Hybrid Electric Vehicles, 2nd Edition

13EV and PHEV Battery Charger Design¹

In this chapter, efficiency oriented design considerations are discussed in detail on the operation mode analysis of the LLC converter including the characteristics of charging profiles. The mode boundaries and distribution are obtained from the precise time domain model. The operation modes featuring both‐side soft‐switching capability are identified to design the operating trace of the charging process. Then the design constraints for achieving soft‐switching with the load varying from zero up to the maximum are discussed. Finally, a charging trajectory design methodology is proposed and validated through experiments on a prototype converting 390 V from the DC power source to the battery emulator in the range of 250–450 V at 6.6 kW with a peak efficiency of 97.96%.

13.1 Introduction

In today’s PHEVs and EVs, an onboard charger is installed to charge the high power lithium‐ion battery pack through the utility power [1–6]. According to a thorough survey, the most common EV/PHEV charger architecture consists of a boost type AC–DC converter for active power factor correction (PFC) and an isolated DC–DC converter as the second stage, as shown in Figure 13.1(a) [7–10]. The characteristic of this type of charger is mainly dependent on the DC–DC stage, since the output voltage and current are regulated in this stage. Therefore, an efficient and compact isolated DC–DC converter is one of the most important components for EV and PHEV battery ...