A Novel Flexible Capacitor Voltage Control Strategy for Variable-Speed Drives With Modular Multilevel Converters
A Novel Flexible Capacitor Voltage Control Strategy for Variable-Speed Drives With Modular Multilevel Converters
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DOI：
10.1109/tpel.2016.2535463
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发表时间：
2017
影响因子：
6.7
通讯作者：
Bingyong Tai;Congzhe Gao;Xiangdong Liu;Zhen Chen
中科院分区：
文献类型：
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作者：
Bingyong Tai;Congzhe Gao;Xiangdong Liu;Zhen Chen
模块化多电平变流器(MMC)在高压直流输电、静止无功发生器、电机驱动等中压领域有着广泛的应用。在以往的研究中，MMC的臂电容电压通常是恒定的，输出电压是通过调节开关的脉宽调制(PWM)指数来调节的。提出了一种新型的用于MMC电机驱动的柔性电容电压控制策略，该策略通过调节PWM参考信号的直流分量和交流分量，根据电机转速灵活控制臂电容电压，并对MMC的上臂和下臂进行不对称控制。在电机转速较低时，该控制策略可以提高变流器的电路效率和输出电压精度，减小电机绕组的di/dt和dv/dt。这些建议已在实验室样机上实施，并进行了实验。验证了该控制策略在稳态和动态下的有效性。
Modular multilevel converter (MMC) is very popular in medium-voltage applications, such as high-voltage direct current transmission, static Var generator, and motor drives. The arm capacitor voltage of MMC is usually constant and the output voltage is adjusted by regulating the pulse width modulation (PWM) index for switches in previous studies. In this paper, a novel flexible capacitor voltage control strategy for MMC as motor drives was proposed, with which the arm capacitor voltage was controlled flexibly according to the motor speed, by regulating the dc component and ac component of the PWM reference signal, and unsymmetrical control was used for the control of the upper arm and the lower arm in MMC. With the proposed control strategy, the circuit efficiency and the precision of the output voltage of the converter could be improved when the motor speed was low, and di/dt and d v/dt of the motor windings could be decreased. These proposals were implemented on a laboratory prototype, and experiments were carried out. The validity of the control strategy under both steady and dynamic states was verified.