Multi-Level Dual Active Bridge Energy Storage Module
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Solution Overview
Problem
Conventional energy storage modules in electrical systems, such as those in aircraft, are bulky, heavy, and complex due to the need for multiple low-voltage energy cells, which complicates voltage regulation on direct current buses and increases size and weight.
Innovation Solution
The implementation of a multi-level dual active bridge (ML-DAB) energy storage module assembly with bi-directional DC/AC converters, isolation transformers, and power filters, allowing for efficient current sourcing and absorption, and voltage regulation on DC buses, reducing the need for separate modules and simplifying interfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple low-voltage energy cells are stacked to achieve required voltage levels, then voltage regulation capability is improved, but system weight increases
Solution Approach 1:
The patent divides the energy storage system into modular units, each containing a single low-voltage energy cell combined with a DC-DC converter. Multiple modular units are connected in parallel to achieve the required voltage level, replacing the conventional approach of stacking cells in series. This segmentation allows each module to operate independently and contributes to weight reduction through optimized power electronics design.
Solution Approach 2:
The patent changes the voltage conversion approach from direct series stacking to parallel connection with active DC-DC conversion. By using pulse-width modulation (PWM) controlled converters, the system achieves the required voltage levels through electronic parameter transformation rather than physical cell stacking, resulting in reduced weight and improved regulation capability.
2Power
If multiple low-voltage energy cells are stacked to achieve required voltage levels, then voltage regulation capability is improved, but device complexity increases
Solution Approach 1:
The patent designs a universal modular interface where each energy cell is paired with an identical DC-DC converter module. This standardized multi-functional design allows the same modular unit to serve multiple purposes: energy storage, voltage regulation, and power conversion. The universal interface simplifies system integration and reduces overall complexity compared to custom-designed cell stacks.
Solution Approach 2:
The DC-DC converter acts as an intermediary between the low-voltage energy cell and the high-voltage DC bus. This intermediary component manages the voltage transformation and power flow control, eliminating the need for complex direct connections between multiple cells and the bus, thereby simplifying the overall interface architecture.
3Reliability
If conventional energy storage modules are used to smooth voltage changes, then power quality is improved, but volume increases
Solution Approach 1:
The patent replaces the conventional mechanical/electrical approach of using large capacitor banks or inductor-based voltage smoothing circuits with an electronic control system based on PWM-controlled DC-DC converters. This substitution achieves superior voltage regulation and power quality improvement in a much more compact form factor by using high-frequency switching and advanced control algorithms.
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
This solution results in a more compact, lighter, and less complex energy storage system capable of effectively regulating voltage on DC buses, meeting high power and energy storage requirements with reduced weight and volume, and enabling a single design to cater to various applications.
Implementation Method 1
a bi-directional isolation transformer connected to the bi-directional DC/AC converter
Data Source
AI summary
An energy storage module (ESM) assembly includes an ESM having an energy source and a multi-level dual active bridge (ML-DAB). The ML-DAB is connected to the energy source to source current therefrom, or send current thereto, or both. A system architecture includes the ESM assembly having an ESM with an energy source, and a ML-DAB connected to the energy source to source current therefrom, or send current thereto, or both. The system architecture includes a DC bus connected to the ESM assembly.