Dissertations / Theses on the topic 'Zero speed sensorless control'

This work considers the sensorless control of AC machines for the low and zero speed operation range. Two novel techniques have been developed that use the inherit nature of the inverter PWM to estimate the rotor position of the machine. The inherent back EMF and the saliency of AC machines can be utilized to identify the rotor/flux position. The zero vector current derivative (ZVCD) technique for permanent magnet synchronous machines (PMSM) utilizes both of these effects. No additional test signals are injected into the machine and the difficulty in sensing the machine terminal voltage at low speed is eased. Only three standard current transducers are used in the drive system. For the position/ speed estimator only the machine current derivative during the relatively long (at low speed) zero voltage vectors is used for obtaining the rotor position. Practical results show the operation of the drive at several torque and speed conditions including stand still. A further method has been developed for the sensorless control of induction machines. The high frequency harmonics present in a PWM inverter drive system can be used to detect an equivalent impendence saliency that shows modulation due to rotor/ flux position saliency. The proposed method focuses particularly on the extraction of spatial saliency modulation due to rotor bar slotting effect, which can be used to determine the mechanical rotor position. No additional signal injection is required; the method simply employs some of the inherent PWM carrier harmonics.

Focus of this work is closed-loop speed control of an induction machine based on direct field-oriented control (DFOC) algorithm, using estimates of speed and flux observers which utilize only stator current and voltage. Theoretical bases of the algorithms are explained in detail and their performances are investigated with simulations and experiments. Field Orientated Control is based on projections which transform a threephase time and speed dependent system into a two co-ordinate time invariant system. These projections lead to a structure similar to that of a DC machine control. Transformations are done in synchronous frame alligned to d-axis of rotor flux. So rotor flux position must be known accurately to make these transformations. Degined flux observer, in which voltage model is assisted by current model via a closed-loop to compensate voltage model&rsquo
s disadvantages, estimates the position of the rotor flux. Obtaining adequate torque control via FOC, speed loop is closed using conventional PI regulators. Speed feedback is necessary to complete control loop. Model Reference Adaptive System is studied as a speed estimator. Reactive power scheme is applied to MRAS algorithm to estimate rotor speed. In this study, the direct (rotor) flux oriented control system with flux and speed estimators is described and tested in real-time with the starter kit named TMS320F2812 eZdsp DSK and the Embedded Target for the TI C2000 DSP tool of Matlab

Fast diminishing fossil fuel resources, deterioration in air quality and concerns for environmental protection, continuously promote the interest in the research and development of Alternative Energy Vehicles (AEVs). Traction motor drive is an integral part and common electric propulsion system in all kinds of AEVs. It plays an utmost significant role in the development of electrified transport industry. Application of Induction Motor (IM) drive is not only limited to the domestic and industrial applications but also has an ubiquitous influence in the modern electrified transport sector. IM is characterized by a simple and rugged structure, operational reliability, low maintenance, low cost, ability to operate in a hostile environment and high dynamic performance. However, IM is one of the widely accepted choices by Electric Vehicles (EVs) manufacturer. At present, Variable speed IM drive is almost replacing the traditional DC motor drive in a wide range of applications including EVs where a fast dynamic response is required. It became possible after the technological advancement and development in the field of power switching devices, digital signal processing and recently intelligent control systems have led to great improvements in the dynamic performance of traction drives. Speed Sensorless control strategies offer better system’s reliability and robustness and reduce the drive cost, size and maintenance requirements. Sensorless IM drives have been applied on medium and high speed applications successfully. However, instability at low speed and under different load disturbance conditions are still a critical problem in this research field and has not been robustly achieved. Some application such as traction drives and cranes are required to maintain the desired level of torque down to low speed levels with uncertain load torque disturbance conditions. Speed and torque control is more important particularly in motor-in-wheel traction drive train configuration EVs where vehicle wheel rim is directly connected to the motor shaft to control the speed and torque. The main purpose of this research is to improve the dynamic performance of conventional proportional-integral controller based model reference adaptive system (PI-MRAS) speed observer by using several speed profiles under different load torque disturbance conditions, which is uncertain during the whole vehicle operation apart from the vehicle own load. Since, vehicle has to face different road conditions and aerodynamic effects which continuously change the net load torque effect on the traction drive. This thesis proposes different novel methods based on the fuzzy logic control (FLC) and sliding mode control (SMC) with rotor flux MRAS. Numerous simulations and experimental tests designed with respect to the EV operation are carried out to investigate the speed estimation performance of the proposed schemes and compared with the PI-MRAS speed observer. For simulation and experimental purpose, Matlab-Simulink environment and dSPACE DS-1104 controller board are used respectively. The results presented in this thesis show great performance improvements of the proposed schemes in speed estimation & load disturbance rejection capability and provide a suitable choice of speed sensoless IM drive control for EVs with cost effectiveness.

Thesis (Ph.D.)--Ohio State University, 2005.
Title from first page of PDF file. Document formatted into pages; contains xv, 109 p.; also includes graphics. Includes bibliographical references (p. 106-109). Available online via OhioLINK's ETD Center

Brushless machine topologies have highly favourable qualities for certain applications: no commutator means these machines can be operated at extremely high speeds and because there are no brushes to wear out they are very reliable. It is necessary to know the position of the rotor to operate the machine - this function is performed by the commutator in brushed machine types. For a brushless machine some form of position sensor is normally used to provide the required position information, however, this has drawbacks. Some position sensors can be quite costly and they are often unreliable when operated in hot, electrically noisy environments; decreasing the reliability of an otherwise extremely dependable machine. Several 'sensorless' control schemes have been developed over the years to remove the need for position sensors. This EngD thesis is split into two parts. The first part focuses on a 1,600W, lOO,OOOrpm switched reluctance machine and drive system, used in several products produced by Dyson Ltd. An existing, high-speed, sensorless, control strategy is applied to the machine and the stability of the scheme is analysed. The main challenge with applying a sensorless scheme to this system is the varying nature of the DC link voltage, present due to the low DC link capacitance, which is necessary to reduce costs. A major contribution of this work is the meeting of this challenge. The second part of the thesis examines a 200W, lOO,OOOrpm,battery powered brushless DC machine and a 1,600W, lOO,OOOrpm, mains voltage powered brushless DC machine. A low-speed and high-speed sensorless control system is implemented on the 200W system and the same high-speed sensorless scheme is applied to the 1,600W system. The main difficulty with these machines is that they are single-phase and many existing sensorless methods cannot be applied to them. As with the switched reluctance machine in part one, the 1,600W brushless DC machine has a varying DC link voltage. The main aims were to produce extremely low-cost, reliable sensorless systems that will replace the existing position sensors used on the drives and operate the machines to speeds in excess of 100,000rpm.

For high performance drive applications, the accuracy of speed estimation from a digital shaft encoder is reduced in the low speed range. Drive performance can be further impaired at low speed when low cost low-resolution digital encoders are used. This thesis contributes to the development of a quasi-sensorless solution for AC induction motor drives, where instead of a conventional position sensor and MH" or closed loop observer, an artificial intelligence based 64PPR SKF sensor bearing is proposed. Furthermore, the performance of speed-controlled IM drives is sensitive to rotor time constant mismatch. A newly developed closed loop RMLE-GNA observer is proposed as a new adaption mechanism with a Model Reference Adaptive Scheme for rotor flux estimation and on-fine rotor time constant adaptation. For high performance sensorless speed controlled IM drive applications, the IM is required to operate at low speed in all four-quadrants in a stable manner whilst maintaining constant air-gap flux and torque. Such low speed operation fails with conventional open loop observers and MRAS, and closed loop observers such as EKF suffer from a tuning problem and extensive computing time. Parameter uncertainty is a further factor limiting drive performance. A new joint state estimation and parameter adaptation closed loop Recursive Maximum Likelihood Estimator with an iterative Gauss Newton Raphson Algorithm (RMLE-GNA) is developed for the sensorless speed estimation and on-line parameter adaptation of IM drives. Two case studies are presented: correct and stable convergence of the closed loop observer within two iteration local loops utilising a full order IM model, and correct and stable convergence within a single iteration local loop utilising a simplified full order IM model. In both cases it is shown that the closed loop observer can provide satisfactory and stable convergence for 4-quadrant operation. Of particular interest are the correct convergence, robustness against parameter mismatch and the stability of the sensorless speed controlled IM drive at zero speed and zero stator flux frequency. Thus, a small signal transfer function of the closed loop observer with the sensorless speed vector controlled IM drives is derived. The stability analysis shows the robustness and the convergence of the observer for 4-quadrant operation for high and low speed' and up to the rated load torque. The effect of various machine model parameters on the stability and convergence of the RMLE-GNA-based sensorless drive system is investigated, providing an insight into the inherent dynamic characteristics of the proposed closed loop observer-based sensorless speed-controlled IM drives.

This thesis presents different state estimation techniques for speed sensorlees field oriented control of induction motors. The theoretical basis of each algorithm is explained in detail and its performance is tested with simulations and experiments individually. First, a stochastical nonlinear state estimator, Extended Kalman Filter (EKF) is presented. The motor model designed for EKF application involves rotor speed, dq-axis rotor fluxes and dq-axis stator currents. Thus, using this observer the rotor speed and rotor fluxes are estimated simultaneously. Different from the widely accepted use of EKF, in which it is optimized for either steady-state or transient operations, here using adjustable noise level process algorithm the optimization of EKF has been done for both states
the steady-state and the transient-state of operations. Additionally, the measurement noise immunity of EKF is also investigated. Second, Unscented Kalman Filter (UKF), which is an updated version of EKF, is proposed as a state estimator for speed sensorless field oriented control of induction motors. UKF state update computations, different from EKF, are derivative free and they do not involve costly calculation of Jacobian matrices. Moreover, variance of each state is not assumed Gaussian, therefore a more realistic approach is provided by UKF. In this work, the superiority of UKF is shown in the state estimation of induction motor. Third, Model Reference Adaptive System is studied as a state estimator. Two different methods, back emf scheme and reactive power scheme, are applied to MRAS algorithm to estimate rotor speed. Finally, a flux estimator and an open-loop speed estimator combination is employed to observe stator-rotor fluxes, rotor-flux angle and rotor speed. In flux estimator, voltage model is assisted by current model via a closed-loop to compensate voltage model&rsquo
s disadvantages.

The main focus of the study is the implementation of techniques regarding flux estimation and rotor speed estimation by the use of sensorless closed-loop observers. Within this framework, the information about the mathematical representation of the induction motor, pulse width modulation technique and flux oriented vector control techniques together with speed adaptive flux estimation &ndash
a kind of sensorless closed loop estimation technique- and Kalman filters is given. With the comparison of sensorless closed-loop speed estimation techniques, it has been attempted to identify their superiority and inferiority to each other by the use of simulation models and real-time experiments. In the experiments, the performance of the techniques developed and used in the thesis has been examined under extensively changing speed and load conditions. The real-time experiments have been carried out by the use of TI TMS320F2812 digital signal processor, XILINX XCS2S150E Field Programmable Gate Array (FPGA), control card and the motor drive card Furthermore, Matlab &ldquo
Embedded Target for the TI C2000 DSP&rdquo
and &ldquo
Code Composer Studio&rdquo
software tools have been used. The simulations and experiments conducted in the study have illustrated that it is possible to increase the performance at low speeds at the expense of increased computational burden on the processor. However, in order to control the motor at zero speed, high frequency signal implementation should be used as well as a different electronic hardware.

Permanent magnet motors have a series of characteristics that make them attractive for the use in industrial drives: low maintenance, high dynamics, small size and mass to power ratio. In particular its higher efficiency means that permanent magnet synchronous motors may be used instead of electro-magnetically exited motors (such induction machines or commutator DC motors) in applications where the energy savings compensate the higher initial cost. Nevertheless, the need for a shaft mounted position measurement to perform the orientation of the control of the synchronous machine is of concern, because it increases the total drive cost and reduces reliability. In this work the sensorless vector control of a surface mounted permanent magnet machine is presented. The emphasis is in the control at low and zero speed, including position control, by means of saturation saliency tracking. Two different strategies for rotor position detection used in salient synchronous machines and in induction machines are analysed. These are hf voltage injection in the stationary, stator, reference frame of the machine (α-ß injection) and hf voltage injection on the estimated rotor axis (so called d-axis or pulsating injection). These two methods are optimised for its application to the surface mounted PM machine. The small magnitude of the saliency present difficulties and disturbances are significant. A commissioning based method (SMP) is used for enhanced rotor position estimation by the α-ß rotating injection. The two methods are implemented on a 4 kW experimental rig and the sensorless controlled results are compared and discussed. A hybrid structure combining the saliency tracking method with a flux-observer is also presented and provides sensorless control capability over the whole speed range.

An adaptive wing, a zero mass ux ow control device for low speed airfoil separation control, is investigated both experimentally and computationally at low speeds. The adaptive mechanism in the wings provides variable camber that can be actuated across a range of frequencies and amplitudes. Piezoelectric actuators are housed in a NACA 4415 airfoil with a chord length of :203 m. The entire adaptive wing assembly is then wrapped under a layer of latex membrane to provide a exible and smooth upper surface pro le. Experimental diagnostics include ow visualization, particle image velocimetry, as well as lift and drag measurements. The numerical simulation uses a 2D incompressible CFD code based on a nite-volume structured formulation with a chimera overset grid for the purpose of parallel computing. In the current study, the dimensionless speed range examined is 2:5 104 Re 1:5 105, where particular focus is given to Re 7:5 104, where Re = U` . All experiments and simulations are conducted in the range of attack angles from 0 24 and between reduced frequency values from 0 f+ 1:09, where f+ = f` U1 . Both experimental and computational results show that the region of separation is reduced when the actuation is turned on, thus enhancing aerodynamic e ciency. The maximum coe cient of lift increases by 26% when the reduced frequency, f+, is approximately :2, where the ow control mechanism appears to be most e ective. Phase-locked PIV and CFD vorticity plots reveal that the downward motion of the surface actuation decelerates the boundary ow and increases surface pressure, resulting in the formation of a series of cross-stream vortices that provides uid entrainment towards the suction surface, hence reducing separation.

This work focuses on speed estimation techniques for sensorless closed-loop speed control of an induction machine based on direct field-oriented control technique. Details of theories behind the algorithms are stated and their performances are verified by the help of simulations and experiments. The field-oriented control as the vector control technique is mainly implemented in two ways: indirect field oriented control and direct field oriented control. The field to be oriented may be rotor, stator, or airgap flux-linkage. In the indirect field-oriented control no flux estimation exists. The angular slip velocity estimation based on the measured or estimated rotor speed is required, to compute the synchronous speed of the motor. In the direct field oriented control the synchronous speed is computed with the aid of a flux estimator. Field Oriented Control is based on projections which transform a three phase time and speed dependent system into a two co-ordinate time invariant system. These projections lead to a structure similar to that of a DC machine control. The flux observer used has an adaptive structure which makes use of both the voltage model and the current model of the machine. The rotor speed is estimated via Kalman filter technique which has a recursive state estimation feature. The flux angle estimated by flux observer is processed taking the angular slip velocity into account for speed estimation. For closed-loop speed control of system, torque, flux and speed producing control loops are tuned by the help of PI regulators. The performance of the closed-loop speed control is investigated by simulations and experiments. TMS320F2812 DSP controller card and the Embedded Target for the TI C2000 DSP tool of Matlab are utilized for the real-time experiments.

This thesis deals with the estimation algorithms, reassuming in detail the principles commons techniques and testing them in simulation and by experimentation. The following estimator typologies are discussed: MRAS estimator in the high speed region, estimator based on the high frequency injection signals in the low and zero speed region. As regards the MRAS estimator, after its description, a particular application that exploits this estimation solution is presented. Then, a sensorless control of a Permanent Magnet synchronous motor drive for a hybrid electric catamaran is reported. A Surface mounted Permanent Magnet motor has been chosen and a distinctive sensorless control of this machine is deeply described. Control performance is validated by simulation and experimental results. Start–up mode, reversal of speed and synchronization lost occurrence will be specifically treated. Moreover the estimator sensitivity is studied. The dependence on the stator inductance and the independence of the resistance of the estimation error is demonstrated and verified by means of experimental tests. After that, a high frequency injected voltage for estimating the electrical angular position of the rotor is used for the sensorless control of salient–pole Permanent Magnet (PM) synchronous motor drives. A high frequency speed–dependent ellipse rotating voltage vector is injected to the motor. It generates a high frequency current vector in the estimated synchronous reference frame, that contains information on actual rotor position. This type of estimation technique exploits the anisotropy of the rotor and gives an estimation that is not affected by rotor speed. A recent aspect of the topic intensively investigated is the behaviour of different rotor geometries when subjected to high frequency rotor position estimations and, consequently, the design of sensorless oriented configurations. The reasons of these studies arise from the iron saturation which occurs in the rotor and that modifies and can even cancel rotor saliency and introduces a cross coupling (cross-aturation) between d– and q–axis. This paper experiments the behaviour of two of the principal sensorless oriented rotor configurations (IPM and Inset) and compare the experimental results with those predicted by the finite element simulations carried out during the motor design, in order to validate prediction tools and find out new design hints. In addition, the estimation error dependence on the mutual inductance is demonstrated. Estimation error quantities calculated by means of FEM simulations and measured with experimental tests are compared for both the machines. Main contribution of this thesis consists in introducing a new configuration of SPM motor, in which a turn has been wound around each pole in order to modify the direct axes flux linkage dynamics while preserving the quadrature axis one, thus creating a rotor dynamic anisotropy (ringed–pole rotor). Consequently, the motor can be used in a position sensorless control which exploits the anisotropic rotor features by high frequency injected signals. The model of the machine is described in the paper, and the main equations describing the motor dynamics are reported. Simulations, design hints and experimental results are reported so as to validate the proposed new rotor structure. With this solution, the novel machine can be used in a position sensorless control drive which exploits the anisotropic rotor features by high frequency injected signals. A Ringed-pole motor has been tested with two different estimator: a two states observer and a three states observer. Expected drive performance is validated by simulation and experimental results. Finally the thesis investigates successfully the possibility of extract rotor position information of Interior Permanent Magnet Motors from PWM current harmonic contents. To this aim, a general description of PWM voltage harmonics is at first given. Current harmonics are then derived assuming an anisotropic rotor. It is proved that rotor position information can be derived if single edge PWM is adopted. A speed and position estimation scheme is illustrated and the new rotor position estimation technique is then validated by simulations.
I convenzionali azionamenti elettrici per il controllo dei motori a Magneti Permanenti (PM) richiedo la conoscenza della posizione rotorica per poter applicare le trasformazioni dal sistema di riferimento stazionario a quello rotorico e viceversa. La posizione viene di norma determinata con un trasduttore di posizione che può essere un resolver, sonde ad effetto Hall o encoder. La presenza di questo trasduttore aumenta i costi, la grandezza e la complessità circuitale degli azionamenti e dei motori. Inoltre la loro manutenzione o sostituzione diventa difficoltosa in particolari applicazione, per es. pompe sommerse, macchine per l’eolico, ecc. L’eliminazione di questi trasduttori, quindi, risulta essere un gran vantaggio in termini di costi, affidabilità e riduzione della grandezza fisica del motore o anche dello stesso azionamento. E’ chiaro che questa eliminazione comporta che l’azionamento includa una tecnica alternativa in grado di stimare la posizione e la velocità rotoriche: questi azionamenti vengono definiti azionamenti sensorless. Negli ultimi anni la ricerca ha proposto diverse soluzioni di tipo sensorless che permettono la stima della posizione, diversificando per`o le tecniche per la regione di funzionamento in alta velocità da quelle in bassa velocità o a rotore fermo. Al giorno d’oggi, stimatori basati sulla ricostruzione del vettore di flusso o della fem (stimatori MRAS) vengono utilizzati per il primo caso, mentre nel secondo caso vengono utilizzati stimatori basati sulla iniezione di tensione ad alta frequenza. Mentre nel primo caso la tipologia di stimatore può essere applicata sia ai motori di tipo isotropi che con quelli anisotropi, la seconda tipologia di stimatore può essere applicata solo a motori anisotropi, visto che sfrutta la salienza magnetica per estrarre la posizione elettrica. Questa tesi verte appunto su queste due tipologie di stimatori, riassumendo in dettaglio i principali algoritmi utilizzati oggigiorno e implementandoli sia a livello simulativo che a livello sperimentale. Per una trattazione completa di questo argomento, vengono anche studiate le tre più comuni configurazioni rotoriche (a PM Interni, a PM a montaggio Superficiale ed Inset (incassati)) con una particolare attenzione verso quello che è il comportamento anisotropo o isotropo della macchina stessa e la possibilità di applicare uno o l’altro degli algoritmi sensorless descritti. Entrando in maggior dettaglio, per quanto riguarda lo stimatore MRAS, dopo una sua descrizione, viene presentato in una particolare applicazione che si riferisce ad un catamarano ibrido. Vengono quindi affrontate e discusse le problematiche legate alla strategia di partenza del motore tramite rampa di velocità, dell’aggancio sulla posizione stimata, dell’inversione di marcia. Inoltre viene studiata la sensitività dello stimatore che si dimostra dipendere dall’induttanza di statore e non dalla resistenza. Invece per quanto riguarda lo stimatore basato sull’iniezione di segnali ad alta frequenza è stato per prima cosa descritto sia nel caso con iniezione nel sistema di riferimento statorico sia in quello rotorico. Lo studio è stato effettuato con una formulazione di tipo generale, adattata poi per il tipo di iniezione di segnale effettuata. La trattazione tiene conto anche della induttanza differenziale mutua e questo ha permesso di ricavare un legame tra l’errore di stima la induttanza mutua stessa. Vengono presentati inoltre tre diversi schemi per l’estrazione della posizione elettrica: mediante regolatore PI, osservatore a due stati ed osservatore a tre stati. Dopo di che, lo stimatore con iniezione nel sistema di riferimento rotorico è stato testato sia in simulazione che su banco prova. La bontà dell’algoritmo di stima è stata provata su motori con due diverse configurazioni rotoriche: a PM Interni e di tipo Inset. L’induttanze diretta, in quadratura e mutua sono state studiate in dettaglio con il supporto di simulazioni agli elementi finiti (FEM). Grazie a questo studio è possibile prevedere l’errore di stima che verrà poi confrontato con quello ottenuto dalle prove sperimentali. Come detto in precedenza lo stimatore ad iniezione di segnale può essere utilizzato solo con quei motori che presentano una salienza magnetica. Da questa categoria quindi sono esclusi i motori SPM che, salvo alcune eccezioni come l’Inset, sono isotropi. Si è quindi pensato a come indurre in questi motori un comportamento anisotropo solo alle alte frequenze, cioè alle frequenze del segnale iniettato per la stima. In questa tesi viene presentata questa nuova configurazione rotorica definita "Ringed-pole". Questa consiste nella realizzazione di una gabbia di rotore inserendo degli anelli di rame cortocircuitato attorno a ciascun magnete permanente. La soluzione permette di andare a modificare alle alte frequenze il comportamento magnetico dell'asse diretto, mantenendo invariato quello di quadratura. In questo modo si viene a creare un comportamento anisotropo appunto alle alte frequenze, mantenendo però il comportamento isotropo della macchina per le basse frequenze. Questa caratteristica permette quindi di sfruttare lo stimatore basato sull'iniezione di tensioni alle alte frequenze, per la stima di posizione anche nel caso di motori SPM isotropi. Sono state eseguite simulazioni FEM e prove sperimentali per validare l’idea di base e provare l'effettiva possibilità della stima di posizione. Un secondo contributo riguarda la presentazione di un nuovo stimatore basato sulle armoniche di corrente causate dalla modulazione PWM. L'idea di base consiste nel pensare che la modulazione PWM effettui una intrinseca iniezione di tensione ad alta frequenza, più precisamente alla frequenza di switching. Queste tensioni inducono delle armoniche di corrente alla stessa frequenza che contiene l'informazione sulla posizione elettrica. L'informazione può essere estratta mediante uno schema di stima simile a quello che viene utilizzato nella normale iniezione di tensione. E' stata quindi effettuata una trattazione matematica per ricavare le espressioni delle componenti di tensione e di correnti alla frequenza di switching. Sono state eseguite delle simulazioni preliminari per confermare la correttezza dell’idea di base.

Saab has an analogue solution which is used to drive small motors in aircrafts. The motor is a brushless DC-motor and uses a resolver and hall sensors to control it. As sensorless control is something that has been expanding and attracting more interest over the last decade, Saab is considering the possibility of using a digital sensorless system depending on its performance on the control compared to their analogue system. There is little documentation of performance for a digital sensorless solution compared to an analogue solution. Therefore the question to be answered in this research is: How is the performance of the digital solution compared to the existing analogue solution? It was answered by finding a complete sensorless system on the market and then compare its performance to a digital system with sensors that resembles the analogue solution. Performance wise, InstaSPIN does not perform as well as EPOS2 which represent the sensorless system respective the system with sensors. InstaSPIN needs a startup sequence, can not run at the same low velocities, has a longer rise time, settling time and greater ripple. An examination of the software should be done before using the disadvantages that was found as a reason for not considering a sensorless system. Especially the startup sequence in the software should be examined as it is InstaSPINs greatest weakness compared to EPOS2.
Saab använder idag ett analogt system för att driva små motorer i deras flygfarkoster. Det analoga systemet använder en borstlös DC-motor och en resolver för styrning av motorn. Motorstyrning med system som är oberoende av givare är ett område som vuxit och fått ett ökat intresse det senaste decenniet. Saab överväger möjligheten att använda ett givarlöst digitalt system beroende på dess styrprestanda jämfört med deras analoga system. Eftersom det finns lite dokumentation om prestandan så är frågan som ska besvaras i denna rapport: Hur förhåller sig det givarlösa digitala systemet prestandamässigt jämfört med det existerande analoga systemet? Detta besvarades genom att leta upp ett komplett system på marknaden och sedan jämföra dess prestanda mot ett digitalt system som liknar det analoga systemet.  Prestandamässigt så fungerar InstaSPIN som representerar det givarlösa systemet inte lika effektivt som EPOS2 som representerar systemet som använder givare. Nackdelarna med InstaSPIN är att den behöver en startsekvens, inte kan köra på lika låga hastigheter, har längre stigtid, insvängningstid och större rippel. Man bör undersöka mjukvaran innan nackdelarna används som en anledning till att inte använda ett givarlöst system. Speciellt startsekvensen bör undersökas eftersom det är IntaSPINs största svaghet jämfört mot EPOS2.

In More Electric Aircraft, different power system activities are attributed to electrical means such as the start-up of the main engine. In this context, the study of the sensorless control of the Brushless Synchronous Starter Generator (BSSG) that is used to electrically start the main engine is revealed to be a very interesting issue. For long time, the elimination of the mechanical sensor was highly recommended for reliability, cost, weight, integration issues.Hence, this work aims to transpose the results obtained in the research area to an avionic testbench. It presents an adaptive sensorless technique to use when electrically starting the main engine of the aircraft. This is achieved by elaborating three different methods selected depending on the speed of the machine and based on the :- injection of a high frequency signal- use of the back-emf of the Permanent Magnet Generator (PMG)- use of the extended Kalman Filter EKFIn this work, it is shown that the …first method gives good position estimation results from standstill up to 8% of the rated speed. Then, the back-emfs of the PMG are used to detect the position of the BSSG when the speed exceeds the 8% of the rated speed. Good results are observed with this method at medium and high speed.For redundancy reasons, the EKF was also used in this work. Thus, the estimated position can be delivered via two different estimation algorithms in medium and high speed region.The implementation of the algorithm was achieved on an FPGA board since the latter can ensure a very tiny execution time. The fastness of the treatment ensures quasi-instantaneous position estimation and does not practically introduce any phase lag in the position estimation
Aujourd'hui, l'aviation est en train de vivre des évolutions technologiques concernant surtout l'attribution de différentes fonctionnalités aux équipements électriques et ceci au détriment d'équipements hydrauliques et mécaniques assurant les mêmes fonctionnalités.Dans le cadre de l'avion plus électrique, le démarrage électrique sans capteurs mécaniques de la turbine de l'avion préoccupe les avionneurs de nos jours. Les problèmes introduits par ce capteur ont été identifiés : problèmes de coût et de poids, problèmes de fiabilité et d'intégration.Ce travail présente alors une commande sans capteurs pour la machine synchrone à trois étages à utiliser durant le démarrage électrique de l'avion. Ceci est réalisé avec trois méthodes de détection de la position selon la vitesse de rotation, basées sur :- l'injection d'un signal à haute fréquence- l'utilisation d'un filtre de Kalman étendu FKE- les fém. du PMG (Permanent Magnet Generator) La première méthode donne de bons résultats d'estimation depuis l'arrêt jusqu'à 8% de la vitesse nominale de la machine. Au-delà de cette vitesse, es valeurs des fém. du PMG deviennent assez élevées pour être utilisées dans l'estimation de la position. De bons résultats sont obtenus à moyenne et haute vitesse.Pour des questions de redondance, le FKE est aussi utilisé. Ainsi, la position estimée peut être fournie par l'un des deux algorithmes à moyenne et haute vitesse.L'implémentation de ces algorithmes est réalisée via une carte FPGA étant donné que celui-ci garantit un temps d'exécution. La rapidité de traitement garantit une estimation de la position quasi-instantanée et donc n'introduit pratiquement pas des retards dans l'estimation

The invention of the Rotor Field Oriented Control (RFOC) has made the induction machine (IM) dominate the high performance drives market. Fifteen years later, the Direct Torque Control (DTC) strategy has been introduced to give fast torque and flux control with reduced software and hardware requirements. However, the use of flux, speed, current and three-phase stator voltage sensors to monitor the drive states increase the drive cost and reduce the overall system reliability. The number of sensors can be minimised using estimation. However, estimation at low stator frequency operation suffers from pure integration, stability problems, observablity problems, parameter detuning and inverter non-linearity. Thus, it has been suggested to develop and implement stable sensorless RFOC and DTC drives with stator and rotor resistance estimators that can work at low stator frequency with minimal number of sensors. Thus, two types of model reference adaptive system (MRAS) estimators that do not include pure integration have been adopted. A novel design procedure based on linear control theory has been stated to design stable speed, stator resistance and rotor resistance estimators in various operating modes for individual and simultaneous use. The observablity problem at zero stator frequency operation has been eliminated using high frequency injection. The inverter non-linearity has been modeled and thus the model has been used to compensate the inverter voltage losses. The designed estimators have been employed to realise and implement stable sensorless RFOC and DTC IM drives that work at low stator frequency. Furthermore, the classic DTC with fixed switching frequency suffers from torque ripples, flux ripples, torque control offset and flux collapse at low speed and light load. A novel torque ripple minimisation (TRM) DTC scheme has been proposed to predictively eliminate the torque ripple and reduce the flux ripple and also eliminate the torque offset and the flux collapse. In addition, a novel Space Vector Modulation (SVM) DTC has been proposed as an alternative to the TRM DTC scheme and has shown better performance and less computational time. To achieve successful development of sensorless RFOC and DTC drives which can work at low speeds, well-designed stable estimators are the key factor. This research work has given important contribution towards clear vision to analyse and design stable parameter estimators for RFOC and DTC IM drive. It follows, stable speed and stator and rotor resistance MRAS based on back-EMF estimators have been designed for individual and simultaneous use, following the proposed design procedure. These estimators have been employed to implement a stable sensorless RFOC IM drive for low speed operation that insensitive to parameters variation. The performance of the drive has been investigated extensively using simulations and experimental work. In addition, stable speed and stator and rotor resistance MRAS based on current estimation estimators have been designed for individual and simultaneous use. These estimators have been also used to realise a stable sensorless RFOC IM drive for low speed operation. Simulations and experimental work have been carried out to also investigate the performance of the drive. These stable estimators have been also employed to develop two stable sensorless SVM and TRM DTC IM drives for low speed operation and insensitive to stator resistance. The performance of the drives has been investigated for low speed operation using simulations and experimental work. They have shown excellent performance.

ABSTRACT SENSORLESS DIRECT FIELD ORIENTED CONTROL OF INDUCTION MACHINE BY FLUX AND SPEED ESTIMATORS USING MODEL REFERENCE ADAPTIVE SYSTEM This work focuses on an observer design which will estimate flux-linkage and speed for induction motors in its entire speed control range. The theoretical base of the algorithm is explained in detail and its both open-loop, and closed-loop performance is tested with experiments, measuring only stator current and voltage. Theoretically, the field-oriented control for the induction motor drive can be mainly categorized into two types
indirect and direct field oriented. The field to be oriented may be rotor, stator, or airgap flux-linkage. In the indirect field-oriented control, the slip estimation based on the measured or estimated rotor speed is required in order to compute the synchronous speed. There is no need for the flux estimation in such a system. For the direct field oriented case the synchronous speed is computed with the aid of a flux estimator. In DFO, the synchronous speed is iv computed from the ratio of dq-axes fluxes. With the combination of a flux estimator and an open-loop speed estimator one can observe stator-rotor fluxes, rotor-flux angle and rotor speed. In this study, the direct (rotor) flux oriented control system with flux and-open-loop speed estimators is described and tested in real-time with the Evaluation Module named TMS320LF21407 and the Embedded Target software named Vissim from Visual Solutions Company.

博士
國立臺灣科技大學
電機工程系
98
This research proposes control methods to achieve the goal of very low speed and zero stator frequency operation for a speed sensorless vector-controlled induction motor drive. The speed estimation is first formulated using a full-order rotor flux observer and an adaptive speed estimator. It is further improved by a phase shift technique and by an injection of a low-frequency signal. Then a model reduction technique is proposed, which reduces the computational complexity of the control algorithms and is still applicable to zero stator frequency operation. Furthermore, this research proposes a new MRAS approach due to solve the problem of motor parameter sensitivity, the estimators for rotor speed, stator resistance, and rotor resistance can be simultaneously set up, which lead to a multi-input multi-output cross-coupled dynamic system. To achieve simultaneous estimation of the three estimators, a stability criterion is established and a systematic design procedure is proposed. Experimental results are divided into two phases, the first one is presented to show the validity of the proposed methods in such driving modes as zero stator frequency, reversible speed, and zero rotor speed control. Finally, the simultaneous estimation system of three estimators is further verified by experiments, which show that the proposed control strategy stabilizes the drive in both motoring and regenerating modes.

博士
國立臺灣大學
電機工程學系
86
This dissertation presensts a new sensorless speed estimation method for induction motor, which replaces the feedback signal of conventional speed sensors. Using the proposed method, closed-loop speed control is accomplished without any speed measurement. The proposed method is based on an adaptive flux observer, in which a second-order Kalman filter is employed to modify the esitmated rotor flux using the actually measured stator currents. The modified rotor flux estimate is substituted into the speed estimation equation derived in the adaptive observer to improve the speed estimation results. In comparison with the reduced-order Kalman filter method, the proposed method reduces the computation complexity. Moreover, the proposed method improves the accuracy of speed estimation compared with the conventional adaptive observer, while maintaining the computational load moderate. In the experimental implementation, vector control and direct torque control are investigated to verify the effectiveness of the proposed speed and flux observer. With the proposed method, speed sensorless control of induction motor is achieved. Experimental results shwo that the proposed speed estimation scheme improves the accuracy of speed estimation compared with the conventional adaptive observer. The proposed method is proven to be an effective speed sensorless control strategy of induction motor with moderate computational load.

碩士
國立高雄應用科技大學
電機工程系博碩士班
101
The thesis proposes the design of speed control by using a simple microprocessor. Our design does not have either a speed sensor or the relevant circuit, which is often used to detect the speed of motors. The microprocessor merely measures the voltages of the motor terminals as well as the motor current and is then able to estimate the speed of the permanent magnet DC brushed motor based on the mathematical model of motors. This greatly reduces the cost and space required. Microchip PIC16F1827 is used as the central processing unit. The main control approach is based on a bang-bang control algorithm. It adjusts the duty cycle of PWM (Pulse Width Modulation) in order to maintain and stabilize the required speed of treadmills. The system also keeps monitoring on exceptions due to improper usage or any accidents for safety. At the end, the thesis implements a PIC-based sensorless speed regulation control unit and connects it to a treadmill and justify its feasibility.

碩士
淡江大學
機械工程學系
88
The objective of this thesis is to develop a sensorless speed estimator for induction motor drives. From the state equations of the induction motor, we derive the estimation algorithm of which inputs include stator currents and voltages, and rotor flux. In order to reduce the hardware burden, only currents of two phases are measured by using hardware sensors, while the voltages and rotor flux are determined by using software estimates. For the voltage estimation, we utilize the PWM switching states that are created by a DSPC240 controller. On the other hand, a voltage model observer is used for the rotor-flux observation. Because of the insignificant variation of parameters in high frequencies, the voltage model is usually applied in high-speed operation. For the situation of low-speed operation, we propose a compensation method for the flux command. Therefore the zero-crossover speed will be quite smoothly. There are many advantages to measure currents, voltages, and rotor flues by using estimates. We can filter out the external noise by the software estimates and increase the robustness of the system. Furthermore, the omission of the hardware sensor will simplify the system mechanism and reduce the cost price. With the estimated rotor speed, we can form a closed-loop velocity control system that will provide larger torque outputs in low-speed operation than those by a pure V/F control. We develop the servo-controller by using TI DSPC240 to implement the sensorless speed control algorithm. The control command is sent to a power drive made by ITRI, which would regular the motion of an 1-HP induction motor. Experimental results show that the proposed estimates can efficaciously provide the rotor speed in various operational situations.

碩士
國立高雄應用科技大學
電機工程系博碩士班
101
The thesis mainly focuses on the implementation of a sensorless motor control design for a treadmill. In order to control the speed of the treadmill in a stable fashion, the design estimates how fast the PMDC motor turns by combining the measurements of the current flowing through the motor and motor terminal voltages. To estimate the best membership function of the speed calculation equation and accurately approximate the speed, the estimator is based on fuzzy modeling and the least squares analysis. The controller also implements a fuzzy PID loop to control the speed of the PMDC brushed motor to effectively regulate the speed of the treadmill. At the end, the results of design and experiments are realized by programming a PSOC micro-controller to prove its validity.

碩士
國立臺灣科技大學
電機工程系
98
This thesis presents the control of speed sensorless permanent-magnet synchronous generators. In this system a novel ac-dc-ac power converters is proposed to convert three-phase electrical power generated by wind with varying-voltage and varying-frequency to that of single-phase with constant-voltage and constant-frequency. In ac-dc power converter, the mathematical model of three-phase rectifier built under rotating-frame and synchronous frame phase-locked loop is used to estimate rotor position. This requires no rotor position detector and thus increases the reliability of the system. Wind power generation system with maximum power tracking control perturbation and observation method is proposed to observe the changes in generator output power and make adjustments to current orders for the next duty cycle. A single-phase dc-ac power converter using unipolar switching method with low switching loss is designed to reduce the output current harmonics and increase conversion efficiency. As mentioned above, the realized system can be operated in parallel with the power grid by voltage and current control models. The high-performance and low-cost digital signal processor DSP,TMS320F2808 is used to control the power converter. When generator runs at 90rpm, a prototype of 465W power conversion system is developed for grid-connection. The single-phase grid-connected operation yields the output voltage of 220V, 60Hz. Besides, the experimental data show that the efficiency of the whole system reaches 86.11% with current harmonic distortion of 13.77%. This generator can maintain a stable output voltage to provide a single-phase DC-AC power converter and grid-connected operation when speed is running between 10m/s to 12m/s. Experimental results are shown to verify the feasibility of the proposed scheme.

碩士
國立臺灣科技大學
機械工程系
106
AC motor have become popular in the industries globally due to the booming of vector control. Among them, induction motors(IM) have a wide range of applications because of its sturdiness and durability. To reduce the expenses and to open more possibilities on its application speed-sensorless control is preferred. However, in applying speed-sensorless control efficiently an observer is needed. The noise immunity and real time estimation ability of Extended Kalman filter(EKF)-based observer lead to a popular application in field of speed-sensorless control. This thesis utilize EKF based estimator and FOC as the controller in order to completed the speed-sensorless control. The experimental results show that the FOC has good control performance, and can maintain the zero steady error and the RMSE within 6 rpm under the designed operating conditions of constant speed variable loading and variable speed constant loading. The convergence efficiency of the estimator is acceptable. The convergence time of speed and load in 1.5 seconds, the Maximum of the steady state error is also less than 0.1%. The control performance of EKF-based speed-sensorless control works well. The Maximum of steady state error of the speed is less than 1.5% and the RMSE within 30 rpm. Due to the estimator delay and the maximum overshoot of the controller, the estimation of the rotational speed change and the control performance are not so well.

碩士
國立交通大學
電機與控制工程系所
95
In this thesis, the fuzzy logic controller (FLC) for sensorless brushless dc (BLDC) motor was proposed to synchronize the rotors with the stator windings commutation sequence to obtain the optimum efficiency of motor. There are two modules proposed in the speed control of BLDC motor, i.e. command and regulating modules. Command module is to find and issue commutation period and PWM duty cycle to the BLDC motor for desired speed. The regulating module is designed as a FLC and is used to regulate the speed of BLDC motor subject to disturbances, such as loading effect. Two resistances are adopted to detect the back-EMF signal on the unexcited phase instead of using the expensive Hall sensors. The regulating module can accurately and quickly regulate the PWM duty cycle by fuzzy reasoning which makes the BLDC motor rotate smoothly at desired rotational speed even if there is an external disturbance. In order to reduce the computational load of real-time FLC for the microcontroller C8051F330, we can perform the FLC computation off-line to cover nearly all cases. These data will be recorded and organized as a Look-Up Table (LUT). The regulating module is designed by FLC yield the better results than that without regulating module, and the regulating module via P controller.

博士
國立臺灣大學
電機工程學系研究所
86
This dissertation presents the automatic parameter measurement and adaptive reduced-order flux observer for sensorless field-oriented controller(FOC) of a n inverter-driven induction motor(IM) to effectively improve the controller pe rformance.In order to improve the preset parameters of the sensorless FOC, a novel approach of automatic IM parameter measurement is presented. Before sta rt-up, the inverter drive automatically performs the dc test, the no-load test (including iron loss under various frequencies), and the locked-rotor test for the driven IM. The only measured values are input current signals. No addit ional hardware is required in this approach. Finally, the test data are then computed to get the IM parameters and the field current commands under various frequencies for FOC.In order to improve the performance of sensorless FOC, a n adaptive reduced-order flux observer is presented. In comparison with the a daptive full-order flux observer, the proposed method consumes less computatio nal time and illustrates better speed performance. The proportional gain of t he proposed observer can be utilized for wide speed range control. Simulatio n and experimental results both show the effectiveness, correctness and accura cy of the proposed methods. An integrated study of the proposed methods has b een tested on a 3-hp inverter-driven IM system.

碩士
國立臺北科技大學
電機工程系電力電子產業碩士專班
106
The sensorless control strategies for PMSM drives mainly include high frequency (HF) injection and position observer based on motor model. The information of rotor position depends on the inductance difference between q axis and d axis for low speed. Due to the saliency ratio of SPM is relatively small, it’s hard to estimate the rotor position by the characteristics of inductance. A sensorless speed control is proposed in this thesis. The phenomenon of current rise caused by the saturation of inductance, when the rotor magnet is approaching to the stator coil, is utilized as the detection basis at standstill. To identify the state of the six current vectors and their magnitudes under 180 degree conduction, thereby the rotor position is estimated at standstill. Then, the 120 degree commutation is applied for low speed operation. The magnetic saturation occurs when the rotor magnet is close to the excitation stator windings, therefore the open phase winding will yields an electromotive force due to the change of magnetic flux. The current commutation of six-switches is according to detect the open phase voltage within six switch states. Finally, a DSP-based(TMS320F28035) motor drive is built to verify the effectiveness of the proposed strategy with a 350W/6000rpm SPM.

碩士
國立臺灣科技大學
電機工程系
99
This thesis aims to implement the sensorless speed control system for brushless direct current (BLDC) motor with the Field Programmable Gate Array (FPGA) chip. It could determine the position of rotor according to the information of back electro motive force (back-EMF) without Hall sensor. This system use the analog to digital converter (ADC) to detect the back-EMF zero crossing points, then commute the motor. But the estimation for zero crossing points would be easily interfered by noise signals.The interference with noise could be reduced with some suitable decision rules.So this system could detect the zero crossing points correctly. And let the motor spins smoothly.

碩士
國立臺灣大學
電機工程學研究所
91
In this thesis, a DSP speed sensorless vector control system of three-phase induction motor is the principal implementation. The author adopts the direct vector control for an induction motor drive system. The rotor flux is estimated by a modified voltage model observer. A close loop control system is constructed by a speed observer which estimates the rotor speed. In the case of a PWM modulation method, the space vector modulation is well utilized in the speed sensorless vector control system and makes the lower harmonic losses with respect to SPWM. To evaluate the performance of the control system, simulations were carried out using the MATLAB/SIMULINK software package in addition. The full system is implemented with the TI TMS320F2407A EVM board, peripheral circuits and assembly language programming. The proposal of this thesis which links the hardware, simulation results and the experiment results were presented.

碩士
南台科技大學
電機工程系
93
This main research of this thesis is to develop an intelligent sensorless speed controller for permanent magnet synchronous motor (PMSM) using the TI-TMS320F2812 DSP. In sensorless technique, a sliding mode observer and a low-pass filter is utilized to estimates the back-EMF of the PMSM, then the magnetic angle and rotor speed of the motor is obtained using the estimated back-EMF value. These estimated values are feedback for vector control in the current loop and for speed control in the speed loop. To increase the performance of the speed controller, an adaptive fuzzy controller consisted by a fuzzy controller, a reference model and adjustable mechanism is applied and the rules of the fuzzy controller can be updated in real time by adjustable mechanism. Combined the sensorless technique and adaptive control technique into the speed controller of the PMSM drives, and the performance can be improved, the cost can be reduced and the reliability can be increased. The DSP chip used in the thesis has the complete motor peripheral which includes 12 channels of PWM output, 2 set of QEP input, 12 channels 12-bit A/D converter and 56 bits GPIO, and, therefore it is very suitable for develop a fully digital AC motor drives which need to perform the functions of the intelligent controller, coordinate transformation, SVPWM output, QEP detection, vector control and magnetic angle estimating method. At last, an experimental system, based on TI TMS320F2812 DSK board, is set up and some experimental results are proven the correctness and validity of the proposed control algorithm.

碩士
國立暨南國際大學
電機工程學系
96
At present, lots of permanent magnet synchronous motors (PMSM) are commonly utilized in modern industries. Synchronous AC motors could be simply classified as PMSM and brushless DC motors according to sinusoidal or trapezoidal flux distribution, respectively. The advantages of a PMSM include superior high power density, large torque to inertia ratio and high efficiency, so it has been widely employed for many industrial drives. The vector control scheme can decouple the system dynamics of PMSM on various reference frames and it can apply current feedback control to track the reference rotor velocity. First of all, the nonlinear control design of PMSM systems is considered, and the proposed methodology incorporates the sliding mode algorithm to track the rotor speed. In addition, the nonlinear speed tracking controller is developed for a PMSM system based on adaptive sliding mode approach to cope with system uncertainties. So far, these nonlinear control designs are attained with the assumption of measurable rotor speed. In general, the PMSM speed tracking design requires the measurement of angular velocity to achieve control goals, but most PMSM systems do not have speed measurement devices. Therefore, the nonlinear backstepping controller with observer, which is employed to estimate the unmeasurable angular velocity, is proposed to achieve speed tracking control. Furthermore, if the system cannot have velocity observer and system parameters are unknown, the sensorless speed tracking control design without observer is developed for a PMSM system based on adaptive backstepping design scheme. As a result, the excellent performance of the nonlinear controller design scheme can be illustrated through comparative simulations applied to a PMSM.

碩士
國立中山大學
電機工程研究所
84
This thesis will provide a sensorless like position measurement scheme applied onto a transverse flux linear switched reluctance machine system. A simple and compact closed-loop scheme will be developed to handle the system position and speed estimation tasks. It is understood that except those operating regions which are designed for machine starting and breaking, the entire linear machine system will be generally operated in a smooth speed condition. Consequently, with the installation of minimized number of position sensors and the implementation of some sophisticated estimation algorithms, the machine system behavior can then be identified. From the system verification results, it is believed that the objective of developing an economical and fast position estimation scheme, suitable for long distance transportation system using linear machine, has been achieved.

碩士
國立中正大學
機械工程系研究所
106
This thesis mainly builds up the permanent magnet synchronous motor sensorless vector control technology. The permanent magnet synchronous motor can be divided into two types: surface-mounted and interior-mounted. Because of the saliency of motor, we have to choose different sensorless control technology for different types of motors. In this thesis, surface-mounted permanent magnet synchronous motor is used for DSP controlled target. In low speed command situation, we utilize low-frequency signal injection (LFSI) method for surface-mounted permanent magnet synchronous motor to perform sensorless control. Because of the back EMF of the motor, this method can only be used in low speed command situation. In high speed command situation, we use model reference adaptive control system (MRAS), which is self-adaptive sensorless control technology and it performs well in high speed command situation. For the stability when changing sensorless control technology for different speed commands, we adjust the control parameters to improve the dynamic response. We use MATLAB Simulink to identify the result, and use TMS320F28379 digital signal processor (DSP) motion control card to carry out the sensorless motor control.

Hybrid Electric Vehicles (HEVs) are exciting new additions to the car markets since they combine the best features of conventional and electric cars to improve environmental performance and reduce fuel consumption. HEVs get their driving power from both an internal combustion engine and an electric motor. Many researches have demonstrated the induction motor is one of the right electric motor candidates for the most HEVs due to its low cost, robustness and low maintenance. The objective of this research work is to develop a new speed-sensorless control method for induction motors to optimize torque response and improve robustness in order to meet the requirement of HEV applications. The proposed new control method is based on Sliding-Mode Control (SMC) combined with Space Vector Modulation (SVM) technique. The SMC contributes to the robustness of induction motor drives, and the SVM improves the torque, flux, and current steady-state performance by reducing the ripple. The Lyapunov direct method is used to ensure the reaching and sustaining of sliding-mode and stability of the control system. A sliding-mode observer is proposed to estimate the rotor flux and speed. Computer simulation results show that the proposed control scheme owns very good dynamic characteristics, high accuracy in torque tracking to various reference signals and strong robustness to external load disturbances

碩士
國立交通大學
電機與控制工程系所
93
Owing to the high power density and high efficiency, BLDC motors have been used in various applications, such as the computer peripheral machines, household appliances, industrial machines and public transit systems. In general, the information of the motor’s position is required in controlling the BLDC motor. However, some drawbacks exist. For instance, the motor size and cost will be raised and the position censor will be influenced by the motor temperature inside. Therefore, recent investigators have paid more and more attention to sensorless MLDC motors, which can be operated without any position sensors. A 3-phase BLDC axial-flux wheel motor is used in this thesis. It is a low speed and high torque direct-drive motor. The goal is to design the sliding mode estimator for sensorless BLDC motor in speed control. The motor’s model is established by Matlab®�{Simulink® at the beginning. Next, the sliding mode estimator is designed and added upon the speed feedback control. Finally, the hardware experiment is set up to verify the method proposed in this thesis. The whole design process will be proposed in detail in this thesis.

碩士
崑山科技大學
電機工程研究所
97
This thesis proposes the fuzzy controller to the speed control of sensorless brushless DC Motor (BLDC) based on digital signal controller dsPIC30F4011. The BLDC mainly uses inverter to substitute for carbon brush and commutator. Under the incentives of both energy and environmental protection, BLDC will substitute for DC motor and will become the drive component of high-efficiently environment-friendly product. In general, the BLDC can be divided into sensor drive and sensorless drive techniques. The sensor drive technique uses Hall sensors to detect rotor position, which can be successfully started up whenever motor is static or operated at low speed condition. But due to the installation of Hall sensors, the motor size is large and the cost is increased. The sensorless drive technique employs back electromotive force (BEMF) signals to detect rotor position, which can improve the disadvantages of sensor drive technique. To carry out the close-loop speed control, this thesis applies fuzzy theory to design a controller which can accommodate the response of load variation. Fuzzy controller can make a good control whenever the system is nonlinear or its mathematical model is unknown. Therefore, the fuzzy controller is widely used in the industrial circles. To verify the feasibility of the proposed method, this thesis employs three-phase brushless DC motor (1.5Hp) to fulfill the experiments. The proposed method utilizes start-up experiment to validate the feasibility of BEMF method. Then the fuzzy controller is employed to verify the control performance under different speed commands with load variation.