Power distribution control coordinating ultracapacitors and batteries for electric vehicles

• Published in: 2004 American Control Conference Proceedings; Volume 5 of 6 Vol. 5; pp. 4716 - 4721 vol.5
• Main Authors: Ozatay, E., Zile, B., Anstrom, J., Brennan, S.
• Format: Conference Proceeding Journal Article
• Language: English
• Published: Piscataway NJ IEEE 01.01.2004; Evanston IL American Automatic Control Council
• Subjects: Applied sciences; Battery powered vehicles; Computer science; control theory; systems; Control system synthesis; Control systems; Control theory. Systems; Costs; Electric vehicles; Energy storage; Exact sciences and technology; Fluctuations; Fuel cells; Hybrid electric vehicles; Power distribution; Supercapacitors; Energy cost; Hybrid vehicle; Control synthesis; Secondary cell; Load frequency control; Replacement; Electric vehicle; Electrical network; Power control; Battery; Supercapacitor; Capacitor; Fuel cell; Energy storage
• ISBN: 9780780383357; 0780383354
• ISSN: 0743-1619
• DOI: 10.23919/ACC.2004.1384057

Electrical energy storage is a central element to any electric-drivetrain technology - whether hybrid-electric, fuel-cell, or all-electric. A particularly cost-sensitive issue with energy storage is the high replacement cost of depleted battery banks. One possibility to ease the power burden on batteries and fuel cells is to use ultra-capacitors as load-leveling devices. The high power density of ultra-capacitors allows a significant reduction in the power fluctuations imposed on the remaining electrical system; however, the same ultra-capacitors have a very low energy density and therefore must be used sparingly and with coordination. A control strategy for coordinated power distribution is a central issue for ultracapacitor-supported systems. Toward this end, several control methods are implemented on an electric vehicle equipped with a battery/ultracapacitor system with the goal of improving battery life and overall vehicle efficiency. A particular goal is to obtain both a peaking load control and a frequency-weighted coordination between capacitor and battery in order to mitigate transients in the battery current demand. A key control design issue is that the control objectives vary with respect to vehicle velocity, driver's power demand, and state-of-charge of both the batteries and ultracapacitors.