Battery Module Galvanic Isolation Without Isolated DC/DC Converters
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Solution Overview
Problem
Existing railway electrical energy storage systems require costly and bulky isolated DC/DC converters to ensure galvanic isolation between high and low voltage components, which is not necessary when the voltage at the inlet of the DC/DC converter is below 1,500 V, leading to inefficiencies in size, weight, and cost.
Innovation Solution
The electrical energy storage system integrates galvanic isolation means within each module, eliminating the need for a separate DC/DC converter or allowing the use of a non-isolated converter, by providing isolation between high and low voltage components through a battery management system with an isolation board and spacers, ensuring compliance with regulations for voltage levels up to 3,000 V.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an isolated DC/DC converter is used to ensure galvanic isolation between high and low voltage components, then safety and regulatory compliance are improved, but device complexity, size, weight, and cost increase significantly
Solution Approach 1:
The energy storage device is divided into multiple independent modules, each equipped with its own battery management system that provides galvanic isolation. This segmentation distributes the isolation function across modules rather than requiring a single centralized isolated converter, reducing overall system complexity while maintaining safety
Solution Approach 2:
The battery management system performs multiple functions: cell monitoring, charge control, and galvanic isolation. By making the BMS multi-functional, the patent eliminates the need for separate isolated DC/DC converters, reducing device complexity, size, and cost while maintaining the required safety isolation
2Device complexity
If a non-isolated DC/DC converter is used to reduce size and cost, then device complexity is reduced, but galvanic isolation safety and regulatory compliance deteriorate
Solution Approach 1:
An isolation board is introduced as an intermediary component within the battery management system. This isolation board provides the necessary galvanic isolation between high and low voltage sides, enabling the use of non-isolated DC/DC converters while maintaining safety requirements
3Device complexity
If the voltage at the inlet of the DC/DC converter is kept below 1,500 V to avoid isolation requirements, then galvanic isolation requirements are simplified, but adaptability to high voltage railway systems deteriorates
Solution Approach 1:
The patent changes the isolation implementation approach from voltage-level dependent to architecture-dependent. By implementing isolation at the module/BMS level rather than at the DC/DC converter level, the system can adapt to various voltage levels (including high voltage 3,000 V railway systems) without being constrained by voltage-threshold-based isolation requirements
Data Source
AI summary
An electrical energy storage system having at least one electrical energy storage device (1) with at least one module (100) that has cells (101) for storing electrical energy, wherein the electrical energy storage system has galvanic isolation element configured to provide galvanic isolation between internal conductive elements of the at least one module (100) configured to be connected to high voltage and internal conductive elements of the at least one module (100) configured to be connected to low voltage and/or ground.