1,720,981 research outputs found
Automatic Parameter Identification of Inverter-Fed Induction Motors at Standstill
No full textAs a step towards the self-commissioning of the next generation of AC drives, the work deals with an automatic procedure for the identification of the inverse-Gamma equivalent circuit of inverter-fed induction motors (IM) at standstill. The algorithm, cut out for the modern microprocessors, combines different test signals with the aim of extracting and mapping the magnetic model non--linearity. As a key feature, the procedure uses the existing inverter as a precise voltage probe, to get the complete parameter set usually required by the advanced control of AC drives.
The theoretical investigations are supported by experimental results, and reported in the paper. A distinguished characteristic of the proposed method among the other existing solutions is the accuracy of the results, confirmed by the comparison with finite-element analysis tools, tailored to the laboratory IM prototypes
Innovative estimation and control techniques in electric drives for mechatronic applications
Full text linkThe research presented in this thesis involves different aspects related to advanced control methodologies and self-commissioning identification algorithms in modern electrical drives. The theoretical study and the validation of the results obtained were performed in the three years of Ph.D. at the Electric Drives Laboratory in the Department of Management and Engineering of the University of Padova, (VI) Italy. The research topics were mainly three, all related to the implementation and development of advanced controls for electric drives, aimed at a more efficient use of the electric machines in the modern mechatronic applications.
The demand of electric drives capable of guarantee high-performance and flexible enough to update in real time the parameters involved in the control algorithm are the motivation of the present research, as well as the meshing or replacement of standard or obsolete control techniques with modern ones, able to fully exploit the new hardware resources. In order to contextualizes and motivate the choice of the present research in the world scenario, a comprehensive bibliographic framework can be found in the introduction of each chapter of the thesis.
The part one of the thesis presents two new control architectures for Permanent Magnet Synchronous Motors, that is a type of electric machine notoriously appreciated by both academia and industry for its flexibility of use and controllability. To this aim, in Chap.2 is proposed a non-linear control algorithm for the automatic search of the Maximum Torque Per Ampere (MTPA) operating condition for Permanent Magnet Synchronous Motors with anisotropic structure, to be integrated in a conventional Field Oriented Control scheme.
The exhaustive convergence and stability analysis performed in order to derive a new and original tuning method of the controller (proven by numerous experimental evidences) is definitely one of the distinguishing features in this research topic.
In parallel to the first topic, for the same type of motor has been investigated and developed (first analytically and then by simulation) a speed and current Direct Predictive Control with Hierarchical decisional structure. Unlike the traditional control techniques, the proposed Direct Predictive Control with modified hierarchical control structure has a faster dynamic and the capability to impose different operating conditions aimed at the energy efficiency optimisation. The on-line execution of the algorithm required for the experimental validation, has become possible thanks to the adoption of a control platform based on FPGA logic (Chap.3). In fact, the processing speed provided by these devices, released from the execution of sequential instructions (typical of the architecture of the microprocessors), ensures an execution time of the algorithm contained in a few us.
The part two of the thesis (i. e. Chap.5) presents an innovative technique of parameter identification for induction motors, capable of estimating the parameters of the equivalent inverse-Gamma electric circuit completely at standstill. As known, the saturations in the parameters of the magnetic circuit of the induction motor and the relative nonlinearities, deteriorate the performance of the standard sensored or sensorless vectorial controls.
The studied self-commissioning procedure addresses and solves many problems related to the estimate of the non-linearity of the parameters, and then it can be considered as an evolution of the classical identification techniques in the literature.
The practical feasibility, doubly validated by numerous experimental tests and by many finite element simulations on three different induction motors, concludes the chapter and proves definitely the method
Maximum-Torque-Per-Ampere Operation of Anisotropic Synchronous Permanent-Magnet Motors Based on Extremum Seeking Control
No full textThis paper presents a theoretical analysis of a Maximum Torque Per Ampere control strategy based on the Extremum Seeking Control working principle, which provides useful insights for the definition of a systematic and quantitative design procedure. The focus is on the convergence properties to the optimal operating point, and a method for evaluating an upper bound of the convergence time is proposed.
The analysis is supported by several experimental tests performed on an Interior Permanent Magnet Synchronous Motor
Hierarchical Real Time Predictive Control of PMSM Drives
No full textThe paper deals with a Direct Predictive Control (DPC) algorithm applied to the speed and current control of a permanent magnet synchronous motor (PMSM) drive. The main contribution is a comprehensive and detailed description of the hierarchical structure, which yields a choice of the control input voltage that combines dynamic performances with the efficiency care. The selection principle is particularly simple and intuitive, and thus it is suitable for direct implementation in standard drives. The paper also gives some practical hints for the implementation. Simulation and experimental results confirm the validity of the design procedure and the potentiality of the proposed technique
Convergence analysis and tuning of ripple correlation based MPPT: A sliding mode approach
No full textThe development of fast MPPT (Maximum Power Point Tracking) algorithms for photovoltaic (PV) systems able to track variable irradiation conditions with high bandwidth is becoming attractive, especially for mobile applications. This paper focuses on the well known ripple correlation technique, proposing an analysis that provides an upper bound to the convergence time in response to solar irradiation steps. The availability an upper bound enables the prediction of the dynamic behaviour of the MPPT, and gives a set of guidelines for a proper tuning of the controller to fit specific requirements. The analysis is based on a simple application of sliding mode theory, and it also includes chattering phenomena and the effects of parasitic reactive elements of the PV module. Matlab simulation and experimental tests are provided on a 35W panel interfaced to a 24V battery through a boost converter. A controllable LEDs illuminator has been used as solar generator, able to provide irradiation step changes with a bandwidth of 1kHz. The results confirm the effectiveness of both the analysis and tuning
A novel approach to torque estimation in IPM synchronous motor drives
No full textEnvironmental-friendly technologies are growing up fast and they are getting more and more attention. In such a scenario, Interior Permanent Magnet (IPM) synchronous motors have all the peculiarities to satisfy the drive efficiency requests. So far, techniques like the Maximum Torque-per-Ampere (MTPA) were a stimulating field of research, because of the great results in term of energy savings. The MTPA locus brings along additional information that is still worth deepening. A proper rearrangement of the torque expression in MTPA condition, obtained by describing the -axis flux linkage by a polynomial approximation, merged with a simple least-square algorithm, returns a fast and accurate on-line estimation of the electromagnetic torque. The effectiveness of the proposed method is proved by a worked out example, based on a IPM drive model fitted with finite-element analysis and experimental measurements, and including motor saturation effects
The influence of the squirrel cage rotor in the estimation of the IM flux linkage at standstill
No full textRecent developments in the field of controls for asynchronous induction motors require a precise knowledge of the parameters of the machine. In particular, the estimation of the stator flux is a matter of highest importance, and many solutions can be found in literature, with different degrees of accuracy and complexity. The present paper deals with an industry-oriented estimation technique, performed at complete standstill, to let the estimation be performed even without disconnecting the motor from the load. In particular, the paper carries out a complete study on the influence of the squirrel cage rotor during the integration usually adopted for the flux linkage determination. A full experimental validation is included, to investigate a problem yet little known. In this regard, two twin machines have been designed and manufactured, with and without rotor cage die casting
FPGA-based Hierarchical finite-states predictive control for PMSM drives
No full textThe aim of the research is the development of a finite-state predictive speed and current control algorithm for a permanent magnet synchronous motor (PMSM). The high computational requirement is one of the main limitations in the calculation and application of the switching states to the inverter, but an alternative control strategy is here proposed. Preliminary simulation and experimental and results obtained with a FPGA-based control board prove the feasibility of the predictive control architecture, both in transient and steady-state conditions
Estimation of the direct-axis inductance in PM synchronous motor drives at standstill
No full textThe call for human mobility reduction pushes research in electrical drives towards the implementation of efficient self-commissioning procedures. As a preliminary and crucial step, an accurate estimation of motor parameters is necessary.
As a part of a process of careful review of existing and often either rough-and-ready or bulky estimation methods, this work copes with the light and precise estimation of the direct flux linkage in permanent magnet motors at standstill. The estimation is based on multi-sinusoidal signal injection, and signal post-processing through Goertzel algorithm, for the sake of very low computational complexity. The procedure considers both iron losses and saturation effects. A set of experimental results show the feasibility of the method, while the comparison with finite element analysis confirms the accuracy of the estimation
Convergence analysis and tuning of a sliding-mode ripple-correlation MPPT
Full text linkThe development of fast Maximum Power Point Tracking (MPPT) algorithms for photovoltaic (PV) systems with high bandwidth and predictable response to irradiation transients is attractive for mobile applications and installations under fast changing weather conditions. This paper proposes the convergence analysis of a sliding-mode version of the MPPT based on ripple correlation control (RCC). The contribution of the paper is a dynamic model, useful to derive a set of design guidelines to tune the sliding-mode RCC-MPPT and achieve a desired dynamic performance under irradiation transients, without a dedicated commissioning phase. The research is based on sliding control theory and it includes both the chattering phenomena analysis and a discussion on the effects of reactive parasitic elements in the PV module. The proposed analysis and design have been validated by Matlab simulations first and then with experimental tests on a 35 W panel with a boost converter charging a 24 V battery. The results support the effectiveness of the proposed modelling procedure and design guidelines, showing good agreement between the model prediction and the experimental transient response
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