Rui Chibante

A new physics based SPICE model for NPT IGBTs

A physics based, non-punch-through, insulated gate bipolar transistor (NPT-IGBT) model is presented, as well as its porting into available circuit simulator SPICE. Developed model results in a system of ODEs, from which time/space hole/electron distribution is obtained, and is based on solution of ambipolar diffusion equation (ADE) through a variational formulation, with one-dimensional simplex finite elements. Model implementation, in a circuit simulator, is made by means of an electrical analogy with the resulting system of ODEs. Other parts of the devices are modeled using standard methods. Thus, this new hybrid model combines advantages of numerical and mathematical methods, through modeling charge carrier behavior with high accuracy even maintaining low execution times.

Finite-Element Modeling and Optimization-Based Parameter Extraction Algorithm for NPT-IGBT s

A finite-element, physics-based, non-punch-through (NPT) insulated gate bipolar transistor (IGBT) model is presented in this paper. The models core is based on solving the ambipolar diffusion equation through a variational formulation, resulting in a system of ordinary differential equations (ODEs). The approach enables an easy implementation into a standard SPICE circuit simulator. The resulting system of ODEs is solved as a set of (current controlled) RC nets describing charge carrier distribution in a low-doped zone. Other zones of the device are modeled with classical methods. This hybrid approach describes the devices dynamic and static behavior with good accuracy while maintaining low execution times. As physics-based models need a significant number of parameters, an automatic parameter extraction method has been developed. The procedure, based on an optimization algorithm (simulated annealing), enables an efficient extraction of parameters requiring some simple device waveform measurements. Experimental validation is performed. Results prove the usefulness of the proposed methodology for the efficient design of power circuits through simulation.

An experimentally optimized PEM fuel cell model using PSO algorithm

This paper presents a semi-empirical fuel cell model with parameters identified using an optimization approach. The Proton Exchange Membrane Fuel Cell (PEMFC) model is characterized by technological and empirical parameters and their identification is a hard task if is intended to have precise simulation results in a wide range of operating conditions. It is verified that the Particle Swarm Optimization (PSO) method is an adequate tool to extract the correct parameter values. This is achieved minimizing the difference between experimental and simulated results. Both PEMFC model and PSO algorithm are implemented in Matlab/Simulink software.

Arc-Induced Long-Period Fiber Gratings in the Dispersion Turning Points

We demonstrated the possibility to inscribe long-period fiber gratings (LPFGs) in a B/Ge codoped fiber by using grating periods shorter than 150 μm. We also have arc-induced in the SMF 28 fiber an LPFG in the dispersion turning points by using a grating period of 197 μm. In previous works, the shortest periods were, respectively, of the order of 190 and 320 μm for the same fibers. To achieve such a considerable reduction in the grating periods which enables access to the higher order cladding modes (higher sensitivity), we have developed a high-voltage power supply that allows for a constant and stable electric current ranging from 10.5 up to 21 mA. Computer simulations were used to identify the cladding mode resonances for each grating inscribed in the different fibers. The fabricated LPFGs were characterized as a function of the external refractive index from 1.33 up to 1.42, and an average refractive index sensitivity of -720 nm/RIU in the 1.33-1.41 range was obtained for a 192-μm LPFG without further optimization, such as the use of etching or thin films deposition.

Modeling Buffer Layer IGBTs with an Efficient Parameter Extraction Method

A finite element physics-based punch-through IGBT model is presented, as well as its porting into standard circuit simulator SPICE. Developed model is based on solving the ambipolar diffusion equation (ADE) trough a variational formulation, resulting in a system of ODEs, from which charge carrier distribution is obtained. Implementing the model in a circuit simulator is made by means of an electrical analogy with the resulting system of ODEs. Other parts of the devices are modeled using conventional methods. The paper also discusses a parameter extraction procedure using an optimisation algorithm in order to get an efficient extraction of large number of parameters needed for physics-based IGBT models. Model is validated comparing experimental and simulated results

Arc-induced gratings in the turning points

We demonstrated the inscription of arc-induced long-period fiber gratings (LPFGs) in the B/Ge co-doped fiber and in the SMF28 fiber by using grating periods shorter than 150 μm and 200 μm, respectively. This achievement was a result of the development of a high voltage power supply that allows for a constant and stable electric current ranging from 10.5 mA up to 21 mA. The fabricated LPFGs were characterized as a function of the external refractive index from 1.333 up to 1.420 and a refractive index sensitivity of the order of 1000 nm/RIU was obtained without further optimization.

A soft-switching DC/DC converter to improve performance of a PEM fuel cell system

This paper presents a soft-switching dc/dc converter with ZCS to improve the performance of a PEM fuel cell as a power generation system. The first part of the paper presents an appropriate model for the fuel cell behavior based on analytical formulation of chemical processes behind fuel cell operation and the design of an equivalent and analogue electrical circuit describing the fuel cell operation. A method to extract the set of parameters needed for modeling and to optimize their values is also presented. For the validation of this approach experimental tests are performed with a commercial fuel cell system. The dynamics of the fuel cell model and the dependency on operation point are analyzed. In fact, the dynamics of the fuel cell must be taken in account for an accurate characterization of the fuel cell as a power generation unit. As a power generation unit the fuel cell must be integrated with a dc/dc converter able of controlling the system operating as a dc regulated Voltage source and controlling the fuel cell MPPT, maximizing the generated energy. Authors purpose in the second part of the paper a topology this dc/dc converter based on resonant operation, which allows a soft-switching commutation, and consequently a high efficiency operation. Analysis on selected topology choice, the control and design of the converter are performed. Carried out results show that the controller needs to have a dynamic derivative component in order to ensure a good regulation of output voltage for different load conditions and disturbances on them. The overall system is validated using Matlab/Simulink models.

DYNAMIC MODELING AND SIMULATION OF AN OPTIMIZED PROTON EXCHANGE MEMBRANE FUEL CELL SYSTEM

Hydrogen and fuel cells are widely regarded as the key to energy solutions for the 21st century. These technologies will contribute significantly to a reduction in environmental impact, enhanced energy security and development of new energy industries. Fuel cells operating with hydrogen have the potential to contribute to the transition for a future sustainable energy system with low-CO2 emissions. In this paper a dynamic PEM fuel cell model, implemented in Matlab/Simulink, is presented. In order to estimate the PEM fuel cell model parameters, an optimization based approach is used. The optimization is carried out using the Simulated Annealing (SA) algorithm. This optimization process evolves converging to a minimum of the objective function. The flexibility and robustness of SA as a global search method are extremely important advantages of this method. A good agreement between experimental and simulated results is observed. This optimized PEM fuel cell model can significantly help designers of fuel cell systems by providing a tool to perform accurate design and consequently to improve system efficiency.Copyright

A physics-based power diode model optimized through experiment based parameter extraction

This paper presents a physics-based power diode model with parameters established through an extraction procedure validated experimentally. The core of the model is based on a finite element approach that solves for electron/hole concentration in low doped zone of the device. As physical based models need a significant number of parameters an automatic parameter extraction method has been developed. The procedure, based on an optimization algorithm (simulated annealing), enables an efficient extraction of parameters, needed for physics-based semiconductor models, requiring some simple device waveform measurements. Implementation of developed power diode model, in SPICE like simulators, and extraction procedure is presented. Experimental validation is performed.

A simulation tool to promote active learning of controlled rectifiers

The use of interactive simulation tools can effectively support the adoption of active learning methodologies in Engineering Education therefore increasing the motivation of the students and improving their knowledge acquisition. This paper presents the design and development of a pedagogical simulation tool for the teaching and self‐studying of thyristor controlled rectifiers. The application enables the user to vary the thyristors firing angle and to analyze its influence on the rectifier output voltage. Waveforms are plotted using specific heuristics instead of solving the system of equations that governs the circuits operation which makes the application extremely fast. The software is also independent of the operating system and does not require any kind of installation. In comparison with other existing tools, the proposed system provides a much simpler approach, user‐friendlier, and with an easier learning curve. Evaluation results showed that students reported a positive feedback from the use of the simulation tool.