This paper presents a rigid sensorless dc-dc converter for charging the ultracapacitors of ultracapacitor-battery hybrid systems. Lithium-polymer batteries (LiPo) have been applied for electric vehicles (EV) since the energy densities are high. However, the output power of LiPo batteries may be inadequate for certain operations like hill-climbing and rapid acceleration. The performance of the battery systems can be improved by using ultracapacitors because of their high power densities and low equivalent series resistances. Ultracapacitors can smooth the pulsating loading current. Common chargers usually consist of current transducers and closed-loop control circuits, but they are not optimized for ultracapacitors. Although the charging current can be kept constant, peak input current is required and battery current varies during the charging process. However, the onboard chargers for ultracapacitors are powered by batteries and flat input current profiles are preferable. Since a flat load profile can extend the life cycle as well as the usable capacity of a battery. The new charger consists of only five major components. It requires no current transducer and no closed-loop control circuitry, but the input current will be constant and the charger is free of stability problem. Both experimental and simulation results are included in this paper.
A dedicated charger for hybrid energy systems with ultracapacitors and lithium-polymer batteries
Ein spezielles Ladegerät für Hybridenergiesysteme mit Ultrakondensatoren und Lithium-Polymer-Batterien
2006
11 Seiten, 14 Bilder, 2 Tabellen, 12 Quellen
Aufsatz (Konferenz)
Datenträger
Englisch
COMPARISONS OF LITHIUM-ION BATTERIES AND ULTRACAPACITORS IN HYBRID-ELECTRIC VEHICLE APPLICATIONS
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