Academic literature on the topic 'PERMANENT MAGNET SYNCHRONOUS MMOTOR DRIVE'

Direct drive permanent magnet synchronous generator have the advantages of direct drive, simple structure, high efficiency and so on, in which make it become one of mainstream models within MW wind turbine presently. Making the direct drive permanent magnet wind power generation system as the main research object, based on the principle of the operating characteristics of direct drive permanent magnet synchronous wind generator ( DDPMG ), establish mathematical model of the whole system including wind velocity, wind turbine, direct drive permanent magnet synchronous generator and machine side converter, Appling the method of stator flux orientation to make the study of vector control strategy, to build the simulation model of direct drive permanent magnet synchronous generator system with Matlab and simulate when wind speed changes by step, the results validate the reasonableness of the model and the correctness and feasibility of the control strategy.

Direct drive permanent magnet synchronous generator have the advantages of direct drive, simple structure, high efficiency and so on, in which make it become one of mainstream models within MW wind turbine presently. Making the direct drive permanent magnet wind power generation system as the main research object, based on the principle of the operating characteristics of direct drive permanent magnet synchronous wind generator ( DDPMG ), establish mathematical model of the whole system including wind turbine, direct drive permanent magnet synchronous generator and machine side converter, applying the method of stator flux orientation to make the study of vector control strategy, to build the simulation model of direct drive permanent magnet synchronous generator system with Matlab to simulate the operation of generator when wind speed changes by step, the results validate the reasonableness of the model and the correctness and feasibility of the control strategy.

Permanent magnet synchronous electric machines are increasingly used in various drive technical complexes (oil industry, small generation, aviation industry, etc.). The presented optimization allows you to increase the energy performance of a synchronous machine without increasing the overall dimensions. Permanent magnet synchronous motors have become much more commonly operated in various drive technical complexes. For each drive complex, it is necessary to fulfil the requirements for the developed torque, cooling conditions and strength characteristics. The distribution of materials (topology) in the rotor casing of a synchronous machine (permanent magnets, iron, air, etc) determines the characteristics of permanent magnet synchronous electric machine.

This paper focus on various loading conditions onthe Permanent Magnet Synchronous Motor and its application using field oriented control technique. Constant torqueapplication irrespective of speed isalso presented. This technique helps in lift and belt conveyors handling constant weight of material per unit time, in pumping and compressing and electric locos. Results of simulation shows that proposed system has high acceleration and deceleration rate with vector control,overall quick and dynamic response as well as excellent controlling ability. The vector control is a excellent technology for analysis and design of PMSM drive system. It provides designing and debugging for practical drive system. Modeling and different kinds of Permanent Magnet Synchronous Machines are studied and Simulation is carried out in Matlab and performance is studied at different operating conditions.

A linear permanent magnet synchronous motor drive system is existed in many nonlinear effects such as the external load force, the flux saturation, the cogging force, the column friction and Stribeck force, and the parameters variations. Due to the uncertainty effects, the linear permanent magnet synchronous motor drive system is hard to achieve the good control performance by using linear controller. To raise robustness under occurrence of uncertainty, the integral backstepping control system with hitting function is first proposed for controlling the linear permanent magnet synchronous motor drive system. The used integrator can ameliorate the system’s robustness under the parameters uncertainties and external force disturbances. To reduce vibration of control strength, the integral backstepping control system by means of the revised recurrent fuzzy neural network with mended particle swarm optimization is next proposed to operate the linear permanent magnet synchronous motor drive system to raise robustness of system. Furthermore, four variable learning rates in the weights of the revised recurrent fuzzy neural network are adopted by using mended particle swarm optimization to speed up parameter’s convergence. Finally, comparative performances through some experimental upshots are verified that the integral backstepping control system by means of revised recurrent fuzzy neural network with mended particle swarm optimization has better control performances than those of the proposed methods for the linear permanent magnet synchronous motor drive system.

A direct-drive motor has the merits of low speed, high torque, and elimination of mechanical deceleration mechanisms, and is widely used in various fields. A novel direct-drive permanent magnet synchronous motor is presented herein, in which all coils are wrapped around the stator yoke in the same orientation. The structure of the novel direct-drive permanent magnet synchronous motor with toroidal windings (N-TWDDPMSM) is introduced and its operating principle is analyzed by describing the variation in the armature magnet field versus time. Furthermore, based on the same power grade and mechanical size, several finite-element models of motors with different windings are established using Magnet software to analyze the distribution of magnetic field, back-electromotive force (back-EMF), power-angle characteristics, loss characteristics, etc. Compared with the traditional permanent magnet synchronous motor (T-PMSM), the traditional permanent magnet synchronous motor with toroidal windings (T-TWPMSM), and the N-TWDDPMSM, the N-TWDDPMSM shows advantages of low speed and high torque, and the feasibility and superiority of the N-TWDDPMSM are verified.

To meet the demands of direct-drive petroleum equipment, developed a low-speed and high-torque permanent magnet synchronous motor. By analyzing and identifying the suitable key parameters such as permanent magnet structure parameters, air gap length, type and size of Stator Slot and so on, designed permanent magnet synchronous motor with the torque 10800 Nm, the rated speed 30 r/min and high efficiency and power factor. Obtained the flux density distribution situation and characteristic curves under no-load working condition through simulation and analysis. Manufactured the low-speed and high-torque permanent magnet synchronous motor and applied it to pumping unit. Test results show that this motor has many advantages such as wide range of speed regulation, small torque ripple, smooth operation and other characteristics. The Direct-drive Pumping Unit used this permanent magnet synchronous motor can save 20% energy than the beam pumping unit, so its social and economic benefits are significant.

Permanent magnet synchronous motor is the most drive motor of electric cars, to solve the problem of permanent magnet synchronous motor without position sensor speed control system has speed detection delay, error detection, slow dynamic response etc. The speed of sliding mode observer for permanent magnet synchronous motor used in electric vehicles, analyzes the structure and principle of sliding mode observer, combined with the mathematical model of PMSM, the design of electric vehicle speed sliding mode observer for permanent magnet synchronous motor. The simulation speed of sliding mode observer designed by MATLAB, the simulation results show that the speed of sliding mode observer for permanent magnet synchronous motor in electric vehicle design has the advantages of fast detection speed, small detection error, fast dynamic response etc

Linear motor eliminates the middle part of mechanical drive train, but because of structural characteristics of itself, must to take effective measures to reduce thrust fluctuations, or direct drive will lost its original meaning. In this paper, firstly research on detent force of moving magnet type permanent magnet synchronous linear servo motor and analyze the principle of generate detent force, secondly analyze the cogging force of moving magnet type permanent magnet synchronous linear motor and obtain the expression of cogging force maximum value, finally propose effective method to reduce detent force.

This paper discusses a permanent magnet synchronous motor (PMSM) variable frequency drive (VFD) system developed for an all-terrain Wifi-HaLow connected (802.11ah, 900 MHz) modular electric vehicle that competed in the Mars University Rover Challenge (URC). The quadrature axis flux linkage for each motor was estimated using on-board voltage and current measurements. A synchronous control algorithm tracked the electromagnetic operating parameters, which are highly dependent on variations in motor construction and load conditions. A feed-forward model-driven observer solution calculated flux linkage angles by direct-quadrature-zero transformation of three-phase shunt currents using DSP processors.

Use of permanent magnets made of rare earth materials such as samarium cobalt and neodymium-boron-iron in Permanent Magnet Synchronous Motor (PMSM) drives has resulted in high flux density and improved performance of the drive. Field Oriented Control (FOC) has become one of the most popular speed and torque control techniques for AC motors. In PMSM drive detection/computation of rotor position is crucial for ensuring high performance during FOC. Rotor position is often sensed by incremental encoders or resolvers. The use of positon sensors in motor speed control increases the cost, size, weight and wiring complexity, and reduces the mechanical robustness and reliability of the PMSM drive systems. Sensor-less speed control techniques overcome these drawbacks related to estimation of speed and rotor position. The PMSMs are generally employed in industrial servo applications because of their fast dynamic performance. However, PMSMs suffers from ripples in the torque produced. Torque ripples in PMSM are produced because of cogging, current measurement error, switching of inverter and harmonics in magnetic flux. Torque ripples also leads to fluctuations in speed thus limiting the use of PMSM in several servo applications. Torque ripples could be minimized in applications that demand accurate speed/position tracking. The present work aims to explore use of different modern control techniques to minimize torque ripples in the operation of PMSM drives in comparison to previously reported control techniques. The objectives of the research include – a) modelling, design and development of laboratory prototype of PMSM drive, b) design and implementation of improved artificial neuro fuzzy inference system (ANFIS) based model reference adaptive control (MRAC) observer for sensor-less control of PMSM, v c) minimization of stator current ripples and torque ripples in PMSM drive using advanced predictive current controller (APCC) based on Dead Beat (DB) control theory d) minimization of torque ripples using intelligent hybrid controller (IHC) and e) torque ripple minimization by model predictive control of PMSM using proportional-plus- integral resonant (PI-RES) controller. The strategies to reduce torque ripples, that have been reported in the literature, may be classified into a) approaches based on the design improvement of the motor, b) methods based on control techniques or c) a combination of these two. The most critical aspect in high performance drive is the choice of the control algorithm that minimizes the torque ripples effectively for a given application. In this research work, a laboratory hardware prototype is designed and developed for real time analysis of PMSM drive based on sensor-less field-oriented control. An experimental setup is developed for implementation of FOC on PMSM using dSPACE DS1104 controller and performance of the drive is analysed using different control techniques. An improved ANFIS based MRAC observer is designed and implemented for FOC of PMSM with space vector PWM (SVPWM). In the proposed method adaptive model and adaptive mechanism are replaced by an improved ANFIS controller, which neutralize the effect of parametric variation and results in improved performance of the drive. The required rotor position and speed are estimated using the proposed MRAC observer. Simulation studies using MATLAB/Simulink and comparative analysis of the conventional MRAC based observer with improved ANFIS based MRAC observer show that better dynamic performance of the PMSM drive is achieved using the improved ANFIS based MRAC. vi An advanced predictive controller (APCC) based on deadbeat (DB) control theory is also developed and analysed for reduction of torque ripples in PMSM. The performance of the proposed APCC based on DB control theory are compared with hysteresis based direct current controller (DCC) and duty cycle-based model predictive controller (Duty-MPCC) under different operating condition through simulation studies using MATLAB/Simulink. It is observed that the implementation of proposed APCC results in better dynamic performance with less ripples in torque and stator currents, and lesser THD in stator current as compared to DCC and Duty-MPCC. An intelligent hybrid controller (IHC) has also been developed and implemented for FOC of PMSM to minimize torque ripples for constant torque operation. The proposed IHC is designed by combining a fuzzy logic controller (FLC) with PI controller with a novel switching capability. The intelligent switching decision of the developed IHC is based on overshoots, undershoots and oscillations observed in the system. Simulation studies for the FOC of PMSM using the proposed IHC indicates better dynamic performance with lesser torque ripples and lower THD in stator current in comparison with conventional PI controller. In addition, a proportional-plus-integral resonant (PI-RES) controller is designed and implemented for FOC of PMSM with model predictive controller (MPC) to minimize torque ripples for constant torque operation. The MPC is designed to provide the optimal voltage vector by minimizing the objective function calculated from stator current prediction for k th instant. The PI-RES controller is developed by combining a resonant controller with PI controller. Due to the compensating torque current produced by the resonant controller and reference current from the PI controller, ripples in the speed response are minimized. A PI- RES controller generates the reference pulsating torque current, which counteracts the ripples vii in load torque. The FOC of PMSM with MPC using PI-RES is simulated in MATAB/Simulink and the performance of the drive is compared with MPC using PI controller. The proposed FOC of PMSM with MPC using PI-RES demonstrate better dynamic performance, lower torque ripples and lower THD in stator current in comparison with conventional PI controller based MPC.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2000.
Includes bibliographical references (p. 258-263).
Interior permanent magnet (IPM) synchronous machines are attractive because they can achieve constant-power operation over a wide speed range with limited magnet strength requirements and reduced power electronics cost. These characteristics provide the IPM machine with advantages over alternative machine types in applications such as spindle and traction drives. An important challenge for high-performance IPM machine design is to model the magnetic saturation of the core in a manner that is accurate, flexible, and computationally fast for design optimization. A magnetically-saturable lumped parameter model (LPM) is developed for the optimized design of high-performance IPM synchronous machine drives. Using equivalent magnetic circuit analyses, the dq-frame inductances and magnet flux linkage are calculated for transversely-laminated IPM machines. The lumped parameters are employed to predict machine drive system performance for both rated-torque and constant-power operation. The results of saturable model calculations and finite element analysis (FEA) match very closely for the machine inductances, magnet flux linkage, and converted torque. Further validation is presented by comparing measurements of existing experimental machines to predictions from the saturable lumped parameter model. Agreement of measurements and predictions for the highly nonlinear saturable q-axis inductance is within 5% in the saturated excitation range. The utility of the saturable LPM is then demonstrated by developing a cost-optimized design for an automotive integrated starter/generator (ISG) that is rated at 4 to 6 kW during generating operation. This ISG machine is mounted in a direct-drive mechanical configuration on the engine crankshaft. Agreement between the saturable LPM and FEA calculations for q- and d- axis inductances and PM flux linkage are all within 5% for the entire excitation range. Results of this model have been combined with structural FEA and demagnetization studies to produce a machine design that is predicted to meet all key ISG performance requirements. For this application and the chosen cost model, it is shown that optimizing the combined machine and drive system versus optimizing only the machine reduces the overall cost prediction by 12%.
by Edward Carl Francis Lovelace.
Ph.D.

This doctoral study mainly considers the Wind Energy resource and focuses on the electromagnetic aspects of generators for direct drive solutions in this field. Despite the strong employing by many constructor of geared technology in Wind Turbines Generators, a transmission/gear box reduces both, eciency and reliability: the losses due to the transmission potentially compromise the sustainability of the electromechanical system. A better solution is the multipolar low speed direct drive train. Permanent magnet machines offer compactness and the absence of brushes with respect to traditional machines. Material in the armature can be saved using fractional slot windings. This type of machine exhibits many advantages such as short end windings, high slot fill factor, high efficiency and power density together with electrical redundancy, which allows the modularization of the active part and fault-tolerance capabilities. However, space harmonics of the magneto-motive force (MMF) in fractional slot windings lead to considerable rotor losses. The computation of these losses according to standard procedures (e.g. Steinmetz equation or models for massive body within homogeneous field) is not satisfactory. The MMF harmonics move asynchronously with respect to the rotor, inducing currents in any conductive rotor parts, e.g. the metallic iron yoke which supports the magnetic poles and the rare earth permanent magnets (PMs), acting on their working temperature which is strictly related to the performance of PMs. The reduction of the residual ux density causes a decrease both in the back electromotive force (EMF) and in the electromagnetic torque. The reduction of the magnetic eld increases the risk of an irreversible demagnetization of the PMs. The MMF space harmonic amplitude and frequency depend on the particular combination of number of slots and poles. The amount of such losses increases dramatically with the size of the machine becoming a crucial aspect in the design of a large diameter (v 2 - 3m) multipolar direct drive generators with PMs. A proper selection of the winding of the machine,fixing the number of slot and poles represents an improvement in the sustainability of the electromechanical conversion process: losses are limited and a higher eciency is achieved. If efficiency is better even less active material is wasted. This part of the doctoral study has been accomplished at the Electric Drives Laboratory at the Department of Industrial Engineering of the University of Padova during a partnership with Leitwind A.G.(in Sterzing, Italy), which operates in the Wind Energy Market. The aim is to design a large diameter generator (v 4m), which will be employed in the prototype of a 3 MW wind turbine. The will of Leitwind to implement a method to predict rotor losses in large machines with permanent magnet and fractional slot windings is the key basic point to be solved. The existing LW15C generator for LTW77 (1.5 MW rated power) wind turbine is analyzed by means of analytical relations and finite elements: it represents the starting point of this study. A method to calculate rotor losses due to the high harmonic contents of the fractional slot winding is applied. Such estimated losses are then compared with the results of experimental test benches with "full-scale" prototypes. The same study is then repeated on SFA motor (500 kW rated), employed in ropeways transport in Leitner A.G. plants. Both Leitner and Leitwind belong to the Leitner Technologies Group. Test bench results are finally compared with the values from the analysis. Starting from both the experience on LW15C generator and SFA motor the design of LW30A prototype generator for Leitwind 3MW wind turbine is chosen. Dierent topologies of PM machines with fractional slot winding are then investigated and compared with the switching ux configuration (SFPM), both with rare earths and ferrite PMs. The possibility to integrate a huge magnet quantity in the armature of the SFPM machine and the ux concentration principle can lead to a cost eective solution which must be carefully evaluated without considering the performance of the machine only. The structure of the rotor is robust and simple, like in classical reluctance machines. The robustness against PMs demagnetization is a crucial point to investigate. To extend the scenario of renewable energy, the wave energy resource is brie y overviewed and some topologies for linear direct drive generator in this field are investigated. In order to increase the thrust density the possibility of employing a double-sided structure is analyzed. The employing of ferrite PMs is also considered: despite their low energy with respect to rare earth magnets they have a lower impact on environment and human health. The extraction process of ferrite is similar to the iron one, while rare earths must be separated from radio elements. Main contributions of the thesis To the knowledge of the author, the contributions of this thesis for the upcoming researchers in electrical machines for renewable energy eld are: • The application of straight lined model and of the current sheet method to calculate rotor losses in large direct drive permanent magnet machines. The results of the test bench activity on real machines are then described and compared with the prediction. • Selection of number of slots and poles for fractional winding direct drive large generators. • Comparison of the switching ux machine with other well known machine topologies, including demagnetization behavior and ferrite PMs, more sustainable than rare earth ones. • Investigation on dierent linear modules topologies for wave energy, including double side switching ux topology. Outline of the thesis Chapter 1 provides an overview on renewable energy conversion field and presents the company Leitwind A.G. Chapter 2 describes the analysis and modeling of the LW15C generator for 1.5 MW wind turbine. Then a similar study has been performed for the SFA motor for ropeways applications. Both analytical and finite elements model have been developed/implemented and are compared to the results of experimental test bench activities. The same models are applied to the analysis of the new LW30A generator. Chapter 3 faces the topic of rotor losses in order to model them with the straight lined model and the current sheet method. The rotor losses computation is considered and described. Predicted values are compared with the test bench ones. Chapter 4 establishes a scaling law for rotor losses in fractional slot PM machines. Chapter 5 provides the selection of the number of slots and poles to design the new LW30A generator for 3.0 MW wind turbine. The validity of the Index of Rotor Losses obtained from the straight lined model is investigated and applied. Chapter 6 describes the comparison of fractional winding machine with a small switching ux permanent magnet machine, both with rare earth and ferrite PMs. The demagnetization behavior of the different machine topologies is analyzed. Chapter 7 considers linear drives for Wave energy conversion with different topologies, including the double side switching flux machine
Questo lavoro di dottorato considera principalmente la Risorsa Eolica e si focalizza sulle caratteristiche elettromagnetiche dei generatori a presa diretta per questa applicazione. Malgrado molti Costruttori di turbine eoliche usino congurazioni comprendenti il moltiplicatore di giri, la presenza di quest'organo di trasmissione causa una perdita di ecienza del sistema elettromeccanico che va a comprometterne la sostenibilità. Una soluzione multipolare a bassa velocita di rotazione e presa diretta tra generatore e pale della turbina e quindi adottata. Si sceglie l'utilizzo del magnete permanente grazie alla sua compattezza e all'assenza di spazzole in paragone alle soluzioni di macchina sincrona tradizionale. L'avvolgimento frazionario e adottato per risparmiare materiale nell'avvolgimento di armatura della macchina. Questo tipo di congurazione presenta evidenti vantaggi come la lunghezza ridotta delle testate, il buon fattore di riempimento delle cave, elevati rendimento e fattore di potenza. Essa si presta inoltre a soluzioni circuitalmente ridondanti che consentono una struttura modulare della parte attiva, con la capacita di tollerare i guasti. D'altro canto, le armoniche spaziali della forza magneto motrice (MMF) dovuta all'avvolgimento frazionario causano perdite nel rotore di entita notevole. I metodi tradizionali di calcolo delle perdite (formula di Steinmetz o modelli di corpi solidi in campo magnetico uniforme) non forniscono risultati soddisfacenti per queste perdite. La forza magneto motrice risulta non sincrona con il rotore della macchina, con conseguente indursi di correnti parassite in ogni parte conduttrice del rotore, come nel giogo metallico che sorregge i poli magnetici e nei magneti stessi (terre rare). Le perdite nei magneti ne causano il riscaldamento, con conseguente calo delle prestazioni della macchina. La riduzione del campo dei magneti dovuta all'aumento di temperatura aumenta il rischio di smagnetizzazione irreversibile. L'ampiezza delle armoniche spaziali di forza magneto motrice e la loro frequenza vista dal rotore dipendono dalla particolare combinazione cave{poli dell'avvolgimento scelto. L'entita di queste perdite cresce notevolmente con l'aumentare delle dimensioni della macchina, divenendo un aspetto cruciale nella progettazione di macchine multipolari a presa diretta di grande diametro (. 2m) con magnete permanente. Una scelta adeguata del rapporto cave{poli dell'avvolgimento, signica un notevole miglioramento della sostenibilita del processo di conversione elettromeccanica: le perdite vengono ridotte e il rendimento migliora. Se il rendimento migliora, signica che meno materiale e stato sprecato. Questa parte del lavoro di tesi si e svolta presso il Laboratorio di Azionamenti Elettrici nel Dipartimento di Ingegneria Industriale dell'Universita di Padova nell'ambito di un contratto di ricerca voluto da Leitwind SpA (VIpiteno, Italia). Leitwind e un costruttore di turbine eoliche. Lo scopo e progettare un generatore di grande diametro (v 4m) per il prototipo di turbina eolica da 3 MW. Compresa l'importanza del fenomeno delle perdite rotoriche, la volonta di Leitwind e svilupparne calcolo per scegliere l'avvolgimento della nuova macchina. Il generatore Leitwind esitente, denominato LW15C, per la turbina LTW77 (potenza nominale 1.5 MW) e analizzato sia con modelli analitici che con gli elementi niti. Questo generatore e la base di partenza di questo studio. Viene applicato un metodo per il calcolo delle perdite rotoriche indotte dall'elevato contenuto armonico dell'avvolgimento frazionario. Le perdite cos ottenute sono confrontate con i risultati dell'attivita del banco prova su macchine reali. Con lo stesso approccio si studia e si modella il motore diretto per trazione funiviaria SFA (500 kW di potenza nominale) negli impianti Leitner. Leitner e Leitwind appartengono al Gruppo Leitner Technologies. I risultati del banco prova sono confrontati con i valori calcolati. La progettazione del nuovo generatore LW30A e sviluppata a partire dai modelli creati per il generatore LW15C e il motore diretto SFA. Vengono poi studiate dierenti topologie di macchina a magnete permanente con avvolgimento frazionario per confrontarle con la congurazione switching ux (SFPM). Lo studio prende in considerazione sia magneti di terre rare, che di ferrite. La possibilità di integrare una notevole quantita di magnete nella parte di armatura della macchina SFPM e il principio di concentrazione di usso portano ad una soluzione con un buon rapporto costi prestazioni, che pero deve essere valutata non solo da un punto di vista di prestazioni. La struttura del rotore di questa macchina e semplice e robusta, come per le macchine a riluttanza. Il comportamento della topologia SFPM a smagnetizzazione dei magneti permanenti risulta un punto cruciale da indagare. Per allargare lo studio ad un'altra Fonte Rinnovabile, l'energia da moto ondoso e brevemente descritta e vengono confrontate alcune topologie di generatori lineari per questa applicazione. Uno struttura a doppio statore viene studiata con l'intento di massimizzare la spinta sulla parte mobile. Si considera inoltre l'utilizzo dei magneti in ferrite: malgrado il loro basso prodotto di energia rispetto ai magneti in terre rare, essi risultano meni nocivi per l'ambiente e la salute dell'uomo: il processo di estrazione delle terre rare coinvolge infatti elementi radioattivi, mentre l'estrazione della ferrite e in tutto simile a quella del ferro. Contributi principali della tesi I principali contributi di questo lavoro di tesi alla ricerca futura nell'ambito delle energie rinnovabili si possono cos sintetizzare: • L'applicazione del modello a strati e del metodo dei punti corrente nel calcolo delle perdite rotoriche di macchine elettriche a presa diretta di grande diametro, con magneti permanenti. I risultati dell'attivita sperimentale su banco prova di grosse macchine reali sono confrontati con i valori calcolati. • La scelta del numero di poli e di cave nella progettazione di macchine a presa diretta di grande diametro, con avvolgimento frazionario. • Confronto della macchina switching ux con topologie di macchina note, comprendendo la smagnetizzazione del magnete e l'utilizzo della ferrite, materiale più sostenibile delle terre rare. • Studio di diverse topologie di generatore lineare per generazione da moto ondoso, includendo la topologia switching ux a doppio statore. Struttura della tesi Capitolo 1 : presenta una breve panoramica sull'energia rinnovabile eolica e da moto ondoso e descrive l'azienda Leitwind SpA. Capitolo 2 : descrive la modellazione e l'analisi delle macchine studiate, sia con metodi analitici che con gli elementi niti: sono inclusi i risultati dell'attivita sul banco prova. I modelli, sviluppati sul generatore LW15 e sul motore SFA sono poi applicati al nuovo generatore LW30A. Capitolo 3 : aronta la tematica del calcolo delle perdite rotoriche, sviluppando il modello a strati e il metodo dei punti corrente. Viene descritto il calcolo delle perdite rotoriche. Si aronta la validazione dei metodi di calcolo al banco prova. Capitolo 4 : ricava una legge di scala per le perdite rotoriche per macchine a magnete permanente ad avvolgimento frazionario. Capitolo 5 : presenta la scelta del rapporto cave{poli nel progetto del nuovo generatore LW30A per la turbina da 3.0 MW LTW 101. Viene investigata la possibilità di applicare l'Indice delle Perdite Rotoriche, ricavato dal modello a strati. Capitolo 6 : confronta diverse topologie di macchine ad avvolgimento frazionario con la congurazione switching ux, sia con terre rare che con ferrite. Si aronta il fenomeno della smagnetizzazione sulle diverse topologie di macchina. Capitolo 7 : prende in considerazione topologie di macchina lineare per conversione da moto ondoso. Include la congurazione switchng ux a doppio statore

This research is concerned with the evolution of an advanced drive system for use with permanent magnet synchronous motors. The proposed drive system incorporates state-of-the art control strategies with a switching matrix current loop which is a special case of the sliding mode control loop, implemented using field programmable gate array (FPGA) devices. This significantly increases the bandwidth of the current control loop, in comparison with systems using PI current controllers and therefore improves the dynamic performance of the drive system. The hard-wired FPGA implementation of a current control loop greatly reduces the processing and computational burden imposed on the controller. Most importanUy, in contrast to the OSP technology, independent functions may be implemented without the constraint of a shared arithmetic unit. In this research a novel hard-wired algorithm implementation is proposed for advanced control of brushless permanent magnet synchronous motor (PMSM) servo-drives. The PM servomotor control system has been developed as a set of modular subsystems in the form of algorithms, which can be easily interconnected at the top-level. The novel features of the control system have been made possible by the FPGA implementation with the creation of special algorithms and multiple sampling periods. The application under study is the speed and position control of synchronous motor drives. Initially, a conventional proportional and integral (PI) speed controller was implemented to enable comparison of performance to be made with the forced dynamic control (FOC) law emerging during the final stage of the research programme, which takes advantage of the flexibility offered by digital FPGA implementation. This offers high robustness to uncertainties in the dynamics of the driven load and unknown external load torques and yields a prescribed closed-loop dynamic response to reference inputs. The proposed system not only has the prescribed mutual orthogonality between the magnetic flux and stator current vectors, but also the realisation of a chosen form of speed response transient These FOC strategies have not yet been commercially exploited and it is emphasised that the recent advances in FPGA technology render such control methods highly cost effective. It is therefore anticipated that the outcomes of the research work will provide significant benefits in the development of a new generation of high performance and competitive servo drives.

Fault tolerant machine drives are key enabling technologies for safety critical applications such as electric vehicle traction, and aerospace power generation, actuation and propulsion. High performance in healthy conditions and excellent fault tolerance against various faults are required for a fault tolerant drive, however, these two aspects usually conflict with each other. Thus, this PhD study aims to develop a fault tolerant machine drive which exhibits high performance and good fault tolerance, and can be realised in a simple and cost-effective manner. First, a novel triple redundant 3x3-phase permanent magnet assisted synchronous reluctance machine (PMA SynRM) with segregated windings is proposed. Its performance under healthy conditions and its ability to tolerate various faults with appropriate mitigation measures are investigated and assessed. Based on outcomes of the investigation, a 40kW machine is designed to tolerate all key electrical faults, including the worst single turn short circuit, and is optimised to maximise the efficiency in healthy conditions whilst satisfying the electrical, thermal and mechanical constraints. To analyse and realise a fault tolerant machine drive, fault modelling and fault detection techniques are essential. Thus, a general model is proposed based on the magneto-motive force (MMF) decomposition. The model is capable of predicting the machine behaviour in various operation modes, including the healthy condition, open circuit, short circuit and inter-turn short circuit fault with different number of turns and different coil locations. With the aid of the fault modelling technique, a turn fault detection technique is developed using the 2nd harmonics in the instantaneous reactive and active powers as fault indicators for motoring and generating modes, respectively. By cross-reference of the fault indicators of the three 3-phase sets, the technique can detect the turn fault during transient without false alarm. The optimised machine drive is constructed and the developed fault detection technique together with fault mitigation strategies is implemented in a DSP based controller. The performance of the drive under healthy conditions and its fault tolerant capability are validated by extensive tests. The accuracy of the fault modelling and the effectiveness of the detection technique are also experimentally evaluated. The test results demonstrate that the developed fault tolerant machine drive can be a competitive candidate for safety critical applications.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1997.
Includes bibliographical references (p. 306-310).
by John Ofori-Tenkorang.
Ph.D.

This paper presents a comprehensive evaluation of the performance of an interior permanent magnet (IPM) traction motor drive, and analyses the impact of different modulation techniques. The most widely used modulation methods in traction motor drives are Space vector modulation (SVPWM), over-modulation, and six-step modulation have been implemented. A two-dimensional electromagnetic finite element model of the motor is co-simulated with a dynamic model of a field-oriented control (FOC) circuit. For accurate tuning of the current controllers, extended complex vector synchronous frame current regulators are employed. The DC-link voltage utilization, harmonics in the output waveforms, torque ripple, iron losses, and AC copper losses are calculated and compared with sinusoidal excitation. Overall, it is concluded that the selection of modulation technique is related to the operating condition and motor speed, and a smooth transition between different modulation techniques is essential to achieve a better performance.