中文摘要：

模块化多电平换流器（MMC）的预充电通常可分为两个阶段：不控整流以及boost升压。三相MMC的boost升压控制技术已经较为成熟。然而与三相MMC不同的是,单相MMC的直流侧具有独立电容。因此,单相MMC的boost升压阶段必须同时考虑子模块电容和直流侧电容,这是单相MMC预充电的难点所在。文中提出了一种基于单相半桥子模块（HBSM）的预充电策略。该策略的第一阶段仍为不控整流,第二阶段通过上下桥臂的能量之和与能量之差的控制来实现子模块电容的boost升压。之后,直流侧电容电压被交流侧持续馈入的能量充到额定值。该控制方案使整个启动过程快速、平滑、稳定,对单相MMC做整流运行具有重大价值。最后,所提方案的有效性及正确性在一台单相8个子模块的实验样机上得到了验证。

英文摘要：

Pre-charging control scheme for a modular multilevel converter （MMC） can be generally divided into two stages, viz., the uncontrolled rectifying and voltage boosting. Voltage boosting control scheme of three-phase MMC is mature. However, different from the three-phase MMC, single-phase has exclusive capacitor in the dc bus. As a result, voltage boosting stage of single-phase MMC has to take both the sub-module capacitor and dc bus capacitor into consideration, and has become an obstacle for single-phase MMC. This paper presents a pre-charging scheme for a single-phase half-bridge sub-module （HBSM）-based MMC. The uncontrolled rectifying stage is also adopted. The sum and the difference of energy between the upper and lower arms are controlled to realize the voltage boosting of sub-modules. Moreover, the dc bus capacitors are charged to the rated voltage value by the rest energy flowing from the AC side. This control scheme can make the starting process rapidly, smoothly and stably, which is of great value for a single-phase MMC operating as a rectifier. A prototype of a single-phase MMC with 8 sub-modules per arm was built to demonstrate the effectiveness and validity of the proposed control scheme.