G. Coquery

Dynamic PEM fuel cell modeling for automotive applications

This paper presents a static and dynamic modeling of a proton exchange membrane fuel cell (PEMFC) for transportation applications. Electrochemical analysis is performed to get an equivalent circuit of the fuel cell, which can be used, in the simulation of the power generator (association of the fuel cell and its converter). Experimental polarization curves and electrochemical impedance spectroscopy (EIS) are used to identify model parameters and to validate simulation results. Finally, experimental response to a current step is compared to the proposed model.

Temperature measurements and thermal modeling of high power IGBT multichip modules for reliability investigations in traction applications

Abstract To study the failure mechanisms induced on high power IGBT multichip modules by thermal cycling stress in traction environment, a good knowledge of the temperature distribution and variations on the chips and in the interfaces between the different layers of the packaging is necessary. This paper presents a methodology for contact temperature measurements on chips surface in power cycling conditions and a fast 3D thermal simulation tool for multilayered hybrid or monolithic circuits. The results of static and dynamic thermal simulation of a 1200A–3300V IGBT module are given and compared with the contact temperature measurements results. The investigation has been done within the RAPSDRA (Reliability of Advanced High Power Semiconductor Device for Traction Applications) European project.

Investigation of the heel crack mechanism in Al connections for power electronics modules

Abstract In power electronic packages, one of the main limiting factors for the module reliability stems from failure of the electrical interconnection which ensures the contact between the chip and the lead frame. The aim of this work is to model, using FEM and some analytical developments, the interconnection heel crack mechanism appearing in service. The forming process impact is particularly evaluated and it is established that the initial residual stresses contribute to limit the wire/ribbon life time.

Fuel cell-based hybrid systems

This paper presents different works which are actually developed in the field of fuel-cell hybrid systems in different public laboratories in France. These works are presented in three sections corresponding to: 1. Hybrid fuel cell/battery or supercapacitor power sources; 2. Fuel-cell multi-stack power sources; 3. Fuel cell in hybrid power systems for distributed generation. The presented works combine simulation and experimental results.

Traction power converter for PEM fuel cell multi-stack generator used in urban transportation

This paper presents the study, based on technical specifications, of a power converter structure candidate to fuel cell multi-stack association for urban transport applications. This study is carried out in the frame of the French SPACT-80 research project. The converter topology is based on a DC-DC 3-phase IGBT interleaved boost converter which should meet the following relevant criteria: high efficiency, redundancy, minimisation of fuel cell current ripple, compactness, fault handling and strategies for degraded working modes. The degraded working modes which are considered are one fuel cell stack or converter phase out of work, and DC bus voltage fluctuation. The originality of this paper consists in the power converter design and the backup strategies. Converter operation and performances are studied by numerical simulation.

First approach for a fault tolerant power converter interface for multi-stack PEM fuel cell generator in transportation systems

This paper presents a fault tolerant architecture for connecting PEM fuel cells inside an hybrid on-board power generation system. As a first approach, the problematic of fault tolerance for multi-stack PEM fuel cell power systems dedicated to battery-hybrid transportation systems will be considered from both sides which closely interact: the fuel cell generator in case of faulty working and the power converter interface. For the first case, the use of antiparallel by-pass diodes have proved to be a solution and are tested on series assembly of 2-cell (experimental validation) and 20-cell (simulation) PEM fuel cell stacks. For the second one, the technological choice of an interleaved multi-phase boost converter interface with backup strategies and fault-tolerance management will be detailed. One of the great issues of these converter architectures is also to give new possibilities for power management and coordination with the battery inside this hybrid transportation system.

Dynamic behavior of a proton exchange membrane fuel cell under transportation cycle load

This paper presents a dynamic modeling of a proton exchange membrane fuel cell (PEMFC) for transportation applications. Based on an electrochemical analysis, it gives an equivalent circuit of the fuel cell which can he used in association with a power electronic converter. Experimental polarization curves and electrochemical impedance spectroscopy (EIS) are used to identify model parameters and to validate simulation results. Finally, experimental responses to a current step and to transportation solicitations is compared to those obtained using the proposed model.

High frequency power converter for PEFC generator architecture based on a multi stacks association for transportation applications

This paper presents the study and experimental validation of a high frequency (HF) power converter used in a powertrain composed of a polymer electrolyte fuel cell (PEFC) generator based on a multi-stack association and dedicated to transportation applications. As a first approach, the architecture of the system presented in this paper has been limited to two fuel cell stacks. An original power converter structure using a HF transformer (HFT) has been chosen. This structure has the main advantage of compactness and is well adapted to the testing of fuel cell generators either in normal or degraded mode (partial failure of one stack); which correspond to real transport operating conditions. Simulation results of the power system are presented and discussed. First experimental results for a normal PEFC working mode are presented and analyzed in this paper including the experimental determination of the power converter efficiency