Page - 85 - in Hybrid Electric Vehicles

is required. In the battery semi-active topology, the supercapacitor is connected to theDCbus directly, while the battery uses a bidirectional DC/DC converter to interface theDCbus. The advantageisthebatterycurrentcanbemaintainedatanearconstantvalue, thusthelifetimeand energy efficiency of the battery can be improved significantly. Themain shortcoming of this topology is that thevoltageof theDCbuswill varyduring thecharging/dischargingprocessof thesupercapacitor.Theparallelhybrid topology isanoptimalchoice that cansolveall theprob- lemsof theabovetopologies.Thedisadvantage is that twoDC/DCconvertersareneededwhich will increase complexity, cost, andadditional losses of the system.Threedifferent topologiesof HESSusingsupercapacitorsasthemainenergystoragedeviceforEVapplicationwereanalyzed bySong et al. [13]. Rothgang et al. studied the performance of an active hybrid topology [14]. Amongthesevariousarchitectures,thesupercapacitorsemi-activehybridtopologyusinglithium- ionbatteriesasthemainstoragedeviceisconsideredasagoodsolutionforHEVapplicationdueto itshigh-powerdensityandlowcost. MostofinvestigationsaboutHESSfocusonEVapplications.HungandWudesignedarule-based control strategy for theHESS of anEVand estimated the systemperformance [15]. Vulturescu et al. tested theperformanceof anHESSconsistingofNiCadbatteries andsupercapacitors [16]. Songetal. compared threedifferent control strategies foranHESS,which includedarule-based control, amodel predictive control, and a fuzzy logic control [17]. AnHESS can also be used with a fuel cell and successfully satisfy the requirements of an FCV [18–20]. However, few investigationsareconcentratedontheapplicationofanHESSforanHEVatpresentbecausethey aremorecomplicatedthanthoseforanEV.Masih-Tehranietal. studiedtheenergymanagement Figure1. Topologiesofhybridenergystoragesystemforvehicleapplication: (a)passivehybridtopology, (b)supercapacitor semi-activehybridtopology, (c)batterysemi-activehybridtopology,and(d)parallelactivehybridtopology. A Hybrid Energy Storage System for a Coaxial Power-Split Hybrid Powertrain http://dx.doi.org/10.5772/67756 85