Hybrid Modular Multilevel Converter With Integrated Galvanic Isolation
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Solution Overview
Problem
Modular multilevel converters (MMCs) and hybrid modular multilevel converters (HMMCs) lack built-in galvanic isolation, necessitating the use of large and heavy external transformers, which compromises power density, weight, and cost, particularly in motive applications like marine propulsion.
Innovation Solution
Incorporate dual active bridge converters with built-in galvanic isolation into the submodules of MMCs and HMMCs, enabling compact and modular designs that maintain power quality and scalability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an external standard stand-alone conventional fundamental frequency transformer is added to provide galvanic isolation, then galvanic isolation is achieved, but the volume and weight increase significantly
Solution Approach 1:
The patent merges the galvanic isolation function into the submodule structure by integrating a high-frequency transformer within each submodule. This combines the power conversion function with the isolation function, eliminating the need for a separate external transformer and significantly reducing overall system weight and volume.
Solution Approach 2:
The patent changes the operating frequency parameter from conventional fundamental frequency (50/60 Hz) to high frequency. This parameter change enables the use of smaller, lighter high-frequency transformers that provide the same galvanic isolation functionality while dramatically reducing weight and volume compared to conventional low-frequency transformers.
2Reliability
If an external standard stand-alone conventional fundamental frequency transformer is added to provide galvanic isolation, then galvanic isolation is achieved, but the power density decreases
Solution Approach 1:
By merging the isolation function into the submodule with an integrated high-frequency transformer, the system achieves galvanic isolation without adding external bulky components. This integration maintains compactness and preserves high power density while providing the required galvanic isolation.
Solution Approach 2:
Changing to high-frequency operation enables the use of compact high-frequency transformers with much higher power density compared to conventional low-frequency transformers. This allows the system to maintain high overall power density while achieving galvanic isolation.
3Reliability
If an external standard stand-alone conventional fundamental frequency transformer is added to provide galvanic isolation, then galvanic isolation is achieved, but the cost increases
Solution Approach 1:
The patent merges multiple functions (power conversion and galvanic isolation) into a single integrated submodule structure. This eliminates the need for separate external transformer components, reducing total component count, simplifying assembly, and lowering overall manufacturing cost while maintaining galvanic isolation functionality.
4Weight of stationary object
If the converter design is made compact and modular with built-in galvanic isolation, then volume and weight are reduced, but device complexity increases
Solution Approach 1:
The patent segments the converter into modular submodules, with each submodule containing an integrated high-frequency transformer for galvanic isolation. This segmentation allows the complex isolation function to be distributed across multiple identical modular units, making the overall system more manageable despite the increased complexity of individual modules.
Solution Approach 2:
Each submodule is designed as a universal multi-functional unit that combines power conversion and galvanic isolation capabilities. This universality means that while individual submodules are complex, they are standardized and can be replicated, which simplifies overall system design and manufacturing through repetition of proven modules.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The integrated galvanic isolation enhances power density, reduces volume and weight, and lowers costs while providing fault-handling capabilities, suitable for applications requiring compactness and reliability, such as military and Navy systems.
Implementation Method 1
dual active bridge converter including a first connection, a second connection, a third connection and a fourth connection
Data Source
AI summary
Provided are modular multilevel converter and hybrid modular multilevel converters. Each of the modular multilevel converters and hybrid modular multilevel converters include submodules. Each submodule includes a first half bridge converter, a second half bridge converter, and a dual active bridge converter having a first connection, a second connection, a third connection and a fourth connection. The first half bridge converter is interconnected with the first and second connections via a first capacitor included in the first half bridge and the second half bridge converter is interconnected with the third and fourth connections via a second capacitor included in the second half bridge.