Lithium Ion Battery Charge Control for Wind Power Reliability
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Solution Overview
Problem
Wind power generation systems face challenges in controlling charging currents due to the time lag in adjusting windmill blade pitch angles, leading to potential lithium metal deposition and performance degradation in lithium ion storage batteries.
Innovation Solution
An electric storage device with a control unit that calculates a charge complete voltage by accounting for battery voltage differences and no-load characteristics to determine when to complete charging, preventing lithium metal deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If charging current control is implemented using instantaneous response methods, then lithium metal deposition can be prevented, but the system cannot be applied to wind power generation due to time lag in blade pitch angle adjustment
Solution Approach 1:
The control unit calculates the charge complete voltage in advance based on the relationship between battery voltage and charge rate, before lithium metal deposition occurs. This preliminary calculation allows the system to proactively determine when to stop charging, compensating for the time lag in windmill blade pitch angle adjustment and preventing lithium deposition even though instantaneous current control is not feasible.
2Reliability
If charge control is delayed due to time lag in windmill response, then lithium metal deposition occurs on the negative electrode, but instantaneous control is not feasible for wind power generation
Solution Approach 1:
The control unit continuously monitors the battery voltage during charging and compares it against the pre-calculated charge complete voltage threshold. This feedback mechanism allows the system to detect when the battery voltage approaches the critical level where lithium deposition would occur, and stop charging at the appropriate moment, compensating for the inherent time lag in wind power generation control.
3Productivity
If the battery voltage reaches a high value during charging, then charging efficiency is improved, but the risk of lithium metal deposition increases
Solution Approach 1:
The control unit dynamically adjusts the charging process by monitoring battery voltage and comparing it to the charge complete voltage threshold. When the battery voltage reaches this threshold, indicating high charging efficiency but also increased lithium deposition risk, the system automatically stops charging. This parameter-based control allows the system to maximize charging efficiency while preventing harmful lithium metal deposition.
Data Source
AI summary
Provided are: an electric storage device having improved reliability in charging a storage battery; and a charging method. This electric storage device is provided with: an SOC calculation section which calculates a charge rate when a battery voltage reached a predetermined value, in the cases where the battery voltage reached the predetermined value when a lithium ion storage battery is being charged; a voltage difference calculation section, which calculates a battery voltage difference corresponding to a difference between the charge rate and a charge rate at which lithium is deposited; a charge complete voltage calculation means, which calculates a charge complete voltage by adding the voltage difference to the battery voltage obtained when the battery voltage reached the predetermined value; and a charge control means, which completes the charging of the lithium ion storage battery in the cases where the battery voltage reached the charge complete voltage.