Gérard Coquery

Study of Accelerated Aging of Supercapacitors for Transport Applications

One important part of the electrical transportation systems is the energy-storage system. This can be based, for example, on supercapacitors. In this paper, we propose to study its behavior under constraints similar to their uses in power and railway-traction systems. We define an adequate measurement protocol for accelerated aging which is applied to supercapacitors according to two accelerated factors: effective current and temperature. We model the supercapacitors for different states of health. The modeling gives a good estimation of the variation of electrical parameters of the supercapacitor at different states. We reveal general indicators of the supercapacitors aging, and we discuss about its life cycle.

Space-Vector PWM Control Synthesis for an H-Bridge Drive in Electric Vehicles

This paper deals with a synthesis of space-vector pulsewidth modulation (SVPWM) control methods applied for an H-bridge inverter feeding a three-phase permanent-magnet synchronous machine (PMSM) in electric-vehicle (EV) applications. First, a short survey of existing architectures of power converters, particularly those adapted to degraded operating modes, is presented. Standard SVPWM control methods are compared with three innovative methods using EV drive specifications in the normal operating mode. Then, a rigorous analysis of the margins left in the control strategy is presented for a semiconductor switch failure to fulfill degraded operating modes. Finally, both classic and innovative strategies are implemented in numerical simulation; their results are analyzed and discussed.

Ageing study of a supercapacitor-battery storage system

This paper presents a preliminary study about a battery ageing methodology of a storage system formed by supercapacitors and lead-acid battery. The design of the hybrid system, based on a simple power flow management - the battery current clipping - is briefly summarized in order to outline the main benefit of the hybridization: the reduction of losses within the battery. The experimental setup will allow quantifying the impact of the hybridization on the battery lifetime by means of energy exchange between two energy storages, the hybrid one and a battery.

Corrective action with power converter for faulty multiple fuel cells generator used in transportation

This paper deals with the corrective action with a power converter for a 100kW multiple fuel cells (FC) generator under fault and used for vehicle propulsion, or high power onboard electrical assistance. The objective is to permit, through the power converter and its control strategy, a soft shut-down of a FC stack in fault and guarantee a continuous of operation at a reduced power, acceptable by the specifications. The power converter should also realize the power management during the degraded working situation. Two power system architectures are studied and compared by numerical simulation.

Description of supercapacitor performance degradation rate during thermal cycling under constant voltage ageing test

Great research effort is currently devoted towards enhancing performance and operating time of electrical vehicle (EV). Classic storage element in EV consists of accumulators, which allow a relatively high autonomy. However, the power capability of these devices can be considered as insufficient. Supercapacitors (SC) are a new promising storage system used in EV to minimize this lack thanks to their high power capability. One of the ageing cause for SCs for this application is the day/night cycling, that is why we study the impact of thermal cycling on SC performances in this paper. In this article, and in order to have a descriptive sample, impacts of three thermal cycling ageing test conditions are compared with obtained results coming from simple calendar ageing tests at constant temperature and voltage. The comparison is based on physics modelling parameters evolution in the Constant Phase Element (CPE) and Multi-Pore (MP) models. These parameters are calculated based on experimental measurements during calendar ageing tests up to 14,000 h and 6000 h, 10,000 h for thermal cycling tests. Finally, the study of modelling parameters highlights changes in the internal physical structure for both ageing tests.

Fault detection and identification using simple and non-intrusive on-line monitoring techniques for PEM fuel cell

This paper scope is centered in the PEM fuel cell stack health diagnosis. For this purpose, authors present fault detection and identification methods using simple and non-intrusive on-line monitoring techniques. The approach is gradual based on detection and identification methods applied to a single cell up to multi-cells stacks used for power applications like transportation. A very low number of sensors are needed for the monitoring and the technique can be implemented on-line. Numerical simulation results illustrate the advantages of the different techniques.

Electrical architecture for high power segmented PEM fuel cell in vehicle application

In the objective of power increase for transport applications or on-board auxiliaries systems, long fuel cell stacks may be subject to disparities (fluidics, temperature) and can be the cause of possible failures. Coupled with a fault detection strategy, the power converter associated with the fuel cell can act to manage the fault. This article is about power converter topologies applied to a segmented high power fuel cell. The fuel cell generator is a 3-part segmented Polymer Electrolyte Membrane (PEM) fuel cell. Each fuel cell segment can be controlled independently according to its state of health (SoH). The converter topology has to be simple, compact, reliable and with a high efficiency. The resonant isolated boost as converter “technology brick”, allowing soft switching is a candidate topology to meet the technical specifications of the multi-port fuel cell-converter system.

Ageing quantification of supercapacitors during power cycling using online and periodic characterization tests

In this paper, a testing methodology for ageing quantification of supercapacitors (SC) for hybrid electric vehicles (HEV) applications is investigated. The accelerated ageing tests are based on power cycling and on the definition of a current profile that takes into account the high charge-discharge current levels of typical HEV functionalities. An online characterization method is used to follow the degradation of the cells performances in terms of evolution of capacitance and equivalent series resistance. The reproducibility of the measurements allows quantifying the impact of both the voltage and the temperature on the ageing for a significant number of cycles. Then, the regeneration phenomenon that appears during the power cycling stops is highlighted and its real impact on the cycle life is discussed. This database of experimental results will be used further to develop ageing laws that will be implemented in SC simulation models in order to optimize the sizing of the cells for a given HEV application.

Optimization of wire connections design for power electronics

Abstract In automotive power electronics, low cost and reliability requirements both demand to optimize each part of the package in order to increase its life time during use. The wire bonding breakage accounts for one of the most common failures observed on power modules. In particular, the heel crack mechanism, mainly due to Joule self-heating, can occur in the module, leading to its death. Thus, the wire geometry design has to be set up to maximize its endurance. This paper presents an analytical method able to predict the optimal wire length regarding a wire displacement criterion. Finally, comparisons between experimental results and predictions of the analytical model are given.

Design of a supercapacitor-battery storage system for a waste collection vehicle

This paper deals with the design of battery-supercapacitors energy storage for an electric waste collection vehicle. The vehicle was simulated on an urban driving cycle and a simple power flow management based on the power limitation in battery was developed. The main benefit of the hybridization, the reduction of the losses within the battery, is outlined and we show how the ultracapacitor pack could be designed in order to prevent stress on battery and, consequently, to extend its lifetime.