Date of Award
2024
Publication Type
Dissertation
Degree Name
Ph.D.
Department
Electrical and Computer Engineering
Supervisor
Lakshmi Iyer
Supervisor
Narayan Kar
Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 4.0 International License.
Abstract
The industry transition to electrification is demanding developments to address the technological gaps and targets set for performance enhancement and cost reduction of electric vehicles to enable mass adoption by consumers. The inverter in the electric drive system is a critical component used to control the powertrain and achieve high performance; it is therefore the focus of this thesis. To enhance the performance and cost of the electric drive system, state–of–the–art technologies such as wide bandgap semiconductor devices, novel component and vehicle–level control techniques, and soft–switching architectures are investigated. First, torque–speed performance targets of electric vehicles are determined using vehicle dynamics modeling with standardized drive cycles. The electric powertrain system is introduced and an electric motor plant model is derived with electric motor controls to model the performance of the inverter within the powertrain system. An improved wide bandgap, gallium nitride based thermal and electrical inverter model is derived, experimentally calibrated, and validated against testbench measurements. Novel control strategies regarding deadtime minimization and variable switching frequency are proposed to enhance inverter efficiency through the reduction of switching losses. Additionally, the variable switching frequency control technique is leveraged towards cost reduction of the DC–link capacitor while maintaining high drive cycle efficiency. Additionally, a hill–hold control strategy is proposed that minimally displaces the vehicle’s position to achieve a reduction of overall inverter temperature which reduces the need for derating and extends the torque capability of the powertrain in hill–hold. Furthermore, an innovative auxiliary resonant commutated pole soft–switching inverter architecture is proposed to minimize inverter switching losses. A design framework and modeling approach is introduced, and the inverter performance is benchmarked against conventional two–level inverters incorporating wide bandgap semiconductor technology. The effect of passive component variations is analyzed to assess the reliability, control complexity, and impact on performance of the architecture while considering manufacturing tolerances and temperature variations that could exist in a practical implementation of the technology. Finally, a novel pulse and glide vehicle–level control strategy is proposed that modulates the torque output of the powertrain to reduce powertrain losses. The method transitions the vehicle’s powertrain between moments of acceleration and coasting, in which the powertrain is disabled to reduce inverter switching losses and electric motor core losses which reduces overall powertrain losses. The user discomfort resulting from the control strategy is assessed and a novel jerk limitation controller is proposed to constrain the user discomfort within acceptable limits. The recommendations for future work to further develop the concepts outlined in the thesis are summarized towards the end of the dissertation.
Recommended Citation
Korta, Philip, "Advanced Electric Drive System Design and Control for Electric Propulsion" (2024). Electronic Theses and Dissertations. 9624.
https://scholar.uwindsor.ca/etd/9624