Doctor of Philosophy, University of Akron, 2022, Electrical Engineering

Power density and performance improvement of the dual three-phase permanent magnet synchronous machine (DTP-PMSM) through control and design approaches are explored in this thesis. Power density improvements are found by reducing the number of dc-link capacitors, which is a crucial part of a drive system. While dc-link current ripples are reduced, control of the system is important to maintain the reduced harmonic distortion of the phase currents. Moreover, the design of the electric machine plays an important role in improving the power density and the performance of the drive system. As a result, multi-dimensional control and design approaches are explored in this dissertation to improve the performance of the power density of the DTP-PMSM drive system. A novel dynamic interleaving strategy is proposed to reduce the dc-link ripple of the inverter system. With the reduction of the dc-link ripple, the dc-link capacitor requirement of the drive system is reduced, which increases the power density of the drive system. While the conventional interleaving strategies use a constant interleaving angle, the proposed strategy dynamically varies the interleaving angle. The proposed strategy does not require any additional hardware system and can be applied to dual three-phase motor drives using any of the discontinuous pulse width modulation (DPWM) methods. The performance of the proposed strategy is compared with the control techniques using either constant interleaving or no interleaving methods. The performance of the proposed method is verified through analytical, simulation, and experimental results. A dual predictive current control method is proposed to improve the performance of the drive system. Through the proposed method, the number of vector evaluations is reduced, and the computational burden of the control system is reduced. A co-simulation platform, as well as the experimental dyno setup, were used to validate the performance of the proposed method. Ten (open full item for complete abstract)

Committee: Dr. Yilmaz Sozer (Advisor); Dr. Malik E. Elbuluk (Committee Member); Dr. J. Alexis De Abreu Garcia (Committee Member); Dr. D. Dane Quinn (Committee Member); Dr. Kevin Kreider (Committee Member) Subjects: Electrical Engineering; Electromagnetics

Doctor of Philosophy, University of Akron, 2021, Electrical Engineering

Acoustic noise and vibration prediction, mitigation, and performance optimization, in electric machines, are studied in this dissertation. First, vibration prediction enhancement in electric machines through frequency-dependent damping characterization is proposed in this dissertation. Different methods of mass and stiffness-dependent Rayleigh damping coefficient calculation are studied to identify the best damping estimation strategy. The proposed damping estimation strategy is used to predict the vibration spectrums of two 12-slot 10-pole (12s10p) permanent magnet synchronous machine (PMSM) designs and predicted vibration spectrums are experimentally validated through run-up tests of two prototypes. Moreover, to eliminate the dependency of the damping estimation strategy on the availability of a prototype, a damping coefficient prediction methodology is proposed. The proposed prediction methodology is experimentally validated using a third 12s10p PMSM prototype. Secondly, a lumped unit response-based sensitivity analysis procedure is introduced, which isolates electromagnetic and structural impacts brought by variation of different design parameters in an electric machine. The lumped unit response strategy utilizes the frequency-dependent damping estimation method developed early in the dissertation. The impact of different generic design parameters and a structural feature on a range of output quantities are studied in detail for a 12s10p PMSM. Analysis reveals that on a 12s10p PMSM, slot opening has a very high impact on the dominant airgap force component. A multi-level non-linear regression model-based optimization strategy is introduced considering electromagnetic and structural design objectives and constraints following the sensitivity analysis. A 12s10p PMSM prototype is tested to validate the FEA simulations used during the optimization process. Finally, the lumped unit response-based vibration prediction methodology devel (open full item for complete abstract)

Committee: Dr. Yilmaz Sozer (Advisor); Dr. Malik E. Elbuluk (Committee Member); Dr. J. Alexis De Abreu Garcia (Committee Member); Dr. D. Dane Quinn (Committee Member); Dr. Kevin Kreider (Committee Member) Subjects: Automotive Engineering; Electrical Engineering; Electromagnetics; Electromagnetism; Engineering; Mechanical Engineering; Technology

Doctor of Philosophy, The Ohio State University, 2020, Mechanical Engineering

Vehicle safety is one of the critical elements of modern automobile development. With increasing automation and complexity in safety-related electrical/electronic (E/E) systems, and given the functional safety standards adopted by the automotive industry, the evolution and introduction of electrified and automated vehicles had dramatically increased the need to guarantee unprecedented levels of safety and security in the automotive industry. The automotive industry has broadly and voluntarily adopted the functional safety standard ISO 26262 to address functional safety problems in the vehicle development process. A V-cycle software development process is a core element of this standard to ensure functional safety. This dissertation develops a model-based diagnostic methodology that is inspired by the ISO-26262 V-cycle to meet automotive functional safety requirements. Specifically, in the first phase, system requirements for diagnosis are determined by Hazard Analysis and Risk Assessment (HARA) and Failure Modes and Effect Analysis (FMEA). Following the development of system requirements, the second phase of the process is dedicated to modeling the physical subsystem and its fault modes. The implementation of these models using advanced simulation tools (MATLAB/Simulink and CarSim in this dissertation) permits quantification of the fault effects on system safety and performance. The next phase is dedicated to understanding the diagnosability of the system (given a sensor set), or the selection of a suitable sensor set to achieve the desired degree of diagnosability, using a graph-theoretic method known as structural analysis. By representing a system in directed-graph or incidence-matrix form, structural analysis allows the determination of analytical redundancy in the system and of the detectability and isolability of individual faults. Further, it provides a logical computation sequence for solving for system unknowns, by identifying analytical redundant relat (open full item for complete abstract)

Committee: Giorgio Rizzoni (Advisor); Manoj Srinivasan (Committee Member); Ran Dai (Committee Member); Qadeer Ahmed (Committee Member) Subjects: Automotive Engineering; Electrical Engineering; Mechanical Engineering

Doctor of Philosophy, Case Western Reserve University, 2020, EECS - Electrical Engineering

A motor drive system implementing direct torque control (DTC) and a resonant link inverter to drive a permanent magnet synchronous motor (PMSM) is designed, built, tested, and analyzed, and performance is compared to a standard drive system using field oriented control (FOC) and a hard switching inverter (HSI). Models and simulations of both systems are developed and presented. Simulations and design, build, and testing of the selected resonant inverter topology, the active clamped resonant link inverter (ACRLI), are discussed. A description of the specification and buildup of the motor lab for this effort, including the motor controller implementation, the motor under test, the test load, and support equipment is also provided. DTC performance improvement efforts are discussed, including the implementation of multiple flux and torque estimation schemes. Experimental results on the research system, the DTC-ACRLI, studying the effects of inverter and controller parameters on performance, are discussed. Comparisons of two key system performance metrics (system efficiency and noise) between the baseline FOC-HSI system and the research DTC-ACRLI system are presented. Conclusions, contributions of the work, and suggested areas for future work are also discussed.

Committee: Kenneth Loparo Ph.D. (Committee Chair); Cenk Cavusoglu Ph.D. (Committee Member); Vira Chankong Ph.D. (Committee Member); Wei Lin Ph.D. (Committee Member) Subjects: Electrical Engineering

Doctor of Engineering, Cleveland State University, 2017, Washkewicz College of Engineering

The key problem in control system design was the selection and processing of information. The first part was to collect some system dynamics offline or online in a cost-effective manner and use them in the controller design effectively. Next was to minimize the phase lag in the feedback loop to ensure best performance and stability. A systematic information-driven design strategy was discussed. A few key problems in permanent magnet synchronous motor control were taken in a case study: the current loop and decoupling, velocity loop with position feedback and position estimation at low speed. An active disturbance rejection based integrated current loop control solution was presented. Some implementation problems were also discussed: restructuring of active disturbance rejection control for implementation, scaling of extended state observer in fixed-point implementation and observer-based parameter estimation. The proposed methods were tested in simulation and hardware experiments.

Committee: Zhiqiang Gao Ph.D. (Advisor); Ana Stankovic Ph.D. (Committee Member); Lili Dong Ph.D. (Committee Member); Hanz Richter Ph.D. (Committee Member); Sally Shao Ph.D. (Committee Member); Hui Tan Ph.D. (Committee Member) Subjects: Electrical Engineering; Systems Design

Doctor of Philosophy, The Ohio State University, 2016, Mechanical Engineering

Functional safety is an important element for future automobile development. To ensure functional safety, the automotive industry has adopted a functional safety standard - ISO26262 to standardize the design and implementation of functional safety requirements during different phases of an automobile's safety lifecycle. This dissertation proposes a model-based approach for achieving some aspects of automotive functional safety through model-based diagnosis. After using hazard analysis and risk assessment to define functional safety and diagnostic requirements, the method developed in this dissertation consists of a systematic approach for the design of diagnostic strategies that leads to implementation of the algorithms to satisfy the functional safety goals. In particular, this dissertation exploits the mathematical tools of structural analysis to detect and isolate various faults in a complex system. The advantage of using the structural analysis approach for fault detection and isolation lies in the ability to efficiently analyze the analytic redundancy of a system and systematically design structured residual generators to satisfy given diagnostic requirements. The effectiveness of this approach is demonstrated by designing diagnostic algorithms for sensor fault detection and isolation in a permanent magnet synchronous machine electric drive system for an electrified powertrain. The diagnostic strategy is proven to be effective in detecting and isolating various sensor faults in a PMSM drive system. The structural analysis approach systematically generates the options of designing residual generators, whose number may be quit large in a complex system. This dissertation also introduces a novel approach for selecting residual generators to downsize the solution sets, considering the feasibility, diagnosability and computational complexity of residual generators, as well as their sensitivity and robustness. Based on these criteria, the optimal diagnostic test c (open full item for complete abstract)

Committee: Giorgio Rizzoni (Advisor); Vadim Utkin (Committee Member); Vishnu Sundaresan (Committee Member); David Hoelzle (Committee Member); Bilin Aksun-Guvenc (Committee Member) Subjects: Automotive Engineering; Electrical Engineering; Mechanical Engineering

Doctor of Philosophy, The Ohio State University, 2016, Electrical and Computer Engineering

The use of soft and hard magnetic materials in the construction of electric machines has become a common practice. However, demand for machines with higher power density and efficiency sets new challenges; new machines require non-conventional geometries, materials with higher energy densities, higher operating temperatures and reliable mechanisms of control. The Permanent Magnet Synchronous Machine (PMSM) is one of the key enabling technologies that have been subject of investigation in the past few decades because it can outperform other types of electric machines in a broad range of applications. In the manufacturing of high power density PMSMs, even small manufacturing variations can impact heavily on their performance. The tolerances and imperfections lead to physical machine asymmetries, and this work deals with the modeling and analysis of these asymmetries. It is noteworthy that asymmetries can also be introduced in the machine intentionally to enhance the functionality in certain cases. By means of electromagnetic field theory, analytic models have been developed in this study; Also, numerical analysis on the basis of Finite Element Method (FEM) have been extensively used throughout this work with the aim to validate the results and further investigate the non-linear nature of materials. Prototypes of Surface-Mounted Permanent Magnet (SPM) machines, Interior Permanent Magnet (IPM) machines and Synchronous Reluctance Machines assisted Permanent Magnets (PMaSynRM) were built and tested to verify the validity of the proposed models under loaded and unloaded conditions. The results provided by the analytic models were considerably more time-efficient without compromising accuracy when compared to those of FE-based models, even when the geometries do not match perfectly owing to the limitations of solving the model in polar coordinates. %Discrepancies were found only when the machine goes beyond the linear region due to the assumption of infinite permeabilit (open full item for complete abstract)

Committee: Longya Xu (Advisor); Vadim Utkin (Committee Member); Mahesh Illindala (Committee Member) Subjects: Electrical Engineering

Master of Science (M.S.), University of Dayton, 2013, Electrical Engineering

The main objective of this thesis is to track a reference speed being applied to permanent magnet synchronous motor (PMSM). As it known, these types of motors depend on a 3-phase time-dependent voltage source (3-Phase AC supply voltages) that generates a magnetic flux in the air-gap of the machine. This generated magnetic flux interacts with the permanent magnetic flux on the rotor, to generate the required torque. The mathematical model of this motor is a non-linear time-varying system. To apply different control techniques, we transform this model to an equivalent linear time-invariant system. These transformations not only yield a linear time-varying model, but also, reduce the number of states in the model. Classical control techniques, such as PI control, can provide a speed tracking of this type of motors with some limitations. In general, the performance of the motor is limited in term of the range of speed and the range of applied load torque. Also, the performance is affected by parameter variations or the high frequency, un-modeled states. In this project, a sliding-mode controller is used due to its insensitivity to the variations of the parameters. These types of controllers employ sliding surface, passing through the origin on the system trajectories plane. Once the system trajectory hits the sliding surface, they remain on it, and exhibiting stable operation. The conventional sliding surfaces are gained by a fixed constant which makes the control input exhibit a chattering phenomena. The proposed gain in this project is a smooth function, depending on the surface value to eliminate the chattering phenomena (soft switching mechanism). The primary problem with this design is the steady state error when a full-load torque is applied motor. This is overcome by designing an observer to estimate the load torque.

Committee: Malcolm Daniels Ph.D. (Advisor); Raul Ordonez Ph.D. (Committee Member); John Loomis Ph.D. (Committee Member) Subjects: Electrical Engineering

Master of Science, University of Akron, 2013, Electrical Engineering

A novel speed control algorithm for permanent magnet synchronous motors (PMSM) which maximizes efficiency without requiring phase current sensors is proposed in this thesis. The algorithm is described for a buried magnet type interior permanent magnet (IPM) motor but it is also suitable for surface mount type motors. The suggested algorithm implements maximum torque per ampere (MTPA) control in a PMSM drive system, considering the parameter variations due to magnetic saturation and change in temperature. Only DC link current, DC bus voltage and mechanical speed are used in the implementation of the algorithm, eliminating the requirement for three phase current measurements. The scheme employs an online search algorithm with an initial condition computed from a-priori system information. Hybridization of the search algorithm with pre-computed control coefficients ensures robustness against parameter variations while maintaining good dynamic performance. The proposed scheme is implemented on a 1.5 HP IPM and the validity of the approach is justified through experimental and simulation results.

Committee: Yilmaz Sozer Dr. (Advisor); Malik Elbuluk Dr. (Committee Member); Tom Hartley Dr. (Committee Member) Subjects: Electrical Engineering; Energy; Engineering

Master of Science in Electrical Engineering, Cleveland State University, 2013, Fenn College of Engineering

Permanent magnet synchronous motor (PMSM) is a popular electric machine in industry for its small volume, high electromagnetic torque, high reliability and low cost. It is broadly used in automobiles and aircrafts. However, PMSM has its inherent problems of nonlinearity and coupling, which are challenges for control systems design. In addition, the external disturbances such as load variation and noises could degrade the systems performance. Both sliding mode control (SMC) and active disturbance rejection control (ADRC) are robust against disturbances. They can also compensate the nonlinearity and couplings of the PMSM. Therefore, in this thesis, we apply both SMC and ADRC to a PMSM speed system. Our control goal is to drive the speed outputs of the PMSM speed system to reference signals in the presences of nonlinearity, disturbance, and parameter variations. Simulation results verify the effectiveness of SMC and ADRC on the speed control for PMSM systems in spite of the presences of external disturbance and internal system uncertainties.

Committee: Lili Dong PhD (Committee Chair); Eugenio Villaseca PhD (Committee Member); Siu-Tung Yau PhD (Committee Member) Subjects: Electrical Engineering

Doctor of Philosophy, The Ohio State University, 2007, Electrical Engineering

Permanent-magnet-synchronous-machine (PMSM) drives have been increasingly applied in a variety of industrial applications which require fast dynamic response and accurate control over wide speed ranges. Two control techniques are proposed in this dissertation for PMSM drives, namely flux-weakening control incorporating speed regulation and sliding mode observer with feedback of equivalent control. The research objectives are to extend the operating speed range of the PMSM drive system and improve its control robustness and adaptability to variations of operating conditions as well as dynamic performance. First, a robust flux-weakening control scheme is studied. With a novel current control strategy, the demagnetizing stator current required for the flux-weakening operation can be automatically generated based on the inherent cross-coupling effects in PMSM between its direct-axis and quadrature-axis current in the synchronous reference frame. The proposed control scheme is able to achieve both flux-weakening control and speed regulation simultaneously by using only one speed/flux-weakening controller without the knowledge of accurate machine parameters and dc bus voltage of power inverter. Moreover, no saturation of current regulators occurs under any load conditions, resulting in control robustness in the flux-weakening region. Secondly, a sliding mode observer is developed for estimating rotor position of PMSM without saliency in the implementation of position-sensorless vector control. A concept of feedback of equivalent control is applied to extend the operating range of sliding mode observer and improve its angle-estimation performance. Compared to conventional sliding mode observers, the proposed one features the flexibility to design parameters of sliding mode observer operating in a wide speed range. The estimation error of rotor position can be reduced by properly selecting the feedback gain of equivalent control. In addition, a flux-based sliding mode obser (open full item for complete abstract)

Committee: Longya Xu (Advisor) Subjects:

Doctor of Philosophy, University of Akron, 2009, Electrical Engineering

This dissertation presents a methodology for designing low noise small permanent magnet synchronous motor (PMSM) drives by addressing the issues of cogging torque, torque ripple, acoustic noise and vibration. The methodology incorporates several pole shaping and magnet skew schemes in different motor topologies with similar envelop dimensions and output characteristics intended for an automotive application. The developed methodology is verified with finite element analysis (FEA) and experiments. A comprehensive design methodology has been developed for obtaining the analytical design of the machine for a given set of output characteristics. Using the FEA, the effects of various magnet shapes and skew on the machine performances (e.g. cogging torque, torque ripple etc.) have been analyzed. The FEA and experimental results show that for certain magnet designs and configurations the skewing does not necessarily reduce the ripple in the electromagnetic torque, but may cause it to increase. An analytical model to predict radial vibration due to magnetic radial pressure on the motor structure has also been developed. This model is used for predicting the noise power level for several motor topologies designed for similar powe level applications. The predicted noise levels are utilized to develop guidelines for selecting motor configurations, internal dimensions and winding types for a low-noise PMSM. The selection of low-noise PMSM is not a straightforward one; rather it is a compromise between torque harmonics and radial vibration of the machines. Some PMSM configurations with less radial vibration might have seen to posses excessive torque ripples and thereby violating the other requirements for the motor to be less noisy. Experiments are conducted to record the torque ripple variation for different magnet shapes and skew in order to validate the results of FE models. The experimental results have successfully correlated with the FE computations.

Committee: Iqbal Husain (Advisor) Subjects: Electrical Engineering

Master of Science, University of Akron, 2006, Electrical Engineering

Permanent Magnet Synchronous Machines (PMSM) are being increasingly used because of their advantages over other machines, which include compactness, high efficiency, and well developed drives. The control of sinusoidal PMSM is usually done in the synchronous frame, which requires the knowledge of the rotor position. The sensing of the position is done through optical encoders or synchro-resolvers that increases the cost of the drive and decreases the overall reliability of the system. The substitution of the position sensors by advanced algorithms embedded in the controls hardware and software has been investigated for the last couple of decades. This thesis presents a review of the most common position estimators, and a comparison has been made to determine which one is the best candidate for implementation in industrial applications. The sensorless method relying on back-EMF estimation has been found to be the most promising, and hence, is further investigated in detail. The sensorless drive is studied through simulations, from low speed to very high speed at different torque levels. Then, very low speed and starting of the PMSM is studied, and a non-intrusive method to select the direction of rotation is proposed, given some assumptions about the load. The sensorless starting and operation have been verified experimentally using a digital signal processor implementation. A solution to achieve speed reversal and four-quadrant operation has also been proposed. Finally, a sensitivity analysis of the impact of the position estimation error on the machine torque is presented. The implementation and associated analysis prove that the selected algorithm is highly suitable for position sensorless PMSM drives coupled to passive loads, with a decrease of less than 0.8% in the output torque compared to drives using a position encoder.

Committee: Iqbal Husain (Advisor) Subjects: