Search Results

The microhybrid electric vehicle (MHEV) has increasingly received attention since it holds promise for significant increases in fuel economy vs. traditional gasoline vehicles at a lower price point than hybrid vehicles. Passive parallel connection of the traditional 12V lead acid battery and a high power lithium ion battery has been identified as a potential architecture that will facilitate fuel economy improvements with minimal changes to the electrical network. Enabling a passive dual-battery connection requires a design match between the two batteries, including characteristics such as battery size and resistance, so that the performance can be optimized. In this work we have developed a hybrid model that couples electrochemical model of lithium ion battery (NMC-Graphite as an example) and an equivalent circuit model of lead acid battery in order to study the behavior of 12V dual-battery microhybrid architectures.

Start-stop, aka engine-stop or idle-stop, technologies are increasingly being applied to automotive vehicles to increase fuel economy. Start-stop vehicles turn off the engine during periods of zero speed and/or during prolonged coast down. During engine-stop, the vehicle electronics are powered solely by the battery. To replenish the battery, the battery needs to be recharged. In typical ICE vehicles, the battery is continuously charged. However, fuel economies can be improved if strategic charging of the battery can be achieved through selective charging through the alternator or through regenerative braking. To optimize fuel economy, an accurate estimation of the battery state of charge (SOC) during vehicle operation is required. Although state of charge estimation has mainly focused on Li-ion batteries, lead-acid batteries may be used successfully in start-stop applications.