| Abstract |
The performance versus cost tradeoffs of a fully electric, hybrid energy storage system (HESS), usinglithium-ion (LI) and lead-acid (PbA) batteries, are explored in this work for a light electric vehicle (LEV).While LI batteries typically have higher energy density, lower internal resistance and longer lifetimethan PbA batteries, the module cost of LI batteries are typically three to five times the cost of PbAbatteries. The objective is to design a HESS configuration that 1) is cost-competitive with a PbA singleenergy storage system (SESS) and 2) maintains most of the performance benefits of a lithium SESS.A modular HESS architecture with a bi-directional dc-dc converter and controller is proposed, and apower-mix algorithm with active inter-chemistry battery state-of-charge (SOC) balancing is presented,simulated, and verified experimentally. The batteries, converter and control algorithm are modeled inMATLAB, and the effects of total ESS energy, vehicle loading, DOD, and speed are explored. The costand performance of the HESS are assessed side-by-side with PbA and LI single energy storage system(SESS) configurations of comparable total energy, using expected vehicle range as the performancemetric. The experimental HESS has a total projected cost midway between the SESS PbA cost and theSESS Li cost, while providing 17\% range and 22.5\% efficiency increase over the SESS PbA vehicle. |
