A Multi-Phase Segmented Drive Comprising Arrayed Flying Capacitor Multi-Level Modules

Recent activity in research surrounding electric vehicle propulsion has indicated that modular or segmented drives show promise for meeting the demanding performance and scalability targets set forth in industry road maps. Additionally, unconventional topologies, such as the flying capacitor multilevel topology (FCML), have demonstrated high-efficiency and high-specific-power—as well as reduction in output current distortion, dv/dt and filter size. This work highlights the technical challenges and performance benefits arising in the implementation of a segmented drive from an array of independent FCML inverter modules. Harmonic content in the ac phase legs and dc bus currents is analyzed and experimentally measured. Furthermore, a hierarchical control strategy with specific emphasis on the synchronization of both the carrier and fundamental across multiple modules is demonstrated. The work concludes with a demonstration of the paralleled, interleaved and multi-phase operation of a multi-module array, with conducted emissions measured on a CISPR-25 pre-compliance test fixture.