Parallel Battery Short Circuit Protection via Segmented Switching
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Solution Overview
Problem
High-power d.c. voltage sources using lithium-ion electrochemical accumulators face challenges in managing high short-circuit currents, which exceed the breaking capacity of conventional electro-mechanical circuit-breakers, making it difficult to maintain safety and feasibility in electrical installations, especially in high-power applications.
Innovation Solution
An electrical installation is designed with a d.c. voltage source comprising electrochemical accumulator batteries connected in parallel, where the voltage source is connected in series with a circuit-breaker of lower breaking capacity. A control circuit detects when the current exceeds the tripping current of the circuit-breaker and strategically opens or closes switches to ensure the current through the circuit-breaker is within its tripping and breaking capacity, allowing for rapid response and safe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-power d.c. voltage sources use lithium-ion electrochemical accumulators connected in parallel, then energy storage capacity is improved, but short-circuit current exceeds the breaking capacity of conventional circuit-breakers
Solution Approach 1:
The patent divides the parallel battery system into multiple groups, each equipped with its own circuit-breaker. This segmentation allows each circuit-breaker to handle a portion of the total short-circuit current, making the protection system feasible with conventional breaking capacities while maintaining high overall energy storage capacity through the parallel configuration of multiple battery groups.
2Reliability
If electro-mechanical circuit-breakers with high breaking capacity are used, then short-circuit protection is improved, but cost and device complexity increase significantly
Solution Approach 1:
Instead of using a single complex high-capacity circuit-breaker, the patent segments the protection function across multiple standard-capacity circuit-breakers, each protecting a specific battery group. This approach reduces individual device complexity and cost while collectively providing adequate short-circuit protection for the entire high-power system.
3Quantity of substance
If numerous electrochemical accumulators are connected in parallel to achieve high capacity, then energy storage is improved, but the internal resistance decreases causing higher short-circuit currents
Solution Approach 1:
The patent segments the parallel battery configuration into multiple groups with individual circuit-breakers. This segmentation controls the short-circuit current path, ensuring that each circuit-breaker handles only a portion of the total current, thereby managing the harmful effect of high short-circuit currents while preserving the high capacity benefits of parallel connection.
Solution Approach 2:
Circuit-breakers serve as intermediary protective devices between the parallel battery groups and the electrical installation. These intermediaries limit and control the short-circuit current flow, preventing excessive currents from reaching the electrical installation while allowing the batteries to maintain their high capacity through parallel connection.
Data Source
AI summary
An electrical installation includes a circuit-breaker having a breaking capacity PdC and a tripping current Is, an ammeter measuring the current, and a DC voltage source comprising batteries connected in parallel and connected in series with the circuit-breaker. The sum of the short-circuit currents of the batteries connected in parallel is higher than the breaking capacity PdC of the circuit-breaker. A plurality of the batteries each includes a respective switch capable of opening a connection between the battery of the same and the circuit-breaker. The electrical installation also includes a control circuit to detect that the current passing through the circuit-breaker is higher than the tripping current Is and to control the opening of a plurality of the switches in order to apply, through the circuit-breaker, a current higher than the tripping current Is of the same and lower than the breaking capacity PdC of the same.