Fahīmī, Bābak
Permanent URI for this collectionhttps://hdl.handle.net/10735.1/6977
Bābak Fahīmī holds the Distinguished Chair in Engineering and is a Professor of Electrical Engineering. Dr. Fahīmī also serves as the founder and head of the Renewable Energy and Vehicular Technology Laboratory and is a Fellow of IEEE. His research interests include:
- Microscopic and Macroscopic Energy Conversion,
- Power Electronic Systems,
- Modeling and Stability Assessment of Multiconverter Systems
- Adjustable-Speed Motor Drives
- Transportation Electrification
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Recent Submissions
Item Structural Analysis of Induction Machine and Switched Reluctance Machine(Taylor & Francis Inc, 2019-02-23) Maharjan, Lizon; Wang, Shiliang; Fahīmī, Bābak; 0000-0001-8398-126X (Fahīmī, B); Maharjan, Lizon; Wang, Shiliang; Fahīmī, BābakHere we present a comprehensive analysis of structural performance of Induction Machine (IM) and Switched Reluctance Machine (SRM) rotors under different operational conditions. Electric machines are susceptible to forces of diverse origins. In addition to traditionally considered magnetic and centrifugal forces, this article discusses independent and inclusive effects of thermal expansion and shaft attachment techniques on structural integrity of the machines. A comparative analysis of structural performance of IMs and SRMs has also been performed, under a range of scenarios, to facilitate application-specific machine selection from a structural perspective.Item Electrothermal Modeling of Lithium-Ion Batteries for Electric Vehicles(Institute of Electrical and Electronics Engineers Inc, 2018-11-07) Yang, Zhuo; Patil, Devendra; Fahimi, Babak; 0000-0002-5005-2023 (Yang, Z); Yang, Zhuo; Patil, Devendra; Fahimi, BabakThe performance of lithium-ion batteries is contingent on the operational temperature and applied current rate. Especially in electric vehicle application, repeated heavy-duty drive cycles impose intense thermal stress on batteries, resulting in safety concerns. This paper explains the electrochemistry within the battery and analyzes the dependence of battery internal parameters on temperature and current rate based on their electrochemical nature. In addition, this interdependence is used in the equivalent circuit model to predict the battery behavior under different drive cycles. Finally, the behavior under different drive cycles is analyzed to improve the battery performance in electric vehicles.Item Active Cancellation of Vibration in Switched Reluctance Motor Using Mechanical Impulse Response Method(Institute of Electrical and Electronics Engineers Inc., 2019-05-13) Kimpara, M. L. M.; Wang, S.; Caicedo-Narvaez, Carlos Andres; Chen, Tianyu; Pinto, J.; Borges da Silva, L. E.; Moallem, M.; Fahīmī, Bābak; 0000-0001-8398-126X (Fahīmī, B); 0000-0002-1605-6944 (Cacedo-Narvaez, C); 0000-0001-7704-0770 (Chen, T); 56099860 (Fahīmī, B); Caicedo-Narvaez, Carlos Andres; Chen, Tianyu; Fahīmī, BābakVibration and acoustic noise are considered as major factors preventing the widespread use of switched reluctance motor (SRM) drives in industrial and commercial applications. In this paper, a new active vibration cancellation (AVC) strategy for radial vibration is proposed based on the optimal current switching instants. The mechanical impulse response method has been used to estimate the radial vibration of the stator and an optimization routine was developed to define the optimal instants for phase current switching in such a way that the resulting vibration would cancel the vibration caused by prior switching. Experimental verification was conducted on an 8/6 SRM and the results show significant reduction in the stator radial vibration which in turn contributes to reduction of acoustic noise.Item Induced Chaos in Speed Controlled Switched Reluctance Motor Drive(Institute of Electrical and Electronics Engineers Inc., 2019-03) Li, Sen; Fahimi, Babak; Li, Sen; Fahimi, BabakIn this paper the occurrence of chaos in the hysteresis-controlled switched reluctance motor (SRM) drive under phase current saturation is examined. An 8/6 pole 4-phase SRM is used as the model for this study. To gain insight into this phenomenon, the analytical modelling of the SR drive system is derived and triggering condition for chaotic behaviors is discussed. The simulation and experimental analyses are conducted to uncover the underlying pattern of chaotic motion within this type of motor drive system. ©2019 IEEE.Item A Coil Detection System for Dynamic Wireless Charging of Electric Vehicle(Institute of Electrical and Electronics Engineers Inc.) Patil, Devendra; Miller, J.; Fahimi, Babak; Balsara, Poras T.; Galigerkere, V.; Patil, Devendra; Fahimi, Babak; Balsara, Poras T.Application of wireless power transfer while EV is in motion can significantly reduce the battery storage capacity. A major challenge in implementation of dynamic wireless power transfer (DWPT) is automatic detection of EV to avoid loss in efficiency and alleviate any safety concerns. This paper proposes a novel coil detection method for segmented DWPT. Detection of the EV ahead of its arrival will initiate energizing of the transmitter buried inside the road to enable just-in-time transfer of power. At low speeds, communication can be a reliable method to power up the transmitter coil. However, at high speeds on highways, communication latency time for the detection of an EV is long and hence impractical. This paper proposes a low cost and low power EV detection system based on a novel orthogonal coil arrangement to detect EVs traveling at high speeds. The proposed detection system was tested on a laboratory scale prototype for verification purpose. For high speed verification, simulation in PLECS was conducted to test the functionality of the proposed system. ©2019 IEEEItem Optimization of Air-Gap Profile in Interior Permanent-Magnet Synchronous Motors for Torque Ripple Mitigation(Institute of Electrical and Electronics Engineers Inc.) Liang, Jingchen; Parsapour, Amir; Yang, Zhuo; Caicedo-Narvaez, Carlos; Moallem, M.; Fahimi, Babak; Liang, Jingchen; Parsapour, Amir; Yang, Zhuo; Caicedo-Narvaez, Carlos; Fahimi, BabakInterior permanent-magnet synchronous motors (IPMSMs) have been widely used due to their high-efficiency and high-power densities. Minimization of torque pulsation resulting in vibration and acoustic noise is one of the important design considerations for IPMSMs. In this paper, a grid on/off search method for the rotor profile is proposed to mitigate torque pulsation. Selection of the rotor profile is due to the fact that air gap is the most sensitive parameter in electric machines wherein changes in flux densities can cause substantial differences in the distribution of forces. A layer comprised 20 partitions with a 0.1 mm thickness and 3° wide grids have been introduced to the rotor surface for each pole, and the possible geometries have been analyzed using the finite-element method in ANSYS Maxwell. An optimal design was found that has the lowest torque ripple with a higher average torque compared to the original design. Genetic algorithm has also been applied to the method to automate the coupling between Maxwell and MATLAB, thereby saving the simulation time. Complete structural analysis has been done for both of the original and optimal designs to verify the superiority and feasibility of the proposed design. ©2019 IEEE.Item Simultaneous Optimization of Geometry and Firing Angles for In-Wheel Switched Reluctance Motor Drive(Institute of Electrical and Electronics Engineers Inc.) Anvari, B.; Toliyat, H. A.; Fahimi, Babak; Fahimi, BabakInterests in using rare-earth free motors such as switched reluctance motors (SRMs) for electric and hybrid electric vehicles continue to gain popularity, owing to their low cost and robustness. Optimal design of an SRM, to meet specific characteristics for an application, should involve simultaneous optimization of the motor geometry and control in order to achieve the highest performance with the lowest cost. This paper presents a constrained multiobjective optimization framework for design and control of an SRM based on a nondominated sorting genetic algorithm II. The proposed methodology optimizes SRM operation for high volume traction applications by considering multiple criteria including efficiency, average torque, and torque ripple. Several constraints are defined by the considered application, such as the motor stack length, outer diameter, minimum operating power, minimum desired efficiency, rated speed, rated current, and supply voltage. The outcome of this optimization includes an optimal geometry, outlining variables such as air gap length, rotor inner diameter, stator pole arc angle, rotor pole arc angle, rotor back iron, stator pole height, and stator inner diameter as well as optimal turn-on and turn-off firing angles. Then the machine is manufactured according to the obtained optimal specifications. Comprehensive finite-element analysis and experimental results are provided to validate the theoretical findings. © 2017 IEEE.Item Online Estimation of Capacity Fade and Power Fade of Lithium-Ion Batteries Based on Input-Output Response Technique(Institute of Electrical and Electronics Engineers Inc.) Yang, Zhuo; Patil, Devendra; Fahimi, Babak; 0000-0002-5005-2023 (Yang, Z); 0000-0001-9271-4227 (Devendra, P); Yang, Zhuo; Patil, Devendra; Fahimi, BabakLithium-ion batteries present promising potential in electrified transportation due to their high-power density and long cycle life. However, during the life cycle, lithium-ion batteries are subject to degrading capacity and power. This paper presents an online estimation approach of capacity fade and analyzes the power fade of lithium-ion batteries using an input-output response method. By processing the waveforms of response, one can predict the actual capacity and internal resistance which characterizes the battery health. In the end, the proposed method is validated experimentally. This provides an online estimation tool to describe the aging effects of batteries. Finally, this analysis suggests an optimal operating depth of discharge considering the battery efficiency. © 2015 IEEE.