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Modeling and Analysis of Asymmetries in Permanent Magnet Synchronous Machines

Pina Ortega, Alejandro Jose

Abstract Details

2016, Doctor of Philosophy, Ohio State University, 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 permeability in the analytic model. The analysis of radial forces showed that new vibration modes occur due to unbalanced radial pressure, which then introduce new resonance frequencies. Additionally, a geometry optimized to minimize torque ripple through controlled-asymmetry compensates harmonics in torque efficiently, but such compensation does not occur in the same manner on radial forces. The results suggest that neglecting the tolerances in the analysis might underestimate the resultant torque ripple by as much as 75\%. On the other hand, when appropriately using controlled-asymmetries, up to 90\% of reduction in the amplitude of torque pulsations are achieved. Furthermore, the effect of tolerances can be mitigated in introducing controlled-asymmetries since both cases produce similar harmonic orders in tangential and radial forces.
Longya Xu (Advisor)
Vadim Utkin (Committee Member)
Mahesh Illindala (Committee Member)
211 p.

Recommended Citations

Citations

  • Pina Ortega, A. J. (2016). Modeling and Analysis of Asymmetries in Permanent Magnet Synchronous Machines [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1469034099

    APA Style (7th edition)

  • Pina Ortega, Alejandro. Modeling and Analysis of Asymmetries in Permanent Magnet Synchronous Machines. 2016. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1469034099.

    MLA Style (8th edition)

  • Pina Ortega, Alejandro. "Modeling and Analysis of Asymmetries in Permanent Magnet Synchronous Machines." Doctoral dissertation, Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1469034099

    Chicago Manual of Style (17th edition)