Battery Charge Time Calculation Using Current Threshold Segmentation
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Solution Overview
Problem
The battery terminal voltage varies with charge current, making it difficult to accurately calculate and display the remaining charge time using maps showing the relationship between State of Charge (SOC) and terminal voltage.
Innovation Solution
A charge control device and method that calculates the remaining charge time by subtracting the elapsed time from when the charge current falls below a predetermined threshold value, allowing for accurate estimation of the remaining charge time, especially when the SOC does not vary greatly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the remaining charge time is calculated using a map showing the relationship between SOC and terminal voltage, then the calculation method is simple, but the accuracy is low due to voltage variation with charge current
Solution Approach 1:
The patent segments the charging process into two distinct phases: constant current charging (when charge current is above threshold) and constant voltage charging (when charge current falls below threshold). Different calculation methods are applied to each phase - map-based calculation for the first phase and elapsed time subtraction for the second phase - thereby resolving the contradiction between simplicity and accuracy by matching the calculation method to the charging phase characteristics
Solution Approach 2:
The patent dynamically switches between two different calculation methods based on the charge current threshold. When the battery transitions from constant current to constant voltage charging, the system dynamically changes from using the SOC-voltage map to using elapsed time subtraction, ensuring accurate remaining charge time calculation throughout the entire charging process while maintaining computational efficiency
2Measurement precision
If the remaining charge time is calculated based on SOC variation, then the method works well when SOC changes significantly, but the accuracy deteriorates when the battery is near full charge and SOC change is small
Solution Approach 1:
The patent dynamically adapts the calculation method based on the charging phase. During constant current charging, it uses map-based calculation; during constant voltage charging (near full charge), it switches to elapsed time subtraction. This dynamic adaptation ensures high accuracy throughout the entire charging range, particularly improving precision when SOC changes are minimal near full charge
Solution Approach 2:
The patent changes the calculation parameter from SOC-based (map lookup) to time-based (elapsed time subtraction) when the charge current falls below the threshold. This parameter change allows the system to maintain accurate remaining charge time calculation even when SOC variation becomes negligible near full charge, resolving the accuracy issue in the high SOC region
Data Source
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AI summary
A charge control device that charges a battery (20) using a power output from a charger (10), wherein detecting means for detecting a voltage and current of the battery (20), charge state (SOC) calculation means for calculating the SOC of the battery using the detected values of the detecting means, and charge time calculation means for calculating, on the basis of the SOC calculated by the SOC calculation means, the remaining charge time of the battery (20) till the SOC of the battery (20) reaches a prescribed SOC, are provided. When the charge current falls below a predetermined current threshold from above the current threshold below the threshold, the charge time calculation means calculates the remaining charge time by subtracting from the charge time calculated when the charge current has fallen below the current threshold a value reflecting an elapsed time from when the charge current falls below the current threshold value