Vehicle Battery Charging Control for Rapid Polarization Relief
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Solution Overview
Problem
Continuous external charging of electrified vehicles leads to polarization of the power storage device for traveling, which decreases the accuracy of estimating the full charge level, necessitating a method to quickly reduce polarization after charging.
Innovation Solution
A vehicle configuration including a control device that lowers the charging state of the auxiliary power storage device and drives the converter after external charging to increase discharge power, thereby quickly reducing polarization in the primary power storage device, which may include an all-solid-state battery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If external charging is performed continuously, then the power storage device is charged, but polarization occurs and estimation accuracy decreases
Solution Approach 1:
The control device performs preliminary action by driving the converter to discharge power from the first power storage device to the second power storage device before performing full charge level estimation. This preliminary discharge action reduces polarization that occurred during charging, thereby improving the accuracy of subsequent estimation measurements.
2Loss of time
If the converter is driven to reduce polarization, then polarization is eliminated quickly, but discharge power is increased
Solution Approach 1:
The second power storage device acts as an intermediary to absorb the discharge power from the first power storage device. This allows the converter to be driven at high power to quickly reduce polarization in the first power storage device, while the second power storage device absorbs the energy that would otherwise be lost, converting it into useful stored energy.
3Productivity
If the charging state of the second power storage device is lowered, then the converter can be driven more effectively, but the auxiliary device power is reduced
Solution Approach 1:
The system dynamically adjusts the charging state of the second power storage device based on operational needs. The charging state is lowered specifically during the period when polarization reduction is required, and can be restored afterward. This dynamic adjustment allows the converter to be driven effectively for polarization reduction while maintaining adequate auxiliary device power when needed.
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 configuration allows for rapid elimination of polarization in the power storage device, enabling earlier and more accurate estimation of the full charge level, particularly effective for all-solid-state batteries prone to polarization and reaction unevenness.
Implementation Method 1
The converter is configured to step down discharge power of the first power storage device and supply the stepped-down power to the second power storage device
Implementation Method 2
Continuous charging such as external charging may cause polarization of the first power storage device
Data Source
AI summary
Vehicles include a main battery, an auxiliary battery, charging relays, a DC/DC converter, and an ECU. The charging relay is used to perform external charging for charging the main battery by the power equipment. The DC/DC converter is configured to step down the discharging power of the main battery and to provide the stepped-down power to the auxiliary battery. ECU controls the DC/DC converter. ECU lowers the charging state of the auxiliary battery from the first state to the second state by the end of the external charging, and drives the DC/DC converter after the end of the external charging.