Tesi sul tema "Maximum power"

Thesis (Ph. D.)--University of Florida, 2002.
Title from title page of source document. Document formatted into pages; contains vii, 175 p.; also contains graphics. Includes vita. Includes bibliographical references.

This thesis begins with providing a basic introduction of electricity requirements for small developing country communities serviced by small scale generating units (focussing mainly on small wind turbine, small Photo Voltaic system and Micro-Hydro Power Plants). Scenarios of these small scale units around the world are presented. Companies manufacturing different size wind turbines are surveyed in order to propose a design that suits the most abundantly available and affordable turbines. Different Maximum Power Point Tracking (MPPT) algorithms normally employed for these small scale generating units are listed along with their working principles. Most of these algorithms for MPPT do not require any mechanical sensors in order to sense the control parameters like wind speed and rotor speed (for small wind turbines), temperature and irradiation (for PV systems), and water flow and water head (for Micro-Hydro). Models for all three of these systems were developed in order to generate Maximum Power Point (MPP) curves. Similarly, a model for Permanent Magnet Synchronous Generators (PMSGs) has been developed in the d-q reference frame. A boost rectifier which enables active Power Factor Correction (PFC) and has a DC regulated output voltage is proposed before implementing a MPPT algorithm. The proposed boost rectifier works on the principle of Direct Power Control Space Vector Modulation (DPC-SVM) which is based on instantaneous active and reactive power control loops. In this technique, the switching states are determined according to the errors between commanded and estimated values of active and reactive powers. The PMSG and Wind Turbine behaviour are simulated at various wind speeds. Similarly, simulation of the proposed PFC boost rectifier is performed in matlab/simulink. The output of these models are observed for the variable wind speeds which identifies PFC and boosted constant DC output voltage is obtained. A buck converter that employs the MPPT algorithm is proposed and modeled. The model of a complete system that consists of a variable speed small wind turbine, PMSG, DPC-SVM boost rectifier, and buck converter implementing MPPT algorithm is developed. The proposed MPPT algorithm is based upon the principle of adjusting the duty ratio of the buck converter in order reach the MPP for different wind speeds (for small wind turbines) and different water flow rates (Micro-Hydro). Finally, a prototype DPC-SVM boost rectifier and buck converter was designed and built for a turbine with an output power ranging from 50 W-1 kW. Inductors for the boost rectifier and buck DC-DC converter were designed and built for these output power ranges. A microcontroller was programmed in order to generate three switching signals for the PFC boost rectifier and one switching signal for the MPPT buck converter. Three phase voltages and currents were sensed to determine active and reactive power. The voltage vectors were divided into 12 sectors and a switching algorithm based on the DPC-SVM boost rectifier model was implemented in order to minimize the errors between commanded and estimated values of active and reactive power. The system was designed for charging 48 V battery bank. The generator three phase voltage is boosted to a constant 80 V DC. Simulation results of the DPC-SVM based rectifier shows that the output power could be varied by varying the DC load maintaining UPF and constant boosted DC voltage. A buck DC-DC converter is proposed after the boost rectifier stage in order to charge the 48 V battery bank. Duty ratio of the buck converter is varied for varying the output power in order to reach the MPP. The controller prototype was designed and developed. A laboratory setup connecting 4 kW induction motor (behaving as a wind turbine) with 1kW PMSG was built. Speed-torque characteristic of the induction motor is initially determined. The torque out of the motor varies with the motor speed at various motor supply voltages. At a particular supply voltage, the motor torque reaches peak power at a certain turbine speed. Hence, the control algorithm is tested to reach this power point. Although the prototype of the entire system was built, complete results were not obtained due to various time constraints. Results from the boost rectifier showed that the appropriate switching were performed according to the digitized signals of the active and reactive power errors for different voltage sectors. Simulation results showed that for various wind speed, a constant DC voltage of 80 V DC is achieved along with UPF. MPPT control algorithm was tested for induction motor and PMSG combination. Results showed that the MPPT could be achieved by varying the buck converter duty ratio with UPF achieved at various wind speeds.

In recent years, wind energy technology has become one of the top areas of interest for energy harvesting in the power electronics world. This interest has especially peaked recently due to the increasing demand for a reliable source of renewable energy. In a recent study, the American Wind Energy Association (AWEA) ranked the U.S as the leading competitor in wind energy harvesting followed by Germany and Spain. Although the United States is the leading competitor in this area, no one has been able successfully develop an efficient, low-cost AC/DC convertor for low power turbines to be used by the average American consumer. There has been very little research in low power AC/DC converters for low to medium power wind energy turbines for battery charging applications. Due to the low power coefficient of wind turbines, power converters are required to transfer the maximum available power at the highest efficiency. Power factor correction (PFC) and maximum power point tracking (MPPT) algorithms have been proposed for high power wind turbines. These turbines are out of the price range of what a common household can afford. They also occupy a large amount of space, which is not practical for use in one's home. A low cost AC/DC converter with efficient power transfer is needed in order to promote the use of cheaper low power wind turbines. Only MPPT is implemented in most of these low power wind turbine power converters. The concept of power factor correction with MPPT has not been completely adapted just yet. The research conducted involved analyzing the effect of power factor correction and maximum power point tracking algorithm in AC/DC converters for wind turbine applications. Although maximum power to the load is always desired, most converters only take electrical efficiency into consideration. However, not only the electrical efficiency must be considered, but the mechanical energy as well. If the converter is designed to look like a purely resistive load and not a switched load, a wind turbine is able to supply the maximum power with lower conduction loss at the input side due to high current spikes. Two power converters, VIENNA with buck converter and a Buck-boost converter, were designed and experimentally analyzed. A unique approach of controlling the MPPT algorithm through a conductance G for PFC is proposed and applied in the VIENNA topology. On the other hand, the Buck-boost only operates MPPT. With the same wind profile applied for both converters, an increase in power drawn from the input increased when PFC was used even when the power level was low. Both topologies present their own unique advantages. The main advantage for the VIENNA converter is that PFC allowed more power extraction from the turbine, increasing both electrical and mechanical efficiency. The buck-boost converter, on the other hand, presents a very low component count which decreases the overall cost and volume. Therefore, a small, cost-effective converter that maximizes the power transfer from a small power wind turbine to a DC load, can motivate consumers to utilize the power available from the wind.
M.S.E.E.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering MSEE

The purpose of this work is to develop a maximum power tracking control strategy for variable speed wind turbine systems. Modern wind turbine control systems are slow, and they depend on the design parameters of the turbine and use wind and/or rotor speed measurements as control variable inputs. The dependence on the accuracy of the measurement devices makes the controller less reliable. The proposed control scheme is based on the stiff system concept and provides a fast response and a dynamic solution to the complicated aerodynamic system. This control scheme provides a response to the wind changes without the knowledge of wind speed and turbine parameters. The system consists of a permanent magnet synchronous machine (PMSM), a passive rectifier, a dc/dc boost converter, a current controlled voltage source inverter, and a microcontroller that commands the dc/dc converter to control the generator for maximum power extraction. The microcontroller will also be able to control the current output of the three-phase inverter. In this work, the aerodynamic characteristics of wind turbines and the power conversion system topology are explained. The maximum power tracking control algorithm with a variable step estimator is introduced and the modeling and simulation of the wind turbine generator system using the MATLAB/SIMULINK® software is presented and its results show, at least in principle, that the maximum power tracking algorithm developed is suitable for wind turbine generation systems.

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.
Includes bibliographical references (p. 79-80).
This thesis describes the design, and validation of a maximum power point tracking DC-DC converter capable of following the true global maximum power point in the presence of other local maximum. It does this without the use of costly components such as analog-to-digital converters and microprocessors. It substantially increases the efficiency of solar power conversion by allowing solar cells to operate at their ideal operating point regardless of changes in load, and illumination. The converter switches between a dithering algorithm which tracks the local maximum and a global search algorithm for ensuring that the converter is operating at the true global maximum.
by Joseph Duncan.
M.Eng.

This thesis presents an optimal method of designing and controlling an oscillating energy harvesting system. Many new and emerging energy harvesting systems, such as the energy harvesting backpack and ocean wave energy harvesting, capture energy normally expelled through mechanical interactions. Often the nature of the system indicates slow system time constants and unsteady AC voltages. This paper reveals a method for achieving maximum energy harvesting from such sources with fast determination of the optimal operating condition. An energy harvesting backpack, which captures energy from the interaction between the user and the spring decoupled load, is presented in this paper. The new control strategy, maximum energy harvesting control (MEHC), is developed and applied to the energy harvesting backpack system to evaluate the improvement of the MEHC over the basic maximum power point tracking algorithm.
M.S.E.E.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering MSEE

An investigation into the design of a stand-alone photovoltaic water pumping system for supplying rural areas is presented. It includes a study of system components and their modelling. The PV water pumping system comprises a solar-cell-array, DC-DC buck chopper and permanent-magnet DC motor driving a centrifugal pump. The thesis focuses on increasing energy extraction by improving maximum power point tracking (MPPT). From different MPPT techniques previously proposed, the perturb and observe (P&O) technique is developed because of its ease of implementation and low implementation cost. A modified variable step-size P&O MPPT algorithm is investigated which uses fuzzy logic to automatically adjust step-size to better track maximum power point. Two other MPPT methods are investigated: a new artificial neural network (ANN) method and fuzzy logic (FL) based method. These use PV source output power and the speed of the DC pump motor as input variables. Both generate pulse width modulation (PWM) control signals to continually adjust the buck converter to maximize power from the PV array, and thus motor speed and the water discharge rate of a centrifugal pump. System elements are individually modelled in MATLAB/SIMULINK and then connected to assess performance under different PV irradiation levels. First, the MP&O MPPT technique is compared with the conventional P&O MPPT algorithm. The results show that the MP&O MPPT has faster dynamic response and eliminates oscillations around the MPP under steady-state conditions. The three proposed MPPT methods are implemented in the simulated PV water pumping system and compared. The results confirm that the new methods have improved energy extraction and dynamic tracking compared with simpler methods.

The SIUe solar car team lacks a competitive communication system. To enable the competitive edge a major upgrade to the electronics and wiring was required. A new maximum power point tracker and driver support system was developed to give them the competitive edge.

This thesis proposes a new maximum power point tracking (MPPT) method for photovoltaic (PV) systems using Kalman filter. The Perturbation & Observation (P&O) method is widely used due to its easy implementation and simplicity. The P&O usually requires a dithering scheme to reduce noise effects, but the dithering scheme slows the tracking response time. Tracking speed is the most important factor for improving efficiency under frequent environmental change. The proposed method is based on the Kalman filter. An adaptive MPPT algorithm which uses an instantaneous power slope has introduced, but process and sensor noises disturb its estimations. Thus, applying the Kalman filter to the adaptive algorithm is able to reduce tracking failures by the noises. It also keeps fast tracking performance of the adaptive algorithm, so that enables using the Kalman filter to generate more powers under rapid weather changes than using the P&O. For simulations, a PV system is introduced with a 30kW array and MPPT controller designs using the Kalman filter and P&O. Simulation results are provided the comparison of the proposed method and the P&O on transient response for sudden system restart and irradiation changes in different noise levels. The simulations are also performed using real irradiance data for two entire days, one day is smooth irradiance changes and the other day is severe irradiance changes. The proposed method has showed the better performance when the irradiance is severely fluctuating than the P&O while the two methods have showed the similar performances on the smooth irradiance changes.
Master of Science

The increase in demand for renewable energy sources has been exponential in recent years and is mainly driven by factors that include the growth of greenhouse emissions and the decline in fossil fuel reservoirs. Photovoltaic (PV) energy, one of the more prominent renewable energy sources, produces electricity directly from sunlight, noiselessly and harmlessly to the environment. Additionally, PV energy systems are easy to install and financially supported by many governments, which has helped disseminate PV technology worldwide. The total generated power from PV installations (and the number of installations) has increased more than two-fold during the past 3 years, so that now more than 177 GW of PV-generated power is delivered per year. Researchers have been led to work on the obstacles facing PV systems from different perspectives, including: installation cost, inconsistency, and conversion and interface efficiency. The aim of this thesis is to design a high-efficiency PV inverter system configuration. The contribution to the knowledge in this thesis can be divided into two parts. The first part contains a critical analysis of different maximum power point tracking (MPPT) techniques. The second part provides a detailed design of the inverter system, which consists of a boost converter and a low-frequency H-bridge. Together, the three parts in this contribution present a complete high efficiency PV inverter system. The proposed system maintains high-efficiency energy delivery by reducing the number of high-frequency switches, which waste a significant amount of energy and reduce system efficiency. In order to show the superiority of the proposed configuration, a power loss analysis comparison with the other existing configurations is presented. In addition, different scenarios have been simulated with Matlab/Simulink. The results of these simulations confirm the distinction of the proposed configuration as well as its low-loss, high-efficiency characteristics which is rated at 98.8%.

In this thesis, a maximum power point tracking (MPPT) for multiple input single output (MISO) converter is presented such that power generated from multiple individual energy sources can be combined to deliver the maximum amount of power to a common resistive load. Typically, MISO converters will employ techniques that yield equal current sharing from each energy source. However, this may not be desirable since each source may be rated at different power ratings and/or may experience different operating conditions, preventing the system MISO converter to acquire the most available total power from the sources. Utilizing MPPT control would therefore be beneficial in maximizing the output power of the MISO converter system. In this thesis, a proposed two-stage converter system is presented to incorporate the MPPT control in the MISO system. The initial stage implements the MPPT, drawing as much power from the corresponding source. The second stage regulates the output voltage of the MPPT. To evaluate the performance and efficiency of the proposed system, simulation with two solar panels as the sources was performed using Simulink with various test cases to fully explore the viability of the system. Simulation results were also used to compare with those obtained from a system without the MPPT. Results show that the proposed system with the MPPT stage is able to improve input regulation and increase the total amount of power acquired from the sources compared to the system without the MPPT. Further testing with hardware setup confirms the simulation results and demonstrates that even with large differences in input powers, the most total amount of power is achieved and utilized.

It is essential to always track maximum power from photovoltaic (PV) sources. Failure to track the global maximum power point under partial shading conditions is one of the major reasons that lead to significant power losses. Several maximum power point tracking methods have been proposed to deal with this problem. However, none of them were able to effectively identify the occurrence of partial shading. With the facility of Matlab modelling and simulation as well as the aid of a constructed solar emulator, the power-voltage characteristics of a PV panel under uniform and non-uniform irradiance conditions have been studied and some useful conclusions have been identified from observation. Based on these conclusions, a novel maximum power point tracking algorithm has been proposed, which is capable of identifying the occurrence of partial shading hence determining the need for a global scan over the operation range of PV panels for the true maximum power point. In the meantime, the effect of PV dynamics, due to the capacitance of PV cells, on maximum power point trackers has been investigated and some initial results and suggestions have been presented in this work.

La creixent demanda energètica, l’esgotament dels combustibles fòssils i l’augment de l’escalfament global a causa de l’emissió de carboni ha donat lloc a la necessitat d’un sistema energètic alternatiu, global i respectuós amb el medi ambient. L’energia solar es considera una de les formes d’energia més inesgotables d’aquest univers, però té el problema de la baixa eficiència a causa de les diferents condicions ambientals. El panell solar presenta un comportament no lineal en condicions climàtiques reals i la potència de sortida fluctua amb la variació de la irradiació solar i la temperatura. El canvi de les condicions meteorològiques i el comportament no lineal dels sistemes fotovoltaics suposen un repte en el seguiment de diferents PowerPoint màxims. Per tant, per extreure i lliurar contínuament la màxima potència possible del sistema fotovoltaic, en determinades condicions ambientals, s’ha de formular l’estratègia de control de seguiment del punt de potència màxima (MPPT) que funcioni contínuament el sistema fotovoltaic al seu MPP. Es necessita un controlador no lineal robust per garantir el MPPT mitjançant la manipulació de les línies no lineals d’un sistema i el fa robust contra les condicions ambientals canviants. El control de mode lliscant (SMC) s’utilitza àmpliament en sistemes de control no lineals i s’ha implementat en sistemes fotovoltaics (PVC) per rastrejar MPP. SMC és robust contra les pertorbacions, les incerteses del model i les variacions paramètriques. Representa fenòmens indesitjables com el xerramec, inherent al fet que provoca pèrdues d’energia i calor. En aquesta tesi, en primer lloc, es formula un controlador SMC d’ordre sencer per extreure la màxima potència d’un sistema solar fotovoltaic en condicions climàtiques variables que utilitzen l’esquema MPPT de pertorbació i observació (P \ & O) del sistema fotovoltaic autònom proposat. El sistema proposat consta de dos esquemes de bucles, a saber, el bucle de cerca i el bucle de seguiment. P&O MPPT s’utilitza al bucle de cerca per generar el senyal de referència i un controlador SMC de seguiment s’utilitza a l’altre bucle per extreure la màxima potència fotovoltaica. El sistema fotovoltaic es connecta amb la càrrega mitjançant el convertidor d’alimentació electrònic DC-DC de potència. Primer es deriva un model matemàtic del convertidor d’augment i, basat en el model derivat, es formula un SMC per controlar els impulsos de la porta del commutador del convertidor d’augment. L’estabilitat del sistema de bucle tancat es verifica mitjançant el teorema d’estabilitat de Lyapunov. L’esquema de control proposat es prova amb diferents nivells d’irradiació i els resultats de la simulació es comparen amb el controlador de derivades integrals proporcionals clàssiques (PID). El SMC clàssic representa fenòmens indesitjables com el xerramec, inherent al fet que provoca pèrdues d’energia i calor. A la següent part d’aquesta tesi, es discuteix el disseny del controlador de mode lliscant adaptatiu (ASMC) per al sistema fotovoltaic proposat. El control adoptat s’executa mitjançant un ASMC i la millora s’actualitza mitjançant un algorisme d’optimització MPPT de mètode de cerca de patrons millorats (IPSM). S’utilitza un MPPT IPSM per generar la tensió de referència per tal de comandar el controlador ASMC subjacent. S’ha dut a terme una comparació amb altres dos algoritmes d’optimització, a saber, Perturb \ & Observe (P&O) i Particle Swarm Optimization (PSO) amb IPSM per MPPT. Com a estratègia no lineal, l’estabilitat del controlador adaptatiu es garanteix mitjançant la realització d’una anàlisi de Lyapunov. El rendiment de les arquitectures de control proposades es valida comparant les propostes amb la del conegut i àmpliament utilitzat controlador PID.
La creciente demanda de energía, el agotamiento de los combustibles fósiles y el aumento del calentamiento global debido a la emisión de carbono han hecho surgir la necesidad de un sistema energético alternativo, de eficiencia general y respetuoso con el medio ambiente. La energía solar se considera una de las formas de energía más inagotables de este universo, pero tiene el problema de la baja eficiencia debido a las diferentes condiciones ambientales. El panel solar exhibe un comportamiento no lineal en condiciones climáticas reales y la potencia de salida fluctúa con la variación de la irradiancia solar y la temperatura. Las condiciones climáticas cambiantes y el comportamiento no lineal de los sistemas fotovoltaicos plantean un desafío en el seguimiento de la variación máxima de PowerPoint. Por lo tanto, para extraer y entregar continuamente la máxima potencia posible del sistema fotovoltaico, en determinadas condiciones ambientales, se debe formular la estrategia de control de seguimiento del punto de máxima potencia (MPPT) que opere continuamente el sistema fotovoltaico en su MPP. Se requiere un controlador no lineal robusto para asegurar MPPT manejando las no linealidades de un sistema y haciéndolo robusto frente a condiciones ambientales cambiantes. El control de modo deslizante (SMC) se usa ampliamente en sistemas de control no lineales y se ha implementado en sistemas fotovoltaicos (PVC) para rastrear MPP. SMC es robusto contra perturbaciones, incertidumbres del modelo y variaciones paramétricas. Representa fenómenos indeseables como el parloteo, inherentes a él, que provocan pérdidas de energía y calor. En esta tesis, en primer lugar, se formula un controlador SMC de orden entero para extraer la máxima potencia de un sistema fotovoltaico solar en condiciones climáticas variables empleando el esquema MPPT de perturbar y observar (P&O) para el sistema fotovoltaico autónomo propuesto. El sistema propuesto consta de dos esquemas de bucles, a saber, el bucle de búsqueda y el bucle de seguimiento. P&O MPPT se utiliza en el bucle de búsqueda para generar la señal de referencia y se utiliza un controlador SMC de seguimiento en el otro bucle para extraer la máxima potencia fotovoltaica. El sistema fotovoltaico está conectado con la carga a través del convertidor elevador DC-DC electrónico de potencia. Primero se deriva un modelo matemático del convertidor elevador y, en base al modelo derivado, se formula un SMC para controlar los pulsos de puerta del interruptor del convertidor elevador. La estabilidad del sistema de circuito cerrado se verifica mediante el teorema de estabilidad de Lyapunov. El esquema de control propuesto se prueba bajo diferentes niveles de irradiancia y los resultados de la simulación se comparan con el controlador clásico proporcional integral derivado (PID). El SMC clásico describe fenómenos indeseables como el parloteo, inherente a él, que causa pérdidas de energía y calor. En la siguiente parte de esta tesis, se analiza el diseño del controlador de modo deslizante adaptativo (ASMC) para el sistema fotovoltaico propuesto. El control adoptado se ejecuta utilizando un ASMC y la mejora se actualiza utilizando un algoritmo de optimización MPPT del Método de búsqueda de patrón mejorado (IPSM). Se utiliza un IPSM MPPT para generar el voltaje de referencia para controlar el controlador ASMC subyacente. Se ha realizado una comparación con otros dos algoritmos de optimización, a saber, Perturb \ Observe (P&O) y Particle Swarm Optimization (PSO) con IPSM para MPPT. Como estrategia no lineal, la estabilidad del controlador adaptativo está garantizada mediante la realización de un análisis de Lyapunov.
The increasing energy demands, depleting fossil fuels, and increasing global warming due to carbon emission has arisen the need for an alternate, overall efficiency, and environment-friendly energy system. Solar energy is considered to be one of the most inexhaustible forms of energy in this universe, but it has the problem of low efficiency due to varying environmental conditions. Solar panel exhibits nonlinear behavior under real climatic conditions and output power fluctuates with the variation in solar irradiance and temperature. Changing weather conditions and nonlinear behavior of PV systems pose a challenge in the tracking of varying maximum PowerPoint. Hence, to continuously extract and deliver the maximum possible power from the PV system, under given environmental conditions, the maximum power point tracking (MPPT) control strategy needs to be formulated that continuously operates the PV system at its MPP. A robust nonlinear controller is required to ensure MPPT by handling nonlinearities of a system and making it robust against changing environmental conditions. Sliding mode control (SMC) is extensively used in non-linear control systems and has been implemented in photovoltaic systems (PV) to track MPP. SMC is robust against disturbances, model uncertainties, and parametric variations. It depicts undesirable phenomena like chattering, inherent in it causing power and heat losses. In this thesis, first, an integer order SMC controller is formulated for extracting maximum power from a solar PV system under variable climatic conditions employing the perturb and observe (P&O) MPPT scheme for the proposed stand-alone PV system. The proposed system consists of two loops schemes, namely the searching loop and the tracking loop. P&O MPPT is utilized in the searching loop to generate the reference signal and a tracking SMC controller is utilized in the other loop to extract the maximum PV power. PV system is connected with load through the power electronic DC-DC boost converter. A mathematical model of the boost converter is derived first, and based on the derived model, an SMC is formulated to control the gate pulses of the boost converter switch. The closed-loop system stability is verified through the Lyapunov stability theorem. The proposed control scheme is tested under varying irradiance levels and the simulation results are compared with the classical proportional integral derivative (PID) controller. Classical SMC depicts undesirable phenomena like chattering, inherent in it causing power and heat losses. In the next part of this thesis, the design of the adaptive sliding mode controller (ASMC) is discussed for the proposed PV system. The adopted control is executed utilizing an ASMC and the enhancement is actualized utilizing an Improved Pattern Search Method (IPSM) MPPT optimization algorithm. An IPSM MPPT is used to generate the reference voltage in order to command the underlying ASMC controller. Comparison with two other optimization algorithms, namely, a Perturb & Observe (P&O) and Particle Swarm Optimization (PSO) with IPSM for MPPT has been conducted. As a non-linear strategy, the stability of the adaptive controller is guaranteed by conducting a Lyapunov analysis. The performance of the proposed control architectures is validated by comparing the proposals with that of the well-known and widely used PID controller. The simulation results validate that the proposed controller effectively improves the voltage tracking, system power with reduced chattering effect, and steady-state error. A tabular comparison is provided at the end of each optimization algorithm category as a resume quantitative comparison. It is anticipated that this work will serve as a reference and provides important insight into MPPT control of the PV systems.

Maximum Power Point Tracking (MPPT) strategies in Photovoltaic (PV) systems ensure efficient utilization of PV arrays. Among different strategies, the Perturb and Observe (P&O) algorithm has gained wide popularity due to its intuitive nature and simple implementation. However, such simplicity in P&O introduces two inherent issues, an artificial perturbation that creates losses in steady-state operation and a limited ability to track transients in changing environmental conditions. This work develops and discusses in detail an MPPT algorithm with zero oscillation and slope tracking to address those technical challenges. The strategy combines three techniques to improve steady-state behavior and transient operation: 1) idle operation on the Maximum Power Point (MPP), 2) identification of the irradiance change through a natural perturbation and 3) a simple multi-level adaptive tracking step. Two key elements, which form the foundation of the proposed solution, are investigated: the suppression of the artificial perturbation at the MPP and the indirect identification of irradiance change through a current-monitoring algorithm which acts as a natural perturbation. The Zero-oscillation, Adaptive step Perturb and Observe (ZA-P&O) MPPT strategy builds on these mechanisms to identify relevant information and produce efficiency gains. As a result, the combined techniques achieve superior overall performance while maintaining simplicity of implementation. Simulations and experimental results are provided to validate the proposed strategy and illustrate its behavior in steady state and transient operation.
Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate

In grid connected photovoltaic (PV) generation systems, inverters are used to convert the generated DC voltage to an AC voltage. An additional dc-dc converter is usually connected between the PV source and the inverter for Maximum Power Point Tracking (MPPT). An iterative MPPT algorithm searches for the optimum operating point of PV cells to maximise the output power under various atmospheric conditions. It is desirable to be able to represent the dynamics of the changing PV power yield within stability studies of the AC network. Unfortunately MPPT algorithms tend to be nonlinear and/or time-varying and cannot be easily combined with linear models of other system elements. In this work a new MPPT technique is developed in order to enable linear analysis of the PV system over reasonable time scales. The new MPPT method is based on interpolation and an emulated-load control technique. Numerical analysis and simulations are employed to develop and refine the MPPT. The small-signal modelling of the MPPT technique exploits the fact that the emulated-load control technique can be linearised and that short periods of interpolation can be neglected. A small-signal PV system model for variable irradiation conditions was developed. The PV system includes a PV module, a dc-dc boost converter, the proposed controller and a variety of possible loads. The new model was verified by component-level time-domain simulations. Be cause measured signals in PV systems contain noise, it is important to assess the impact of that noise on the MPPT and design an algorithm that operates effectively in pr esence of noise. For performance assessment of the new MPPT techniques, the efficiencies of various MPPT techniques in presence of noise were compared. This comparison showed superiority of the interpolation MPPT and led to conclusions about effective use of existing MPPT methods. The new MPPT method was also experimentally tested.

John L. Wyatt, Jr.
Bibliography: p. 12-13.
Supported in part by the National Science Foundation ECS-83-10941 Supported in part by the Defense Advanced Research Projects Agency under contract no. N00014-80-C-0622

碩士
聖約翰科技大學
電機工程系碩士在職專班
104
This thesis presents a novel maximum power point tracking technique for photovoltaic. The proposed technique adjusts the operating point of a photovoltaic panel based on three physical characteristics of the photovoltaic panel: (a) the incremental surface temperature is positive correlation with the variation of sunlight intensity; (b) the normalized incremental voltage is greater than the normalized incremental current at the left-hand side of the maximum power point; and (c) the normalized incremental current is greater than the normalized incremental voltage at the right-hand side of the maximum power point. The proposed technique can correctly determine the operating point of a photovoltaic panel in rapidly changed irradiation, to improve the misjudgment defect of traditional techniques. The proposed technique enables photovoltaic panels can work close to the maximum power point under different sunlight intensity, to increase the electricity generation and efficiency of photovoltaic panels.

碩士
國立臺灣大學
應用力學研究所
97
Energy development is one of the most important researches in every country. In text, we use maximum power point tracking technique in thermoelectric generator（TEG）. In text we will introduce the basic principles of thermoelectric material, maximum power transfer, single-chip control and DC-DC converter. DC-DC converter has a switch. The switch made by the semiconductor and use of pulse width modulation control for the switch. We use single-chip control to control duty cycle of pulse width modulation. The incremental conductance algorithm is one of the maximum power point tracking manner. In text we use incremental conductance algorithm to achieve maximum power point tracking. The maximum power point tracking to make the output voltage can effectively enhance and improve the use of thermoelectric generator.

Solar photovoltaic (PV) systems are distributed energy sources that are an environmentally friendly and renewable source of energy. However, solar PV power fluctuates due to variations in radiation and temperature levels. Furthermore, when the solar panel is directly connected to the load, the power that is delivered is not optimal. A maximum peak power point tracker is therefore necessary for maximum efficiency. A complete PV system equipped maximum power point tracking (MPPT) system includes a solar panel, MPPT algorithm, and a DC-DC converter topology. Each subsystem is modeled and simulated in a Matlab/Simulink environment; then the whole PV system is combined with the battery load to assess the overall performance when subjected to varying weather conditions. A PV panel model of moderate complexity based on the Shockley diode equation is used to predict the electrical characteristics of the cell with regard to changes in the atmospheric parameter of irradiance and temperature. In this dissertation, five MPPT algorithms are written in Matlab m-files and investigated via simulations. The standard Perturb and Observe (PO) algorithm along with its two improved versions and the conventional Incremental Conductance (IC) algorithm, also with its two-stage improved version, are assessed under different atmospheric operating conditions. An efficient two-mode MPPT algorithm combining the incremental conductance and the modified constant voltage methods is selected from the five ones as the best model, because it provides the highest tracking efficiencies in both sunny and cloudy weather conditions when compared to other MPPT algorithms. A DC-DC converter topology and interface study between the panel and the battery load is performed. This includes the steady state and dynamic analysis of buck and boost converters and allows the researcher to choose the appropriate chopper for the current PV system. Frequency responses using the state space averaged model are obtained for both converters. They are displayed with the help of Bode and root locus methods based on their respective transfer functions. Following the simulated results displayed in Matlab environment for both choppers, an appropriate converter is selected and implemented in the present PV system. The chosen chopper is then modeled using the Simulink Power Systems toolbox and validates the design specifications. The simulated results of the complete PV system show that the performances of the PV panel using the improved two-stage MPPT algorithm provides better steady state and fast transient characteristics when compared with the conventional incremental conductance method. It yields not only a reduction in convergence time to track the maximum power point MPP, but also a significant reduction in power fluctuations around the MPP when subjected to slow and rapid solar irradiance changes.
Thesis (M.Sc.Eng)-University of KwaZulu-Natal, Durban, 2011.

碩士
國立彰化師範大學
電機工程學系
98
This paper proposed a high- power- factor wind energy maximum power point tracking system, which is composed of three “Single Phase Power-Controlled Power Factor Correctors(PFC)” and one “Maximum Power Point Tracking Controller(MPPTC)”. With PFC and MPPTC, the proposed system can increase the power factor in the circuit and obtain the maximum energy from the three-phase wind generator. Each “Single Phase Power-Controlled Power Factor Correctors” is composed of one single-phase rectifier, one full bridge converter, and one power factor corrector (PFC) IC UC3854; and “Maximum Power Point Tracking Controller” is implemented by one microchip “HT46R24” with maximum power point tracking (MPPT) algorithm. The proposed system has advantages that modulizes the system、increases the wind generator efficiency and decreases the noise of the wind generator. At last, the proposed system will be verified by implementation of a 600W prototype As experiment results, the proposed “high- power- factor wind energy maximum power point tracking system” not only reach a high power factor at 0.98, but also operate at the mpp under different wind velocity conditions, which improves the efficiency of the wind energy system effectively.

碩士
國立成功大學
電機工程學系
102
In recent years, permanent magnetic synchronous generator (PMSG) has been widely used in the wind power generation. A PMSG needs full-rated power converter to convert wind energy into electrical energy. Due to the increasing trend of power rating on the power converter; the power converter, however, usually operates at low wind speed. Paralleling PWM rectifiers to replace a full-rated power converter can reduce current stress of the converter and improve converter’s efficiency at low wind speed. However, paralleling PWM rectifiers may cause circulating current and distort the current waveform. In order to suppress circulating current, this thesis derives three phase rectifier model which includes generator, zero sequence impedance, and design a current controller accordingly. In addition, this research adopts a novel adaptive maximum power point tracking algorithm with current distribution strategy for the paralleling PWM rectifier. In contrast to traditional perturb and observe method, novel adaptive MPPT algorithm can be easily analyzed and determine wind change by feedback signal. The effectiveness of the circulating current suppression and maximum power tracking efficiency are verified by a wind turbine emulator.

碩士
大同大學
電機工程學系(所)
97
The purpose of this thesis is to research the maximum wind power tracker. The tracker can rapidly track the maximum wind power point. A generator direct connected with wind turbine coaxial rotating transforms mechanical energy into electric energy. This tracking rule calculates wind generator output power for judging the operation point whether near the maximum power point or not. When operation point is distant from the maximum power point, the tracker adopts slope-comparing method having high tracking speed to approach maximum power point. When operation point is close to the maximum power point, the tracker adopts three-point-weighting method keeping operation point near the maximum power point. The proposed tracker can reduce tracking time and keep operation stable. In order to prove this maximum power tracker, the coreless disc permanent-magnet of generator for wind generator is implemented in this thesis. Because of non-core structure, this generator has high efficiency and high power to weight ratio. Finally, a hardware scheme consisting of single-chip microprocessor, PIC18F4520, is used in this system, and an experimental hardware scheme with software algorithm is established to prove the proposed principle in expectation to attain the maximum power tracking.

碩士
國立高雄應用科技大學
電機工程系碩士班
95
The fossil fuels have been widely used to due the fast development of the industry, and it results in the problem of the exhaustion of fossil fuels and the damage of environment. The development of renewable energy sources will be the trend from the viewpoints of protecting environment and obtaining more energy sources. Wind power is one of the important renewable energy sources. If the wind energy can be used widely and effectively, the problems of energy demand, environment pollution and greenhouse effect can be relieved. Power converter interface is one of the key technologies for the wind power generator system, and the maximum power point tracking is one of the key technologies for power converter interface of the wind power generator system. In this thesis, a maximum power point tracking method for the permanent magnet synchronous wind power generator is proposed. A prototype is developed and tested to verify the performance of the proposed maximum power point tracking method. The experimental results show that the performance of proposed method can effectively track the maximum power of the permanent magnet synchronous wind power generator.

碩士
國立中正大學
電機工程研究所
107
This thesis applies the taguchi fractional order particle swarm optimization (TFPSO) with a 2kW series buck-boost converter and TI control circuit, which is self-developed and has functions of buck and boost, as the maximum power tracker (MPPT) of the solar photovoltaic system combine with solar power prediction. No matter under ideal environmental conditions or partial shading condition(PSC), the converter can operate at maximum power point. We train parameters to be the best for MPPT on computer simulation by using Taguchi method. To verify its performance, we conducted experiment base on single- peak power curve, double-peak power curve, triple-peak power curve, quadruple-peak power curve, insolation variations, and temperature variations. Results show that the proposed TFPSO has better performance then FPSO. Considering that 2kW polycrystalline solar photovoltaic panels are prone to aging problems, Therefore, the use of convolutional neural networks (CNN) for solar power prediction, and Compare and analyze the ideal power and predicted power. Keywords：Taguchi fractional order particle swarm optimization, CNN, MPPT

碩士
國立中正大學
電機工程所
96
The main objective of this thesis is to design and implement a modular maximum power point tracker (MPPT). Due to each MPPT module only supplying partial load current, the current stress of switching components can be reduced relatively. In addition, when one of modules fails, the rest of modules can still continuously supply load current to keep the system normally operated. Each MPPT module mainly contains two parts, the MPPT control circuit and the master-slave control circuit. The MPPT control circuit uses "Perturb and Observe" technique to track the maximum power point of the solar cell array. The master-slave control circuit detects the magnitude of currents flowing through modules. The module which has the highest current would be assigned as the master module, performing MPPT control. The other slave modules adjust the current flow through themselves to achieve current distribution between each module. Simulated results and experimental results will be presented to verify the validity of the proposed circuit.

碩士
中原大學
電機工程研究所
99
This report analyzes the differences of maximum power point tracking (MPPT) methods by using MATLAB simulations. Considering the small wind power system composed of a small wind turbine, permanent-magnet synchronous generator, three-phase full bridge rectifier, DC/DC converter, MPPT power controller, and load, we will find the problems for using traditional MPPT methods. Here the fuzzy logic control method as well as perturbation and observation method is utilized for the MPPT control under several cases with step, fixed, and variable speed wind. By the MATLAB simulation tests, the fuzzy logic control MPPT method is better than the perturbation and observation method.

博士
淡江大學
電機工程學系博士班
94
The electric power supplied by a photovoltaic power generation system depends on the solar radiation and temperature. Designing efficient PV systems heavily emphasizes to track the maximum power operating point. This work develops a novel three-point weight comparison method that avoids the oscillation problem of the perturbation and observation algorithm which is often employed to track the maximum power point. Furthermore, this study proposes the series connected boost unit integrated with the proposed maximum power point tracking algorithm to improve the efficiency of the solar system. Finally, this work implements a low cost control unit on a single chip based on the proposed method to adjust the output voltage of the solar cell array. Finally, experimental results confirm the performance of the proposed method.

碩士
中原大學
電機工程研究所
105
This thesis presents a power-slope-added incremental-conductance maximum power point tracking method (PS-INC MPPT) and the control method is realized by a photovoltaic buck converter. The PS-INC MPPT is carried out in two phases: incremental-conductance tracking (INC-tracking) is performed along with the I-V curve only in the INC zone; and the power-slope tracking (PS-tracking) is carried out on the PV curve to target the INC zone. The use of PS-INC MPPT method can eliminate the ambiguous incremental-conductance detection over the I-V curve of the left-hand side of the maximum power point (MPP), allowing the maximum power tracing to proceed smoothly. This technique retains the advantage of incremental-conductance tracking in the INC zone so that the MPP tracking can be achieved accurately and quickly. Finally, a 10 kW photovoltaic buck converter is demonstrated to realize the PS-INC MPPT method. Experimental results show that both the PS-tracking and the INC tracking are quick and accurate to meet the expected tracking theme.

碩士
龍華科技大學
電機工程研究所
98
The main power of a photovoltaic power system is solar cells, so the work efficiency of solar cells is important. In order to let photovoltaic power systems output maximum power under different sunlight luminance, so we need to develop a maximum power tracker. This paper uses the digital signal controller as the core, cooperates with the appropriate peripheral hardware and maximum power point tracking technique to create maximum power tracker. To verify whether the maximum power tracker can function well in different environments, we research a set of development of verification platform for maximum power tracker for photovoltaic power systems. By simulation and experimental results we can verify that the verification systems can function well for maximum power tracker in different environments.

碩士
國立中山大學
電機工程學系研究所
106
This thesis proposes a maximum power point tracking (MPPT) scheme with bidirectional partial power regulation for a solar power system with a number of photovoltaic (PV) panels connected in series. To operate all PV panels at their maximum power points (MPPs), each panel is attached by a bidirectional flyback converter to add or subtract an adequate current to the PV current to flow into an identical series current. As a result, only a part of power is processed by the associated converters, most power is directly supplied to the load from the series PV panels. With such a configuration, none of the PV panels will be short-circuited, and hence no drastic change will happen on the output voltage, even though they are under extensively different irradiances. The system maximum power can be realized by allocating the identical series current at a specific MPP, at which, the associated flyback converters need not be activated, and at the same time the total processed power via the flyback converters can be minimized. A laboratory system composed of three PV panels with the associated bidirectional flyback converters is set up. Experimental results have demonstrated the feasibility and effectiveness of the proposed MPPT scheme under various partially shaded cases.

碩士
國立中央大學
電機工程學系
107
This thesis mainly establishes a high-efficiency solar power conversion system, and cooperates with maximum power point tracking control and DC/DC boost converter with soft switching characteristics to improve the efficiency of the overall solar power generation system. The system proposed in this thesis is mainly divided into two parts. The first part is the discussion of the maximum power point tracking strategies. It analyzes the characteristics, advantages and disadvantages of various maximum power point tracking technologies. The second part is an investigation of DC/DC boost converter with soft switching characteristics to achieve maximum power point tracking and improve the input solar source to the voltage value required at the DC bus. Using zero-voltage switching technology, the voltage of the main circuit switch is first reduced to zero and then turned on to minimize the switching loss through the second auxiliary switch and the resonant circuit. The operation time of the second auxiliary switch is determined by the algorithm in the single chip to determine the best switching time. The soft-switching technology minimizes its switching loss, and combing the two parts to achieve a high-efficiency conversion system for the solar source.

碩士
國立臺北科技大學
電力電子產業研發碩士專班
98
This thesis provides a hybrid maximum power point tracking method based on both perturbation and observation method and constant voltage method in solar power system. To improve the tracking speed of perturbation and observation method for the power disturbance, the constant voltage method is initially used to retrieve the voltage corresponding to maximum power point. When the input voltage of used converter reaches the calculated voltage, the perturbation and observation method starts up instead. Furthermore, a value range is defined by the calculated maximum voltages, and if the subsequently sensed voltage value falls within this range, the perturbation and observation method is still used for maximum power tracking. On the other hand, if the sensed voltage value does not fall within the range of values, the constant voltage method is reused to track the maximum power point again. That is, the proposed method will omit small power perturbation to decrease the tracking time and oscillation phenomenon at maximum power point by perturbation and observation method, and therefore the loss reduction. To take advantage of this feature, the duty cycle is set as the same as the previous duty cycle while observing to calculate the power to reach the predetermined range. The digital controller HT46F49E MCU is used to implement the proposed maximum power point tracking method and Boost converter is utilized to act the power topology, and experiments conform the predetermined results.

碩士
國立中正大學
電機工程研究所
102
This thesis is mainly about developing a maximum power point tracker for wind power system. Most of conventional maximum power point trackers were constructed from a step-up converter, and adopted P&O as a control method. However, the generator power will dramatically vary based on the enormously fluctuation of the wind velocity and the wind direction. Therefore, this study proposes the T-S fuzzy control method which owns the faster tracking velocity and realizes the high power DC-DC converter with both step up and down functions. By the way, the T-S fuzzy control method is compare with the conventional P&O method. First, this thesis introduces how the wind generator achieves the maximum power point tracking by using a backward converter. Second, the wind power system is modeled for computer simulation. Then, this thesis proposes a robust T-S fuzzy control for the wind power system with decay rate. Last, the T-S fuzzy controller is implemented by using a micro processor. Three kinds of MPPT experiments are conducted. They are single wind power curve with fixed pitch angle, multiple wind power curves with fixed pitch angle, and multiple wind power curves with fixed wind velocity. Experimental results verify that the T-S fuzzy control method tracks more expeditiously and precisely in the rapidly shift of wind farm. The robustness of the wind power system is also discussed.

碩士
國立聯合大學
電機工程學系碩士班
97
In this paper, we study the issue of maximum power tracking control in a wind power generation system. A fuzzy maximum power point tracking (Fuzzy MPPT) control with self-tuned scaling factor is proposed to improve the tracking response of the perturbation and observation (P&O) method. As applying P&O method in maximum power point tracking, a fast tracking would result in large oscillation around the operating point. Hence one has to make a compromise between the tracking speed and the stability of operating point. The proposed method provides a means to resolve this dilemma. In addition, in response to step change in the velocity of the wind, the proposed scheme also outperforms the P&O method. This feature makes the proposed wind power generation system being more applicable. In addition, only output voltage and current, without sensing the wind velocity, rotation speed and torque of the wind turbine, are required in implementing the proposed Fuzzy MPPT, which could reduce the cost and increase applicability in practice. The performance of the proposed Fuzzy MPPT is first verified by computer simulation with MATLAB/SIMULINK software. For experimental verification, a wind power generating system with utility parallel interface is built, in which an eZdsp F28335 development kit is employed to realize the three MPPT controllers: self-tuned and fixed scaling factor Fuzzy MPPT, and P&O method. The experimental results of these MPPT controllers are documented, and comparisons are made to illustrate the feasibility and superiority of our approach.

碩士
崑山科技大學
電機工程研究所
102
Since the solar cell output power is changed with the sunshine and temperature, the solar cell cannot work at the maximum power point at any time, which wastes a lot of power. This dissertation mainly studies a maximum power point tracking method of the solar power, which can track the maximum power output of the solar cell quickly and stable. Even when the weather changes quickly, the proposed method can achieve rapid and precise control of the largest solar power output. The fuzzy-neural network control method is used to realize the maximum power point tracking, which control program is implemented by a dsPIC30F40111 DSP. The voltage and current of solar cell are measured by the dsPIC30F40111 DSP. Then the maximum power point is calculated using the fuzzy-neural network controller, and output PWM signal to control DC-DC converter, which deliver the maximum power of the solar cell to a load to achieve maximum power point tracking control. Finally, experimental results demonstrate that the proposed method can quickly and effectively track to maximum power point of a solar power.

碩士
淡江大學
航空太空工程學系碩士班
103
This thesis presents the development of an integrated computer simulation program for solar power maximum power point tracking system. The simulation framework mainly con-sists of three major parts, a PV simulation model, dynamic model of the SEPIC/Zeta/Synchronous four-switch type buck-boost converters, and fuzzy logic based maximum power point tracking algorithms. The maximum power point is achieved by con-tinuously adjust the duty ratio command for the power converter. First, we integrate the PV model and dynamic model of the converter in pure computer program. The simulation re-sults demonstrate the solar power system is feasible by using pure MATLAB computer pro-gram. Perturb and observe method, incremental conductance method, and fuzzy logic based MPPT controllers are then integrated into the simulation program. Final MATLAB based graphic user interface is designed to facilitate understanding of the MPPT system. The sys-tem can be used for both engineering and education purposes.

碩士
聖約翰科技大學
電機工程系碩士班
102
The thesis describes the design and implementation of power converter with maximum power point tracker for photovoltaic. Boost dc/dc converter is used for power conversion. A simplified perturbation and observation (P&O) method is used for maximum power point tracking (MPPT) which is easier to implement and the oscillation is smaller than traditional P&O. The control algorithm is implemented using PIC16F883 microcontroller and experimental results show the effectiveness to reduce the oscillation around the maximum power point.

碩士
國立中山大學
電機工程學系研究所
100
This thesis discusses the modeling of a micro-grid with photovoltaic (PV)-wind-fuel cell (FC) hybrid energy system and its operations. The system consists of the PV power, wind power, FC power, static var compensator (SVC) and an intelligent power controller. Wind and PV are primary power sources of the system, and an FC-electrolyzer combination is used as a backup and a long-term storage system. A simulation model for the micro-grid control of hybrid energy system has been developed using MATLAB/Simulink. A SVC was used to supply reactive power and regulate the voltage of the hybrid system. To achieve a fast and stable response for the real power control, the intelligent controller consists of a Radial Basis Function Network-Sliding Mode Control (RBFNSM) and a General Regression Neural Network (GRNN) for maximum power point tracking (MPPT). The pitch angle of wind turbine is controlled by RBFNSM, and the PV system uses GRNN, where the output signal is used to control the DC/DC boost converters to achieve the MPPT.

碩士
國立臺灣大學
電子工程學研究所
99
Batteries have been used in many applications in our life. Nevertheless, batteries must be charged by chargers to maintain their electrical energy. There are many different chargers in the market. Because solar energy is clean and inexhaustible, using solar charger is economical and environment friendly. Traditionally, the maximum power point tracker is implemented by a digital microprocessor for high power applications and high cost. However, they are not applied to low-power applications, such as portable electronic devices. Therefore, we attempt to do a research for a maximum power point tracker that can be applied to low-power application and has low cost. The maximum power point tracker is used as a solar charger charging output power from solar cells to batteries. Besides, the MPP tracker is also modified. The MPP tracker has a simplified structure, because only one multiplier is needed. The circuit is implemented by analog design and it has excellent tracking effectiveness. Finally, an experimental circuit is implemented to verify the results. In addition, the thesis compares with the MPP tracker without modification and the modified MPP tracker.

碩士
國立成功大學
航空太空工程學系碩博士班
97
Due to the energy crisis, renewable energy sources have been suggested as the possible solution. Among these sources, solar energy is pollution free and inexhaustible. Therefore it is a fairly good energy to generate electric power. However, the efficiency of solar cell is still very low, for that matter how to make the photovoltaic power system works in maximum power point is important. This thesis focuses on the maximum power point tracking control of photovoltaic power system. Owing to nonlinear I-V characteristics of photovoltaic cells, a maximum power point tracking algorithm is adopted to maximize the output power. In this thesis, An approach for maximum power point tracking using the sliding mode control is proposed. The proposed controller is robust to harsh environment changes and the performance of the controller is verified through simulations.

碩士
國立中正大學
電機工程所
97
This thesis presents design and implementation of a maximum power point tracker (MPPT) with soft switching feature. The converter topology is a boost converter with a turn-on and turn-off passive lossless snubber (one inductor, two capacitors, and three diodes). The MPPT controller is based on a “perturb and observe” algorithm to track maximum power points of PV panels. At first, the types and characteristics of PV panels are introduced, and then, the boost converter and snubber are analyzed. A 4.8 kW MPPT has been implemented to verify its performance, which achieves the highest conversion efficiency of 97%.

碩士
國立高雄應用科技大學
電機工程系博碩士班
96
The thesis investigates the cost analysis of a kind of photovoltaic maximum power point trackers (MPPT) which is based on using the pulse width modulation (PWM) signal as perturb sources. The advantage of such tracker has a good tracking speed without destroying original operation condition when executing maximum power point tracking. However, each of photovoltaic cells shall install a MPPT to insure each photovoltaic cell is operated at maximum power point at the cost of MPPT. In order to make cost analysis, three different groups of photovoltaic cells are subjected into a MPPT and their maximum power efficiencies are discussed. The MATLAB simulation results show two groups of photovoltaic cells subjected into a MPPT provides a lower cost without sacrificing its efficiency.