Manuel A. Perales

Three-dimensional space vector modulation in abc coordinates for four-leg voltage source converters

Four-leg inverters have been selected as one of the preferred power converter topologies for applications that require a precise control of neutral current, like active filters. The main advantage of this topology lies in an extended range for the zero sequence voltages and currents. However, the addition of a fourth leg extends the space vectors from two to three dimensions, making the selection of the modulation vectors more complex. Most of the algorithms that deal with this problem require an /spl alpha//spl beta//spl gamma/ transformation. This paper presents a new space vector modulation algorithm using abc coordinates (the phase voltages) avoiding the /spl alpha//spl beta//spl gamma/ transformation. Thanks to the use of abc coordinates, the algorithm is much simpler and more intuitive than in /spl alpha//spl beta//spl gamma/ representation, drastically reducing the complexity of modulation algorithm and the computational load associated to it.

Three-dimensional space-vector modulation algorithm for four-leg multilevel converters using abc coordinates

In this paper, a novel three-dimensional (3-D) space-vector algorithm for four-leg multilevel converters is presented. It can be applied to active power filters or neutral-current compensator applications for mitigating harmonics and zero-sequence components using abc coordinates (referred from now on this paper as natural coordinates). This technique greatly simplifies the selection of the 3-D region where a given voltage vector is supposed to be found. Compared to a three-level modulation algorithm for three-leg multilevel converters, this algorithm does not increase its complexity and the calculations of the active vectors with the corresponding switching time that generate the reference voltage vector. In addition, the low-computational cost of the proposed algorithm is always the same and it is independent of the number of levels of the converter.

Sliding mode control of a DC/DC PWM converter with PFC implemented by neural networks

An experimental neural controller implementing a variable structure control (VSC) algorithm is proposed for a power factor preregulator. VSC control laws yield fast response and a robust behavior against large parameters variations. A multilayer perceptron learns through backpropagation to approximate the desired adaptive control functions. The main advantage of the neural network implementation in comparison to the numerical implementation is that decreases complexity and cost of the controller, and increases the switching frequency. A simple analog electronic realization of this neural network using discrete operational amplifiers is proposed. This implementation possesses all good properties of sliding mode while avoiding the unnecessary discontinuities of the control input signals and thus eliminating chattering. Experimental results are summarized confirming the validity of the neural network approach.

SVM Procedure for

Space vector modulation (SVM) technique has become a standard method for the impression of voltage references in conventional three-phase voltage source inverters. The method is nowadays used in multiphase (more than three) drives, where linear and overmodulation regions are covered only for the five-phase case. This work proposes a general SVM procedure for linear and overmodulation regions in n -phase drives (being n any odd number, ) and simplifies the extension of SVM to the multiphase case. The proposed method achieves the reference voltage at the fundamental frequency while reducing introduced harmonic components in the overmodulation region compared to previous proposals.

n

In this paper a system to evaluate a variable speed and pitch angle wind turbine by fuzzy logic techniques is described. A fuzzy logic control has been proposed based on the wind speed estimation in order to get maximum power and stability of the system. An 11 kW prototype system using two inverters connected by a DC-link capacitor has been used: the first one works as a controlled rectifier implementing vector control and the second one handles the power injected into the utility grid. Experimental result of an 11 kW generator are shown.

-Phase VSI With Low Harmonic Distortion in the Overmodulation Region

A new, improved, method for calculating the reference of an active filter is presented. This method lays on a new filter, developed by the authors, which is able to extract the main component of a vector signal. Simulation and experimental results confirms the validity of the proposed algorithm.

Fuzzy logic control of a variable speed, variable pitch wind turbine

Thanks to the use of natural coordinates (abc coordinates), the proposed modulation algorithm is much simpler and intuitive than using /spl alpha//spl beta//spl gamma/ representation, reducing the complexity of modulation algorithm and the computational load associated to it. The application chosen, the 4-wire 4-leg inverter, is employed only as an example of how easy the modulation results using this notation instead of classical /spl alpha//spl beta//spl gamma/ representation.

A novel control method for active filters, based on filtered current

In this paper, a novel three-dimensional space vector algorithm for four-legs multilevel converters is presented. It can be applied to active power filters or neutral current compensator applications for compensating harmonics and zero sequence using natural coordinates. This technique greatly simplifies the selection of the 3-D space where a given voltage vector is supposed to be found. The algorithm drastically reduces the algorithm complexity and the calculations of the active vectors with the corresponding switching time which generate the reference voltage vector. In addition, the low computational cost of the proposed algorithm is always the same and it is independent of the number of levels of the converter.

Three dimensional space vector modulation for four-leg inverters using natural coordinates

Open source software represents a new paradigm of software development based on a subjacent community. It is widely accepted in the literature the layered structure of open source communities, being the core group the most active contributors usually located at the center of the community. The tasks of this group include not only an intense activity in terms of contributions but also to promote participation among the rest of the community members. In this paper, the general role of this group is analyzed by modeling communities as Social Networks and applying Social Network Analysis techniques. Findings related their brokerage activity with open source software success.

Simple and advanced three dimensional space vector modulation algorithm for four-leg multilevel converters topology

In this paper we present a control technique for the compensation of selected harmonics in a line using an active filter. We treat the cases where both, voltage source and load current, are under unbalanced operation. Our approach does not belong to the class of high gain controllers (advocated in most conventional approaches to reduce the tracking errors) so we avoid the problems entailed by the excitation of unmodeled dynamics. Moreover, the performance of the system is not limited by the low control bandwidth since we account for the information of the references time derivative (as dictated by classical control theory) and compensate for the unavoidable delay associated with the digital implementation.