高性能無刷馬達在全球工業應用上佔有舉足輕重的地位，而近年來電動載具的快速發展也使其應用更加廣泛。然而無刷馬達多使用變頻器加以驅動，其因需要針對功率晶體進行高速切換，因此易衍生軸承電流，造成軸承損壞，進而影響馬達使用壽命。此外，由於碳化矽功率元件的興起使得切換頻率更為提高，進一步加劇軸承電流的產生。
　　馬達共模電壓與軸承電流息息相關，藉由控制共模電壓的大小變化頻率即可有效抑制軸承電流。因此本文針對變頻器之開關切換法進行分析，推得使用兩相調變的七開關變頻器在一電氣週期內，能降低開關切換及共模電壓變化次數，且在高切換頻率下能有較佳的驅動表現。本文亦同時考量死區時間(Dead time)及寄生元件之效應，且針對其電路特性進行分析及模擬。最後，本文設計一基於碳化矽功率元件之驅動電路，並以實驗佐證本文所提方法之有效性。

High-performance brushless motors occupy a pivotal position in global industrial applications, and the rapid development of electric vehicles in recent years has also made their applications more widely. However, brushless motors are mostly driven by inverters, and power transistors require high-speed switching, which accordingly easily generates bearing current which can damage the bearing and further affect the service life of the motor. In addition, due to the rise of SiC power transistors, the switching frequency has been increased, which further aggravates the generation of bearing currents.
The common-mode voltage of the motor is closely related to the bearing current, and the bearing current can be effectively suppressed by controlling the frequency of the common-mode voltage change. Therefore, this thesis analyzes the switching method of the frequency converter. It is concluded that a seven-switch inverter with two-phase modulation can reduce the number of switching and common-mode voltage changes in one electrical period and has better driving performance at high switching frequencies. This thesis also considers the effects of dead time and parasitic components and conducts analysis and simulation for its circuit characteristics. Finally, this thesis designs a motor drive based on SiC power transistors and proves the effectiveness of the method proposed in this thesis through experiments.

[1] 黃樑傑，「2017年國際電動車現況與展望」(2021, July)，Available: https://www.artc.org.tw/upfiles/ADUpload/knowledge/tw_knowledge_559943710.pdf
[2] F. Lambert, “Cadillac is going electric – every new vehicle will be all-electric starting now, ” electrek, Apr. 2021
[3] 星展亞洲，「2030趨勢預測–可再生能源使用攀升」(2021, July)，Available: https://www.dbs.com/livemore/tw-zh/serious-talk/wm334.html
[4] S. Chen, T. A. Lipo, and D. Fitzgerald, “Source of induction motor bearing currents caused by PWM inverters,” IEEE Transactions on Energy Conversion, March 1996, vol. 11, no. 1, pp. 25-32
[5] 東培工業股份有限公司，「軸承發生電蝕現象之原因與對策」(2021, July)，Available: https://www.tpi.tw/webls-zh-tw/msg/msg57.html
[6] 金富喬國際有限公司，「絕緣軸承與軸電流」(2021, July)，Available: https://chin-fu-chiao.com.tw/news_detail.php?id=258
[7] 葛世偉、李明遠，「馬達軸承故障線上診斷技術研究」(2021, July)
，Available: http://support.bentech-taiwan.com/mobile/WEBDAQ/p41uzcz21y.pdf
[8] D. Gesualdo, “SiC and GaN: Let’s Take Stock of the Situation,” EE Times, (2021, July), Available: https://www.eetimes.eu/sic-and-gan-lets-take-stock-of-the-situation/
[9] ROHM，「何謂SiC MOSFET－SiC MOSFET的可靠性」(2021, July)，Available: https://techweb.rohm.com.tw/knowledge/sic/s-sic/04-s-sic/6888
[10] 捷能動力，「EDM1-S馬達規格」(2021, July)，Available: https://www.zept.com.tw/edm1-s-p95
[11] Yole Développement, “Power SiC : Materials, Devices and Applications 2020, ” i-MicroNEWS, 2020
[12] R. F. Schiferl, and M. J. Melfi, “Bearing current remediation options,” IEEE Industry Applications Magazine, July-Aug. 2004, vol. 10, no. 4, pp. 40-50
[13] AEGIS, “AEGIS Shaft Grounding in Wind Turbine Generators,” (2021, July), Available: https://est-aegis.info/2020/05/aegis-in-wind-turbine-generators/
[14] AEGIS, “ABB Launches AEGIS Shaft Grounding Ring Option Code VC588 for IEC Motors,” (2021, July), Available: https://est-aegis.info/2018/10/abb-launches-aegis-shaft-grounding-ring-option-code-vc588-for-iec-motors/
[15] 張家寧，永磁同步馬達軸承電流之抑制研究，國立成功大學電機工程學系碩士論文，2017
[16] 新豐貿易股份有限公司，「SKF絕緣軸承」(2021 July)，Available: https://www.hht.tw/zh-tw/product-484439/SKF%E7%B5%95%E7%B7%A3%E8%BB%B8%E6%89%BF-INSOCOAT.html
[17] 品源科技，「專業提供培林,高溫軸承鋼,陶瓷軸承,塑料軸承,不鏽鋼軸承」(2021, July)，Available: http://pukg8585.com.tw/product-1_1.html
[18] 新豐貿易股份有限公司，「SKF混合陶瓷軸承」(2021 July)，Available: https://www.hht.tw/zh-tw/product-486776/SKF%E6%B7%B7%E5%90%88%E9%99%B6%E7%93%B7%E8%BB%B8%E6%89%BFHC5C3WT.html
[19] AEGIS, “How Do Shaft Grounding Brushes Compare with AEGIS Rings,” (2021, July), Available: https://est-aegis.info/2020/05/how-do-shaft-grounding-brushes-compare-with-aegis-rings/
[20] O. Magdun, Y. Gemeinder, and A. Binder, “Prevention of harmful EDM currents in inverter-fed AC machines by use of electrostatic shields in the stator winding overhang,” in Proc. IECON 2010 - 36th Annual Conference on IEEE Industrial Electronics Society, 2010, pp. 962-967
[21] S. Gerber and R. Wangi, “Reduction of Inverter-Induced Shaft Voltages Using Electrostatic Shielding,” in Proc. 2019 Southern African Universities Power Engineering Conference /Robotics and Mechatronics/Pattern Recognition Association of South Africa (SAUPEC/RobMech/PRASA), 2019, pp. 310-315
[22] L. Concari, D. Barater, G. Buticchi, C. Concari, and M. Liserre, “H8 Inverter for Common-Mode Voltage Reduction in Electric Drives,” IEEE Transactions on Industry Applications, Sept.-Oct. 2016, vol. 52, no. 5, pp. 4010-4019
[23] C. Hou, “A discontinuous PWM for three level converters with constant common-mode voltage,” in Proc. 2013 1st International Future Energy Electronics Conference (IFEEC), 2013, pp. 395-399
[24] 林賢忠，變頻器驅動之馬達共模電壓抑制策略研究，南台科技大學電機工程系碩士論文，2004
[25] S. Lee, J. Jung, S. Hwnag, J. Kim, and H. Cho, “Common Mode Voltage Reduction Method for H7 Inverter Using DPWM Offset Based Modulation Technique,” in Proc. 2018 IEEE Energy Conversion Congress and Exposition (ECCE), 2018, pp. 1790-1795
[26] W. Jung, K. Choo, J. Kim, W. Kim, and C. Won, “H7 Inverter Using Zener Diode With Model Predictive Current Control for Common-Mode Voltage Reduction in PMSM Drive System,” in Proc. 2018 IEEE International Power Electronics and Application Conference and Exposition (PEAC), 2018, pp. 1-6
[27] T. K. S. Freddy, N. A. Rahim, W. Hew, and H. S. Che, “Modulation Techniques to Reduce Leakage Current in Three-Phase Transformerless H7 Photovoltaic Inverter,” IEEE Transactions on Industrial Electronics, Jan. 2015, vol. 62, no. 1, pp. 322-331
[28] X. Guo, D. Xu, and B. Wu, “Three-phase seven-switch inverter with common mode voltage reduction for transformerless photovoltaic system,” in Proc. IECON 2014 - 40th Annual Conference of the IEEE Industrial Electronics Society, 2014, pp. 2279-2284
[29] W. S. Jeong, K. M. Choo, J. H. Lee, and C. Y. Won, “A Common-Mode Voltage Reduction Method of FCS-MPC in H8 Inverter for SPMSM Drive System Considering Dead-Time Effect,” in Proc. 2019 10th International Conference on Power Electronics and ECCE Asia (ICPE 2019 - ECCE Asia), 2019, pp. 1-8
[30] L. Concari, D. Barater, C. Concari, A. Toscani, G. Buticchi, and M. Liserre, “H8 architecture for reduced common-mode voltage three-phase PV converters with silicon and SiC power switches,” in Proc. IECON 2017 - 43rd Annual Conference of the IEEE Industrial Electronics Society, 2017, pp. 4227-4232
[31] Q. Tang, X. Ge, and Y. Liu, “Performance analysis of two different SVM-based field-oriented control schemes for eight-switch three-phase inverter-fed induction motor drives,: in Proc. 2016 IEEE 8th International Power Electronics and Motion Control Conference (IPEMC-ECCE Asia), 2016, pp. 3374-3378
[32] C. T. Morris, D. Han, and B. Sarlioglu, “Reduction of Common Mode Voltage and Conducted EMI Through Three-Phase Inverter Topology,” IEEE Transactions on Power Electronics, March 2017, vol. 32, no. 3, pp. 1720-1724
[33] M. Wang, X. Pei, Y. Xiang, and Y. Kang, “Reduction of Common Mode Voltage Through Improved Three-Phase Inverter Topology,” in Proc. 2018 IEEE International Power Electronics and Application Conference and Exposition (PEAC), 2018, pp. 1-5
[34] A. Syed and S. T. Kalyani, “Three-phase eight switch inverter with reduced common mode voltage for transformerless photovoltaic systems,” in Proc. 2016 International Conference on Electrical, Electronics, and Optimization Techniques (ICEEOT), 2016, pp. 2840-2844
[35] Adlee，「MA2 3700M馬達規格」(2021, July)，Available: https://www.adlee.com/zh-tw/product-552510/%E7%84%A1%E5%88%B7%E4%BC%BA%E6%9C%8D%E9%A6%AC%E9%81%94.html#ma2
[36] ROHM, “SCT3060AL N-channel SiC power MOSFET,” datasheet, Jun. 2018
[37] STMicroelectronics, “STTH15L06G-TR Fast Recovery Rectifiers,” datasheet, Apr. 2014
[38] LEM, “current transducer LA 55-P,” Datasheet, Sept. 2018.
[39] Texas Instruments, “TMS320F2837xD Dual-Core Delfino™ Microcontrollers”, Datasheet, Nov. 2018