Fernando Botteron

Space vector modulation for voltage-source inverters: a unified approach

This paper presents a unified approach of the space vector modulation for voltage-source inverters. To demonstrate the proposed unified approach, five fundamental inverters topologies are analyzed: single-phase full-bridge, three-phase three-wire, three-phase four-wire, three-phase four-leg and three-phase three-level inverters. Switching vectors, separation and boundary planes in the inverter output space as well as decomposition matrices and possible switching sequences are derived for each one of these inverters. Experimental results are shown to validate the proposed unified approach.

A new discrete-time voltage controller based on the internal model principle for three-phase voltage source PWM inverters with /spl Delta/Y output transformer

In this paper a new digital voltage controller based on the internal model principle for three-phase inverters with /spl Delta/ transformer at the output is proposed. A dynamic model of the inverter, transformer, filter and load is derived and a decoupling method is proposed. The proposed digital controller is not prone to produce DC components, which that can lead to the output transformer saturation. Additionally, this digital controller result in a simple form and it is well suited for a fixed-point implementation. Experimental results, implemented in 16 bits DSP TMS320F241, validate the theoretical developments and demonstrate the good performance of the proposed controller under both nonlinear balanced and unbalanced loads.

New limiting algorithms for space vector modulated three-phase four-leg voltage source inverter

This paper proposes two novel limiting algorithms for three-phase four-leg voltage source inverters to constrain the command vector inside the polyhedron defined by the boundaries of the inverter linear operating range. The first algorithm uses an inscribed ellipsoid on the polyhedron, and the second one is based on the polyhedron, and the second one is based on the polyhedron boundary planes. A detailed description, with the key points required for a digital implementation of space vector and limiting algorithms, is given. In addition, the output voltages and the inductors currents are dynamically controlled by means of MIMO servo system in dq0 coordinates. These controllers are designed using an optimal discrete linear quadratic regulator technique, which ensures stability for the system at all operating conditions. In order to provide smooth transitions among the different modes of operation, nonlinear MIMO anti-windup algorithms are proposed to dynamically update the controllers servo variables. Finally, experimental results on a 15 kVA PWM inverter fully controlled by a DSP controller, TMS320F241, has been used to validate the feasibility of the proposed algorithm and to demonstrate the performance of the overall system.

On the space vector modulation and limiting algorithms for three-phase four-leg voltage source inverter in abc coordinates

This paper proposes two limiting algorithms for three-phase four-leg voltage source inverters to constrain the command vector inside the dodecahedron defined by the boundaries of the inverter linear operating range in abc coordinates. The first algorithm uses an inscribed ellipsoid on the dodecahedron, and the second one is based on the dodecahedron boundary planes. A detailed description, with the key points required for a digital implementation of space vector and limiting algorithms, is given. In addition, the output voltages controlled by means of MIMO controller in abc coordinates. This controller is designed using optimal discrete linear quadratic regulator technique, which ensures stability for the system. In order to provide smooth transitions among the different modes of operation, nonlinear MIMO anti-windup algorithm is proposed to dynamically update the controller variables. Finally, simulation and experimental results on a 15 kVA PWM inverter controlled by a DSP TMS320F241 are presented to validate the proposed algorithm and demonstrate the performance of the overall system.

High Reliability and Performance PWM Inverter for Standalone Microgrids

In this paper a high reliability and performance single-phase PWM inverter for standalone microgrids is presented. To obtain the before mentioned characteristics this work propose, two different controller structures and a straightforward design methodology for these controllers, based on the internal model principle. In order to validate the proposed design methodology, digital controllers and to demonstrate the steady state and transient performance, experimental results are presented from a 5kVA PWM modulated single phase inverter, fully controlled by a DSP TMS320F2407.

Design and Implementation of a Three-Phase DC-AC Converter for Microgrids Based on Renewable Energy Sources

This paper proposes a three phase DC AC converter for autonomous microgrids based on renewable energy sources. The microgrid topology offer simple control characteristics, where the AC link does not need a complex voltage controller strategy. The DC AC converter (three phase inverter) generates output voltages with very low THD for any type of load. To obtain the before mentioned characteristics for the inverter, this work propose an internal model principle based controller structure in synchronous dq frame, with a reduced sampling and number of poles. With this structure, is possible to considerably improve the stability and dynamic system response, and mainly, the saturation of the low frequency insulating transformer is avoided. Also in this paper, is proposed a straightforward design methodology for the discrete internal model based controller. In order to validate the proposed digital controller structure, the design methodology and to demonstrate the steady state and transient performance, experimental results are presented from a 15kVA SVPWM modulated three-phase inverter, fully controlled by a DSC dsPIC30F4011.

A Practical Approach for Segmentation of Twigs on Samples of Yerba Mate by Digital Image Processing

This paper discusses the implementation of the digital image processing techniques as a method for estimating the contents of twigs in samples of yerba mate. The hardware used in this paper, to obtain the analyzed images, consists of a desktop scanner and a personal computer. Then, using the designed and developed software for this purpose, the digital images obtained were processed and analyzed using a basic segmentation technique such as binarization with histogram thresholding. This paper compares two methods for estimating weight ratios from the binarized image. Preliminary experimental results using the proposed techniques, suggest that it may be estimated with an error less than 4% the percentage of twigs in a given batch of images. The speediness, simpleness and efficiency of the test, compared with current techniques, as well as, the reduced cost of the associated hardware, presents a viable, inexpensive and straightforward alternative if compared with the traditional.

Controladores resonantes para el control de tensión e inyección de corriente de falla en inversores para UPS

A control strategy for PWM inverters used in double conversion UPS systems is proposed. The objectives of this control strategy are to control the inverter output voltage to comply with performance specification given by standards, and control the inductor current to achieve short-circuit and overload protection. The control strategy is composed by two feedback loops, where the inner current loop uses multiple resonant controllers plus a state feedback controller, and in the outer voltage control loop multiple resonant controllers nested with a proportional controller. The proposal is validated by experimental results of a 2kVA single-phase PWM inverter.

Analysis of the Transformer Influence on a Three-Phase Dual Active Bridge DC-DC Converter

In this work, the impact of the high-frequency transformer on the three-phase dual active bridge DC-to-DC converter operation is investigated, using four transformers with different connections: star-star, delta-delta, star-delta and delta-star. The main objective is to evaluate what is the transformer connection that allows the converter to be operated with high efficiency for different voltage conversion ratios and output power. The apparent power requirements of the high frequency transformers and the power semiconductors stress are evaluated, which allows obtaining the soft switching operating range for each transformer connection. The results of the analysis allow to select the most suitable transformer connection for each application.

Design and experimental implementation of a DC-DC boost converter for renewable energy sources

This paper describes the study and the experimental implementation of a DC-DC boost converter used for photovoltaic solar arrays or energy storage banks. A 5 kW boost converter design with an input voltage between 100-120 V and a regulated output voltage of 400 V is carried out. A photovoltaic solar array or a battery bank can be used as input voltage source and single-phase or three-phase PWM inverters are connected at the boost converter output, which operate as electrical interface in microgrids. The performed analysis is validated by simulation and experimental results which show a suitable dynamic performance under steady and transient state for any kind of load.