A Study On Development Of A Plug-in Hybrid Electric Vehicle

Plug-in Hybrid Electric Vehicle (PHEV), a new energy-saving and environmentalvehicle, derives from the traditional HEV. PHEV can be seen as an intermediate technologybetween BEV and HEV, which is an oil-electricity mixed hybrid electric vehicle with twooperation modes．While batteries are fully charged，it can run on pure electric mode whichcan meet the on—off work without any oil．During long distance traveling，it will switch tohybrid mode when state of charge(soc) reaches the low limit．Compare with the internal combustion engine automobile and conventional HEV, thePHEV drives the automobile more depend on battery, so its fuel economy got the furtherimprovement, the carbon dioxide and the nitrogen oxides exhaust also less. It can indeed beconsidered as either a BEV supplemented with an internal combustion engine (ICE) toincrease the driving range, or as a conventional HEV where the all-electric range is extendedas a result of larger battery packs that can be recharged from the grid. PHEV can be seen as akind of good interim technology before the battery developments (performance and cost) didnot obtain successes. The auto conglomerates have already released PHEV car types ordevelopments plans at present, as a direction of development，PHEV has a wide market.A plug-in hybrid electric vehicle can be designed with the same types of technologicalarchitecture as current hybrid vehicles, namely series-hybrid, parallel-hybrid, or combinedseries-parallel hybrid。Firstly，a serial hybrid architecture is selected after comparing threekinds of architectures．The serial hybrid architecture has the simplest structure and heinternal combustion engine can work in the best fuel economy and emission range.For PHEV, the three key problems are battery, motor and Energy management.Considering the investigation report that around half the passenger cars in the U.S. drives less than25miles (40km) a day and80%less than50miles (80km), a64km AER wasassumed. The energy capacity13kwh is required by64km AER. The volume and mass ofon board battery have to be considered, The batteries have different category because of thedissimilarity of the material and craft, there is very big dissimilarity in the specific energy(Wh/kg),energy density (Wh/l), Lifetime, safety, costs and environmental protection etc.Li-ion batteries have been testing intensively worldwide and are already used on manyPHEV prototypes. Powertrain parameters are calculated according to the dynamicrequirements．The series thermostat control strategy has been used because the fuel converter operatesat the most efficient speed and torque level. The fuel converter turns on if the SOC is belowthe low limit, cs_lo_soc. The fuel converter remains on until the SOC reaches the high limit,cs_hi_soc, if its previous state was on. After reaching the high limit, it turns off.The simulation results show that the energy distribution strategy can perform features ofa PHEV．Powertrain parameters can meet the dynamic requirements．In the end，conclusions and new points in the project are summarized and the researchin the next step is also proposed．...