Battery Power Limit Management via Dynamic SOC Thresholds
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Solution Overview
Problem
As batteries age, their power capability decreases, leading to reduced power limits across the entire state of charge (S.O.C.) operating range, which can be unnecessarily restrictive, as existing methods often reduce power limits uniformly rather than optimizing them within the S.O.C. range.
Innovation Solution
A method that adjusts the minimum and maximum operating S.O.C. ranges and discharge/charge power limits based on the battery's power capability, allowing higher power limits by determining new S.O.C. thresholds where full power is available, and setting these limits to ensure optimal power utilization without exceeding the battery's capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the entire power limit curve is reduced uniformly to ensure it remains under the power capability curve at every S.O.C., then battery safety is maintained, but power limits are significantly reduced over the entire S.O.C. operating range when higher power limits might be available in some ranges
Solution Approach 1:
The patent applies local quality by allowing different power limit reductions at different S.O.C. points. Instead of uniformly reducing the entire power limit curve, the method selectively reduces power limits only at specific S.O.C. points where the battery power capability has degraded below the original power limit curve, while maintaining higher power limits in ranges where capability remains sufficient.
Solution Approach 2:
The patent changes the parameter approach from a fixed uniform reduction to a dynamic selective reduction based on actual battery capability measurements. The power limit curve is adjusted by comparing actual battery power capability at each S.O.C. point against the original power limit curve, and reductions are applied only where necessary to maintain safety while preserving performance elsewhere.
2Reliability
If the minimum operating S.O.C. is increased to ensure full discharge power availability, then power reliability is improved, but the operating S.O.C. range is reduced
Solution Approach 1:
The patent applies dynamics by making the minimum operating S.O.C. threshold adjustable rather than fixed. The threshold is dynamically determined based on the battery's actual power capability at different S.O.C. points, allowing the system to adapt the operating range to match actual battery performance while ensuring full discharge power availability when needed.
Data Source
AI summary
A method for managing power limits for a battery includes the step of increasing a minimum operating state of charge after an initial power capability has decreased to the point where a predefined full discharge power is not available at an initial minimum operating state of charge. The increased minimum operating state of charge can be chosen such that the full discharge power is available. The increased minimum state of charge may not be chosen to provide the full discharge power if the increased minimum state of charge is greater than a maximum low limit state of charge.