Battery Formation Controller Transfer Function Calibration

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Solution Overview

Problem

High current and voltage control during battery formation and testing requires accurate measurement and stable sensors, but high currents lead to temperature increases, making it challenging to maintain accuracy with existing sensors, especially when dealing with large numbers of batteries that need to operate similarly.

Innovation Solution

A battery formation/testing controller determines the transfer function of a current or voltage sensor, allowing for the use of lower-cost sensors with less stable temperature coefficients by detecting and correcting for changes, ensuring high accuracy in current and voltage control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If high-accuracy current sensors with stable temperature coefficients are used, then measurement precision is improved, but device cost increases

Engineering Contradiction:

Improvecurrent measurement accuracyVSAvoiddevice cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The transfer function of the current sensor is determined in advance during battery formation or testing, before the sensor is used for precise current measurement. This preliminary characterization captures the sensor's gain and offset parameters, which are then stored and used for continuous correction during operation, eliminating the need for expensive high-precision sensors

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors the current sensor output and applies real-time correction using the pre-determined transfer function. The correction process adjusts the measured current values based on the stored gain and offset parameters, maintaining measurement accuracy without requiring expensive hardware

Inventive Principle:

Principle #23Feedback

2Productivity

If high currents are applied during battery formation/testing, then productivity is improved, but temperature increases making measurement stability difficult

Engineering Contradiction:

Improveformation/testing speedVSAvoidsensor temperature stability

Core Design Contradiction:

ProductivityVSTemperature

Solution Approach 1:

The transfer function characterization is performed once at the beginning, capturing the sensor's electrical parameters (gain and offset) before temperature-induced drift occurs. This preliminary measurement allows the system to compensate for subsequent temperature variations without requiring continuous recalibration during high-current operation

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses the pre-determined transfer function to continuously correct current measurements during high-current formation/testing operations. This feedback mechanism maintains measurement accuracy despite temperature fluctuations caused by high current loads

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS11435404B2Battery formation/testing

Publication Date: 2022.09.06 ANALOG DEVICES INT UNLTD CO

AI summary

Techniques for controlling a current of a battery cell during formation and/or testing are described. 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.