Dual-Active-Bridge Converter for Galvanic Isolation in Energy Storage
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Solution Overview
Problem
Existing energy storage systems face scalability limitations when paralleling batteries, requiring precise voltage matching and specific cell types, which restricts system flexibility and makes them vulnerable to failure due to the weakest link.
Innovation Solution
The implementation of a power electronics interface with galvanic isolation allows for the use of different cell types, ages, and voltages, enabling independent operation of cells within a DC microgrid, eliminating failure propagation and enhancing scalability by using a dual-active-bridge converter and DC/DC converters for efficient power management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If batteries are paralleled to increase capacity, then the energy storage capacity increases, but the system requires precise voltage matching and complex management strategies
Solution Approach 1:
The system segments the battery array into multiple independent modules, each with its own DC/DC converter. This segmentation allows each module to operate independently with its own voltage characteristics, eliminating the need for precise voltage matching between parallel batteries while reducing overall system complexity.
Solution Approach 2:
DC/DC converters are introduced as intermediary devices between individual battery modules and the common DC bus. These converters act as mediators that isolate voltage differences between modules, allowing batteries with different voltages, chemistries, and ages to be connected without requiring complex balancing strategies.
2Quantity of substance
If batteries are paralleled electrically, then the energy storage capacity increases, but the system is limited by the weakest link and vulnerable to failure propagation
Solution Approach 1:
The system divides the battery array into electrically isolated modules, each controlled by its own DC/DC converter. This segmentation ensures that a failure in one module does not propagate to other modules, as each module operates independently with its own protection and control circuitry.
Solution Approach 2:
The system incorporates individual DC/DC converters for each battery module that provide electrical isolation and protection before failures can propagate. These converters act as protective barriers that prevent fault propagation, allowing the system to tolerate individual cell or module failures without taking the entire system offline.
3Reliability
If precise voltage matching is required for parallel batteries, then the system can operate reliably, but the scalability is significantly limited
Solution Approach 1:
DC/DC converters serve as intermediary devices that decouple the voltage matching requirement from the parallel battery configuration. Each converter independently regulates its module's voltage, allowing batteries with different voltage characteristics to be connected to the common DC bus without compromising reliability.
Solution Approach 2:
The system allows for parameter changes in battery modules (voltage, capacity, chemistry, age) by using DC/DC converters that can adapt to different module characteristics. Each converter is configured to match its specific module's parameters, enabling scalable system expansion with diverse battery types without requiring uniform voltage matching across all 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
This approach enables the creation of scalable energy storage systems that can handle diverse cell types and ages, ensuring system reliability and efficiency by isolating cells and allowing for independent failure, thus preventing a single cell failure from taking down the entire system.
Implementation Method 1
dual-active-bridge converter
Data Source
AI summary
An energy storage device includes: a number of cells; and a dual-active-bridge converter connected to the cells, wherein the cells are floating relative to the system and are galvanically isolated therefrom. The energy storage device can be included in an energy storage system that includes: a grid tie unit comprising at least one DC/AC converter; and multiple pods connected to the grid tie unit, each pod including: a number of cells; and a power electronics unit, wherein the cells are floating relative to the system and are galvanically isolated therefrom.