Battery Pack Energy Calculation Using Temperature-Dependent Internal Resistance
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Solution Overview
Problem
Existing methods for calculating the residual capacity of a battery pack do not accurately consider internal resistances, leading to inaccuracies in determining the remaining electric energy.
Innovation Solution
A battery pack with a voltage and current measurement unit, a temperature measurement unit, and a calculation unit that calculates a first electric energy balance based on voltages and currents, determines internal resistances based on temperatures, and calculates a second electric energy balance to accurately determine the accumulated electric energy balance by considering internal resistances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If internal resistances are not considered in the calculation method, then the calculation process is simple, but the accuracy of remaining electric energy determination deteriorates
Solution Approach 1:
The patent applies parameter changes by introducing temperature as a variable parameter that affects internal resistance. The calculation unit determines internal resistance values based on measured battery temperatures, and these temperature-dependent resistance values are then incorporated into the electric energy balance calculation. This transforms the calculation from a simple voltage-integration method to a more comprehensive model that accounts for temperature-induced resistance variations, thereby improving accuracy while maintaining manageable computational complexity.
2Measurement precision
If internal resistances are considered in the calculation method, then the accuracy of remaining electric energy determination is improved, but the calculation process complexity increases
Solution Approach 1:
The patent segments the electric energy calculation into distinct components: the first electric energy balance calculated from voltage and current measurements, and the second electric energy balance calculated from internal resistance losses. By dividing the total energy calculation into these separable parts, the system can accurately account for resistance effects without creating an intractably complex unified calculation, thus improving precision while controlling computational complexity.
Solution Approach 2:
The calculation unit performs preliminary determination of internal resistance values based on temperature measurements before incorporating them into the main energy balance calculation. This preliminary action allows the system to prepare resistance correction factors in advance, streamlining the overall calculation process and reducing the computational burden during real-time energy assessment.
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
This approach allows for accurate calculation of the remaining electric energy in the battery pack by accounting for the loss component due to internal resistances, providing a more precise estimation of the battery's residual capacity.
Implementation Method 1
a voltage and current measurement unit that measures voltages and currents of the battery units
Implementation Method 2
a temperature measurement unit that measures temperatures of the battery units
Implementation Method 3
determines internal resistances of the battery units on the basis of the temperatures, and calculates a second electric energy balance of the internal resistances on the basis of the currents and the internal resistances
Data Source
AI summary
A battery pack (10) includes a plurality of battery cells (100) which are connected in series to each other, a voltage and current measurement unit (voltage and current measurement unit (200)), a temperature measurement unit (temperature measurement unit (300)), and a calculation unit (calculation unit (420)) provided in an arithmetic operation communication unit (400). The calculation unit (420) calculates a “first electric energy balance” of the battery cells (100) on the basis of voltages and currents, determines internal resistances of the battery cells (100) on the basis of the temperatures, and calculates a “second electric energy balance” of the internal resistances on the basis of currents and the internal resistances. Thereby, the calculation unit (420) calculates an “accumulated electric energy balance” (electric energy E(t)) accumulated in the battery cells (100) on the basis of the first electric energy balance of the battery cells (100) and the second electric energy balance of the internal resistances.