Modular Multi-Level Converter Ring Topology
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Solution Overview
Problem
Existing modular multi-level converters face inefficiencies in power exchange between modules of different taps or arms, particularly due to current ripple and nonlinear loss mechanisms, which lead to increased energy storage element aging and heating.
Innovation Solution
A modular multi-level converter topology is introduced, where individual modules are interconnected in a closed ring with taps between adjacent modules, allowing for a combination of ring and star configurations, enabling efficient power exchange between modules through controlled switching and parallel connections, thereby reducing losses and optimizing energy distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If conventional series connection of energy storage elements is used, then high voltage is achieved, but current ripple and nonlinear loss mechanisms increase
Solution Approach 1:
The patent applies dynamic switching between series and parallel connections of energy storage elements. The converter can dynamically reconfigure the connection topology based on operating conditions, switching from series connection (for high voltage) to parallel connection (for low voltage/high current), thereby optimizing performance and reducing nonlinear losses at different operating points.
Solution Approach 2:
The patent changes the electrical connection parameters (series/parallel configuration) of energy storage elements to optimize system performance. By altering the connection topology, the system can operate at different voltage and current levels, reducing nonlinear losses that occur at high current levels in conventional series-connected systems.
2Power
If high current is used for power exchange between modules, then power transfer is achieved, but energy storage element aging and heating increase
Solution Approach 1:
The patent changes the voltage level parameter for power exchange by using high-voltage series connections between modules. This allows power transfer to occur at high voltage and low current, rather than low voltage and high current, thereby reducing I²R losses and thermal heating while maintaining effective power exchange capability.
3Stress or pressure
If series connection of energy storage elements is used, then voltage is increased, but nonlinear loss mechanisms are exacerbated
Solution Approach 1:
The patent implements dynamic reconfiguration capability that allows the system to switch between series and parallel connections. This dynamic topology change enables the system to avoid sustained high-current operation that causes nonlinear losses, while still achieving high voltage when needed through temporary series connection configurations.
4Power
If conventional converter topology is used, then power conversion is achieved, but efficient power exchange between modules of different taps is limited
Solution Approach 1:
The patent segments the converter into multiple independent modules, each with its own energy storage elements. This modular architecture allows direct coupling between modules of different taps, enabling efficient power exchange without requiring high-current conventional conversion paths. Each module can operate semi-independently, improving overall system efficiency.
Data Source
AI summary
A modular multi-level converter including modules each having switching elements and at least one electrical energy storage element, wherein a first number of modules are interconnected to form a closed ring, and at least two taps are arranged between respective adjacent individual modules of the closed ring. Wherein at at least two taps respectively a second number of modules are provided as a phase module branching off from the closed ring and forming a star string comprising at least two modules, the phase module connected to the respective tap on one end and forming a phase terminal at an other end. Wherein the switching elements enable interconnection of energy storage elements of adjacent modules, as a result of which between two adjacent phase terminals a voltage difference is provideable, which is regulatable by a control unit in accordance with a polyphase rotating field profile. Furthermore, the present invention relates to a polyphase system and a method for efficient power exchange between modules.