Dynamic Battery Charge Compensation for Voltage Drop
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Solution Overview
Problem
Existing battery charging technologies face inefficiencies due to voltage drops within battery packs, leading to longer charge times and potential cell damage, as they lack dynamic compensation for internal resistance and current variations.
Innovation Solution
A method and apparatus that measure and compensate for voltage drops across the battery pack's internal resistance, protection devices, and sense resistor by computing a compensation voltage, which is added to the nominal charging voltage to optimize the charging current and voltage applied to the cells, ensuring safe and efficient charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a fixed compensation voltage is added during the CV phase, then charging time is reduced and efficiency is improved, but cell damage risk increases due to potential overcharging
Solution Approach 1:
The patent implements dynamic compensation voltage adjustment based on real-time charging current measurements. The compensation voltage varies throughout the charging process rather than remaining fixed, allowing the system to optimize charging speed while preventing overcharging by adapting to changing battery conditions
Solution Approach 2:
The system continuously monitors charging current and uses this feedback to adjust the compensation voltage dynamically. This closed-loop control ensures that the compensation voltage is optimized for charging efficiency while preventing cell damage by responding to actual charging conditions
2Loss of energy
If a fixed compensation voltage is used, then some voltage drop compensation is achieved, but it cannot account for changes in battery pack IR drop as charging current changes
Solution Approach 1:
The compensation voltage is made dynamic by continuously adjusting it based on measured charging current. This allows the system to adapt to changing IR drops as current varies during charging, rather than using a static compensation value
Solution Approach 2:
The system changes the compensation voltage parameter in response to changing charging current. By adjusting this parameter dynamically, the system maintains effective voltage drop compensation across different charging conditions
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 significantly reduces charge time and enhances charging efficiency by maintaining optimal charging voltage levels, preventing cell damage and overcharging, while dynamically adjusting to changes in internal resistance and current.
Implementation Method 1
compensating for voltage drops within the battery pack, so as to reduce charge time and increase charging efficiency
Implementation Method 2
A battery pack is a series-connected set of one or more cells... a constant current is first injected into a battery until its terminal voltage rises
Data Source
AI summary
A battery charger and method for a rechargeable battery pack which includes various elements in series with the cells to be charged, including but not limited to current control FETs, a fuse, current sense resistor, and internal series impedance of the series connected cells to be charged. The charging current Ichg flowing through these series elements reduces the voltage applied to the cells, thus lengthening charging time. A compensation voltage Vcomp, which when added to the nominal charging voltage for the series connected cells overcomes these voltage drops, facilitates more efficient charging while avoiding over-voltage damage to the cells. Three voltages representing substantially all of the voltage drops reducing the charging voltage on the cells, are summed, and the result is a compensation voltage which is utilized to change the nominal charge voltage for the battery to overcome these voltage drops.