This study analyses a novel technique for obtaining a voltage conversion ratio greater than one in a bidirectional seriesresonant DC/DC converter (SRC). The converter works in a discontinuous mode: it transfers energy in packets, but it also accumulates some packets in order to raise the output voltage. This study presents a comprehensive theoretical analysis for the two modes: the step-down mode (common mode) and the novel step-up mode. The converter transfers energy during fixed time intervals (called states), and it is also able to accumulate energy in a novel state called the accumulation state. With this, the circuit can achieve a voltage conversion ratio of up to two. In addition, a design methodology is presented, and it is validated in the design of a high-current bidirectional DC/DC converter for battery applications. The results of the voltage conversion ratio and efficiency measurement are presented along with a comparison with an resonant LLC converter. The converter reaches an efficiency rate of 91% and the voltage conversion ratio varies from 0.8 to 1.22 at maximum power. Using this novel technique, the SRC can now be used in a bidirectional DC/DC converter applied to energy storage devices, such as batteries or supercapacitors.
This paper presents a MATLAB/Simulink simulation model for a Direct Space Vector modulated Matrix Converter (MC). The power circuit model, consisting of an input filter, a matrix of bidirectional switches and an RL load, is completely implemented using the power library in Simulink, contributing to the simplicity and clearness of the whole model. Two switching strategies are modeled, simulated and analyzed together with the Direct Space Vector Modulation (DSVM): Symmetrical SVM and Asymmetrical SVM. Two sets of rules are proposed for these techniques in order to simplify the model implementation. Principal input and output converter variables are presented in simulations so that MCs' characteristics and advantages can be observed. Moreover, this model is also very flexible about changing the modulation technique, the load, or removing the input filter, making it suitable for an introduction of this kind of converters in an educational environment.
The introduction of fully electric vehicles (FEVs) into the mainstream has raised concerns about the reliability of their electronic components such as IGBT. The great variability in IGBT failure times caused by the very different operating conditions experienced and the stochasticity of their degradation processes suggests the adoption of condition-based maintenance approaches. Thus, the development of methods for assessing their healthy state and predicting their remaining useful life (RUL) is of key importance. In this paper, we investigate the results of performing accelerated aging tests. Our objective is to discuss the design and the results of accelerated aging tests performed on three different IGBT types within the electrical powertrain health monitoring for increased safety (HEMIS) of FEVs European Community project. During the tests, several electric signals were measured in different operating conditions. The results show that the case temperature (TC), the collector current (IC), and the collector-emitter voltage (VCE) are the failure precursor parameters that can be used for the development of a prognostic and health monitoring (PHM) system for FEV IGBTs and other medium-power switching supplies
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