Battery SOH Estimation via Impulse Response Convolution
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Solution Overview
Problem
Conventional methods for estimating the State-Of-Health (SOH) of chemical batteries, such as Li-Ion, Ni-MH, Ni-Cd, and Lead-acid, are expensive, time-consuming, damage the batteries, and lack real-time online monitoring capabilities, making them inefficient for accurate and timely health assessment.
Innovation Solution
A novel method using battery impulse response, which involves measuring terminal current and voltage, estimating state-of-charge, determining impulse responses from look-up tables, and comparing measured voltages with calculated values to determine SOH, allowing for online and real-time SOH estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If full or partial discharge test is used to estimate SOH, then measurement precision is improved, but loss of time increases and object-affected harmful factors worsen due to battery damage
Solution Approach 1:
The patent applies periodic action by using a series of current pulses instead of continuous discharge. Multiple pulses are applied in sequence, with each pulse followed by a rest period, allowing the battery to partially recover. This periodic stimulation enables SOH estimation through impedance changes without requiring prolonged continuous discharge testing.
Solution Approach 2:
The patent implements skipping by using brief current pulses rather than prolonged discharge. The impulse current is applied for very short durations (milliseconds to seconds), rushing through the measurement process quickly to capture impedance characteristics without subjecting the battery to extended stress that would cause damage or require lengthy test periods.
2Measurement precision
If full or partial discharge test is used to estimate SOH, then measurement precision is improved, but object-affected harmful factors worsen due to battery damage from deep discharge
Solution Approach 1:
The patent applies partial action by using current pulses of controlled magnitude and duration that provide sufficient stimulation to measure impedance changes but remain below the threshold that causes significant battery damage. The impulse current is strong enough to elicit a measurable response but brief and controlled enough to avoid harmful deep discharge effects.
Solution Approach 2:
The patent implements cushioning by incorporating rest periods between current pulses and by using impulse currents that inherently limit energy delivery. The brief pulse duration and controlled magnitude act as a cushion, preventing excessive stress accumulation that would lead to battery damage while still providing adequate measurement signal.
3Ease of operation
If ohmic measurement techniques are used to estimate SOH, then ease of operation is improved, but measurement precision worsens due to sensitivity to measurement error and contact quality
Solution Approach 1:
The patent introduces impedance measurement as an intermediary approach between simple ohmic measurement and complex discharge testing. By measuring the battery's impedance response to current pulses, the system obtains a more reliable indicator of SOH that is less sensitive to contact resistance and measurement errors than direct ohmic measurements, while still being easier to implement than full discharge tests.
Solution Approach 2:
The patent replaces the mechanical/electrical contact-based ohmic measurement system with an electrochemical impedance measurement system. Instead of relying on direct voltage-current relationships that are sensitive to contact quality, the method uses the battery's dynamic response to pulsed current, substituting a more robust measurement paradigm that captures the battery's intrinsic electrochemical state.
4Measurement precision
If conventional SOH estimation methods are used, then measurement precision may be improved, but productivity worsens due to offline testing requirements and time-consuming procedures
Solution Approach 1:
The patent implements continuity by enabling online SOH estimation that can be performed while the battery is in service. The impulse current method allows for continuous or frequent monitoring without requiring the battery to be taken offline for extended discharge tests, maintaining productive operation while continuously assessing battery health.
Solution Approach 2:
The patent applies dynamics by using time-varying current pulses instead of static DC measurements. The impulse current creates a dynamic measurement scenario where the battery's transient response captures impedance characteristics that reflect SOH, enabling rapid assessment that adapts to the battery's actual operating state rather than requiring static offline testing conditions.
Data Source
AI summary
Estimation of a state-of-health (SOH) in a battery are disclosed. An example technique includes determining if a terminal voltage of the chemical battery differs from a calculated terminal voltage. In response to determining that the terminal voltage of the chemical battery differs from the calculated terminal voltage, calculating a range of voltages by taking the convolution of a terminal current of the chemical battery with a range of impulse responses from a look up table of impulse responses corresponding to different SOH. The technique further includes comparing the terminal voltage of the chemical battery with the range of calculated voltages to determine a second impulse response that corresponds to the case where the terminal voltage matches the calculated voltage. The look up table of impulse responses corresponding to different SOHs is then used to determine the SOH of the chemical battery from the second impulse response.