Battery Degradation Estimator Using Load and Temperature Feedback
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Solution Overview
Problem
Existing charge-discharge control devices for secondary batteries only correct reference voltage values based on the estimated number of charge-discharge cycles, which may not adequately suppress battery degradation due to current levels during charging and discharging.
Innovation Solution
A degradation estimator for energy storage devices that calculates a temporary power decrease rate based on maximum load and temperature, adjusting current input and output to maintain this rate below a predetermined value, thereby suppressing temporary power decrease and preventing its transition to permanent power decrease.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reference voltage values are corrected only based on the estimated number of charge-discharge cycles, then the control system is simple to implement, but battery degradation is not adequately suppressed due to ignoring current levels during charging and discharging
Solution Approach 1:
The patent changes the parameters used for degradation estimation from only cycle count to include both cycle count and current levels. The degradation estimation unit calculates temporary power decrease rates based on maximum load and temperature, then estimates overall degradation by combining cycle-based and current-based degradation rates, thereby achieving more comprehensive degradation suppression
Solution Approach 2:
The patent replaces simple cycle-counting mechanics with a more sophisticated degradation estimation mechanism that incorporates electrical parameters (current, power) and thermal parameters (temperature). This substitution enables the system to account for the actual stress conditions on the battery rather than just the number of cycles
2Duration of action of stationary object
If the temporary power decrease rate is strictly controlled to prevent permanent power decrease, then battery lifespan is extended, but the operating flexibility and power output capability are reduced
Solution Approach 1:
The patent implements dynamic control by continuously monitoring the temporary power decrease rate and adjusting the current command accordingly. The control system dynamically balances power output requirements with degradation prevention by modulating the current based on real-time battery state, allowing flexible operation within safe boundaries
Solution Approach 2:
The patent employs feedback control where the degradation estimation unit continuously estimates the temporary power decrease rate based on maximum load and temperature, and the control unit uses this feedback to adjust the current command to the power storage device, ensuring the temporary power decrease rate remains controlled while maintaining operational flexibility
Data Source
AI summary
It is an object of an embodiment to provide a degradation estimator for an energy storage device, configured to estimate degradation of the energy storage device, an energy storage apparatus, an input-output control device for the energy storage device, and a method for controlling input and output of the energy storage device. The embodiment includes estimating a temporary power decrease rate of the energy storage device in accordance with at least one of an average load, a maximum load, and a ΔSOC obtained from detected current of the energy storage device and detected temperature of the energy storage device.