6,738 research outputs found

    Random Zero Vector Distribution PWM Algorithm for Direct Torque Control of Induction Motor Drive for Noise Reduction

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    The basic direct torque control algorithm gives large ripples in torque, flux and current in steady state, which results in acoustical noise and incorrect speed estimations. The conventional SVPWM algorithm gives good performance for control of induction motor drive, but it produces more acoustical noise resulting in increased total harmonics distortion. The random pulse width modulation (RPWM) techniques have become an established means for mitigation of undesirable side effects in adjustable speed ac drives in particular. Hence, to minimize these anomalies of the drive, this paper presents a random zero vector distribution (RZVDPWM) algorithm for direct torque controlled induction motor drive. The proposed random zero vector distribution PWM (RZVDPWM) algorithm distributes the zero state time between the two zero voltage vectors. To validate the proposed PWM algorithm, simulation studies have been carried out and results are presented and compared. From the results, it can be observed that the proposed RZVDPWM algorithm gives reduced acoustical noise when compared with space vector pulse width modulation (SVPWM) algorithm

    BEZPOŚREDNIE STEROWANIE MOMENTEM WIELOFAZOWEGO SILNIKA INDUKCYJNEGO Z ROZMYTYM REGULATOREM PRĘDKOŚCI

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    The paper presents the Direct Torque Control with Space Vector Modulation (DTC-SVM) of seven-phase induction motor with Fuzzy Logic Speed Controller. The mathematical model of the seven-phase squirrel-cage induction motor and chosen methods of Space Vector Modulation have been presented. Simulation studies of the DTC-SVM with Fuzzy Logic speed controller have been carried out and the results of simulation studies have been presented and discussed. The author original contribution includes analysis and studies of considered control method of seven-phase induction motor.W artykule przedstawiono metodę bezpośredniego sterowania momentem siedmiofazowego silnika indukcyjnego z zastosowaniem metod modulacji wektorowej i rozmytego regulatora prędkości. Przedstawiono model matematyczny siedmiofazowego silnika indukcyjnego klatkowego oraz wybrane metody modulacji wektorowej. Przeprowadzono badania symulacyjne sterowania silnikiem z zastosowaniem metody DTC-SVM i rozmytego regulatora prędkości. Przedstawiono i omówiono wyniki badań symulacyjnych. Oryginalny wkład autora dotyczy analizy i badań przedstawionej metody sterowania silnikiem siedmiofazowym

    Simple speed sensorless DTC-SVM scheme for induction motor drives

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    The paper focuses on the development of a novel DSP based high performance speed sensorless control scheme for PWM voltage source inverter fed induction motor drives. Firstly, two generic torque and flux control methods the Field Oriented Control (FOC) and Direct Torque Control (DTC), are briefly described. For implementation the sensorless scheme DTC with Space Vector Modulation (DTCSVM) has been selected because it eliminates the disadvantages associated with the DTC while keeping the advantages of both FOC and DTC. Secondly, the simple flux vector observer allowing speed sensor elimination is given. The novelty of the presented system lays in combining the DTC-SVM structure with a simple observer for both torque/flux and speed sensorless control. Furthermore, the DTC-SVM structure which operates in speed sensorless and torque control mode is presented. Finally, the description of a 50 kW laboratory drive and experimental results illustrating properties of the system are given

    Direct Torque Control of Five-Phase Induction Motor Using Space Vector Modulation with Harmonics Elimination and Optimal Switching Sequence

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    In this paper an effective direct torque control (DTC) for a 5-phase induction motor with sinusoidally distributed windings is developed. First by coordinate transformation, the converter/motor models are represented by two independent equivalent d-q circuit models; and the 5-phase VSI input are decoupled into the torque producing and non-torque producing harmonics sets. Then with the torque production component of the induction motor model, the space vector modulation (SVM) can be applied to the five-phase induction motor DTC control, resulting in considerable torque ripple reduction over the lookup table method. Based on the decoupled system model, the current distortion issue due to lack of back EMF for certain harmonics is analyzed. Two equally effective SVM schemes with the harmonic cancellation effect are introduced to solve this problem. To analyze the DTC control torque ripple, an insightful perspective (also applicable to 3-phase analysis) is introduced to predict the torque ripple pattern evolution with changing motor speed and stator flux angular position. Therefore the switching sequence for lowest torque ripple can be determined and re-arranged online. Finally, with the overall optimal switching scheme adopted, detailed simulations verify the effectiveness of the new control

    Performance enhancement of direct torque control induction motor drive using space vector modulation strategy

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    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.Мета. Основна мета даної роботи – продемонструвати переваги використання методу модуляції просторового вектора при прямому регулюванні крутного моменту асинхронного двигуна. Для досягнення цієї мети запропоновано два різних підходи до прямого управління крутним моментом (з модуляцією просторового вектора), які досліджуються з порівняльної точки зору  одного з іншим, а також зі звичайним прямим керуванням крутним моментом. Новизна роботи полягає у використанні інтегрально-пропорційного (IП) регулятора швидкості в двох запропонованих підходах до прямого регулювання крутного моменту та більш поглибленій оцінці їх ефективності, головним чином, частоти перемикань напівпровідникових компонентів інвертора та пульсації крутного моменту двигуна. Методи. Два різних підходи до прямого керування крутним моментом, які використовують стратегію модуляції просторового вектора та/або керування нечіткою логікою, детально описані та змодельовані за допомогою ІП-регулятора швидкості. Обчислювальні експерименти проводяться з використанням програмного забезпечення Matlab/Simulink та/або інструментів нечіткої логіки. Результати. Практична цінність. Результати порівняння показують, що дві запропоновані структури прямого керування крутним моментом (з модуляцією просторового вектора) демонструють значне зниження пульсації крутного моменту, а також можуть уникнути проблеми випадкових змін частоти перемикання (у широкому діапазоні регулювання швидкості або крутного моменту). З іншого боку, використання ІП-регулятора швидкості забезпечило хороші динамічні характеристики для приводної системи, а також значно знизило пікове перевищення швидкості. Практично всі ці переваги досягаються при збереженні простоти та найкращих динамічних характеристик класичного прямого керування крутним моментом, особливо з модифікованим підходом прямого керування крутним моментом, при якому проектування або впровадження вимагає мінімальних обчислювальних витрат

    Investigation of traction motor control systems for electric vehicle applications.

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    Masters Degree. University of KwaZulu-Natal, Durban.Electric vehicles are a promising solution to the current pollution and greenhouse gas issues faced by the transport sector. As such, the traction motor control system of an electric vehicle is worthy of investigation. Direct torque and indirect field-oriented control are commonly applied control techniques, enabling advanced control of the induction and permanent magnet synchronous motors currently used in most electric vehicles being produced. Various improvements have been made to current traction motor control schemes to reduce ripple, improve parameter insensitivity, and increase powertrain efficiency. Consequently, the objective of the research conducted is to contribute to the field of electric vehicle powertrains through comprehensive investigations into the suitability and performance of direct torque and indirect field-oriented control in the traction motor control system of an electric vehicle. A four-stage simulation-based investigation was undertaken, with five motor control techniques initially assessed, which were conventional direct torque and field-oriented control, two space vector modulation-based direct torque control systems and fuzzy logic-based direct torque control. Results from the first stage of the simulation-based study highlighted expected issues with conventional direct torque control and showed that fuzzy logic-based direct torque control and space vector modulational-based direct torque control with closed-loop torque and flux control present promising solutions for use in the traction motor control system of an electric vehicle. Extensions of the simulation-based investigation in stages two and three included the integration and assessment of field-weakening control and sensorless speed estimation. Furthermore, stage four concluded the investigation with an essential analysis of a complete control mechanism in realistic urban and highway driving conditions. The fourth stage utilised sections of the New York City Cycle and Highway Fuel Economy Test cycle, with a simulated vehicle load. The complete study indicated that space vector modulation-based direct torque control with closed-loop torque and flux control performs suitably for electric vehicle applications, providing favourable speed, torque, current and stator flux results with a faster computation time than some comparable control options. The comprehensive investigation extends current literature and forms a basis for further investigation in the field of traction motor control systems for electric vehicle applications

    Study of Induction motor drive with Direct Torque Control scheme and Indirect Field Oriented control scheme with Space Vector Modulation

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    Induction motors are the starting point to design an electrical drive system which is widely used in many industrial applications. In modern control theory, different mathematical models describe induction motor according to the employed control methods. Vector control strategy can be applied to this electrical motor type in symmetrical three phase version or in unsymmetrical two phase version. The operation of the induction motor can be analyzed similar to a DC motor through this control method. With the Joint progress of the power electronics and numerical electronics it is possible today to deal with the axis control with variable speed in low power applications. With these technological projections, various command approaches have been developed by the scientific community to master in real time, the flux and the torque of the electrical machines, the direct torque control (DTC) scheme being one of the most recent steps in this direction. This scheme provides excellent properties of regulation without rotational speed feedback. In this control scheme the electromagnetic torque and stator flux magnitude are estimated with only stator voltages and currents and this estimation does not depend on motor parameters except for the stator resistance. In this dissertation report conventional DTC scheme has been described. Induction motor has been simulated in stationary d-q reference frame and its free acceleration characteristics are drawn. Conventional DTC scheme has been simulated with a 50 HP, 460V, 60Hz induction motor. Literature review has been done to study the recent improvements in DTC scheme which somehow is able to overcome the drawbacks of conventional one. The space vector modulation technique (SVPWM) is applied to 2 level inverter control in the vector control based induction motor drive system, thereby dramatically reducing the torque ripple. Later in this project space vector PWM technique will be applied to DTC drive system to reduce the torque ripple. I

    Analysis of Induction Motor Drive With Direct Torque Control Scheme Using Space Vector Modulation

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    Direct torque control (DTC) is one in all the foremost wonderful management methods of torque control of the induction motor. The aim is to regulate effectively the torque and flux. Torque control of associate induction motor (IM) supported DTC strategy is a developed and a comprehensive study which is made during this project. Direct torque management is that the 1st technology to regulate the important control variables of torque and flux. This methodology makes the rotor more accurate and quick management, high dynamic speed response and easy to regulate. The reference value may be calculated by the flux and torsion estimation and conjointly motor parameters. With the joint progress of numerical electronics and power electronics, it's potential nowadays to subsume the axis management with variable speed in applications involving low power. With these projections of technology, various command approaches are developed by the scientists to master in real time, the torque and also the flux of the electrical ac machines, the direct torque control (DTC) theme being one in all the foremost recent steps during this direction. This theme provides excellent regulation properties without using rotational speed feedback. During this control theme the electro- magnetic torque and mechanical device (stator) flux magnitude are calculable with solely mechanical device voltages and currents and this estimation doesn't rely upon motor parameters apart from the mechanical device (stator) resistance. In this thesis, typical DTC theme has been delineated. The induction motor (IM) has been simulated in stationary d-q arrangement and its free running acceleration characteristics are drawn. Typical DTC theme has been simulated with a two hundred horse power (200 HP), 460V, 60Hz induction motor. The literature review has been done to review the latest advancements in DTC theme that in someway is ready to beat the drawbacks of the typical one. The space vector modulation technique (SVM) is applied during this project to two level electrical converter (inverter) within the direct torque management primarily based on induction motor drive system. Space vector PWM methodology may be applied as future work to DTC drive system to cut back the torque (torsion) ripple

    Performance Analysis of DTC-SVM Sliding Mode Controllers-Based Parameters Estimator of Electric Motor Speed Drive

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    This paper is concerned with a framework which unifies direct torque control space vector modulation (DTC-SVM) and variable structure control (VSC). The result is a hybrid VSC-DTC-SVM controller design which eliminates several major limitations of the two individual controls and retains merits of both controllers. It has been shown that obtained control laws are very sensitive to variations of the stator resistance, the rotor resistance, and the mutual inductance. This paper discusses the performances of adaptive controllers of VSC-DTC-SVM monitored induction motor drive in a wide speed range and even in the presence of parameters uncertainties and mismatching disturbances. Better estimations of the stator resistance, the rotor resistance, and the mutual inductance yield improvements of induction motor performances using VSC-DTC-SVM, thereby facilitating torque ripple minimization. Simulation results verified the performances of the proposed approach

    A Study on the Sensorless Speed Control of Induction Motor by an Improved Direct Torque Control Technique

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    Recent years, there is a great increase in application of Field Oriented Control(FOC) for speed and torque of industrial induction motor drives. This trend can be seen in various industries like Steel, paper and also various machinery tools etc. Among the various method of drive controls, Direct Torque Control (DTC) and Vector Control are considered most high performance induction motor drives. An induction motor based on DTC is being increasingly used in various industrial applications. DTC offers faster torque response, better speed control and lesser hardware costs in compared with vector controlled drives. However, the conventional DTC suffers from high torque ripple, current harmonics and low performance during torque transients. In this paper, an improved direct torque control technique of induction motor is presented. In comparison with the conventional DTC technique, a well-developed Space Vector Modulation(SVM) technique is applied for more accurate current control. The torque and flux magnitude are under control using each PI controller, thereby generating the voltage command for inverter control. To control the speed and torque for induction motor, the system usually necessitates an information of speed or flux of the motor. However, there are many problems in case of using speed or flux sensors. A sensor requires a mounting space on the motor, reduces the reliability, and increases cost of the drive system. Therefore the various sensorless control algorithms have been proposed for the elimination of speed or flux sensors. For most of those sensorless methods, the control performance in high speed range is good, but it is difficult to obtain satisfactory result in low speed region. This paper presents sensorless speed control system for induction motor drive with an improved DTC method. The system consists of closed loop stator flux and torque controller, speed and torque estimators, PI controllers, PWM(Pulse width modulation) technique, IGBT(Insulated gate bipolar transistor) voltage source inverter, and micro-processor. The motor speed is estimated by using differential operator based on flux calculator. The simulation and experimental results based on an improved DTC technique indicated good speed and load response from the low speed range to the high speed range. The torque and speed ripple could be reduced in comparison with the conventional switching table DTC method.1. 서론 = 1 1.1 연구배경 및 동향 = 1 1.2 연구 목적과 구성 = 4 2. 유도전동기의 수학적 모델 및 제어기법 = 6 2.1 유도전동기의 전압방정식 = 6 2.1.1 3상 좌표계에서의 유도전동기 전압방정식 = 7 2.1.2 동기 회전좌표계에서의 유도전동기 전압방정식 = 11 2.2 벡터제어 = 16 2.2.1 직접벡터제어 = 17 2.2.2 간접벡터제어 = 19 2.3 직접토크제어 = 24 2.3.1 직접토크제어 알고리즘 = 24 2.3.2 직접토크제어의 기본 개념과 이론 = 27 3. 유도전동기 센서리스 속도제어 방식 = 34 3.1 속도추정기에 의한 방식 = 34 3.2 모델기준적응제어에 의한 방식 = 36 3.3 칼만필터에 의한 방식 = 38 3.4 슬롯고조파 분석에 의한 방식 = 40 3.5 상태궤환 선형화 기법에 의한 방식 = 42 3.6 신경회로망을 이용한 방식 = 47 3.7 고주파 신호주입을 이용한 방식 = 50 4. 개선된 직접토크제어방식에 의한 센서리스 속도제어 시스템 = 54 4.1 공간벡터 PWM 전류제어기 = 54 4.2 제어 알고리즘 = 62 4.3 기존 직접토크제어방식과 개선된 직접토크제어방식 비교 = 65 5. 컴퓨터 시뮬레이션 = 73 5.1 개선된 직접토크제어방식의 시뮬레이션 = 73 5.2 시뮬레이션 결과 검토 = 75 6. 실험장치의 구성과 실험결과 = 79 6.1 구동시스템의 하드웨어 구성 = 79 6.2 실험결과 및 검토 = 84 7. 결론 = 90 참고문헌 = 9
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