This dissertation is concerned with the design of permanent magnet synchronous motors (PMSM) to operate at super-high speed with high efficiency. The designed and fabricated PMSM was successfully tested to run upto 210,000 rpm The designed PMSM has 2000 W shaft output power at 200,000 rpm and at the cryogenic temperature of 77 K. The test results showed the motor to have an efficiency reaching above 92%. This achieved efficiency indicated a significant improvement compared to commercial motors with similar ratings. This dissertation first discusses the basic concept of electrical machines. After that, the modeling of PMSM for dynamic simulation is provided. Particular design strategies have to be adopted for super-high speed applications since motor losses assume a key role in the motor drive performance limit. The considerations of the PMSM structure for cryogenic applications are also discussed. It is shown that slotless structure with multi-strand Litz-wire is favorable for super-high speeds and cryogenic applications. The design, simulation, and test of a single-sided axial flux pancake PMSM is presented. The advantages and disadvantages of this kind of structure are discussed, and further improvements are suggested and some have been verified by experiments. The methodologies of designing super high-speed motors are provided in details. Based on these methodologies, a super high-speed radial-flux PMSM was designed and fabricated. The designed PMSM meets our expectation and the tested results agree with the design specifications. 2-D and 3-D modeling of the complicated PMSM structure for the electromagnetic numerical simulations of motor performance and parameters such as phase inductors, core losses, rotor eddy current loss, torque, and induced electromotive force (back-EMF) are also presented in detail in this dissertation. Some mechanical issues such as thermal analysis, bearing pre-load, rotor stress analysis, and rotor dynamics analysis are also discussed. Different control schemes are presented and suitable control schemes for super high- speed PMSM are also discussed in detail.

<p> The analysis of stepping motors using linear models has been simplified through identifications of the constants. Though the existing nonlinear models assuming a smooth air-gap machine may, in some cases, yield a fairly close prediction of the characteristics of a stepping motor, the models do not represent the actual motors which are essentially salient-pole motors. A new salient-pole nonlinear model is introduced. The analysis of permanent-magnet stepping motors using the nonlinear models has been simplified by assuming constant current sources. Dynamic behaviors of a permanent -magnet stepping motor are shown by phase-plane plots and step by step transient response plots.</p> <p> Computer control of stepping motors in both open-loop and closed-loop is discussed. The open-loop control has been demonstrated to be successful and a closed-loop control system using light-sensors as feedback has been designed.</p> / Thesis / Master of Engineering (MEngr)

The growing demand of electrified light duty trucks, including sports utility vehicles (SUV) require high performance motors to surpass form their internal combustion engine counterparts. The Axial Flux Permanent Magnet (AFPM) Motor is expected to be one of the leading technologies to meet the demands of these industries due to its efficenct and high torque and power density. Designing a robust thermal management system for this motor is key to utilizing these performance benefits. To meet these demanding conditions, additive manufacturing is expected to play a critical role in enhancing performance. Additively manufactured hollow coil is a cooling strategy to extract heat directly from the hottest part of the motor, the stator. The following research assesses the viability of the design in a prototype motor. ANSYS CFX is used to characterize the pressure drop and flowrate, and a test setup is used to validate the results. The challenges associated with integrating the solution into a motor is highlighted as well as design issues during design development. Finally, the integration of a parallel hybrid SUV using an AFPM motor is documented and the challenges with integration into a vehicle is explained. / Thesis / Master in Advanced Studies (MAS)

A Thesis Submitted to the School of Graduate Studies in Partial Fulfillment of the Requirements for the Degree of Master of Applied Science in Mechanical Engineering / In the wake of the rising global demand for more electric transportation, aerospace electrification is becoming a highly active research area as commercial fully electric aircrafts are becoming a reality. The transportation electrification industry is challenged to develop powerful, safe, and compact-sized machines that can replace fossil fuel powered engines in aircrafts. Axial Flux Permanent Magnets (AFPM) machines are currently being intensively developed as a great candidate for this purpose due to their inherently higher power density compared to other machine electric machines topologies. The efforts of further increasing AFPM machines power density add more thermal challenges as intensive cooling is required at a relatively small machine package to avoid machine failure. One of the most concerning failure modes in these machines is power output reduction due to overheating of the rotor-mounted permanent magnets or even complete failure due to irreversible demagnetization. This research discusses the design process of an integrated rotor air cooling system for a 100 kW AFPM machine designed for an electric aircraft propulsion system. The embedded cooling system allows the rotor to be self-cooled at a sufficient cooling rate while minimizing the impact on machine efficiency due to windage power losses. The presented design process includes several stages of cooling enhancement including the addition and fine-tuning of rotor fan blades and rotor vents design. These enhancements are done by studying the air flow over the rotor surfaces in conjunction with heat transfer through Conjugate Heat Transfer (CHT) Computational Fluid Dynamics (CFD) analyses. In an initial study, different rotors with different combinations of rotor cooling features are studied and their thermal performance is compared. The results show that using rotor embedded fan blades in throughflow ventilated rotor geometry offers the best performance balance, achieving sufficient rotor cooling rate within a reasonable increase of windage power loss. A parametric study is performed to improve the rotor blade geometry for a higher ratio of heat transfer to windage losses. Another study is performed where the rotor and the enclosure geometries are fine-tuned simultaneously to reduce the negative effect on rotor heat transfer imposed by the enclosure. The final geometry of the rotor enclosure assembly is generated based on the research results and the design is integrated into the final machine prototype to be tested. / Thesis / Master of Applied Science (MASc) / Axial-flux permanent magnets (AFPM) machines are gaining the transportation electrification industy attention as a greener alternative to combustion engines in aircraft propulsion systems due to their high power and torque density. The intense endeavors of the current research to further improve AFPM machines power densities brings thermal design challenges to ensure the safe operation of the machine. Rotor permanent magnets failure due to demagnetization as a result of overheating can impose a great risk to the machine operation and safety. Accordingly, special attention should be paid to rotor thermal management. This research discusses the design process of an integrated rotor air cooling system for an AFPM machine designed for an electric aircraft. The machine mechanical and thermal design parameters are used to set an initial rotor design with different rotor cooling features based on literature findings. Rotor fan blades and air vents are selected as the main rotor cooling features for the design. Several design iterations are then made to fine-tune the rotor geometry targeting low operating temperature of the permanent magnets at a low cost of windage losses. The thermal performance of the different designs is assessed and compared to each other using conjugate heat transfer (CHT) computational fluid dynamics (CFD) analyses. Safe operating temperature of the magnets is achieved at an acceptable windage losses value with the final design, and it is selected for prototyping.

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This thesis focuses on utilizing the persistent voltage vector injections by finite control set model predictive control (FCSMPC) to enable simultaneous estimations of both position and parameters in order to realize robust sensorless interior permanent magnet synchronous machine (IPMSM) drives valid at the entire operating region including no-load standstill without any additional signal injection and switchover. The system (here, IPMSM) needs to meet certain observability conditions to identify the parameters and position. Moreover, each combination of the parameters and/or position involves different observability requirements which cannot be accomplished at every operating point. In particular, meeting the observability for parameters and position at no-load standstill is more challenging. This is overcome by generating persistent excitation in the system with high-frequency signal injection. The FCSMPC scheme inherently features the persistent excitation with voltage vector injection and hence no additional signal injection is required. Moreover, the persistent excitation always exists for FCSMPC except at the standstill where the control applies the null vectors when the reference currents are zero. However, introducing a small negative d axis current at the standstill would be sufficient to overcome this situation.The parameter estimations are investigated at first in this thesis. The observability is analyzed for the combinations of two, three and four parameters and experimentally validated by online identification based on recursive least square (RLS) based adaptive observer. The worst case operating points concerning observability are identified and experimentally proved that the online identification of all the parameter combinations could be accomplished with persistent excitation by FCMPC. Moreover, the effect of estimation error in one parameter on the other known as parameter coupling is reduced with the proposed decoupling technique. The persistent voltage vector injections by FCSMPC help to meet the observability conditions for estimating the position, especially at low speeds. However, the arbitrary nature of the switching ripples and absence of PWM modulator void the possibility of applying the standard demodulation based techniques for FCSMPC. Consequently, a nonlinear optimization based observer is proposed to estimate both the position and speed, and experimentally validated from standstill to maximum speed. Furthermore, a compensator is also proposed that prevents converging to saddle and symmetrical ( ambiguity) solutions. The robustness analysis of the proposed nonlinear optimization based observer shows that estimating the position without co-estimating the speed is more robust and the main influencing parameters on the accuracy of the position estimation are d and q inductances. Subsequently, the proposed nonlinear optimization based observer is extended to simultaneously estimate the position, d and q inductances. The experimental results show the substantial improvements in response time, and reduction in both steady and transient state position errors. In summary, this thesis presents the significance of persistent voltage vector injections in estimating both parameter and position, and also shows that nonlinear optimization based technique is an ideal candidate for robust sensorless FCSMPC. / Thesis / Doctor of Philosophy (PhD)