Hybrid Battery Voltage Estimation via Circuit Model Iteration
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Solution Overview
Problem
Hybrid secondary batteries with different electrochemical characteristics connected in parallel face challenges in accurately estimating voltage due to voltage profiles with inflection points, leading to errors in state of charge measurement.
Innovation Solution
An apparatus and method using an iterative algorithm that measures operating current and employs a circuit model with open-circuit voltage and impedance elements to estimate voltage, allowing for accurate estimation even near inflection points by correlating state of charge with open-circuit voltage data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If direct voltage measurement is used near the inflection point, then measurement simplicity is maintained, but measurement precision deteriorates due to small voltage variation relative to SOC change
Solution Approach 1:
The patent introduces an intermediary estimation approach by using a circuit model with open-circuit voltage and impedance elements as mediators between the measured current and the estimated voltage. Instead of directly relying on the problematic voltage measurement near the inflection point, the system uses current measurements combined with model-based voltage estimation to achieve accurate results.
Solution Approach 2:
The patent replaces the direct electrical voltage measurement system with an iterative estimation system based on circuit models and mathematical calculations. The estimation unit substitutes the direct measurement approach by calculating voltage through iterative algorithms that use current measurements and model parameters to derive accurate voltage values even near inflection points.
2Adaptability or versatility
If hybrid secondary batteries with different electrochemical characteristics are connected in parallel, then energy capacity and application versatility are improved, but voltage estimation reliability deteriorates due to inflection points in voltage profile
Solution Approach 1:
The patent segments the voltage estimation problem by treating each battery type in the hybrid configuration with its own dedicated circuit model (first circuit unit and second circuit unit). Each unit has its own open-circuit voltage element and impedance element tailored to the specific electrochemical characteristics of that battery type, allowing accurate individual estimation that contributes to reliable overall hybrid battery voltage estimation.
Solution Approach 2:
The patent changes the estimation parameters by using iterative algorithms that dynamically adjust the estimation based on measured current and model responses. The system modifies the approach by using multiple iterations with updated parameters to converge on accurate voltage estimates, thereby maintaining reliability despite the complexity of hybrid configurations with different electrochemical characteristics.
3Measurement precision
If iterative estimation algorithm is used, then voltage estimation accuracy is improved near inflection points, but device complexity increases
Solution Approach 1:
The patent creates a universal estimation framework where a single control unit handles multiple functions: it manages different circuit models for various battery types, performs iterative calculations, and adapts to different operating conditions. This multi-functional approach consolidates complexity into one versatile unit rather than requiring separate dedicated systems for each battery type or condition.
Solution Approach 2:
The iterative estimation algorithm is self-correcting and self-adjusting. The control unit automatically performs multiple iterations, using the measured current and model responses to refine voltage estimates without external intervention. The system serves itself by automatically converging on accurate solutions through the iterative process, reducing the need for complex external control mechanisms.
Data Source
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AI summary
An apparatus and a method for estimating voltage of a hybrid secondary battery are provided, in which the hybrid secondary battery includes a first secondary battery and a second secondary battery having different electrochemical characteristics from each other and being connected in parallel with each other. The apparatus includes a sensor unit which measures an operating current of the hybrid secondary battery, and a control unit which estimates the voltage of the hybrid secondary battery using the operating current, and a voltage equation derived from a circuit model including a first circuit unit which simulates a voltage variation of the first secondary battery by a first open-circuit voltage element and optionally, a first impedance element, and a second circuit unit which is connected in parallel with the first circuit unit and simulates a voltage variation of the second secondary battery by a second open-circuit voltage element and optionally, a second impedance element.