Parallel Battery Charging Control for Accurate SOC Calibration
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Solution Overview
Problem
In power storage systems with multiple batteries connected in parallel, it is challenging to fully charge all batteries without using an additional battery for adjustment, which increases costs and reduces estimation accuracy of the state of charge (SOC).
Innovation Solution
A power storage system that includes a power converter and a control device to manage the charging of multiple batteries connected in parallel, where the control device ensures that each battery is fully charged by adjusting the power storage amount of other batteries, eliminating the need for a separate adjustment battery. The system calculates errors, self-discharge variations, and impedance variations to set predetermined times for full charging, thereby improving SOC estimation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an assembled battery for adjustment is used to fully charge each assembled battery, then the SOC estimation accuracy is improved, but the device complexity and cost increase
Solution Approach 1:
The system uses the assembled batteries themselves to perform the charging adjustment function. When one assembled battery needs full charging, the control device allocates charging power from other assembled batteries in the parallel connection, allowing the system to self-adjust without external intervention or dedicated adjustment equipment.
Solution Approach 2:
The assembled batteries serve multiple functions: they provide power storage, enable power exchange with external systems, and simultaneously function as adjustment batteries for each other. Each assembled battery can both receive and provide charging power, eliminating the need for dedicated adjustment equipment.
2Measurement precision
If an assembled battery for adjustment is used to fully charge each assembled battery, then the SOC estimation accuracy is improved, but the cost increases
Solution Approach 1:
The system uses the assembled batteries themselves to perform the charging adjustment function. When one assembled battery needs full charging, the control device allocates charging power from other assembled batteries in the parallel connection, allowing the system to self-adjust without external intervention or dedicated adjustment equipment.
Solution Approach 2:
The assembled batteries serve multiple functions: they provide power storage, enable power exchange with external systems, and simultaneously function as adjustment batteries for each other. Each assembled battery can both receive and provide charging power, eliminating the need for dedicated adjustment equipment.
3Measurement precision
If the control device charges one assembled battery to full charge, then the SOC estimation accuracy of that battery is improved, but the charging time increases
Solution Approach 1:
The control device periodically monitors the charging status of each assembled battery and dynamically adjusts charging allocation. When one battery approaches full charge, the system switches to charging other batteries, creating a periodic rotation that ensures all batteries achieve full charge status over time without excessive waiting periods.
Solution Approach 2:
The charging allocation is dynamically adjusted based on real-time SOC status of each assembled battery. The control device continuously monitors and redistributes charging power, allowing the system to adapt to changing battery states and minimize total charging time while ensuring each battery reaches full charge periodically.
Data Source
AI summary
The power storage system includes a power converter, a plurality of assembled batteries, and a control device. When there is a first assembled battery in which a predetermined time has elapsed since the previous full charge of the plurality of assembled batteries when each of the assembled batteries is charged, the control device charges the first assembled battery until the full charge, and adjusts the storage amount of the second assembled battery other than the first assembled battery in the plurality of assembled batteries so that the sum of the storage amounts after the charge of each of the assembled batteries becomes a predetermined amount.