J. C. Aparício Fernandes

Phase Space Signal Filtering

In this article we propose an approach based on the analysis of phase space of time series, in order to improve the filtering process. In some applications the traditional filtering process can produce results that lead to a insufficient representation of the information contained in the signal. Using phase space we can have a different meaning for noise, its correlation with the signal and a supporting theory for accurate filtering.

Experimental comparison of single-phase active rectifiers for EV battery chargers

An experimental comparison of single-phase active rectifiers for electric vehicle (EV) battery chargers is presented and discussed. Active rectifiers are used in on-board EV battery chargers as front-end converters to interface the power grid aiming to preserve the power quality. In this paper, four topologies of active rectifiers are compared: traditional power-factor-correction; symmetrical bridgeless; asymmetrical bridgeless; and full-bridge full-controlled. Such comparison is established in terms of the requirements for the hardware structure, the complexity of the digital control system, and the power quality issues, mainly the grid current total harmonic distortion and the power factor. Along the paper these comparisons are presented and verified through experimental results. A reconfigurable laboratorial prototype of an on-board EV battery charger connected to the power grid was used to obtain the experimental results.

Comprehensive Analysis and Comparison of Digital Current Control Techniques for Active Rectifiers

This paper presents a comprehensive analysis and comparison of digital current control techniques for active rectifiers. These rectifiers are connected to the power grid and are controlled aiming to obtain sinusoidal grid currents and unitary power factor. In this context this paper presents the principle of operation of a full-bridge full-controlled active rectifier, which is controlled by different digital current control techniques, namely, proportional-integral (PI) in stationary frame, PI in synchronous frame, PI sinewave (PIS), feedforward, sliding mode, and predictive. These digital current control techniques are explained in detail and is established a comparison in terms of their current errors in steady-state, as well as in terms of their digital implementation using the digital signal processor (DSP) TMS320F28335 from Texas Instruments.

Evaluation of the introduction of electric vehicles in the power grid – a study for the island of Maio in Cape Verde

This paper presents an evaluation of the introduction of electric vehicles (EVs) in an electrical power grid. The main contribution is the control analysis of the power quality considering simultaneous battery charging processes. The methodology used can be applied to any known power grid; however, it was considered the case of the island of Maio, in Cape Verde, in continuation of previous works concerning that power grid. Two commercial different types of battery chargers were considered: a traditional model with highly distorted current consumption (that causes distortion in the power grid voltage), and another with almost sinusoidal current consumption. Considering simultaneous battery charging processes, it can be concluded that the power grid structure (composed by three medium voltage branches) with the current power demands of the consumers of the island of Maio have a potential integration for 300 EVs if battery chargers with almost sinusoidal current consumption are used, i.e., 152 for the first medium voltage branch, 35 for the second branch, and 113 for the third branch. Moreover, the results show that the first medium voltage branch of the distribution system, which has the capability to support the integration of 152 EVs if the battery chargers have sinusoidal current consumption (presenting a maximum value of THDv % in the power grid voltage of 1.8 %), only can support 27 EVs if are used traditional battery chargers, with highly distorted current consumption (considering a maximum THDv % of 5 %).

A novel architecture of a bidirectional bridgeless interleaved converter for EV battery chargers

This paper presents a novel architecture of a bidirectional bridgeless interleaved converter for battery chargers of electric vehicles (EVs). The proposed converter is composed by two power stages: an ac-dc converter that is used to interface the power grid and the dc-link, and a dc-dc converter that is used to interface the dc-link and the batteries. The ac-dc converter is an interleaved bridgeless bidirectional boost-type converter and the dc-dc converter is a bidirectional buck-boost-type converter. The proposed converter works with sinusoidal grid current and with high power factor for all operating power levels, and in both grid-to-vehicle (G2V) and vehicle-to-grid (V2G) operation modes. In the paper is described in detail the proposed converter for EV battery chargers: the circuit topology, the principle of operation, the power control theory, and the current control strategy. Several simulation results for both G2V and V2G operation modes are presented.

Learning Electronics Project Inside a Control Inspired Conceptual Map

This paper describes two laboratory and project semester modules in the Electronics Engineering programme of Universidade do Minho. Along time, the learning objectives of these modules evolved from integrating conventional laboratory work across disciplines to include first time experience in project of electronics with collaboration of industry. The design of the modules joins elements of conventional laboratory work, project based learning and cooperation with industry. Cooperation with industry has a crucial role in framing the project work and ultimately the laboratory work. Control is, beyond one of the topics to be learned, a main source of inspiration for the design of the modules at large, as the feedback loop concept is used to unify laboratory work from several disciplines with project into a coherent learning experiment.