Charge Time Calculation Using Temperature Segmentation
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Solution Overview
Problem
Existing charge-time calculation methods have low accuracy, particularly when battery temperature and surrounding conditions are not accurately accounted for during charging.
Innovation Solution
A method that calculates the charge time by determining a first timing when the battery temperature reaches a predetermined limit, then calculates a second charge time based on the battery state at that timing and the charge power, and adds this to the first charge time to obtain the total charge time, using a charge controller that manages battery state and power input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple voltage-based SOC determination method is used, then the calculation process is simple, but the charge-time calculation accuracy is low
Solution Approach 1:
The charging process is segmented into multiple phases based on battery temperature thresholds. The charge-time calculation is divided into: (1) time to reach limit temperature at first charge power, (2) time to reach SOC 100% after temperature limit is reached. This segmentation allows different calculation methods for different charging stages, improving overall accuracy while maintaining computational efficiency.
Solution Approach 2:
The method performs preliminary calculation of the time required for battery temperature to reach the limit temperature before calculating the remaining charge time. By determining this first timing point in advance, the system can accurately account for temperature-dependent charging effects, thereby improving charge-time prediction accuracy without significantly increasing computational complexity.
2Device complexity
If battery temperature and surrounding conditions are not accounted for, then the calculation is simpler, but the charge-time estimation is inaccurate
Solution Approach 1:
The calculation method applies different charge power values based on local temperature conditions. When battery temperature reaches the limit temperature, the system switches from first charge power to second charge power. This local adaptation to temperature conditions ensures accurate charge-time estimation across varying thermal environments without requiring a completely complex calculation framework.
Solution Approach 2:
The method dynamically changes the charge power parameter based on battery temperature. By monitoring temperature and adjusting charge power between two distinct levels, the system accurately reflects real-world charging behavior where high temperature reduces charging rate. This parameter change approach improves estimation accuracy while keeping the calculation methodology practical and implementable.
Data Source
AI summary
A chargeable power of the battery is calculated based on a voltage and charge upper-limit voltage of a battery; the chargeable power and outputtable power of the charger are compared and a lower power is calculated as a first charge power; a timing that the battery temperature reaches a predetermined limit is calculated as a first timing; based on the temperature, surrounding temperature, and charge current when charging with the first charge power, a second charge power limited according to the battery temperature is calculated; by referencing a map, a charge time that comes after the first timing is calculated as a second charge time based on the state of the battery when the first timing is reached and the second charge power; and time obtained by adding the second charge time to the first charge time until the first timing is reached is calculated as the total charge time.