Power Supply Control Device for Battery Capacity Estimation
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Solution Overview
Problem
Existing power supply control devices for vehicles do not accurately estimate the full charge capacity of batteries, particularly lithium iron phosphate batteries, due to limited timing and scheme for the estimation process, which can lead to inaccuracies and inefficiencies in securing a sufficient state of charge difference (ΔSOC) for precise capacity calculation.
Innovation Solution
A power supply control device that includes a determination unit to assess the need for correcting the full charge capacity based on predetermined values and conditions, such as elapsed time, deteriorating state, and temperature exposure, and a power transfer unit to transfer power from one battery to another when necessary, allowing for accurate estimation using a current integration method at optimal times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the full charge capacity estimating process is performed frequently to capture the latest battery capacity, then the accuracy of SOC calculation is improved, but the power consumption and processing load increase
Solution Approach 1:
The system changes the timing parameter of the estimation process based on battery SOC thresholds. Estimation is performed when SOC reaches predetermined thresholds (e.g., 80% or higher), transforming the continuous estimation requirement into discrete threshold-based triggering, thereby reducing overall processing frequency while maintaining accuracy when needed.
Solution Approach 2:
The system uses the battery's own charging/discharging cycles to naturally create the conditions needed for estimation. When the battery reaches certain SOC levels during normal operation, the system automatically performs estimation without requiring external intervention or additional power input, utilizing the battery's self-charging characteristic.
2Measurement precision
If external charging is performed to estimate full charge capacity, then the estimation can be conducted, but it is not always possible to secure sufficient SOC difference (ΔSOC) for accurate estimation
Solution Approach 1:
The system dynamically adjusts the estimation strategy based on real-time battery conditions. Instead of relying solely on external charging, the system can perform estimation during internal power transfer between batteries when SOC conditions are favorable, adapting the estimation timing to actual operational conditions rather than following a fixed external charging schedule.
Solution Approach 2:
The system proactively monitors battery SOC levels and prepares for estimation when conditions are favorable. By anticipating when sufficient SOC difference will be available (either through external charging or internal transfer), the system can plan and execute estimation at optimal moments, rather than reacting passively to charging opportunities.
3Measurement precision
If power is transferred from one battery to another to enable estimation, then sufficient SOC difference can be secured, but additional control complexity is introduced
Solution Approach 1:
The power transfer mechanism serves multiple functions: it not only enables capacity estimation by creating SOC difference but also balances battery charges, extends battery life, and provides backup power capabilities. This multi-functionality justifies the added control complexity by delivering multiple benefits from a single system addition.
Solution Approach 2:
The system combines the estimation process with the existing battery management and power transfer infrastructure. Rather than adding a separate estimation system, the estimation function is integrated into the power transfer control logic, utilizing the same sensors, processors, and control mechanisms already present in the dual-battery system.
4Ease of operation
If the estimation process is performed at limited opportunities such as external charging, then the system is simple to operate, but the full charge capacity may not be updated timely due to battery deterioration
Solution Approach 1:
The system continuously monitors battery parameters (SOC, temperature, current) and uses this feedback to determine when estimation should be performed. The control unit receives real-time data from sensors and automatically triggers estimation when predetermined conditions are met, creating a closed-loop system that balances simplicity with timely updates based on actual battery state.
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
The solution enables precise estimation of the full charge capacity with high accuracy by securing a large ΔSOC and considering battery deterioration and temperature factors, reducing measurement errors and power consumption, while avoiding inefficient power transfers.
Implementation Method 1
a power transfer unit configured to transfer a predetermined power from the battery to another battery
Data Source
AI summary
A power supply control device that estimates a full charge capacity of a battery includes a determination unit that determines whether there is a need to correct a currently estimated full charge capacity when a state of charge of the battery is equal to or greater than a first predetermined value at a timing at which a power supply of the vehicle is turned OFF, a power transfer unit that transfers a predetermined power from the battery to another battery when the determination unit determines that there is a need to correct the currently estimated full charge capacity, and a capacity estimation unit that performs a predetermined full charge capacity estimating process on the battery at a timing at which the power supply of the vehicle is turned ON after power transfer by the power transfer unit or during the power transfer by the power transfer unit.