Parallel Battery Charger Voltage Switching for SOC Balance
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Solution Overview
Problem
Existing battery charging techniques for parallel-arrangement battery packs often result in unbalanced states of charge (SOC) among secondary batteries, leading to inefficient charging and potential overcharging, as they require individual circuitry and are prone to heating issues or fixed-time charging that does not account for varying battery characteristics.
Innovation Solution
A battery charger that initiates charging with a first charge parameter value, adjusts to a second value to ensure all batteries reach full charge simultaneously, and terminates charging when at least one battery is fully charged, using either charge voltage or current adjustments to maintain balanced SOC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If charging is terminated when one secondary battery reaches full charge, then charging time is reduced, but unbalanced SOCs occur among batteries
Solution Approach 1:
The patent applies dynamics by switching between two charging modes (constant current and constant voltage) based on the charging state. The system dynamically adjusts the charging parameter from constant current to constant voltage when the battery voltage reaches a predetermined threshold, enabling all batteries to reach full charge simultaneously while maintaining SOC balance.
2Stability of the object's composition
If individual charging termination is implemented, then SOC balance is improved, but device complexity increases due to required individual charging circuits
Solution Approach 1:
The patent merges all secondary batteries into a single parallel-arrangement battery pack with unified charging control. By using constant voltage charging after the switching point, all batteries share the same charging circuit and control logic, eliminating the need for individual charging circuits while maintaining SOC balance through the inherent characteristics of parallel charging with voltage switching.
3Device complexity
If fixed-time charging is applied, then device complexity is reduced, but unbalanced SOCs occur when batteries start at different SOCs
Solution Approach 1:
The patent changes the charging parameter from fixed-time control to voltage-based control. By monitoring battery voltage and switching to constant voltage charging when a predetermined voltage threshold is reached, the system ensures all batteries charge to full capacity regardless of their initial SOC states, maintaining SOC balance without complex control logic.
4Measurement precision
If heating effects are considered for accurate SOC determination, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts and addresses the heating effect by separately managing heat generation through constant voltage charging control. By switching to constant voltage mode when the voltage threshold is reached, the system reduces charging current and heat generation, allowing accurate SOC determination based on voltage alone without needing to compensate for heating effects in real-time.
Data Source
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AI summary
Charging is started with charge voltage set to a first voltage value (lower than a normal charge voltage) by a charge voltage change means, the first voltage value being predetermined to ensure that secondary batteries constituting a parallel-arrangement battery pack are charged up to and maintained at a predetermined SOC lower than full charge (between 80 and 90% of full charge). When a charge current detection means detects that charge current has decreased to a predetermined value A1, the charge voltage is set to a second voltage value (normal charge voltage) higher than the first voltage value by the charge voltage change means, the second voltage value being predetermined to enable the secondary batteries to be charged up to full charge. When a battery SOC detection means detects that at least one of the secondary batteries has reached full charge, charging is terminated.