Patent
Modular Multilevel Converter
Problem Statement
- Complexity of Voltage Clamping: Conventional multilevel converters require multiple voltage sources or dc-links (often electrolytic capacitors) to clamp voltage at lower levels. This complexity increases system design intricacy and operational costs.
- Cost and Longevity Concerns: The use of numerous electrolytic capacitors as dc-links not only raises the overall cost of the converter but also compromises its longevity due to the limited lifespan and reliability of electrolytic capacitors.
- Application Limitations: While modular structures enhance system reliability and reduce voltage and current distortion, they may not be cost-effective or suitable for all high-power applications due to the aforementioned drawbacks.
Lab Setup of MMC
Abstract
This invention introduces a Modular Multilevel Converter (MMC) designed for medium power applications. The MMC consists of a specific number of modules per phase, where each module includes two switches. These modules are interconnected to a shared dc-link, facilitating connection to one or more dc sources. Additionally, each phase of the MMC incorporates at least one coupled inductor to link the modules to the converter's output terminal. This configuration enhances voltage waveform resolution and reduces harmonic distortion, making the MMC suitable for diverse applications requiring precise voltage control and operational reliability in medium power application.
Uniqueness of the Solution
- Modularity: MMCs are structured with multiple modules per phase, each comprising pairs of switches connected to a common dc-link. Voltage Levels: They generate multilevel voltage outputs using parallel-connected modules, reducing harmonic content and enhancing grid compatibility.
- Coupled Inductors: Each phase integrates coupled inductors to mitigate out-of-phase harmonic components and ensure smooth output voltage.
- Fault Tolerance: Capable of operating with disabled modules without significant impact on overall performance, ensuring robustness in varying operational conditions.
Prototype Details
- The MMC has been tested with three cells per phase and a DC-link voltage of 200V. A three-phase inductor with an inductance value of 5 mH, increased to 20 mH by reducing air-gaps, was used as the coupled inductor.
- The waveforms demonstrated that the output voltage of each module has two levels, while the phase output voltage has four levels.
- The currents in the windings of the coupled inductor were almost equal in magnitude, validating the equal distribution of fundamental frequency currents.
- The MMC produced the rated output voltage even after disabling faulty modules.
Current Status of Technology
- A prototype has been developed and validated in lab environment.
- The MMC produced the rated output voltage even after disabling faulty modules.
Technology readiness level
4
Societal Impact
- Energy Efficiency: By reducing voltage and current distortions and optimizing system performance, MMCs contribute to energy conservation and reduced electricity consumption.
- Grid Stability: Improved power quality indices ensure stable and reliable electricity supply, benefiting industries, residential areas, and essential services dependent on uninterrupted power.
- Environmental Benefits: Lower switching frequencies and reduced losses enhance overall energy efficiency, indirectly contributing to lower carbon emissions.
- Various Applications such as Electric Vehicle Charging, Renewable Energy Integration, and Industrial Drives for variable speed control.
Relevant Industries, Domains and Applications
Electrical and Power Electronics Converter Manufacturing, Power, Energy, Renewable Energy
Applications or Domain
- Renewable Energy Integration: MMCs are used in grid-connected solar and wind power systems for efficient power conversion and grid synchronization.
- Electric Vehicle Charging: MMCs facilitate fast and efficient charging stations for electric vehicles, supporting high-power DC charging.
- Industrial Drives: Applied in industrial motor drives for variable speed control and energy efficiency improvements.
Application Number
201821047042
Filing Date
Grant Number
421226
Grant Date
Assignee(s)
Indian Institute of Technology Bombay
IP Themes
Faculty
Department
**This IP is owned by IIT Bombay**