Reluktanssiverkkomalli kestomagneettitahtikoneen staattisen ilmavälivuontiheyden mallinnukseen

Kaikissa pyörivissä sähkömoottoreissa vääntömomentin tuoton kannalta olennainen magneettivuo kulkee staattorin ja roottorin välillä ilmavälin kautta. Ilmaväli mallinnetaan koneensuunnittelun yhteydessä tämän vuoksi tarkasti. Elementtimenetelmällä voidaan analysoida moottoreita varsin tarkasti, mutta menetelmän käyttö vie paljon aikaa ja sovittaminen muihin laskentaympäristöihin on usein hankalaa. Tämän vuoksi voidaan käyttää riittävän tarkkuuden omaavia analyyttisiä laskentamenetelmiä, joiden sovittaminen muihin ohjelmaympäristöihin on helpompaa kuin elementtimenetelmää käytettäessä. Diplomityössä kehitetään reluktanssiverkkomalli kestomagneettien aikaansaaman ilmavälivuontiheyden mallintamiseen kestomagneettitahtikoneille, joissa on pinta-asennetut kestomagneetit. Kehitetyn reluktanssiverkkomallin toimivuutta vertaillaan muihin ilmavälivuontiheyden laskentamenetelmiin.

Sähköisen liikkeenohjauskäytön mitoitus, käyttöönoton dokumentointi ja pakkauslinjasovellukset

Frequency converters have started to gain new market areas in the field of motion control applications. The communication and control properties of frequency converters have reached the properties of traditional servo amplifiers during the past few years. In this thesis a motion control system was examined. This particular system consists of frequency converters, permanent magnet synchronous motors and linear belt drives. The properties and prerequisites for packing are discussed. A test setup was build and measurement sets were done to examine the performance of the system. Speed and accuracy measurements were done in all three dimensions. Based on the measurement results applicability of the system for packing industry was evaluated.

On the Analysis and Control of a Linear Synchronous Servomotor with a Flexible Load

Industry's growing need for higher productivity is placing new demands on mechanisms connected with electrical motors, because these can easily lead to vibration problems due to fast dynamics. Furthermore, the nonlinear effects caused by a motor frequently reduce servo stability, which diminishes the controller's ability to predict and maintain speed. Hence, the flexibility of a mechanism and its control has become an important area of research. The basic approach in control system engineering is to assume that the mechanism connected to a motor is rigid, so that vibrations in the tool mechanism, reel, gripper or any apparatus connected to the motor are not taken into account. This might reduce the ability of the machine system to carry out its assignment and shorten the lifetime of the equipment. Nonetheless, it is usually more important to know how the mechanism, or in other words the load on the motor, behaves. A nonlinear load control method for a permanent magnet linear synchronous motor is developed and implemented in the thesis. The purpose of the controller is to track a flexible load to the desired velocity reference as fast as possible and without awkward oscillations. The control method is based on an adaptive backstepping algorithm with its stability ensured by the Lyapunov stability theorem. As a reference controller for the backstepping method, a hybrid neural controller is introduced in which the linear motor itself is controlled by a conventional PI velocity controller and the vibration of the associated flexible mechanism is suppressed from an outer control loop using a compensation signal from a multilayer perceptron network. To avoid the local minimum problem entailed in neural networks, the initial weights are searched for offline by means of a differential evolution algorithm. The states of a mechanical system for controllers are estimated using the Kalman filter. The theoretical results obtained from the control design are validated with the lumped mass model for a mechanism. Generalization of the mechanism allows the methods derived here to be widely implemented in machine automation. The control algorithms are first designed in a specially introduced nonlinear simulation model and then implemented in the physical linear motor using a DSP (Digital Signal Processor) application. The measurements prove that both controllers are capable of suppressing vibration, but that the backstepping method is superior to others due to its accuracy of response and stability properties.

Eddy-current losses in rotor surface mounted permanent magnets

The aim of the work is to study the existing analytical calculation procedures found in literature to calculate the eddy-current losses in surface mounted permanent magnets within PMSM application. The most promising algorithms are implemented with MATLAB software under the dimensional data of LUT prototype machine. In addition finite elements analyze, utilized with help of Flux 2D software from Cedrat Ltd, is applied to calculate the eddy-current losses in permanent magnets. The results obtained from analytical methods are compared with numerical results.

Electrical machine in a Hybrid Electrical Vehicle

Hybrid electric vehicles (HEV) have attracted very much attention during the latest years. Increasing environmental concern and an increase in fuel prices are key factors for the growing interest towards the HEV. In a hybrid electric vehicle the power train consists of both a mechanical power system and an electric power transmission system. The major subsystems in the mechanical power system are the internal combustion engine which powers the vehicle; electric power transmission including an energy storage, power electronic inverter, hybrid control system; the electric motor drive that runs either in the generating mode or in the motoring mode to process the power flow between the energy storage and the electrical machine. This research includes two advanced electric motors for a parallel hybrid: induction machine and permanent magnets synchronous machine. In the thesis an induction motor and a permanent magnet motor are compared as propulsion motors. Electric energy storages are also studied.

Design Aspects of Megawatt-Range Direct-Driven Permanent MagnetWind Generators

Direct-driven permanent magnet synchronous generator is one of the most promising topologies for megawatt-range wind power applications. The rotational speed of the direct-driven generator is very low compared with the traditional electrical machines. The low rotational speed requires high torque to produce megawatt-range power. The special features of the direct-driven generators caused by the low speed and high torque are discussed in this doctoral thesis. Low speed and high torque set high demands on the torque quality. The cogging torque and the load torque ripple must be as low as possible to prevent mechanical failures. In this doctoral thesis, various methods to improve the torque quality are compared with each other. The rotor surface shaping, magnet skew, magnet shaping, and the asymmetrical placement of magnets and stator slots are studied not only by means of torque quality, but also the effects on the electromagnetic performance and manufacturability of the machine are discussed. The heat transfer of the direct-driven generator must be designed to handle the copper losses of the stator winding carrying high current density and to keep the temperature of the magnets low enough. The cooling system of the direct-driven generator applying the doubly radial air cooling with numerous radial cooling ducts was modeled with a lumped-parameter-based thermal network. The performance of the cooling system was discussed during the steady and transient states. The effect of the number and width of radial cooling ducts was explored. The large number of radial cooling ducts drastically increases the impact of the stack end area effects, because the stator stack consists of numerous substacks. The effects of the radial cooling ducts on the effective axial length of the machine were studied by analyzing the crosssection of the machine in the axial direction. The method to compensate the magnet end area leakage was considered. The effect of the cooling ducts and the stack end area effects on the no-load voltages and inductances of the machine were explored by using numerical analysis tools based on the three-dimensional finite element method. The electrical efficiency of the permanent magnet machine with different control methods was estimated analytically over the whole speed and torque range. The electrical efficiencies achieved with the most common control methods were compared with each other. The stator voltage increase caused by the armature reaction was analyzed. The effect of inductance saturation as a function of load current was implemented to the analytical efficiency calculation.

Kestomagneettitahtikonekäyttöjen erot

Permanent magnet drives with nominal power over 10 kW were not a cost-sufficient system 25 years ago due to high material expenses. The improvements in motor drives, the rise in competition and the tightening of standards and regulations have caused that the PM-drives are more and more common in the over 10 kW nominal power range. The goal of this thesis is to research the performance in relation to nominal power of a PM-drive technique that is vastly increasing its popularity in fan related devices. The studied motor technique brushless direct current drive (BLDC) consists of a voltage source inverter, permanent motor and six-step-control. The reference drive is a brushless alternating current drive (BLAC) which consists of a VSI, PM and a hysteresis control. As a conclusion there are no major obstacles that would impede the BLDC-drive technique from expanding to larger power stages. The following factors must be taken into consideration when designing a BLDC-drive: motor’s current change rate, inverter switching frequency, motor’s nominal electric frequency, phase inductance and the current handling capability of the inverter. The fluctuating material costs create instability to the end prices of PM-motors that can in the worst case lead to diminished interest towards BLDC- and PM-drives in general.

Kestomagnetoidun roottorin mekaniikkasuunnittelu ja -analysointi

Työssä kehitettiin suurnopeuskäyttöön soveltuva kestomagnetoitu roottori olemassa olevan induktiokoneen staattorirunkoon. Kehitystyön tarkoituksena oli selvittää roottorin mekaaniset raja-arvot, kuten maksimi kehänopeus. Samalla otettiin kantaa myös tarvittaviin analysointi- ja mitoitusmenetelmiin. Maksimi kehänopeuden, laakeroinnin ja roottorin skaalattavuuden selvittäminen edellytti myös tarkkaa materiaaliselvitystä ja optimointia. Tästä syystä työn aikana tehtiin tiivistä yhteistyötä materiaalitoimittajien kanssa. Työn tuloksena syntyi uusi menetelmä toteuttaa radiaalisen magneettivuon luova kestomagneettiroottori 200 m/s kehänopeudelle. Suunniteltua roottoriratkaisua käytetään testausroottorina, jolla selvitetään valmistuksen, kokoonpanon ja sähkötehon rajoitteet käytännössä. Suunnittelutyö edellyttikin jatkuvaa iterointia sähkösuunnittelun ja roottorin osien valmistajien kanssa, jotta löydettiin paras kompromissiratkaisu roottorin prototyyppiin. Tämän seurauksena saatiin luotua varsin tarkat suunnittelu- ja analysointiraja-arvot kestomagneettiroottorin tuotteistettavia versioita varten.

Hysteresis Losses in Sintered NdFeB Permanent Magnets in Rotating Electrical Machines

Permanent magnet materials are nowadays widely used in the electrical machine manufacturing industry. Eddy current loss models of permanent magnets used in electrical machines are frequently discussed in research papers. In magnetic steel materials we have, in addition to eddy current losses, hysteresis losses when AC or a rotating flux travels through the material. Should a similar phenomenon also be taken into account in calculating the losses of permanent magnets? Actually, every now and then authors seem to assume that some significant hysteresis losses are present in rotating machine PMs. This paper studies the mechanisms of possible hysteresis losses in PMs and their role in PMs when used in rotating electrical machines.

Kaksoiskäämitty hybridibussin kestomagneettiajomoottori

Tämä työ on tehty Lappeenrannan teknilliselle yliopistolle, joka on suunnitellut ja toteuttanut hybridibussin. Hybridibussin ajomoottorissa käytetään kaksoiskäämitystä, joka mahdollistaa bussin ajamisen vikatilanteessa, jossa toinen käämityksistä on epäkunnossa. Työn tavoitteena on selvittää, millainen kaksoiskäämitys toimii parhaiten tämän hybridibussin kestomagneettiajomoottorissa. Työssä tutustutaan ajomoottoreihin ja niiltä vaadittaviin ominaisuuksiin sekä vikasietoisiin sähkömoottoreihin. Tutkimuksessa löydettyihin vikasietoisiin ajomoottoreihin perustuen päädyttiin neljään kaksoiskäämitysvaihtoehtoon. Näitä kaksoiskäämityksiä tutkittiin FE-analyysiä hyödyntäen. Kaksoiskäämitysten toimintaa simuloitiin nimellis- ja vikatilanteessa. Simuloinnin tuloksista selvisi, että kaksoiskäämitys, jossa jokaisessa urassa oli puolet yhtä käämitystä ja puolet toista (kaksoiskäämitys 1), ei toiminut kunnolla nimellistilanteessa eikä vikatilanteessa. Suurin ongelma oli vikatilanteessa aiheutuva suuri oikosulkuvirta. Kaksoiskäämitys, jossa kaksi napaa oli samaa käämitystä (kaksoiskäämitys 2), toimi moitteettomasti nimellistilanteessa. Vikatilanteen toiminnassa kuitenkin havaittiin epäjaksollisuutta magneettivuontiheydessä, mikä on haitallista moottorin käynnille ja vaaraksi roottorille. Kaksoiskäämityksiä, joista ensimmäisessä oli neljäsosa konetta samaa käämitystä (kaksoiskäämitys 3) ja toisessa puolet koneesta samaa käämitystä (kaksoiskäämitys 4), tutkittiin vikatilanteessa vain magneettivuontiheyden osalta. Puolet ja puolet käämityn koneen osalta magneettivuontiheys osottautui epäjaksolliseksi kuten oli odotettu. Neljäsosiksi käämityn koneen magneettivuontiheys oli säännöllisen jaksollinen. Nimellispisteessä kaksoiskäämityksillä 3 ja 4 havaittiin suuri vääntöväre verrattuna kaksoiskäämityksiin 1 ja 2. Johtopäätöksenä kaksoiskäämitys 3 vaikuttaa lupaavalta, mikäli suuri nimellispisteen vääntöväre saadaan hallintaan käyttämällä uravinoutta staattorissa.

A Novel Slotless PMBLDC Motor for Precise Positioning Applications

This paper presents the design and analysis of a novel machine family of Siotiess Permanent Magnet Brushless DC motors (PMBLDC) for precise positioning applications of spacecrafts. Initial design, selection of major parameters and air gap magnetic flux density are estimated using the analytical model of the machine. The proportion of the halbach array in the machine was optimized using FE to obtain near trapezoidal flux pattern. The novel machine topology is found to deliver high torque density, high efficiency, zero cogging torque, better positional stability, high torque to inertia ratio and zero magnetic stiction suiting space requirements. The machine provides uniform air gap flux density along the radius thus avoiding circulating currents in stator conductors and hence reducing torque ripple

Conversor CA-CA de elevado fator de potência para aplicações com geradores de Ímã permanente

This paper proposes and describes a high power factor AC-AC converter for naval applications using Permanent Magnet Generator (PMG). The three-phase output voltages of the PMG vary from 260 Vrms (220 Hz) to 380 Vrms (360 Hz), depending on load conditions. The proposed converter consists of a Y-/ΔY power transformer, which provides electrical isolation between the PMG and remaining stages, and a twelve-pulse uncontrolled rectifier stage directly connected to a single-phase inverter stage, without the use of an intermediary DC-DC topology. This proposal results in more simplicity for the overall circuitry, assuring robustness, reliability and reduced costs. Furthermore, the multipulse rectifier stage is capable to provide high power factor and low total harmonic distortion for the input currents of the converter. The single-phase inverter stage was designed to operate with wide range of DC bus voltage, maintaining 120 Vrms, 60 Hz output. The control philosophy, implemented in a digital signal processor (DSP) which also contains protection routines, alows series connections between two identical converters, achieving 240 Vrms, 60 Hz total output voltage. Measured total harmonic distortion for the AC output voltage is lower than 2% and the input power factor is 0.93 at 3.6kW nominal load. © 2010 IEEE.

Estudo da topologia de motores de fluxo axial de excitação híbrida com foco na utilização em tração elétrica.

Os motores de corrente contínua convencionais são muito bem conhecidos pela sua robustez e pelo seu alto nível de controlabilidade, alem do fato de possibilitarem a operação na região de enfraquecimento de campo (modo motor), quando esta situação se fizer necessária. Por estas características, as máquinas de corrente contínua ainda são empregadas nos dias atuais em nichos específicos de utilização. Não obstante, a máquina c.c. apresenta algumas desvantagens, principalmente a intensiva e dispendiosa manutenção eletromecânica necessária para sua operação. Como opção de sanar este problema, surgiram na década de 60, as máquinas elétricas de corrente contínua sem escovas (brushless) com excitação por ímãs permanentes de fluxo trapezoidal. O problema destas máquinas se deve justamente a impossibilidade da variação de fluxo de excitação uma vez que são produzidos puramente pelos ímãs. Sendo assim, este trabalho tem como propósito, o estudo de topologias diferenciadas da máquina elétrica, através de um circuito magnético não convencional para aplicação e utilização em sistemas de tração elétrica para operação na região de enfraquecimento de campo através da variação do fluxo resultante no entreferro. Como objeto de estudo, foi focada a topologia de fluxo axial com excitação híbrida, ou seja, dupla excitação (excitação a ímãs permanentes e excitação elétrica). Para o projeto da topologia proposta, nesta tese, adicionalmente ao método analítico, foram realizadas simulações computacionais para a comparação e refinamento dos resultados das grandezas eletromagnéticas da máquina.

Application of calorimetric method for loss measurement of a SynRM drive system

Synchronous reluctance motors (SynRMs) are gaining in popularity in industrial drives due to their permanent magnet-free, competitive performance, and robust features. This paper studies the power losses in a 90-kW converter-fed SynRM drive by a calorimetric method in comparison of the traditional input-output method. After the converter and the motor were measured simultaneously in separate chambers, the converter was installed inside the large-size chamber next to the motor and the total drive system losses were obtained using one chamber. The uncertainty of both measurement methods is analyzed and discussed.

Entwicklung eines Lineardirektantriebs für Transportbänder

Transportbandsyteme werden im Bereich der Intralogistik zur Förderung von Stück- sowie leichten Schüttgütern eingesetzt. Der Antrieb der Transportbänder erfolgt dabei üblicherweise kraftschlüssig über die Antriebstrommel. Der Einsatz von Lineardirektantrieben ermöglicht als Antriebsalternative die Erzeugung der Vorschubkräfte und die Krafteinleitung in das Transportband über der Länge des Lineardirektantriebs verteilt. Dadurch lässt sich die Transportbandvorspannung erheblich reduzieren und damit auch ein leichteres und kostengünstigeres Transportband im Vergleich zu konventionellen Antriebskonzepten verwenden. Basierend auf vorherigen Untersuchungen wurde ein Lineardirektantrieb auf Basis eines Hybridmotors entwickelt, welcher die Vorteile permanentmagneterregter Maschinen mit denen der Reluktanzmotorprinzipien vereint. Auf Grundlage der durch Simulation ermittelten Kraftentfaltkungscharakteristik des Linearmotors auf die Läuferelemente wurden verschiedene Konzepte zur Befestigung dieser Läuferelemente entwickelt, untersucht und erprobt. Aufgrund der Elastizität von Transportbändern sind zudem alternative Führungskonzepte erforderlich, da geometrische Abweichungen der am Transportband befestigten Läuferelemente zu hohen Verlusten durch Reibung führen. Unterschiedliche Führungskonzepte, belegt durch Messungen, geben einen Ausblick auf den linearmotorischen Antrieb.