Stacked DAHB Multilevel Converter for Stable Voltage Balancing
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Solution Overview
Problem
Multilevel power converters face challenges with complex circuit topologies and unstable voltage balancing, particularly in full-bridge modular multilevel converters (MMC) and diode-clamped, capacitor-clamped topologies, which complicate capacitor voltage balancing and increase switching devices and control complexity.
Innovation Solution
The proposed topologies utilize stackable cells with dual active half bridges (DAHB) that can be individually controlled, allowing for bidirectional AC/DC or DC/DC conversion with linear scaling and inherent capacitor voltage balancing, reducing the number of components required and maintaining voltage balance without increasing control or circuit complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If traditional multilevel power converter topologies are used, then voltage conversion capability is achieved, but circuit topology complexity increases and voltage balancing becomes unstable as the number of levels increases
Solution Approach 1:
The power converter is divided into multiple independent modular units, each capable of operating autonomously. Each module contains its own switching cells and energy storage elements, allowing the system to achieve high voltage conversion capability through series connection of modules while maintaining individual module simplicity. This segmentation prevents the overall system complexity from scaling with the number of levels.
Solution Approach 2:
The patent implements dynamic control of switching devices within each modular unit to achieve flexible voltage conversion. The switching cells can dynamically adjust their operation mode (buck, boost, or bypass) based on real-time voltage balancing requirements, enabling the system to adapt to different operating conditions without increasing structural complexity.
2Power
If the number of levels in multilevel converters is increased, then higher voltage operation is achieved, but voltage balancing stability deteriorates
Solution Approach 1:
By dividing the high-voltage system into multiple independent modular units, each module maintains its own voltage balance independently. This segmentation prevents voltage imbalance from propagating across the entire system, thereby maintaining stability even as the total number of voltage levels increases through series connection of modules.
Solution Approach 2:
The patent employs dynamic parameter adjustment in the control system, specifically modifying switching duty cycles and timing parameters in real-time to maintain voltage balance. The controller adjusts switching parameters based on feedback from voltage sensors, enabling the system to maintain stable voltage balancing across multiple levels through continuous parameter optimization.
3Adaptability or versatility
If full-bridge modular multilevel converters are used, then flexibility in capacitor voltages and balancing is improved, but the number of switching devices and control complexity increase
Solution Approach 1:
The patent segments the full-bridge converter into multiple modular units, each with simplified switching arrangements. Each module provides the necessary voltage flexibility independently, reducing the total number of switching devices required compared to a traditional full-bridge multilevel converter while maintaining equivalent adaptability.
Solution Approach 2:
Each modular unit is designed with multi-functional switching cells that can operate in different modes (buck, boost, bypass) to provide universal voltage conversion capability. This multi-functionality reduces the need for dedicated switching devices for each voltage level, thereby reducing overall device complexity while maintaining flexibility.
4Power
If diode-clamped or capacitor-clamped topologies are used, then voltage conversion is achieved, but extra attention is required to keep capacitor voltages balanced, especially as levels increase
Solution Approach 1:
The patent segments the voltage conversion function into independent modular units, each with its own capacitor voltage balancing mechanism. This segmentation isolates the control complexity within each module, making voltage balancing easier to manage compared to traditional topologies where all capacitors must be balanced simultaneously across the entire system.
Solution Approach 2:
Each modular unit incorporates self-balancing capabilities through integrated control circuits that automatically adjust switching parameters to maintain capacitor voltage balance. This self-service mechanism reduces the overall control difficulty by distributing the balancing task across multiple independent units rather than requiring centralized control of all capacitors.
Data Source
AI summary
Disclosed are methods, systems, devices, and other implementations, including a voltage converter system that includes a plurality of energy storage elements, a plurality of switching devices, each of which is in electrical communication with at least one of the plurality of the storage elements, with the plurality of storage elements and the plurality of switching devices being configured in a multi-level arrangement of multiple voltage converting cells. The system further includes a plurality of controllers to actuate one or more of the plurality of switching devices to independently control voltage levels of at least one energy storage element of the multiple voltage converting cells. In some embodiments, the cells may include an arrangement of two capacitors and an inductor that define a buck-boost converter circuit. Alternatively, the cells may have a Dual Active Half Bridge (DAHB) converter configuration with a primary side separated from a secondary side by a transformer.