University of Tennessee, Knoxville TRACE: Tennessee Research and Creative Exchange Doctoral Dissertations Graduate School 12-2009 Development and Analysis of Interior Permanent Magnet Synchronous Motor with Field Excitation Structure Seong Taek Lee University of Tennessee - Knoxville Follow this and additional works at: https://trace.tennessee.edu/utk_graddiss Part of the Electrical and Computer Engineering Commons Recommended Citation Lee, Seong Taek, "Development and Analysis of Interior Permanent Magnet Synchronous Motor with Field Excitation Structure. " PhD diss., University of Tennessee, 2009. https://trace.tennessee.edu/utk_graddiss/613 This Dissertation is brought to you for free and open access by the Graduate School at TRACE: Tennessee Research and Creative Exchange. It has been accepted for inclusion in Doctoral Dissertations by an authorized administrator of TRACE: Tennessee Research and Creative Exchange. For more information, please contact [email protected]. To the Graduate Council: I am submitting herewith a dissertation written by Seong Taek Lee entitled "Development and Analysis of Interior Permanent Magnet Synchronous Motor with Field Excitation Structure." I have examined the final electronic copy of this dissertation for form and content and recommend that it be accepted in partial fulfillment of the equirr ements for the degree of Doctor of Philosophy, with a major in Electrical Engineering. Leon M. Tolbert, Major Professor We have read this dissertation and recommend its acceptance: Fangxing "Fran" Li, Kevin Tomsovic, Tsewei Wang Accepted for the Council: Carolyn R. Hodges Vice Provost and Dean of the Graduate School (Original signatures are on file with official studentecor r ds.) To the Graduate Council: I am submitting herewith a dissertation written by SeongTaek Lee entitled “Development and Analysis of Interior Permanent Magnet Synchronous Motor with Field Excitation Structure.” I have examined the final electronic copy of this dissertation for form and content and recommend that it be accepted in partial fulfillment of the requirements for the degree of Doctor of Philosophy, with a major in Electrical Engineering. Leon M. Tolbert, Major Professor We have read this dissertation and recommend its acceptance: Fangxing “Fran” Li Kevin Tomsovic Tsewei Wang Accepted for the Council: Carolyn R. Hodges Vice Provost and Dean of the Graduate School (Original signatures are on file with official student records) Development and Analysis of Interior Permanent Magnet Synchronous Motor with Field Excitation Structure A Dissertation Presented for the degree of Doctor of Philosophy The University of Tennessee, Knoxville Seong Taek Lee December 2009 DEDICATION This dissertation is dedicated to my family; my wife Min-young, my daughter Jennifer, and my mother, who are always encouraging me with their love. ii ACKNOWLEDGMENTS I wish to thank all those who helped me in completing my degree during my graduate studies in the University of Tennessee. Several persons collaborated directly and indirectly with my research and encouraged me to finish the works. That is why I wish to dedicate this section to recognize their support. I thank my research advisor, Dr. Tolbert, for his continuous guidance throughout the process of performing my research and organizing this dissertation. He always showed me the right direction to finish this work with his passion and supported me throughout all the way. I thank all the professors in my committee, Dr. Li, Dr. Tomsovic, and Dr. Wang, who gave me advice whenever I asked. I owe my sincere gratitude to all professors who guided me to have engineering scope. I would also like to thank the Power Electronics and Electric Machinery Research Center (PEEMRC) at the Oak Ridge National Laboratory to give me the chance to research there. In particular, I would like to thank Dr. John Hsu who actually gave me the chance to research this topic and has supported and encouraged me while I was pursuing my degree. I am also thankful to the other persons at PEEMRC for sharing their profound experience and knowledge of electrical machines with me. iii ABSTRACT Throughout the years Hybrid Electric Vehicles (HEV) require an electric motor which has high power density, high efficiency, and wide constant power operating region as well as low manufacturing cost. For these purposes, a new Interior Permanent Magnet Synchronous Motor (IPMSM) with brushless field excitation (BFE) is designed and analyzed. This unique BFE structure is devised to control the amount of the air-gap flux for the purpose of achieving higher torque by increasing the air-gap flux at low speed and wider operating speed range by weakening the flux at high speed. On the process of developing the new IPMSM, the following analysis results are presented. Firstly, a new analytical method of output torque calculations for IPMSM is shown. This method works well when using a 2-dimensional magnetic equivalent circuit of a machine by omitting the step of calculating the inductance values which are required for the calculation of the reluctance torque. Secondly, there is a research about the slanted air-gap shape. This structure is intended to maximize the ratio of the back-emf of a machine that is controllable by BFE as well as increase the output torque. The study of various slanted air-gap shapes suggests a new method to increase torque density of IPMSM. Lastly, the conventional two-axis IPMSM model is modified to include the cross saturation effect by adding the cross-coupled inductance terms for calculating the power factor and output torque in comparing different saturated conditions. The results suggest that the effect of cross-coupled inductance is increase when d-axis current is high on the negative direction. iv LIST OF CONTENTS 1. Introduction 1.1. Overview ....................................................................................................1 1.2. Permanent Magnet Synchronous Motors ...................................................6 1.2.1. Permanent magnet materials ...........................................................6 1.2.2. Interior permanent magnet synchronous motor ............................10 1.3. Research Objective ..................................................................................13 1.4. Dissertation Organization ........................................................................15 2. Literature Review: Analysis of Interior Permanent Magnet Synchronous Motor (IPMSM) 2.1. Introduction ..............................................................................................17 2.2. The Steady-State Modeling of IPMSM ...................................................18 2.3. Circle Diagram of IPMSM ......................................................................23 2.4. Simple Magnetic Circuit with a Permanent Magnet ................................27 2.5. Magnetic Circuit Analysis of Simple IPMSM .........................................30 2.5.1. Tangential magnetization ..............................................................30 2.5.2. Radial magnetization ....................................................................35 2.5.3. Two-dimensional network equivalent circuit ................................37 2.6. Current Density and Flux Linkage in 3-Phase Winding Distribution .....39 v 2.7. Inductances of IPMSM ............................................................................46 2.7.1. Analytical method for tangential magnetization ...........................47 2.7.2. Analytical method for radial magnetization .................................53 2.7.3. Using 2-dimensional network equivalent circuit ..........................56 2.7.4. Energy method for inductance calculation ...................................57 2.7.5. Consideration of the saturation .....................................................61 2.8. Finite Element Analysis – Maxwell 3D ...................................................64 2.9. Summary ...................................................................................................68 3. New Features of the IPMSM 3.1. Introduction ..............................................................................................69 3.2. Side Magnetic Flux ..................................................................................70 3.2.1. Structures of the side permanent magnet ......................................71 3.2.2. Rotor structure with DC current excitation ...................................78 3.3. Slanted Rotor Structure ............................................................................80 3.3.1. Structures of the side permanent magnet ......................................81 3.3.2. FEA simulation results ...................................................................83 3.4. Summary ...................................................................................................88 4. New Analytical Method of Output Torque Calculation and Analysis of Various Slanted Air-gap Shape 4.1. Introduction ..............................................................................................90 4.2. New Analytical Method of Output Torque Calculation for an IPMSM ..91 vi 4.2.1. Concept of new method ................................................................92 4.2.2. Verifying the method: Analysis of Prius IPMSM .........................94 4.3. Determination of the Slant Air-gap Structure ........................................108 4.3.1. Equivalent circuit with brushless field excitation structure ........109