Accurate Inverter Error Compensation and Related Self-Commissioning Scheme in Sensorless Induction Motor Drives

This paper presents a technique for accurately identifying and compensating the inverter nonlinear voltage errors that deteriorate the performance of sensorless field-oriented controlled drives at low speed. The inverter model is more accurate than the standard signum-based models that are common in the literature, and the self-identification method is based on the feedback signal of the closed-loop flux observer in dc current steady-state conditions. The inverter model can be identified directly by the digital controller at the drive startup with no extra measures other than the motor phase currents and dc-link voltage. After the commissioning session, the compensation does not require to be tuned furthermore and is robust against temperature detuning. The experimental results, presented here for a rotor-flux-oriented SFOC IM drive for home appliances, demonstrate the feasibility of the proposed solution

Gain Scheduling of a Full-Order Observer for Sensorless Induction Motor Drives

This paper deals with the design of a speed-adaptive full-order observer for sensorless induction motor (IM) drives. A general stabilizing observer gain matrix, having three free design parameters, is used as a design framework. A gain-scheduled selection of the free design parameters is proposed. Furthermore, the full-order observer is augmented with the stator-resistance adaptation, and the local stability of the augmented observer is analyzed. The performance of the proposed full-order observer design is experimentally compared with a reduced-order observer using a 2.2-kW IM drive.Peer reviewe

Model predictive MRAS estimator for sensorless induction motor drives

Ph. D. ThesisThe project presents a novel model predictive reference adaptive system (MRAS) speed observer for sensorless induction motor drives applications. The proposed observer is based on the finite control set-model predictive control principle. The rotor position is calculated using a search-based optimization algorithm which ensures a minimum speed tuning error signal at each sampling period. This eliminates the need for a proportional integral (PI) controller which is conventionally employed in the adaption mechanism of MRAS observers. Extensive simulation and experimental tests have been carried out to evaluate the performance of the proposed observer. Both the simulation and the experimental results show improved performance of the MRAS scheme in both open and closed-loop sensorless modes of operation at low speeds and with different loading conditions including regeneration. The proposed scheme also improves the system robustness against motor parameter variations and increases the maximum bandwidth of the speed loop controller. However, some of the experimental results show oscillations in the estimated rotor speed, especially at light loading conditions. Furthermore, due to the use of the voltage equation in the reference model, the scheme remains sensitive, to a certain extent, to the variations in the machine parameters. Therefore, to reduce rotor speed oscillations at light loading conditions, an adaptive filter is employed in the speed extraction mechanism, where an adaptation mechanism is proposed to adapt the filter time constant depending on the dynamic state of the system. Furthermore, a voltage compensating method is employed in the reference model of the MP-MRAS observer to address the problems associated with sensitivity to motor parameter variation. The performance of the proposed scheme is evaluated both experimentally and by simulation. Results confirm the effectiveness of the proposed scheme for sensorless speed control of IM drives

Sensorless Commissioning and Control of High Anisotropy Synchronous Motor Drives

L'abstract è presente nell'allegato / the abstract is in the attachmen

Sensorless standstill commissioning of synchronous reluctance machines with automatic tuning

This paper deals with the sensorless selfcommissioning of synchronous reluctance motors at standstill. Previous work demonstrated that the injection of high test voltage pulses can be successfully used to determine the flux linkage maps of the Synchronous Reluctance machine without position transducer and with no need of rotor locking. In this work, the tuning aspects of the above self-commissioning technique are analyzed for making it self-tuning. A method for detecting unwanted rotor movement during the test is introduced and used to assess the test’s end and to maximize the id, iq area of inspection. Furthermore, the paper analyzes a number of theoretical and practical implementation issues, first mathematically and then in experiments. The effects of possible error sources are evaluated, including imprecise estimation of the stator resistance and of the inverter voltage distortion, and iron loss. Experimental results are presented for three Synchronous Reluctance motor prototypes

Advances in Rotating Electric Machines

It is difficult to imagine a modern society without rotating electric machines. Their use has been increasing not only in the traditional fields of application but also in more contemporary fields, including renewable energy conversion systems, electric aircraft, aerospace, electric vehicles, unmanned propulsion systems, robotics, etc. This has contributed to advances in the materials, design methodologies, modeling tools, and manufacturing processes of current electric machines, which are characterized by high compactness, low weight, high power density, high torque density, and high reliability. On the other hand, the growing use of electric machines and drives in more critical applications has pushed forward the research in the area of condition monitoring and fault tolerance, leading to the development of more reliable diagnostic techniques and more fault-tolerant machines. This book presents and disseminates the most recent advances related to the theory, design, modeling, application, control, and condition monitoring of all types of rotating electric machines

Artificial intelligence applied to speed sensorless induction motor drives

During the last two decades there has been considerable development of sensorless vector controlled induction motor drives for high performance industrial applications. Such control strategies reduce the drive's cost, size and maintenance requirements while increasing the system's reliability and robustness. Parameter sensitivity, high computational effort and instability at low and zero speed can be the main shortcomings of sensorless control. Sensorless drives have been successfully applied for medium and high speed operation, but low and zero speed operation is still a critical problem. Much recent research effort is focused on extending the operating region of sensorless drives near zero stator frequency. Several strategies have been proposed for rotor speed estimation in sensorless induction motor drives based on the machine fundamental excitation model. Among these techniques Model Reference Adaptive Systems (MRAS) schemes are the most common strategies employed due to their relative simplicity and low computational effort. Rotor flux-MRAS is the most popular MRAS strategy and significant attempts have been made to improve the performance of this scheme at low speed. Artificial Intelligence (AI) techniques have attracted much attention in the past few years as powerful tools to solve many control problems. Common AI strategies include neural networks, fuzzy logic and genetic algorithms. The mam purpose of this work is to show that AI can be used to improve the sensorless performance of the well-established MRAS observers in the critical low and zero speed region of operation. This thesis proposes various novel methods based on AI combined with MRAS observers. These methods have been implemented via simulation but also on an experimental drive based around a commercial induction machine. Detailed simulations and experimental tests are carried out to investigate the performance of the proposed schemes when compared to the conventional rotor fluxMRAS. Various schemes are implemented and tested in real time using a 7.5 kW induction machine and a dSP ACE DS 1103 controller board. The results presented for these new schemes show the great improvement in the performance of the MRAS observer in both open loop and sensorless modes of operation at low and zero speed.EThOS - Electronic Theses Online ServiceMinistry of Higher Education, Arab Republic of EgyptGBUnited Kingdo

A comparative study of Kalman filtering for sensorless control of a permanent-magnet synchronous motor drive

Author name used in this publication: Borsje, P.Author name used in this publication: Wong, Y. K.Author name used in this publication: Ho, S. L.Refereed conference paper2004-2005 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe

Improved method for the scalar control of induction motor drives

Many control schemes have been proposed for induction motors, which are in themselves highly complex non-linear and sometimes internally unstable systems.One of themost accurate control schemes is encodered rotor flux orientated vector control. The advantages and disadvantages of this control are well known and several variations, or reduced vector schemes, have been proposed. This study introduces an improved encoderless scalar, or approximated vector, control method for induction machines which can be applied to general purpose applications that do not require the most precise control. The proposed method overcomes practical difficulties and is suitable for industrial applications. The slip compensated stator flux linkage oriented scheme proposed in this study does not require flux estimation or a speed sensor, only requiring nameplate data, stator current and stator resistance measurement, which can easily be determined at start-up. Simulation and experimental investigations including field weakening operation and the effect of stator resistance variation demonstrate the improved performance of the new scheme compared to previous open loop V/Hz and stator resistive compensated schemes especially at low rotor speeds