Adaptive backstepping based online loss minimization control of an induction motor drive / by San Woo Nam.

The efficiency of an induction motor (IM) can be improved by the optimum selection of a flux level in the motor. Among the numerous loss minimization algorithms (LMA), a loss-model-based approach offers a fast response and no torque pulsation. However, it requires the accurate loss model and the knowledge of the motor parameters to find the optimum flux level. Therefore, a technical difficulty in deriving the loss-model-based LMA lies in the complexity of the full loss model and the on-line parameter adaptation for the precise motor parameters. In an effort to overcome the drawbacks of on-line loss model controllers (LMC), this thesis presents a new loss-model-based LMA for inverter-fed IM drives aiming at both high efficiency and high dynamic performance. A new LMC is proposed for the loss minimization of vector-controlled IM drives. An IM model in d-q coordinates is referenced to the rotor magnetizing current and then an iron loss resistance is added in parallel to the magnetizing inductance. This transformation leads to no leakage inductance on the rotor side by incorporating it into other parameters. This decomposition feature into d-q components makes the derivation o f the motor loss model and LMC simpler while keeping the effect of leakage inductances. In order to achieve high dynamic performance, an adaptive backstepping based nonlinear controller (ABNC) is designed incorporating iron loss under the parameter uncertainties of rotor resistance and load torque. In proposed IM equations, no additional state variables are added while iron loss is considered. Thus, an ABNC incorporating iron loss can be designed without much m ore complexity compared to the one with neglected iron loss. ABNC achieves desirable motor dynamics at any operating point while the flux level is varied by the LMC in order to reduce the input power. Adaptive backstepping technique provides a tool to design the controller avoiding wasteful cancellations of certain nonlinearities. Another important feature of an adaptive backstepping technique is that it can derive param eter update laws simultaneously with control laws from the error dynamics. With an extra gain introduced in adaptation laws design, we take advantage of this feature by combining the ABNC with LMC, thus an on-line param eter adaptation of LMC can be obtained with no extra effort. The complete closed loop control o f the proposed LMC based IM drive is implemented in real-time using digital signal processor board DS 1104 for a laboratory 1/3 hp motor. The dynamic performance of the proposed controller and parameter adaptation features are examined. The effectiveness of the proposed loss minimization scheme through a wide range of speed regions including the field weakening region is demonstrated through computer simulation and experimental results

Adaptive backstepping based nonlinear control of an interior permanent magnet synchronous motor drive

Permanent magnet synchronous machines (PMSM) have shown increasing popularity in recent years for industrial drive applications due to the recent developments in magnetic materials, power converters, and digital signal processors. In particular, Interior Permanent Magnet Synchronous Motor (IPMSM) drives are widely used in high performance drive (HPD) applications. Fast and accurate speed response and quick recovery of speed from any disturbances are essential. The control of a high performance permanent magnet synchronous motor drive for general industrial application has received wide spread interest of researchers. In this work, a novel speed and position control scheme for an IPMSM is developed based on a nonlinear adaptive control scheme. The vector control scheme is used to simplify control of the IPMSM. System model equations are represented in the synchronously rotating reference frame and provide the basis for the controller which is designed using the adaptive backstepping technique. Using Lyapunov’s stability theory, it is also shown that the control variables are asymptotically stable. The complete system model is developed and then simulated using MATLAB/Simulink software. Performance of the proposed controller is investigated extensively at different dynamic operating conditions such as sudden load change, command speed change, command position change and parameter variations. The results show the global stability of the proposed controller and hence found to be suitable for high performance industrial drive applications. The real time implementation of the complete drive system is currently underway

Robust control techniques for DFIG driven WECS with improved efficiency

Wind energy has emerged as one of the fastest growing renewable energy sources since mid-80‘s due to its low cost and environmentally friendly nature compared to conventional fossil fuel based power generation. Current technologies for the design and implementation of wind energy conversion systems (WECSs) include induction generator and synchronous generator based units. The doubly fed induction generator (DFIG) is chosen in this thesis because of its economic operation, ability to regulate in sub-synchronous or super-synchronous speed and decoupled control of active and reactive powers. Among the major challenges of wind energy conversion system, extraction of maximum power from intermittent generation and supervision on nonlinear system dynamics of DFIG-WECS are of critical importance. Maximization of the power produced by wind turbine is possible by optimizing tip-speed ratio (TSR), turbine rotor speed or torque and blade angle. The literature reports that a vast number of investigations have been conducted on the maximum power point tracking (MPPT) of wind turbines. Among the reported MPPT control algorithms, the hill climb search (HCS) method is typically preferred because of its simple implementation and turbine parameter-independent scheme. Since the conventional HCS algorithm has few drawbacks such as power fluctuation and speed-efficiency trade-off, a new adaptive step size based HCS controller is developed in this thesis to mitigate its deficiencies by incorporating wind speed measurement in the controller. In addition, a common practice of using linear state-feedback controllers is prevalent in speed and current control of DFIG-based WECS. Traditional feedback linearization controllers are sensitive to system parameter variations and disturbances on grid-connected WECS, which demands advanced control techniques for stable and efficient performance considering the nonlinear system dynamics. An adaptive backstepping based nonlinear control (ABNC) scheme with iron-loss minimization algorithm for RSC control of DFIG is developed in this research work to obtain improved dynamic performance and reduced power loss. The performance of the proposed controller is tested and compared with the benchmark tuned proportional-integral (PI) controller under different operating conditions including variable wind speed, grid voltage disturbance and parameter uncertainties. Test results demonstrate that the proposed method exhibits excellent performance on the rotor side and grid side converter control. In addition, the compliance with the modern grid-code requirements is achieved by featuring a novel controller with disturbance rejection mechanism. In order to reduce the dependency on system‘s mathematical model, a low computational adaptive network fuzzy interference system (ANFIS) based neuro-fuzzy logic controller (NFC) scheme is developed for DFIG based WECS. The performance of the proposed NFC based DFIG-WECS is tested in simulation to regulate both grid and rotor side converters under normal and voltage dip conditions. Furthermore, a new optimization technique known as grey wolf optimization (GWO) is also designed to regulate the battery power for DFIG driven wind energy system operating in standalone mode. In order to verify the effectiveness of the proposed control schemes, simulation models are designed using Matlab/Simulink. The proposed model for MPPT and nonlinear control of grid-connected mode and GWO based power control of standalone DFIG-WECS has been successfully implemented in the real-time environment using DSP controller board DS1104 for a laboratory 480 VA DFIG. The comparison among different controllers suggests that each control technique has its own specialty in wind power control application with specific merits and shortcomings. However, the PI controller provides fast convergence, the ANFIS based NFC controller has better adaptability under grid disturbances and ABNC has moderate performance. Overall, the thesis provides a detailed overview of different robust control techniques for DFIG driven WECS in grid-connected and standalone operation mode with practical implementation

Performance Analysis Of IPMSM Drive Using Fuzzy Logic Controller Based Loss Minimization Algorithm (LMA)

This project presents an online loss-minimization algorithm (LMA) for a fuzzy-logic-controller (FLC)-based interior permanent-magnet synchronous-motor (IPMSM) drive to yield high efficiency and high dynamic performance over a wide speed range. LMA is developed based on the motor model. In order to minimize the controllable electrical losses of the motor and thereby maximize the operating efficiency, the d-axis armature current is controlled optimally according to the operating speed and load conditions. For vector-control purpose, FLC is used as a speed controller, which enables the utilization of the reluctance torque to achieve high dynamic performance as well as to operate the motor over a wide speed range. In order to test the performance of the proposed drive in real time, the complete drive is experimentally implemented using DSP board DS1104 for a prototype laboratory 5-hp motor. The performance of the proposed loss-minimization-based FLC for IPMSM drive is tested in both simulation and experiment at different operating conditions. A performance comparison of the drive with and without the proposed LMA-based FLC is also provided. It is found from the results that the proposed LMA and FLC-based drive demonstrates higher efficiency and better dynamic responses over FLC-based IPMSM drive without LMA. In this project, an online LMA-based speed-control scheme of IPMSM drive incorporating an FLC has been presented. The LMA was developed based on the motor model

Development and implementation of various speed controllers for wide speed range operation of IPMSM drive / by Md Muminul Islam Chy.

Despite many advantageous features of interior permanent magnet synchronous motor (IPMSM), the precise speed control of an IPMSM drive becomes a complex issue due to nonlinear coupling among its winding currents and the rotor speed as well as the nonlinearity present in the electromagnetic developed torque due to magnetic saturation of the rotor core particularly, at high speeds (above rated speed). Fast and accurate response, quick recovery of speed from any disturbances and insensitivity to parameter variations are some of the important characteristics of high performance drive system used in robotics, rolling mills, traction and spindle drives. The conventional controllers such as PI, PID are sensitive to plant parameter variations and load disturbance. For the purpose of obtaining high dynamic performance, recently researchers developed several non-linear as well as intelligent controllers. Most of the reported works on controller design of IPMSM took an assumption of d-axis stator current (i[subscript d]) equal to zero in order to simplify the development of the controller. However, with this assumption it is not possible to control the motor above the rated speed and the reluctance torque of IPMSM can not be utilized efficiently. Furthermore, this assumption leads to an erroneous result for motor at all operating conditions. In this thesis, some controllers are developed for the IPMSM drive system incorporating the flux-weakening technique in order to control the motor above the rated speed. A detailed analysis of the flux control based on various operating regions is also provided in this thesis. In order to get the optimum efficiency, an adaptive backstepping based nonlinear control scheme incorporating flux control for an IPM synchronous motor drive is taken into account at the design stage of the controller. Thus, the proposed adaptive nonlinear backstepping controller is capable of conserving the system robustness and stability against all mechanical parameters variation and external load torque disturbance. To ensure stability the controller is designed based on Lyapunov's stability theory. A novel fuzzy logic controller (FLC) including both torque and flux control is also developed in this work. The proposed FLC overcomes the unknown and nonlinear uncertainties of the drive and controls the motor over a wide speed range. For further improvement of the FLC structure, the membership function of the controller is tuned online. An integral part of this work is directed to develop an adaptive-network based fuzzy interference system (ANFIS) based neuro fuzzy logic controller. In this work, an adaptive tuning algorithm is also developed to adjust the membership function and consequent parameters. In order to verify the effectiveness of the proposed IPMSM drive, at first simulation model is developed using Matlab/Simulink. Then the complete IPMSM drive incorporating various control algorithms have been successfully implemented using digital signal processor (DSP) controller board-DSI104 for a laboratory 5 hp motor. The effectiveness of the proposed drive is verified both in simulation and experiment at different operating conditions. The results show the robustness of the drive and it's potentiality to apply for real-time industrial drive application. This thesis also provides through knowledge about development and various speed real-time applications of controllers for IPMSM drive, which will be useful for researchers and practicing engineers

Commande par mode glissant de paliers magnétiques actifs économes en énergie : une approche sans modèle

Abstract : Over the past three decades, various fields have witnessed a successful application of active magnetic bearing (AMB) systems. Their favorable features include supporting high-speed rotation, low power consumption, and rotor dynamics control. Although their losses are much lower than roller bearings, these losses could limit the operation in some applications such as flywheel energy storage systems and vacuum applications. Many researchers focused their efforts on boosting magnetic bearings energy efficiency via minimizing currents supplied to electromagnetic coils either by a software solution or a hardware solution. According to a previous study, we adopt the hardware solution in this thesis. More specifically, we investigate developing an efficient and yet simple control scheme for regulating a permanent magnet-biased active magnetic bearing system. The control objective here is to suppress the rotor vibrations and reduce the corresponding control currents as possible throughout a wide operating range. Although adopting the hardware approach could achieve an energy-efficient AMB, employing an advanced control scheme could achieve a further reduction in power consumption. Many advanced control techniques have been proposed in the literature to achieve a satisfactory performance. However, the complexity of the majority of control schemes and the potential requirement of powerful platform could discourage their application in practice. The motivation behind this work is to improve the closed-loop performance without the need to do model identification and following the conventional procedure for developing a model-based controller. Here, we propose applying the hybridization concept to exploit the classical PID control and some nonlinear control tools such as first- and second-order sliding mode control, high gain observer, backstepping, and adaptive techniques to develop efficient and practical control schemes. All developed control schemes in this thesis are digitally implemented and validated on the eZdsp F2812 control board. Therefore, the applicability of the proposed model-free techniques for practical application is demonstrated. Furthermore, some of the proposed control schemes successfully achieve a good compromise between the objectives of rotor vibration attenuation and control currents minimization over a wide operating range.Résumé: Au cours des trois dernières décennies, divers domaines ont connu une application réussie des systèmes de paliers magnétiques actifs (PMA). Leurs caractéristiques favorables comprennent une capacité de rotation à grande vitesse, une faible consommation d'énergie, et le contrôle de la dynamique du rotor. Bien que leurs pertes soient beaucoup plus basses que les roulements à rouleaux, ces pertes pourraient limiter l'opération dans certaines applications telles que les systèmes de stockage d'énergie à volant d'inertie et les applications sous vide. De nombreux chercheurs ont concentré leurs efforts sur le renforcement de l'efficacité énergétique des paliers magnétiques par la minimisation des courants fournis aux bobines électromagnétiques soit par une solution logicielle, soit par une solution matérielle. Selon une étude précédente, nous adoptons la solution matérielle dans cette thèse. Plus précisément, nous étudions le développement d'un système de contrôle efficace et simple pour réguler un système de palier magnétique actif à aimant permanent polarisé. L'objectif de contrôle ici est de supprimer les vibrations du rotor et de réduire les courants de commande correspondants autant que possible tout au long d'une large plage de fonctionnement. Bien que l'adoption de l'approche matérielle pourrait atteindre un PMA économe en énergie, un système de contrôle avancé pourrait parvenir à une réduction supplémentaire de la consommation d'énergie. De nombreuses techniques de contrôle avancées ont été proposées dans la littérature pour obtenir une performance satisfaisante. Cependant, la complexité de la majorité des systèmes de contrôle et l'exigence potentielle d’une plate-forme puissante pourrait décourager leur application dans la pratique. La motivation derrière ce travail est d'améliorer les performances en boucle fermée, sans la nécessité de procéder à l'identification du modèle et en suivant la procédure classique pour développer un contrôleur basé sur un modèle. Ici, nous proposons l'application du concept d'hybridation pour exploiter le contrôle PID classique et certains outils de contrôle non linéaires tels que contrôle par mode glissement du premier et du second ordre, observateur à grand gain, backstepping et techniques adaptatives pour développer des systèmes de contrôle efficaces et pratiques. Tous les systèmes de contrôle développés dans cette thèse sont numériquement mis en oeuvre et évaluées sur la carte de contrôle eZdsp F2812. Par conséquent, l'applicabilité des techniques de modèle libre proposé pour l'application pratique est démontrée. En outre, certains des régimes de contrôle proposés ont réalisé avec succès un bon compromis entre les objectifs au rotor d’atténuation des vibrations et la minimisation des courants de commande sur une grande plage de fonctionnement

Disturbance/uncertainty estimation and attenuation techniques in PMSM drives–a survey

This paper gives a comprehensive overview on disturbance/uncertainty estimation and attenuation (DUEA) techniques in permanent magnet synchronous motor (PMSM) drives. Various disturbances and uncertainties in PMSM and also other alternating current (AC) motor drives are first reviewed which shows they have different behaviors and appear in different control loops of the system. The existing DUEA and other relevant control methods in handling disturbances and uncertainties widely used in PMSM drives, and their latest developments are then discussed and summarized. It also provides in-depth analysis of the relationship between these advanced control methods in the context of PMSM systems. When dealing with uncertainties,it is shown that DUEA has a different but complementary mechanism to widely used robust control and adaptive control. The similarities and differences in disturbance attenuation of DUEA and other promising methods such as internal model control and output regulation theory have been analyzed in detail. The wide applications of these methods in different AC motor drives (in particular in PMSM drives) are categorized and summarized. Finally the paper ends with the discussion on future directions in this area

Nonlinear control and perturbation compensation in UAV quadrotor

The great interest in the field of flying robotics encouraged a lot of research work to improve its control strategies. This thesis is about modelling and design of controllers and perturbation compensators for a UAV quadrotor. Four approaches are built in this purpose. The first approach is perturbation attenuation system in a UAV quadrotor. Hierarchical Perturbation Compensator (HPC) is built to compensate for system uncertainties, non-modelled dynamics and external disturbances. It comprises three subsystems designed to provide continuous and precise estimation of perturbation. Each subsystem is designed to avoid the drawbacks of the other. This approach has superior proficiency to decrease unknown perturbation either external or internal. The second approach is a Three Loop Uncertainties Compensator (TLUC), designed to estimate unknown time- varying uncertainties and perturbations to reduce their effects and in order to preserve stability. The novelty of this approach is that the TLUC can estimate and compensate for uncertainties and disturbances in three loops made to provide tracking to residual uncertainty in order to achieve a higher level of support to the controller. Exponential reaching law sliding mode controller is proposed and applied. It is integrated based on Lyapunov stability theory to obtain fast response with lowest possible chattering. The performance is verified through analyses, simulations and experiments. The third approach is Feedback Linearization based on Sliding Mode Control (FLSMC). The purpose is to provide nonlinear control that reduces the effect of the highly coupled dynamic behavior and the hard nonlinearity in the quadrotor. The proposed controller uses a Second Order sliding mode Exact Differentiator SOED to estimate the velocity and the acceleration. The fourth approach proposes an improved Non-Singular Terminal Super-Twisting Control for the problem of position and attitude tracking of quadrotor systems. The super-twisting algorithm is an effective control used to provide high precision and less chattering. The proposed method is based on a non-singular terminal sliding surface with new exponent that solves the problem of singularity in terminal sliding mode control. Design procedure and the stability analysis using Lyapunov theory are detailed for the considered approaches. The performance is verified through analyses, simulations and experiments

Torque Control

This book is the result of inspirations and contributions from many researchers, a collection of 9 works, which are, in majority, focalised around the Direct Torque Control and may be comprised of three sections: different techniques for the control of asynchronous motors and double feed or double star induction machines, oriented approach of recent developments relating to the control of the Permanent Magnet Synchronous Motors, and special controller design and torque control of switched reluctance machine

Robust adaptive nonlinear control of microgrid frequency and voltage in the presence of renewable energy sources

Global warming of the planet and air pollution have prompted an increased use of renewable energy sources for power generation. These new sources of clean energy are now very much in demand for setting up microgrids that provide energy independence to communities far from major urban centers. These microgrids should be able to operate either in isolated mode or to be connected to the main power grid. These requirements pose significant challenges. Indeed, in isolated mode, small and medium power grids are very sensitive to fluctuations in consumer power use as well as changes in the power produced by generators. In gridconnected mode, renewable energy sources do not contribute to the grid's stability and robustness as well as conventional generators do. Photovoltaic power plants pose some challenges when integrated with the power grid. The PV plants always focus on extracting the maximum power from the arrays. This makes the PV system unavailable for helping in regulating the grid frequency as compared to conventional generators. One of the main objectives of this research is to develop a robust adaptive nonlinear control technique which provides frequency regulation functionality to PV systems as well as voltage regulation. A small-scale power microgrid incorporating photovoltaic generators, synchronous generator and load is considered in our study. Dynamic models of the proposed microgrid were determined. The final model highlights the interactions between the sources of renewable energy and the rest of the network. A new robust adaptive nonlinear (exact input-output feedback linearization) control strategy was developed in order to meet the requirement of frequency regulation as well as voltage regulation. The new control strategy allows the PV system to have a similar response to changes in microgrid frequency as that of a conventional generator. The controller is also self-adjusting (adaptive) as well as robust in order to compensate the perturbation due to the changes in users’ power consumption, or any defects in the MG electrical network. The performance of the proposed solutions was evaluated in simulation using the Matlab/Simulink. For further verification, a small-scale laboratory experimental prototype of proposed microgrid was developed in laboratory to implement the proposed technique. This research may be regarded as an important basis for the development of microgrid power station for remote communities isolated from the main power system or large-scale power network with higher penetration of renewable energy sources