Seite - 227 - in Emerging Technologies for Electric and Hybrid Vehicles

Energies 2016,9, 410 VQ1,max “VQ3,max “VQ4,max “ VH2 (14) VQ2,max “VH (15) 3.3. InductorCurrentRipple The studiedBDCcan operate not only in charge state but also in discharge state. Thus, the inductorcanbecalculated ineitherchargeordischargestate.AccordingtoEquations (1)–(5), the total ripplecurrentof the inductorof thestudiedBDCinchargestatecanbeexpressedas: ΔiLt|charge “ VHTsw Ls p0.5´DdqDd (16) Similarly, indischargestate,accordingtoEquations(6)–(10), thetotalripplecurrentoftheinductor of thestudiedBDCindischargestatecanbeexpressedas: ΔiLt|discharge “ VHTsw Ls pDb´0.5qp1´Dbq (17) Figure12showsthenormalizedripplecurrentof the inductorof thestudiedBDC, the traditional BDC[18],andpreviousBDCsin[22,23],where the inductorandtheswitchingfrequencyof these three BDCsareequal, respectively. Theripplecurrentof the traditionalBDCat50%dutycycle isnormalized asone. Figure 12. Comparison of the normalized ripple current of the inductor among the studiedBDC, theconverters introducedin[18,22,23]. It canbeseenthat fromFigure12, themaximumripplecurrentof the inductorofstudiedBDC is only one-fourth of that of a traditional BDC.On the other and, if the ripple currents are equal, the inductor of the studiedBDC is only one-fourth of that of traditional BDC [18], whichmeans that thestudiedBDChasabetterdynamic response. FromFigure12, the ripple currentof studied BDCissmaller thanthatof theconverter in [22],underareasonablerangeof35%~65%dutycycles. Furthermore, theripplecurrentof thepreviousBDCproposedin[23] ishigher thanthatof theone proposedin this study,underareasonablerangeof30%~70%dutycycles. 227