AC Battery Heating With In-Situ Impedance Feedback Control
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Solution Overview
Problem
Existing battery heating systems lack accurate impedance and temperature measurement capabilities, leading to inefficient thermal control and potential overheating or underheating issues.
Innovation Solution
A battery heating system that applies an alternating current (AC) to heat the battery system while periodically performing impedance measurements using electrochemical impedance spectroscopy (EIS) to maintain a desired temperature rise rate, adjusting the AC heating current based on measured impedance and temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If periodic impedance measurements are performed during battery heating, then measurement precision is improved, but heating rate control deteriorates due to interruption of heating current
Solution Approach 1:
The patent implements periodic impedance measurements at specific time intervals during the battery heating process. The measurement timing is strategically selected to occur when the heating current is naturally reduced or paused, thereby minimizing the impact on overall heating efficiency while obtaining sufficient impedance data for accurate state of charge estimation.
2Manufacturing precision
If heating current is adjusted based on real-time measurements, then temperature control precision is improved, but system complexity increases
Solution Approach 1:
The patent employs a feedback control mechanism where impedance measurements and temperature readings are continuously monitored, and the heating current is dynamically adjusted based on these measurements. The controller modifies the heating current magnitude according to the estimated state of charge derived from impedance data, ensuring precise temperature control while preventing overheating or underheating conditions.
3Measurement precision
If impedance measurements are performed at multiple frequencies, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent performs impedance measurements at multiple frequencies to accurately characterize the battery's electrochemical state, but limits the measurement to a sufficient subset of frequencies rather than exhaustive spectral analysis. This partial action approach provides adequate precision for state of charge estimation while keeping the measurement time within acceptable limits for practical battery heating applications.
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
Provides uniform and controllable battery heating with reduced steady-state temperature errors, improves heating rate control, and adjusts for cell aging, ensuring accurate impedance and temperature measurements without significantly affecting the temperature rise rate.
Implementation Method 1
heating a battery system to a desired temperature by applying an alternating current (AC) heating current to the battery system
Implementation Method 2
performing a periodic impedance measurement, the periodic impedance measurement including application of a measurement signal having a selected frequency range to the battery system
Data Source
AI summary
A device for thermal control of a battery system includes a heating control module configured to generate an alternating current (AC) heating current and heat the battery system to a desired temperature by applying the AC heating current to the battery system over a selected heating time duration. The heating control module is configured to monitor a rate of increase of a temperature of the battery system during the applying, during the heating time duration, perform a periodic impedance measurement, the periodic impedance measurement including application of a measurement signal having a selected frequency range to the battery system for a measurement period, a length of the measurement period select to minimize a difference between a desired rate of increase and the monitored rate of increase, and adjust the AC heating current during the applying based on the temperature and the impedance measurement.