H. Gualous

Experimental study of supercapacitor serial resistance and capacitance variations with temperature

This paper treats an experimental study of the electrical and the thermal behavior of supercapacitors for power electronics and transportation applications. In this study, the charge and discharge of supercapacitors have been characterized by taking into account the temperature variations of the device and its environment. Thermal dependence of supercapacitor serial resistance and capacitance is determined experimentally. An equivalent circuit is proposed to describe the electrical and the thermal behavior of the supercapacitors. The equivalent circuit is implemented in Saber and Spice software for simulations. Experimental and simulation results are presented, analyzed and compared.

Experimental study of temperature effect on ultracapacitor ageing

Reliability is the key issue concerning ultracapacitor applications. In several power applications ultracapacitors are charged and discharged at high current which causes ultracapacitors heating. This paper presents ultracapacitor ageing according to the temperature. To investigate this effect, a test bench of accelerated ageing of ultracapacitor is carried out. Experimental tests are realized at constant temperature when the ultracapacitors are polarized at the maximum voltage. To quantify the ultracapacitor ageing, the equivalent series resistance (ESR) and the equivalent capacitance (Cequi) are measured using Electrochemical Impedance Spectroscopy (EIS). The cause of this ageing is the degradation of the electrolyte and the activated carbon. The electrolyte decomposes during the oxydoreduction phenomena which creates by-products. This degradation leads to an increase of the Equivalent Series Resistance. These by-products deteriorate also the surface of the activated carbon which generates the reduction in the capacitance. After these tests, the ultracapacitor lifetime is obtained versus temperature for the fixed voltage. With the use of the law of Arrhenius the ultracapacitor lifetime is generalized at all the temperatures but always for an extreme voltage which is the nominal voltage of the component. Finally, other tests on various ultracapacitors are made to generalize the lifetime of the ultracapacitor according to the temperature.

Hybrid auxiliary power unit (APU) for automotive applications

This paper describes the design and control requirements of an auxiliary power unit (APU) for transportation applications. The design of the APU is based on an association of supercapacitors and a proton exchange membrane (PEM) fuel cell. Supercapacitors are incorporated to satisfy peak power demands in order to optimize performance of the APU and to reduce the size and therefore the cost of the fuel cell. After the system description, simulations are done to optimize the DC/DC converter between the APU components and the DC bus of the vehicle. Finally, experimental results are presented and analyzed.

Lithium-ion capacitor — Advanced technology for rechargeable energy storage systems

This paper presents the electrical and thermal behaviour of an advanced lithium-ion capacitor (LIC) based rechargeable energy storage systems. In the proposed study, an extended statistical analysis has been performed to evaluate the main electrical parameters such as resistance, power, capacitance, rate capabilities, variation between cells and thermal parameters. Based on the performed analysis, an electrical model has been developed for dimensioning and evaluation of various applications based on lithium-ion capacitor technology.

Power management of an embedded fuel cell - supercapacitor APU

This paper presents the design, realization and power management of an auxiliary power unit (APU) dedicated to vehicle applications. The proposed APU is based on a parallel arrangement of a polymer electrolyte fuel cell (PEFC) and a supercapacitor bank. Using such an arrangement, the PEFC provides only the mean power to a 42 V DC embedded bus, whereas the supercapacitors bank is sized to respond to the electrical power requirements during transients

Lithium Iron Phosphate - Assessment of Calendar Life and Change of Battery Parameters

This paper represents the calendar life cycle test results of a 7Ah lithium iron phosphate battery cell. In the proposed article and extended analysis has been carried out for the main aging parameters during calendar life and the associated impact of the used battery model. From the analysis, it has been showed that the impact of high temperatures and state of charge is harmful for the lifetime of the battery. Therefore, there is a need for having a dedicated control strategy for keeping the battery in the most appropriate operating condition. The FreedomCar battery model parameters have been analyzed during calendar life.

Artificial neural network control and energy management in 42 V DC link

This paper deals with an experimental realization of a 42 V hybrid power sources for automotive applications. Its composed by a battery which provides the power in constant mean power and a supercapacitor tank in order to supply power in transient state. Two DC/DC converters are used to adapt voltage and current levels between the 42 V DC link, battery and supercapacitor tank. Voltage is regulated by using artificial neural networks (ANNs)

Analysis of Nickel-Based Battery Technologies for Hybrid and Electric Vehicles

In this study, a comprehensive analysis has been performed for the evaluation of the performances of nickel–metal hydride and nickel–cadmium battery cells under different environmental conditions such as temperatures (10, 25, and 40xa0°C), current rates, and states of charge for battery electric vehicles. The selected cells where F-size with capacities of 13xa0Ah for NiMH and 7xa0Ah for NiCd.