Differential-Algebraic Approach to Speed and Parameter Estimation of the Induction Motor

This thesis considers a differential-algebraic approach to estimating the speed and rotor time constant of an induction motor using only the measured terminal voltages and currents. It is shown that the induction motor speed satisfies both a second-order and a third-order polynomial equation whose coefficients depend the stator voltages, stator currents, and their derivatives. Further, it is shown that as long as the stator electrical frequency is nonzero, the speed is uniquely determined by these polynomials. The speed so determined is then used to stabilize a dynamic (Luenberger type) observer to obtain a smoothed speed estimate. With full knowledge of the machine parameters and filtering of the sensor noise, simulations and experiments indicate that this estimator has the potential to provide low speed (including zero speed) control of an induction motor under full load. A differential-algebraic approach is also used to obtain an estimate of the rotor time constant of an induction motor, again using only the measured stator voltages and currents. Experimental results are presented to demonstrate the practical use of the identification method

Belt Driven Alternator and Starter with a Series Magnetized Synchronous Machine Drive

Electric Hybrid Vehicles, EHV, are under development to provide lower fuel consumption levels and minimize the environmental pollution compared to pure Internal Combustion Engine, ICE, driven vehicles. The EHV is more complex and thus carry many more extra parts than the pure ICE based vehicle. Competing against the pure ICE vehicle in the sense of nonexpensive mass production is hard. This thesis is a result of a research project with the goal to develop a complete Belt driven Alternator and Starter, BAS, system for a Stop&Go functionality as a cost-effective hybrid vehicle solution. BAS is based on a Series Magnetized Synchronous Machine, SMSM, which as an adjustable-speed drive system comprises power electronics but excludes permanent magnets. BAS is a rather old concept. It merges two functions, an electric starting motor and an generator, into one single electric machine. It thereby makes the total system lighter and smaller. Furthermore, it facilitates technology leaps on the road towards mass production of electric hybrid vehicles. The developed BAS system is suitable for a midrange passenger vehicle. The Stop&Go functionality provides an ICE turn-off at each vehicle stop. The SMSM is, in addition to generating electricity and starting the ICE, intended to support the ICE with an additional torque when it is assumed beneficial in the sense of reaching low fuel consumption. Topics in the field of power electronics and control of the SMSM that are covered in this thesis are: • Simulations on vehicle basis are performed for optimizing the rated power of the electric machine and its power electronics in the sense of low fuel consumption. • The Series Magnetized Synchronous Machine, SMSM, and the theory lying behind it are presented. The SMSM is carefully investigated both magnetically and electrically. • A simulation model for the SMSM is derived based on the theoretical model that describes the SMSM. • Based on the theoretical model of the SMSM, dedicated current controllers are derived. Other types, as standard PI controllers and a so-called field voltage vector feed forward controller are investigated and simulated for control of the SMSM. • The SMSM is tested in laboratory environment for confirming the behaviour of the derived model of the adjustable-speed drive system including its power electronics

Re-adhesion control for railway traction systems

Slip is a harmful phenomenon in railway. It causes the wear of wheel rail contact surface and mechanical stress of the traction system. Moreover, it may affect the stability of the whole system. The study is concerned with the development of a novel slip detection and re-adhesion control using practical position encoder. In detail, this thesis presents a powered wheelset system driven by an induction motor associated with vector control unit The ~heelset models developed from the study include a comprehensive model which involves longitudinal, lateral and yaw dynamics, a distributed parameter model and a. lumped parameter model with simplified longitudinal dynamics. The dynamics of a wheelset is ~tudied and compared in normal conditions and slip conditions. Simulation results show typical torsional vibration occurs when slip happens. Two possible approaches of slip detection based on the vibration phenomenon are discussed. The first one monitors the torsional torque to detect the slip based on the direct torsional torque measurement In the second approach, a Kalman filter based slip detection method is-presented and evaluated in different operation conditions. Finally a re-adhesion control scheme is developed based on the Kalman filter. The effectiveness of this approach is demonstrated using comprehensive computer simulations

Advances in Rotating Electric Machines

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

The electromagnetic performance of brushless permanent magnet DC motors - with particular reference to noise and vibration.

A comprehensive analytical technique is developed for predicting the instantaneous magnetic field distribution in radial-field, surface-mounted permanent magnet brushless DC motors under any load condition and commutation strategy. It is based on a 2-dimensional analysis in polar coordinates and accounts implicitly for the corresponding stator winding current waveforms and the effect of stator slot openings. In addition, a 2-dimensional analytical method for calculating the back-emf waveform is presented, whilst the analytical technique is applied to the prediction of the cogging torque waveform and the calculation of the self- and mutual-winding inductances. Also developed and validated is an analytical model for predicting the steady-state dynamic performance of a 3-phase brushless DC drive, by exploiting the periodicity in the stator winding voltage and current waveforms, with due account of the influence of commutation events in the inverter bridge, the back-emf waveform, current limiting, and commutation timing etc. The model is developed further to couple with the motion equation of the rotor to enable the transient and steady-state dynamic performance of brushless DC drives to be predicted. The effect of end-shields on the vibrational behaviour of stators is investigated by the modem modal analysis technique, and new formulae for the calculation of the acoustic power radiated by a cylindrical stator of finite length, using an analytical method, are presented. A technique which combines the finite element method and Fourier analysis to account for the effects of end-shields on the acoustic radiation is developed, and the spherical acoustic radiation model of motors has been improved by the application of finite elements. Finally, a systematic analytical approach to the estimation and analysis of the acoustic noise from a radial-field, internal rotor, brushless DC motor is presented

A Study on the Sensorless Speed Control of Induction Motor using AFE Rectifier

본 논문은 센서로 인한 단점을 보완하기 위해 고안된 유도전동기의 센서리스 제어법에 대하여 다이오드 정류기 대신 AFE 정류기를 이용한 방식을 제안하고자 한다. 이 방식은 기존의 다이오드 정류기를 사용한 방식에 비해 입력전류의 품질을 향상시키고, 역률을 개선하여 전체 시스템의 성능을 높일 수 있다. DFE 정류기는 구조가 간단하고, 특별한 제어가 필요 없다는 장점 때문에 널리 이용되지만, 제어가 불가능한 다이오드의 특성상 입력 전류에 고조파가 많이 함유되어 전체 전력계통에 악영향을 미칠 수 있고 역률 또한 나쁘다. 능동소자를 이용하여 회생 운전이 가능한 AFE 정류기는 입력 전류를 정현파에 가깝게 제어 가능하며 THD 특성을 향상시켜 입력 전류의 품질을 개선할 수 있고, 시스템 안정성이 우수하다. DFE 방식과 달리 위상 천이 변압기가 필요 없기 때문에 구조가 간단하여 시스템의 부피를 줄일 수 있어 설치가 용이하고, 역률 또한 향상시킬 수 있다. 본 논문에서 사용한 센서리스 제어 알고리즘은 전류오차 보상방식이며, 전류제어는 직접토크제어 방식이다. 전류오차보상에 의한 센서리스 속도 제어법은 실제 유도전동기와 수식모델의 고정자전류가 일치하도록 고정자전압을 가하여 전동기의 속도가 설정치인 모델의 속도를 따르도록 만드는 방식이다. 이 방식은 속도를 직접 제어하는 것이 아니라 실제 유도전동기와 수식모델의 전류차를 영으로 수렴시켜 간접적으로 속도를 제어하는 방식이다. 직접토크제어는 토크와 자속을 각각 독립하여 제어하는 방식으로 자속 및 토크의 지령 값과 유도기의 고정자 전압 및 전류 정보를 사용하여 계산한 현재의 자속 및 토크와 비교하여 오차를 산출한 후 제어 정밀도에 따라 폭을 결정하는 히스테리시스 제어기에 입력하고, 출력된 값을 전압벡터의 룩 업 테이블에 입력하여, 오차를 가장 최소화하기 위한 전압벡터를 찾아내어 제어한다. 본 논문에서 제안한 토폴로지의 유효성을 입증하기 위하여 시뮬레이션과 실험을 수행하여 저속영역에서 고속영역에 이르기까지 속도 응답특성이 우수함을 확인하고 중속영역에서 반전속도지령을 가했을 경우, 양호한 응답특성을 확인하였다. 또한 AFE 정류기를 이용한 토폴로지가 DFE 정류기를 이용한 방식보다 입력 전류의 파형이 우수하고, THD 특성 및 역률이 향상되었음을 확인하였다. | This paper proposes a method using the AFE rectifier instead of the diode rectifier for the sensorless control method of the induction motor designed to overcome the disadvantages caused by the sensor. This method improves the quality of the input current and the power factor, thereby improving the performance of the entire system, compared with the conventional diode rectifier method. The DFE rectifier is widely used because of its simple structure and no special control, but due to the nature of the diode that can not be controlled, the input current contains a lot of harmonics, which can adversely affect the entire power system and the power factor is also bad. The AFE rectifier that can regenerate by using the active components can control the input current close to the sinusoidal wave, improve the THD characteristics, improve the input current quality, and have excellent system stability. Unlike the DFE system, it does not need a phase-shifting transformer, which simplifies the structure and reduces the volume of the system, making it easy to install and improve the power factor. The sensorless control algorithm used in this paper is current error compensation method and current control is carried out by direct torque control. The sensorless speed control method by current error compensation is a method of making the speed of the motor follow the speed of the numerical model by applying the stator voltage so that the stator currents of the induction motor and the model are matched. This method does not directly control the speed but indirectly controls the speed by converging the current difference between the induction motor and the numerical model to zero. Direct Torque Control is a method of independently controlling torque and magnetic flux, and it compares the command value of magnetic flux and torque with the current of magnetic flux and torque calculated by using stator voltage and current information of induction machine, then inputs to the hysteresis controller which determines the width according to the control precision and inputs the output value to the lookup table of the voltage vector to find and control the voltage vector for minimizing the error. In order to verify the validity of the proposed topology in this paper, simulation and experiments were carried out to confirm that the speed response characteristics from the low speed range to the high were excellent and good response characteristics were confirmed when the reverse speed command was applied in the middle speed range. Also, it was confirmed that the topology using the AFE rectifier has better input current waveform, THD characteristics and power factor than the DFE rectifier.목 차 ⅰ 그림 목차 ⅲ 표 목차 ⅴ Abstract ⅵ 기호 및 약어 ⅹ 1. 서 론 1 1.1 연구배경 1 1.2 연구 목적과 구성 4 2. 고조파 저감을 위한 컨버터 회로방식 6 2.1 비회생형 회로방식 6 2.2 회생형 회로방식 7 2.3 DFE와 AFE 정류 회로방식 비교 11 3. AFE 정류장치의 전류제어 방식 17 2.1 히스테리시스 방식 17 2.2 삼각파 비교 전류제어 방식 20 2.3 공간벡터전압변조 방식 24 4. 유도전동기의 센서리스 속도제어 방식 35 4.1 속도추정기를 이용한 방식 35 4.2 모델기준적응제어를 이용한 방식 37 4.3 칼만필터를 이용한 방식 39 4.4 슬롯고조파 분석을 이용한 방식 41 4.5 상태궤환 선형화 기법을 이용한 방식 43 4.6 신경회로망을 이용한 방식 47 4.7 고주파 신호주입을 이용한 방식 51 5. AFE 정류기를 이용한 센서리스 속도제어 55 5.1 전류오차수정에의한 센서리스 속도제어방식 55 5.2 직접토크제어 59 5.3 제어 알고리즘 68 6. 시뮬레이션 70 6.1 기존의 DFE 정류기를 이용한 유도전동기의 센서리스 속도제어 71 6.2 제안하는 AFE 정류기를 이용한 유도전동기의 센서리스 속도제어 77 6.3 시뮬레이션 결과 검토 86 7. 실험 및 결과검토 87 7.1 실험장치의 구성 87 7.2 실험결과 검토 91 8. 결 론 100 참고문헌 103Docto

Design of Powder Core Motors

The goal of the study presented in this thesis is to evaluate the advantages and drawbacks of using powder technology in the design of the iron core of small claw-pole electric motors. The use of soft magnetic composites (SMC) and compaction technology allows the creation of complex 3D iron cores. The additional dimension opens for new solutions of the electromechanical energy conversion. A claw-pole motor among the transversal flux machines that has particularly high specific torque is in the focus of research interest. Generally, as the iron core can be more complicated, the winding is chosen to be simpler in the powder core motors. The thesis focuses on the machine design of a single-phase and a two-phase low-power claw-pole motor. The predicted results compare well with measurements of the prototype motors. The motor design process in this thesis uses a magnetic equivalent circuit (MEC) model of the outer-rotor claw-pole motors that is accurate enough to describe the physics of the electromagnetic conversion. Additional equivalent circuits are made to evaluate the mechanic and thermal loading of the machines. The outcome of the equivalent circuit models is enough to estimate roughly the optimal size of the motor and the motor output according to the materials selected. After the rough design process, which is based on equivalent circuits, is finished, a series of FE magnetostatic analyses are made in order to evaluate the static characteristics of the motors, to specify the magnetization losses and to carry out a sensitivity study for the proposed size of the motors. Finally, the magnetic, mechanic and thermal design is analyzed dynamically and statically by the use of coupled multiphysics. The task of the coupled multiphysics is to find out the cooling capability and the thermal limit of the motor as well as the mechanic stress in the motor parts due to magneto-mechanic loading. It is discussed how the discrepancy between the calculated and measured cogging torque depends on the fineness of the 3D FE air gap mesh. Iron loss estimation based on the results of the FE-analysis is made taking the local rotation, and not only pulsation, of the magnetic flux into consideration. It is shown that the loss coefficients in the material model must be adapted to account for flux rotation. A part from the output of the machine as an electromechanical energy converter is their controllability in the electric drive system. Based on the static characteristics, which are calculated in the FE-analysis and verified in prototype measurements, a tailor made control method is developed for the machines designed. Results are presented of extensive simulations and experimental verifications of the proposed control strategy and power electronic circuitry. The high-speed four-pole single-phase motor shows satisfactory results. The other motor, which has 20 poles and two phases, has a main weakness in its complex assembling and a large cogging torque

Studies in Electrical Machines & Wind Turbines associated with developing Reliable Power Generation

The publications listed in date order in this document are offered for the Degree of Doctor of Science in Durham University and have been selected from the author’s full publication list. The papers in this thesis constitute a continuum of original work in fundamental and applied electrical science, spanning 30 years, deployed on real industrial problems, making a significant contribution to conventional and renewable energy power generation. This is the basis of a claim of high distinction, constituting an original and substantial contribution to engineering science

Multi-level-objective design optimization of permanent magnet synchronous wind generator and solar photovoltaic system for an urban environment application

This Ph.D. thesis illustrates a novel study on the analytical and numerical design optimization of radial-flux permanent magnet synchronous wind generators (PMSGs) for small power generation in an urban area, in which an outer rotor topology with a closed-slot stator is employed. The electromagnetic advantages of a double-layer fractional concentration non-overlapping winding configuration are discussed. The analytical behavior of a PMSG is studied in detail; especially for magnetic flux density distribution, time and space harmonics, flux linkages, back-EMF, cogging torque, torque, output power, efficiency, and iron losses computation. The electromagnetic behavior of PMSGs are evaluated when a number of various Halbach array magnetization topologies are presented to maximize the generator’s performance. In addition, the thermal behavior of the PMSG is improved using an innovative natural air-cooling system for rated speed and higher to decrease the machine’s heat mainly at the stator teeth. The analytical investigation is verified via 2-D and 3-D finite element analysis along with a good experimental agreement. Design optimization of electrical machines plays the deterministic role in performance improvements such as the magnetization pattern, output power, and efficiency maximization, as well as losses and material cost minimization. This dissertation proposes a novel multi-objective design optimization technique using a dual-level response surface methodology (D-RSM) and Booth’s algorithm (coupled to a memetic algorithm known as simulated annealing) to maximize the output power and minimize material cost through sizing optimization. Additionally, the efficiency maximization by D-RSM is investigated while the PMSG and drive system are on duty as the whole. It is shown that a better fit is available when utilizing modern design functions such as mixed-resolution central composite (MR-CCD) and mixed-resolution robust (MR-RD), due to controllable and uncontrollable design treatments, and also a Window-Zoom-in approach. The proposed design optimization was verified by an experimental investigation. Additionally, there are several novel studies on vibro-acoustic design optimization of the PMSGs with considering variable speed analysis and natural frequencies using two techniques to minimize the magnetic noise and vibrations. Photovoltaic system design optimization considered of 3-D modeling of an innovative application-oriented urban environment structure, a smart tree for small power generation. The horizon shading is modeled as a broken line superimposed onto the sun path diagram, which can hold any number of height/azimuth points in this original study. The horizon profile is designed for a specific location on the Barcelona coast in Spain and the meteorological data regarding the location of the project was also considered. Furthermore, the input weather data is observed and stored for the whole year (in 2016). These data include, ambient temperature, module’s temperature (open and closed circuits tests), and shading average rate. A novel Pareto-based 3-D analysis was used to identify complete and partial shading of the photovoltaic system. A significant parameter for a photovoltaic (PV) module operation is the nominal operating cell temperature (NOCT). In this research, a glass/glass module has been referenced to the environment based on IEC61215 via a closed-circuit and a resistive load to ensure the module operates at the maximum power point. The proposed technique in this comparative study attempts to minimize the losses in a certain area with improved output energy without compromising the overall efficiency of the system. A Maximum Power Point Track (MPPT) controller is enhanced by utilizing an advanced perturb & observe (P&O) algorithm to maintain the PV operating point at its maximum output under different temperatures and insolation. The most cost-effective design of the PV module is achieved via optimizing installation parameters such as tilt angle, pitch, and shading to improve the energy yield. The variation of un-replicated factorials using a Window-Zoom-in approach is examined to determine the parameter settings and to check the suitability of the design. An experimental investigation was carried out to verify the 3-D shading analysis and NOCT technique for an open-circuit and grid-connected PV module.Esta tesis muestra un novedoso estudio referente al diseño optimizado de forma analítica y numérica de un generador síncrono de imanes permanentes (PMSGs) para una aplicación de microgeneración eólica en un entorno urbano, donde se ha escogido una topología de rotor exterior con un estator de ranuras cerradas. Las ventajas electromagnéticas de los arrollamientos fraccionarios de doble capa, con bobinas concentradas se discuten ampliamente en la parte inicial del diseño del mismo, así como las características de distribución de la inducción, los armónicos espaciales y temporales, la fem generada, el par de cogging así como las características de salida (par, potencia generada, la eficiencia y la distribución y cálculo de las pérdidas en el hierro que son analizadas detalladamente) Posteriormente se evalúan diferentes configuraciones de estructuras de imanes con magnetización Halbach con el fin de maximizar las prestaciones del generador. Adicionalmente se analiza la distribución de temperaturas y su mejora mediante el uso de un novedoso diseño mediante el uso de ventilación natural para velocidades próximas a la nominal y superiores con el fin de disminuir la temperatura de la máquina, principalmente en el diente estatórico. El cálculo analítico se completa mediante simulaciones 2D y 3D utilizando el método de los elementos finitos así como mediante diversas experiencias que validan los modelos y aproximaciones realizadas. Posteriormente se desarrollan algoritmos de optimización aplicados a variables tales como el tipo de magnetización, la potencia de salida, la eficiencia así como la minimización de las pérdidas y el coste de los materiales empleados. En la tesis se proponen un nuevo diseño optimizado basado en una metodología multinivel usando la metodología de superficie de respuesta (D-RSM) y un algoritmo de Booth (maximizando la potencia de salida y minimizando el coste de material empleado) Adicionalmente se investiga la maximización de la eficiencia del generador trabajando conjuntamente con el circuito de salida acoplado. El algoritmo utilizado queda validado mediante la experimentación desarrollada conjuntamente con el mismo. Adicionalmente, se han realizado diversos estudios vibroacústicos trabajando a velocidad variable usando dos técnicas diferentes para reducir el ruido generado y las vibraciones producidas. Posteriormente se considera un sistema fotovoltaico orientado a aplicaciones urbanas que hemos llamado “Smart tree for small power generation” y que consiste en un poste con un generador eólico en la parte superior juntamente con uno o más paneles fotovoltaicos. Este sistema se ha modelado usando metodologías en 3D. Se ha considerado el efecto de las sombras proyectadas por los diversos elementos usando datos meteorológicos y de irradiación solar de la propia ciudad de Barcelona. Usando una metodología basada en un análisis 3D y Pareto se consigue identificar completamente el sistema fotovoltaico; para este sistema se considera la temperatura de la célula fotovoltaica y la carga conectada con el fin de generar un algoritmo de control que permita obtener el punto de trabajo de máxima potencia (MPPT) comprobándose posteriormente el funcionamiento del algoritmo para diversas situaciones de funcionamiento del sistemaLa tesis desenvolupa un nou estudi per al disseny optimitzat, analític i numèric, d’un generador síncron d’imants permanents (PMSGs) per a una aplicació de microgeneració eòlica en aplicacions urbanes, on s’ha escollit una configuració amb rotor exterior i estator amb ranures tancades. Es discuteixen de forma extensa els avantatges electromagnètics dels bobinats fraccionaris de doble capa així com les característiques resultats vers la distribució de les induccions, els harmònics espacials i temporals, la fem generada, el parell de cogging i les característiques de sortida (parell, potencia, eficiència i pèrdues) Tanmateix s’afegeix l’estudi de diferents estructures Halbach per als imants permanents a fi i efecte de maximitzar les característiques del generador. Tot seguit s’analitza la distribució de temperatures i la seva reducció mitjançant la utilització d’una nova metodologia basada en la ventilació natural. Els càlculs analítics es complementen mitjançant anàlisi en 2 i 3 dimensions utilitzant elements finits i diverses experiències que validen els models i aproximacions emprades. Una vegada fixada la geometria inicial es desenvolupen algoritmes d’optimització per a diverses variables (tipus de magnetització dels imants, potencia de sortida, eficiència, minimització de pèrdues i cost dels materials) La tesi planteja una optimització multinivell emprant la metodologia de superfície de resposta i un algoritme de Booth; a més, es realitza la optimització considerant el circuit de sortida. L’algoritme resta validat per la experimentació realitzada. Finalment, s’han considerat diversos estudis vibroacústic treballant a velocitat variable, emprant dues tècniques diferents per a reduir el soroll i les vibracions desenvolupades. Per a finalitzar l’estudi es considera un sistema format per una turbina eòlica instal·lada sobre un pal de llum autònom, els panells fotovoltaics corresponents i el sistema de càrrega. Per a modelitzar l’efecte de l’ombrejat s’ha emprat un model en 3D i les dades del temps i d’irradiació solar de la ciutat de Barcelona. El model s’ha identificat completament i s’ha generat un algoritme de control que considera, a més, l’efecte de la temperatura de la cèl·lula fotovoltaica y la càrrega connectada al sistema per tal d’aconseguir el seguiment del punt de màxima potenciaPostprint (published version