Battery Module Internal Relays for Safe High-Voltage Isolation
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Solution Overview
Problem
High voltage and high current battery packs in vehicles pose safety hazards during assembly, service, and adverse events due to potential fires and explosions, and existing modular designs are impractical for handling and servicing without specialized training and equipment, with risks of energy loss and capacity degradation from defective cells.
Innovation Solution
A battery module design with series-connected cells electrically isolated from the enclosure, featuring normally-open relays that connect the cells to external terminals only when activated, ensuring safe handling and minimizing hazards by preventing short circuits and allowing for graceful degradation and easy replacement of failed modules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If groups of cells are connected in parallel to achieve desired current capability, then current capability is improved, but the risk of fire and explosion increases due to large energy release from shorts across external terminals
Solution Approach 1:
The battery pack is divided into multiple modules, each containing series-connected cells. This segmentation isolates the high current capability within each module while the overall pack achieves desired voltage through series connection of modules, reducing the energy release risk in any single module compared to a monolithic parallel configuration.
Solution Approach 2:
Relays are introduced as intermediary components between the cells and external terminals. These relays can open the circuit to isolate cells from external connections, preventing direct shorts and the associated fire/explosion hazards while maintaining the current capability when relays are closed.
2Ease of operation
If external terminals are always connected to cells for high current capability, then ease of operation is improved, but safety deteriorates due to potential shorts releasing large amounts of energy
Solution Approach 1:
The connection between cells and external terminals is made dynamic through relays that can switch between open and closed states. This allows the system to adapt between operational mode (relays closed, terminals connected) and safe mode (relays open, terminals isolated), resolving the contradiction between ease of operation and safety.
Solution Approach 2:
Relays are positioned to prevent harmful shorts before they can occur. By providing a controllable open circuit state, the relays preemptively block potential short circuit paths, addressing the safety concern before it manifests while maintaining operational connectivity when needed.
3Reliability
If modules are designed with series-connected cells and internal relays for safety, then reliability is improved, but device complexity increases due to additional relays and isolation mechanisms
Solution Approach 1:
The battery system is segmented into modular units, each with its own relays and isolation mechanisms. This segmentation distributes the complexity across multiple independent modules rather than requiring a single complex safety system, making the overall system more manageable and potentially more reliable through redundancy.
Solution Approach 2:
The relays serve multiple functions: they enable/disable current flow, provide electrical isolation for safety, and potentially serve as diagnostic indicators. This multi-functionality reduces the need for separate components, offsetting some of the complexity increase with functional consolidation.
4Ease of manufacture
If a monolithic battery pack design is used, then manufacturing complexity is reduced, but adaptability deteriorates due to inability to service or replace individual modules
Solution Approach 1:
The battery system is divided into serviceable modules that can be independently replaced or serviced. This segmentation maintains manufacturing efficiency through standardized modules while enabling adaptability through modular replacement, resolving the contradiction between ease of manufacture and serviceability.
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
The solution provides a safe and fault-tolerant battery module that reduces the risk of fires and energy loss, allows for safe handling without specialized training, and enables economical servicing of high voltage packs, ensuring safety during adverse events and efficient operation.
Implementation Method 1
A first normally-open electrical relay is provided to electrically connect the positive side of the series connected cells to the positive terminal. A second normally-open electrical relay is provided to connect the negative side of the series connected cells to the negative terminal.
Data Source
AI summary
A battery module is disclosed having a plurality of series-connected battery cells contained in, and electrically isolated from, an enclosure, with a first internal relay to control connection between cells and a positive terminal, and a second internal relay to control the connection between cells and a negative terminal. A control signal input is provided to control the relays. An embodiment is disclosed wherein the relays are of distinct types. An embodiment is disclosed having an internal battery management system which controls the relays in response to a digital message. A modular battery pack is disclosed consisting of a plurality of modules connected in parallel, which can be individually and independently activated and deactivated. A method is provided for activating an individual module.