This thesis focuses on the study, implementation and improvement of a digital controller for a power factor correction (PFC) converter. The development of the telecommunications industry and the Internet demands reliable, cost-effective and intelligent power. Nowadays, the telecommunication power systems have output current of up to several kilo amperes, consisting of tens of modules. The high-end server system, which holds over 100 CPUs, consumes tens of kilowatts of power. For mission-critical applications, communication between modules and system controllers is critical for reliability. Information about temperature, current, and the total harmonic distortion (THD) of each module will enable the availability of functions such as dynamic temperature control, fault diagnosis and removal, and adaptive control, and will enhance functions such as current sharing and fault protection. The dominance of analog control at the modular level limits system-module communications. Digital control is well recognized for its communication ability. Digital control will provide the solution to system-module communication for the DC power supply. The PFC converter is an important stage for the distributed power system (DPS). Its controller is among the most complex with its three-loop structure and multiplier/divider. This thesis studies the design method, implementation and cost effectiveness of digital control for both a PFC converter and for an advanced PFC converter. Also discussed is the influence of digital delay on PFC performance. A cost-effective solution that achieves good performance is provided. The effectiveness of the solution is verified by simulation. The three level PFC with range switch is well recognized for its high efficiency. The range switch changes the circuit topology according to the input voltage level. Research literature has discussed the optimal control for both range-switch-off and range-switch-on topologies. Realizing optimal analog control requires a complex structure. Until now optimal control for the three-level PFC with analog control has not been achieved. Another disadvantage of the three-level PFC is the output capacitor voltage imbalance. This thesis proposes an active balancing solution to solve this problem. / Master of Science

Approved for public release; distribution in unlimited. / This thesis develops and implements a Control Moment Gyroscope (CMG) steering law, controller and active balancing system for a three-axis satellite simulator (TASS). The CMGs are configured in a typical pyramid configuration (the fourth CMG position being null). The development was done primarily with simulation and experiments utilizing Real Time Workshop and XPC Target of MATLAB and SIMULINK. The TASS is a double circular platform mounted on a spherical air bearing with the center of rotation (CR) about the approximate physical geometric center of the simulator. The TASS utilizes three moveable masses in the three body axes for balancing which actively eliminate any center of gravity (CG) offset and return the CG to the CR. The TASS supports an optics payload designed to acquire, track and point a received laser beam onto an off-satellite target. The target may be stationary or moving. Actively balancing the TASS reduces the torque output requirement for the CMGs while maintaining either a stabilized level platform or a particular commanded attitude. Reduction or elimination of torque output from the CMGs results in a more stabilized platform, less structural induced vibration, less jitter in payload optics and less power required in spacecraft applications. / Lieutenant Commander, United States Navy

Este trabalho se insere no contexto de redução de vibrações de rotores via mancais ativos. Essas vibrações são causadas pelo desbalanço do próprio rotor e possuem frequência igual à frequência de rotação desse rotor. O desbalanço pode ser modelado como uma força de perturbação girante, sendo que uma técnica bastante conhecida para anular o efeito dessa perturbação é o balanceamento eletrônico, também chamado de compensação síncrona de desbalanço ou de regulação sincronizada. A presente dissertação traz duas contribuições para o tema. A primeira é a simplificação do compensador síncrono através de considerações de simetria do rotor e de isotropia dos mancais, e a segunda é a obtenção do modelo exato do sistema discreto resultante da aplicação da metodologia de compensação síncrona. Tais contribuições se valem da descrição do modelo em coordenadas complexas. À transformação de coordenadas reais para coordenadas complexas deu-se o nome de complexificação. Assim sendo, a complexificação do modelo permite dividir por dois a dimensão das variáveis do sistema (estados, entradas e saídas), além de dar sentido físico à separação entre os distúrbios diretos (caso do desbalanço) e os distúrbios retrógrados. Essa complexificação reduz o tempo de identificação da matriz de influência feita no balanceamento eletrônico, e o modelo complexificado obtido através das hipóteses de simetria e isotropia permite desacoplar completamente a compensação das perturbações diretas da compensação das perturbações retrógradas. / This work is inserted in the context of active attenuation of rotor vibrations. These vibrations are caused by the rotor\'s own unbalance and have a frequency equal to the rotor\'s rotation frequency. The unbalance can be modeled as a rotating disturbance force, and a well-known technique for cancelling the effect of such a disturbance is the so-called active balancing, also known as synchronous unbalance compensation or synchronized regulation. The present dissertation brings two contributions to the theme. The first one is the simplification of the synchronous compensator through considerations of rotor symmetry and bearing isotropy, and the second one is to obtain the exact model of the discrete system resulting from the application of the synchronous compensation methodology. These contributions make use of the model described in complex coordinates. The transformation from real coordinates to complex coordinates is defined as a complexification. Thus, the complexification of the model allows the division in half of the dimension of the system variables (states, inputs and outputs), as well as giving a physical sense to the separation between forward disturbances (case of the rotor unbalance) and backward disturbances. This complexification reduces the time of identification of the influence matrix made in active balancing, and the complexified model obtained through symmetry and isotropy hypotheses allows the completely uncouple of the forward disturbances compensation from the backward disturbances compensation.

Este trabalho se insere no contexto de redução de vibrações de rotores via mancais ativos. Essas vibrações são causadas pelo desbalanço do próprio rotor e possuem frequência igual à frequência de rotação desse rotor. O desbalanço pode ser modelado como uma força de perturbação girante, sendo que uma técnica bastante conhecida para anular o efeito dessa perturbação é o balanceamento eletrônico, também chamado de compensação síncrona de desbalanço ou de regulação sincronizada. A presente dissertação traz duas contribuições para o tema. A primeira é a simplificação do compensador síncrono através de considerações de simetria do rotor e de isotropia dos mancais, e a segunda é a obtenção do modelo exato do sistema discreto resultante da aplicação da metodologia de compensação síncrona. Tais contribuições se valem da descrição do modelo em coordenadas complexas. À transformação de coordenadas reais para coordenadas complexas deu-se o nome de complexificação. Assim sendo, a complexificação do modelo permite dividir por dois a dimensão das variáveis do sistema (estados, entradas e saídas), além de dar sentido físico à separação entre os distúrbios diretos (caso do desbalanço) e os distúrbios retrógrados. Essa complexificação reduz o tempo de identificação da matriz de influência feita no balanceamento eletrônico, e o modelo complexificado obtido através das hipóteses de simetria e isotropia permite desacoplar completamente a compensação das perturbações diretas da compensação das perturbações retrógradas. / This work is inserted in the context of active attenuation of rotor vibrations. These vibrations are caused by the rotor\'s own unbalance and have a frequency equal to the rotor\'s rotation frequency. The unbalance can be modeled as a rotating disturbance force, and a well-known technique for cancelling the effect of such a disturbance is the so-called active balancing, also known as synchronous unbalance compensation or synchronized regulation. The present dissertation brings two contributions to the theme. The first one is the simplification of the synchronous compensator through considerations of rotor symmetry and bearing isotropy, and the second one is to obtain the exact model of the discrete system resulting from the application of the synchronous compensation methodology. These contributions make use of the model described in complex coordinates. The transformation from real coordinates to complex coordinates is defined as a complexification. Thus, the complexification of the model allows the division in half of the dimension of the system variables (states, inputs and outputs), as well as giving a physical sense to the separation between forward disturbances (case of the rotor unbalance) and backward disturbances. This complexification reduces the time of identification of the influence matrix made in active balancing, and the complexified model obtained through symmetry and isotropy hypotheses allows the completely uncouple of the forward disturbances compensation from the backward disturbances compensation.

L'utilisation de systèmes de stockage de l'énergie électrique tels que les batteries nécessite l'assemblage de plusieurs cellules. Comme chacune de ces dernières peut avoir des caractéristiques légèrement différentes ainsi que des conditions d'environnement thermique ou de vieillissement distinctes, l'utilisation d'un système d'équilibrage permettant une bonne gestion de la répartition de l'énergie au sein des éléments qui composent le pack est nécessaire. Les travaux de recherche présentés se rapportent à l'étude et à la conception d'un tel circuit d'équilibrage à base de convertisseurs d'énergie intégrables ainsi qu'aux sollicitations électriques engendrées dans les cellules lors de son utilisation. / To store electrical energy in batteries, the use of multiple cells is needed. Since each of these cells can have slightly different characteristics and also different thermal or aging environmental conditions, a balancing system is required to manage the energy inside the battery pack. The researches described in this document show the study and the design of such a balancing system based on power electronics converters and also the impact of these systems on the electrochemical cells.

Energy storage systems with many Lithium Ion battery cells per string require sophisticated balancing hardware due to individual cells having manufacturing inconsistencies, different self discharge rates, internal resistances and temperature variations. For capacity maximization, safe operation, and extended lifetime, battery balancing is required. Redistributive Non-Dissipative balancing further improves the pack capacity and efficiency over a Dissipative approach where energy is wasted as heat across shunt resistors. Redistribution techniques dynamically shuttle charge to and from weak cells during operation such that all of the stored energy in the stack is utilized. This thesis identifies and develops different balancing control methods. These methods include a unconstrained optimization problem using a Linear Quadratic Regulator (LQR) and a constrained optimization problem using Model Predictive Control (MPC). These methods are benchmarked against traditional rule based (RB) balancing. The control systems are developed using MATLAB/Simulink and validated experimentally on a multiple transformer individual cell to stack topology. The implementation uses a DC2100A Demo-board from Linear Technology with bi-directional flyback converters to transfer the energy between the cells. The results of this thesis show that the MPC control method has the highest balancing efficiency and minimum balancing time. / Thesis / Master of Applied Science (MASc)