Page - 23 - in Emerging Technologies for Electric and Hybrid Vehicles

Energies 2017,10, 1217 Table8.Advantagesanddisadvantagesofdifferentequalizer types.Data from[46–52]. EqualizerType Advantage Disadvantage Resistive • Cheapest,widelyutilizedfor laptopbatteries • Inherentheatingproblem • Lowequalizingcurrent (300–500)mA • Onlyusable in the last stagesofcharging andflotation • Efficiency isalmost0% • Allequalizingcurrent transforms intoheat forEVapplication, therefore not recommended Capacitive • Bettercurrentcapabilities than resistiveequalizers • Nocontrol issue • Simple implementation • Unable tocontrol inrushcurrent • Potentiallyharmfulcurrent ripplescanflow forbigcellvoltagedifferences • Cannotprovideanyrequiredvoltage differencewhich isessential for SOCequalization Basic Inductive • Relativelysimple • Capableof transportinghigh amountofenergy • Canhandlecomplexcontrol schemes likevoltagedifference controlandcurrent limitation • Cancompensate for internal resistanceofcells • Increasedequalizingcurrent • Notdependentoncellvoltage • Requiresadditionalcomponents toprevent ripplecurrents • Needs twoswitches inadditiontodrivers andcontrols ineachcell • Currentdistribution ishighlyconcentrated inneighboringcellsbecauseof switching loss CukInductive • Hasall theadvantagesof inductiveequalizres • Canaccommodatecomplex controlandwithstand highcurrent • Additionalcostofhighervoltageand current ratedswitches,powercapacitors • Subjectedto losscausedbyseriescapacitor • Alittle lessefficient thantypical inductiveequalizers • Facesproblemsduringdistributing equalizingcurrentsallover thecell string • Mayneedadditionalprocessingpower Transformer basedInductive • Theoreticallypermitsproper currentdistribution inall cells withoutadditioncontrolor loss • Complex transformerwithmultiple secondary,which isverymuchchallenging tomassproduce • NotanoptionforEVpacks • Cannothandlecomplexcontrolalgorithms Multiple transformer basedInductive • Separate transformersareused whichareeasier for massproduction • Stilldifficult tobuildwithcommercial inductorswithout facingvoltageand current imbalance Table 9. Comparison of equalizers; a ↑ sign indicates an advantagewhereas the ↓ signs indicate drawbacks.Adaptedfrom[46]. EqualizerType EqualizerCurrent Current Distribution Current Control Current Ripple Manufacture Cost Control Resistive ↓↓ N/A ↑ ↑↑↑ ↑↑↑ ↑↑↑ ↑↑↑ Capacitive ↓ ↑ ↓↓ ↓↓ ↑↑ ↑↑ ↑↑ Basic Inductive ↑↑ ↑ ↑ ↑↑ ↑ ↓ ↓ Cuk ↑↑ ↑ ↑ ↑↑↑ ↓ ↓↓ ↓ Transformer ↑ ↑↑↑ ↓↓ ↓↓ ↓↓ ↓↓ ↑↑ 23