Abstract
The low-frequency fluctuation over the capacitor voltages seriously limits the development of medium-voltage variable-speed drives with a modular multilevel converter (MMC). Therefore, this paper presents an effective strategy of the low-speed and start-up operation for an MMC-based motor drive. The proposed strategy properly coordinates the improved injection and the reduced average capacitor voltage with high applicability. The specific interactions between the control parameters and the system metrics are analyzed to give the detailed steps of the parameters designing. Hence, based on the derivations, the proposed method enables the low-frequency operation under the nominal load torque with decreased injected components and reduced peak capacitor voltages. What is more, two start-up strategies that, respectively, aim at different objectives for the coordinated strategy are proposed, indicating satisfying control performances for the practical applications. The injected common-mode voltage and circulating current in the proposed method are designed to have a great reduction. Thus, the unfavorable risks for the motor are evidently decreased for better stability. The reduced peak current also lessens the high stress on switching devices with desirable reliability. The simulation and experiment results of an MMC-based motor drive prototype prove the effectiveness and superiority of the proposed method.
Original language | English |
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Article number | 8701485 |
Journal | IEEE Transactions on Power Electronics |
Volume | 35 |
Issue number | 1 |
Pages (from-to) | 709-724 |
Number of pages | 16 |
ISSN | 0885-8993 |
DOIs | |
Publication status | Published - Jan 2020 |
Externally published | Yes |
Bibliographical note
Funding Information:Manuscript received December 3, 2018; revised March 1, 2019; accepted April 22, 2019. Date of publication April 28, 2019; date of current version October 18, 2019. This work was supported by the National Natural Science Foundation of China under Project 51277146. Recommended for publication by Associate Editor N. R. Zargari. (Corresponding author: Fangzhou Zhao.) F. Zhao, G. Xiao, T. Zhu, X. Zheng, and Z. Wu are with the State Key Laboratory of Electrical Insulation and Power Equipment, School of Electrical Engineering, Xi’an Jiaotong University, Xi’an 710049, China (e-mail: zfzhaha@stu.xjtu.edu.cn; xgc@mail.xjtu.edu.cn; zth1222@163.com; zhengxu201706@stu.xjtu.edu.cn; wzq342910214@stu.xjtu.edu.cn).
Publisher Copyright:
© 1986-2012 IEEE.
Keywords
- Coordinated strategy
- low-frequency fluctuation
- modular multilevel converter (MMC)
- motor drives