Real-Time Battery Impedance Estimation During Active Operation
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Solution Overview
Problem
Existing methods for estimating the internal impedance of batteries, such as those described in the FreedomCAR manual and U.S. Patent Applications, often require the power system to be inactive, leading to infrequent impedance measurements and limitations in operational flexibility.
Innovation Solution
A method and system for real-time characterization of battery internal impedance by monitoring terminal voltages and currents during normal operation, allowing for continuous estimation of internal impedance and state of health, even when the power system is active, using information-processing devices to determine internal impedance and adjust charging and discharging strategies accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the power system is kept inactive to perform impedance measurements, then measurement accuracy is improved, but system productivity deteriorates due to infrequent measurements and operational interruptions
Solution Approach 1:
The system dynamically adapts its measurement strategy based on operating conditions. It performs impedance measurements during normal operation by detecting specific voltage and current patterns, rather than requiring the system to be static or inactive. This allows the system to maintain measurement accuracy while continuing to operate and serve its primary function.
Solution Approach 2:
The system enables continuous impedance monitoring during normal power system operation by identifying measurement opportunities within the operational cycle. Instead of interrupting operation for measurements, the system continuously monitors voltage and current and performs impedance calculations when appropriate conditions are met, maintaining both operation and measurement functionality.
2Productivity
If the power system remains active for continuous operation, then system productivity is maintained, but the ability to perform accurate impedance measurements deteriorates
Solution Approach 1:
The system uses feedback from real-time voltage and current measurements to determine when measurement conditions are appropriate. By continuously monitoring operating parameters and comparing them against criteria for accurate measurement, the system can identify optimal moments to perform impedance measurements during operation, ensuring measurement quality without sacrificing operational continuity.
Solution Approach 2:
The system prepares for impedance measurements by continuously monitoring voltage and current during normal operation. When specific patterns or conditions are detected that indicate a suitable measurement opportunity, the system is already positioned to perform the measurement immediately, eliminating the need to interrupt operation or wait for scheduled maintenance windows.
3Measurement precision
If impedance measurements are performed frequently during operation, then real-time accuracy is improved, but system complexity increases due to additional monitoring and control requirements
Solution Approach 1:
The system uses the same voltage and current sensors that are already required for normal power system operation to perform impedance measurements. By making the measurement function universal and using existing infrastructure, the system achieves real-time impedance estimation without adding dedicated measurement hardware or significantly increasing system complexity.
Solution Approach 2:
The system performs impedance measurements using its own operational data and existing control logic. By leveraging the power system's own voltage and current measurements taken for operational purposes, the system can self-determine its impedance state without requiring external measurement equipment or additional complex monitoring infrastructure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate, real-time estimation of battery internal impedance and state of health, improving operational efficiency and flexibility by allowing for continuous monitoring and adjustment of battery usage without disrupting system operation.
Implementation Method 1
As a battery ages and experiences charging and discharging cycles, the battery may physically and/or chemically change
Implementation Method 2
The internal impedance of a battery affects the maximum amount of current the battery can discharge and the maximum amount of charging current the battery can receive without driving the voltage at the battery's terminals below a minimum acceptable level or above a maximum acceptable level
Data Source
AI summary
A method for real-time characterization of a battery includes providing electric power to one or more electrical power loads, charging and discharging the battery based on power needs of the one or more electrical power loads, and monitoring for a circumstance where charging and discharging of the battery results in terminal voltage of the battery substantially equaling open-circuit voltage of the battery and recording the measured terminal voltage as a first measured voltage. The method may also include monitoring for a subsequent circumstance subsequent when charging and discharging the battery results in battery current larger than a predetermined value and recording an existing terminal voltage as a second measured voltage. The method may also include using the first and second measured voltages to determine a measured internal impedance of the battery. These actions may be performed between startup and shutdown of the power system.