Battery Formation Current Control Using Sensor Transfer Functions
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing battery formation and testing processes face challenges in accurately controlling high currents and voltages during battery formation and testing, particularly in maintaining precision within ±0.05% of target values, due to temperature-related issues with current and voltage sensors.
Innovation Solution
A battery formation/testing controller determines the transfer function of current and voltage sensors, allowing for accurate measurement and control of DC energy signals by compensating for sensor changes and non-linearities, enabling the use of lower-cost sensors with less stable temperature coefficients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-accuracy current sensors with stable temperature coefficients are used, then measurement precision is improved, but device cost increases
Solution Approach 1:
The system dynamically adjusts the transfer function parameters based on temperature measurements. By monitoring temperature changes and updating the transfer function accordingly, the system compensates for sensor drift without requiring expensive high-stability sensors, thus achieving accurate measurements with lower-cost components
Solution Approach 2:
The patent replaces hardware-based temperature compensation (using inherently stable sensors) with a software-based transfer function correction system. The microcontroller updates the transfer function based on temperature measurements, substituting physical sensor stability with computational compensation
2Measurement precision
If regular transfer function determination is performed, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The system performs transfer function determination periodically based on temperature thresholds or time intervals rather than continuously. This periodic updating maintains measurement accuracy while minimizing the time lost to calibration operations
Solution Approach 2:
The transfer function is determined in advance during initialization or before temperature excursions occur, preparing correction data beforehand. This preliminary action ensures accurate measurements are ready when needed without delaying the actual battery formation process
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The disclosure relates to accurately determining a DC energy signal, such as a DC current or DC voltage, which may be particularly useful when controlling a formation/testing current of a battery cell during formation and/or testing. In the battery formation/testing context, a current sensor is used to measure the current of the battery cell, which is used as a feedback signal for controlling the current to achieve a target current. The transfer function of the current sensor is used to improve the accuracy of the current measurement. Because the transfer function can be regularly determined during formation/testing, a lower-cost current sensor with relatively poor temperature coefficient may be used. Any change in the gain of the current sensor may be detected by the transfer function determination and corrected for. Therefore, high current control accuracy may be achieved at lower cost.