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Title: Modular Soft-Switching Converters for Motor Drive Applications
Committee:
Dr. Divan, Advisor
Dr. Habetler, Chair
Dr. Saeedifard
Abstract:
The objective of the proposed research is to develop new power electronic converters for low-voltage variable frequency motor drives in industrial applications and electric vehicle drivetrains. For economical and simplicity reasons, and owing to the absence of viable alternatives, the hard-switched two-level PWM voltage source inverter introduced over 30 years ago has become the industry standard for low-voltage motor drive applications, with ratings up to 690 Vrms and 3 MW. Yet, this topology suffers from a number of well-known challenges including high-frequency switching output voltages leading to electromagnetic interference (EMI) and common-mode voltage issues, inherent susceptibility to short circuit currents, low efficiencies under light-load conditions, and difficult parallel connection of multiple units limiting the system modularity. Numerous peripherals, complex and ruggedized semiconductor and machine designs, and advanced control strategies were developed over the years to mitigate these intrinsic topology challenges, adding cost and complexity to the drive systems and restricting the achievable power density. With the advent of wide bandgap power semiconductors capable of ultra-fast switching, and the commercial availability of such devices at increasing current and voltage ratings, these mitigation techniques become obsolete and another, presumably lengthy, research cycle towards higher-performance drives leveraging these new devices is required. Instead, new modular soft-switching current source converters are proposed in this research to develop the next-generation of high-performance motor drives, for industrial applications and electric vehicles, and address the main limitations of the existing voltage-sourced technology while fully leveraging the newest wide bandgap devices without added complexity.
