Study, analysis, and development of a small‐scale AC‐AC modular multilevel converter for solid‐state transformer applications

Abstract

The modular multilevel converter presents itself as a promising topology in medium voltage and high power applications due to its modular characteristic and flexibility in applications where DC-AC and AC-DC power conversion are required. Despite this, applications with electric traction present this topology in the AC-AC conversion due to the converter at the input of a solid-state transformer and the power system's single-phase characteristic at the converter's input. One of the main problems characteristic of this topology is the harmonic content present in the medium frequency converter output voltage due to its square waveform. Thus, the harmonic content in this voltage is high, increasing the losses and volume in the core of the medium frequency transformer. This paper presents a multilevel modulation scheme using two frequency components in the modulating wave to reduce the harmonic

Arm‐current sensorless model predictive control for grid‐interfacing modular multilevel converter with reduced switching frequency

“…2 Numerous control techniques for the MMCs have been reported in the literatures, such as classical linear control, sliding mode control, and model predictive control (MPC). [3][4][5][6] MPC-based control methods have attracted considerable attention from researchers as they provide superior dynamic performance. 7,8 Among the various MPC-based control methods, finite control set (FCS) MPC is a widely adopted one for the control of MMCs as it does not require modulators.…”

“…The switching states rise significantly as the number of voltage levels increases, leading to further escalation in the computational burden. 11 In order to reduce the computational burden, a fast MPC is suggested in Dekka et al, 12 which needs ðm þ 1Þ 3 switching states to optimize the cost function. In Dekka et al, 12 zero sequence components of the voltages are included in the MMC modeling, resulting in a discontinuous modulation scheme.…”

“…The control strategies play a crucial role in the effective utilization of the MMCs 2 . Numerous control techniques for the MMCs have been reported in the literatures, such as classical linear control, sliding mode control, and model predictive control (MPC) 3–6 . MPC‐based control methods have attracted considerable attention from researchers as they provide superior dynamic performance 7,8 …”