Abstract
Modular multilevel power electronic converters are considered an
increasingly critical family of converters for myriad high voltage high
power applications. With the ever-growing emphasis on electrification of
the economy, they play a crucial role in serving energy sources and
loads whose electrical ratings go beyond the ratings of the conventional
power electronic building blocks. In particular, modular multilevel
converter (MMC) topology enjoy its dominance in such applications due to
modularity, scalability, performance and fault-tolerance capability.
However, the MMC topology design imposes low-frequency ac components on
the module capacitors and thus is inhibited by the capacitor size.
Capacitor sizing plays a significant role in the overall system’s size,
cost and reliability. This paper introduces a minimal capacitor module
based topology for DC to three-phase AC conversion. The unique design
feature of the module includes minimal capacitor requirement due to
elimination of single-phase ac power processing requirements. Together
with improved power density, reduction of capacitor size permits the use
of only film capacitors thus eliminating the weakest link of the overall
system. Along with the step-by-step analytical derivation of the
proposed approach, the paper presents detailed simulation studies,
comparative analysis and experimental results from a proof-of-concept
laboratory-scale prototype.