S. de Pablo

Project-Based Learning and Rubrics in the Teaching of Power Supplies and Photovoltaic Electricity

Project-based learning (PBL) and cooperative learning are, in various aspects, very superior education methodologies compared to other traditional ones. They are highly appropriate methodologies for elective courses, as they exert a strong attraction on the students, quite apart from their educational advantages. This paper describes how PBL and cooperative learning have been used to teach the topics of power supplies and photovoltaic electricity within two elective undergraduate courses. A project is carried out for each of the two topics. Moodle is used as the e-learning platform to provide the course materials and the wiki resource and to allow the submission of assignments. The simulation is done by means of Simulink. Work has been done to develop skills for project planning, group management of the work, technical document writing and presentations in public. The methodology has been seen to be successful, as all the students who have followed it over the last few years have passed the courses in which it was included, Design of Industrial Applications and Industrial Electronics. Examples of the rubrics for assessing the projects and examples of the projects themselves are also included.

A simpler and faster method for SVM implementation

Space vector modulation is perhaps the common technique mostly applied to drive three-phase voltage-source inverters. During every switching period it calculates three duty cycles in order to generate a suitable pulse sequence. This paper presents a new, faster and, most important, simpler method to compute these time values without using either trigonometric functions or even Clarke or Park transformations. The result is a light-weight algorithm easier to implement in small digital signal processors or microcontrollers. The relationship between SVM and PWM is also explained.

Comparative Analysis of the Techniques of Current Commutation in Matrix Converters

The devices of power used in matrix converters (M.C.) need some operation sequences to commute the current in a safe way. These operation sequences are what we denominate strategies of current commutation, being these more complex than in other converters. In this article a comparative analysis of the different strategies of current commutation will be carried out by means of simulation and they will be implemented in a experimental matrix converter to analyze its behaviour. As comparison criterion of the different strategies that have been used, the total harmonic distortion (THD), the efficiency of the converter, the maximum commutation frequency and the necessary hardware requirements for the implementation of the strategies.

A proposal for ASM++ diagrams

Algorithmic State Machines are a 40-year old tool for the design of digital circuits. They are a good alternative to finite state machines, where only states can be properly described, but actions must be annotated as lateral comments. However, current notation for these diagrams has several limitations for medium-large designs, and often lateral annotations are finally needed. This paper presents an alternative notation for ASM diagrams, trying to overcome these limitations. This new notation is more consistent and thus more convenient for CAD tools.

A novel current control strategy for PWM inverters using the sliding mode techniques

Classical PWM techniques are replaced by current source sliding mode control (SMC) deciding the IGBTs status in real time by using a FPGA. Utility synchronization and inverter management is guaranteed by Park vector transformation. Three novel sliding strategies for current controlled PWM inverters are described, and several simulations show the performance of the inverter control.

ASM++ diagrams used on teaching electronic design

Algorithmic State Machines are a 40-year old tool for the design of digital circuits. They are a good alternative to Finite State Machines, where only states can be properly described, but all operations must be annotated as lateral comments. This paper shows the inner relationship between ASM diagrams and modern languages used to describe hardware and it proposes several modifications to the standard methodology to allow automated tools to produce Verilog or VHDL code from these diagrams. The new notation is more complete and consistent and thus more convenient for CAD tools.

Two novel current source sliding mode control strategies for a 3-phase grid-connected inverter

The control of the status of the 3-phase power switches of an inverter is commonly carried out with classical pulse width modulation techniques due to its simplicity; these techniques compute the status of the 3-phase power switches in a pre-established way, but they do not guarantee high performance because of, for example, load variations. So, the previous techniques are replaced by current source sliding mode control computing the status for the 3-phase power switches in real time; the synchronization with the grid and the inverter management are guaranteed by applying the Parks transformation. Two novel current source vector sliding mode control strategies are described. Several simulations show the performance of the inverter control.

A flexible inverter controller for prototypes

A development tool for research in the field of inverter technology is proposed. The system is divided in two parts: a power subsystem adapted to the application; and a generic FPGA and DSP-based control subsystem. At least four different applications are considered under the same hardware structure, all of them possible with minor changes in the electric circuit layout and specific software executed by a DSP, all controlled from a PC.

Recent advances in ASM++ methodology for FPGA design

This paper reports the latest advances achieved in ASM++ methodology since its presentation in FPGAworld Conference 2007 and 2008. A fully new ASM++ compiler has been built, with an improved graphical interface, but also implementing a fully hierarchical compilation. It allows an easy behavioral description of very low level digital designs at register transfer level (a dual port RAM memory, for example), but it also can manage very complex structural designs with easily reusable components (a small System-on-a-Chip example with a developed USB interface is reported). Using this methodology, each element is described at the proper level of the design hierarchy, in order to be less prone to errors and also to improve design reuse.

A methodology for teaching the integrated simulation of power systems by modeling with MATLAB/SIMULINK and controlling via a C-based algorithm

An adequate methodology to teach integrated simulation of power electronic systems is presented in this paper for undergraduate and postgraduate students, taking into account the advantages of SIMULINK blocksets for modelling, together with C algorithms for controlling, and MATLAB toolboxes for analysis and visualization. The power electronics devices and systems are modelled by using several blocks of the SimPowerSystems library of SIMULINK, whereas the control algorithms (the axes transformation, the utility observer, the link voltage regulator, the currents references generator, and the current source sliding mode control for the converter currents) are written in C and are integrated with SIMULINK via two S-Functions, which are explained in detail. The validity of the proposed methodology is demonstrated through several simulations of the vector control of a 3-phase AC/DC converter, working as an inverter, firstly, and as a rectifier, secondly.