近年來，全球各國積極致力於降低二氧化碳排放，使得電動搬運載具需求急遽增加。然而，作為電動載具心臟的馬達，其驅動系統產生的轉矩漣波不可忽視。這不僅對搬運過程的穩定性產生負面影響，同時也會增加能量損耗，進而影響效率，直接對電池的壽命與操作成本產生不良影響。為改善此問題，本文提出以模型預測轉矩控制作為驅動法，同時結合直流鏈電壓調控以抑制轉矩漣波，以達到高轉矩響應且有效改善轉矩漣波之目的。
本文旨在透過降壓型轉換器降低直流鏈電壓，以提升變頻器功率開關之工作週期，降低變頻器非線性效應。文中以公式推導闡述直流鏈電壓對於轉矩漣波與磁交鏈漣波的關係，同時說明改善漣波對於模型預測轉矩控制的直接關係。本文透過實測，驗證降低直流鏈電壓對於中低速轉速各負載下皆有效抑制轉矩漣波、三相電流總諧波失真，此外，確認亦有效提高系統效率，對於本文馬達在半載可改善約8.75%，額定負載改善4.79%，1.5倍負載改善3.43%。

In recent years, countries worldwide have actively committed to reducing carbon dioxide emissions, leading to a rapid increase in demand for electric handling vehicles. However, as electric motors serve as the heart of electric vehicles, the torque ripple generated by its drive system cannot be ignored. This not only has a negative impact on the stability of the handling process but also increases energy consumption, thereby affecting efficiency. It directly results in adverse effects on the battery life and operational costs. To address this issue, this thesis proposes using model predictive torque control as a driving method, combined with DC link voltage regulation to suppress torque ripple, aiming to achieve high torque response and effectively improve torque ripple.
The thesis aims to reduce the DC link voltage through a BUCK converter to enhance the operating duty cycle of the power switches in the inverter, thereby reducing the non-linear effects of the inverter. The thesis derives formulas to explain the relationship between DC link voltage and torque ripple as well as flux linkage ripple. It also illustrates the direct relationship between improving ripple and model predictive torque control. Through experimentation, the thesis verifies that reducing the DC link voltage effectively suppresses torque ripple and total harmonic distortion of three-phase currents under various loads and speeds. Additionally, it confirms an improvement in system efficiency, with the motor in this thesis showing an improvement of approximately 8.75% under half-rated load, 4.79% under rated load, and 3.43% under 1.5 times the rated load.

[1] S. Doherty and S. Hoyle “Supply chain decarbonization, the role of logistics and transport in reducing supply chain carbon emissions” World Economic Forum, 2009.
[2] F. Boenzi, S. Digiesi, F. Facchini and G. Mummmolo, "Electric and LPG forklifts GHG assessment in material handling activities in actual operational conditions," in Proceedings of IEEE International Conference on Service Operations and Logistics, and Informatics (SOLI), pp. 127-132, Nov. 2017.
[3] K. C. T. Vivaldini, J. P. M. Galdames, T. S. Bueno, R. C. Araujo, R. M. Sobral, M. Becker and G. A. P. Caurin, "Robotic forklifts for intelligent warehouses: routing, path planning, and auto-localization," in Proceedings of IEEE International Conference on Industrial Technology, pp.1463-1468, May. 2010.
[4] T. A. Minav, L. I. E. Laurila, P. A. Immonen, M. E. Haapala and J. J. Pyrhonen, "Electric energy recovery system efficiency in a hydraulic forklift," in Proceedings of IEEE EUROCON, pp. 758-765, Jul. 2009.
[5] Q. Lin, S. Niu, F. Cai, W. Fu and L. Shang, "Design and optimization of a novel dual-PM machine for electric vehicle applications," IEEE Transactions on Vehicular Technology, vol. 69, no. 12, pp. 14391-14400, Dec. 2020.
[6] C. Xia, B. Ji and Y. Yan, "Smooth speed control for low-speed high-torque permanent-magnet synchronous motor using proportional–integral–resonant controller," IEEE Transactions on Industrial Electronics, vol. 62, no. 4, pp. 2123-2134, Apr. 2015.
[7] J. Gao, X. Wu, S. Huang, W. Zhang, and L. Xiao, “Torque ripple minimisation of permanent magnet synchronous motor using a new proportional resonant controller,” IET Power Electronics, Feb. 2017.
[8] L. Liu, G. Götting and J. Xie, "Torque ripple reduction using variable DC-link voltage technique for permanent magnet synchronous motor in battery electric vehicle," in Proceedings of IEEE 29th International Symposium on Industrial Electronics (ISIE), pp. 374-379, Jul. 2020.
[9] L. Wu and Z. Lyu, "Harmonic injection-based torque ripple reduction of PMSM with improved DC-link voltage utilization," IEEE Transactions on Power Electronics, vol. 38, no. 7, pp. 7976-7981, Jul. 2023.
[10] T. Geyer, G. A. Beccuti, G. Papafotiou and M. Morari, "Model predictive direct torque control of permanent magnet synchronous motors," in Proceedings of IEEE Energy Conversion Congress and Exposition, pp. 199-206, Nov. 2010.
[11] Y. Zhang, D. Xu and L. Huang, "Generalized multiple-vector-based model predictive control for PMSM drives," IEEE Transactions on Industrial Electronics, vol. 65, no. 12, pp. 9356-9366, Dec. 2018.
[12] X. Li, Z. Xue, X. Yan, L. Zhang, W. Ma and W. Hua, "Low-complexity multivector-based model predictive torque control for PMSM with voltage preselection," IEEE Transactions on Power Electronics, vol. 36, no. 10, pp. 11726-11738, Oct. 2021.
[13] L. Chen, H. Xu, X. Sun and Y. Cai, "Three-vector-based model predictive torque control for a permanent magnet synchronous motor of EVs," IEEE Transactions on Transportation Electrification, vol. 7, no. 3, pp. 1454-1465, Sept. 2021.
[14] S. W. Kang, J. H. Soh and R. Y. Kim, "Symmetrical three-vector-based model predictive control with deadbeat solution for IPMSM in rotating reference frame," IEEE Transactions on Industrial Electronics, vol. 67, no. 1, pp. 159-168, Jan. 2020.
[15] Ki-Yong Nam, Woo-Taik Lee, Choon-Man Lee and Jung-Pyo Hong, "Reducing torque ripple of brushless DC motor by varying input voltage," IEEE Transactions on Magnetics, vol. 42, no. 4, pp. 1307-1310, Apr. 2006.
[16] R. A. Raj, D. S. Nair, S. MP and S. George, "A novel high-voltage gain circuit topology for commutation torque ripple reduction," IEEE Transactions on Industry Applications, vol. 58, no. 5, pp. 6227-6236, Sept.-Oct. 2022.
[17] K. S. Nithin, R. S. Vivek, M. Krishna and A. Purushothaman, "Commutation torque ripple comparison in cuk converter fed brushless DC motor drives with mode switching selection circuit," in Proceedings of International Conference on Power Electronics and Renewable Energy Applications (PEREA), pp. 1-6, Nov. 2020.
[18] C. L. Huang, F. C. Lee, C. J. Liu, J. Y. Chen, Y. J. Lin and S. C. Yang, "Torque ripple reduction for BLDC permanent magnet motor drive using DC-link voltage and zcurrent modulation," IEEE Access, vol. 10, pp. 51272-51284, Jan. 2022.
[19] F. Korkmaz, İ. Topaloğlu, M. F. Çakir and R. Gürbüz, "Comparative performance evaluation of FOC and DTC controlled PMSM drives," in Proceedings of 4th International Conference on Power Engineering, Energy and Electrical Drives, pp. 705-708, Oct. 2013.
[20] F. Wang, K. Zuo, P. Tao and J. Rodríguez, "High performance model predictive control for PMSM by using stator current mathematical model self-regulation technique," IEEE Transactions on Power Electronics, vol. 35, no. 12, pp. 13652-13662, Dec. 2020.
[21] T. Wang, Y. Guo and J. Zhu, "Finite-control-set model predictive direct torque control of PMSMs with virtual space vectors," in Proceedings of IEEE Conference on Industrial Electronics and Applications (ICIEA), pp. 1427-1430, Feb. 2017.
[22] P. Cortes, S. Kouro, B. L. Rocca, R. Vargas, J. Rodriguez, J. I. Leon, S. Vazquez and L. G. Franquelo, "Guidelines for weighting factors design in Model Predictive Control of power converters and drives," in Proceedings of IEEE International Conference on Industrial Technology, pp. 1-7, Feb. 2009.
[23] S. Liu, W. Huang, X. Lin, Y. Zhao, W. Jiang and J. Yang, "Maximum torque per ampere control based on active flux concept for DTC of IPMSMs," in Proceedings of IEEE Energy Conversion Congress and Exposition (ECCE), pp. 6558-6562, Sept. 2018.
[24] I. Boldea, M. C. Paicu and G. -D. Andreescu, "Active flux concept for motion-sensorless unified AC drives," IEEE Transactions on Power Electronics, vol. 23, no. 5, pp. 2612-2618, Sept. 2008.
[25] 吳政軒，可調工作週期之永磁同步電機直接轉矩控制，國立成功大學碩士論文，2020。
[26] S. Song, G. Fang, R. Hei, J. Jiang, R. Ma and W. Liu, "Torque ripple and efficiency online optimization of switched reluctance machine based on torque per ampere characteristics," IEEE Transactions on Power Electronics, vol. 35, no. 9, pp. 9608-9616, Sept. 2020.
[27] 鍾翔安，以電壓調變抑制變頻器非線性效應之無轉子位置感測器控制法，國立成功大學碩士論文，2023。
[28] ROHM, “SCT3060AL, N-channel SiC power MOSFET”, Datasheet, Nov. 2022.
[29] WeEn, “BYC30JT-600PS, Hyperfast power diode”, Datasheet, Sep. 2021.
[30] 劉哲瑜，以直流鏈電壓調控提升內藏型永磁同步馬達之高效率操作區間，國立成功大學碩士論文，2022。
[31] C. M. Wildrick, F. C. Lee, B. H. Cho and B. Choi, "A method of defining the load impedance specification for a stable distributed power system," IEEE Transactions on Power Electronics, vol. 10, no. 3, pp. 280-285, May. 1995.
[32] G. Yu, D. Zhang and H. Zhu, "Adaptive impedance matching optimal control method for cascaded DC-DC power supply system,"in Proceedings of IECON 2017 - 43rd Annual Conference of the IEEE Industrial Electronics Society, pp. 751-755, Dec. 2017.
[33] TEXAS INSTRUMENTS, “TMS320F2837xD Dual-Core Microcontorllers”, Datasheet, Feb. 2021.