Battery Control Device Current Detection Error Correction
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Solution Overview
Problem
The existing method for obtaining a correction value for battery current detection errors requires selecting two time points with equal SOC, but this is problematic due to the probability of SOC equality not being guaranteed.
Innovation Solution
A battery control device that includes a current detection unit, a closed-circuit voltage detection unit, an open-circuit voltage calculation unit, a time-point setting unit, a current integral amount calculation unit, and a current correction unit, which sets time points based on voltage differences and calculates a current correction amount to correct detection errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two time points with equal SOC are selected to calculate current correction value, then current detection accuracy is improved, but the probability of finding such time points becomes unreliable
Solution Approach 1:
The patent changes the selection criterion from SOC equality to voltage difference equality. Instead of requiring equal SOC values at two time points, the system selects time points where the voltage difference (absolute value of closed-circuit voltage minus open-circuit voltage) is equal or substantially equal. This parameter substitution makes the time point selection reliable and achievable in practical operation.
Solution Approach 2:
The patent uses voltage difference as a surrogate indicator instead of directly measuring and comparing SOC values. Voltage is an easily measurable electrical parameter that can serve as a reliable proxy for SOC comparison, avoiding the complexity and unreliability of direct SOC equality verification.
2Measurement precision
If current correction is performed using temporal integral method, then current accuracy is improved, but the complexity of the correction process increases
Solution Approach 1:
The patent performs preliminary calculation of voltage differences and identifies suitable time point pairs in advance. By pre-selecting time points where voltage differences are equal, the system simplifies the subsequent current correction calculation, making the overall process more manageable and less complex.
Solution Approach 2:
The patent introduces voltage difference as an intermediary parameter to facilitate current correction. Instead of directly comparing SOC values or performing complex temporal integral calculations, the system uses voltage difference equality as a mediator to identify appropriate time points for correction, simplifying the overall correction methodology.
Data Source
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AI summary
Provided is a battery control device capable of obtain a charging/discharging current with a high accuracy. The battery control device 120 includes a time-point setting unit 153 which calculates a voltage difference dV obtained by subtracting a calculated open-circuit voltage OCV from a measured closed-circuit voltage CCV, and sets first and second time points at which an absolute value of the voltage difference dV becomes equal to or less than a predetermined value and an absolute value of a difference in the open-circuit voltage OCV becomes equal to or less than a predetermined value. The battery control device 120 further includes the current integral amount calculation unit 154 to obtain the current integral amount ∫I(t) which is an integral amount with time of the current flowing through the cell 111 from the first time point to the second time point, the current correction amount calculation unit 156 which calculates the current error contained in a detection signal output by the current detection unit and sets the current error as the current correction amount on the basis of the current integral amount and a time from the first time point to the second time point, and the current correction unit 131 which corrects the detection signal using the current correction amount.