Soft-switching current source inverter for next-generation electric vehicle drivetrains

Motor drives are a critical piece of equipment in electric vehicles, yet the existing and aging voltage source inverter topology used in most drivetrains suffers from well-known challenges and requires numerous mitigation techniques increasing system cost and complexity and limiting the power density. Although the technology has reached a commendable maturity level using silicon IGBT devices, leveraging the latest wide bandgap devices is proving to be extremely challenging. This paper proposes a novel soft-switching converter topology addressing these limitations and offers a new approach to developing the next generation of high-performance electric vehicle drivetrains. The minimal topology performs the required bi-directional DC-AC conversion in a single-stage structure and ensures zero-voltage switching of all power devices across the entire load range. Furthermore, the high-frequency operation reduces the size of the passive elements for a power-dense design, and leads to excellent converter dynamic with unique efficiency profiles. The fundamental operating principles are introduced in this paper and the concept is verified through simulation of a 25 kVA SSCSI drivetrain.