Exploring Multiphase Inverters for Open-Winding Machine Drives
Juris Arrozy defended his PhD thesis at the Department of Electrical Engineering on December 18th.
For his PhD research Juris Arrozy provided a framework for the comparative analysis of six-phase full-bridge inverter topologies for six-phase open-winding drive.
Arrozy investigated potential dc/ac inverter topologies for future electric propulsion applications. Attention to reliability-related issues such as fault tolerance and lifetime-related parameters are emphasized. The study shows that one inverter topology may be better for one application but not necessarily other applications. The comparative evaluation performed in this thesis shed some new lights on the consideration of future electric propulsion technologies research and development.
Study on multiphase inverters
The research is concerned with the study of multiphase inverters for six-phase open-winding machines. Several aspects of the inverters such as topologies, fault-tolerant control, modulation techniques, input current ripple, and common-mode voltage & current are studied. Three topologies, i.e. single supply six-phase full-bridge inverters, double supply six-phase full-bridge inverters, and series connectable modular full-bridge inverters are chosen. For the modulation techniques, bipolar modulation, unipolar modulation, level-shifted PWM, and phase-shifted PWM are chosen.
Influence of topology and modulation
It is shown that the selection of topology and modulation techniques influence the performance of the drive system. The choice of topology affects the post-fault torque, switch utilization ratio, and switch thermal stress whereas the choice of modulation technique affects the value of input current ripple and common-mode current.
Additionally, analytical equations that take into account the influence of dead-time on the input current ripple are proposed. The equations are verified in three-phase and six-phase full-bridge inverters cases.
Title of PhD thesis: Exploring Multiphase Inverters for Open-Winding Machine Drives - Topologies, Fault Tolerance, and Impacts of Modulation Techniques. Supervisors: Dr. Henk Huisman, and Dr. Esin Ilhan Caarls.