Thanks to development of power semiconductor devices and integrated circuits, active front-end converters with controllability of bidirectional power flow have become popular and viable in industrial applications. This thesis proposes an improved resonant current control for the active front-end converter with LCL filter. The proposed control consists of a band-pass filter tuned at fundamental frequency and various band-rejected filters resonant at harmonic frequencies to provide fundamental current tracking capability as well as enhance harmonic current rejection. Based on this algorithm, the active front-end converter can control dc voltage with unity power factor by sensing converter output current, LCL filter voltage and dc voltage. This approach also conducts harmonic current rejection under distorted line voltage with no phase-locked-loop used, which is the significant advantage in terms of phase lag of frame transformation and computing effort of digital signal processing. Current tracking performance and harmonic rejection capability of the proposed method are verified based on frequency-domain analysis. Computer simulations and experimental results are also implemented to validate effectiveness.

This master's thesis is divided into two parts. The first part concerns the development of a simulation model of a current controller and a physical drive unit, both implemented in Simulink with the use of legacy code and regulated with field oriented control. The second part concerns the development of a dead-time compensation algorithm. The dead-time is a small delay added to the pulse width modulation signal to diminish the risk of a short circuit in the power electronics. The dead-time causes a voltage distortion, resulting in distorted phase currents, a lower bandwidth and ultimately a decreased machine accuracy. The new simulation environment was able to simulate a real life scenario with promising results. Hence, it could be used to evaluate the dead-time compensation algorithms. Three different dead-time compensation algorithms were implemented and they all showed an increased smoothness of the phase currents as well as an increased controller bandwidth. Both these features are desirable outcomes and all three algorithms show potential to improve accuracy when implemented in a real system.

Dans le domaine du véhicule électrique, la chaîne de traction allant de la batterie de stockage aux roues en passant par le moteur constitue le cœur du système. Elle bénéficie régulièrement d’innovations technologiques rendant ce véhicule de plus en plus attractif. Actuellement, les motorisations proposées par les constructeurs sont classiques, de type synchrone à rotor bobiné, à aimant permanent ou asynchrone. De conception éprouvée et dotées de lois de commande complexes et parfaitement maîtrisées, elles offrent de bonnes performances.Cependant, les industriels explorent de nouvelles motorisations moins conventionnelles permettant de réduire leur coût de fabrication, tout en maintenant les performances. Une des solutions possibles est la machine à réluctance variable à double saillance (MRVDS). En effet, elle est de conception simple et constituée de matériaux peu couteux. Son rotor complètement passif lui confère une très bonne robustesse et une vitesse de rotation élevée, nécessaire à une certaine compacité.Néanmoins, son pilotage est beaucoup plus complexe que pour les autres machines, elle est relativement bruyante et son couple présente des ondulations non négligeables.Nos travaux ont pour but de contribuer à l’amélioration des performances de la MRVDS du point de vue contrôle, caractéristiques de couple et efficacité énergétique sur une plage de vitesse importante. Ils ont alors été conduits selon deux axes : un axe commande et un axe conception.Afin de satisfaire un contrôle du couple le plus parfait possible, de nouveaux régulateurs de courant à la fois performants et relativement simples à implémenter sur cible logicielle ont été présenté dans un premier temps. Ensuite, nous avons proposé une implémentation partitionnée de la commande de la MRVDS sur cibles logicielle et matérielle. L’objectif est ici de conserver les performances de la commande dans le cas de l’utilisation d’un processeur économique, dont la période d’échantillonnage serait relativement importante, et tout particulièrement à haute vitesse. Une carte FPGA (Fied Programmable Gate Array) a alors été mise en œuvre.Pour améliorer les caractéristiques de couple en fonction de la vitesse ainsi que le rendement de l’ensemble moteur-convertisseur, une nouvelle structure de MRVDS non conventionnelle a été proposée. Elle est munie d’un bobinage auxiliaire créant une excitation magnétique dans chaque phase.Une étude a d’abord été menée à l’aide de simulations basées sur un nouveau modèle. Elle a permis de mettre en évidence les avantages d’une excitation par rapport à une MRVDS classique. Afin de valider les résultats, un prototype a ensuite été conçu, réalisé et expérimenté.Une part importante de ces travaux a ainsi été consacrée à la mise en œuvre de plateformes expérimentales et à la réalisation de nombreux essais permettant de valider les développements théoriques, tant du point de vue commande sur une MRVDS 8/6 que conception sur une MRVDS 6/4. / For electric vehicles, traction from storage battery to the wheels through the engine is the heart of the system. It regularly enjoys technological innovations making this vehicle more attractive. Currently, machines offered by manufacturers are classic, synchronous and induction machines. With complex laws, they offer good performance.However, manufacturers are exploring new unconventional machines to reduce their manufacturing cost while maintaining performance. One possible solution is the switched reluctance machine (SRM). Indeed, its design is simple and made of inexpensive materials. Its rotor completely passive gives it a very good robustness and high rotational speed required for certain compactness. However, its operation is much more complex than for other machines, it is relatively noisy and has significant torque ripple.Our work contributes to the improvement of SRM’s performance in terms of control torque characteristics and global efficiency over a large range speed. They were driven on two axes: one control axis and one design axis.To satisfy a torque control as perfect as possible, new currents controller both efficient and relatively simple to implement on software target were first presented. Then we proposed a SRM's control implementation on hardware and software targets. The objective is to maintain the performances in the case of an important sampling period, especially at high speeds. So an FPGA circuit (Fied Programmable Gate Array) was used.To improve torque characteristics depending on the speed, and global efficiency, a new SRM structure has been proposed. It is provided with an auxiliary coil creating a magnetic excitation in each phase. A study was initially conducted using simulations based on a new model. It helped to highlight the benefits of excitement compared to a conventional SRM. To validate the results, a prototype was then designed, built and tested.An important part of this work has been devoted to the implementation of experimental platforms and implementation of numerous tests to validate the theoretical developments, both in terms of control on a 8/6 SRM and design on a 6/4 SRM.

This thesis deals with the analysis of the actuator ACOPOS and its accessories. There are described the cascaded control loop concept and the setting servomechanism from B&R Automation with the important parameters. We follow the draft a speed controller servomotor with a load with the regards to knowledge of the control system. We compare the different methods of labor control actuator at last. There are implemented laboratory tasks of Position servomechanism and speed servo controller-on-load as a demonstration of our achieved results.

Goal of this semestral thesis is to design power converter which is to be used for measurement. The converter consists of two forward converters in push-pull topology. The converter is to behave as a constant current source with maximum open-circuit voltage of 1000V. Maximum current is 5A. The current range is split into three sub-ranges, to meet the strict requirements on ripple current. The range of currents is 0-5A. The operating frequency of converter is 34KHz. The converter will be charged using two portable electric generators with output voltage 230V.

The continuously increasing energy penetration from wind farms into the grid raises concerns regarding power quality and the stable operation of the power system. The Grid Code´s requirements give strict guidelines for a wind farm´s behaviour under faulty or abnormal operating conditions.The primary purpose of this project is the application of a STATCOM for wind farm integration complying with the Grid Code. Towards that, an outer control strategy for the converter is designed so as to regulate the voltage at the point of common coupling by providing reactive power compensation. Thus the safe operation of the grid will be ensured since the wind farm will follow the Grid Code´s standards.The existing Grid Code requires only a positive sequence current controller. This study attempts to investigate whether this is sufficient or not and to examine the possibility of extending the Grid Code requirements so as to incorporate a negative sequence current controller as well. The results support the latter suggestion. Also, the use of SiC devices was also considered in this project. / Den ständigt ökande penetrationen av vindenergi i elnätet väcker farhågor om elkvalitet och stabil drift av kraftsystemet. Nätkoden (Grid Code) ger strikta riktlinjer för en vindkraftsparks beteende i felfall och under onormala driftsförhållanden.Huvudsyftet med detta projekt är att använda en STATCOM för integration av vindkraftsparker så att nätkoden uppfylls. I detta projekt utformas en yttre reglerstrategi för omriktaren för att reglera spänningen vid anslutningspunkten för vindkraftsparken genom att tillhandahålla reaktiv effektkompensering. Därigenom uppnås en säker drift av nätet eftersom vindkraftparken kommer att följa nätkoden.Den befintliga nätkoden kräver endast styrning av plusföljdskomponenten av strömmen. Denna studie försöker undersöka om detta är tillräckligt samt undersöka möjligheten för att utvidga nätkoden genom att införa ett krav på styrning av negativ-sekvens ström. Resultaten stöder det sistnämnda förslaget. Även användningen av halvledarkomponenter av kiselkarbid-SiC studerades i detta projekt.

In this thesis, the basics of electromagnetic theory for wave-energy conversion are reviewed, some of the characteristics of the ocean wave are investigated, some of the power take-off (PTO) systems are introduced, and details about linear permanent magnetic machines, in particular, are discussed.  The thesis aims to model the novel linear transverse flux machine designed by Anders Hagnestål and to build hysteresis current controller for power factor correc- tion. Although this machine is expected to have high performance in terms of efficiency, it also exhibits a strong mutual interaction between the three phases of the machine. Thus, simplification of the actual model of the machine is im- posed to mitigate the complexity of the machine and facilitate the Simulink model. Four cases of the double band hysteresis control are studied. The cur- rents seem to be responding properly to the control scheme; however, software and hardware programming of a microprocessor would be preferable to ensurethe applicability of the control strategy in a real environment. / I detta examensarbete undersöks elektromagnetisk teori och havsvågors egenskaper. Några energiomvandlingssystem introduceras och permanentmagnetiserade maskiner diskuteras i detalj. Syftet med avhandlingen är att modelleraen ny linjär transversalflödesmaskin som är designad av Anders Hagnestål och att bygga en hysteresbaserad strömkontroll för denna. Även om maskinen förväntas prestera bra, uppvisar den också en stark ömsesidig magnetisk interaktion mellan de tre faserna. För att kunna hantera detta problem och därmed kunna genomföra simuleringar införs en förenklad elektromagnetisk modell av maskinen. En strömkontroller har implementerats i Simulink, där fyra fall av dubbelbandshystereskontroll studerats. Resultaten från simuleringarna visar att strömkontrollern fungerar. Nästa steg i projektet är att utföra mjukvaru och hårdvaruprogrammering av en mikrokontroller för att testa systemet i enverklig miljö.

In DC to AC power conversion, voltage source inverters (VSI) based current controllers are usually preferred for today’s high performance AC drive which requires excellent dynamic and steady state performances at different transient and load conditions, with the additional advantages like inherent short circuit and over current protection. Out of different types of current controllers, hysteresis controllers are widely used due to their simplicity and ability to meet the requirements for a high performance AC drives. But the conventional hysteresis controllers suffers from wide variation of PWM switching frequency, overshoot in current errors, sub-harmonic components in the current waveform and non-optimum switching at different operating point of the drive system. To mitigate these problems, particularly to control the switching frequency variation, which is the root cause of all other problems, several methodologies like ramp comparison based controller, predictive current controller, etc. were proposed in the literature. But amplitude and phase offset error in the ramp comparison based controllers and complexities involved in the predictive controllers have limited the use of these controllers. Moreover, these type of controllers, which uses three separate and independently controlled tolerance band (sinusoidal type or adaptive) to control the 3-phase currents, shows limited dynamic responses and they are not simple to implement. To tackle the problem of controlling 3-phase currents simultaneously, space vector based hysteresis current controller is very effective as it combines the current errors of all the three phases as a single entity called current error space vector. It has a single controller’s logic with a hysteresis boundary for controlling this current error space vector. Several papers on space vector based hysteresis controllers for 2-level inverter with constant switching frequency have been published, but the application of the constant switching frequency based hysteresis current controllers for multi¬level inverter fed drive system, has not been addressed properly. Use of multi-level inverter in modern high performance drive for medium and high voltage levels is more prominent because of multi-level’s inherent advantages like good power quality, good electromagnetic compatibility (EMC), better DC link voltage utilization, reduced device voltage rating, so on. Even though some of the earlier works describe three-level space vector based hysteresis current controller techniques, they are specific to the particular level of inverters and does not demonstrate constant switching frequency of operation. This thesis proposes a novel approach where nearly constant switching frequency based hysteresis controller can be implemented for any general n-level inverter and it is also independent of inverter topology. In this work, varying parabolic boundary is used as the hysteresis current error boundary for controlling the current in a multi-level space vector structure. The computation of the parabolic boundary is accomplished offline and all the necessary boundary parameters at different operating points are stored in the look-up tables. The varying parabolic boundary for the multi-level space vector structure depends on the sampled reference phase voltage values which are estimated from stator current error information and then using the equivalent circuit model of induction motors. Here, a mapping technique is adopted to bring down all the three phase references to the inner- most carrier region, which results in mapping any outer triangular structure where tip of the voltage space vector is located, to one of the sectors of the inner most hexagon of the multi-level space vector structure. In this way, the required mapped sector information is easily found out to fix the correct orientation of the parabolic boundary in the space vector plane. This mapping technique simplifies the controller’s logic similar to that of a 2-level inverter. For online identification of the inverter switching voltage vectors constructing the present outer triangle of the multi-level space vector structure, the proposed controller utilizes the sampled phase voltage references. This identification technique is novel and also generic for any n-level inverter structure. This controller is having all the advantages of a space vector based hysteresis current controller and that of a multi-level inverter apart from having a nearly constant switching frequency spectrum similar to that of a voltage controlled space vector PWM (VC-SVPWM). Using the proposed controller, simulation study of a five-level inverter fed induction motor (IM) drive scheme, was carried out using Matlab-Simulink. Simulation study showed that the switching frequency variations in a fundamental cycle and over the entire speed range of the linear modulation region, is similar to that of a VC-SVPWM based multi-level VSI. The proposed hysteresis controller is experimentally verified on a 7.5 kW IM vector control drive fed with a five-level VSI. The proposed current error space vector based hysteresis controller providing nearly constant switching frequency is implemented on a TI TMS320LF2812 DSP and Xilinx XC3S200FT256 FPGA based platform. The three-phase reference currents are generated depending on the frequency command and the controller is tested with the drive for the entire operating speed range of the machine in forward and reverse directions. Steady state and quick transient results of the proposed drive are presented in this thesis. This thesis also proposes another type of hysteresis controller, firstly for 2-level inverter and then for general n-level multi-level inverter, which eliminates the parabolic boundary and replaces it with a boundary which is computed online and does not use any look up table for boundary selection. The current error boundary for the proposed hysteresis controller is computed online in a very simple way, using the information of estimated fundamental stator voltages along α and β axes of space vector plane. The method adopted for the proposed controller to compute the boundary does not involve any complicated computations and it selects the optimal vector for switching when current error space vector crosses the boundary. This way adjacent voltage vector switching similar to VC-SVPWM can be ensured. For 2-level inverter, it precisely determines the sector, in which reference voltage vector is present. In multi-level inverter, this controller also finds out the mapped sector information using the same mapping techniques as explained in the first part of this thesis. In both 2-level and multi-level inverter, the proposed controller does not use any look up table for finding individual voltage vector switching times from the estimated voltage references. These switching times are used for the computation of hysteresis boundary for individual vectors. Thus the hysteresis boundary for individual vectors is exactly calculated and the boundary is similar to that of VC-SVPWM scheme for the respective levels of inverter. In the present scheme, the phase voltage harmonic spectrum is very close to that of a constant switching frequency VC-SVPWM inverter. In this thesis, at first, the proposed on line boundary computation scheme is implemented for a 2-level inverter based controller for the initial study, so that it can be executed as fast as 10 µs in a DSP platform, which is required for accurate current control. Then the same algorithm of 2-level inverter is extended for multi-level inverter with the additional logic for online identification of nearest switching voltage vectors (also used in the parabolic boundary case) for the present sampling interval. Previously mentioned mapping technique for multi-level inverter, is also implemented here to bring down the phase voltage references to the inner-most carrier region to realize the multi-level current control strategy equivalent to that of a 2-level inverter PWM current control. Simulation study to verify the steady state as well as transient performance of the proposed controller for both 2-level as well as five-level VSI fed IM drive is carried out using Simulink tool box of MATLAB Simulation Software. The proposed hysteresis controllers are experimentally verified on a 7.5 kW IM vector control drive fed with a two-level VSI and five-level VSI separately. The proposed current error space vector based hysteresis controller providing nearly constant switching frequency profile for phase voltage is implemented on the TI TMS320LF2812 DSP and Xilinx XC3S200FT256 FPGA based platform. The three-phase reference currents are generated depending on the frequency command and the proposed hysteresis controllers are tested with drive for the entire operating speed range of the machine in forward and reverse directions. Steady state and transient results of the proposed drive are also presented for different operating conditions, through the simulation study followed by experimental verifications. Even though the simulation and experimental verifications are done on a 5-level inverter to explain the proposed hysteresis controller, it can be easily implemented for any general n-level inverter, as described in this thesis.

The popularity of distributed generating (DG) sources have been increasing over the past few years. With the increasing penetration of these DGs, the concept of micro grid is becoming popular. A micro grid is a small power system network with distributed generating sources which can operate seamlessly irrespective of the presence of the utility grid. Operating the micro grid in this manner increases system reliability and reduces power interruptions. However, it introduces several control challenges. This thesis aims at analysing the behaviour of a micro grid system during the transition between grid connected mode and islanded mode of operation and address the control challenges through novel schemes. With the presence of grid, the micro grid system variables, such as voltage and frequency, are strictly regulated by the grid. The local sources follow the voltage and frequency reference set by the grid and supply constant power. With the loss of grid, that is when the system is islanded, the network variables need to be regulated by the local sources. The control structures for the inverter-based sources during the two operating modes are detailed in the present work. With the loss of grid, the system should be able to transfer seamlessly to islanded mode without any transients. Similarly, when the grid supply is restored, the micro grid should seamlessly resynchronize to the grid without any transients. This thesis proposes two novel controller schemes for achieving seamless transfer between grid-connected and islanded mode in micro grids. The rst scheme uses an output feedback topology to reduce the transitions during mode transfer. The second scheme uses a Linear Quadratic Regulator (LQR) theory based compensator to achieve seamless transfer. The performance of the proposed schemes have been validated through simulations on a benchmark micro grid network for various operating conditions. An experimental micro grid set-up is developed with a single inverter based DG source. The droop control scheme for islanded mode of operation has been validated on hardware.

This diploma thesis is focused on development and initial run of a measurement system whose aim is to measure photovoltaic panel efficiency. Experimental photovoltaic panel is installed outside the laboratory. Measurement system consists of the solar radiation measurement module (pyranometer), photovoltaic panel load module (panel power measurement) and panel climate measurement module. Data from measurement module is being captured via control computer for subsequent analysis of panel efficiency and climatic impacts on it.