide range of speed or torque control). On the other hand, the use of IP speed regulator ensured good dynamic performance for the drive system as well as considerably minimized peak overshoot in the speed response. Practically all of these benefits are achieved while retaining the simplicity and the best dynamic characteristics of the classical direct torque control, especially with the modified direct torque control approach in which the design or implementation requires minimal computational effort.

This paper proposes 20-sector based direct torque control (DTC) scheme for dual inverter fed five phase induction motor drives with open-end stator windings powered by a single DC source. The proposed scheme utilizes 20 virtual voltage vectors that divide the space vector plane into 20 sectors, each sector spanning 18 degrees. The 20-sector based DTC scheme provides a smoother control over torque and flux compared to the conventional 10 sector-based DTC schemes for five phase induction motors. The switching scheme used in the proposed scheme eliminates the auxiliary plane harmonic voltages and provides higher DC bus utilization compared to two-level five phase voltage source inverter fed DTC schemes. The switching scheme for realization of these virtual voltage vectors does not generate any resultant common mode voltage across the stator windings and hence a single DC source is used to supply both the voltage source inverters. The proposed DTC scheme is validated by extensive simulation using MATLAB-Simulink software and experimentally verified on a laboratory prototype.

This paper presents a simplified self-tuned Sugeno type neuro fuzzy controller (NFC) based direct torque control (DTC) scheme for induction motor (IM) drive. A simple tuning algorithm is developed based on the reference and actual acceleration of the motor. The online tuning strategy adjusts the parameters of the consequent layer of the NFC in such a way to minimize the square of the error between actual and reference acceleration of the IM. In a conventional DTC scheme the band limits of flux and torque hysteresis controllers remain fixed and hence the torque and flux ripples are high. In order to optimize the torque ripples of the IM the hysteresis band limits are adjusted online for the torque hysteresis controller. In order to test the performance of the proposed NFC based DTC scheme for IM drive a complete simulation model is developed using MATLAB/Simulink. The proposed NFC based DTC scheme is implemented in real-time using DSP board DS1104 for a prototype 1hp squirrel cage IM. The performance of the proposed drive is tested at different operating conditions in both simulation and experiment.

Most of the direct and indirect torque control schemes proposed for switched reluctance motors (SRMs) consider equal rotor and stator pole arc. Leading to a linear non-saturating inductance profile. However, actually, in SRM, the rotor pole arc is kept higher than the stator pole arc. Leading to a non-linear saturating inductance profile. And not considering this in control leads to underutilization of the maximum torque producing capacity during the constant torque region. In the proposed novel direct torque control (DTC) scheme, firstly, the rotor pole arc and saturation effect are incorporated by considering it in the sector formation for every electrical cycle. Second, the flux control loop is removed, and sectors are classified based on the actual inductance profile, which is rotor position-dependent. Also, the voltage vector selection rule is modified for torque control. And the proposed voltage vector concerning the sector, allows multiple phases to conduct simultaneously. Wherein each phase conducts according to its actual inductance profile. This also ensures complete energization of incoming phase current while the outgoing phase is maintained at a constant current level. Leading to a reduction in torque ripples during commutation. The proposed DTC scheme incorporating the rotor pole arc and saturation effect improves the operating range for effectively reducing the torque ripples and facilitates a higher torque/ampere ratio.

This paper investigates the performance of a novel direct torque control (DTC) strategy dedicated to interior permanent magnet (IPM) brushless AC (BLAC) motor drives. The proposed strategy is based on a dual control approaches, consisting in: (i) a conventional DTC strategy where the control laws are inspired from the earlier Takahashi DTC strategy implemented in induction motor drives, and (ii) the bus-clamping (BC) strategy recently-introduced for the control of voltage source inverters, yielding the so-called “bus-clamping DTC” (BC-DTC). It consists in the synthesis of two vector selection tables depending on the rotation direction, in such a way to clamp each motor phase during 60°-interval in every half cycle of the reference stator flux vector. A simulationbased comparative study between the performance of the introduced BC-DTC and the conventional one, considering appropriate criteria, has highlighted the superiority of the proposed strategy which exhibits lower inverter switching losses, reduced harmonic distortion of the motor phase currents and damped torque ripple in a wide speed range.

Parameter sensitivity analysis of Direct Torque Control(DTC) scheme for dual inverter fed open end winding induction motor drive with single DC source is presented in this paper. The effect of stator resistance variation on the voltage vector selection in this DTC scheme is analysed using the voltage space structure of a dual inverter configuration with single DC source. Theoretical analysis is validated by simulation on a MATLAB Simulink platform. The results of the theoretical and simulation analyses are experimentally verified on an induction motor with open-end stator windings using TMS320F28335 digital signal processor.

A virtual voltage vector based direct torque control (DTC) scheme with enhanced resolution for five-phase induction motor (IM) drives with open-end stator windings, fed by two inverters, is proposed in this article. In the proposed scheme, the voltage space vector plane is divided into 20 sectors, by using 40 virtual voltage vectors produced as resultants of the virtual voltage vectors of the individual inverters thereby substantially increasing the sector resolution compared to the 10-sector based conventional five-phase DTC schemes. This DTC scheme incorporates a five-level hysteresis comparator for torque control and the required voltage vectors of different magnitudes are produced by appropriately combining the vectors of the two inverters. The increased sector resolution along with five-level hysteresis torque controller facilitates finer flux and torque control. As the effective common mode voltage in the motor windings is made zero in every switching period, both inverters can be connected to a common dc supply without causing circulation of zero sequence current. The proposed scheme is validated by performing experiment on a five-phase IM drive.

In order to reduce torque ripple of direct torque control (DTC) scheme, a novel stator flux reference optimize strategy is introduced first in this paper. Then, a fuzzy logic controller is designed to select synthesized voltage vectors. Three inputs of the fuzzy controller are the error of electromagnetic torque and the error of square stator flux linkage between the reference value and actual value and torque angle. The output of the fuzzy controller is corresponding voltage vector. The proposed control scheme is verified by simulations. Simulation results show that a reduction of torque ripples is achieved in a whole speed range.

A new hybrid fuzzy controller for direct torque control (DTC) induction motor drives is presented in this paper. The newly developed hybrid fuzzy control law consists of proportional-integral (PI) control at steady state, PI-type fuzzy logic control at transient state, and a simple switching mechanism between steady and transient states, to achieve satisfied performance under steady and transient conditions. The features of the presented new hybrid fuzzy controller are highlighted by comparing the performance of various control approaches, including PI control, PI-type fuzzy logic control (FLC), proportional-derivative (PD) type FLC, and combination of PD-type FLC and I control, for DTC-based induction motor drives. The pros and cons of these controllers are demonstrated by intensive experimental results. It is shown that the presented induction motor drive is with fast tracking capability, less steady state error, and robust to load disturbance while not resorting to complicated control method or adaptive tuning mechanism. Experimental results derived from a test system are presented confirming the above-mentioned claims.

This paper presents a direct torque control (DTC) scheme for matrix converter driven induction motor. The proposed scheme uses the simplified carrier-based PWM scheme of matrix converter for generation of PWM voltages. The proposed DTC scheme is characterized by the advantages of simple structure, unity input power factor operation of matrix converter, minimum torque ripple, and uniform switching as with carrier based modulation. A speed sensorless closed loop speed control of the induction motor is implemented along-with the DTC scheme. The novel carrier based modulation method is used to generate the PWM voltages from the matrix converter

A review of reliable and energy efficient direct torque controlled induction motor drives

A method for reducing torque pulsation in direct torque controlled induction motors is proposed, based on a switching update rate which is higher than the rated power device switching rate, but which does not over-switch the devices.

The paper is devoted to the synthesis and performance analysis of a direct torque control (DTC) strategy, based on the bus-clamping technique, dedicated to three level NPC inverter fed induction motor drives. The principle of the proposed strategy consists in keeping the voltage vector of each motor phase during 60° of the half of a cycle of the reference stator flux vector. The synthesis of the vector selection tables (one for clockwise rotation and the other for anti-clockwise rotation) is achieved on the basis that enables the fulfilment of the control combinations related to the variations of the stator flux and the electromagnetic torque, along with a reduction of their ripples. Simulation results highlight the torque high dynamic as well as reduced ripple, exhibited by the three level NPC inverter fed induction motor drive under the control of the proposed bus-clamping DTC strategy.

In the traditional direct torque control (DTC) of induction motor, the low order harmonic component of stator current is very large when the motor is running at low speed. It leads to high torque ripple of motor in low speed. To solve this problem, a new control method has been proposed in this paper. Base on the traditional DTC method, electromagnetic torque and flux models have been analyzed. To further improve the torque response and reduce the torque ripple, fuzzy logic concept has been introduced into the flux model. The method of dynamic adjustment of the torque hysteresis amplitude is proposed. In this model, fuzzy variables are the speed and stator current error. Through the rationalization of fuzzy classification, the choice of voltage space vector is optimized. The results of simulation and experiment show that the method can not only improve the speed of torque response, and the problem of torque ripple can be effectively solved. In the whole speed range, the performance of dynamic and static is better than that of the conventional DTC.