Modular switched-capacitor Dc-Dc converters tied with lithium-ion batteries for use in battery electric vehicles

This paper presents a modular switched-capacitor (SC) dc-dc converter based electric drive system for battery electric vehicles. In such a system, modularized lithium-ion battery cell tied MOSFET SC converters are used instead of the more conventional IGBT boost converter. Following the drive train architecture, the modeling approach for each electrical component, including the battery set, dc-dc and dc-ac converters, ac machines, and their control is discussed. Emphasis is given on state of the art lithium-ion battery models and SC converter design. System level performance is analyzed based on simulation results across drive cycles. Hardware including a three-cell lithium-ion battery tied SC converter module is built and tested. Application notes such as economic and spacing constraints are addressed.