Modular Converter-Based Multiport Chargers – III | Cascaded H-Bridge (CHB) & Modular Multilevel Converter (MMC) | EV Charging | Lecture 19

As the demand for high-power and fast EV charging stations continues to grow, modular multilevel converter topologies are becoming the preferred choice due to their scalability, superior power quality, and modular architecture. In this lecture, we continue our study of Modular Converter-Based Multiport Chargers by exploring the Cascaded H-Bridge (CHB) Multilevel Converter and the Modular Multilevel Converter (MMC) in detail. The lecture explains their construction, operating principles, switching states, voltage level generation, advantages, disadvantages, and practical applications in electric vehicle charging systems.

The lecture introduces the Modular Multilevel Converter (MMC), one of the most significant advancements in Voltage Source Converter (VSC) technology. The construction of Half-Bridge and Full-Bridge Submodules, arm structure, capacitor-based submodules, insertion and bypass operation, output voltage generation, and the submodule selection (sorting) algorithm for capacitor voltage balancing are explained step-by-step using switching waveforms. The advantages of MMC—including modularity, scalability, reduced switching stress, low harmonic distortion, high efficiency, and reduced filtering requirements—are also discussed, along with its application in multiport EV chargers, medium-voltage DC–DC converters, and high-power charging infrastructure. The lecture concludes with a comparison between Conventional Transformers and Solid-State Transformers (SSTs), highlighting the role of SSTs in future smart grids and EV charging applications.

Topics Covered

Cascaded H-Bridge (CHB) Multilevel Converter
Voltage Level Generation in CHB
Advantages, Disadvantages, and Applications of CHB
Introduction to Modular Multilevel Converter (MMC)
Half-Bridge and Full-Bridge Submodules
MMC Construction and Arm Structure
Output Voltage Generation in MMC
Capacitor Voltage Balancing using Sorting Algorithm
Advantages and Disadvantages of MMC
MMC-Based Multiport EV Chargers
MMC as a DC–DC Converter
Conventional Transformer vs Solid-State Transformer (SST)

Who Should Watch?

B.Tech. and M.Tech. students
Power Electronics learners
Electric Vehicle enthusiasts
GATE and ESE aspirants
Researchers working on multilevel converters and EV charging infrastructure
Engineers designing high-power converters, HVDC systems, and modular EV chargers

Recommended References

J. Rodríguez, J.-S. Lai, and F. Z. Peng, Multilevel Inverters: A Survey of Topologies, Controls, and Applications, IEEE Transactions on Industrial Electronics.
R. Marquardt, Modular Multilevel Converter (MMC) Technology for High-Voltage Applications.
N. Mohan, T. M. Undeland, and W. P. Robbins, Power Electronics: Converters, Applications, and Design, 3rd Edition, Wiley.

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