Fuel Cell Powered Vehicles Using Supercapacitors–Device Characteristics, Control Strategies, and Simulation Results

Abstract

The fuel cell powered vehicle is one of the most attractive candidates for the future due to its high efficiency and capability to use hydrogen as the fuel. However, its relatively poor dynamic response, high cost, and limited life time have impeded its widespread adoption. With the emergence of large supercapacitors (also know as ultracapacitors, UCs) with high power density and the shift to hybridization in the vehicle technology, fuel cell/supercapacitor hybrid fuel cell vehicles are gaining more attention. Fuel cells in conjunction with supercapacitors can create high power with fast dynamic response, which makes it well suitable for automotive applications. Simulation results show that hybridization of fuel cell vehicles with supercapacitors with load leveling control can significantly reduce the stress on fuel cells electrically and mechanically and benefit fuel economy of the vehicles. Compared to fuel cell vehicles without energy storages, fuel cell-supercapacitor hybridization achieved fuel economy increases of up to 28% on the FUDS cycle and up to 24% on the US06 cycle for mid-size passenger vehicles. In general, the maximum fuel economy improvements are greater using supercapacitors than batteries. The simulation results show that the power assist control strategy is better than load-level control for batteries because of the lower losses in the DC/DC converter and batteries, but load level control is better for supercapacitors. The best approach for hybridization of the fuel cell vehicles is to use supercapacitors with load leveled control as it greatly mitigates the stress on fuel cells and results in a near maximum improvement in fuel economy and fuel cell durability.

An innovating application of PEM fuel cell: Current source controlled by hydrogen supply

“…Indeed, the interface converter represents additional volume and weight for the system, and may moreover induce extra energy losses. For example, H. Zhao and A. F. Burke [2] demonstrate that for fuel cell vehicle applications, this direct connection of a fuel cell with a storage device can increase the hybrid source efficiency and achieve significant fuel economy (notably if supercapacitors are used), in comparison with a typical association with an interface converter. Other example, T. Yalcinoza and M. S. Alama naturally consider in [3] fuel cell/supercapacitors direct hybridization for portable applications (namely, a laptop computer).…”

The Composite Supercapacitor

“…[5] (4) Thep rovision of transient power assistance to fuel cells of very low power density. [6,7] Although supercapacitors are preferred for high-power applications,d ifferent supercapacitor applications,e ven within the same field, have different requirements for the maximum energy-to-power ratio that naturally do not alwaysm atch exactly the energy-to-power ratios of existingo ro ff-the-shelf supercapacitors.F or example,t he different requirements for supercapacitors in the FreedomCAR project of the United States Advanced BatteryC onsortium (USABC) [8] include a1 2Vtransient start-stop( TSS) application with an energyto-maximum-power ratio of 15 Wh/4200 W = 12.9 s, a4 2V start-stop( FSS) application with an energy-to-maximumpower ratio of 30 Wh/6000W= 18 s, and a4 2V transient power assist (TPA) application with an energy-to-maximumpower ratio of 60 Wh/13000 W = 16.6 s. In an example for grid applications,s upercapacitor requirements in two different functions include supercapacitors to ensure power quality with 0-5 sd ischarge and up to 1min capacity and supercapacitors for regulation with secondso fd ischarge and capacity.…”

Active management of a heterogeneous energy store for electric vehicles

“…The alternative is to consider a heterogeneous system in which high energy and high power density are achieved with separate technologies. This approach has been previously explored with promising results for various hybrid electric vehicles, including both hydrogen and petrol fueled vehicles [2]. These hybrids usually use the electric subsystem to handle the high-rate demands, allowing the other subsystem to operate in a maximally efficient manner [3].…”