To improve the energy utilization of the battery packs in EVs, battery-integrated modular multilevel converters (BI-MMCs) are introduced. Design optimization for BI-MMC with phase-shifted modulation (PSPWM) showed that submodule DC-link capacitors designed to bypass the switching frequency components result in minimum total losses. However, PSPWM has high semiconductor switching losses. An alternative modulation technique, nearest level control (NLC), characterized by low semiconductor switching frequency, is often preferred for MMCs with numerous submodules. The first contribution is a comparison of losses using PSPWM and NLC modulation techniques for 3-phase BI-MMCs. A single-phase 4-SM BI-MMC is selected as an experimental example for the comparison. The second contribution is investigating the impact of the size of DC-link capacitors on battery and capacitor losses for NLC. The analytical calculations for a single-phase 4-SM BI-MMC showed that the battery and capacitor losses are independent of the DC-link capacitor size. Furthermore, NLC has lower total losses but higher battery losses than PSPWM.
